Estimation of the specific surface area for a porous carrier.

PubMed

Levstek, Meta; Plazl, Igor; Rouse, Joseph D

2010-03-01

In biofilm systems, treatment performance is primarily dependent upon the available biofilm growth surface area in the reactor. Specific surface area is thus a parameter that allows for making comparisons between different carrier technologies used for wastewater treatment. In this study, we estimated the effective surface area for a spherical, porous polyvinyl alcohol (PVA) gel carrier (Kuraray) that has previously demonstrated effectiveness for retention of autotrophic and heterotrophic biomass. This was accomplished by applying the GPS-X modeling tool (Hydromantis) to a comparative analysis of two moving-bed biofilm reactor (MBBR) systems. One system consisted of a lab-scale reactor that was fed synthetic wastewater under autotrophic conditions where only the nitrification process was studied. The other was a pre-denitrification pilot-scale plant that was fed real, primary-settled wastewater. Calibration of an MBBR process model for both systems indicated an effective specific surface area for PVA gel of 2500 m2/m3, versus a specific surface area of 1000 m2/m3 when only the outer surface of the gel beads is considered. In addition, the maximum specific growth rates for autotrophs and heterotrophs were estimated to be 1.2/day and 6.0/day, respectively.

Musculoaponeurotic Area of the Hip and Clinicophotographic Scaling System

PubMed Central

Mena-Chávez, J. Alejandro

2015-01-01

Background: With the evolution of body contouring, few innovative alternatives have been developed for cosmetic treatment in the hip area. Methods: A multicenter controlled study was conducted, including a prior review of the literature regarding the hip area. Dissections were performed on 4 male cadavers, outlining the “musculoaponeurotic area of the hip.” The area was subdivided into anterior and posterior surfaces. A clinical study was conducted in 79 patients, obtaining a scale by using the most prominent points on the sides of both thighs as the main reference. With the lines marked on photographs and the measurements, a “clinicophotographic scaling system” was designed. Results: The anterior surface corresponds to the tensor fasciae latae and its tendon as well as to the aponeurosis of the gluteus medius. The posterior surface corresponds with the iliotibial tract and the tendon insertions of the gluteus maximus. The average dimensions of the cadaver “musculoaponeurotic area of the hip” are as follows: length, 17.5 cm, and width, 11.5 cm. Using the “clinicophotographic scaling system,” the dimensions are as follows: length, 14.9 cm, and width, 10.3 cm. Conclusions: The “musculoaponeurotic area of the hip” was defined involving muscles, tendons, aponeurosis, fascia, subcutaneous cellular tissue, and skin. The borders were established using important anatomical points that determine the length and width of the area. The “clinicophotographic scaling system” was used to clinically calculate the length and width of the area. By examination and palpation, the borders and dimensions of this area could be determined. PMID:26180724

Leaf area dynamics of conifer forests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Margolis, H.; Oren, R.; Whitehead, D.

1995-07-01

Estimating the surface area of foliage supported by a coniferous forest canopy is critical for modeling its biological properties. Leaf area represents the surface area available for the interception of energy, the absorption of carbon dioxide, and the diffusion of water from the leaf to the atmosphere. The concept of leaf area is pertinent to the physiological and ecological dynamics of conifers at a wide range of spatial scales, from individual leaves to entire biomes. In fact, the leaf area of vegetation at a global level can be thought of as a carbon-absorbing, water-emitting membrane of variable thickness, which canmore » have an important influence on the dynamics and chemistry of the Earth`s atmosphere over both the short and the long term. Unless otherwise specified, references to leaf area herein refer to projected leaf area, i.e., the vertical projection of needles placed on a flat plane. Total leaf surface area is generally from 2.0 to 3.14 times that of projected leaf area for conifers. It has recently been suggested that hemisurface leaf area, i.e., one-half of the total surface area of a leaf, a more useful basis for expressing leaf area than is projected area. This chapter is concerned with the dynamics of coniferous forest leaf area at different spatial and temporal scales. In the first part, we consider various hypotheses related to the control of leaf area development, ranging from simple allometric relations with tree size to more complex mechanistic models that consider the movement of water and nutrients to tree canopies. In the second part, we consider various aspects of leaf area dynamics at varying spatial and temporal scales, including responses to perturbation, seasonal dynamics, genetic variation in crown architecture, the responses to silvicultural treatments, the causes and consequences of senescence, and the direct measurement of coniferous leaf area at large spatial scales using remote sensing.« less

Evolution of the Contact Area with Normal Load for Rough Surfaces: from Atomic to Macroscopic Scales.

PubMed

Huang, Shiping

2017-11-13

The evolution of the contact area with normal load for rough surfaces has great fundamental and practical importance, ranging from earthquake dynamics to machine wear. This work bridges the gap between the atomic scale and the macroscopic scale for normal contact behavior. The real contact area, which is formed by a large ensemble of discrete contacts (clusters), is proven to be much smaller than the apparent surface area. The distribution of the discrete contact clusters and the interaction between them are key to revealing the mechanism of the contacting solids. To this end, Green's function molecular dynamics (GFMD) is used to study both how the contact cluster evolves from the atomic scale to the macroscopic scale and the interaction between clusters. It is found that the interaction between clusters has a strong effect on their formation. The formation and distribution of the contact clusters is far more complicated than that predicted by the asperity model. Ignorance of the interaction between them leads to overestimating the contacting force. In real contact, contacting clusters are smaller and more discrete due to the interaction between the asperities. Understanding the exact nature of the contact area with the normal load is essential to the following research on friction.

Evolution of the Contact Area with Normal Load for Rough Surfaces: from Atomic to Macroscopic Scales

NASA Astrophysics Data System (ADS)

Huang, Shiping

2017-11-01

The evolution of the contact area with normal load for rough surfaces has great fundamental and practical importance, ranging from earthquake dynamics to machine wear. This work bridges the gap between the atomic scale and the macroscopic scale for normal contact behavior. The real contact area, which is formed by a large ensemble of discrete contacts (clusters), is proven to be much smaller than the apparent surface area. The distribution of the discrete contact clusters and the interaction between them are key to revealing the mechanism of the contacting solids. To this end, Green's function molecular dynamics (GFMD) is used to study both how the contact cluster evolves from the atomic scale to the macroscopic scale and the interaction between clusters. It is found that the interaction between clusters has a strong effect on their formation. The formation and distribution of the contact clusters is far more complicated than that predicted by the asperity model. Ignorance of the interaction between them leads to overestimating the contacting force. In real contact, contacting clusters are smaller and more discrete due to the interaction between the asperities. Understanding the exact nature of the contact area with the normal load is essential to the following research on friction.

Surface area-volume ratios in insects.

PubMed

Kühsel, Sara; Brückner, Adrian; Schmelzle, Sebastian; Heethoff, Michael; Blüthgen, Nico

2017-10-01

Body mass, volume and surface area are important for many aspects of the physiology and performance of species. Whereas body mass scaling received a lot of attention in the literature, surface areas of animals have not been measured explicitly in this context. We quantified surface area-volume (SA/V) ratios for the first time using 3D surface models based on a structured light scanning method for 126 species of pollinating insects from 4 orders (Diptera, Hymenoptera, Lepidoptera, and Coleoptera). Water loss of 67 species was measured gravimetrically at very dry conditions for 2 h at 15 and 30 °C to demonstrate the applicability of the new 3D surface measurements and relevance for predicting the performance of insects. Quantified SA/V ratios significantly explained the variation in water loss across species, both directly or after accounting for isometric scaling (residuals of the SA/V ∼ mass 2/3 relationship). Small insects with a proportionally larger surface area had the highest water loss rates. Surface scans of insects to quantify allometric SA/V ratios thus provide a promising method to predict physiological responses, improving the potential of body mass isometry alone that assume geometric similarity. © 2016 Institute of Zoology, Chinese Academy of Sciences.

Occurrence and behavior of the herbicide Prometon in the hydrologic system

USGS Publications Warehouse

Capel, P.D.; Spexet, A.H.; Larson, S.J.

1999-01-01

Prometon, a triazine herbicide, is used for total vegetation control on industrial sites, on noncrop areas on farms, in and under asphalt, and to a small extent by homeowners. Prometon has often been detected in surface water and groundwater in studies reported in the literature, but its presence is seldom discussed, partly because of its infrequent inclusion on lists of herbicides used in either agricultural or urban areas. In recent large-scale studies by the U.S. Geological Survey, prometon has been the most commonly detected herbicide in surface water and groundwater in urban areas and the third and fourth most commonly detected herbicide in groundwater and surface water, respectively, in agricultural areas. It also has been detected in rain. The frequent detection of prometon in the environment is discussed in relation to its use practices and predicted environmental behavior. Prometon is compared to atrazine, a structurally similar agricultural triazine herbicide that is one of the most studied and most commonly detected herbicides found in the hydrologic environment. The environmental data presented here demonstrate the wide-scale occurrence of prometon in all components of the hydrologic system, particularly in the surface water and groundwater of urban areas.Prometon, a triazine herbicide, is used for total vegetation control on industrial sites, on noncrop areas on farms, in and under asphalt, and to a small extent by homeowners. Prometon has often been detected in surface water and groundwater in studies reported in the literature, but its presence is seldom discussed, partly because of its infrequent inclusion on lists of herbicides used in either agricultural or urban areas. In recent large-scale studies by the U.S. Geological Survey, prometon has been the most commonly detected herbicide in surface water and groundwater in urban areas and the third and fourth most commonly detected herbicide in groundwater and surface water, respectively, in agricultural areas. It also has been detected in rain. The frequent detection of prometon in the environment is discussed in relation to its use practices and predicted environmental behavior. Prometon is compared to atrazine, a structurally similar agricultural triazine herbicide that is one of the most studied and most commonly detected herbicides found in the hydrologic environment. The environmental data presented here demonstrate the wide-scale occurrence of prometon in all components of the hydrologic system, particularly in the surface water and groundwater of urban areas.

The scaling of urban surface water abundance and impairment with city size

NASA Astrophysics Data System (ADS)

Steele, M. K.

2018-03-01

Urbanization alters surface water compared to nonurban landscapes, yet little is known regarding how basic aquatic ecosystem characteristics, such as the abundance and impairment of surface water, differ with population size or regional context. This study examined the abundance, scaling, and impairment of surface water by quantifying the stream length, water body area, and impaired stream length for 3520 cities in the United States with populations from 2500 to 18 million. Stream length, water body area, and impaired stream length were quantified using the National Hydrography Dataset and the EPA's 303(d) list. These metrics were scaled with population and city area using single and piecewise power-law models and related to biophysical factors (precipitation, topography) and land cover. Results show that abundance of stream length and water body area in cities actually increases with city area; however, the per person abundance decreases with population size. Relative to population, impaired stream length did not increase until city populations were > 25,000 people, then scaled linearly with population. Some variation in abundance and impairment was explained by biophysical context and land cover. Development intensity correlated with stream density and impairment; however, those relationships depended on the orientation of the land covers. When high intensity development occupied the local elevation highs (+ 15 m) and undeveloped land the elevation lows, the percentage of impaired streams was less than the opposite land cover orientation (- 15 m) or very flat land. These results show that surface water abundance and impairment across contiguous US cities are influenced by city size and by biophysical setting interacting with land cover intensity.

Progressive Mid-latitude Afforestation: Local and Remote Climate Impacts in the Framework of Two Coupled Earth System Models

NASA Astrophysics Data System (ADS)

Lague, Marysa

Vegetation influences the atmosphere in complex and non-linear ways, such that large-scale changes in vegetation cover can drive changes in climate on both local and global scales. Large-scale land surface changes have been shown to introduce excess energy to one hemisphere, causing a shift in atmospheric circulation on a global scale. However, past work has not quantified how the climate response scales with the area of vegetation. Here, we systematically evaluate the response of climate to linearly increasing the area of forest cover over the northern mid-latitudes. We show that the magnitude of afforestation of the northern mid-latitudes determines the climate response in a non-linear fashion, and identify a threshold in vegetation-induced cloud feedbacks - a concept not previously addressed by large-scale vegetation manipulation experiments. Small increases in tree cover drive compensating cloud feedbacks, while latent heat fluxes reach a threshold after sufficiently large increases in tree cover, causing the troposphere to warm and dry, subsequently reducing cloud cover. Increased absorption of solar radiation at the surface is driven by both surface albedo changes and cloud feedbacks. We identify how vegetation-induced changes in cloud cover further feedback on changes in the global energy balance. We also show how atmospheric cross-equatorial energy transport changes as the area of afforestation is incrementally increased (a relationship which has not previously been demonstrated). This work demonstrates that while some climate effects (such as energy transport) of large scale mid-latitude afforestation scale roughly linearly across a wide range of afforestation areas, others (such as the local partitioning of the surface energy budget) are non-linear, and sensitive to the particular magnitude of mid-latitude forcing. Our results highlight the importance of considering both local and remote climate responses to large-scale vegetation change, and explore the scaling relationship between changes in vegetation cover and the resulting climate impacts.

Estimating and validating surface energy fluxes at field scale over a heterogeneous land surfaces based on two-source energy balance model (TSEB)

USDA-ARS?s Scientific Manuscript database

Accurate estimation of surface energy fluxes at field scale over large areas has the potential to improve agricultural water management in arid and semiarid watersheds. Remote sensing may be the only viable approach for mapping fluxes over heterogeneous landscapes. The Two-Source Energy Balance mode...

Pre-coalescence scaling of graphene island sizes

NASA Astrophysics Data System (ADS)

Das, Shantanu; Drucker, Jeff

2018-05-01

Graphene grown using cold-wall chemical vapor deposition on Cu surfaces follows a classical nucleation and growth mechanism. Following nucleation at the earliest growth stages, isolated crystallites grow, impinge, and coalesce to form a continuous layer. During the pre-coalescence growth regime, the size distributions of graphene crystallites exhibit scaling of the form N(s) = θ/⟨s⟩2 g(s/⟨s⟩), where s is the island area, θ is the graphene coverage, ⟨s⟩ is the average island area, N is the areal density, and g(x) is a scaling function. For graphene grown on Cu surfaces that have been annealed in a reducing Ar + H2 ambient, excellent data collapse onto a universal Avrami scaling function is observed irrespective of graphene coverage, surface roughness, or Cu grain size. This result is interpreted to indicate attachment-limited growth and desorption of diffusing C-containing species. Graphene grown on Cu surfaces that were annealed in a non-reducing environment exhibits a qualitatively different scaling function, indicating diffusion-limited growth with a lower attachment barrier combined with C detachment from the graphene edges.

Surface and mass fractals in vapor-phase aggregates

NASA Astrophysics Data System (ADS)

Hurd, Alan J.; Schaefer, Dale W.; Martin, James E.

1987-03-01

Several types of fumed-silica aggregates with differing surface areas were studied over a wide range of spatial resolution by employing both light and neutron scattering. At intermediate length scales, between 100 and 1000 Å, the aggregates are mass fractals with Dm~=1.7-2.0, in basic agreement with simulations of aggregating clusters. At short length scales below 100 Å where the nature of the surfaces of the primary particles dominates the scattering, some of the samples appear to be fractally rough. In particular, a higher surface area seems to be correlated not with smaller primary particles in the aggregates, as previously assumed, but with fractally rough surfaces having Ds as high as 2.5. These may be the first materials discovered to have both mass and surface fractal structure.

Static allometry of unicellular green algae: scaling of cellular surface area and volume in the genus Micrasterias (Desmidiales).

PubMed

Neustupa, J

2016-02-01

The surface area-to-volume ratio of cells is one of the key factors affecting fundamental biological processes and, thus, fitness of unicellular organisms. One of the general models for allometric increase in surface-to-volume scaling involves fractal-like elaboration of cellular surfaces. However, specific data illustrating this pattern in natural populations of the unicellular organisms have not previously been available. This study shows that unicellular green algae of the genus Micrasterias (Desmidiales) have positive allometric surface-to-volume scaling caused by changes in morphology of individual species, especially in the degree of cell lobulation. This allometric pattern was also detected within most of the cultured and natural populations analysed. Values of the allometric S:V scaling within individual populations were closely correlated to the phylogenetic structure of the clade. In addition, they were related to species-specific cellular morphology. Individual populations differed in their allometric patterns, and their position in the allometric space was strongly correlated with the degree of allometric S:V scaling. This result illustrates that allometric shape patterns are an important correlate of the capacity of individual populations to compensate for increases in their cell volumes by increasing the surface area. However, variation in allometric patterns was not associated with phylogenetic structure. This indicates that the position of the populations in the allometric space was not evolutionarily conserved and might be influenced by environmental factors. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Space filling minimal surfaces and sphere packings

NASA Astrophysics Data System (ADS)

Elser, Veit

1994-05-01

A space filling minimal surface is defined to be any embedded minimal surface without boundary with the property that the area and genus enclosed by any large spherical region scales in proportion to the volume of the region. The triply periodic minimal surfaces are one realization, but not necessarily the only one. By using the genus per unit volume of the surface, a meaningful comparison of surface areas can be made even in cases where there is no unit cell. Of the known periodic minimal surfaces this measure of the surface area is smallest for Schoen's FRD surface. This surface is one of several that is closely related to packings of spheres. Its low area is largely due to the fact that the corresponding sphere packing (fcc) has the maximal kissing number.

Multi-level, multi-scale resource selection functions and resistance surfaces for conservation planning: Pumas as a case study

PubMed Central

Vickers, T. Winston; Ernest, Holly B.; Boyce, Walter M.

2017-01-01

The importance of examining multiple hierarchical levels when modeling resource use for wildlife has been acknowledged for decades. Multi-level resource selection functions have recently been promoted as a method to synthesize resource use across nested organizational levels into a single predictive surface. Analyzing multiple scales of selection within each hierarchical level further strengthens multi-level resource selection functions. We extend this multi-level, multi-scale framework to modeling resistance for wildlife by combining multi-scale resistance surfaces from two data types, genetic and movement. Resistance estimation has typically been conducted with one of these data types, or compared between the two. However, we contend it is not an either/or issue and that resistance may be better-modeled using a combination of resistance surfaces that represent processes at different hierarchical levels. Resistance surfaces estimated from genetic data characterize temporally broad-scale dispersal and successful breeding over generations, whereas resistance surfaces estimated from movement data represent fine-scale travel and contextualized movement decisions. We used telemetry and genetic data from a long-term study on pumas (Puma concolor) in a highly developed landscape in southern California to develop a multi-level, multi-scale resource selection function and a multi-level, multi-scale resistance surface. We used these multi-level, multi-scale surfaces to identify resource use patches and resistant kernel corridors. Across levels, we found puma avoided urban, agricultural areas, and roads and preferred riparian areas and more rugged terrain. For other landscape features, selection differed among levels, as did the scales of selection for each feature. With these results, we developed a conservation plan for one of the most isolated puma populations in the U.S. Our approach captured a wide spectrum of ecological relationships for a population, resulted in effective conservation planning, and can be readily applied to other wildlife species. PMID:28609466

Multi-level, multi-scale resource selection functions and resistance surfaces for conservation planning: Pumas as a case study.

PubMed

Zeller, Katherine A; Vickers, T Winston; Ernest, Holly B; Boyce, Walter M

2017-01-01

The importance of examining multiple hierarchical levels when modeling resource use for wildlife has been acknowledged for decades. Multi-level resource selection functions have recently been promoted as a method to synthesize resource use across nested organizational levels into a single predictive surface. Analyzing multiple scales of selection within each hierarchical level further strengthens multi-level resource selection functions. We extend this multi-level, multi-scale framework to modeling resistance for wildlife by combining multi-scale resistance surfaces from two data types, genetic and movement. Resistance estimation has typically been conducted with one of these data types, or compared between the two. However, we contend it is not an either/or issue and that resistance may be better-modeled using a combination of resistance surfaces that represent processes at different hierarchical levels. Resistance surfaces estimated from genetic data characterize temporally broad-scale dispersal and successful breeding over generations, whereas resistance surfaces estimated from movement data represent fine-scale travel and contextualized movement decisions. We used telemetry and genetic data from a long-term study on pumas (Puma concolor) in a highly developed landscape in southern California to develop a multi-level, multi-scale resource selection function and a multi-level, multi-scale resistance surface. We used these multi-level, multi-scale surfaces to identify resource use patches and resistant kernel corridors. Across levels, we found puma avoided urban, agricultural areas, and roads and preferred riparian areas and more rugged terrain. For other landscape features, selection differed among levels, as did the scales of selection for each feature. With these results, we developed a conservation plan for one of the most isolated puma populations in the U.S. Our approach captured a wide spectrum of ecological relationships for a population, resulted in effective conservation planning, and can be readily applied to other wildlife species.

Remote sensing of exposure to NO2: Satellite versus ground-based measurement in a large urban area

NASA Astrophysics Data System (ADS)

Bechle, Matthew J.; Millet, Dylan B.; Marshall, Julian D.

2013-04-01

Remote sensing may be a useful tool for exploring spatial variability of air pollution exposure within an urban area. To evaluate the extent to which satellite data from the Ozone Monitoring Instrument (OMI) can resolve urban-scale gradients in ground-level nitrogen dioxide (NO2) within a large urban area, we compared estimates of surface NO2 concentrations derived from OMI measurements and US EPA ambient monitoring stations. OMI, aboard NASA's Aura satellite, provides daily afternoon (˜13:30 local time) measurements of NO2 tropospheric column abundance. We used scaling factors (surface-to-column ratios) to relate satellite column measurements to ground-level concentrations. We compared 4138 sets of paired data for 25 monitoring stations in the South Coast Air Basin of California for all of 2005. OMI measurements include more data gaps than the ground monitors (60% versus 5% of available data, respectively), owing to cloud contamination and imposed limits on pixel size. The spatial correlation between OMI columns and corrected in situ measurements is strong (r = 0.93 for annual average data), indicating that the within-urban spatial signature of surface NO2 is well resolved by the satellite sensor. Satellite-based surface estimates employing scaling factors from an urban model provide a reliable measure (annual mean bias: -13%; seasonal mean bias: <1% [spring] to -22% [fall]) of fine-scale surface NO2. We also find that OMI provides good spatial density in the study region (average area [km2] per measurement: 730 for the satellite sensor vs. 1100 for the monitors). Our findings indicate that satellite observations of NO2 from the OMI sensor provide a reliable measure of spatial variability in ground-level NO2 exposure for a large urban area.

Evaluation of accessible mineral surface areas for improved prediction of mineral reaction rates in porous media

NASA Astrophysics Data System (ADS)

Beckingham, Lauren E.; Steefel, Carl I.; Swift, Alexander M.; Voltolini, Marco; Yang, Li; Anovitz, Lawrence M.; Sheets, Julia M.; Cole, David R.; Kneafsey, Timothy J.; Mitnick, Elizabeth H.; Zhang, Shuo; Landrot, Gautier; Ajo-Franklin, Jonathan B.; DePaolo, Donald J.; Mito, Saeko; Xue, Ziqiu

2017-05-01

The rates of mineral dissolution reactions in porous media are difficult to predict, in part because of a lack of understanding of mineral reactive surface area in natural porous media. Common estimates of mineral reactive surface area used in reactive transport models for porous media are typically ad hoc and often based on average grain size, increased to account for surface roughness or decreased by several orders of magnitude to account for reduced surface reactivity of field as opposed to laboratory samples. In this study, accessible mineral surface areas are determined for a sample from the reservoir formation at the Nagaoka pilot CO2 injection site (Japan) using a multi-scale image analysis based on synchrotron X-ray microCT, SEM QEMSCAN, XRD, SANS, and FIB-SEM. This analysis not only accounts for accessibility of mineral surfaces to macro-pores, but also accessibility through connected micro-pores in smectite, the most abundant clay mineral in this sample. While the imaging analysis reveals that most of the micro- and macro-pores are well connected, some pore regions are unconnected and thus inaccessible to fluid flow and diffusion. To evaluate whether mineral accessible surface area accurately reflects reactive surface area a flow-through core experiment is performed and modeled at the continuum scale. The core experiment is performed under conditions replicating the pilot site and the evolution of effluent solutes in the aqueous phase is tracked. Various reactive surface area models are evaluated for their ability to capture the observed effluent chemistry, beginning with parameter values determined as a best fit to a disaggregated sediment experiment (Beckingham et al., 2016) described previously. Simulations that assume that all mineral surfaces are accessible (as in the disaggregated sediment experiment) over-predict the observed mineral reaction rates, suggesting that a reduction of RSA by a factor of 10-20 is required to match the core flood experimental data. While the fit of the effluent chemistry (and inferred mineral dissolution rates) greatly improve when the pore-accessible mineral surface areas are used, it was also necessary to include highly reactive glass phases to match the experimental observations, in agreement with conclusions from the disaggregated sediment experiment. It is hypothesized here that the 10-20 reduction in reactive surface areas based on the limited pore accessibility of reactive phases in core flood experiment may be reasonable for poorly sorted and cemented sediments like those at the Nagaoka site, although this reflects pore rather than larger scale heterogeneity.

Surface charging of a crater near lunar terminator

NASA Astrophysics Data System (ADS)

Anuar, A. K.

2017-05-01

Past lunar missions have shown the presence of dust particles in the lunar exosphere. These particles originate from lunar surface and are due to the charging of lunar surface by the solar wind and solar UV flux. Near the lunar terminator region, the low conductivity of the surface and small scale variations in surface topology could cause the surface to charge to different surface potentials. This paper simulates the variation of surface potential for a crater located in the lunar terminator regions using Spacecraft Plasma Interaction Software (SPIS). SPIS employs particle in cell method to simulate the motion of solar wind particles and photoelectrons. Lunar crater has been found to create mini-wake which affects both electron and ion density and causes small scale potential differences. Simulation results show potential difference of 300 V between sunlit area and shadowed area which creates suitable condition for dust levitation to occur.

Estimation of potential loss of two pesticides in runoff in Fillmore County, Minnesota using a field-scale process-based model and a geographic information system

USGS Publications Warehouse

Capel, P.D.; Zhang, H.

2000-01-01

In assessing the occurrence, behavior, and effects of agricultural chemicals in surface water, the scales of study (i.e., watershed, county, state, and regional areas) are usually much larger than the scale of agricultural fields, where much of the understanding of processes has been developed. Field-scale areas are characterized by relatively homogeneous conditions. The combination of process-based simulation models and geographic information system technology can be used to help extend our understanding of field processes to water-quality concerns at larger scales. To demonstrate this, the model "Groundwater Loading Effects of Agricultural Management Systems" was used to estimate the potential loss of two pesticides (atrazine and permethrin) in runoff to surface water in Fillmore County in southeastern Minnesota. The county was divided into field-scale areas on the basis of a 100 m by 100 m grid, and the influences of soil type and surface topography on the potential losses of the two pesticides in runoff was evaluated for each individual grid cell. The results could be used for guidance for agricultural management and regulatory decisions, for planning environmental monitoring programs, and as an educational tool for the public.

Large-scale experimental technology with remote sensing in land surface hydrology and meteorology

NASA Technical Reports Server (NTRS)

Brutsaert, Wilfried; Schmugge, Thomas J.; Sellers, Piers J.; Hall, Forrest G.

1988-01-01

Two field experiments to study atmospheric and land surface processes and their interactions are summarized. The Hydrologic-Atmospheric Pilot Experiment, which tested techniques for measuring evaporation, soil moisture storage, and runoff at scales of about 100 km, was conducted over a 100 X 100 km area in France from mid-1985 to early 1987. The first International Satellite Land Surface Climatology Program field experiment was conducted in 1987 to develop and use relationships between current satellite measurements and hydrologic, climatic, and biophysical variables at the earth's surface and to validate these relationships with ground truth. This experiment also validated surface parameterization methods for simulation models that describe surface processes from the scale of vegetation leaves up to scales appropriate to satellite remote sensing.

Allometric scaling of microbial fuel cells and stacks: The lifeform case for scale-up

NASA Astrophysics Data System (ADS)

Greenman, John; Ieropoulos, Ioannis A.

2017-07-01

This case study reports for the first time on the comparison between allometric scaling of lifeforms and scale-up of microbial fuel cell entities; enlarging individual units in volume, footprint and electrode surface area but also multiplying a static size/footprint and electrode surface area to scale-up by stacking. A study published in 2010 by DeLong et al. showed for the first time that Kleiber's law does not apply uniformly to all lifeforms, and that in fact growth rate for prokaryotes is superlinear, for protists is linear and for metazoa is sublinear. The current study, which is utilising data from previous experiments, is showing for the first time that for individual MFC units, which are enlarged, growth rate/power is sublinear, whereas for stacks this is superlinear.

INTERFRAGMENTARY SURFACE AREA AS AN INDEX OF COMMINUTION SEVERITY IN CORTICAL BONE IMPACT

PubMed Central

Beardsley, Christina L.; Anderson, Donald D.; Marsh, J. Lawrence; Brown, Thomas D.

2008-01-01

Summary A monotonic relationship is expected between energy absorption and fracture surface area generation for brittle solids, based on fracture mechanics principles. It was hypothesized that this relationship is demonstrable in bone, to the point that on a continuous scale, comminuted fractures created with specific levels of energy delivery could be discriminated from one another. Using bovine cortical bone segments in conjunction with digital image analysis of CT fracture data, the surface area freed by controlled impact fracture events was measured. The results demonstrated a statistically significant (p<0.0001) difference in measured de novo surface area between three specimen groups, over a range of input energies from 0.423 to 0.702 J/g. Local material properties were also incorporated into these measurements via CT Hounsfield intensities. This study confirms that comminution severity of bone fractures can indeed be measured on a continuous scale, based on energy absorption. This lays a foundation for similar assessments in human injuries. PMID:15885492

SIMULATED IMPACTS OF SMALL-SCALE SPATIAL DISTRIBUTION OF IMPERVIOUS AREA ON RUNOFF RESPONSE OF FIELD-SCALE CATCHMENTS

EPA Science Inventory

Impervious surface is known to negatively affect catchment hydrology through both its extent and spatial distribution. In this study, we empirically quantify via model simulations the impacts of different configurations of impervious surface on watershed response to rainfall. An ...

Deriving Surface NO2 Mixing Ratios from DISCOVER-AQ ACAM Observations: A Method to Assess Surface NO2 Spatial Variability

NASA Astrophysics Data System (ADS)

Silverman, M. L.; Szykman, J.; Chen, G.; Crawford, J. H.; Janz, S. J.; Kowalewski, M. G.; Lamsal, L. N.; Long, R.

2015-12-01

Studies have shown that satellite NO2 columns are closely related to ground level NO2 concentrations, particularly over polluted areas. This provides a means to assess surface level NO2 spatial variability over a broader area than what can be monitored from ground stations. The characterization of surface level NO2 variability is important to understand air quality in urban areas, emissions, health impacts, photochemistry, and to evaluate the performance of chemical transport models. Using data from the NASA DISCOVER-AQ campaign in Baltimore/Washington we calculate NO2 mixing ratios from the Airborne Compact Atmospheric Mapper (ACAM), through four different methods to derive surface concentration from column measurements. High spectral resolution lidar (HSRL) mixed layer heights, vertical P3B profiles, and CMAQ vertical profiles are used to scale ACAM vertical column densities. The derived NO2 mixing ratios are compared to EPA ground measurements taken at Padonia and Edgewood. We find similar results from scaling with HSRL mixed layer heights and normalized P3B vertical profiles. The HSRL mixed layer heights are then used to scale ACAM vertical column densities across the DISCOVER-AQ flight pattern to assess spatial variability of NO2 over the area. This work will help define the measurement requirements for future satellite instruments.

Surface premelting/recrystallization governing the collapse of open-cell nanoporous Cu via thermal annealing.

PubMed

Wang, L; Zhang, X M; Deng, L; Tang, J F; Xiao, S F; Deng, H Q; Hu, W Y

2018-06-04

We systematically investigate the collapse of a set of open-cell nanoporous Cu (np-Cu) materials with the same porosity and shape but different specific surface areas, during thermal annealing, by performing large-scale molecular dynamics simulations. Two mechanisms govern the collapse of np-Cu. One is direct surface premelting, facilitating the collapse of np-Cu, when the specific surface area is less than a critical value (∼2.38 nm-1). The other is recrystallization followed by surface premelting, accelerating the sloughing of ligaments and the annihilation of voids, when the critical specific surface area is exceeded. Surface premelting results from surface reconstruction by prompting localized "disordering" and "chaos" on the surface, and the melting temperature reduces linearly with the increase of the specific surface area. Recrystallization is followed by surface premelting as the melting temperature is below the supercooling point, where a liquid is unstable and instantaneously recrystallizes.

Flight paths of seabirds soaring over the ocean surface enable measurement of fine-scale wind speed and direction.

PubMed

Yonehara, Yoshinari; Goto, Yusuke; Yoda, Ken; Watanuki, Yutaka; Young, Lindsay C; Weimerskirch, Henri; Bost, Charles-André; Sato, Katsufumi

2016-08-09

Ocean surface winds are an essential factor in understanding the physical interactions between the atmosphere and the ocean. Surface winds measured by satellite scatterometers and buoys cover most of the global ocean; however, there are still spatial and temporal gaps and finer-scale variations of wind that may be overlooked, particularly in coastal areas. Here, we show that flight paths of soaring seabirds can be used to estimate fine-scale (every 5 min, ∼5 km) ocean surface winds. Fine-scale global positioning system (GPS) positional data revealed that soaring seabirds flew tortuously and ground speed fluctuated presumably due to tail winds and head winds. Taking advantage of the ground speed difference in relation to flight direction, we reliably estimated wind speed and direction experienced by the birds. These bird-based wind velocities were significantly correlated with wind velocities estimated by satellite-borne scatterometers. Furthermore, extensive travel distances and flight duration of the seabirds enabled a wide range of high-resolution wind observations, especially in coastal areas. Our study suggests that seabirds provide a platform from which to measure ocean surface winds, potentially complementing conventional wind measurements by covering spatial and temporal measurement gaps.

Flight paths of seabirds soaring over the ocean surface enable measurement of fine-scale wind speed and direction

PubMed Central

Yonehara, Yoshinari; Goto, Yusuke; Yoda, Ken; Watanuki, Yutaka; Young, Lindsay C.; Weimerskirch, Henri; Bost, Charles-André; Sato, Katsufumi

2016-01-01

Ocean surface winds are an essential factor in understanding the physical interactions between the atmosphere and the ocean. Surface winds measured by satellite scatterometers and buoys cover most of the global ocean; however, there are still spatial and temporal gaps and finer-scale variations of wind that may be overlooked, particularly in coastal areas. Here, we show that flight paths of soaring seabirds can be used to estimate fine-scale (every 5 min, ∼5 km) ocean surface winds. Fine-scale global positioning system (GPS) positional data revealed that soaring seabirds flew tortuously and ground speed fluctuated presumably due to tail winds and head winds. Taking advantage of the ground speed difference in relation to flight direction, we reliably estimated wind speed and direction experienced by the birds. These bird-based wind velocities were significantly correlated with wind velocities estimated by satellite-borne scatterometers. Furthermore, extensive travel distances and flight duration of the seabirds enabled a wide range of high-resolution wind observations, especially in coastal areas. Our study suggests that seabirds provide a platform from which to measure ocean surface winds, potentially complementing conventional wind measurements by covering spatial and temporal measurement gaps. PMID:27457932

Residues of organochlorine pesticides in surface soil and raw foods from rural areas of the Republic of Tajikistan

EPA Science Inventory

The central Asian Republic of Tajikistan has been an area of extensive historical agricultural pesticide use as well as large scale burials of obsolete banned chlorinated insecticides. The current investigation was a four year study of legacy organochlorine pesticides in surface ...

Internal variability of fine-scale components of meteorological fields in extended-range limited-area model simulations with atmospheric and surface nudging

NASA Astrophysics Data System (ADS)

Separovic, Leo; Husain, Syed Zahid; Yu, Wei

2015-09-01

Internal variability (IV) in dynamical downscaling with limited-area models (LAMs) represents a source of error inherent to the downscaled fields, which originates from the sensitive dependence of the models to arbitrarily small modifications. If IV is large it may impose the need for probabilistic verification of the downscaled information. Atmospheric spectral nudging (ASN) can reduce IV in LAMs as it constrains the large-scale components of LAM fields in the interior of the computational domain and thus prevents any considerable penetration of sensitively dependent deviations into the range of large scales. Using initial condition ensembles, the present study quantifies the impact of ASN on IV in LAM simulations in the range of fine scales that are not controlled by spectral nudging. Four simulation configurations that all include strong ASN but differ in the nudging settings are considered. In the fifth configuration, grid nudging of land surface variables toward high-resolution surface analyses is applied. The results show that the IV at scales larger than 300 km can be suppressed by selecting an appropriate ASN setup. At scales between 300 and 30 km, however, in all configurations, the hourly near-surface temperature, humidity, and winds are only partly reproducible. Nudging the land surface variables is found to have the potential to significantly reduce IV, particularly for fine-scale temperature and humidity. On the other hand, hourly precipitation accumulations at these scales are generally irreproducible in all configurations, and probabilistic approach to downscaling is therefore recommended.

Radar characteristics of Viking 1 landing sites

USGS Publications Warehouse

Tyler, G.L.; Campbell, D.B.; Downs, G.S.; Green, R.R.; Moore, H.J.

1976-01-01

Radar observations of Mars at centimeter wavelengths in May, June, and July 1976 provided estimates of surface roughness and reflectivity in three potential landing areas for Viking 1. Surface roughness is characterized by the distribution of surface landing slopes or tilts on lateral scales of the order of 1 to 10 meters; measurements of surface reflectivity are indicators of bulk surface density in the uppermost few centimeters. By these measures, the Viking 1 landing site at 47.5??W, 22.4??N is rougher than the martian average, although it may be near the martian average for elevations accessible to Viking, and is estimated to be near the Mars average in reflectivity. The AINW site at the center of Chryse Planitia, 43.5??W, 23.4??N, may be an area of anomalous radar characteristics, indicative of extreme, small-scale roughness, very low surface density, or a combination of these two characteristics. Low signal-to-noise ratio observations of the original Chryse site at 34??W, 19.5??N indicate that that area is at least twice as rough as the Mars average.

Detection of submicron scale cracks and other surface anomalies using positron emission tomography

DOEpatents

Cowan, Thomas E.; Howell, Richard H.; Colmenares, Carlos A.

2004-02-17

Detection of submicron scale cracks and other mechanical and chemical surface anomalies using PET. This surface technique has sufficient sensitivity to detect single voids or pits of sub-millimeter size and single cracks or fissures of millimeter size; and single cracks or fissures of millimeter-scale length, micrometer-scale depth, and nanometer-scale length, micrometer-scale depth, and nanometer-scale width. This technique can also be applied to detect surface regions of differing chemical reactivity. It may be utilized in a scanning or survey mode to simultaneously detect such mechanical or chemical features over large interior or exterior surface areas of parts as large as about 50 cm in diameter. The technique involves exposing a surface to short-lived radioactive gas for a time period, removing the excess gas to leave a partial monolayer, determining the location and shape of the cracks, voids, porous regions, etc., and calculating the width, depth, and length thereof. Detection of 0.01 mm deep cracks using a 3 mm detector resolution has been accomplished using this technique.

Surface roughness manifestations of deep-seated landslide processes

NASA Astrophysics Data System (ADS)

Booth, A. M.; Roering, J. J.; Lamb, M. P.

2012-12-01

In many mountainous drainage basins, deep-seated landslides evacuate large volumes of sediment from small surface areas, leaving behind a strong topographic signature that sets landscape roughness over a range of spatial scales. At long spatial wavelengths of hundreds to thousands of meters, landslides tend to inhibit channel incision and limit topographic relief, effectively smoothing the topography at this length scale. However, at short spatial wavelengths on the order of meters, deformation of deep-seated landslides generates surface roughness that allows expert mappers or automated algorithms to distinguish landslides from the surrounding terrain. Here, we directly connect the characteristic spatial wavelengths and amplitudes of this fine scale surface roughness to the underlying landslide deformation processes. We utilize the two-dimensional wavelet transform with high-resolution, airborne LiDAR-derived digital elevation models to systematically document the characteristic length scales and amplitudes of different kinematic units within slow moving earthflows, a common type of deep-seated landslide. In earthflow source areas, discrete slumped blocks generate high surface roughness, reflecting an extensional deformation regime. In earthflow transport zones, where material translates with minimal surface deformation, roughness decreases as other surface processes quickly smooth short wavelength features. In earthflow depositional toes, compression folds and thrust faults again increase short wavelength surface roughness. When an earthflow becomes inactive, roughness in all of these kinematic zones systematically decreases with time, allowing relative dating of earthflow deposits. We also document how each of these roughness expressions depends on earthflow velocity, using sub-pixel change detection software (COSI-Corr) and pairs of orthorectified aerial photographs to determine spatially extensive landslide surface displacements. In source areas, the wavelength of slumped blocks tends to correlate with velocity as predicted by a simple sliding block model, but the amplitude is insensitive to velocity, suggesting that landslide depth rather than velocity sets this characteristic block amplitude. In both transport zones and depositional toes, the amplitude of the surface roughness is higher where the longitudinal gradient in velocity is higher, confirming that differential movement generates and maintains this fine scale roughness.

Nano- to Formation-Scale Estimates of Mineral-Specific Reactive Surface Area

NASA Astrophysics Data System (ADS)

Cole, D. R.; Swift, A.; Sheets, J.; Anovitz, L. M.

2017-12-01

Predictions of changes in fluid composition, coupled with the evolution of the solid matrix, include the generation and testing of reactive transport models. However, translating a heterogeneous natural system into physical and chemical model parameters, including the critical but poorly-constrained metric of fluid-accessible surface area, continues to challenge Earth scientists. Studies of carbon storage capacity, permeability, rock strain due to mineral dissolution and precipitation, or the prediction of rock evolution through diagenesis and weathering each consider macroscale outcomes of processes that often are critically impacted by rock surface geometry at the nanoscale. The approach taken here is to consider the whole vertical extent of a saline reservoir and then to address two questions. First, what is the accessible surface area for each major mineral, and for all adjacent pore sizes from <2 nm on up, within each major lithofacies in that formation? Second, with the formation thus divided into units of analysis, parameterized, and placed into geologic context, what constraints can be placed on reactive surface area as a function of mineral composition? A complex sandstone covering a substantial fraction of the quartz-K-feldspar-illite ternary is selected and mineral-specific surface area quantified using neutron scattering, nitrogen and mercury porosimetry, multi-signal high-resolution mineral mapping, and other techniques. For neutron scattering, scale-specific pore geometries enable more accurate translation of volume into surface area. By applying this workflow to all end-member lithologies of this reservoir formation, equations and maps of surface area as a function of position on a quartz-feldspar-clay ternary plot are developed for each major mineral. Results from this work therefore advance our ability to parameterize models not just for the particular formation studied, but for similar geologic units as well.

Field-scale moisture estimates using COSMOS sensors: a validation study with temporary networks and leaf-area-indices

USDA-ARS?s Scientific Manuscript database

The Cosmic-ray Soil Moisture Observing System (COSMOS) is a new and innovative method for estimating surface and near surface soil moisture at large (~700 m) scales. This system accounts for liquid water within its measurement volume. Many of the sites used in the early validation of the system had...

Influence of liquid surface area on hydrogen sulfide oxidation during micro-aeration in dairy manure digesters

USDA-ARS?s Scientific Manuscript database

The specific objectives of this study were to evaluate headspace aeration for reducing hydrogen sulfide levels in low cost plug flow digesters, and to characterize the relationship between the liquid surface area and hydrogen sulfide oxidation rates. Experiments with replicate field scale plug flow ...

Multi-method, multi-scale geophysical observations in the Obsidian Pool Thermal Area, Yellowstone National Park

NASA Astrophysics Data System (ADS)

Holbrook, W. S.; Carr, B.; Pasquet, S.; Sims, K. W. W.; Dickey, K.

2016-12-01

Despite the prominence of Yellowstone as the world's most active hydrothermal province, relatively little is known about the plumbing systems that link deeper hydrothermal fluids to the charismatic hot springs, geysers and mud pots at the surface. We present the results of a multi-method, multi-scale geophysical investigation of the Obsidian Pool Thermal Area (OPTA) in Yellowstone National Park. OPTA hosts acid-sulfate hot springs and mud pots with relatively low pH. We present the results of seismic refraction, electrical resistivity, time-domain EM (TEM), soil conductivity meter (EMI), and GPR data acquired in July 2016. There is a strong contrast in physical properties in the upper 50 m of the subsurface between the low-lying hydrothermal area and surrounding hills: the hydrothermal area has much lower seismic velocities ( 1 km/s vs 3 km/s) and electrical resistivity ( 20 ohm-m vs 300 ohm-m). A prominent zone of very low resistivity (<10 ohm-m) exists at about 20 m depth beneath all hydrothermal features. Poisson's ratio, calculated from P-wave refraction tomography and surface wave inversions, shows low values beneath the "frying pan," where gas is emerging in small fumaroles, suggesting that Poisson's ratio is an effective "gas detector" in hydrothermal areas. Near-surface resistivity mapped from EMI shows a strong correlation with hydrothermal areas previously mapped by heat flow, with areas of high heat flow generally having low resistivity near the surface. Two exceptions are (1) the "frying pan," which shows a central area of high resistivity (corresponding to escaping gas) surrounding by a halo of low resistivity, and (2) a broad area of low resistivity connecting the hydrothermal centers to the lake, which may be clay deposits. TEM data penetrate up to 200 m in depth and suggest that a reservoir of hydrothermal fluids may underlie the entire area, including beneath the forested hills, at depths greater than 100 m, but that they rise toward the surface in a 100-m-wide area just west of the frying pan. Our results show that synoptic, multi-scale geophysical measurements can place important constraints on the subsurface pathways of hydrothermal waters and gas.

The physical basis of glacier volume-area scaling

USGS Publications Warehouse

Bahr, D.B.; Meier, M.F.; Peckham, S.D.

1997-01-01

Ice volumes are known for only a few of the roughly 160,000 glaciers worldwide but are important components of many climate and sea level studies which require water flux estimates. A scaling analysis of the mass and momentum conservation equations shows that glacier volumes can be related by a power law to more easily observed glacier surface areas. The relationship requires four closure choices for the scaling behavior of glacier widths, slopes, side drag and mass balance. Reasonable closures predict a volume-area scaling exponent which is consistent with observations, giving a physical and practical basis for estimating ice volumes. Glacier volume is insensitive to perturbations in the mass balance scaling, but changes in average accumulation area ratios reflect significant changes in the scaling of both mass balance and ice volume. Copyright 1997 by the American Geophysical Union.

Respiratory and olfactory turbinal size in canid and arctoid carnivorans.

PubMed

Green, Patrick A; Van Valkenburgh, Blaire; Pang, Benison; Bird, Deborah; Rowe, Timothy; Curtis, Abigail

2012-12-01

Within the nasal cavity of mammals is a complex scaffold of paper-thin bones that function in respiration and olfaction. Known as turbinals, the bones greatly enlarge the surface area available for conditioning inspired air, reducing water loss, and improving olfaction. Given their functional significance, the relative development of turbinal bones might be expected to differ among species with distinct olfactory, thermoregulatory and/or water conservation requirements. Here we explore the surface area of olfactory and respiratory turbinals relative to latitude and diet in terrestrial Caniformia, a group that includes the canid and arctoid carnivorans (mustelids, ursids, procyonids, mephitids, ailurids). Using high-resolution computed tomography x-ray scans, we estimated respiratory and olfactory turbinal surface area and nasal chamber volume from three-dimensional virtual models of skulls. Across the Caniformia, respiratory surface area scaled isometrically with estimates of body size and there was no significant association with climate, as estimated by latitude. Nevertheless, one-on-one comparisons of sister taxa suggest that arctic species may have expanded respiratory turbinals. Olfactory surface area scaled isometrically among arctoids, but showed positive allometry in canids, reflecting the fact that larger canids, all of which are carnivorous, had relatively greater olfactory surface areas. In addition, among the arctoids, large carnivorous species such as the polar bear (Ursus maritimus) and wolverine (Gulo gulo) also displayed enlarged olfactory turbinals. More omnivorous caniform species that feed on substantial quantities of non-vertebrate foods had less expansive olfactory turbinals. Because large carnivorous species hunt widely dispersed prey, an expanded olfactory turbinal surface area may improve a carnivore's ability to detect prey over great distances using olfactory cues. © 2012 The Authors. Journal of Anatomy © 2012 Anatomical Society.

Respiratory and olfactory turbinal size in canid and arctoid carnivorans

PubMed Central

Green, Patrick A; Valkenburgh, Blaire; Pang, Benison; Bird, Deborah; Rowe, Timothy; Curtis, Abigail

2012-01-01

Within the nasal cavity of mammals is a complex scaffold of paper-thin bones that function in respiration and olfaction. Known as turbinals, the bones greatly enlarge the surface area available for conditioning inspired air, reducing water loss, and improving olfaction. Given their functional significance, the relative development of turbinal bones might be expected to differ among species with distinct olfactory, thermoregulatory and/or water conservation requirements. Here we explore the surface area of olfactory and respiratory turbinals relative to latitude and diet in terrestrial Caniformia, a group that includes the canid and arctoid carnivorans (mustelids, ursids, procyonids, mephitids, ailurids). Using high-resolution computed tomography x-ray scans, we estimated respiratory and olfactory turbinal surface area and nasal chamber volume from three-dimensional virtual models of skulls. Across the Caniformia, respiratory surface area scaled isometrically with estimates of body size and there was no significant association with climate, as estimated by latitude. Nevertheless, one-on-one comparisons of sister taxa suggest that arctic species may have expanded respiratory turbinals. Olfactory surface area scaled isometrically among arctoids, but showed positive allometry in canids, reflecting the fact that larger canids, all of which are carnivorous, had relatively greater olfactory surface areas. In addition, among the arctoids, large carnivorous species such as the polar bear (Ursus maritimus) and wolverine (Gulo gulo) also displayed enlarged olfactory turbinals. More omnivorous caniform species that feed on substantial quantities of non-vertebrate foods had less expansive olfactory turbinals. Because large carnivorous species hunt widely dispersed prey, an expanded olfactory turbinal surface area may improve a carnivore's ability to detect prey over great distances using olfactory cues. PMID:23035637

Nitrogen-doped hierarchical lamellar porous carbon synthesized from the fish scale as support material for platinum nanoparticle electrocatalyst toward the oxygen reduction reaction.

PubMed

Liu, Haijing; Cao, Yinliang; Wang, Feng; Huang, Yaqin

2014-01-22

Novel hierarchical lamellar porous carbon (HLPC) with high BET specific surface area of 2730 m(2) g(-1) and doped by nitrogen atoms has been synthesized from the fish scale without any post-synthesis treatment, and applied to support the platinum (Pt) nanoparticle (NP) catalysts (Pt/HLPC). The Pt NPs could be highly dispersed on the porous surface of HLPC with a narrow size distribution centered at ca. 2.0 nm. The results of the electrochemical analysis reveal that the electrochemical active surface area (ECSA) of Pt/HLPC is larger than the Pt NP electrocatalyst supported on the carbon black (Pt/Vulcan XC-72). Compared with the Pt/Vulcan XC-72, the Pt/HLPC exhibits larger current density, lower overpotential, and enhanced catalytic activity toward the oxygen reduction reaction (ORR) through the direct four-electron pathway. The improved catalytic activity is mainly attributed to the high BET specific surface area, hierarchical porous structures and the nitrogen-doped surface property of HLPC, indicating the superiority of HLPC as a promising support material for the ORR electrocatalysts.

Research Advances on Radiation Transfer Modeling and Inversion for Multi-Scale Land Surface Remote Sensing

NASA Astrophysics Data System (ADS)

Liu, Q.

2011-09-01

At first, research advances on radiation transfer modeling on multi-scale remote sensing data are presented: after a general overview of remote sensing radiation transfer modeling, several recent research advances are presented, including leaf spectrum model (dPROS-PECT), vegetation canopy BRDF models, directional thermal infrared emission models(TRGM, SLEC), rugged mountains area radiation models, and kernel driven models etc. Then, new methodologies on land surface parameters inversion based on multi-source remote sensing data are proposed. The land surface Albedo, leaf area index, temperature/emissivity, and surface net radiation etc. are taken as examples. A new synthetic land surface parameter quantitative remote sensing product generation system is designed and the software system prototype will be demonstrated. At last, multi-scale field experiment campaigns, such as the field campaigns in Gansu and Beijing, China will be introduced briefly. The ground based, tower based, and airborne multi-angular measurement system have been built to measure the directional reflectance, emission and scattering characteristics from visible, near infrared, thermal infrared and microwave bands for model validation and calibration. The remote sensing pixel scale "true value" measurement strategy have been designed to gain the ground "true value" of LST, ALBEDO, LAI, soil moisture and ET etc. at 1-km2 for remote sensing product validation.

Scale-dependent entrainment velocity and scale-independent net entrainment in a turbulent axisymmetric jet

NASA Astrophysics Data System (ADS)

Philip, Jimmy; Mistry, Dhiren; Dawson, James; Marusic, Ivan

2016-11-01

The net entrainment in a jet is the product of the mean surface area (S ̲) and the mean entrainment velocity, V ̲ S ̲ , where, V ̲ = αUc with α the entrainment coefficient and Uc the mean centreline velocity. Instantaneously, however, entrainment velocity (v) at a point on the interface is the difference between the interface and the fluid velocities, and the total entrainment ∫ vds = VS , where S is the corrugated interface surface area and V the area averaged entrainment velocity. Using time-resolved multi-scale PIV/PLIF measurements of velocity and scalar in an axisymmetric jet at Re = 25000 , we evaluate V and S directly at the smallest resolved scales, and by filtering the data at different scales (Δ) we find their multi-scales counterparts, VΔ and SΔ. We show that V ̲ S ̲ =VΔ SΔ = V S , independent of the scale. Furthermore, S is found to have a fractal dimension D3 2 . 32 +/- 0 . 1 . Independently, we find that VΔ Δ 0 . 31 , indicating increasing entrainment velocity with increasing length scale. This is consistent with a constant net entrainment across scales, and suggests α as a scale-dependent quantity. Engineering and Physical Sciences Research Council (research Grant No. EP/I005879/1), David Crighton Fellowship from the DAMTP, Univ of Cambridge, and the Australian Research Council.

City landscape changes effects on land surface temperature in Bucharest metropolitan area

NASA Astrophysics Data System (ADS)

Savastru, Dan M.; Zoran, Maria A.; Savastru, Roxana S.; Dida, Adrian I.

2017-10-01

This study investigated the influences of city land cover changes and extreme climate events on land surface temperature in relationship with several biophysical variables in Bucharest metropolitan area of Romania through satellite and in-situ monitoring data. Remote sensing data from IKONOS, Landsat TM/ETM+ and time series MODIS Terra/Aqua and NOAA AVHRR sensors have been used to assess urban land cover- temperature interactions over 2000 - 2016 period. Time series Thermal InfraRed (TIR) satellite remote sensing data in synergy with meteorological data (air temperatureAT, precipitations, wind, solar radiation, etc.) were applied mainly for analyzing land surface temperature (LST) pattern and its relationship with surface landscape characteristics, assessing urban heat island (UHI), and relating urban land cover temperatures (LST). The land surface temperature, a key parameter for urban thermal characteristics analysis, was also analyzed in relation with the Normalized Difference Vegetation Index (NDVI) at city level. Results show that in the metropolitan area ratio of impervious surface in Bucharest increased significantly during investigated period, the intensity of urban heat island and heat wave events being most significant. The correlation analyses revealed that, at the pixel-scale, LST and AT possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at metropolitan scale respectively. The NDVI was significantly correlated with precipitation. The spatial average air temperatures in urban test areas rise with the expansion of the urban size.

The Forest Canopy as a Temporally and Spatially Dynamic Ecosystem: Preliminary Results of Biomass Scaling and Habitat Use from a Case Study in Large Eastern White Pines (Pinus Strobus)

NASA Astrophysics Data System (ADS)

Martin, J.; Laughlin, M. M.; Olson, E.

2017-12-01

Canopy processes can be viewed at many scales and through many lenses. Fundamentally, we may wish to start by treating each canopy as a unique surface, an ecosystem unto itself. By doing so, we can may make some important observations that greatly influence our ability to scale canopies to landscape, regional and global scales. This work summarizes an ongoing endeavor to quantify various canopy level processes on individual old and large Eastern white pine trees (Pinus strobus). Our work shows that these canopies contain complex structures that vary with height and as the tree ages. This phenomenon complicates the allometric scaling of these large trees using standard methods, but detailed measurements from within the canopy provided a method to constrain scaling equations. We also quantified how these canopies change and respond to canopy disturbance, and documented disproportionate variation of growth compared to the lower stem as the trees develop. Additionally, the complex shape and surface area allow these canopies to act like ecosystems themselves; despite being relatively young and more commonplace when compared to the more notable canopies of the tropics and the Pacific Northwestern US. The white pines of these relatively simple, near boreal forests appear to house various species including many lichens. The lichen species can cover significant portions of the canopy surface area (which may be only 25 to 50 years old) and are a sizable source of potential nitrogen additions to the soils below, as well as a modulator to hydrologic cycles by holding significant amounts of precipitation. Lastly, the combined complex surface area and focused verticality offers important habitat to numerous animal species, some of which are quite surprising.

Tin doped indium oxide anodes with artificially controlled nano-scale roughness using segregated Ag nanoparticles for organic solar cells

NASA Astrophysics Data System (ADS)

Kim, Hyo-Joong; Ko, Eun-Hye; Noh, Yong-Jin; Na, Seok-In; Kim, Han-Ki

2016-09-01

Nano-scale surface roughness in transparent ITO films was artificially formed by sputtering a mixed Ag and ITO layer and wet etching of segregated Ag nanoparticles from the surface of the ITO film. Effective removal of self-segregated Ag particles from the grain boundaries and surface of the crystalline ITO film led to a change in only the nano-scale surface morphology of ITO film without changes in the sheet resistance and optical transmittance. A nano-scale rough surface of the ITO film led to an increase in contact area between the hole transport layer and the ITO anode, and eventually increased the hole extraction efficiency in the organic solar cells (OSCs). The heterojunction OSCs fabricated on the ITO anode with a nano-scale surface roughness exhibited a higher power conversion efficiency of 3.320%, than that (2.938%) of OSCs made with the reference ITO/glass. The results here introduce a new method to improve the performance of OSCs by simply modifying the surface morphology of the ITO anodes.

An upscaled rate law for magnesite dissolution in heterogeneous porous media

NASA Astrophysics Data System (ADS)

Wen, Hang; Li, Li

2017-08-01

Spatial heterogeneity in natural subsurface systems governs water fluxes and residence time in reactive zones and therefore determines effective rates of mineral dissolution. Extensive studies have documented mineral dissolution rates in natural systems, although a general rate law has remain elusive. Here we fill this gap by answering two questions: (1) how and to what extent does spatial heterogeneity affect water residence time and effectively-dissolving surface area? (2) what is the upscaled rate law that quantifies effective dissolution rates in natural, heterogeneous media? With data constraints from experimental work, 240 Monte-Carlo numerical experiments of magnesite dissolution within quartz matrix were run with spatial distributions characterized by a range of permeability variance σ2lnκ (0.5-6.0) and correlation length (2-50 cm). Although the total surface area and global residence time (τa) are the same in all experiments, the water fluxes through reactive magnesite zones varies between 0.7 and 72.8% of the total water fluxes. Highly heterogeneous media with large σ2lnκ and long λ divert water mostly into non-reactive preferential flow paths, therefore bypassing and minimizing flow in low permeability magnesite zones. As a result, the water residence time in magnesite zones (i.e., reactive residence time τa,r) is long and magnesite dissolution quickly reaches local equilibrium, which leads to small effective surface area and low dissolution rates. Magnesite dissolution rates in heterogeneous media vary from 2.7 to 100% of the rates in the equivalent homogeneous media, with effectively-dissolving surface area varying from 0.18 to 6.83 m2 (out of 51.71 m2 total magnesite surface area). Based on 240 numerical experiments and 45 column experiments, a general upscaled rate law in heterogeneous media, RMgCO3,ht =kAe,hm(1 - exp(-τa/τa,r))α, was derived to quantify effective dissolution rates. The dissolution rates in heterogeneous media are a function of the rate constants k being those measured under well-mixed conditions, effective surface area in equivalent homogeneous media Ae,hm, and the heterogeneity factor (1 - exp(-τa/τa,r))α. The heterogeneity factor quantify heterogeneity effects and depends on the relative magnitude of global residence time (τa) and reactive residence time (τa,r), as well as the shape factor α(= 5 σlnκ2) of the gamma distribution for reactive residence times. Exponential forms of rate laws have been used at the micro-scale describing direct interactions among water and mineral surface, and at the catchment scale describing weathering rates and concentration-discharge relationships. These observations highlight the key role of mineral-water contact time in determining dissolution rates at different scales. This work also emphasizes the importance of critical interfaces between reactive and non-reactive zones as determined by the details of spatial patterns and effective surface area as a scaling factor that quantifies dissolution rates in heterogeneous media across scales.

Sensitivity of Regional Climate to Deforestation in the Amazon Basin

NASA Technical Reports Server (NTRS)

Eltahir, Elfatih A. B.; Bras, Rafael L.

1994-01-01

The deforestation results in several adverse effect on the natural environment. The focus of this paper is on the effects of deforestation on land-surface processes and regional climate of the Amazon basin. In general, the effect of deforestation on climate are likely to depend on the scale of the defrosted area. In this study, we are interested in the effects due to deforestation of areas with a scale of about 250 km. Hence, a meso-scale climate model is used in performing numerical experiments on the sensitivity of regional climate to deforestation of areas with that size. It is found that deforestation results in less net surface radiation, less evaporation, less rainfall, and warmer surface temperature. The magnitude of the of the change in temperature is of the order 0.5 C, the magnitudes of the changes in the other variables are of the order of IO%. In order to verify some of he results of the numerical experiments, the model simulations of net surface radiation are compared to recent observations of net radiation over cleared and undisturbed forest in the Amazon. The results of the model and the observations agree in the following conclusion: the difference in net surface radiation between cleared and undisturbed forest is, almost, equally partioned between net solar radiation and net long-wave radiation. This finding contributes to our understanding of the basic physics in the deforestation problem.

Mapping daily evapotranspiration at field scales over rainfed and irrigated agricultural areas using remote sensing data fusion

USDA-ARS?s Scientific Manuscript database

A continuous monitoring of daily evapotranspiration (ET) at field scale can be achieved by combining thermal infrared remote sensing data information from multiple satellite platforms. Here, an integrated approach to field scale ET mapping is described, combining multi-scale surface energy balance e...

Area-averaged evapotranspiration over a heterogeneous land surface: aggregation of multi-point EC flux measurements with a high-resolution land-cover map and footprint analysis

NASA Astrophysics Data System (ADS)

Xu, Feinan; Wang, Weizhen; Wang, Jiemin; Xu, Ziwei; Qi, Yuan; Wu, Yueru

2017-08-01

The determination of area-averaged evapotranspiration (ET) at the satellite pixel scale/model grid scale over a heterogeneous land surface plays a significant role in developing and improving the parameterization schemes of the remote sensing based ET estimation models and general hydro-meteorological models. The Heihe Watershed Allied Telemetry Experimental Research (HiWATER) flux matrix provided a unique opportunity to build an aggregation scheme for area-averaged fluxes. On the basis of the HiWATER flux matrix dataset and high-resolution land-cover map, this study focused on estimating the area-averaged ET over a heterogeneous landscape with footprint analysis and multivariate regression. The procedure is as follows. Firstly, quality control and uncertainty estimation for the data of the flux matrix, including 17 eddy-covariance (EC) sites and four groups of large-aperture scintillometers (LASs), were carefully done. Secondly, the representativeness of each EC site was quantitatively evaluated; footprint analysis was also performed for each LAS path. Thirdly, based on the high-resolution land-cover map derived from aircraft remote sensing, a flux aggregation method was established combining footprint analysis and multiple-linear regression. Then, the area-averaged sensible heat fluxes obtained from the EC flux matrix were validated by the LAS measurements. Finally, the area-averaged ET of the kernel experimental area of HiWATER was estimated. Compared with the formerly used and rather simple approaches, such as the arithmetic average and area-weighted methods, the present scheme is not only with a much better database, but also has a solid grounding in physics and mathematics in the integration of area-averaged fluxes over a heterogeneous surface. Results from this study, both instantaneous and daily ET at the satellite pixel scale, can be used for the validation of relevant remote sensing models and land surface process models. Furthermore, this work will be extended to the water balance study of the whole Heihe River basin.

Sub-kilometer Numerical Weather Prediction in complex urban areas

NASA Astrophysics Data System (ADS)

Leroyer, S.; Bélair, S.; Husain, S.; Vionnet, V.

2013-12-01

A Sub-kilometer atmospheric modeling system with grid-spacings of 2.5 km, 1 km and 250 m and including urban processes is currently being developed at the Meteorological Service of Canada (MSC) in order to provide more accurate weather forecasts at the city scale. Atmospheric lateral boundary conditions are provided with the 15-km Canadian Regional Deterministic Prediction System (RDPS). Surface physical processes are represented with the Town Energy Balance (TEB) model for the built-up covers and with the Interactions between the Surface, Biosphere, and Atmosphere (ISBA) land surface model for the natural covers. In this study, several research experiments over large metropolitan areas and using observational networks at the urban scale are presented, with a special emphasis on the representation of local atmospheric circulations and their impact on extreme weather forecasting. First, numerical simulations are performed over the Vancouver metropolitan area during a summertime Intense Observing Period (IOP of 14-15 August 2008) of the Environmental Prediction in Canadian Cities (EPiCC) observational network. The influence of the horizontal resolution on the fine-scale representation of the sea-breeze development over the city is highlighted (Leroyer et al., 2013). Then severe storms cases occurring in summertime within the Greater Toronto Area (GTA) are simulated. In view of supporting the 2015 PanAmerican and Para-Pan games to be hold in GTA, a dense observational network has been recently deployed over this region to support model evaluations at the urban and meso scales. In particular, simulations are conducted for the case of 8 July 2013 when exceptional rainfalls were recorded. Leroyer, S., S. Bélair, J. Mailhot, S.Z. Husain, 2013: Sub-kilometer Numerical Weather Prediction in an Urban Coastal Area: A case study over the Vancouver Metropolitan Area, submitted to Journal of Applied Meteorology and Climatology.

Pore-scale study of multiphase reactive transport in fibrous electrodes of vanadium redox flow batteries

DOE PAGES

Chen, Li; He, YaLing; Tao, Wen -Quan; ...

2017-07-21

The electrode of a vanadium redox flow battery generally is a carbon fibre-based porous medium, in which important physicochemical processes occur. In this work, pore-scale simulations are performed to study complex multiphase flow and reactive transport in the electrode by using the lattice Boltzmann method (LBM). Four hundred fibrous electrodes with different fibre diameters and porosities are reconstructed. Both the permeability and diffusivity of the reconstructed electrodes are predicted and compared with empirical relationships in the literature. Reactive surface area of the electrodes is also evaluated and it is found that existing empirical relationship overestimates the reactive surface under lowermore » porosities. Further, a pore-scale electrochemical reaction model is developed to study the effects of fibre diameter and porosity on electrolyte flow, V II/V III transport, and electrochemical reaction at the electrolyte-fibre surface. Finally, evolution of bubble cluster generated by the side reaction is studied by adopting a LB multiphase flow model. Effects of porosity, fibre diameter, gas saturation and solid surface wettability on average bubble diameter and reduction of reactive surface area due to coverage of bubbles on solid surface are investigated in detail. It is found that gas coverage ratio is always lower than that adopted in the continuum model in the literature. Furthermore, the current pore-scale studies successfully reveal the complex multiphase flow and reactive transport processes in the electrode, and the simulation results can be further upscaled to improve the accuracy of the current continuum-scale models.« less

Darkening effect on AZ31B magnesium alloy surface induced by nanosecond pulse Nd:YAG laser

NASA Astrophysics Data System (ADS)

Guan, Y. C.; Zhou, W.; Zheng, H. Y.; Li, Z. L.

2013-09-01

Permanent darkening effect was achieved on surface of AZ31B Mg alloy irradiated with nanosecond pulse Nd:YAG laser, and special attention was made to examine how surface structure as well as oxidation affect the darkening effect. Experiments were carried out to characterize morphological evolution and chemical composition of the irradiated areas by optical reflection spectrometer, Talysurf surface profiler, SEM, EDS, and XPS. The darkening effect was found to be occurred at the surface under high laser energy. Optical spectra showed that the induced darkening surface was uniform over the spectral range from 200 nm to 1100 nm. SEM and surface profiler showed that surface morphology of darkening areas consisted of large number of micron scale cauliflower-like clusters and protruding particles. EDS and XPS showed that compared to non-irradiated area, oxygen content at the darkening areas increased significantly. It was proposed a mechanism that involved trapping of light in the surface morphology and chemistry variation of irradiated areas to explain the laser-induced darkening effect on AZ31B Mg alloy.

Body mass scaling of passive oxygen diffusion in endotherms and ectotherms

PubMed Central

Gillooly, James F.; Gomez, Juan Pablo; Mavrodiev, Evgeny V.; Rong, Yue; McLamore, Eric S.

2016-01-01

The area and thickness of respiratory surfaces, and the constraints they impose on passive oxygen diffusion, have been linked to differences in oxygen consumption rates and/or aerobic activity levels in vertebrates. However, it remains unclear how respiratory surfaces and associated diffusion rates vary with body mass across vertebrates, particularly in relation to the body mass scaling of oxygen consumption rates. Here we address these issues by first quantifying the body mass dependence of respiratory surface area and respiratory barrier thickness for a diversity of endotherms (birds and mammals) and ectotherms (fishes, amphibians, and reptiles). Based on these findings, we then use Fick’s law to predict the body mass scaling of oxygen diffusion for each group. Finally, we compare the predicted body mass dependence of oxygen diffusion to that of oxygen consumption in endotherms and ectotherms. We find that the slopes and intercepts of the relationships describing the body mass dependence of passive oxygen diffusion in these two groups are statistically indistinguishable from those describing the body mass dependence of oxygen consumption. Thus, the area and thickness of respiratory surfaces combine to match oxygen diffusion capacity to oxygen consumption rates in both air- and water-breathing vertebrates. In particular, the substantially lower oxygen consumption rates of ectotherms of a given body mass relative to those of endotherms correspond to differences in oxygen diffusion capacity. These results provide insights into the long-standing effort to understand the structural attributes of organisms that underlie the body mass scaling of oxygen consumption. PMID:27118837

Body mass scaling of passive oxygen diffusion in endotherms and ectotherms.

PubMed

Gillooly, James F; Gomez, Juan Pablo; Mavrodiev, Evgeny V; Rong, Yue; McLamore, Eric S

2016-05-10

The area and thickness of respiratory surfaces, and the constraints they impose on passive oxygen diffusion, have been linked to differences in oxygen consumption rates and/or aerobic activity levels in vertebrates. However, it remains unclear how respiratory surfaces and associated diffusion rates vary with body mass across vertebrates, particularly in relation to the body mass scaling of oxygen consumption rates. Here we address these issues by first quantifying the body mass dependence of respiratory surface area and respiratory barrier thickness for a diversity of endotherms (birds and mammals) and ectotherms (fishes, amphibians, and reptiles). Based on these findings, we then use Fick's law to predict the body mass scaling of oxygen diffusion for each group. Finally, we compare the predicted body mass dependence of oxygen diffusion to that of oxygen consumption in endotherms and ectotherms. We find that the slopes and intercepts of the relationships describing the body mass dependence of passive oxygen diffusion in these two groups are statistically indistinguishable from those describing the body mass dependence of oxygen consumption. Thus, the area and thickness of respiratory surfaces combine to match oxygen diffusion capacity to oxygen consumption rates in both air- and water-breathing vertebrates. In particular, the substantially lower oxygen consumption rates of ectotherms of a given body mass relative to those of endotherms correspond to differences in oxygen diffusion capacity. These results provide insights into the long-standing effort to understand the structural attributes of organisms that underlie the body mass scaling of oxygen consumption.

Local variance for multi-scale analysis in geomorphometry.

PubMed

Drăguţ, Lucian; Eisank, Clemens; Strasser, Thomas

2011-07-15

Increasing availability of high resolution Digital Elevation Models (DEMs) is leading to a paradigm shift regarding scale issues in geomorphometry, prompting new solutions to cope with multi-scale analysis and detection of characteristic scales. We tested the suitability of the local variance (LV) method, originally developed for image analysis, for multi-scale analysis in geomorphometry. The method consists of: 1) up-scaling land-surface parameters derived from a DEM; 2) calculating LV as the average standard deviation (SD) within a 3 × 3 moving window for each scale level; 3) calculating the rate of change of LV (ROC-LV) from one level to another, and 4) plotting values so obtained against scale levels. We interpreted peaks in the ROC-LV graphs as markers of scale levels where cells or segments match types of pattern elements characterized by (relatively) equal degrees of homogeneity. The proposed method has been applied to LiDAR DEMs in two test areas different in terms of roughness: low relief and mountainous, respectively. For each test area, scale levels for slope gradient, plan, and profile curvatures were produced at constant increments with either resampling (cell-based) or image segmentation (object-based). Visual assessment revealed homogeneous areas that convincingly associate into patterns of land-surface parameters well differentiated across scales. We found that the LV method performed better on scale levels generated through segmentation as compared to up-scaling through resampling. The results indicate that coupling multi-scale pattern analysis with delineation of morphometric primitives is possible. This approach could be further used for developing hierarchical classifications of landform elements.

Local variance for multi-scale analysis in geomorphometry

PubMed Central

Drăguţ, Lucian; Eisank, Clemens; Strasser, Thomas

2011-01-01

Increasing availability of high resolution Digital Elevation Models (DEMs) is leading to a paradigm shift regarding scale issues in geomorphometry, prompting new solutions to cope with multi-scale analysis and detection of characteristic scales. We tested the suitability of the local variance (LV) method, originally developed for image analysis, for multi-scale analysis in geomorphometry. The method consists of: 1) up-scaling land-surface parameters derived from a DEM; 2) calculating LV as the average standard deviation (SD) within a 3 × 3 moving window for each scale level; 3) calculating the rate of change of LV (ROC-LV) from one level to another, and 4) plotting values so obtained against scale levels. We interpreted peaks in the ROC-LV graphs as markers of scale levels where cells or segments match types of pattern elements characterized by (relatively) equal degrees of homogeneity. The proposed method has been applied to LiDAR DEMs in two test areas different in terms of roughness: low relief and mountainous, respectively. For each test area, scale levels for slope gradient, plan, and profile curvatures were produced at constant increments with either resampling (cell-based) or image segmentation (object-based). Visual assessment revealed homogeneous areas that convincingly associate into patterns of land-surface parameters well differentiated across scales. We found that the LV method performed better on scale levels generated through segmentation as compared to up-scaling through resampling. The results indicate that coupling multi-scale pattern analysis with delineation of morphometric primitives is possible. This approach could be further used for developing hierarchical classifications of landform elements. PMID:21779138

Tracking fine-scale seasonal evolution of surface water extent in Central Alaska and the Canadian Shield

NASA Astrophysics Data System (ADS)

Cooley, S. W.; Smith, L. C.; Pitcher, L. H.; Pavelsky, T.; Topp, S.

2017-12-01

Quantifying spatial and temporal variability in surface water storage at high latitudes is critical for assessing environmental sensitivity to climate change. Traditionally the tradeoff between high spatial and high temporal resolution space-borne optical imagery has limited the ability to track fine-scale changes in surface water extent. However, the recent launch of hundreds of earth-imaging CubeSats by commercial satellite companies such as Planet opens up new possibilities for monitoring surface water from space. In this study we present a comparison of seasonal evolution of surface water extent in two study areas with differing geologic, hydrologic and permafrost regimes, namely, the Yukon Flats in Central Alaska and the Canadian Shield north of Yellowknife, N.W.T. Using near-daily 3m Planet CubeSat imagery, we track individual lake surface area from break-up to freeze-up during summer 2017 and quantify the spatial and temporal variability in inundation extent. We validate our water delineation method and inundation extent time series using WorldView imagery, coincident in situ lake shoreline mapping and pressure transducer data for 19 lakes in the Northwest Territories and Alaska collected during the NASA Arctic Boreal Vulnerability Experiment (ABoVE) 2017 field campaign. The results of this analysis demonstrate the value of CubeSat imagery for dynamic surface water research particularly at high latitudes and illuminate fine-scale drivers of cold regions surface water extent.

Porous silicon structures with high surface area/specific pore size

DOEpatents

Northrup, M.A.; Yu, C.M.; Raley, N.F.

1999-03-16

Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific pore size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gases in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased pressure for thermopneumatic actuation of integrated membranes. Examples that benefit from specific pore sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters. 9 figs.

Porous silicon structures with high surface area/specific pore size

DOEpatents

Northrup, M. Allen; Yu, Conrad M.; Raley, Norman F.

1999-01-01

Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific pore size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gasses in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased pressure for thermopneumatic actuation of integrated membranes. Examples that benefit from specific pore sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters.

Estimating Long Term Surface Soil Moisture in the GCIP Area From Satellite Microwave Observations

NASA Technical Reports Server (NTRS)

Owe, Manfred; deJeu, Vrije; VandeGriend, Adriaan A.

2000-01-01

Soil moisture is an important component of the water and energy balances of the Earth's surface. Furthermore, it has been identified as a parameter of significant potential for improving the accuracy of large-scale land surface-atmosphere interaction models. However, accurate estimates of surface soil moisture are often difficult to make, especially at large spatial scales. Soil moisture is a highly variable land surface parameter, and while point measurements are usually accurate, they are representative only of the immediate site which was sampled. Simple averaging of point values to obtain spatial means often leads to substantial errors. Since remotely sensed observations are already a spatially averaged or areally integrated value, they are ideally suited for measuring land surface parameters, and as such, are a logical input to regional or larger scale land process models. A nine-year database of surface soil moisture is being developed for the Central United States from satellite microwave observations. This region forms much of the GCIP study area, and contains most of the Mississippi, Rio Grande, and Red River drainages. Daytime and nighttime microwave brightness temperatures were observed at a frequency of 6.6 GHz, by the Scanning Multichannel Microwave Radiometer (SMMR), onboard the Nimbus 7 satellite. The life of the SMMR instrument spanned from Nov. 1978 to Aug. 1987. At 6.6 GHz, the instrument provided a spatial resolution of approximately 150 km, and an orbital frequency over any pixel-sized area of about 2 daytime and 2 nighttime passes per week. Ground measurements of surface soil moisture from various locations throughout the study area are used to calibrate the microwave observations. Because ground measurements are usually only single point values, and since the time of satellite coverage does not always coincide with the ground measurements, the soil moisture data were used to calibrate a regional water balance for the top 1, 5, and 10 cm surface layers in order to interpolate daily surface moisture values. Such a climate-based approach is often more appropriate for estimating large-area spatially averaged soil moisture because meteorological data are generally more spatially representative than isolated point measurements of soil moisture. Vegetation radiative transfer characteristics, such as the canopy transmissivity, were estimated from vegetation indices such as the Normalized Difference Vegetation Index (NDVI) and the 37 GHz Microwave Polarization Difference Index (MPDI). Passive microwave remote sensing presents the greatest potential for providing regular spatially representative estimates of surface soil moisture at global scales. Real time estimates should improve weather and climate modelling efforts, while the development of historical data sets will provide necessary information for simulation and validation of long-term climate and global change studies.

Scaling between reanalyses and high-resolution land-surface modelling in mountainous areas - enabling better application and testing of reanalyses in heterogeneous environments

NASA Astrophysics Data System (ADS)

Gruber, S.; Fiddes, J.

2013-12-01

In mountainous topography, the difference in scale between atmospheric reanalyses (typically tens of kilometres) and relevant processes and phenomena near the Earth surface, such as permafrost or snow cover (meters to tens of meters) is most obvious. This contrast of scales is one of the major obstacles to using reanalysis data for the simulation of surface phenomena and to confronting reanalyses with independent observation. At the example of modelling permafrost in mountain areas (but simple to generalise to other phenomena and heterogeneous environments), we present and test methods against measurements for (A) scaling atmospheric data from the reanalysis to the ground level and (B) smart sampling of the heterogeneous landscape in order to set up a lumped model simulation that represents the high-resolution land surface. TopoSCALE (Part A, see http://dx.doi.org/10.5194/gmdd-6-3381-2013) is a scheme, which scales coarse-grid climate fields to fine-grid topography using pressure level data. In addition, it applies necessary topographic corrections e.g. those variables required for computation of radiation fields. This provides the necessary driving fields to the LSM. Tested against independent ground data, this scheme has been shown to improve the scaling and distribution of meteorological parameters in complex terrain, as compared to conventional methods, e.g. lapse rate based approaches. TopoSUB (Part B, see http://dx.doi.org/10.5194/gmd-5-1245-2012) is a surface pre-processor designed to sample a fine-grid domain (defined by a digital elevation model) along important topographical (or other) dimensions through a clustering scheme. This allows constructing a lumped model representing the main sources of fine-grid variability and applying a 1D LSM efficiently over large areas. Results can processed to derive (i) summary statistics at coarse-scale re-analysis grid resolution, (ii) high-resolution data fields spatialized to e.g., the fine-scale digital elevation model grid, or (iii) validation products for locations at which measurements exist, only. The ability of TopoSUB to approximate results simulated by a 2D distributed numerical LSM at a factor of ~10,000 less computations is demonstrated by comparison of 2D and lumped simulations. Successful application of the combined scheme in the European Alps is reported and based on its results, open issues for future research are outlined.

The production of premixed flame surface area in turbulent shear flow

NASA Technical Reports Server (NTRS)

Trouve, A.

1993-01-01

In the present work, we use three-dimensional Direct Numerical Simulation (DNS) of premixed flames in turbulent shear flow to characterize the effect of a mean shear motion on flame surface production. The shear is uniform in the unburnt gas, and simulations are performed for different values of the mean shear rate, S. The data base is then used to estimate and compare the different terms appearing in the Sigma-equation as a function of S. The analysis gives in particular the relative weights f the turbulent flow and mean flow components, a(sub T) and A(sub T), of the flame surface production term. This comparison indicates whether the dominant effects of a mean flow velocity gradient on flame surface area are implicit and scale with the modified turbulent flow parameters, kappa and epsilon, or explicit and scale directly with the rate of deformation.

Multiscale Simulations of ALD in Cross Flow Reactors

DOE PAGES

Yanguas-Gil, Angel; Libera, Joseph A.; Elam, Jeffrey W.

2014-08-13

In this study, we have developed a multiscale simulation code that allows us to study the impact of surface chemistry on the coating of large area substrates with high surface area/high aspect-ratio features. Our code, based on open-source libraries, takes advantage of the ALD surface chemistry to achieve an extremely efficient two-way coupling between reactor and feature length scales, and it can provide simulated quartz crystal microbalance and mass spectrometry data at any point of the reactor. By combining experimental surface characterization with simple analysis of growth profiles in a tubular cross flow reactor, we are able to extract amore » minimal set of reactions to effectively model the surface chemistry, including the presence of spurious CVD, to evaluate the impact of surface chemistry on the coating of large, high surface area substrates.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Li; He, YaLing; Tao, Wen -Quan

The electrode of a vanadium redox flow battery generally is a carbon fibre-based porous medium, in which important physicochemical processes occur. In this work, pore-scale simulations are performed to study complex multiphase flow and reactive transport in the electrode by using the lattice Boltzmann method (LBM). Four hundred fibrous electrodes with different fibre diameters and porosities are reconstructed. Both the permeability and diffusivity of the reconstructed electrodes are predicted and compared with empirical relationships in the literature. Reactive surface area of the electrodes is also evaluated and it is found that existing empirical relationship overestimates the reactive surface under lowermore » porosities. Further, a pore-scale electrochemical reaction model is developed to study the effects of fibre diameter and porosity on electrolyte flow, V II/V III transport, and electrochemical reaction at the electrolyte-fibre surface. Finally, evolution of bubble cluster generated by the side reaction is studied by adopting a LB multiphase flow model. Effects of porosity, fibre diameter, gas saturation and solid surface wettability on average bubble diameter and reduction of reactive surface area due to coverage of bubbles on solid surface are investigated in detail. It is found that gas coverage ratio is always lower than that adopted in the continuum model in the literature. Furthermore, the current pore-scale studies successfully reveal the complex multiphase flow and reactive transport processes in the electrode, and the simulation results can be further upscaled to improve the accuracy of the current continuum-scale models.« less

Research Advances on Radiation Transfer Modeling and Inversion for Multi-scale Land Surface Remote Sensing

NASA Astrophysics Data System (ADS)

Liu, Q.; Li, J.; Du, Y.; Wen, J.; Zhong, B.; Wang, K.

2011-12-01

As the remote sensing data accumulating, it is a challenge and significant issue how to generate high accurate and consistent land surface parameter product from the multi source remote observation and the radiation transfer modeling and inversion methodology are the theoretical bases. In this paper, recent research advances and unresolved issues are presented. At first, after a general overview, recent research advances on multi-scale remote sensing radiation transfer modeling are presented, including leaf spectrum model, vegetation canopy BRDF models, directional thermal infrared emission models, rugged mountains area radiation models, and kernel driven models etc. Then, new methodologies on land surface parameters inversion based on multi-source remote sensing data are proposed, taking the land surface Albedo, leaf area index, temperature/emissivity, and surface net radiation as examples. A new synthetic land surface parameter quantitative remote sensing product generation system is suggested and the software system prototype will be demonstrated. At last, multi-scale field experiment campaigns, such as the field campaigns in Gansu and Beijing, China are introduced briefly. The ground based, tower based, and airborne multi-angular measurement system have been built to measure the directional reflectance, emission and scattering characteristics from visible, near infrared, thermal infrared and microwave bands for model validation and calibration. The remote sensing pixel scale "true value" measurement strategy have been designed to gain the ground "true value" of LST, ALBEDO, LAI, soil moisture and ET etc. at 1-km2 for remote sensing product validation.

Evaluation of a Moderate Resolution, Satellite-Based Impervious Surface Map Using an Independent, High-Resolution Validation Dataset

EPA Science Inventory

Given the relatively high cost of mapping impervious surfaces at regional scales, substantial effort is being expended in the development of moderate-resolution, satellite-based methods for estimating impervious surface area (ISA). To rigorously assess the accuracy of these data ...

Estimating Surface and Subsurface Ice Abundance on Mercury Using a Thermophysical Model

NASA Astrophysics Data System (ADS)

Rubanenko, L.; Mazarico, E.; Neumann, G. A.; Paige, D. A.

2016-12-01

The small obliquity of the Moon and Mercury causes some topographic features near their poles to cast permanent shadows for geologic time periods. In the past, these permanently shadowed regions (PSRs) were found to have low enough temperatures to trap surface and subsurface water ice. On Mercury, high normal albedo is correlated with maximum temperatures <100 m and high radar backscatter, possibly indicating the presence of surface ice. Areas with slightly higher maximum temperatures were measured to have a decreased albedo, postulated to contain of organic materials overlaying buried ice. We evaluate this theory by employing a thermophysical model that considers insolation, scattering, thermal emissions and subsurface conduction. We model the area fraction of surface and subsurface cold-traps on realistic topography at scales of ˜500 m , recorded by the Mercury Laster Altimeter (MLA) on board the MErcury Surface, Space ENviroment, GEochemistry and Ranging (MESSENGER) spacecraft. At smaller scales, below the instrument threshold, we consider a statistical description of the surface assuming a Gaussian slope distribution. Using the modeled cold-trap area fraction we calculate the expected surface albedo and compare it to MESSENGER's near-infrared surface reflectance data. Last, we apply our model to other airless small-obliquity planetary bodies such as the Moon and Ceres in order to explain other correlations between the maximum temperature and normal albedo.

The cold and atmospheric-pressure air surface barrier discharge plasma for large-area sterilization applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Dacheng; Department of Aeronautics, Fujian Key Laboratory for Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005; Zhao Di

2011-04-18

This letter reports a stable air surface barrier discharge device for large-area sterilization applications at room temperature. This design may result in visually uniform plasmas with the electrode area scaled up (or down) to the required size. A comparison for the survival rates of Escherichia coli from air, N{sub 2} and O{sub 2} surface barrier discharge plasmas is presented, and the air surface plasma consisting of strong filamentary discharges can efficiently kill Escherichia coli. Optical emission measurements indicate that reactive species such as O and OH generated in the room temperature air plasmas play a significant role in the sterilizationmore » process.« less

Continental-scale distributions of dust-associated bacteria and fungi

PubMed Central

Barberán, Albert; Ladau, Joshua; Pollard, Katherine S.; Menninger, Holly L.; Dunn, Robert R.; Fierer, Noah

2015-01-01

It has been known for centuries that microorganisms are ubiquitous in the atmosphere, where they are capable of long-distance dispersal. Likewise, it is well-established that these airborne bacteria and fungi can have myriad effects on human health, as well as the health of plants and livestock. However, we have a limited understanding of how these airborne communities vary across different geographic regions or the factors that structure the geographic patterns of near-surface microbes across large spatial scales. We collected dust samples from the external surfaces of ∼1,200 households located across the United States to understand the continental-scale distributions of bacteria and fungi in the near-surface atmosphere. The microbial communities were highly variable in composition across the United States, but the geographic patterns could be explained by climatic and soil variables, with coastal regions of the United States sharing similar airborne microbial communities. Although people living in more urbanized areas were not found to be exposed to distinct outdoor air microbial communities compared with those living in more rural areas, our results do suggest that urbanization leads to homogenization of the airborne microbiota, with more urban communities exhibiting less continental-scale geographic variability than more rural areas. These results provide our first insight into the continental-scale distributions of airborne microbes, which is information that could be used to identify likely associations between microbial exposures in outdoor air and incidences of disease in crops, livestock, and humans. PMID:25902536

A MULTIDISCIPLINARY APPROACH TO STORMWATER MANAGEMENT AT THE WATERSHED SCALE.

EPA Science Inventory

Stormwater runoff from extensive impervious surfaces in urban and suburban areas has led to human safety risks and stream ecosystem impairment, triggering an interest in watershed-scale retrofit stormwater management. Such stormwater management is of multidisciplinary relevance, ...

A MULTIDISCIPLINARY APPROACH TO STORMWATER MANAGEMENT AT THE catchment SCALE

EPA Science Inventory

Stormwater runoff from extensive impervious surfaces in urban and suburban areas has led to human safety risks and stream ecosystem impairment, triggering an interest in catchment-scale retrofit stormwater management. Such stormwater management is of multidisciplinary relevance, ...

RETROFIT STORMWATER MANAGEMENT: NAVIGATING MULTIDISCIPLINARY HURDLES AT THE WATERSHED SCALE

EPA Science Inventory

Stormwater runoff from extensive impervious surfaces in urban and suburban areas has led to human safety risks and stream ecosystem impairment, triggering an interest in watershed-scale retrofit stormwater management. Such stormwater management is of multidisciplinary relevance, ...

Positive effects of vegetation: urban heat island and green roofs.

PubMed

Susca, T; Gaffin, S R; Dell'osso, G R

2011-01-01

This paper attempts to evaluate the positive effects of vegetation with a multi-scale approach: an urban and a building scale. Monitoring the urban heat island in four areas of New York City, we have found an average of 2 °C difference of temperatures between the most and the least vegetated areas, ascribable to the substitution of vegetation with man-made building materials. At micro-scale, we have assessed the effect of surface albedo on climate through the use of a climatological model. Then, using the CO(2) equivalents as indicators of the impact on climate, we have compared the surface albedo, and the construction, replacement and use phase of a black, a white and a green roof. By our analyses, we found that both the white and the green roofs are less impactive than the black one; with the thermal resistance, the biological activity of plants and the surface albedo playing a crucial role. Copyright © 2011 Elsevier Ltd. All rights reserved.

Long-term studies on the effects of nonvolatile organic compounds on porous media surface areas.

PubMed

Khachikian, Crist S; Harmon, Thomas C

2002-01-01

This paper investigates the long-term behavior of porous media contaminated by nonvolatile organic compounds (NVOC) in terms of specific interfacial surface area. Specifically, a natural sand, Moffett sand (MS), was contaminated with naphthalene and the surface area was measured repeatedly over time using nitrogen adsorption-desorption techniques. A field-contaminated sand affected by lamp-black material (LB) from former manufactured gas plant operations was also studied. Lampblack is a carbonaceous skeleton containing polycyclic aromatic hydrocarbons (PAHs) and other hydrocarbons. It is hypothesized that soils contaminated by these types of chemicals will exhibit significantly less surface area than their clean counterparts. The surface areas for the contaminated MS samples increased toward their clean-MS values during the 700-h aging period, but achieved the clean values only after pentane extraction or heating at 60 degrees C. Heating at 50 degrees C failed to achieve a similar recovery of the clean-MS surface area value. Nonspecific mass loss tracked the increase in surface area as indirect evidence that naphthalene loss was the cause of the surface area increase. For the LB samples, aging at 100 degrees C produced a slight decrease in surface area and mass while aging at 250 degrees C caused the surface area to increase roughly threefold while the mass decreased by approximately 1%. These results suggest that, under moderate heating and over the time scale of this investigation, there is a redistribution of the complex contaminant mixture on the solid matrix. Greater temperatures remove mass more efficiently and therefore exhibited the surface area increase expected in this experiment.

Evaluating DEM conditioning techniques, elevation source data, and grid resolution for field-scale hydrological parameter extraction

NASA Astrophysics Data System (ADS)

Woodrow, Kathryn; Lindsay, John B.; Berg, Aaron A.

2016-09-01

Although digital elevation models (DEMs) prove useful for a number of hydrological applications, they are often the end result of numerous processing steps that each contains uncertainty. These uncertainties have the potential to greatly influence DEM quality and to further propagate to DEM-derived attributes including derived surface and near-surface drainage patterns. This research examines the impacts of DEM grid resolution, elevation source data, and conditioning techniques on the spatial and statistical distribution of field-scale hydrological attributes for a 12,000 ha watershed of an agricultural area within southwestern Ontario, Canada. Three conditioning techniques, including depression filling (DF), depression breaching (DB), and stream burning (SB), were examined. The catchments draining to each boundary of 7933 agricultural fields were delineated using the surface drainage patterns modeled from LiDAR data, interpolated to a 1 m, 5 m, and 10 m resolution DEMs, and from a 10 m resolution photogrammetric DEM. The results showed that variation in DEM grid resolution resulted in significant differences in the spatial and statistical distributions of contributing areas and the distributions of downslope flowpath length. Degrading the grid resolution of the LiDAR data from 1 m to 10 m resulted in a disagreement in mapped contributing areas of between 29.4% and 37.3% of the study area, depending on the DEM conditioning technique. The disagreements among the field-scale contributing areas mapped from the 10 m LiDAR DEM and photogrammetric DEM were large, with nearly half of the study area draining to alternate field boundaries. Differences in derived contributing areas and flowpaths among various conditioning techniques increased substantially at finer grid resolutions, with the largest disagreement among mapped contributing areas occurring between the 1 m resolution DB DEM and the SB DEM (37% disagreement) and the DB-DF comparison (36.5% disagreement in mapped areas). These results demonstrate that the decision to use one DEM conditioning technique over another, and the constraints of available DEM data resolution and source, can greatly impact the modeled surface drainage patterns at the scale of individual fields. This work has significance for applications that attempt to optimize best-management practices (BMPs) for reducing soil erosion and runoff contamination within agricultural watersheds.

Three Mars Years of Surface Albedo Changes Observed by the Mars Reconnaissance Orbiter MARCI Investigation

NASA Astrophysics Data System (ADS)

Bell, J. F.; Wellington, D. F.; Anderson, R. B.; Wolff, M. J.; Supulver, K. D.; Cantor, B. A.; Malin, M. C.

2012-12-01

The NASA Mars Reconnaissance Orbiter (MRO) spacecraft has been in its prime mapping orbit of the Red Planet since November 2006, a little over three Mars years. MRO's Mars Color Imager (MARCI) investigation has been acquiring wide-angle, approximately 1 km/pixel resolution multispectral images (from the UV to the short-wave near-IR) throughout the mission from the spacecraft's 300 km circular polar orbit. As of fall 2012, MARCI has acquired more than 25,000 image sequences, with its 180 degree field of view covering local solar times of approximately 15:00 +/- 2 hours at the equator. These images can be merged and map projected to provide near-global imaging coverage of Mars for almost every sol of the mission. These maps have been used to characterize and monitor changes in seasonal and interannual dust and water ice cloud opacity, growth and decay of local- to global-scale dust storms, and polar cap growth and recession. The data are also well-suited for studying small- to large-scale changes in surface albedo markings, important for understanding the nature of aeolian transport of dust and sand in the current Martian environment, as well as for modeling the radiative influence of the darker (warmer) or brighter (cooler) surface on local-scale atmospheric circulation and storm systems. We are using calibrated, map-projected, coregistered subsets of MARCI images to characterize and investigate surface albedo changes in a number of specific regions of interest, based on past Viking Orbiter, Hubble Space Telescope, and Mars Global Surveyor images of changing large-scale surface albedo patterns over recent decades, as well as recent surface missions that have characterized small-scale changes in surface albedo. Specific areas of study of large-scale changes include the dark areas Syrtis Major, Acidalia, Cimmeria, Sirenum, and Solis Lacus, and our initial focus areas for small-scale variations include regions in and around the landing sites of the Mars Exploration Rovers Spirit (Gusev crater) and Opportunity (Meridiani Planum), as well as Gale crater, the landing site for the Mars Science Laboratory rover Curiosity. Time-lapse animations of albedo changes in and around Gale crater, for example, reveal tens of km-scale changes in low albedo surface markings both within the crater (including near the rover's planned traverse path) as well as within the 500 km long low albedo wind streak south of the crater. Combined with morphologic, thermal inertia, and compositional/mineralogic constraints from other data sets, MARCI albedo variation measurements can help to constrain present rates of dust and sand transport in a variety of environments on Mars.

Hypogeal geological survey in the "Grotta del Re Tiberio" natural cave (Apennines, Italy): a valid tool for reconstructing the structural setting

NASA Astrophysics Data System (ADS)

Ghiselli, Alice; Merazzi, Marzio; Strini, Andrea; Margutti, Roberto; Mercuriali, Michele

2011-06-01

As karst systems are natural windows to the underground, speleology, combined with geological surveys, can be useful tools for helping understand the geological evolution of karst areas. In order to enhance the reconstruction of the structural setting in a gypsum karst area (Vena del Gesso, Romagna Apennines), a detailed analysis has been carried out on hypogeal data. Structural features (faults, fractures, tectonic foliations, bedding) have been mapped in the "Grotta del Re Tiberio" cave, in the nearby gypsum quarry tunnels and open pit benches. Five fracture systems and six fault systems have been identified. The fault systems have been further analyzed through stereographic projections and geometric-kinematic evaluations in order to reconstruct the relative chronology of these structures. This analysis led to the detection of two deformation phases. The results permitted linking of the hypogeal data with the surface data both at a local and regional scale. At the local scale, fracture data collected in the underground have been compared with previous authors' surface data coming from the quarry area. The two data sets show a very good correspondence, as every underground fracture system matches with one of the surface fracture system. Moreover, in the cave, a larger number of fractures belonging to each system could be mapped. At the regional scale, the two deformation phases detected can be integrated in the structural setting of the study area, thereby enhancing the tectonic interpretation of the area ( e.g., structures belonging to a new deformation phase, not reported before, have been identified underground). The structural detailed hypogeal survey has, thus, provided very useful data, both by integrating the existing information and revealing new data not detected at the surface. In particular, some small structures ( e.g., displacement markers and short fractures) are better preserved in the hypogeal environment than on the surface where the outcropping gypsum is more exposed to dissolution and recrystallization. The hypogeal geological survey, therefore, can be considered a powerful tool for integrating the surface and log data in order to enhance the reconstruction of the deformational history and to get a three-dimensional model of the bedrock in karst areas.

Imbibition of a textured surface decorated by short pillars with rounded edges.

PubMed

Obara, Noriko; Okumura, Ko

2012-08-01

Imbibition of micropatterned surfaces can have broad technological and fundamental implications for areas ranging from biomedical devices and fuel transport to writing with ink. Despite rapidly growing interests aimed at various applications, a fundamental physical understanding of the imbibition dynamics is still in its infancy. Recently, two simple scaling regimes for the dynamics have been established for a textured surface decorated with long pillars whose top and bottom edges are sharp. Here, we study the imbibition dynamics of textured surfaces decorated by short pillars with rounded edges, to find a different scaling regime. Interestingly, this regime originates not from the balance of two effects but from the hybrid balance of three effects. Furthermore, this scaling law can be universal or independent of the details of the texture geometry. We envision that this potentially universal scaling regime might be ubiquitous and will be useful in the handling and transportation of a small amount of liquid.

Urbanisation at multiple scales is associated with larger size and higher fecundity of an orb-weaving spider.

PubMed

Lowe, Elizabeth C; Wilder, Shawn M; Hochuli, Dieter F

2014-01-01

Urbanisation modifies landscapes at multiple scales, impacting the local climate and changing the extent and quality of natural habitats. These habitat modifications significantly alter species distributions and can result in increased abundance of select species which are able to exploit novel ecosystems. We examined the effect of urbanisation at local and landscape scales on the body size, lipid reserves and ovary weight of Nephila plumipes, an orb weaving spider commonly found in both urban and natural landscapes. Habitat variables at landscape, local and microhabitat scales were integrated to create a series of indexes that quantified the degree of urbanisation at each site. Spider size was negatively associated with vegetation cover at a landscape scale, and positively associated with hard surfaces and anthropogenic disturbance on a local and microhabitat scale. Ovary weight increased in higher socioeconomic areas and was positively associated with hard surfaces and leaf litter at a local scale. The larger size and increased reproductive capacity of N.plumipes in urban areas show that some species benefit from the habitat changes associated with urbanisation. Our results also highlight the importance of incorporating environmental variables from multiple scales when quantifying species responses to landscape modification.

Urbanisation at Multiple Scales Is Associated with Larger Size and Higher Fecundity of an Orb-Weaving Spider

PubMed Central

Lowe, Elizabeth C.; Wilder, Shawn M.; Hochuli, Dieter F.

2014-01-01

Urbanisation modifies landscapes at multiple scales, impacting the local climate and changing the extent and quality of natural habitats. These habitat modifications significantly alter species distributions and can result in increased abundance of select species which are able to exploit novel ecosystems. We examined the effect of urbanisation at local and landscape scales on the body size, lipid reserves and ovary weight of Nephila plumipes, an orb weaving spider commonly found in both urban and natural landscapes. Habitat variables at landscape, local and microhabitat scales were integrated to create a series of indexes that quantified the degree of urbanisation at each site. Spider size was negatively associated with vegetation cover at a landscape scale, and positively associated with hard surfaces and anthropogenic disturbance on a local and microhabitat scale. Ovary weight increased in higher socioeconomic areas and was positively associated with hard surfaces and leaf litter at a local scale. The larger size and increased reproductive capacity of N.plumipes in urban areas show that some species benefit from the habitat changes associated with urbanisation. Our results also highlight the importance of incorporating environmental variables from multiple scales when quantifying species responses to landscape modification. PMID:25140809

Scale issues in soil hydrology related to measurement and simulation: A case study in Colorado

USDA-ARS?s Scientific Manuscript database

State variables, such as soil water content (SWC), are typically measured or inferred at very small scales while being simulated at larger scales relevant to spatial management or hillslope areas. Thus there is an implicit spatial disparity that is often ignored. Surface runoff, on the other hand, ...

No Association between Cortical Gyrification or Intrinsic Curvature and Attention-deficit/Hyperactivity Disorder in Adolescents and Young Adults.

PubMed

Forde, Natalie J; Ronan, Lisa; Zwiers, Marcel P; Alexander-Bloch, Aaron F; Faraone, Stephen V; Oosterlaan, Jaap; Heslenfeld, Dirk J; Hartman, Catharina A; Buitelaar, Jan K; Hoekstra, Pieter J

2017-01-01

Magnetic resonance imaging (MRI) studies have highlighted subcortical, cortical, and structural connectivity abnormalities associated with attention-deficit/hyperactivity disorder (ADHD). Gyrification investigations of the cortex have been inconsistent and largely negative, potentially due to a lack of sensitivity of the previously used morphological parameters. The innovative approach of applying intrinsic curvature analysis, which is predictive of gyrification pattern, to the cortical surface applied herein allowed us greater sensitivity to determine whether the structural connectivity abnormalities thus far identified at a centimeter scale also occur at a millimeter scale within the cortical surface. This could help identify neurodevelopmental processes that contribute to ADHD. Structural MRI datasets from the NeuroIMAGE project were used [ n = 306 ADHD, n = 164 controls, and n = 148 healthy siblings of individuals with ADHD (age in years, mean(sd); 17.2 (3.4), 16.8 (3.2), and 17.7 (3.8), respectively)]. Reconstructions of the cortical surfaces were computed with FreeSurfer. Intrinsic curvature (taken as a marker of millimeter-scale surface connectivity) and local gyrification index were calculated for each point on the surface (vertex) with Caret and FreeSurfer, respectively. Intrinsic curvature skew and mean local gyrification index were extracted per region; frontal, parietal, temporal, occipital, cingulate, and insula. A generalized additive model was used to compare the trajectory of these measures between groups over age, with sex, scanner site, total surface area of hemisphere, and familiality accounted for. After correcting for sex, scanner site, and total surface area no group differences were found in the developmental trajectory of intrinsic curvature or local gyrification index. Despite the increased sensitivity of intrinsic curvature, compared to gyrification measures, to subtle morphological abnormalities of the cortical surface we found no milimeter-scale connectivity abnormalities associated with ADHD.

Spatial and Temporal Scales of Surface Water-Groundwater Interactions

NASA Astrophysics Data System (ADS)

Boano, F.

2016-12-01

The interfaces between surface water and groundwater (i.e., river and lake sediments) represent hotspots for nutrient transformation in watersheds. This intense biochemical activity stems from the peculiar physicochemical properties of these interface areas. Here, the exchange of water and nutrients between surface and subsurface environments creates an ecotone region that can support the presence of different microbial species responsible for nutrient transformation. Previous studies have elucidated that water exchange between rivers and aquifers is organized in a complex system of nested flow cells. Each cell entails a range of residence timescales spanning multiple order of magnitudes, providing opportunities for different biochemical reactions to occur. Physically-bases models represent useful tools to deal with the wide range of spatial and temporal scales that characterize surface-subsurface water exchange. This contribution will present insights about how hydrodynamic processes control scale organization for surface water - groundwater interactions. The specific focus will be the influence of exchange processes on microbial activity and nutrient transformation, discussing how groundwater flow at watershed scale controls flow conditions and hence constrain microbial reactions at much smaller scales.

Modeling Linkages Between Effective Impervious Surface and Urban Vegetation Productivity in Semi-arid Environments

NASA Astrophysics Data System (ADS)

Shields, C. A.; Tague, C.

2010-12-01

With a majority of the world's population now living in urban areas, the role of vegetation in urban ecosystems warrants increased attention. We address the question of how the fine scale (<5m) spatial arrangement of impervious surfaces affects water available to vegetation, which in turn can significantly impact the productivity of vegetation and uptake of C and N. To gain insight into how landscape features influence vegetation productivity, we use a coupled ecohydrogic model to estimate impacts of the amount and arrangement of impervious surfaces on vegetation water use. We use the model to explore how concepts from research in natural semi-arid ecosystems can be applied in the urban context. Ecological research in semi-arid ecosystems has shown that the arrangement of vegetated and bare surfaces plays a key role in regulating both runoff and ecosystem water use and productivity. Systems that include a mixture of bare and vegetated surfaces, for example, tend to show less runoff and more productivity than those with more homogeneous cover. In some instances, patchiness of bare and vegetated surfaces is more important than total vegetated area in determining rates of runoff and vegetation use of rainfall. In an urban context, impervious surfaces can be viewed as analogous to the bare surfaces present in undeveloped ecosystems. We consider not only the total impervious area (TIA), but also the effect of impervious area with a direct hydrologic connection to the stream network, effective impervious area (EIA). While increases in total impervious area (TIA) have been widely shown to impact catchment hydrology, the role of effective impervious area (EIA) has been less extensively studied. A consensus is emerging from the literature that EIA is as important or even more important than TIA as an indicator of catchment response to urbanization. Ecohydrologic models offer a tool to quantify the role of EIA on water availability and plant productivity and demonstrate the potential of urban areas to act as C or N sinks (and minimize the impacts such as increased storm runoff and degraded downstream water quality). We explore the relative roles of TIA and EIA on water availability and plant productivity in a semi-arid urban environment through a series of modeling exercises. The Regional HydroEcological Simulation System (RHESSys) is used to model a range of impervious surface and vegetation scenarios on a test hillslope in the Mission Creek catchment in Santa Barbara CA. Results indicate that reduced EIA can indeed act to mitigate the impact of TIA on water available to plants. We then implement a modification to the RHESSys model that incorporates patch scale estimates of EIA into simulations of the entire Mission Creek catchment, allowing us to quantify likely catchment-scale impacts of altering EIA.

Automated AFM for small-scale and large-scale surface profiling in CMP applications

NASA Astrophysics Data System (ADS)

Zandiatashbar, Ardavan; Kim, Byong; Yoo, Young-kook; Lee, Keibock; Jo, Ahjin; Lee, Ju Suk; Cho, Sang-Joon; Park, Sang-il

2018-03-01

As the feature size is shrinking in the foundries, the need for inline high resolution surface profiling with versatile capabilities is increasing. One of the important areas of this need is chemical mechanical planarization (CMP) process. We introduce a new generation of atomic force profiler (AFP) using decoupled scanners design. The system is capable of providing small-scale profiling using XY scanner and large-scale profiling using sliding stage. Decoupled scanners design enables enhanced vision which helps minimizing the positioning error for locations of interest in case of highly polished dies. Non-Contact mode imaging is another feature of interest in this system which is used for surface roughness measurement, automatic defect review, and deep trench measurement. Examples of the measurements performed using the atomic force profiler are demonstrated.

WNDCOM: estimating surface winds in mountainous terrain

Treesearch

Bill C. Ryan

1983-01-01

WNDCOM is a mathematical model for estimating surface winds in mountainous terrain. By following the procedures described, the sheltering and diverting effect of terrain, the individual components of the windflow, and the surface wind in remote mountainous areas can be estimated. Components include the contribution from the synoptic scale pressure gradient, the sea...

Green Infrastructure and Watershed-Scale Hydrology in Mixed Land Cover System

EPA Science Inventory

Urbanization results in replacement of pervious areas (e.g., vegetation, topsoil) with impervious surfaces such as roads, roofs, and parking lots, which cause reductions in interception, evapotranspiration, and infiltration, and increases in surface runoff (overland flow) and pol...

Wave Energy Prize MASK wave calibration data for the 1:20 scale testing at MASK

DOE Data Explorer

Driscoll, Rick

2017-05-08

Time series data, sensor layout, and wave calibration summaries for the wave height measurements for the 10 calibration sea states for the 1:20 scale testing of the Wave Energy Prize (WEP) at the US Navy's Maneuvering and Seakeeping (MASK) Basin at the Naval Surface Warfare Center in Carderock, Maryland. Measurements were made in the test area and upstream of the test area.

Applications of Fractal Analytical Techniques in the Estimation of Operational Scale

NASA Technical Reports Server (NTRS)

Emerson, Charles W.; Quattrochi, Dale A.

2000-01-01

The observational scale and the resolution of remotely sensed imagery are essential considerations in the interpretation process. Many atmospheric, hydrologic, and other natural and human-influenced spatial phenomena are inherently scale dependent and are governed by different physical processes at different spatial domains. This spatial and operational heterogeneity constrains the ability to compare interpretations of phenomena and processes observed in higher spatial resolution imagery to similar interpretations obtained from lower resolution imagery. This is a particularly acute problem, since longterm global change investigations will require high spatial resolution Earth Observing System (EOS), Landsat 7, or commercial satellite data to be combined with lower resolution imagery from older sensors such as Landsat TM and MSS. Fractal analysis is a useful technique for identifying the effects of scale changes on remotely sensed imagery. The fractal dimension of an image is a non-integer value between two and three which indicates the degree of complexity in the texture and shapes depicted in the image. A true fractal surface exhibits self-similarity, a property of curves or surfaces where each part is indistinguishable from the whole, or where the form of the curve or surface is invariant with respect to scale. Theoretically, if the digital numbers of a remotely sensed image resemble an ideal fractal surface, then due to the self-similarity property, the fractal dimension of the image will not vary with scale and resolution, and the slope of the fractal dimension-resolution relationship would be zero. Most geographical phenomena, however, are not self-similar at all scales, but they can be modeled by a stochastic fractal in which the scaling properties of the image exhibit patterns that can be described by statistics such as area-perimeter ratios and autocovariances. Stochastic fractal sets relax the self-similarity assumption and measure many scales and resolutions to represent the varying form of a phenomenon as the pixel size is increased in a convolution process. We have observed that for images of homogeneous land covers, the fractal dimension varies linearly with changes in resolution or pixel size over the range of past, current, and planned space-borne sensors. This relationship differs significantly in images of agricultural, urban, and forest land covers, with urban areas retaining the same level of complexity, forested areas growing smoother, and agricultural areas growing more complex as small pixels are aggregated into larger, mixed pixels. Images of scenes having a mixture of land covers have fractal dimensions that exhibit a non-linear, complex relationship to pixel size. Measuring the fractal dimension of a difference image derived from two images of the same area obtained on different dates showed that the fractal dimension increased steadily, then exhibited a sharp decrease at increasing levels of pixel aggregation. This breakpoint of the fractal dimension/resolution plot is related to the spatial domain or operational scale of the phenomenon exhibiting the predominant visible difference between the two images (in this case, mountain snow cover). The degree to which an image departs from a theoretical ideal fractal surface provides clues as to how much information is altered or lost in the processes of rescaling and rectification. The measured fractal dimension of complex, composite land covers such as urban areas also provides a useful textural index that can assist image classification of complex scenes.

Bench-scale synthesis of nanoscale materials

NASA Technical Reports Server (NTRS)

Buehler, M. F.; Darab, J. G.; Matson, D. W.; Linehan, J. C.

1994-01-01

A novel flow-through hydrothermal method used to synthesize nanoscale powders is introduced by Pacific Northwest Laboratory. The process, Rapid Thermal Decomposition of precursors in Solution (RTDS), uniquely combines high-pressure and high-temperature conditions to rapidly form nanoscale particles. The RTDS process was initially demonstrated on a laboratory scale and was subsequently scaled up to accommodate production rates attractive to industry. The process is able to produce a wide variety of metal oxides and oxyhydroxides. The powders are characterized by scanning and transmission electron microscopic methods, surface-area measurements, and x-ray diffraction. Typical crystallite sizes are less than 20 nanometers, with BET surface areas ranging from 100 to 400 sq m/g. A description of the RTDS process is presented along with powder characterization results. In addition, data on the sintering of nanoscale ZrO2 produced by RTDS are included.

Hurricane Frances as Observed by NASA Spaceborne Atmospheric Infrared Sounder AIRS and SeaWinds Scatterometer

NASA Image and Video Library

2004-08-30

This image shows Hurricane Frances in August 2004 as captured by instruments onboard two different NASA satellites: the AIRS infrared instrument onboard Aqua, and the SeaWinds scatterometer onboard QuikSCAT. Both are JPL-managed instruments. AIRS data are used to create global three-dimensional maps of temperature, humidity and clouds, while scatterometers measure surface wind speed and direction over the ocean. The red vectors in the image show Frances' surface winds as measured by SeaWinds on QuikSCAT. The background colors show the temperature of clouds and surface as viewed in the infrared by AIRS, with cooler areas pushing to purple and warmer areas are pushing to red. The color scale on the right gives the temperatures in degrees Kelvin. (The top of the scale, 320 degrees Kelvin, corresponds to 117 degrees Fahrenheit, and the bottom, 180 degrees K is -135 degrees F.) The powerful circulation of this storm is evident from the combined data as well as the development of a clearly-defined central "eye." The infrared signal does not penetrate through clouds, so the light blue areas reveal the cold clouds tops associated with strong thunderstorms embedded within the storm. In cloud-free areas the infrared signal comes from Earth's surface, revealing warmer temperatures. http://photojournal.jpl.nasa.gov/catalog/PIA00435

Fabrication of multi-scale periodic surface structures on Ti-6Al-4V by direct laser writing and direct laser interference patterning for modified wettability applications

NASA Astrophysics Data System (ADS)

Huerta-Murillo, D.; Aguilar-Morales, A. I.; Alamri, S.; Cardoso, J. T.; Jagdheesh, R.; Lasagni, A. F.; Ocaña, J. L.

2017-11-01

In this work, hierarchical surface patterns fabricated on Ti-6Al-4V alloy combining two laser micro-machining techniques are presented. The used technologies are based on nanosecond Direct Laser Writing and picosecond Direct Laser Interference Patterning. Squared shape micro-cells with different hatch distances were produced by Direct Laser Writing with depths values in the micro-scale, forming a well-defined closed packet. Subsequently, cross-like periodic patterns were fabricated by means of Direct Laser Interference Patterning using a two-beam configuration, generating a dual-scale periodic surface structure in both micro- and nano-scale due to the formation of Laser-Induced Periodic Surface Structure after the picosecond process. As a result a triple hierarchical periodic surface structure was generated. The surface morphology of the irradiated area was characterized with scanning electron microscopy and confocal microscopy. Additionally, static contact angle measurements were made to analyze the wettability behavior of the structures, showing a hydrophobic behavior for the hierarchical structures.

Insights into the role of wettability in cathode catalyst layer of proton exchange membrane fuel cell; pore scale immiscible flow and transport processes

NASA Astrophysics Data System (ADS)

Fathi, H.; Raoof, A.; Mansouri, S. H.

2017-05-01

The production of liquid water in cathode catalyst layer, CCL, is a significant barrier to increase the efficiency of proton exchange membrane fuel cell. Here we present, for the first time, a direct three-dimensional pore-scale modelling to look at the complex immiscible two-phase flow in CCL. After production of the liquid water at the surface of CCL agglomerates due to the electrochemical reactions, water spatial distribution affects transport of oxygen through the CCL as well as the rate of reaction at the agglomerate surfaces. To explore the wettability effects, we apply hydrophilic and hydrophobic properties using different surface contact angles. Effective diffusivity is calculated under several water saturation levels. Results indicate larger diffusive transport values for hydrophilic domain compared to the hydrophobic media where the liquid water preferentially floods the larger pores. However, hydrophobic domain showed more available surface area and higher oxygen consumption rate at the reaction sites under various saturation levels, which is explained by the effect of wettability on pore-scale distribution of water. Hydrophobic domain, with a contact angle of 150, reveals efficient water removal where only 28% of the pore space stays saturated. This condition contributes to the enhanced available reaction surface area and oxygen diffusivity.

Oxidation behavior and area specific resistance of La, Cu and B alloyed Fe-22Cr ferritic steels for solid oxide fuel cell interconnects

NASA Astrophysics Data System (ADS)

Swaminathan, Srinivasan; Ko, Yoon Seok; Lee, Young-Su; Kim, Dong-Ik

2017-11-01

Two Fe-22 wt% Cr ferritic stainless steels containing varying concentrations of La (0.14 or 0.52 wt%), Cu (0.17 or 1.74 wt%) and B (48 or 109 ppm) are investigated with respect to oxidation behavior and high temperature area specific resistance (ASR) of the surface oxide scales. To determine the oxidation resistance of developed steels, continuous isothermal oxidation is carried out at 800 °C in air, for 2000 h, and their thermally grown oxide scale is characterized using dynamic SIMS, SEM/EDX, XRD and GI-XRD techniques. To assess their electrical performance, the ASR measurement by four-point probe method is conducted at 800 °C in air, for 400 h. In higher La content steel, the La-oxides at the scale/alloy interface promotes the oxygen transport which resulted in sub-surface oxidation of Mn, Cr, Ti and Al. Moreover, the inward growth of oxides contributes to increase of Fe-Cr alloy protrusions within the scale, which reduced the ASR. In contrast, sub-surface oxidation is reduced in high Cu-alloyed steel by segregated Cu at the scale/alloy interface. Thus, addition of Cu is effective to oxidation resistance and also to better electrical performance. However, no obvious impact of B on the scale sequence and/or ASR is observed.

Greater sage-grouse population trends across Wyoming

USGS Publications Warehouse

Edmunds, David; Aldridge, Cameron L.; O'Donnell, Michael; Monroe, Adrian

2018-01-01

The scale at which analyses are performed can have an effect on model results and often one scale does not accurately describe the ecological phenomena of interest (e.g., population trends) for wide-ranging species: yet, most ecological studies are performed at a single, arbitrary scale. To best determine local and regional trends for greater sage-grouse (Centrocercus urophasianus) in Wyoming, USA, we modeled density-independent and -dependent population growth across multiple spatial scales relevant to management and conservation (Core Areas [habitat encompassing approximately 83% of the sage-grouse population on ∼24% of surface area in Wyoming], local Working Groups [7 regional areas for which groups of local experts are tasked with implementing Wyoming's statewide sage-grouse conservation plan at the local level], Core Area status (Core Area vs. Non-Core Area) by Working Groups, and Core Areas by Working Groups). Our goal was to determine the influence of fine-scale population trends (Core Areas) on larger-scale populations (Working Group Areas). We modeled the natural log of change in population size ( peak M lek counts) by time to calculate the finite rate of population growth (λ) for each population of interest from 1993 to 2015. We found that in general when Core Area status (Core Area vs. Non-Core Area) was investigated by Working Group Area, the 2 populations trended similarly and agreed with the overall trend of the Working Group Area. However, at the finer scale where Core Areas were analyzed separately, Core Areas within the same Working Group Area often trended differently and a few large Core Areas could influence the overall Working Group Area trend and mask trends occurring in smaller Core Areas. Relatively close fine-scale populations of sage-grouse can trend differently, indicating that large-scale trends may not accurately depict what is occurring across the landscape (e.g., local effects of gas and oil fields may be masked by increasing larger populations). 

Stream Flow Prediction by Remote Sensing and Genetic Programming

NASA Technical Reports Server (NTRS)

Chang, Ni-Bin

2009-01-01

A genetic programming (GP)-based, nonlinear modeling structure relates soil moisture with synthetic-aperture-radar (SAR) images to present representative soil moisture estimates at the watershed scale. Surface soil moisture measurement is difficult to obtain over a large area due to a variety of soil permeability values and soil textures. Point measurements can be used on a small-scale area, but it is impossible to acquire such information effectively in large-scale watersheds. This model exhibits the capacity to assimilate SAR images and relevant geoenvironmental parameters to measure soil moisture.

Destructive behavior of iron oxide in projectile impact

NASA Astrophysics Data System (ADS)

Shang, Wang; Xiaochen, Wang; Quan, Yang; Zhongde, Shan

2017-12-01

The damage strain values of Q235-A surface oxide scale were obtained by scanning electron microscopy (SEM/EDS) and universal tensile testing machine. The finite element simulation was carried out to study the destruction effects of oxidation at different impact rates. The results show that the damage value of the oxide strain is 0.08%. With the increase of the projectile velocity, the damage area of the oxide scale is increased, and the damage area is composed of the direct destruction area and the indirect failure area. The indirect damage area is caused by the stress/strain to the surrounding expansion after the impact of the steel body.

Multifractal characterisation of a simulated surface flow: A case study with Multi-Hydro in Jouy-en-Josas, France

NASA Astrophysics Data System (ADS)

Gires, Auguste; Abbes, Jean-Baptiste; da Silva Rocha Paz, Igor; Tchiguirinskaia, Ioulia; Schertzer, Daniel

2018-03-01

In this paper we suggest to innovatively use scaling laws and more specifically Universal Multifractals (UM) to analyse simulated surface runoff and compare the retrieved scaling features with the rainfall ones. The methodology is tested on a 3 km2 semi-urbanised with a steep slope study area located in the Paris area along the Bièvre River. First Multi-Hydro, a fully distributed model is validated on this catchment for four rainfall events measured with the help of a C-band radar. The uncertainty associated with small scale unmeasured rainfall, i.e. occurring below the 1 km × 1 km × 5 min observation scale, is quantified with the help of stochastic downscaled rainfall fields. It is rather significant for simulated flow and more limited on overland water depth for these rainfall events. Overland depth is found to exhibit a scaling behaviour over small scales (10 m-80 m) which can be related to fractal features of the sewer network. No direct and obvious dependency between the overland depth multifractal features (quality of the scaling and UM parameters) and the rainfall ones was found.

Downscaling Land Surface Temperature in Complex Regions by Using Multiple Scale Factors with Adaptive Thresholds

PubMed Central

Yang, Yingbao; Li, Xiaolong; Pan, Xin; Zhang, Yong; Cao, Chen

2017-01-01

Many downscaling algorithms have been proposed to address the issue of coarse-resolution land surface temperature (LST) derived from available satellite-borne sensors. However, few studies have focused on improving LST downscaling in urban areas with several mixed surface types. In this study, LST was downscaled by a multiple linear regression model between LST and multiple scale factors in mixed areas with three or four surface types. The correlation coefficients (CCs) between LST and the scale factors were used to assess the importance of the scale factors within a moving window. CC thresholds determined which factors participated in the fitting of the regression equation. The proposed downscaling approach, which involves an adaptive selection of the scale factors, was evaluated using the LST derived from four Landsat 8 thermal imageries of Nanjing City in different seasons. Results of the visual and quantitative analyses show that the proposed approach achieves relatively satisfactory downscaling results on 11 August, with coefficient of determination and root-mean-square error of 0.87 and 1.13 °C, respectively. Relative to other approaches, our approach shows the similar accuracy and the availability in all seasons. The best (worst) availability occurred in the region of vegetation (water). Thus, the approach is an efficient and reliable LST downscaling method. Future tasks include reliable LST downscaling in challenging regions and the application of our model in middle and low spatial resolutions. PMID:28368301

Surface Mining and Reclamation Effects on Flood Response of Watersheds in the Central Appalachian Plateau Region

NASA Technical Reports Server (NTRS)

Ferrari, J. R.; Lookingbill, T. R.; McCormick, B.; Townsend, P. A.; Eshleman, K. N.

2009-01-01

Surface mining of coal and subsequent reclamation represent the dominant land use change in the central Appalachian Plateau (CAP) region of the United States. Hydrologic impacts of surface mining have been studied at the plot scale, but effects at broader scales have not been explored adequately. Broad-scale classification of reclaimed sites is difficult because standing vegetation makes them nearly indistinguishable from alternate land uses. We used a land cover data set that accurately maps surface mines for a 187-km2 watershed within the CAP. These land cover data, as well as plot-level data from within the watershed, are used with HSPF (Hydrologic Simulation Program-Fortran) to estimate changes in flood response as a function of increased mining. Results show that the rate at which flood magnitude increases due to increased mining is linear, with greater rates observed for less frequent return intervals. These findings indicate that mine reclamation leaves the landscape in a condition more similar to urban areas rather than does simple deforestation, and call into question the effectiveness of reclamation in terms of returning mined areas to the hydrological state that existed before mining.

Spatial Correlations of Anomaly Time Series of AIRS Version-6 Land Surface Skin Temperatures with the Nino-4 Index

NASA Technical Reports Server (NTRS)

Susskind, Joel; Lee, Jae N.; Iredell, Lena

2013-01-01

The AIRS Science Team Version-6 data set is a valuable resource for meteorological studies. Quality Controlled earth's surface skin temperatures are produced on a 45 km x 45 km spatial scale under most cloud cover conditions. The same retrieval algorithm is used for all surface types under all conditions. This study used eleven years of AIRS monthly mean surface skin temperature and cloud cover products to show that land surface skin temperatures have decreased significantly in some areas and increased significantly in other areas over the period September 2002 through August 2013. These changes occurred primarily at 1:30 PM but not at 1:30 AM. Cooling land areas contained corresponding increases in cloud cover over this time period, with the reverse being true for warming land areas. The cloud cover anomaly patterns for a given month are affected significantly by El Nino/La Nina activity, and anomalies in cloud cover are a driving force behind anomalies in land surface skin temperature.

Exploring the Influence of Impervious Surface Density and Shape on Urban Heat Islands in the Northeast USA Using MODIS and Landsat

NASA Technical Reports Server (NTRS)

Zhang, Ping; Imhoff, Marc L.; Bounoua, Lahouri; Wolfe, Robert E.

2011-01-01

Impervious surface area (ISA) from the National Land Cover Database (NLCD) 2001 and land surface temperature (LST) from MODIS averaged over three annual cycles (2003-2005) are used in a spatial analysis to assess the urban heat island (UHI) signature and its relationship to settlement size and shape, development intensity distribution, and land cover composition for 42 urban settlements embedded in forest biomes in the Northeastern United States. Development intensity zones, based on percent ISA, are defined for each urban area emanating outward from the urban core to nearby rural areas and are used to stratify land surface temperature. The stratification is further constrained by biome type and elevation to insure objective intercomparisons between urban zones within an urban settlement and between settlements. Stratification based on ISA allows the definition of hierarchically ordered urban zones that are consistent across urban settlements and scales. In addition to the surrounding ecological context, we find that the settlement size and shape as well as the development intensity distribution significantly influence the amplitude of summer daytime UHI. Within the Northeastern US temperate broadleaf mixed forest, UHI magnitude is positively related to the logarithm of the urban area size. Our study indicates that for similar urban area sizes, the development intensity distribution is one of the major drivers of UHI. In addition to urban area size and development intensity distribution, this analysis shows that both the shape of the urban area and the land cover composition in the surrounding rural area play an important role in modulating the UHI magnitude in different urban settlements. Our results indicate that remotely sensed urban area size and shape as well as the development intensity distribution influence UHI amplitude across regional scales.

Statistical scaling of pore-scale Lagrangian velocities in natural porous media.

PubMed

Siena, M; Guadagnini, A; Riva, M; Bijeljic, B; Pereira Nunes, J P; Blunt, M J

2014-08-01

We investigate the scaling behavior of sample statistics of pore-scale Lagrangian velocities in two different rock samples, Bentheimer sandstone and Estaillades limestone. The samples are imaged using x-ray computer tomography with micron-scale resolution. The scaling analysis relies on the study of the way qth-order sample structure functions (statistical moments of order q of absolute increments) of Lagrangian velocities depend on separation distances, or lags, traveled along the mean flow direction. In the sandstone block, sample structure functions of all orders exhibit a power-law scaling within a clearly identifiable intermediate range of lags. Sample structure functions associated with the limestone block display two diverse power-law regimes, which we infer to be related to two overlapping spatially correlated structures. In both rocks and for all orders q, we observe linear relationships between logarithmic structure functions of successive orders at all lags (a phenomenon that is typically known as extended power scaling, or extended self-similarity). The scaling behavior of Lagrangian velocities is compared with the one exhibited by porosity and specific surface area, which constitute two key pore-scale geometric observables. The statistical scaling of the local velocity field reflects the behavior of these geometric observables, with the occurrence of power-law-scaling regimes within the same range of lags for sample structure functions of Lagrangian velocity, porosity, and specific surface area.

Towards Large-area Field-scale Operational Evapotranspiration for Water Use Mapping

NASA Astrophysics Data System (ADS)

Senay, G. B.; Friedrichs, M.; Morton, C.; Huntington, J. L.; Verdin, J.

2017-12-01

Field-scale evapotranspiration (ET) estimates are needed for improving surface and groundwater use and water budget studies. Ideally, field-scale ET estimates would be at regional to national levels and cover long time periods. As a result of large data storage and computational requirements associated with processing field-scale satellite imagery such as Landsat, numerous challenges remain to develop operational ET estimates over large areas for detailed water use and availability studies. However, the combination of new science, data availability, and cloud computing technology is enabling unprecedented capabilities for ET mapping. To demonstrate this capability, we used Google's Earth Engine cloud computing platform to create nationwide annual ET estimates with 30-meter resolution Landsat ( 16,000 images) and gridded weather data using the Operational Simplified Surface Energy Balance (SSEBop) model in support of the National Water Census, a USGS research program designed to build decision support capacity for water management agencies and other natural resource managers. By leveraging Google's Earth Engine Application Programming Interface (API) and developing software in a collaborative, open-platform environment, we rapidly advance from research towards applications for large-area field-scale ET mapping. Cloud computing of the Landsat image archive combined with other satellite, climate, and weather data, is creating never imagined opportunities for assessing ET model behavior and uncertainty, and ultimately providing the ability for more robust operational monitoring and assessment of water use at field-scales.

Assessing implicit models for nonpolar mean solvation forces: The importance of dispersion and volume terms

PubMed Central

Wagoner, Jason A.; Baker, Nathan A.

2006-01-01

Continuum solvation models provide appealing alternatives to explicit solvent methods because of their ability to reproduce solvation effects while alleviating the need for expensive sampling. Our previous work has demonstrated that Poisson-Boltzmann methods are capable of faithfully reproducing polar explicit solvent forces for dilute protein systems; however, the popular solvent-accessible surface area model was shown to be incapable of accurately describing nonpolar solvation forces at atomic-length scales. Therefore, alternate continuum methods are needed to reproduce nonpolar interactions at the atomic scale. In the present work, we address this issue by supplementing the solvent-accessible surface area model with additional volume and dispersion integral terms suggested by scaled particle models and Weeks–Chandler–Andersen theory, respectively. This more complete nonpolar implicit solvent model shows very good agreement with explicit solvent results and suggests that, although often overlooked, the inclusion of appropriate dispersion and volume terms are essential for an accurate implicit solvent description of atomic-scale nonpolar forces. PMID:16709675

A geometrically controlled rigidity transition in a model for confluent 3D tissues

NASA Astrophysics Data System (ADS)

Merkel, Matthias; Manning, M. Lisa

2018-02-01

The origin of rigidity in disordered materials is an outstanding open problem in statistical physics. Previously, a class of 2D cellular models has been shown to undergo a rigidity transition controlled by a mechanical parameter that specifies cell shapes. Here, we generalize this model to 3D and find a rigidity transition that is similarly controlled by the preferred surface area S 0: the model is solid-like below a dimensionless surface area of {s}0\\equiv {S}0/{\\bar{V}}2/3≈ 5.413 with \\bar{V} being the average cell volume, and fluid-like above this value. We demonstrate that, unlike jamming in soft spheres, residual stresses are necessary to create rigidity. These stresses occur precisely when cells are unable to obtain their desired geometry, and we conjecture that there is a well-defined minimal surface area possible for disordered cellular structures. We show that the behavior of this minimal surface induces a linear scaling of the shear modulus with the control parameter at the transition point, which is different from the scaling observed in particulate matter. The existence of such a minimal surface may be relevant for biological tissues and foams, and helps explain why cell shapes are a good structural order parameter for rigidity transitions in biological tissues.

Modelling landscape evolution at the flume scale

NASA Astrophysics Data System (ADS)

Cheraghi, Mohsen; Rinaldo, Andrea; Sander, Graham C.; Barry, D. Andrew

2017-04-01

The ability of a large-scale Landscape Evolution Model (LEM) to simulate the soil surface morphological evolution as observed in a laboratory flume (1-m × 2-m surface area) was investigated. The soil surface was initially smooth, and was subjected to heterogeneous rainfall in an experiment designed to avoid rill formation. Low-cohesive fine sand was placed in the flume while the slope and relief height were 5 % and 20 cm, respectively. Non-uniform rainfall with an average intensity of 85 mm h-1 and a standard deviation of 26 % was applied to the sediment surface for 16 h. We hypothesized that the complex overland water flow can be represented by a drainage discharge network, which was calculated via the micro-morphology and the rainfall distribution. Measurements included high resolution Digital Elevation Models that were captured at intervals during the experiment. The calibrated LEM captured the migration of the main flow path from the low precipitation area into the high precipitation area. Furthermore, both model and experiment showed a steep transition zone in soil elevation that moved upstream during the experiment. We conclude that the LEM is applicable under non-uniform rainfall and in the absence of surface incisions, thereby extending its applicability beyond that shown in previous applications. Keywords: Numerical simulation, Flume experiment, Particle Swarm Optimization, Sediment transport, River network evolution model.

Thermal Analysis of Unusual Local-scale Features on the Surface of Vesta

NASA Technical Reports Server (NTRS)

Tosi, F.; Capria, M. T.; DeSanctis, M. C.; Capaccioni, F.; Palomba, E.; Zambon, F.; Ammannito, E.; Blewett, D. T.; Combe, J.-Ph.; Denevi, B. W.;

Scaling and biomechanics of surface attachment in climbing animals

PubMed Central

Labonte, David; Federle, Walter

2015-01-01

Attachment devices are essential adaptations for climbing animals and valuable models for synthetic adhesives. A major unresolved question for both natural and bioinspired attachment systems is how attachment performance depends on size. Here, we discuss how contact geometry and mode of detachment influence the scaling of attachment forces for claws and adhesive pads, and how allometric data on biological systems can yield insights into their mechanism of attachment. Larger animals are expected to attach less well to surfaces, due to their smaller surface-to-volume ratio, and because it becomes increasingly difficult to distribute load uniformly across large contact areas. In order to compensate for this decrease of weight-specific adhesion, large animals could evolve overproportionally large pads, or adaptations that increase attachment efficiency (adhesion or friction per unit contact area). Available data suggest that attachment pad area scales close to isometry within clades, but pad efficiency in some animals increases with size so that attachment performance is approximately size-independent. The mechanisms underlying this biologically important variation in pad efficiency are still unclear. We suggest that switching between stress concentration (easy detachment) and uniform load distribution (strong attachment) via shear forces is one of the key mechanisms enabling the dynamic control of adhesion during locomotion. PMID:25533088

Functionalised Silk Fibres

DTIC Science & Technology

2012-07-30

rubber moulds (14 x 5 x 6 mm; RL060, ProSciTech, QLD), frozen at -20ºC overnight, and placed in a freeze - dryer (FD355DMP, FTS Systems) for 24 hours...surface area, low volume materials: electrospun fibres and freeze -dried sponges (Figure 9). Each new material type is described in detail below...surface area materials generated from recombinant honeybee silk proteins. (A) Electrospun fibres, scale bar is 200 nm. (B) Freeze dried sponges

Scaling up from field to region for wind erosion prediction using a field-scale wind erosion model and GIS

USGS Publications Warehouse

Zobeck, T.M.; Parker, N.C.; Haskell, S.; Guoding, K.

2000-01-01

Factors that affect wind erosion such as surface vegetative and other cover, soil properties and surface roughness usually change spatially and temporally at the field-scale to produce important field-scale variations in wind erosion. Accurate estimation of wind erosion when scaling up from fields to regions, while maintaining meaningful field-scale process details, remains a challenge. The objectives of this study were to evaluate the feasibility of using a field-scale wind erosion model with a geographic information system (GIS) to scale up to regional levels and to quantify the differences in wind erosion estimates produced by different scales of soil mapping used as a data layer in the model. A GIS was used in combination with the revised wind erosion equation (RWEQ), a field-scale wind erosion model, to estimate wind erosion for two 50 km2 areas. Landsat Thematic Mapper satellite imagery from 1993 with 30 m resolution was used as a base map. The GIS database layers included land use, soils, and other features such as roads. The major land use was agricultural fields. Data on 1993 crop management for selected fields of each crop type were collected from local government agency offices and used to 'train' the computer to classify land areas by crop and type of irrigation (agroecosystem) using commercially available software. The land area of the agricultural land uses was overestimated by 6.5% in one region (Lubbock County, TX, USA) and underestimated by about 21% in an adjacent region (Terry County, TX, USA). The total estimated wind erosion potential for Terry County was about four times that estimated for adjacent Lubbock County. The difference in potential erosion among the counties was attributed to regional differences in surface soil texture. In a comparison of different soil map scales in Terry County, the generalised soil map had over 20% more of the land area and over 15% greater erosion potential in loamy sand soils than did the detailed soil map. As a result, the wind erosion potential determined using the generalised soil map Was about 26% greater than the erosion potential estimated by using the detailed soil map in Terry County. This study demonstrates the feasibility of scaling up from fields to regions to estimate wind erosion potential by coupling a field-scale wind erosion model with GIS and identifies possible sources of error with this approach.

The potential for translocation of marine species via small-scale disruptions to antifouling surfaces.

PubMed

Piola, Richard F; Johnston, Emma L

2008-01-01

Vessel hull fouling is a major vector for the translocation of nonindigenous species (NIS). Antifouling (AF) paints are the primary method for preventing the establishment and translocation of fouling species. However, factors such as paint age, condition and method of application can all reduce the effectiveness of these coatings. Areas of hull that escape AF treatment (through limited application or damage) constitute key areas that may be expected to receive high levels of fouling. The investigation focused on whether small-scale (mm(2) to cm(2)) areas of unprotected surface or experimental 'scrapes' provided sufficient area for the formation of fouling assemblages within otherwise undamaged AF surfaces. Recruitment of fouling taxa such as algae, spirorbids and hydroids was recorded on scrapes as narrow as 0.5 cm wide. The abundance and species richness of fouling assemblages developing on scrapes > or =1 cm often equalled or surpassed levels observed in reference assemblages totally unprotected by AF coatings. Experiments were conducted at three sites within the highly protected and isolated marine park surrounding Lady Elliott Island at the southernmost tip of the Great Barrier Reef, Australia. Several NIS were recorded on scrapes of AF coated surfaces at this location, with 1-cm scrapes showing the greatest species richness and abundance of NIS relative to all other treatments (including controls) at two of the three sites investigated. Slight disruptions to newly antifouled surfaces may be all that is necessary for the establishment of fouling organisms and the translocation of a wide range of invasive taxa to otherwise highly protected marine areas.

Temporal changes in surface roughness around 88°S from repeat high-resolution Airborne Topographic Mapper laser altimetry

NASA Astrophysics Data System (ADS)

Studinger, M.; Brunt, K. M.; Medley, B.; Casey, K.; Neumann, T.

2017-12-01

The southern convergence of all ICESat-2 and CryoSat-2 tracks at 88°S is in a region of relatively low accumulation and surface slope making it ideal for satellite altimetry calibration and validation. In order to evaluate the stability and surface characteristics of the area we have analyzed repeat airborne laser altimetry measurements acquired around 88°S during 2014 and 2016 by NASA's Airborne Topographic Mapper (ATM) as part of Operation IceBridge. ATM is a conical scanner that operates at a wavelength of 532 nm, with a footprint of 1 meter and a 250-m-wide swath on the ground. The ATM Level 2 ICESSN data product includes slope and roughness estimates in 80 m × 80 m platelets across the swath. The mean surface roughness around 88°S for the 2014 data is 9.4 ± 2.0 cm, with the repeat flights in 2016 showing 8.6 ± 2.8 cm. The 2014 data reveals several areas where surface roughness doubles over very short spatial scales of only a few hundred meters. These features are several tens of km wide and appear to be oriented parallel to the main sastrugi direction visible in ATM spot elevation data and Digital Mapping System (DMS) visual imagery collected simultaneously. The rougher surface features are also present in the CReSIS snow radar data collected at the same time. These areas of increased surface roughness disappear in 2016 or seem to be significantly reduced in amplitude with the sharpness of the edges significantly reduced. The combination of simultaneous altimetry, snow radar and visual imagery on a regional scale provides a unique data set to study small scale deposition and erosional processes and their temporal variability. Our long-term goal is to quantify the spatial variability in snow accumulation rates south of 86°S in support of past, current and future altimetry measurements and surface mass balance model evaluation.

Monitoring and assessment of soil erosion at micro-scale and macro-scale in forests affected by fire damage in northern Iran.

PubMed

Akbarzadeh, Ali; Ghorbani-Dashtaki, Shoja; Naderi-Khorasgani, Mehdi; Kerry, Ruth; Taghizadeh-Mehrjardi, Ruhollah

2016-12-01

Understanding the occurrence of erosion processes at large scales is very difficult without studying them at small scales. In this study, soil erosion parameters were investigated at micro-scale and macro-scale in forests in northern Iran. Surface erosion and some vegetation attributes were measured at the watershed scale in 30 parcels of land which were separated into 15 fire-affected (burned) forests and 15 original (unburned) forests adjacent to the burned sites. The soil erodibility factor and splash erosion were also determined at the micro-plot scale within each burned and unburned site. Furthermore, soil sampling and infiltration studies were carried out at 80 other sites, as well as the 30 burned and unburned sites, (a total of 110 points) to create a map of the soil erodibility factor at the regional scale. Maps of topography, rainfall, and cover-management were also determined for the study area. The maps of erosion risk and erosion risk potential were finally prepared for the study area using the Revised Universal Soil Loss Equation (RUSLE) procedure. Results indicated that destruction of the protective cover of forested areas by fire had significant effects on splash erosion and the soil erodibility factor at the micro-plot scale and also on surface erosion, erosion risk, and erosion risk potential at the watershed scale. Moreover, the results showed that correlation coefficients between different variables at the micro-plot and watershed scales were positive and significant. Finally, assessment and monitoring of the erosion maps at the regional scale showed that the central and western parts of the study area were more susceptible to erosion compared with the western regions due to more intense crop-management, greater soil erodibility, and more rainfall. The relationships between erosion parameters and the most important vegetation attributes were also used to provide models with equations that were specific to the study region. The results of this paper can be useful for better understanding erosion processes at the micro-scale and macro-scale in any region having similar vegetation attributes to the forests of northern Iran.

Abiotic controls of emergent macrophyte density in a bedrock channel - The Cahaba River, AL (USA)

NASA Astrophysics Data System (ADS)

Vaughn, Ryan S.; Davis, Lisa

2015-10-01

Research examining bedrock channels is growing. Despite this, biotic-abiotic interactions remain a topic mostly addressed in alluvial systems. This research identified hydrogeomorphic factors operating at the patch-scale (100-102 m) in bedrock shoals of the Cahaba River (AL) that help determine the distribution of the emergent aquatic macrophyte, Justicia americana. Macrophyte patch density (number of stems/m2) and percent bedrock void surface area (rock surface area/m2 occupied by joints, fractures, and potholes) were measured (n = 24 within two bedrock shoals) using stem counts and underwater photography, respectively. One-dimensional hydrologic modeling (HEC-RAS 4.1.0) was completed for a section within a shoal to examine velocity and channel depth as controlling variables for macrophyte patch density. Results from binary logistic regression analysis identified depth and velocity as good predictors of the presence or absence of Justicia americana within shoal structures (depth p = 0.001, velocity p = 0.007), which is a similar finding to previous research conducted in alluvial systems. Correlation analysis between bedrock surface void area and stem density demonstrated a statistically significant positive correlation (r = 0.665, p = 0.01), elucidating a link between abiotic-biotic processes that may well be unique to bedrock channels. These results suggest that the amount of void space present in bedrock surfaces, in addition to localized depth and velocity, helps control macrophyte patch density in bedrock shoal complexes. The utility of geomorphology in explaining patch-scale habitat heterogeneity in this study highlights geomorphology's potential to help understand macrophyte habitat heterogeneity at the reach scale, while also demonstrating its promise for mapping and understanding habitat heterogeneity at the system scale.

Pore-scale spectral induced polarization (SIP) signaturesassociated with FeS biomineral transformations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slater, Lee; Ntarlagiannis, Dimitrios; Personna, Yves R.

2007-10-01

The authors measured Spectral Induced Polarization (SIP) signatures in sand columns during (1) FeS biomineralization produced by sulfate reducing bacteria (D. vulgaris) under anaerboci conditions, and (2) subsequent biomineral dissolution upon return to an aerobic state. The low-frequency (0.1-10 Hz peak) relaxations produced during biomineralization can be modeled with a Cole-Cole formulation, from which the evolution of the polarization magnitude and relaxation length scale can be estimated. They find that the modeled time constant is consistent with the polarizable elements being biomineral encrused pores. Evolution of the model parameters is consistent with FeS surface area increases and pore-size reduction duringmore » biomineral growth, and subsequent biomineral dissolution (FeS surface area decreases and pore expansion) upon return to the aerobic state. They conclude that SIP signatures are diagnostic of pore-scale geometrical changes associated with FeS biomineralization by sulfate reducing bacteria.« less

Measuring floodplain spatial patterns using continuous surface metrics at multiple scales

USGS Publications Warehouse

Scown, Murray W.; Thoms, Martin C.; DeJager, Nathan R.

2015-01-01

Interactions between fluvial processes and floodplain ecosystems occur upon a floodplain surface that is often physically complex. Spatial patterns in floodplain topography have only recently been quantified over multiple scales, and discrepancies exist in how floodplain surfaces are perceived to be spatially organised. We measured spatial patterns in floodplain topography for pool 9 of the Upper Mississippi River, USA, using moving window analyses of eight surface metrics applied to a 1 × 1 m2 DEM over multiple scales. The metrics used were Range, SD, Skewness, Kurtosis, CV, SDCURV,Rugosity, and Vol:Area, and window sizes ranged from 10 to 1000 m in radius. Surface metric values were highly variable across the floodplain and revealed a high degree of spatial organisation in floodplain topography. Moran's I correlograms fit to the landscape of each metric at each window size revealed that patchiness existed at nearly all window sizes, but the strength and scale of patchiness changed within window size, suggesting that multiple scales of patchiness and patch structure exist in the topography of this floodplain. Scale thresholds in the spatial patterns were observed, particularly between the 50 and 100 m window sizes for all surface metrics and between the 500 and 750 m window sizes for most metrics. These threshold scales are ~ 15–20% and 150% of the main channel width (1–2% and 10–15% of the floodplain width), respectively. These thresholds may be related to structuring processes operating across distinct scale ranges. By coupling surface metrics, multi-scale analyses, and correlograms, quantifying floodplain topographic complexity is possible in ways that should assist in clarifying how floodplain ecosystems are structured.

High Surface Area Dendrite Nanoelectrodes for Electrochemistry

NASA Astrophysics Data System (ADS)

Nesbitt, Nathan; Glover, Jennifer; Goyal, Saurabh; Simidjiysky, Svetoslav; Naughton, Michael

2014-03-01

Solution-based electrodeposition of metal using a low ion concentration, surface passivation agents, and/or electrochemical crystal conditioning has allowed for the formation of high surface area metal electrodes, useful for Raman spectroscopy and electrochemical sensors. Additionally, high frequency electrical oscillations have been used to electrically connect co-planar electrodes, a process called directed electrochemical nanowire assembly (DENA). These approaches aim to control the crystal face that metal atoms in solution will nucleate onto, thus causing anisotropic growth of metal crystals. However, DENA has not been used to create high surface area electrodes, and no study has been conducted on the effect of micron-scale surface topography on the initial nucleation of metal crystals on the electrode surface. When DENA is used to create a high surface area electrode, such a texture has a strong impact on the subsequent topography of the three dimensional dendritic structures by limiting the areal density of crystals on the electrode surface. Such structures both demonstrate unique physics concerning the nucleation of metal dendrites, and offer a unique and highly facile fabrication method of high surface area electrodes, useful for chemical and biological sensing. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. (DGE-1258923).

Does lake size matter? Combining morphology and process modeling to examine the contribution of lake classes to population-scale processes

USGS Publications Warehouse

Winslow, Luke A.; Read, Jordan S.; Hanson, Paul C.; Stanley, Emily H.

2014-01-01

With lake abundances in the thousands to millions, creating an intuitive understanding of the distribution of morphology and processes in lakes is challenging. To improve researchers’ understanding of large-scale lake processes, we developed a parsimonious mathematical model based on the Pareto distribution to describe the distribution of lake morphology (area, perimeter and volume). While debate continues over which mathematical representation best fits any one distribution of lake morphometric characteristics, we recognize the need for a simple, flexible model to advance understanding of how the interaction between morphometry and function dictates scaling across large populations of lakes. These models make clear the relative contribution of lakes to the total amount of lake surface area, volume, and perimeter. They also highlight the critical thresholds at which total perimeter, area and volume would be evenly distributed across lake size-classes have Pareto slopes of 0.63, 1 and 1.12, respectively. These models of morphology can be used in combination with models of process to create overarching “lake population” level models of process. To illustrate this potential, we combine the model of surface area distribution with a model of carbon mass accumulation rate. We found that even if smaller lakes contribute relatively less to total surface area than larger lakes, the increasing carbon accumulation rate with decreasing lake size is strong enough to bias the distribution of carbon mass accumulation towards smaller lakes. This analytical framework provides a relatively simple approach to upscaling morphology and process that is easily generalizable to other ecosystem processes.

Minimizing the area required for time constants in integrated circuits

NASA Technical Reports Server (NTRS)

Lyons, J. C.

1972-01-01

When a medium- or large-scale integrated circuit is designed, efforts are usually made to avoid the use of resistor-capacitor time constant generators. The capacitor needed for this circuit usually takes up more surface area on the chip than several resistors and transistors. When the use of this network is unavoidable, the designer usually makes an effort to see that the choice of resistor and capacitor combinations is such that a minimum amount of surface area is consumed. The optimum ratio of resistance to capacitance that will result in this minimum area is equal to the ratio of resistance to capacitance which may be obtained from a unit of surface area for the particular process being used. The minimum area required is a function of the square root of the reciprocal of the products of the resistance and capacitance per unit area. This minimum occurs when the area required by the resistor is equal to the area required by the capacitor.

Startup of reactors for anoxic ammonium oxidation: experiences from the first full-scale anammox reactor in Rotterdam.

PubMed

van der Star, Wouter R L; Abma, Wiebe R; Blommers, Dennis; Mulder, Jan-Willem; Tokutomi, Takaaki; Strous, Marc; Picioreanu, Cristian; van Loosdrecht, Mark C M

2007-10-01

The first full-scale anammox reactor in the world was started in Rotterdam (NL). The reactor was scaled-up directly from laboratory-scale to full-scale and treats up to 750 kg-N/d. In the initial phase of the startup, anammox conversions could not be identified by traditional methods, but quantitative PCR proved to be a reliable indicator for growth of the anammox population, indicating an anammox doubling time of 10-12 days. The experience gained during this first startup in combination with the availability of seed sludge from this reactor, will lead to a faster startup of anammox reactors in the future. The anammox reactor type employed in Rotterdam was compared to other reactor types for the anammox process. Reactors with a high specific surface area like the granular sludge reactor employed in Rotterdam provide the highest volumetric loading rates. Mass transfer of nitrite into the biofilm is limiting the conversion of those reactor types that have a lower specific surface area. Now the first full-scale commercial anammox reactor is in operation, a consistent and descriptive nomenclature is suggested for reactors in which the anammox process is employed.

Characterization of nanoporous shales with gas sorption

NASA Astrophysics Data System (ADS)

Joewondo, N.; Prasad, M.

2017-12-01

The understanding of the fluid flow in porous media requires the knowledge of the pore system involved. Fluid flow in fine grained shales falls under different regime than transport regime in conventional reservoir due to the different average pore sizes in the two materials; the average pore diameter of conventional sandstones is on the micrometer scale, while of shales can be as small as several nanometers. Mercury intrusion porosimetry is normally used to characterize the pores of conventional reservoir, however with increasingly small pores, the injection pressure required to imbibe the pores becomes infinitely large due to surface tension. Characterization of pores can be expressed by a pore size distribution (PSD) plot, which reflects distribution of pore volume or surface area with respect to pore size. For the case of nanoporous materials, the surface area, which serves as the interface between the rock matrix and fluid, becomes increasingly large and important. Physisorption of gas has been extensively studied as a method of nanoporous solid characterization (particularly for the application of catalysis, metal organic frameworks, etc). The PSD is obtained by matching the experimental result to the calculated theoretical result (using Density Functional Theory (DFT), a quantum mechanics based modelling method for molecular scale interactions). We present the challenges and experimental result of Nitrogen and CO2 gas sorption on shales with various mineralogy and the interpreted PSD obtained by DFT method. Our result shows significant surface area contributed by the nanopores of shales, hence the importance of surface area measurements for the characterization of shales.

Utilization of Large Scale Surface Models for Detailed Visibility Analyses

NASA Astrophysics Data System (ADS)

Caha, J.; Kačmařík, M.

2017-11-01

This article demonstrates utilization of large scale surface models with small spatial resolution and high accuracy, acquired from Unmanned Aerial Vehicle scanning, for visibility analyses. The importance of large scale data for visibility analyses on the local scale, where the detail of the surface model is the most defining factor, is described. The focus is not only the classic Boolean visibility, that is usually determined within GIS, but also on so called extended viewsheds that aims to provide more information about visibility. The case study with examples of visibility analyses was performed on river Opava, near the Ostrava city (Czech Republic). The multiple Boolean viewshed analysis and global horizon viewshed were calculated to determine most prominent features and visibility barriers of the surface. Besides that, the extended viewshed showing angle difference above the local horizon, which describes angular height of the target area above the barrier, is shown. The case study proved that large scale models are appropriate data source for visibility analyses on local level. The discussion summarizes possible future applications and further development directions of visibility analyses.

Innovative potential of plasma technology

NASA Astrophysics Data System (ADS)

Budaev, V. P.

2017-11-01

The review summarizes recent experimental observations of materials exposed to extreme hot plasma loads in fusion devices and plasma facilities with high-temperature plasma. Plasma load on the material in such devices lead to the stochastic clustering and fractal growth of the surface on scales from tens of nanometers to hundreds of micrometers forming statistical self-similarity of the surface roughness with extremely high specific area. Statistical characteristics of hierarchical granularity and scale invariance of such materials surface qualitatively differ from the properties of the roughness of the ordinary Brownian surface which provides a potential of innovative plasma technologies for synthesis of new nanostructured materials with programmed roughness properties, for hypersonic technologies, for biotechnology and biomedical applications.

Spatial variability and landscape controls of near-surface permafrost within the Alaskan Yukon River Basin

USGS Publications Warehouse

Pastick, Neal J.; Jorgenson, M. Torre; Wylie, Bruce K.; Rose, Joshua R.; Rigge, Matthew; Walvoord, Michelle Ann

2014-01-01

The distribution of permafrost is important to understand because of permafrost's influence on high-latitude ecosystem structure and functions. Moreover, near-surface (defined here as within 1 m of the Earth's surface) permafrost is particularly susceptible to a warming climate and is generally poorly mapped at regional scales. Subsequently, our objectives were to (1) develop the first-known binary and probabilistic maps of near-surface permafrost distributions at a 30 m resolution in the Alaskan Yukon River Basin by employing decision tree models, field measurements, and remotely sensed and mapped biophysical data; (2) evaluate the relative contribution of 39 biophysical variables used in the models; and (3) assess the landscape-scale factors controlling spatial variations in permafrost extent. Areas estimated to be present and absent of near-surface permafrost occupy approximately 46% and 45% of the Alaskan Yukon River Basin, respectively; masked areas (e.g., water and developed) account for the remaining 9% of the landscape. Strong predictors of near-surface permafrost include climatic indices, land cover, topography, and Landsat 7 Enhanced Thematic Mapper Plus spectral information. Our quantitative modeling approach enabled us to generate regional near-surface permafrost maps and provide essential information for resource managers and modelers to better understand near-surface permafrost distribution and how it relates to environmental factors and conditions.

Proton exchange membrane and electrode surface areas as factors that affect power generation in microbial fuel cells.

PubMed

Oh, Sang-Eun; Logan, Bruce E

2006-03-01

Power generation in microbial fuel cells (MFCs) is a function of the surface areas of the proton exchange membrane (PEM) and the cathode relative to that of the anode. To demonstrate this, the sizes of the anode and cathode were varied in two-chambered MFCs having PEMs with three different surface areas (A (PEM)=3.5, 6.2, or 30.6 cm(2)). For a fixed anode and cathode surface area (A (An)=A (Cat)=22.5 cm(2)), the power density normalized to the anode surface area increased with the PEM size in the order 45 mW/m(2) (A (PEM)=3.5 cm(2)), 68 mW/m(2) (A (PEM)=6.2 cm(2)), and 190 mW/m(2) (A (PEM)=30.6 cm(2)). PEM surface area was shown to limit power output when the surface area of the PEM was smaller than that of the electrodes due to an increase in internal resistance. When the relative cross sections of the PEM, anode, and cathode were scaled according to 2A (Cat)=A(PEM)=2A (An), the maximum power densities of the three different MFCs, based on the surface area of the PEM (A (PEM)=3.5, 6.2, or 30.6 cm(2)), were the same (168+/-4.53 mW/m(2)). Increasing the ionic strength and using ferricyanide at the cathode also increased power output.

Changing spatial patterns of evapotranspiration and deep drainage in response to the interactions among impervious surface arrangement, soil characteristics, and weather on a residential parcel.

NASA Astrophysics Data System (ADS)

Voter, C. B.; Steven, L. I.

2015-12-01

The introduction impervious surfaces in urban areas is a key driver of hydrologic change. It is now well understood that the amount of "effective" impervious area directly connected to the storm sewer network is a better indicator of hydrologic behavior than the total amount of impervious area. Most studies in urban hydrology have focused on the relationship between impervious connectivity and stormwater runoff or other surface water flows, with the result that the effect on subsurface flow is not as well understood. In the field, we observe differences in soil moisture availability that are dependent on proximity to impervious features and significant from a root water uptake perspective, which indicates that parcel-scale subsurface and plant water fluxes may also be sensitive to fine-scaled heterogeneity in impervious surface arrangement and connectivity. We use ParFlow with CLM, a watershed model with fully integrated variably-saturated subsurface flow, overland flow, and land-surface processes, to explore the extent to which soil moisture, evapotranspiration, and deep drainage vary under various impervious surface arrangement and soil condition scenarios, as well as under a range of precipitation regimes. We investigate the effect of several impervious surface and soil characteristics, including general lot layout, downspout disconnect, and direction of driveway/sidewalk slope, and soil compaction. We show that that some impervious connectivity schemes transfer more water from impervious areas to pervious ones and promote localized recharge by developing well-defined, fast-moving wetting fronts that are able to penetrate the root zone. Enhanced infiltration is translated more directly to recharge in normal to wet years but partitioned more often to transpiration in dry years, leading to a nonlinear relationship among precipitation, runoff and recharge.

Assessing Regional Scale Fluxes of Mass, Momentum, and Energy with Small Environmental Research Aircraft

NASA Astrophysics Data System (ADS)

Zulueta, Rommel Callejo

Natural ecosystems are rarely structurally or functionally homogeneous. This is true for the complex coastal regions of Magdalena Bay, Baja California Sur, Mexico, and the Barrow Peninsula on the Arctic Coastal Plain of Alaska. The coastal region of Magdalena Bay is comprised of the Pacific coastal ocean, eutrophic lagoon, mangroves, and desert ecosystems all adjacent and within a few kilometers, while the Barrow Peninsula is a mosaic of small ponds, thaw lakes, different aged vegetated thaw-lake basins ( VDTLBs ) and interstitial tundra which have been dynamically formed by both short- and long-term processes. We used a combination of tower- and small environmental research aircraft (SERA)-based eddy covariance measurements to characterize the spatial and temporal patterns of CO2, latent, and sensible heat fluxes along with MODIS NDVI, and land surface information, to scale the SERA-based CO2 fluxes up to the regional scale. In the first part of this research, the spatial variability in ecosystem fluxes from the Pacific coastal ocean, eutrophic lagoon, mangroves, and desert areas of northern Magdalena Bay were studied. SERA-derived average midday CO2 fluxes from the desert showed a slight uptake of -1.32 mumol CO2 m-2 s-1, the coastal ocean also showed uptake of -3.48 mumol CO2 m-2 s -1, and the lagoon mangroves showed the highest uptake of -8.11 mumol CO2 m-2 s-1. Additional simultaneous measurements of NDVI allowed simple linear modeling of CO2 flux as a function of NDVI for the mangroves of the Magdalena Bay region. In the second part of this research, the spatial variability of ecosystem fluxes across the 1802 km2 Barrow Peninsula region was studied. During typical 2006 summer conditions, the midday hourly CO2 flux over the region was -2.04 x 105 kgCO2 hr-1. The CO2 fluxes among the interstitial tundra, Ancient and Old VDTLBs, as well as between the Medium and Young VDTLBs were not significantly different. Combined, the interstitial tundra and Old and Ancient VDTLBs, represent ˜67% of the Barrow Peninsula surface area, accounting for ˜59% of the regional flux signal. Though the Medium and Young VDTLBs represent ˜11% of the surface area, they account for a large portion, ˜35%, of the total regional flux. The remaining ˜22% of the surface area are lakes and contributed the remaining ˜6% of the total regional flux. Previous studies treated vegetated areas of the region as a single surface type with measurements from a few study sites; doing so could underestimate the regional flux by ˜22%. The San Diego State University Sky Arrow 650TCN Environmental Research Aircraft proved to be an effective tool in characterizing land-atmosphere fluxes of energy, CO2 and water across heterogeneous landscapes at the scale of 1 km, and was capable of discriminating fluxes from the various ecosystem and land surface types a few kilometers distant. Here, we demonstrate that SERA-based approaches have the ability to cover large spatial scales while measuring the turbulent fluxes across a number of surfaces and combined with ground- and satellite-based measurements provide a valuable tool for both scaling and validation of regional-scale fluxes.

On the theory relating changes in area-average and pan evaporation (Invited)

NASA Astrophysics Data System (ADS)

Shuttleworth, W.; Serrat-Capdevila, A.; Roderick, M. L.; Scott, R.

2009-12-01

Theory relating changes in area-average evaporation with changes in the evaporation from pans or open water is developed. Such changes can arise by Type (a) processes related to large-scale changes in atmospheric concentrations and circulation that modify surface evaporation rates in the same direction, and Type (b) processes related to coupling between the surface and atmospheric boundary layer (ABL) at the landscape scale that usually modify area-average evaporation and pan evaporation in different directions. The interrelationship between evaporation rates in response to Type (a) changes is derived. They have the same sign and broadly similar magnitude but the change in area-average evaporation is modified by surface resistance. As an alternative to assuming the complementary evaporation hypothesis, the results of previous modeling studies that investigated surface-atmosphere coupling are parameterized and used to develop a theoretical description of Type (b) coupling via vapor pressure deficit (VPD) in the ABL. The interrelationship between appropriately normalized pan and area-average evaporation rates is shown to vary with temperature and wind speed but, on average, the Type (b) changes are approximately equal and opposite. Long-term Australian pan evaporation data are analyzed to demonstrate the simultaneous presence of Type (a) and (b) processes, and observations from three field sites in southwestern USA show support for the theory describing Type (b) coupling via VPD. England's victory over Australia in 2009 Ashes cricket test match series will not be mentioned.

Superimposing various biophysical and social scales in a rapidly changing rural area (SW Niger)

NASA Astrophysics Data System (ADS)

Leduc, Christian; Massuel, Sylvain; Favreau, Guillaume; Cappelaere, Bernard; Leblanc, Marc; Bachir, Salifou; Ousmane, Boureïma

2014-05-01

In SW Niger, close to Niamey, a detailed hydrological survey has been developed for the last 20 years (international experiments HAPEX-SAHEL and later AMMA), investigating the distribution of water in atmosphere, surface, soil and aquifers. It covers an area of about 10 000 km2, with a series of imbricated scales of instrumentation, in time and space. This dense long term field observation led to many major scientific results. Among them, one of the most original and paradoxical is the continuous rise of the water table, even during the severe droughts of the 1970s and 1980s (about 3 m in the last 30 years). In spite of a large apparent homogeneity of the biophysical environment throughout the region, numerous heterogeneities exist at different scales, complicating the hydrological analysis. On the surface, the hydrological system was, ~6000 years ago, a structured drainage network leading to the Niger River. It was later broken into much smaller elements by aeolian dunes deposited during arid episodes and the study area now appears as a juxtaposition of hundreds of small endorheic catchments (most often 1 to 20 km2) where the surface runoff finally ends in temporary ponds. During most violent rainy events, erosion can be locally very severe and modify durably the size of the catchment and the local hydrology. Conversely, during smaller rainy events, surface runoff may never reach the ponds because it infiltrates in more permeable zones at mid-slope. The actual surface area of the catchment contributing to the surface runoff thus varies considerably with time. Because of their great number, only a few catchments are instrumented and extrapolation of measurements to ungauged catchments is an additional difficulty. Most of water temporarily stored in ponds infiltrates and recharges groundwater. The Continental Terminal (CT) aquifer system is made of three independent layers, of which the upper one (CT3) is only considered here. The CT aquifer systems is a transboundary aquifer that extends far beyond the study area, over about 150 000 km2. It is also heterogeneous. Like surface flows, but at a different scale, groundwater flows are marked by a strong endorheism. For example the Dantiandou closed piezometric depression extends over about approximately 5000 km2. These natural closed depressions are explained only by evapotranspiration uptake, weak in absolute terms (a few mm.a-1) but with a very high impact on hydrodynamics because of poor permeability and porosity. Both density of observations and hydraulic continuity of the CT3 aquifer give a fine idea of groundwater changes in the whole area. Human activities, continuously adapting in this poor rural area, add another complexity to the hydrological diversity in surface and ground water. The replacement of the natural vegetation with millet fields and fallow increased the surface runoff, and consequently water accumulation in temporary pools and then CT3 recharge. In the SE part of the study area, the water table has risen up to outcropping in the lowest valley bottoms. These new permanent ponds reflect groundwater while temporary ponds still reflect surface dynamics. This new component of the hydrological landscape induces several consequences, in physical and human dimensions. Evaporation strongly affects the permanent water and increases its salinity while the natural mineralization of groundwater is very low. The easier access to water resources allows a significant development of local gardening, which modifies the social functioning of villages (e.g. land rights between villages and within a village, diversification of crops and sources of income, new sales channels). Different physically based models (for surface and ground water) were built, with a significant discrepancy between their respective quantification of water flows at the region scale. Extrapolation of surface fluxes from the few instrumented catchments to a much larger mosaic of non-instrumented catchments is only partially compatible with the geochemical and hydrodynamic calculations for the CT3 aquifer. This leads to many questions about the representativeness of instrumentation (in spite of dense observations), the heterogeneity of the landscape (perhaps even stronger than supposed, complementarities and differences between methods, etc.). Similarly, the diversity and evolution of human behaviours facing new situations (population growth, environmental changes) are essential elements to take into account, not always easily accessible to hydrologists.

A Stream Tilling Approach to Surface Area Estimation for Large Scale Spatial Data in a Shared Memory System

NASA Astrophysics Data System (ADS)

Liu, Jiping; Kang, Xiaochen; Dong, Chun; Xu, Shenghua

2017-12-01

Surface area estimation is a widely used tool for resource evaluation in the physical world. When processing large scale spatial data, the input/output (I/O) can easily become the bottleneck in parallelizing the algorithm due to the limited physical memory resources and the very slow disk transfer rate. In this paper, we proposed a stream tilling approach to surface area estimation that first decomposed a spatial data set into tiles with topological expansions. With these tiles, the one-to-one mapping relationship between the input and the computing process was broken. Then, we realized a streaming framework towards the scheduling of the I/O processes and computing units. Herein, each computing unit encapsulated a same copy of the estimation algorithm, and multiple asynchronous computing units could work individually in parallel. Finally, the performed experiment demonstrated that our stream tilling estimation can efficiently alleviate the heavy pressures from the I/O-bound work, and the measured speedup after being optimized have greatly outperformed the directly parallel versions in shared memory systems with multi-core processors.

Students' and Teachers' Application of Surface Area to Volume Relationships

ERIC Educational Resources Information Center

Taylor, Amy R.; Jones, M. Gail

2013-01-01

The "National Science Education Standards" emphasize teaching unifying concepts and processes such as basic functions of living organisms, the living environment, and scale (NRC 2011). Scale includes understanding that different characteristics, properties, or relationships within a system might change as its dimensions are increased or decreased…

Measuring contact area in a sliding human finger-pad contact.

PubMed

Liu, X; Carré, M J; Zhang, Q; Lu, Z; Matcher, S J; Lewis, R

2018-02-01

The work outlined in this paper was aimed at achieving further understanding of skin frictional behaviour by investigating the contact area between human finger-pads and flat surfaces. Both the static and the dynamic contact areas (in macro- and micro-scales) were measured using various techniques, including ink printing, optical coherence tomography (OCT) and Digital Image Correlation (DIC). In the studies of the static measurements using ink printing, the experimental results showed that the apparent and the real contact area increased with load following a piecewise linear correlation function for a finger-pad in contact with paper sheets. Comparisons indicated that the OCT method is a reliable and effective method to investigate the real contact area of a finger-pad and allow micro-scale analysis. The apparent contact area (from the DIC measurements) was found to reduce with time in the transition from the static phase to the dynamic phase while the real area of contact (from OCT) increased. The results from this study enable the interaction between finger-pads and contact object surface to be better analysed, and hence improve the understanding of skin friction. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Estimating surface fluxes over middle and upper streams of the Heihe River Basin with ASTER imagery

NASA Astrophysics Data System (ADS)

Ma, W.; Ma, Y.; Hu, Z.; Su, B.; Wang, J.; Ishikawa, H.

2009-06-01

Surface fluxes are important boundary conditions for climatological modeling and the Asian monsoon system. Recent availability of high-resolution, multi-band imagery from the ASTER (Advanced Space-borne Thermal Emission and Reflection Radiometer) sensor has enabled us to estimate surface fluxes to bridge the gap between local scale flux measurements using micrometeorological instruments and regional scale land-atmosphere exchanges of water and heat fluxes that are fundamental for the understanding of the water cycle in the Asian monsoon system. A Surface Energy Balance System (SEBS) method based on ASTER data and field observations has been proposed and tested for deriving net radiation flux (Rn), soil heat flux (G0), sensible heat flux (H) and latent heat flux (λ E) over heterogeneous land surface in this paper. As a case study, the methodology was applied to the experimental area of the WATER (Watershed Allied Telemetry Experimental Research), located at the mid-to-upstream sections of the Heihe River, northwest China. The ASTER data of 3 May and 4 June in 2008 was used in this paper for the case of mid-to-upstream sections of the Heihe River Basin. To validate the proposed methodology, the ground-measured land surface heat fluxes (net radiation flux (Rn), soil heat flux (G0), sensible heat flux (H) and latent heat flux (λ E)) were compared to the ASTER derived values. The results show that the derived surface variables and land surface heat fluxes in different months over the study area are in good accordance with the land surface status. It is therefore concluded that the proposed methodology is successful for the retrieval of land surface heat fluxes using the ASTER data and filed observation over the study area.

Finite element based contact analysis of radio frequency MEMs switch membrane surfaces

NASA Astrophysics Data System (ADS)

Liu, Jin-Ya; Chalivendra, Vijaya; Huang, Wenzhen

2017-10-01

Finite element simulations were performed to determine the contact behavior of radio frequency (RF) micro-electro-mechanical (MEM) switch contact surfaces under monotonic and cyclic loading conditions. Atomic force microscopy (AFM) was used to capture the topography of RF-MEM switch membranes and later they were analyzed for multi-scale regular as well as fractal structures. Frictionless, non-adhesive contact 3D finite element analysis was carried out at different length scales to investigate the contact behavior of the regular-fractal surface using an elasto-plastic material model. Dominant micro-scale regular patterns were found to significantly change the contact behavior. Contact areas mainly cluster around the regular pattern. The contribution from the fractal structure is not significant. Under cyclic loading conditions, plastic deformation in the 1st loading/unloading cycle smooth the surface. The subsequent repetitive loading/unloading cycles undergo elastic contact without changing the morphology of the contacting surfaces. The work is expected to shed light on the quality of the switch surface contact as well as the optimum design of RF MEM switch surfaces.

Process for forming a porous silicon member in a crystalline silicon member

DOEpatents

Northrup, M. Allen; Yu, Conrad M.; Raley, Norman F.

1999-01-01

Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific pore size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gasses in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased pressure for thermopneumatic actuation of integrated membranes. Examples that benefit from specific pore sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters.

The influence of a land-lake surface discontinuity on the convective boundary layer flow

NASA Astrophysics Data System (ADS)

Martinez, Daniel; Bange, Jens; Lang, Andreas

2013-04-01

The current work addresses the effects of surface discontinuities into the atmospheric boundary layer (ABL) with free convection using data collected during the STINHO 2002 and LITFASS 2003 experimental campaigns. These field experiments were performed during two consecutive summers in the area of Branderburg, Germany, over a heterogeneous area located around the Meteorological Observatory Lindenberg (MOL) of the German Weather Service (DWD). The terrain can be considered flat with areas of pine forests and agricultural fields, where lakes and villages are irregularly distributed to form a heterogeneous landscape representative of central Europe. Specific measurements collected by the helicopter-borne turbulence probe Helipod were selected to focus on the water-land surface transition over lake Scharnuetzel, a small-scale lake of 10 km x 2 km length scale. Four flights with a similar pattern were performed, with heights that range from 70 to 900 m above ground level (a.g.l.), in order to characterise the vertical extent of the surface discontinuity influence to the turbulent flow. The concepts of blending height and internal boundary layer (IBL) have been applied to the experimental data as a theoretical background. In general, the presence of the lake is reflected in the statistical second-order moments of the time series collected below 100 m a.g.l., specially for those time series related with the potential temperature. However, none of the parametrizations found in the literature related with the blending height or IBL seem to be appropriate for this special case, where a small-scale lake is the responsible of the surface heterogeneity. An analysis of the downstream propagation of the IBL depth shows that it depends on (i) the air stability downwind of the surface discontinuity and (ii) the wind speed in the surface layer. These preliminary results should be confirmed with the performance of new experiments.

Contact area of rough spheres: Large scale simulations and simple scaling laws

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pastewka, Lars, E-mail: lars.pastewka@kit.edu; Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218; Robbins, Mark O., E-mail: mr@pha.jhu.edu

2016-05-30

We use molecular simulations to study the nonadhesive and adhesive atomic-scale contact of rough spheres with radii ranging from nanometers to micrometers over more than ten orders of magnitude in applied normal load. At the lowest loads, the interfacial mechanics is governed by the contact mechanics of the first asperity that touches. The dependence of contact area on normal force becomes linear at intermediate loads and crosses over to Hertzian at the largest loads. By combining theories for the limiting cases of nominally flat rough surfaces and smooth spheres, we provide parameter-free analytical expressions for contact area over the wholemore » range of loads. Our results establish a range of validity for common approximations that neglect curvature or roughness in modeling objects on scales from atomic force microscope tips to ball bearings.« less

Noise characteristics of upper surface blown configurations. Experimental program and results

NASA Technical Reports Server (NTRS)

Brown, W. H.; Searle, N.; Blakney, D. F.; Pennock, A. P.; Gibson, J. S.

1977-01-01

An experimental data base was developed from the model upper surface blowing (USB) propulsive lift system hardware. While the emphasis was on far field noise data, a considerable amount of relevant flow field data were also obtained. The data were derived from experiments in four different facilities resulting in: (1) small scale static flow field data; (2) small scale static noise data; (3) small scale simulated forward speed noise and load data; and (4) limited larger-scale static noise flow field and load data. All of the small scale tests used the same USB flap parts. Operational and geometrical variables covered in the test program included jet velocity, nozzle shape, nozzle area, nozzle impingement angle, nozzle vertical and horizontal location, flap length, flap deflection angle, and flap radius of curvature.

Quantifying object and material surface areas in residences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hodgson, Alfred T.; Ming, Katherine Y.; Singer, Brett C.

2005-01-05

The dynamic behavior of volatile organic compounds (VOCs) in indoor environments depends, in part, on sorptive interactions between VOCs in the gas phase and material surfaces. Since information on the types and quantities of interior material surfaces is not generally available, this pilot-scale study was conducted in occupied residences to develop and demonstrate a method for quantifying surface areas of objects and materials in rooms. Access to 33 rooms in nine residences consisting of bathrooms, bedroom/offices and common areas was solicited from among research group members living in the East San Francisco Bay Area. A systematic approach was implemented formore » measuring rooms and objects from 300 cm{sup 2} and larger. The ventilated air volumes of the rooms were estimated and surface area-to-volume ratios were calculated for objects and materials, each segregated into 20 or more categories. Total surface area-to-volume ratios also were determined for each room. The bathrooms had the highest total surface area-to-volume ratios. Bedrooms generally had higher ratios than common areas consisting of kitchens, living/dining rooms and transitional rooms. Total surface area-to-volume ratios for the 12 bedrooms ranged between 2.3 and 4.7 m{sup 2} m{sup -3}. The importance of individual objects and materials with respect to sorption will depend upon the sorption coefficients for the various VOC/materials combinations. When combined, the highly permeable material categories, which may contribute to significant interactions, had a median ratio of about 0.5 m{sup 2} m{sup -3} for all three types of rooms.« less

Acoustic scale modelling of factories, part II: 1-50 Cale model investigations of factory sound fields

NASA Astrophysics Data System (ADS)

Hodgson, M. R.; Orlowski, R. J.

1987-03-01

In this second part of a report on factory scale modelling use of a 1:50 scale variable model as a research tool is described. Details of the model are presented. The results of measurements of reverberation time and sound propagation, made in various model configurations, are used to investigate the main factors influencing factory sound fields, and the applicability of the Sabine theory to factories. The parameters investigated are the enclosure geometry (aspect ratio, volume and roof pitch), surface absorption and fittings (density, size, surface area, vertical distribution and specific types). Despite certain limitations and uncertainties resulting, for example, from surprising results associated with surface absorption, models are shown to be effective research tools. The inapplicability of the Sabine theory is confirmed and elucidated.

Comparative Study of Lunar Roughness from Multi - Source Data

NASA Astrophysics Data System (ADS)

Lou, Y.; Kang, Z.

2017-07-01

The lunar terrain can show its collision and volcanic history. The lunar surface roughness can give a deep indication of the effects of lunar surface magma, sedimentation and uplift. This paper aims to get different information from the roughness through different data sources. Besides introducing the classical Root-mean-square height method and Morphological Surface Roughness (MSR) algorithm, this paper takes the area of the Jurassic mountain uplift in the Sinus Iridum and the Plato Crater area as experimental areas. And then make the comparison and contrast of the lunar roughness derived from LRO's DEM and CE-2 DOM. The experimental results show that the roughness obtained by the traditional roughness calculation method reflect the ups and downs of the topography, while the results obtained by morphological surface roughness algorithm show the smoothness of the lunar surface. So, we can first use the surface fluctuation situation derived from RMSH to select the landing area range which ensures the lands are gentle. Then the morphological results determine whether the landing area is suitable for the detector walking and observing. The results obtained at two different scales provide a more complete evaluation system for selecting the landing site of the lunar probe.

Using pan-sharpened high resolution satellite data to improve impervious surfaces estimation

NASA Astrophysics Data System (ADS)

Xu, Ru; Zhang, Hongsheng; Wang, Ting; Lin, Hui

2017-05-01

Impervious surface is an important environmental and socio-economic indicator for numerous urban studies. While a large number of researches have been conducted to estimate the area and distribution of impervious surface from satellite data, the accuracy for impervious surface estimation (ISE) is insufficient due to high diversity of urban land cover types. This study evaluated the use of panchromatic (PAN) data in very high resolution satellite image for improving the accuracy of ISE by various pan-sharpening approaches, with a further comprehensive analysis of its scale effects. Three benchmark pan-sharpening approaches, Gram-Schmidt (GS), PANSHARP and principal component analysis (PCA) were applied to WorldView-2 in three spots of Hong Kong. The on-screen digitization were carried out based on Google Map and the results were viewed as referenced impervious surfaces. The referenced impervious surfaces and the ISE results were then re-scaled to various spatial resolutions to obtain the percentage of impervious surfaces. The correlation coefficient (CC) and root mean square error (RMSE) were adopted as the quantitative indicator to assess the accuracy. The accuracy differences between three research areas were further illustrated by the average local variance (ALV) which was used for landscape pattern analysis. The experimental results suggested that 1) three research regions have various landscape patterns; 2) ISE accuracy extracted from pan-sharpened data was better than ISE from original multispectral (MS) data; and 3) this improvement has a noticeable scale effects with various resolutions. The improvement was reduced slightly as the resolution became coarser.

Pilot Scale Production of Activated Carbon Spheres Using Fluidized Bed Reactor and Its Evaluation for the Removal of Hexavalent Chromium from Aqueous Solutions

NASA Astrophysics Data System (ADS)

Tripathi, Nagesh Kumar; Sathe, Manisha

2017-12-01

Large scale production of activated carbon is need of ongoing research due to its excellent adsorption capacity for removal of heavy metals from contaminated solutions. In the present study, polymeric precursor polystyrene beads [Brunauer Emmett Teller (BET) surface area, 46 m2/g; carbon content, 40.64%; crushing strength, 0.32 kg/sphere] were used to produce a new variant of activated carbon, Activated Carbon Spheres (ACS) in a pilot scale fluidized bed reactor. ACS were prepared by carbonization of polymeric precursor at 850 °C followed by activation of resultant material with steam. Prepared ACS were characterized using scanning electron microscope, CHNS analyzer, thermogravimetric analyzer, surface area analyzer and crushing strength tester. The produced ACS have 1009 m2/g BET surface area, 0.89 cm3/g total pore volume, 92.32% carbon content and 1.1 kg/sphere crushing strength with less than 1% of moisture and ash content. The ACS were also evaluated for its potential to remove hexavalent chromium [Cr(VI)] from contaminated solutions. The chromium removal is observed to be 99.1% at initial concentration 50 mg/l, pH 2, ACS dose 1 g/l, contact time 2 h, agitation 120 rpm and temperature 30 °C. Thus ACS can be used as an adsorbent material for the removal of Cr(VI) from contaminated solutions.

Meso and micro-scale response of post carbon removal nitrifying MBBR biofilm across carrier type and loading.

PubMed

Young, Bradley; Banihashemi, Bahman; Forrest, Daina; Kennedy, Kevin; Stintzi, Alain; Delatolla, Robert

2016-03-15

This study investigates the effects of three specific moving bed biofilm reactor (MBBR) carrier types and two surface area loading rates on biofilm thickness, morphology and bacterial community structure of post carbon removal nitrifying MBBR systems along with the effects of carrier type and loading on ammonia removal rates and effluent solids settleability. The meso and micro analyses show that the AOB kinetics vary based on loading condition, but irrespective of carrier type. The meso-scale response to increases in loading was shown to be an increase in biofilm thickness with higher surface area carriers being more inclined to develop and maintain thicker biofilms. The pore spaces of these higher surface area to volume carriers also demonstrated the potential to become clogged at higher loading conditions. Although the biofilm thickness increased during higher loading conditions, the relative percentages of both the embedded viable and non-viable cells at high and conventional loading conditions remained stable; indicating that the reduced ammonia removal kinetics observed during carrier clogging events is likely due to the observed reduction in the surface area of the attached biofilm. Microbial community analyses demonstrated that the dominant ammonia oxidizing bacteria for all carriers is Nitrosomonas while the dominant nitrite oxidizing bacteria is Nitrospira. The research showed that filamentous species were abundant under high loading conditions, which likely resulted in the observed reduction in effluent solids settleability at high loading conditions as opposed to conventional loading conditions. Although the settleability of the effluent solids was correlated to increases in abundances of filamentous organisms in the biofilm, analyzed using next generation sequencing, the ammonia removal rate was not shown to be directly correlated to specific meso or micro-scale characteristics. Instead post carbon removal MBBR ammonia removal kinetics were shown to be related to the viable AOB cell coverage of the carriers; which was calculated by normalizing the surface area removal rate by the biofilm thickness, the bacterial percent abundance of ammonia oxidizing bacteria and the percentage of viable cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of Precipitation on Ocean Mixed-Layer Temperature and Salinity as Simulated in a 2-D Coupled Ocean-Cloud Resolving Atmosphere Model

NASA Technical Reports Server (NTRS)

Li, Xiaofan; Sui, C.-H.; Lau, K-M.; Adamec, D.

1999-01-01

A two-dimensional coupled ocean-cloud resolving atmosphere model is used to investigate possible roles of convective scale ocean disturbances induced by atmospheric precipitation on ocean mixed-layer heat and salt budgets. The model couples a cloud resolving model with an embedded mixed layer-ocean circulation model. Five experiment are performed under imposed large-scale atmospheric forcing in terms of vertical velocity derived from the TOGA COARE observations during a selected seven-day period. The dominant variability of mixed-layer temperature and salinity are simulated by the coupled model with imposed large-scale forcing. The mixed-layer temperatures in the coupled experiments with 1-D and 2-D ocean models show similar variations when salinity effects are not included. When salinity effects are included, however, differences in the domain-mean mixed-layer salinity and temperature between coupled experiments with 1-D and 2-D ocean models could be as large as 0.3 PSU and 0.4 C respectively. Without fresh water effects, the nocturnal heat loss over ocean surface causes deep mixed layers and weak cooling rates so that the nocturnal mixed-layer temperatures tend to be horizontally-uniform. The fresh water flux, however, causes shallow mixed layers over convective areas while the nocturnal heat loss causes deep mixed layer over convection-free areas so that the mixed-layer temperatures have large horizontal fluctuations. Furthermore, fresh water flux exhibits larger spatial fluctuations than surface heat flux because heavy rainfall occurs over convective areas embedded in broad non-convective or clear areas, whereas diurnal signals over whole model areas yield high spatial correlation of surface heat flux. As a result, mixed-layer salinities contribute more to the density differences than do mixed-layer temperatures.

An LES study on the spatial variability impact of surface sensible heat flux (SHF) on the convective boundary layer (CBL)

NASA Astrophysics Data System (ADS)

Kang, S. L.; Chun, J.; Kumar, A.

2015-12-01

We study the spatial variability impact of surface sensible heat flux (SHF) on the convective boundary layer (CBL), using the Weather Research and Forecasting (WRF) model in large eddy simulation (LES) mode. In order to investigate the response of the CBL to multi-scale feature of the surface SHF field over a local area of several tens of kilometers or smaller, an analytic surface SHF map is crated as a function of the chosen feature. The spatial variation in the SHF map is prescribed with a two-dimensional analytical perturbation field, which is generated by using the inverse transform technique of the Fourier series whose coefficients are controlled, of which spectrum to have a particular slope in the chosen range of wavelength. Then, the CBL responses to various SHF heterogeneities are summarized as a function of the spectral slope, in terms of mean structure, turbulence statistics and cross-scale processes. The range of feasible SHF heterogeneities is obtained from the SHF maps produced by a land surface model (LSM) of the WRF system. The LSM-derived SHF maps are a function of geographical data on various resolutions. Based on the numerical experiment results with the surface heterogeneities in the range, we will discuss the uncertainty in the SHF heterogeneity and its impact on the atmosphere in a numerical model. Also we will present the range of spatial scale of the surface SHF heterogeneity that significantly influence on the whole CBL. Lastly, we will report the test result of the hypothesis that the spatial variability of SHF is more representative of surface thermal heterogeneity than is the latent heat flux over the local area of several tens of kilometers or smaller.

An approach for mapping large-area impervious surfaces: Synergistic use of Landsat-7 ETM+ and high spatial resolution imagery

USGS Publications Warehouse

Yang, Limin; Huang, Chengquan; Homer, Collin G.; Wylie, Bruce K.; Coan, Michael

2003-01-01

A wide range of urban ecosystem studies, including urban hydrology, urban climate, land use planning, and resource management, require current and accurate geospatial data of urban impervious surfaces. We developed an approach to quantify urban impervious surfaces as a continuous variable by using multisensor and multisource datasets. Subpixel percent impervious surfaces at 30-m resolution were mapped using a regression tree model. The utility, practicality, and affordability of the proposed method for large-area imperviousness mapping were tested over three spatial scales (Sioux Falls, South Dakota, Richmond, Virginia, and the Chesapeake Bay areas of the United States). Average error of predicted versus actual percent impervious surface ranged from 8.8 to 11.4%, with correlation coefficients from 0.82 to 0.91. The approach is being implemented to map impervious surfaces for the entire United States as one of the major components of the circa 2000 national land cover database.

Final Stages of the 1:24,000-Scale Geologic Mapping of Basin Deposits Exposed in Hadriacus Cavi, Mars

NASA Astrophysics Data System (ADS)

Skinner, J. A.; Fortezzo, C. M.

2018-06-01

This abstract presents a brief summary of the surface and section characteristics of a type area for stratified deposits exposed in Hadriacus Cavi (78.0°E, –27.3°N), Mars based on 1:24,000 scale geologic mapping and stratigraphic analyses.

Surface Rupture Effects on Earthquake Moment-Area Scaling Relations

NASA Astrophysics Data System (ADS)

Luo, Yingdi; Ampuero, Jean-Paul; Miyakoshi, Ken; Irikura, Kojiro

2017-09-01

Empirical earthquake scaling relations play a central role in fundamental studies of earthquake physics and in current practice of earthquake hazard assessment, and are being refined by advances in earthquake source analysis. A scaling relation between seismic moment ( M 0) and rupture area ( A) currently in use for ground motion prediction in Japan features a transition regime of the form M 0- A 2, between the well-recognized small (self-similar) and very large (W-model) earthquake regimes, which has counter-intuitive attributes and uncertain theoretical underpinnings. Here, we investigate the mechanical origin of this transition regime via earthquake cycle simulations, analytical dislocation models and numerical crack models on strike-slip faults. We find that, even if stress drop is assumed constant, the properties of the transition regime are controlled by surface rupture effects, comprising an effective rupture elongation along-dip due to a mirror effect and systematic changes of the shape factor relating slip to stress drop. Based on this physical insight, we propose a simplified formula to account for these effects in M 0- A scaling relations for strike-slip earthquakes.

Study of free edge effect on sub-laminar scale for thermoplastic composite laminates

NASA Astrophysics Data System (ADS)

Shen, Min; Lu, Huanbao; Tong, Jingwei; Su, Yishi; Li, Hongqi; Lv, Yongmin

2008-11-01

The interlaminar deformation on the free edge surface in thermoplastic composite AS4/PEEK laminates under bending loading are studied by means of digital image correlation method (DICM) using a white-light industrial microscopic. During the test, any artificial stochastic spray is not applied to the specimen surface. In laminar scale, the interlaminare displacements of [0/90]3s laminate are measured. In sub-laminar scale, the tested area includes a limited number of fibers; the fiber is elastic with actual diameter about 7μm, and PEEK matrix has elastic-plastic behavior. The local mesoscopic fields of interlaminar displacement near the areas of fiber-matrix interface are obtained by DICM. The distributions of in-plane elastic-plastic stresses near the interlaminar interface between different layers are indirectly obtained using the coupling the results of DICM with finite element method. Based on above DICM experiments, the influences of random fiber distribution and the PEEK matrix ductility in sub-laminar scale on the ineterlaminar mesomechanical behavior are investigated. The experimental results in the present work are important for multi-scale theory and numerical analysis of interlaminar deformation and stresses in these composite laminates.

Investigating failure behavior and origins under supposed "shear bond" loading.

PubMed

Sultan, Hassam; Kelly, J Robert; Kazemi, Reza B

2015-07-01

This study evaluated failure behavior when resin-composite cylinders bonded to dentin fractured under traditional "shear" testing. Failure was assessed by scaling of failure loads to changes in cylinder radii and fracture surface analysis. Three stress models were examined including failure by: bonded area; flat-on-cylinder contact; and, uniformly-loaded, cantilevered-beam. Nine 2-mm dentin occlusal dentin discs for each radii tested were embedded in resin and bonded to resin-composite cylinders; radii (mm)=0.79375; 1.5875; 2.38125; 3.175. Samples were "shear" tested at 1.0mm/min. Following testing, disks were finished with silicone carbide paper (240-600grit) to remove residual composite debris and tested again using different radii. Failure stresses were calculated for: "shear"; flat-on-cylinder contact; and, bending of a uniformly-loaded cantilevered beam. Stress equations and constants were evaluated for each model. Fracture-surface analysis was performed. Failure stresses calculated as flat-on-cylinder contact scaled best with its radii relationship. Stress equation constants were constant for failure from the outside surface of the loaded cylinders and not with the bonded surface area or cantilevered beam. Contact failure stresses were constant over all specimen sizes. Fractography reinforced that failures originated from loaded cylinder surface and were unrelated to the bonded surface area. "Shear bond" testing does not appear to test the bonded interface. Load/area "stress" calculations have no physical meaning. While failure is related to contact stresses, the mechanism(s) likely involve non-linear damage accumulation, which may only indirectly be influenced by the interface. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Changes in ectocervical surface area in women throughout pregnancy compared to non-pregnant and postpartum states.

PubMed

Qian, Xueya; Jiang, Yanmin; Liu, Lei; Shi, Shao-Qing; Garfield, Robert E; Liu, Huishu

2016-11-01

The objective of this study is to estimate changes in the surface area of the ectocervix (CA) in women during pregnancy and compare this to postpartum and non-pregnant states. CA was evaluated in 210 normal nulliparous women divided into groups from early to late gestation, 40 postpartum women, and 25 non-pregnant women. CA in cm(2) was estimated from analysis of images taken with an endoscope of the cervical face and an mm scale. An mm scale was also used to determine fornix length and fornix area computed. The face, fornix, and total areas of the CA of non-pregnant and postpartum groups are significantly smaller (p < 0.001) than these areas in groups during pregnancy. Generally, the CA of the face, fornix, and total area are also less in early pregnancy compared with late gestation (p < 0.01 to <0.001). Total CA correlates with gestational age (r = 0.196, p < 0.004). (1) During pregnancy, CA slowly and progressively increases to >75% area compared with CA of non-pregnant patients and then reverts back to low CA postpartum. (2) Increases in CA during pregnancy occur in both the face and fornix areas. (3) Increases in CA reflect enlargement in cervical volume and remodeling during pregnancy.

Characterization of self-affinity in the global regime

NASA Astrophysics Data System (ADS)

Neimark, Alexander V.

1994-11-01

Methods for characterization of self-affine surfaces and measurements of their roughness exponents H are developed. It is shown that for smoothed surfaces, which underwent particular coarse graining or averaging of the small-scale fluctuations, the excess surface area Sex and the mean square root radius of curvature ac are related by two distinct asymptotic power laws if ac is well below or well above a certain crossover scale acr. In the local regime of self-affinity, when ac<>acr, Sex~(ac/acr)-2(1-H)/(2-H). The former scaling relationship is consistent with the well known definition of local fractal dimensions dloc=dtop+1-H. The latter scaling relationship offers alternatives for characterization of self-affinity over large scales by means of excess dimensions defined as dex=dtop+2(1-H)/(2-H) and can be used for determination of roughness exponents from the measurements provided in the global regime. The thermodynamic method of fractal analysis, proposed earlier for self-similar surfaces (A.V. Neimark, Pis'ma Zh. Eksp. Teor. Fiz. 51, 535 (1990) [JETP Lett. 51, 607 (1990)]; Physica A 191, 258 (1992)), is extended for self-affine surfaces for determination of fractal dimensions and roughness exponents from adsorption and capillary experimental data.

Differential contributions of cortical thickness and surface area to trait impulsivity in healthy young adults.

PubMed

Kubera, Katharina M; Schmitgen, Mike M; Maier-Hein, Klaus H; Thomann, Philipp A; Hirjak, Dusan; Wolf, Robert C

2018-05-08

Impulsivity is an essential human personality trait and highly relevant for the development of several mental disorders. There is evidence that impulsivity is heritable, yet little is known about neural correlates reflecting early brain development. Here, we address the question whether motor, attentional and non-planning components, as reflected by the Barratt Impulsiveness Scale (BIS-11), are distinctly associated with cortical thickness and surface area variations in young healthy individuals. We investigated cortical thickness and surface area in 54 healthy volunteers (m/f = 30%/70%; age mean/SD = 24.9/4.02) using structural magnetic resonance imaging at 3 T together with surface-based analysis techniques. Impulsivity was examined on the Barratt impulsiveness scale (BIS-11) and related to the two distinct cortical measurements. Higher BIS-11 total scores were negatively associated with cortical thickness variations in the left lingual gyrus, left superior temporal gyrus, right cuneus, and right superior parietal gyrus (p<0.05 cluster-wise probability [CWP] corrected). Higher BIS-11 nonplanning scores were negatively associated with cortical thickness variations in bilateral pericalcarine gyrus (p<0.05 CWP corr.). In the orbitofrontal cortex motor impulsivity associated cortical thickness differs significantly between male and female. These data suggest distinct neurodevelopmental trajectories underlying impulsivity in healthy subjects. Impulsivity total scores appear to be specifically related to cortical thickness variations, in contrast to variations of cortical surface area. Furthermore, our findings underscores the importance of better characterizing gender-specific structural correlates of impulsivity. Copyright © 2018. Published by Elsevier B.V.

Application and Evaluation of MODIS LAI, fPAR, and Albedo Products in the WRFCMAQ System

EPA Science Inventory

Leaf area index (LAI), vegetation fraction (VF), and surface albedo are important parameters in the land surface model (LSM) for meteorology and air quality modeling systems such as WRF/CMAQ. LAI and VF control not only leaf to canopy level evapotranspiration flux scaling but al...

High-resolution simulation of heatwave events in New York City

NASA Astrophysics Data System (ADS)

Ramamurthy, P.; Li, D.; Bou-Zeid, E.

2017-04-01

Heatwave intensity and frequency are predicted to increase in the coming years, and this will bear adverse consequences to the environmental well-being and the socio-economic fabric in urbanized areas. The hazardous combination of increased heat storage and reduced water retention capacities of the land surface make the urban areas warmer than the surrounding rural areas in what is commonly known as the urban heat island (UHI) effect. The primary motives of this study are to quantify the interaction of this city-scale UHI with synoptic-scale heatwave episodes and to analyze the factors that mediate this interaction. A modified version of the Weather Research and Forecasting model (WRF) is utilized to simulate two heatwave episodes in New York City. The land surface scheme in the default WRF model is modified to better represent the surface to atmosphere exchanges over urban areas. Our results indicate that during the heatwave episodes, the daily-averaged UHI in NYC increased by 1.5 K. Furthermore, most of this amplification occurs in the mid-afternoon period when the temperatures peak. Wind direction and urban-rural contrasts in available energy and moisture availability are found to have significant and systematic effects on the UHI, but wind speed plays a secondary role.

Beyond greening and browning: the need for an integrated understanding of Arctic change

NASA Astrophysics Data System (ADS)

Gamon, J. A.; Huemmrich, K. F.; Hmimina, G.; Yu, R.

2017-12-01

Satellite records and field observations povide contradictory evidence for "greening" or "browning" of Arctic tundra. Large-scale observations of apparent greening have been based on satellite vegetation indices (e.g NDVI). However, a clear interpretation of these trends are confounded by changing snow cover and surface hydrology, both of which influence NDVI and are known to be changing independently of any direct vegetation response. Field studies have demonstrated greening in some areas, but not others, and have also documented changing permafrost depth, surface hydrology and snow cover. Together, these confounding factors can explain some of the contradictory evidence based regarding greening and browning. Given the multiple influences on Arctic NDVI, simple conclusions regarding greening and browning from satellite data alone can be incorrect; when these confounding factors are taken into account, some areas that show apparent greening in the satellite record appear to be undergoing productivity declines due to surface drying. These contradictory interpretations have profound implications for our understanding of changing surface energy balance, biogeochemistry, and surface-atmosphere feedbacks. To better address Arctic ecosystem responses to a changing climate, an integrated, multi-scale, multivariate approach that considers hydrology, permafrost, snow cover and vegetation is needed.

Quasi-ballistic Electronic Thermal Conduction in Metal Inverse Opals.

PubMed

Barako, Michael T; Sood, Aditya; Zhang, Chi; Wang, Junjie; Kodama, Takashi; Asheghi, Mehdi; Zheng, Xiaolin; Braun, Paul V; Goodson, Kenneth E

2016-04-13

Porous metals are used in interfacial transport applications that leverage the combination of electrical and/or thermal conductivity and the large available surface area. As nanomaterials push toward smaller pore sizes to increase the total surface area and reduce diffusion length scales, electron conduction within the metal scaffold becomes suppressed due to increased surface scattering. Here we observe the transition from diffusive to quasi-ballistic thermal conduction using metal inverse opals (IOs), which are metal films that contain a periodic arrangement of interconnected spherical pores. As the material dimensions are reduced from ∼230 nm to ∼23 nm, the thermal conductivity of copper IOs is reduced by more than 57% due to the increase in surface scattering. In contrast, nickel IOs exhibit diffusive-like conduction and have a constant thermal conductivity over this size regime. The quasi-ballistic nature of electron transport at these length scales is modeled considering the inverse opal geometry, surface scattering, and grain boundaries. Understanding the characteristics of electron conduction at the nanoscale is essential to minimizing the total resistance of porous metals for interfacial transport applications, such as the total electrical resistance of battery electrodes and the total thermal resistance of microscale heat exchangers.

Spatial heterogeneity of leaf area index across scales from simulation and remote sensing

NASA Astrophysics Data System (ADS)

Reichenau, Tim G.; Korres, Wolfgang; Montzka, Carsten; Schneider, Karl

2016-04-01

Leaf area index (LAI, single sided leaf area per ground area) influences mass and energy exchange of vegetated surfaces. Therefore LAI is an input variable for many land surface schemes of coupled large scale models, which do not simulate LAI. Since these models typically run on rather coarse resolution grids, LAI is often inferred from coarse resolution remote sensing. However, especially in agriculturally used areas, a grid cell of these products often covers more than a single land-use. In that case, the given LAI does not apply to any single land-use. Therefore, the overall spatial heterogeneity in these datasets differs from that on resolutions high enough to distinguish areas with differing land-use. Detailed process-based plant growth models simulate LAI for separate plant functional types or specific species. However, limited availability of observations causes reduced spatial heterogeneity of model input data (soil, weather, land-use). Since LAI is strongly heterogeneous in space and time and since processes depend on LAI in a nonlinear way, a correct representation of LAI spatial heterogeneity is also desirable on coarse resolutions. The current study assesses this issue by comparing the spatial heterogeneity of LAI from remote sensing (RapidEye) and process-based simulations (DANUBIA simulation system) across scales. Spatial heterogeneity is assessed by analyzing LAI frequency distributions (spatial variability) and semivariograms (spatial structure). Test case is the arable land in the fertile loess plain of the Rur catchment near the Germany-Netherlands border.

An analysis of the impacts of global climate and emissions changes on regional tropospheric ozone

NASA Technical Reports Server (NTRS)

John, Kuruvilla; Crist, Kevin C.; Carmichael, Gregory R.

1994-01-01

Many of the synergistic impacts resulting from future changes in emissions as well as changes in ambient temperature, moisture, and UV flux have not been quantified. A three-dimensional regional-scale photo-chemical model (STEM-2) is used in this study to evaluate these perturbations to trace gas cycles over the eastern half of the United States of America. The model was successfully used to simulate a regional-scale ozone episode (base case - June 1984) and four perturbations scenarios - viz., perturbed emissions, temperature, water vapor column, and incoming UV flux cases, and a future scenario (for the year 2034). The impact of these perturbation scenarios on the distribution of ozone and other major pollutants such as SO2 and sulfates were analyzed in detail. The spatial distribution and the concentration of ozone at the surface increased by about 5-15 percent for most cases except for the perturbed water vapor case. The regional scale surface ozone concentration distribution for the year 2034 (future scenario) showed an increase of non-attainment areas. The rural areas of Pennsylvania, West Virginia, and Georgia showed the largest change in the surface ozone field for the futuristic scenario when compared to the base case.

Algorithm of regional surface evaporation using remote sensing: A case study of Haihe basin, China

NASA Astrophysics Data System (ADS)

Xiong, Jun; Wu, Bingfang; Yan, Nana; Hu, Minggang

2007-11-01

Evapotranspiration (ET, or latent heat flux) is the most essential and uncertain factor in water resource management. Remote sensing is a promising tool for estimation of spatial distribution of ET at regional scale with limited ground observations. We developed an algorithm for estimating regional evapotranspiration from MODIS 1b data and ancillary meteorological data. The algorithm is an integration of Penman-Monteith equation and SEBS (Surface Energy Balance System) model. The former is a combination of the energy balance theory and the mass transfer method to compute the evaporation from cropped surfaces from standard climatological records of sunshine, temperature, humidity and wind speed by introducing resistance factors, and the latter determines the spatio-temporal variability of regional evaporative condition. First, we characterized key land surface parameters on satellite over passing days, including fractional vegetation cover (fc), roughness height for momentum (z0m), net radiation (Rn) and soil heat flux (G0); Second, SEBS was applied to partition the sensible heat (H) from latent heat (LE) in combination with Planetary Boundary Layer (PBL) information from seven meteorological stations. A parameterization of surface roughness was applied at mountainous area considering topographic influence; third, we chose available surface resistance (RS) as the temporal-scaling factor. With bulk surface resistance is properly defined, P-M methods is valid for both soil and vegetation canopy. We validated ET from this algorithm with limited actual observations of ET including 2 eddy covariance system dataset and 1 lysimeter sites. Water balance equation is used as a trend-analysis tool to show the consistency between rainfall and ET on four drainage area. As a result, the prototype products showed different accuracy and applicability on different underlying and time scale, which demonstrates the potential of this approach for estimating ET from 1-km to regional spatial scale in North China Plain.

Characterizing the fabric of the urban environment: A case study of Salt Lake City, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akbari, Hashem; Rose, L. Shea

2001-02-28

Urban fabric data are needed in order to estimate the impact of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city, and to design effective implementation programs. In this report, we discuss the result of a semi-automatic Monte-Carlo statistical approach used to develop data on surface-type distribution and city-fabric makeup (percentage of various surface-types) using aerial color orthophotography. The digital aerial photographs for Salt Lake City covered a total of about 34 km2 (13 mi2). At 0.50-m resolution, there were approximately 1.4 x 108 pixels of data. Four majormore » land-use types were examined: (1) commercial, (2) industrial, (3) educational, and (4) residential. On average, for the areas studied, vegetation covers about 46 percent of the area (ranging 44-51 percent), roofs cover about 21 percent (ranging 15-24 percent), and paved surfaces about 26 percent (ranging 21-28 percent). For the most part, trees shade streets, parking lots, grass, and sidewalks. In most non-residential areas, paved surfaces cover 46-66 percent of the area. In residential areas, on average, paved surfaces cover about 32 percent of the area. Land-use/land-cover (LU/LC) data from the United States Geological Survey were used to extrapolate these results from neighborhood scales to metropolitan Salt Lake City. In an area of roughly 560 km2, defining most of metropolitan Salt Lake City, over 60 percent is residential. The total roof area is about 110 km2, and the total paved surface area (roads, parking areas, sidewalks) covers about 170 km2. The total vegetated area covers about 230 km2.« less

Use of Patient and Observer Scar Assessment Scale for evaluation of facial scars treated with self-drying silicone gel.

PubMed

Bianchi, Francesca A; Roccia, Fabio; Fiorini, Paola; Berrone, Sid

2010-05-01

In this prospective study, we used the Patient and Observer Scar Assessment Scale (POSAS) to evaluate the outcome of the healing process of posttraumatic and surgical facial scars that were treated with self-drying silicone gel, by both the patient and the observer. In our division, the application of base cream and massage represents the standard management of facial scars after suture removal. In the current study, 15 patients (7 men and 8 women) with facial scars were treated with self-drying silicone gel that was applied without massage, and 15 patients (8 men and 7 women) were treated with base cream and massage. Both groups underwent a clinical evaluation of facial scars by POSAS at the time of suture removal (T0) and after 2 months of treatment (T1). The patient rated scar pain, itch, color, stiffness, thickness, and surface (Patient Scale), and the observer rated scar vascularity, pigmentation, thickness, relief, pliability, and surface area (Observer Scale [OS]). The Patient Scale reported the greatest improvement in the items color, stiffness, and thickness. Itch was the only item that worsened in the group self-drying silicone gel. The OS primarily reported an improvement in the items vascularization, pigmentation, and pliability. The only item in the OS that underwent no change from T0 to T1 was surface area. The POSAS revealed satisfactory healing of posttraumatic and surgical facial scars that were treated with self-drying silicone gel.

Edge-to-Stem Variability in Wet-Canopy Evaporation From an Urban Tree Row

NASA Astrophysics Data System (ADS)

Van Stan, John T.; Norman, Zachary; Meghoo, Adrian; Friesen, Jan; Hildebrandt, Anke; Côté, Jean-François; Underwood, S. Jeffrey; Maldonado, Gustavo

2017-11-01

Evaporation from wet-canopy (E_C) and stem (E_S) surfaces during rainfall represents a significant portion of municipal-to-global scale hydrologic cycles. For urban ecosystems, E_C and E_S dynamics play valuable roles in stormwater management. Despite this, canopy-interception loss studies typically ignore crown-scale variability in E_C and assume (with few indirect data) that E_S is generally {<}2% of total wet-canopy evaporation. We test these common assumptions for the first time with a spatially-distributed network of in-canopy meteorological monitoring and 45 surface temperature sensors in an urban Pinus elliottii tree row to estimate E_C and E_S under the assumption that crown surfaces behave as "wet bulbs". From December 2015 through July 2016, 33 saturated crown periods (195 h of 5-min observations) were isolated from storms for determination of 5-min evaporation rates ranging from negligible to 0.67 mm h^{-1}. Mean E_S (0.10 mm h^{-1}) was significantly lower (p < 0.01) than mean E_C (0.16 mm h^{-1}). But, E_S values often equalled E_C and, when scaled to trunk area using terrestrial lidar, accounted for 8-13% (inter-quartile range) of total wet-crown evaporation (E_S+E_C scaled to surface area). E_S contributions to total wet-crown evaporation maximized at 33%, showing a general underestimate (by 2-17 times) of this quantity in the literature. Moreover, results suggest wet-crown evaporation from urban tree rows can be adequately estimated by simply assuming saturated tree surfaces behave as wet bulbs, avoiding problematic assumptions associated with other physically-based methods.

Widespread surface meltwater drainage in Antarctica

NASA Astrophysics Data System (ADS)

Kingslake, J.; Ely, J.; Das, I.; Bell, R. E.

2016-12-01

Surface meltwater is thought to cause ice-shelf disintegration, which accelerates the contribution of ice sheets to sea-level rise. Antarctic surface melting is predicted to increase and trigger further ice-shelf disintegration during this century. These climate-change impacts could be modulated by an active hydrological network analogous to the one in operation in Greenland. Despite some observations of Antarctic surface and sub-surface hydrological systems, large-scale active surface drainage in Antarctica has rarely been studied. We use satellite imagery and aerial photography to reveal widespread active hydrology on the surface of the Antarctic Ice Sheet as far south as 85o and as high as 1800 m a.s.l., often near mountain peaks that protrude through the ice (nunataks) and relatively low-albedo `blue-ice areas'. Despite predominantly sub-zero regional air temperatures, as simulated by a regional climate model, Antarctic active drainage has persisted for decades, transporting water through surface streams and feeding vast melt ponds up to 80 km long. Drainage networks (the largest are over 100 km in length) form on flat ice shelves, steep outlet glaciers and ice-sheet flanks across the West and East Antarctica Ice Sheets. Motivated by the proximity of many drainage systems to low-albedo rock and blue-ice areas, we hypothesize a positive feedback between exposed-rock extent, BIA formation, melting and ice-sheet thinning. This feedback relies on drainage moving water long distances from areas near exposed rock, across the grounding line onto and across ice shelves - a process we observe, but had previously thought to be unlikely in Antarctica. This work highlights previously-overlooked processes, not captured by current regional-scale models, which may accelerate the retreat of the Antarctic Ice Sheet.

Contributions to Crustal Mechanics on Europa from Subterranean Ocean Vibrations

NASA Astrophysics Data System (ADS)

Hayes, Robert

2016-03-01

The recent discovery of subduction zones on Europa demonstrated a significant step forward in understanding the moon's surface mechanics. This work promotes the additional consideration that the surface mechanics have contributions from small relative pressure differentials in the subsurface ocean that create cracks in the surface which are then filled, sealed and healed. Crack formation can be small, as interior pressure can relatively easily breach the surface crust, generating cracks followed by common fracture formation backfilled with frozen liquid. This process will slowly increase the overall surface area of the moon with each sealed crack and fracture increasing the total surface area. This creeping growth of surface area monotonically decreases subsurface pressure which can eventually catastrophically subduct large areas of surface and so is consistent with current knowledge of observational topology on Europa. This tendency is attributed to a relatively lower energy threshold to crack the surface from interior overpressures, but a higher energy threshold to crush the spherical surface due to subsurface underpressures. Proposed mechanisms for pressure differentials include tidal forces whose Fourier components build up the resonant oscillatory modes of the subsurface ocean creating periodic under and overpressure events below the crust. This mechanism provides a means to continually reform the surface of the moon over short geological time scales. This work supported in part by federal Grant NRC-HQ-84-14-G-0059.

Linking playa surface dust emission potential to feedbacks between surface moisture and salt crust expansion through high resolution terrestrial laser scanning measurements

NASA Astrophysics Data System (ADS)

Nield, J. M.; King, J.; Wiggs, G.

2012-12-01

The dust emissivity of salt pans (or playas) can be significant but is controlled by interactions between wind erosivity, surface moisture, salt chemistry and crust morphology. These surface properties influence the aeolian transport threshold and can be highly variable over both short temporal and spatial scales. In the past, field studies have been hampered by practical difficulties in accurately measuring properties controlling sediment availability at the surface in high resolution. Studies typically therefore, have investigated large scale monthly or seasonal change using remote sensing and assume a homogeneous surface when predicting dust emissivity. Here we present the first high resolution measurements (sub-cm) of salt crust expansion related to changes in diurnal moisture over daily and weekly time periods using terrestrial laser scanning (TLS, ground-based LiDAR) on Sua Pan, Botswana. The TLS measures both elevation and relative surface moisture change simultaneously, without disturbing the surface. Measurement sequences enable the variability in aeolian sediment availability to be quantified along with temporal feedbacks associated with crust degradation. On crusts with well-developed polygon ridges (high aerodynamic and surface roughness), daily surface expansion was greater than 30mm. The greatest surface change occurred overnight on the upper, exposed sections of the ridges, particularly when surface temperatures dropping below 10°C. These areas also experienced the greatest moisture variation and became increasingly moist overnight in response to an increase in relative humidity. In contrast, during daylight hours, the ridge areas were drier than the lower lying inter-ridge areas. Positive feedbacks between surface topography and moisture reinforced the maximum diurnal moisture variation at ridge peaks, encouraging crust thrusting due to overnight salt hydration, further enhancing the surface, and therefore, aerodynamic roughness. These feedbacks between surface roughness and moisture have implications for dust emissivity because crust expansion increases fluff production which is one of the main dust source materials. Further, increased roughness can locally increase wind erosivity and the potential evaporation of ridge areas. Crust thrusting also weakens the ridge peaks, developing cracked surfaces and exposing the sediment supply source below. These fast acting processes can have a major influence on wind erosion variability and dust emissivity from key dust source regions.; a-d) Elevation change overnight. e-f) Elevation change over 6 days.

Geochemistry of surface water in alpine catchments in central Colorado, USA: Resolving host-rock effects at different spatial scales

USGS Publications Warehouse

Wanty, R.B.; Verplanck, P.L.; San, Juan C.A.; Church, S.E.; Schmidt, T.S.; Fey, D.L.; deWitt, E.H.; Klein, T.L.

2009-01-01

The US Geological Survey is conducting a study of surface-water quality in the Rocky Mountains of central Colorado, an area of approximately 55,000 km2. Using new and existing geologic maps, the more than 200 rock formations represented in the area were arranged into 17 groups based on lithologic similarity. The dominant regional geologic feature affecting water quality in central Colorado is the Colorado mineral belt (CMB), a NE-trending zone hosting many polymetallic vein or replacement deposits, and porphyry Mo deposits, many of which have been mined historically. The influence of the CMB is seen in lower surface-water pH (<5), and higher concentrations of SO42 - (>100 mg/L) and chalcophile metals such as Cu (>10 ??g/L), Zn (>100 ??g/L), and Cd (>1 ??g/L) relative to surface water outside the CMB. Not all streams within the CMB have been affected by mineralization, as there are numerous catchments within the CMB that have no mineralization or alteration exposed at the surface. At the regional-scale, and away from sites affected by mineralization, hydrothermal alteration, or mining, the effects of lithology on water quality can be distinguished using geochemical reaction modeling and principal components analysis. At local scales (100 s of km2), effects of individual rock units on water chemistry are subtle but discernible, as shown by variations in concentrations of major lithophile elements or ratios between them. These results demonstrate the usefulness of regional geochemical sampling of surface waters and process-based interpretations incorporating geologic and geochemical understanding to establish geochemical baselines.

The influence of the fault zone width on land surface vibrations after the high-energy tremor in the "Rydułtowy-Anna" hard coal mine

NASA Astrophysics Data System (ADS)

Pilecka, Elżbieta; Szwarkowski, Dariusz

2018-04-01

In the article, a numerical analysis of the impact of the width of the fault zone on land surface tremors on the area of the "Rydułtowy - Anna" hard coal mine was performed. The analysis covered the dynamic impact of the actual seismic wave after the high-energy tremor of 7 June 2013. Vibrations on the land surface are a measure of the mining damage risk. It is particularly the horizontal components of land vibrations that are dangerous to buildings which is reflected in the Mining Scales of Intensity (GSI) of vibrations. The run of a seismic wave in the rock mass from the hypocenter to the area's surface depends on the lithology of the area and the presence of fault zones. The rock mass network cut by faults of various widths influences the amplitude of tremor reaching the area's surface. The analysis of the impact of the width of the fault zone was done for three alternatives.

Surficial Geologic Map of the Ashby-Lowell-Sterling-Billerica 11-Quadrangle Area in Northeast-Central Massachusetts

USGS Publications Warehouse

Stone, Byron D.; Stone, Janet R.

2007-01-01

The surficial geologic map shows the distribution of nonlithified earth materials at land surface in an area of eleven 7.5-minute quadrangles (total 505 mi2) in northeast-central Massachusetts. The geologic map differentiates surficial materials of Quaternary age on the basis of their lithologic characteristics (such as grain size and sedimentary structures), constructional geomorphic features, stratigraphic relationships, and age. Surficial earth materials significantly affect human use of the land, and an accurate description of their distribution is particularly important for water resources, construction aggregate resources, earth-surface hazards assessments, and land-use decisions. This compilation of surficial geologic materials is an interim product that defines the areas of exposed bedrock, and the boundaries between glacial till, glacial stratified deposits, and overlying postglacial deposits. This work is part of a comprehensive study to produce a statewide digital map of the surficial geology at a 1:24,000-scale level of accuracy. This report includes explanatory text (PDF), a regional map at 1:50,000 scale (PDF), quadrangle maps at 1:24,000 scale (PDF files), GIS data layers (ArcGIS shapefiles), metadata for the GIS layers, scanned topographic base maps (TIF), and a readme.txt file.

Surficial Geologic Map of the Salem Depot-Newburyport East-Wilmington-Rockport 16-Quadrangle Area in Northeast Massachusetts

USGS Publications Warehouse

Stone, Byron D.; Stone, Janet Radway; DiGiacomo-Cohen, Mary L.

2006-01-01

The surficial geologic map shows the distribution of nonlithified earth materials at land surface in an area of 16 7.5-minute quadrangles (total 658 mi2) in northeast Massachusetts. The geologic map differentiates surficial materials of Quaternary age on the basis of their lithologic characteristics (grain size, sedimentary structures, mineral and rock-particle composition), constructional geomorphic features, stratigraphic relationships, and age. Surficial earth materials significantly affect human use of the land, and an accurate description of their distribution is particularly important for water resources, construction aggregate resources, earth-surface hazards assessments, and land-use decisions. This compilation of surficial geologic materials is an interim product that defines the areas of exposed bedrock, and the boundaries between glacial till, glacial stratified deposits, and overlying postglacial deposits. This work is part of a comprehensive study to produce a statewide digital map of the surficial geology at a 1:24,000-scale level of accuracy. This report includes explanatory text (PDF), a regional map at 1:50,000 scale (PDF), quadrangle maps at 1:24,000 scale (PDF files), GIS data layers (ArcGIS shapefiles), metadata for the GIS layers, scanned topographic base maps (TIF), and a readme.txt file.

Quantifying the Significance of Heterogeneity in Supraglacial Reflectance Characteristics for Meltwater Production in Southwest Greenland

NASA Astrophysics Data System (ADS)

Irvine-Fynn, T. D.; Bunting, P.; Cook, J.; Hardy, A. J.; Hodson, A. J.; Holt, T.; Hubbard, A.; Naegeli, K.; Nilsson, J.; Ryan, J.; Roberts, O.; Tedstone, A.; Tranter, M.; Williamson, C.

2017-12-01

The seasonal melt on the southwestern margin of the Greenland Ice Sheet has been enhanced due to processes affecting the ablation area's ice surface reflectance (albedo). Recent trends in surface reflectance in the region suggest a decline potentially linked to an albedo-feedback associated with regional climate warming, emergence of organic and mineral particulates, and expansion of melt area. However, the heterogeneity of reflectance over bare ice areas in space and time has remained relatively poorly characterised. Numerous surface mass balance models utilise albedo products derived from remote sensing platforms with coarse scale resolution. Such products provide reasonable albedo estimates, but quantification of local variability in reflectance remains lacking. Consequently, there is a need to better define the distribution and representativeness of ice surface reflectance at and below the scale of satellite sensor pixel footprints to facilitate examination of albedo parameterisations. Here, we present reflectance data repeatedly collected in SW Greenland during the 2016 summer melt season over a 0.0625 km2 area proximate to the IMAU K-transect site S6 (67°04.5'N, 49°21.0'W). The Moderate Resolution Imaging Spectrometer (MODIS) albedo product MOD10A1(c6) for the study site was compared to reflectance data from Sentinel-2, centimetre resolution calibrated 12Mpix optical imagery collected using an Unmanned Aerial Vehicle (UAV) flown at a height of 70 m above the ice surface, and ground-based reflectance survey data acquired using a StellarNet Red-Dwarf/Blue-Wave visible-infrared dual system (250-1700nm) at 30 sites distributed over the area of interest. Our data highlight variability in the spatial distribution of ice surface reflectance characteristics over time. Specifically, data demonstrate marked changes in the distribution of reflectance values, despite maintaining a broadly equitable mean and median during July and August. The influence of the varied surface heterogeneity is explored further using surface energy balance modelling to quantify the impact of such changes on melt production. The findings determine the necessity to account for local variability underlying the pixel-averaged values retrieved from remote sensing platforms such as MODIS.

Effect of elongation in divertor tokamaks

NASA Astrophysics Data System (ADS)

Jones, Morgin; Ali, Halima; Punjabi, Alkesh

2008-04-01

Method of maps developed by Punjabi and Boozer [A. Punjabi, A. Verma, and A. Boozer, Phys.Rev. Lett. 69, 3322 (1992)] is used to calculate the effects of elongation on stochastic layer and magnetic footprint in divertor tokamaks. The parameters in the map are chosen such that the poloidal magnetic flux χSEP inside the ideal separatrix, the amplitude δ of magnetic perturbation, and the height H of the ideal separatrix surface are held fixed. The safety factor q for the flux surfaces that are nonchaotic as a function of normalized distance d from the O-point to the X-point is also held approximately constant. Under these conditions, the width W of the ideal separatrix surface in the midplane through the O-point is varied. The relative width w of stochastic layer near the X-point and the area A of magnetic footprint are then calculated. We find that the normalized width w of stochastic layer scales as W-7, and the area A of magnetic footprint on collector plate scales as W-10.

The spectroscopy and chemical dynamics of microparticles explored using an ultrasonic trap.

PubMed

Mason, N J; Drage, E A; Webb, S M; Dawes, A; McPheat, R; Hayes, G

2008-01-01

Microsized particles play an important role in many diverse areas of science and technology, for example, surface reactions of micron-sized particles play a key role in astrochemistry, plasma reactors and atmospheric chemistry. To date much of our knowledge of such surface chemistry is derived from 'traditional' surface science-based research. However, the large surface area and morphology of surface material commonly used in such surface science techniques may not necessarily mimic that on the surface of micron/nano scale particles. Hence, a new generation of experiments in which the spectroscopy (e.g., albedo) and chemical reactivity of micron-sized particles can be studied directly must be developed. One, as yet underexploited, non-invasive technique is the use of ultrasonic levitation. In this article, we describe the operation of an 'ultrasonic trap' to store and study the physical and chemical properties of microparticles.

[Nanotechnology--possibilities and hazards].

PubMed

Snopczyński, Tomasz; Góralczyk, Katarzyna; Czaja, Katarzyna; Struciński, Paweł; Hernik, Agnieszka; Korcz, Wojciech; Ludwicki, Jan K

2009-01-01

Nanoparticles are the objects with at least one demension smaller than 100 nm. Nanoparticles exist in nature or can be produced by human activities, intentionally or unintentionally. Nanotechnology is an emerging science involving manipulation of matter at nanometer scale. Nanoparticles find numerous applications in many fields, starting with electronics, throught medicine, cosmetology, and ending with automotive industry and construction industry. Depending on the use of nanoparticles, the routes of exposure may be inhalation, dermal, oral or parenteral. Nanoparticles have a greater active surface area per unit mass than larger particles. Together with an increase of surface area, toxicity and potential health effects may also increase. Toxicity of nanoparticles depend on many factors, for example: size, shape, chemical composition, solubility, surface area and surface charge. Risk assessment related to human health, should be integrated at all stages of the life cycle of the nanotechnology, starting at the point of conception and including research and development, manufacturing, distribution, use and disposal or recycling.

Analysis of small scale turbulent structures and the effect of spatial scales on gas transfer

NASA Astrophysics Data System (ADS)

Schnieders, Jana; Garbe, Christoph

2014-05-01

The exchange of gases through the air-sea interface strongly depends on environmental conditions such as wind stress and waves which in turn generate near surface turbulence. Near surface turbulence is a main driver of surface divergence which has been shown to cause highly variable transfer rates on relatively small spatial scales. Due to the cool skin of the ocean, heat can be used as a tracer to detect areas of surface convergence and thus gather information about size and intensity of a turbulent process. We use infrared imagery to visualize near surface aqueous turbulence and determine the impact of turbulent scales on exchange rates. Through the high temporal and spatial resolution of these types of measurements spatial scales as well as surface dynamics can be captured. The surface heat pattern is formed by distinct structures on two scales - small-scale short lived structures termed fish scales and larger scale cold streaks that are consistent with the footprints of Langmuir Circulations. There are two key characteristics of the observed surface heat patterns: 1. The surface heat patterns show characteristic features of scales. 2. The structure of these patterns change with increasing wind stress and surface conditions. In [2] turbulent cell sizes have been shown to systematically decrease with increasing wind speed until a saturation at u* = 0.7 cm/s is reached. Results suggest a saturation in the tangential stress. Similar behaviour has been observed by [1] for gas transfer measurements at higher wind speeds. In this contribution a new model to estimate the heat flux is applied which is based on the measured turbulent cell size und surface velocities. This approach allows the direct comparison of the net effect on heat flux of eddies of different sizes and a comparison to gas transfer measurements. Linking transport models with thermographic measurements, transfer velocities can be computed. In this contribution, we will quantify the effect of small scale processes on interfacial transport and relate it to gas transfer. References [1] T. G. Bell, W. De Bruyn, S. D. Miller, B. Ward, K. Christensen, and E. S. Saltzman. Air-sea dimethylsulfide (DMS) gas transfer in the North Atlantic: evidence for limited interfacial gas exchange at high wind speed. Atmos. Chem. Phys. , 13:11073-11087, 2013. [2] J Schnieders, C. S. Garbe, W.L. Peirson, and C. J. Zappa. Analyzing the footprints of near surface aqueous turbulence - an image processing based approach. Journal of Geophysical Research-Oceans, 2013.

Automated mapping of impervious surfaces in urban and suburban areas: Linear spectral unmixing of high spatial resolution imagery

NASA Astrophysics Data System (ADS)

Yang, Jian; He, Yuhong

2017-02-01

Quantifying impervious surfaces in urban and suburban areas is a key step toward a sustainable urban planning and management strategy. With the availability of fine-scale remote sensing imagery, automated mapping of impervious surfaces has attracted growing attention. However, the vast majority of existing studies have selected pixel-based and object-based methods for impervious surface mapping, with few adopting sub-pixel analysis of high spatial resolution imagery. This research makes use of a vegetation-bright impervious-dark impervious linear spectral mixture model to characterize urban and suburban surface components. A WorldView-3 image acquired on May 9th, 2015 is analyzed for its potential in automated unmixing of meaningful surface materials for two urban subsets and one suburban subset in Toronto, ON, Canada. Given the wide distribution of shadows in urban areas, the linear spectral unmixing is implemented in non-shadowed and shadowed areas separately for the two urban subsets. The results indicate that the accuracy of impervious surface mapping in suburban areas reaches up to 86.99%, much higher than the accuracies in urban areas (80.03% and 79.67%). Despite its merits in mapping accuracy and automation, the application of our proposed vegetation-bright impervious-dark impervious model to map impervious surfaces is limited due to the absence of soil component. To further extend the operational transferability of our proposed method, especially for the areas where plenty of bare soils exist during urbanization or reclamation, it is still of great necessity to mask out bare soils by automated classification prior to the implementation of linear spectral unmixing.

Evaluation of Hydrogel Technologies for the Decontamination ...

EPA Pesticide Factsheets

Report This current research effort was developed to evaluate intermediate level (between bench-scale and large-scale or wide-area implementation) decontamination procedures, materials, technologies, and techniques used to remove radioactive material from different surfaces. In the event of such an incident, application of this technology would primarily be intended for decontamination of high-value buildings, important infrastructure, and landmarks.

Determination of Large-Scale Cloud Ice Water Concentration by Combining Surface Radar and Satellite Data in Support of ARM SCM Activities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Guosheng

2013-03-15

Single-column modeling (SCM) is one of the key elements of Atmospheric Radiation Measurement (ARM) research initiatives for the development and testing of various physical parameterizations to be used in general circulation models (GCMs). The data required for use with an SCM include observed vertical profiles of temperature, water vapor, and condensed water, as well as the large-scale vertical motion and tendencies of temperature, water vapor, and condensed water due to horizontal advection. Surface-based measurements operated at ARM sites and upper-air sounding networks supply most of the required variables for model inputs, but do not provide the horizontal advection term ofmore » condensed water. Since surface cloud radar and microwave radiometer observations at ARM sites are single-point measurements, they can provide the amount of condensed water at the location of observation sites, but not a horizontal distribution of condensed water contents. Consequently, observational data for the large-scale advection tendencies of condensed water have not been available to the ARM cloud modeling community based on surface observations alone. This lack of advection data of water condensate could cause large uncertainties in SCM simulations. Additionally, to evaluate GCMs cloud physical parameterization, we need to compare GCM results with observed cloud water amounts over a scale that is large enough to be comparable to what a GCM grid represents. To this end, the point-measurements at ARM surface sites are again not adequate. Therefore, cloud water observations over a large area are needed. The main goal of this project is to retrieve ice water contents over an area of 10 x 10 deg. surrounding the ARM sites by combining surface and satellite observations. Built on the progress made during previous ARM research, we have conducted the retrievals of 3-dimensional ice water content by combining surface radar/radiometer and satellite measurements, and have produced 3-D cloud ice water contents in support of cloud modeling activities. The approach of the study is to expand a (surface) point measurement to an (satellite) area measurement. That is, the study takes the advantage of the high quality cloud measurements (particularly cloud radar and microwave radiometer measurements) at the point of the ARM sites. We use the cloud ice water characteristics derived from the point measurement to guide/constrain a satellite retrieval algorithm, then use the satellite algorithm to derive the 3-D cloud ice water distributions within an 10° (latitude) x 10° (longitude) area. During the research period, we have developed, validated and improved our cloud ice water retrievals, and have produced and archived at ARM website as a PI-product of the 3-D cloud ice water contents using combined satellite high-frequency microwave and surface radar observations for SGP March 2000 IOP and TWP-ICE 2006 IOP over 10 deg. x 10 deg. area centered at ARM SGP central facility and Darwin sites. We have also worked on validation of the 3-D ice water product by CloudSat data, synergy with visible/infrared cloud ice water retrievals for better results at low ice water conditions, and created a long-term (several years) of ice water climatology in 10 x 10 deg. area of ARM SGP and TWP sites and then compared it with GCMs.« less

InterProSurf: a web server for predicting interacting sites on protein surfaces

PubMed Central

Negi, Surendra S.; Schein, Catherine H.; Oezguen, Numan; Power, Trevor D.; Braun, Werner

2009-01-01

Summary A new web server, InterProSurf, predicts interacting amino acid residues in proteins that are most likely to interact with other proteins, given the 3D structures of subunits of a protein complex. The prediction method is based on solvent accessible surface area of residues in the isolated subunits, a propensity scale for interface residues and a clustering algorithm to identify surface regions with residues of high interface propensities. Here we illustrate the application of InterProSurf to determine which areas of Bacillus anthracis toxins and measles virus hemagglutinin protein interact with their respective cell surface receptors. The computationally predicted regions overlap with those regions previously identified as interface regions by sequence analysis and mutagenesis experiments. PMID:17933856

Dynamic Melting of Freezing Droplets on Ultraslippery Superhydrophobic Surfaces.

PubMed

Chu, Fuqiang; Wu, Xiaomin; Wang, Lingli

2017-03-08

Condensed droplet freezing and freezing droplet melting phenomena on the prepared ultraslippery superhydrophobic surface were observed and discussed in this study. Although the freezing delay performance of the surface is common, the melting of the freezing droplets on the surface is quite interesting. Three self-propelled movements of the melting droplets (ice- water mixture) were found including the droplet rotating, the droplet jumping, and the droplet sliding. The melting droplet rotating, which means that the melting droplet rotates spontaneously on the superhydrophobic surface like a spinning top, is first reported in this study and may have some potential applications in various engineering fields. The melting droplet jumping and sliding are similar to those occurring during condensation but have larger size scale and motion scale, as the melting droplets have extra-large specific surface area with much more surface energy available. These self-propelled movements make all the melting droplets on the superhydrophobic surface dynamic, easily removed, which may be promising for the anti-icing/frosting applications.

Arecibo radar observations of Mars surface characteristics in the Northern Hemisphere

NASA Technical Reports Server (NTRS)

Simpson, R. A.; Tyler, G. L.; Campbell, D. B.

1978-01-01

Mars surface characteristics at and near the Viking Chryse and Tritonis Lacus landing areas were determined by radio scatter using the 12.6-cm radar at the Arecibo Observatory during 1975-76. Interpretation of each power spectrum suggests rms surface tilts of 4 deg at the final A1WNW (47.9 deg W, 22.5 deg N) site, 5 deg near the original A1 site, and 6 deg between the two. At the back-up site (A2) surface-roughness estimates were about 4 deg. Striking changes in surface texture have been found near the eastern bases of Tharsis Montes and Albor Tholus, each volcanic feature marking the western boundary of very smooth surface units. The roughness sensed at 1- to 100-m scales by radar appears to be relatively independent of the surface units defined at large scale lengths by photogeologists. Radar properties thus provide an additional means by which planetary surfaces may be characterized.

Evaluation of Existing Image Matching Methods for Deriving Glacier Surface Displacements Globally from Optical Satellite Imagery

NASA Astrophysics Data System (ADS)

Heid, T.; Kääb, A.

2011-12-01

Automatic matching of images from two different times is a method that is often used to derive glacier surface velocity. Nearly global repeat coverage of the Earth's surface by optical satellite sensors now opens the possibility for global-scale mapping and monitoring of glacier flow with a number of applications in, for example, glacier physics, glacier-related climate change and impact assessment, and glacier hazard management. The purpose of this study is to compare and evaluate different existing image matching methods for glacier flow determination over large scales. The study compares six different matching methods: normalized cross-correlation (NCC), the phase correlation algorithm used in the COSI-Corr software, and four other Fourier methods with different normalizations. We compare the methods over five regions of the world with different representative glacier characteristics: Karakoram, the European Alps, Alaska, Pine Island (Antarctica) and southwest Greenland. Landsat images are chosen for matching because they expand back to 1972, they cover large areas, and at the same time their spatial resolution is as good as 15 m for images after 1999 (ETM+ pan). Cross-correlation on orientation images (CCF-O) outperforms the three similar Fourier methods, both in areas with high and low visual contrast. NCC experiences problems in areas with low visual contrast, areas with thin clouds or changing snow conditions between the images. CCF-O has problems on narrow outlet glaciers where small window sizes (about 16 pixels by 16 pixels or smaller) are needed, and it also obtains fewer correct matches than COSI-Corr in areas with low visual contrast. COSI-Corr has problems on narrow outlet glaciers and it obtains fewer correct matches compared to CCF-O when thin clouds cover the surface, or if one of the images contains snow dunes. In total, we consider CCF-O and COSI-Corr to be the two most robust matching methods for global-scale mapping and monitoring of glacier velocities. If combining CCF-O with locally adaptive template sizes and by filtering the matching results automatically by comparing the displacement matrix to its low pass filtered version, the matching process can be automated to a large degree. This allows the derivation of glacier velocities with minimal (but not without!) user interaction and hence also opens up the possibility of global-scale mapping and monitoring of glacier flow.

Aquatic adaptations in the nose of carnivorans: evidence from the turbinates

PubMed Central

Van Valkenburgh, Blaire; Curtis, Abigail; Samuels, Joshua X; Bird, Deborah; Fulkerson, Brian; Meachen-Samuels, Julie; Slater, Graham J

2011-01-01

Inside the mammalian nose lies a labyrinth of bony plates covered in epithelium collectively known as turbinates. Respiratory turbinates lie anteriorly and aid in heat and water conservation, while more posterior olfactory turbinates function in olfaction. Previous observations on a few carnivorans revealed that aquatic species have relatively large, complex respiratory turbinates and greatly reduced olfactory turbinates compared with terrestrial species. Body heat is lost more quickly in water than air and increased respiratory surface area likely evolved to minimize heat loss. At the same time, olfactory surface area probably diminished due to a decreased reliance on olfaction when foraging under water. To explore how widespread these adaptations are, we documented scaling of respiratory and olfactory turbinate surface area with body size in a variety of terrestrial, freshwater, and marine carnivorans, including pinnipeds, mustelids, ursids, and procyonids. Surface areas were estimated from high-resolution CT scans of dry skulls, a novel approach that enabled a greater sampling of taxa than is practical with fresh heads. Total turbinate, respiratory, and olfactory surface areas correlate well with body size (r2 ≥ 0.7), and are relatively smaller in larger species. Relative to body mass or skull length, aquatic species have significantly less olfactory surface area than terrestrial species. Furthermore, the ratio of olfactory to respiratory surface area is associated with habitat. Using phylogenetic comparative methods, we found strong support for convergence on 1 : 3 proportions in aquatic taxa and near the inverse in terrestrial taxa, indicating that aquatic mustelids and pinnipeds independently acquired similar proportions of olfactory to respiratory turbinates. Constraints on turbinate surface area in the nasal chamber may result in a trade-off between respiratory and olfactory function in aquatic mammals. PMID:21198587

Land Capability Potential Index (LCPI) for the Lower Missouri River Valley

USGS Publications Warehouse

Jacobson, Robert B.; Chojnacki, Kimberly A.; Reuter, Joanna M.

2007-01-01

The Land Capability Potential Index (LCPI) was developed to serve as a relatively coarse-scale index to delineate broad land capability classes in the valley of the Lower Missouri River. The index integrates fundamental factors that determine suitability of land for various uses, and may provide a useful mechanism to guide land-management decisions. The LCPI was constructed from integration of hydrology, hydraulics, land-surface elevations, and soil permeability (or saturated hydraulic conductivity) datasets for an area of the Lower Missouri River, river miles 423–670. The LCPI estimates relative wetness based on intersecting water-surface elevations, interpolated from measurements or calculated from hydraulic models, with a high-resolution land-surface elevation dataset. The potential for wet areas to retain or drain water is assessed using soil-drainage classes that are estimated from saturated hydraulic conductivity of surface soils. Terrain mapping that delineates areas with convex, concave, and flat parts of the landscape provides another means to assess tendency of landscape patches to retain surface water.

Confocal laser scanning microscopy and area-scale analysis used to quantify enamel surface textural changes from citric acid demineralization and salivary remineralization in vitro.

PubMed

Austin, R S; Giusca, C L; Macaulay, G; Moazzez, R; Bartlett, D W

2016-02-01

This paper investigates the application of confocal laser scanning microscopy to determine the effect of acid-mediated erosive enamel wear on the micro-texture of polished human enamel in vitro. Twenty polished enamel samples were prepared and subjected to a citric acid erosion and pooled human saliva remineralization model. Enamel surface microhardness was measured using a Knoop hardness tester, which confirmed that an early enamel erosion lesion was formed which was then subsequently completely remineralized. A confocal laser scanning microscope was used to capture high-resolution images of the enamel surfaces undergoing demineralization and remineralization. Area-scale analysis was used to identify the optimal feature size following which the surface texture was determined using the 3D (areal) texture parameter Sa. The Sa successfully characterized the enamel erosion and remineralization for the polished enamel samples (P<0.001). Areal surface texture characterization of the surface events occurring during enamel demineralization and remineralization requires optical imaging instrumentation with lateral resolution <2.5 μm, applied in combination with appropriate filtering in order to remove unwanted waviness and roughness. These techniques will facilitate the development of novel methods for measuring early enamel erosion lesions in natural enamel surfaces in vivo. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Modeling the Effects of Irrigation on Land Surface Fluxes and States over the Conterminous United States: Sensitivity to Input Data and Model Parameters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leng, Guoyong; Huang, Maoyi; Tang, Qiuhong

2013-09-16

Previous studies on irrigation impacts on land surface fluxes/states were mainly conducted as sensitivity experiments, with limited analysis of uncertainties from the input data and model irrigation schemes used. In this study, we calibrated and evaluated the performance of irrigation water use simulated by the Community Land Model version 4 (CLM4) against observations from agriculture census. We investigated the impacts of irrigation on land surface fluxes and states over the conterminous United States (CONUS) and explored possible directions of improvement. Specifically, we found large uncertainty in the irrigation area data from two widely used sources and CLM4 tended to producemore » unrealistically large temporal variations of irrigation demand for applications at the water resources region scale over CONUS. At seasonal to interannual time scales, the effects of irrigation on surface energy partitioning appeared to be large and persistent, and more pronounced in dry than wet years. Even with model calibration to yield overall good agreement with the irrigation amounts from the National Agricultural Statistics Service (NASS), differences between the two irrigation area datasets still dominate the differences in the interannual variability of land surface response to irrigation. Our results suggest that irrigation amount simulated by CLM4 can be improved by (1) calibrating model parameter values to account for regional differences in irrigation demand and (2) accurate representation of the spatial distribution and intensity of irrigated areas.« less

[Characteristics of water and heat fluxes and its footprint climatology on farmland in low hilly region of red soil].

PubMed

Li, Yang; Jing, Yuan Shu; Qin, Ben Ben

2017-01-01

The analysis of the characteristics and footprint climatology of farmland water and heat fluxes has great significance to strengthen regional climate resource management and improve the hydrothermal resource utilization in the region of red soil. Based on quality controlled data from large aperture scintillometer and automatic meteorological station in hilly region of red soil, this paper analyzed in detail the characteristics of farmland water and heat fluxes at different temporal scales and the corresponding source area distribution of flux measurement in the non-rainy season and crop growth period in hilly region of red soil. The results showed that the diurnal variation of water and heat fluxes showed a unimodal trend, but compared with the sunny day, the diurnal variation curves fluctuated more complicatedly on cloudy day. In the whole, either ten-day periods or month scale, the water and heat fluxes were greater in August than in September, while the net radiation flux was more distributed to latent heat exchange. The proportion of net radiation to latent heat flux decreased in September compared to August, but the sensible heat flux was vice versa. With combined effects of weather conditions (particularly wind), stability, and surface condition, the source areas of flux measurement at different temporal scales showed different distribution characteristics. Combined with the underlying surface crops, the source areas at different temporal scales also had different contribution sources.

Synthesis of rose-like boron nitride particles with a high specific surface area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Hongming; Huang, Xiaoxiao; Wen, Guangwu, E-mail: wgw@hitwh.edu.cn

2010-08-15

Novel rose-like BN nanostructures were synthesized on a large scale via a two-step procedure. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectrometer and nitrogen porosimetry. The results show that the obtained rose-like nanostructures are composed of a large amount of h-BN crystalline flakes and have a surface area of 90.31 m{sup 2}/g. A mechanism was proposed to explain the formation process of the rose-like BN nanostructures.

Fluid Lensing and Applications to Remote Sensing of Aquatic Environments

NASA Technical Reports Server (NTRS)

Chirayath, Ved

2017-01-01

The use of fluid lensing technology on UAVs is presented as a novel means for 3D imaging of aquatic ecosystems from above the water's surface at the centimeter scale. Preliminary results are presented from airborne fluid lensing campaigns conducted over the coral reefs of Ofu Island, American Samoa (2013) and the stromatolite reefs of Shark Bay, Western Australia (2014), covering a combined area of 15km2. These reef ecosystems were revealed with centimetre-scale 2D resolution, and an accompanying 3D bathymetry model was derived using fluid lensing, Structure from Motion and UAV position data. Data products were validated from in-situ survey methods including underwater calibration targets, depth measurements and millimetre-scale high-dynamic range gigapixel photogrammetry. Fluid lensing is an experimental technology that uses water transmitting wavelengths to passively image underwater objects at high-resolution by exploiting time-varying optical lensing events caused by surface waves. Fluid lensing data are captured from low-altitude, cost-effective electric UAVs to achieve multispectral imagery and bathymetry models at the centimetre scale over regional areas. As a passive system, fluid lensing is presently limited by signal-to-noise ratio and water column inherent optical properties to approximately 10 m depth over visible wavelengths in clear waters. The datasets derived from fluid lensing present the first centimetre-scale images of a reef acquired from above the ocean surface, without wave distortion. The 3D multispectral data distinguish coral, fish and invertebrates in American Samoa, and reveal previously undocumented, morphologically distinct, stromatolite structures in Shark Bay. These findings suggest fluid lensing and multirotor electric drones represent a promising advance in the remote sensing of aquatic environments at the centimetre scale, or 'reef scale' relevant to the conservation of reef ecosystems. Pending further development and validation of fluid lensing methods, these technologies present a solution for large-scale 3D surveys of shallow aquatic habitats with centimetre-scale spatial resolution and hourly temporal sampling.

From Shoestring Rills to Dendritic River Networks: Documenting the Evolution of River Basins Towards Geometric Similarity Through Divide Migration, Stream Capture and Lateral Branching

NASA Astrophysics Data System (ADS)

Beeson, H. W.; McCoy, S. W.; Willett, S.

2016-12-01

Erosional river networks dissect much of Earth's surface into drainage basins. Global scaling laws such as Hack's Law suggest that river basins trend toward a particular scale-invariant shape. While erosional instabilities arising from competition between advective and diffusive processes can explain why headwaters branch, the erosional mechanics linking larger scale network branching with evolution towards a characteristic river basin shape remain poorly constrained. We map river steepness and a proxy for the steady-state elevation of river networks, χ, in simulated and real landscapes with a large range in spatial scale (102 -106 m) but with similar inclined, planar surfaces at the time of incipient network formation. We document that the evolution from narrow rill-like networks to dendritic, leaf-shaped river basins follows from drainage area differences between catchments. These serve as instabilities that grow, leading to divide migration, stream capture, lateral branching and network reorganization. As Horton hypothesized, incipient networks formed down gradient on an inclined, planar surface have an unequal distribution of drainage area and nonuniformity in response times such that larger basins erode more rapidly and branch laterally via capture of adjacent streams with lower erosion rates. Positive feedback owing to increase in drainage area furthers the process of branching at the expense of neighboring rivers. We show that drainage area exchange and the degree of network reorganization has a significant effect on river steepness in the Dragon's Back Pressure Ridge, CA, the Sierra Nevada, CA, and the Rocky Mountain High Plains, USA. Similarly, metrics of basin shape reveal that basins are evolving from narrow basins towards more common leaf shapes. Our results suggest that divide migration and stream capture driven by erosional disequilibrium could be fundamental processes by which river basins reach their characteristic geometry and dendritic form.

Extended-range high-resolution dynamical downscaling over a continental-scale spatial domain with atmospheric and surface nudging

NASA Astrophysics Data System (ADS)

Husain, S. Z.; Separovic, L.; Yu, W.; Fernig, D.

2014-12-01

Extended-range high-resolution mesoscale simulations with limited-area atmospheric models when applied to downscale regional analysis fields over large spatial domains can provide valuable information for many applications including the weather-dependent renewable energy industry. Long-term simulations over a continental-scale spatial domain, however, require mechanisms to control the large-scale deviations in the high-resolution simulated fields from the coarse-resolution driving fields. As enforcement of the lateral boundary conditions is insufficient to restrict such deviations, large scales in the simulated high-resolution meteorological fields are therefore spectrally nudged toward the driving fields. Different spectral nudging approaches, including the appropriate nudging length scales as well as the vertical profiles and temporal relaxations for nudging, have been investigated to propose an optimal nudging strategy. Impacts of time-varying nudging and generation of hourly analysis estimates are explored to circumvent problems arising from the coarse temporal resolution of the regional analysis fields. Although controlling the evolution of the atmospheric large scales generally improves the outputs of high-resolution mesoscale simulations within the surface layer, the prognostically evolving surface fields can nevertheless deviate from their expected values leading to significant inaccuracies in the predicted surface layer meteorology. A forcing strategy based on grid nudging of the different surface fields, including surface temperature, soil moisture, and snow conditions, toward their expected values obtained from a high-resolution offline surface scheme is therefore proposed to limit any considerable deviation. Finally, wind speed and temperature at wind turbine hub height predicted by different spectrally nudged extended-range simulations are compared against observations to demonstrate possible improvements achievable using higher spatiotemporal resolution.

Green Infrastructure and Watershed-Scale Hydrology in a Mixed Land Cover System

NASA Astrophysics Data System (ADS)

Hoghooghi, N.; Golden, H. E.; Bledsoe, B. P.

2017-12-01

Urbanization results in replacement of pervious areas (e.g., vegetation, topsoil) with impervious surfaces such as roads, roofs, and parking lots, which cause reductions in interception, evapotranspiration, and infiltration, and increases in surface runoff (overland flow) and pollutant loads and concentrations. Research on the effectiveness of different Green Infrastructure (GI), or Low Impact Development (LID), practices to reduce these negative impacts on stream flow and water quality has been mostly focused at the local scale (e.g., plots, small catchments). However, limited research has considered the broader-scale effects of LID, such as how LID practices influence water quantity, nutrient removal, and aquatic ecosystems at watershed scales, particularly in mixed land cover and land use systems. We use the Visualizing Ecosystem Land Management Assessments (VELMA) model to evaluate the effects of different LID practices on daily and long-term watershed-scale hydrology, including infiltration surface runoff. We focus on Shayler Crossing (SHC) watershed, a mixed land cover (61% urban, 24% agriculture, 15% forest) subwatershed of the East Fork Little Miami River watershed, Ohio, United States, with a drainage area of 0.94 km2. The model was calibrated to daily stream flow at the outlet of SHC watershed from 2009 to 2010 and was applied to evaluate diverse distributions (at 25% to 100% implementation levels) and types (e.g., pervious pavement and rain gardens) of LID across the watershed. Results show reduced surface water runoff and higher rates of infiltration concomitant with increasing LID implementation levels; however, this response varies between different LID practices. The highest magnitude response in streamflow at the watershed outlet is evident when a combination of LID practices is applied. The combined scenarios elucidate that the diverse watershed-scale hydrological responses of LID practices depend primarily on the type and extent of the implemented practices. Our work provides a key advancement toward improving current understanding of the effectiveness and efficiencies of LID approaches in mixed land cover watersheds.

Anatomy of a local-scale drought: Application of assimilated remote sensing products, crop model, and statistical methods to an agricultural drought study

NASA Astrophysics Data System (ADS)

Mishra, Ashok K.; Ines, Amor V. M.; Das, Narendra N.; Prakash Khedun, C.; Singh, Vijay P.; Sivakumar, Bellie; Hansen, James W.

2015-07-01

Drought is of global concern for society but it originates as a local problem. It has a significant impact on water quantity and quality and influences food, water, and energy security. The consequences of drought vary in space and time, from the local scale (e.g. county level) to regional scale (e.g. state or country level) to global scale. Within the regional scale, there are multiple socio-economic impacts (i.e., agriculture, drinking water supply, and stream health) occurring individually or in combination at local scales, either in clusters or scattered. Even though the application of aggregated drought information at the regional level has been useful in drought management, the latter can be further improved by evaluating the structure and evolution of a drought at the local scale. This study addresses a local-scale agricultural drought anatomy in Story County in Iowa, USA. This complex problem was evaluated using assimilated AMSR-E soil moisture and MODIS-LAI data into a crop model to generate surface and sub-surface drought indices to explore the anatomy of an agricultural drought. Quantification of moisture supply in the root zone remains a gray area in research community, this challenge can be partly overcome by incorporating assimilation of soil moisture and leaf area index into crop modeling framework for agricultural drought quantification, as it performs better in simulating crop yield. It was noted that the persistence of subsurface droughts is in general higher than surface droughts, which can potentially improve forecast accuracy. It was found that both surface and subsurface droughts have an impact on crop yields, albeit with different magnitudes, however, the total water available in the soil profile seemed to have a greater impact on the yield. Further, agricultural drought should not be treated equal for all crops, and it should be calculated based on the root zone depth rather than a fixed soil layer depth. We envisaged that the results of this study will enhance our understanding of agricultural droughts in different parts of the world.

Towards large scale modelling of wetland water dynamics in northern basins.

NASA Astrophysics Data System (ADS)

Pedinotti, V.; Sapriza, G.; Stone, L.; Davison, B.; Pietroniro, A.; Quinton, W. L.; Spence, C.; Wheater, H. S.

2015-12-01

Understanding the hydrological behaviour of low topography, wetland-dominated sub-arctic areas is one major issue needed for the improvement of large scale hydrological models. These wet organic soils cover a large extent of Northern America and have a considerable impact on the rainfall-runoff response of a catchment. Moreover their strong interactions with the lower atmosphere and the carbon cycle make of these areas a noteworthy component of the regional climate system. In the framework of the Changing Cold Regions Network (CCRN), this study aims at providing a model for wetland water dynamics that can be used for large scale applications in cold regions. The modelling system has two main components : a) the simulation of surface runoff using the Modélisation Environmentale Communautaire - Surface and Hydrology (MESH) land surface model driven with several gridded atmospheric datasets and b) the routing of surface runoff using the WATROUTE channel scheme. As a preliminary study, we focus on two small representative study basins in Northern Canada : Scotty Creek in the lower Liard River valley of the Northwest Territories and Baker Creek, located a few kilometers north of Yellowknife. Both areas present characteristic landscapes dominated by a series of peat plateaus, channel fens, small lakes and bogs. Moreover, they constitute important fieldwork sites with detailed data to support our modelling study. The challenge of our new wetland model is to represent the hydrological functioning of the various landscape units encountered in those watersheds and their interactions using simple numerical formulations that can be later extended to larger basins such as the Mackenzie river basin. Using observed datasets, the performance of the model to simulate the temporal evolution of hydrological variables such as the water table depth, frost table depth and discharge is assessed.

Assessing the Impact of Urbanization on Direct Runoff Using Improved Composite CN Method in a Large Urban Area.

PubMed

Li, Chunlin; Liu, Miao; Hu, Yuanman; Shi, Tuo; Zong, Min; Walter, M Todd

2018-04-17

Urbanization is one of the most widespread anthropogenic activities, which brings a range of physical and biochemical changes to hydrological system and processes. Increasing direct runoff caused by land use change has become a major challenge for urban ecological security. Reliable prediction of the quantity and rate of surface runoff is an inherently difficult and time-consuming task for large ungauged urban areas. In this study, we combined Geographic Information System and remote sensing technology with an improved Soil Conservation Service curve number model to evaluate the effects of land use change on direct runoff volume of the four-ring area in Shenyang, China, and analyzed trends of direct runoff at different scales. Through analyzing trends of direct runoff from 1984 to 2015 at different scales, we explored how urbanization and other potential factors affect direct runoff changes. Total direct runoff volume increased over time, and trends varied from the inner urban area to suburban area. Zones 1 and 2 had a tendency toward decreasing direct runoff volume and risks, while Zones 3 and 4 showed gradual increases at both regional and pixel scales. The most important influence on direct runoff change was urban surface change caused by urbanization. This study presents a framework for identifying hotspots of runoff increase, which can provide important guidance to urban managers in future green infrastructure planning, in the hopes of improving the security of urban water ecological patterns.

Assessing the Impact of Urbanization on Direct Runoff Using Improved Composite CN Method in a Large Urban Area

PubMed Central

Li, Chunlin; Liu, Miao; Hu, Yuanman; Shi, Tuo; Zong, Min; Walter, M. Todd

2018-01-01

Urbanization is one of the most widespread anthropogenic activities, which brings a range of physical and biochemical changes to hydrological system and processes. Increasing direct runoff caused by land use change has become a major challenge for urban ecological security. Reliable prediction of the quantity and rate of surface runoff is an inherently difficult and time-consuming task for large ungauged urban areas. In this study, we combined Geographic Information System and remote sensing technology with an improved Soil Conservation Service curve number model to evaluate the effects of land use change on direct runoff volume of the four-ring area in Shenyang, China, and analyzed trends of direct runoff at different scales. Through analyzing trends of direct runoff from 1984 to 2015 at different scales, we explored how urbanization and other potential factors affect direct runoff changes. Total direct runoff volume increased over time, and trends varied from the inner urban area to suburban area. Zones 1 and 2 had a tendency toward decreasing direct runoff volume and risks, while Zones 3 and 4 showed gradual increases at both regional and pixel scales. The most important influence on direct runoff change was urban surface change caused by urbanization. This study presents a framework for identifying hotspots of runoff increase, which can provide important guidance to urban managers in future green infrastructure planning, in the hopes of improving the security of urban water ecological patterns. PMID:29673182

A highly permeable and enhanced surface area carbon-cloth electrode for vanadium redox flow batteries

NASA Astrophysics Data System (ADS)

Zhou, X. L.; Zhao, T. S.; Zeng, Y. K.; An, L.; Wei, L.

2016-10-01

In this work, a high-performance porous electrode, made of KOH-activated carbon-cloth, is developed for vanadium redox flow batteries (VRFBs). The macro-scale porous structure in the carbon cloth formed by weaving the carbon fibers in an ordered manner offers a low tortuosity (∼1.1) and a broad pore distribution from 5 μm to 100 μm, rendering the electrode a high hydraulic permeability and high effective ionic conductivity, which are beneficial for the electrolyte flow and ion transport through the porous electrode. The use of KOH activation method to create nano-scale pores on the carbon-fiber surfaces leads to a significant increase in the surface area for redox reactions from 2.39 m2 g-1 to 15.4 m2 g-1. The battery assembled with the present electrode delivers an energy efficiency of 80.1% and an electrolyte utilization of 74.6% at a current density of 400 mA cm-2, as opposed to an electrolyte utilization of 61.1% achieved by using a conventional carbon-paper electrode. Such a high performance is mainly attributed to the combination of the excellent mass/ion transport properties and the high surface area rendered by the present electrode. It is suggested that the KOH-activated carbon-cloth electrode is a promising candidate in redox flow batteries.

Hydroxyapatite formation on titania-based materials in a solution mimicking body fluid: Effects of manganese and iron addition in anatase.

PubMed

Shin, Euisup; Kim, Ill Yong; Cho, Sung Baek; Ohtsuki, Chikara

2015-03-01

Hydroxyapatite formation on the surfaces of implanted materials plays an important role in osteoconduction of bone substitutes in bone tissues. Titania hydrogels are known to instigate hydroxyapatite formation in a solution mimicking human blood plasma. To date, the relationship between the surface characteristics of titania and hydroxyapatite formation on its surface remains unclear. In this study, titania powders with varying surface characteristics were prepared by addition of manganese or iron to examine hydroxyapatite formation in a type of simulated body fluid (Kokubo solution). Hydroxyapatite formation was monitored by observation of deposited particles with scale-like morphology on the prepared titania powders. The effect of the titania surface characteristics, i.e., crystal structure, zeta potential, hydroxy group content, and specific surface area, on hydroxyapatite formation was examined. Hydroxyapatite formation was observed on the surface of titania powders that were primarily anatase, and featured a negative zeta potential and low specific surface areas irrespective of the hydroxy group content. High specific surface areas inhibited the formation of hydroxyapatite because calcium and phosphate ions were mostly consumed by adsorption on the titania surface. Thus, these surface characteristics of titania determine its osteoconductivity following exposure to body fluid. Copyright © 2014 Elsevier B.V. All rights reserved.

The influence of surface type on the absorbed radiation by a human under hot, dry conditions

NASA Astrophysics Data System (ADS)

Hardin, A. W.; Vanos, J. K.

2018-01-01

Given the predominant use of heat-retaining materials in urban areas, numerous studies have addressed the urban heat island mitigation potential of various "cool" options, such as vegetation and high-albedo surfaces. The influence of altered radiational properties of such surfaces affects not only the air temperature within a microclimate, but more importantly the interactions of long- and short-wave radiation fluxes with the human body. Minimal studies have assessed how cool surfaces affect thermal comfort via changes in absorbed radiation by a human ( R abs) using real-world, rather than modeled, urban field data. The purpose of the current study is to assess the changes in the absorbed radiation by a human—a critical component of human energy budget models—based on surface type on hot summer days (air temperatures > 38.5∘C). Field tests were conducted using a high-end microclimate station under predominantly clear sky conditions over ten surfaces with higher sky view factors in Lubbock, Texas. Three methods were used to measure and estimate R abs: a cylindrical radiation thermometer (CRT), a net radiometer, and a theoretical estimation model. Results over dry surfaces suggest that the use of high-albedo surfaces to reduce overall urban heat gain may not improve acute human thermal comfort in clear conditions due to increased reflected radiation. Further, the use of low-cost instrumentation, such as the CRT, shows potential in quantifying radiative heat loads within urban areas at temporal scales of 5-10 min or greater, yet further research is needed. Fine-scale radiative information in urban areas can aid in the decision-making process for urban heat mitigation using non-vegetated urban surfaces, with surface type choice is dependent on the need for short-term thermal comfort, or reducing cumulative heat gain to the urban fabric.

Monitoring Ecosystem Dynamics Ecosystem Using Hyperspectral Reflectance and a Robotic Tram System in Barrow Alaska

NASA Astrophysics Data System (ADS)

Goswami, S.; Gamon, J. A.; Tweedie, C. E.

2012-12-01

Understanding the future state of the earth system requires improved knowledge of ecosystem dynamics and long term observations of how ecosystem structures and functions are being impacted by global change. Improving remote sensing methods is essential for such advancement because satellite remote sensing is the only means by which landscape to continental-scale change can be observed. The Arctic appears to be impacted by climate change more than any other region on Earth. Arctic terrestrial ecosystems comprise only 6% of the land surface area on Earth yet contain an estimated 25% of global soil organic carbon, most of which is stored in permafrost. If projected increases in plant productivity do not offset forecast losses of soil carbon to the atmosphere as greenhouse gases, regional to global greenhouse warming could be enhanced. Soil moisture is an important control of land-atmosphere carbon exchange in arctic terrestrial ecosystems. However, few studies to date have examined using remote sensing, or developed remote sensing methods for observing the complex interplay between soil moisture and plant phenology and productivity in arctic landscapes. This study was motivated by this knowledge gap and addressed the following questions as a contribution to a large scale, multi investigator flooding and draining experiment funded by the National Science Foundation near Barrow, Alaska from 2005 - 2009. 1. How can optical remote sensing be used to monitor the surface hydrology of arctic landscapes? 2. What are the spatio-temporal dynamics of land-surface phenology (NDVI) in the study area and do hydrological treatment has any effect on inter-annual patterns? A new spectral index, the normalized difference surface water index (NDSWI) was developed and tested at multiple spatial and temporal scales. NDSWI uses the 460nm (blue) and 1000nm (IR) bands and was developed to capture surface hydrological dynamics in the study area using the robotic tram system. When applied to high spatial resolution satellite imagery, NDSWI was also able to capture changes in surface hydrology at the landscape scale. Interannual patterns of landsurface phenology (measured with the normalized difference vegetation index - NDVI) unexpectedly lacked marked differences under experimental conditions. Measurement of NDVI was, however, compromised when WTD was above ground level. NDVI and NDSWI were negatively correlated when WTD was above ground level, which held when scaled to MODIS imagery collected from satellite, suggesting that published findings showing a 'greening of the Arctic' may be related to a 'drying of the Arctic' in landscapes dominated by vegetated landscapes where WTD is close to ground level.

Roughness topographical effects on mean momentum and stress budgets in developed turbulent channel flows

NASA Astrophysics Data System (ADS)

Aghaei Jouybari, Mostafa; Yuan, Junlin

2017-11-01

Direct numerical simulations of turbulent channel flows are carried out over two surfaces: a synthesized sand-grain surface and a realistic turbine roughness that is characterized by more prominent large-scale surface features. To separate the effects of wall-normal variation of the roughness area fraction from the (true) variation of flow statistics, the governing equations are area-averaged using intrinsic averaging, contrary to the usually practice based on the total area (i.e., superficial averaging). Additional terms appear in the mean-momentum equation resulted from the wall-normal variation of the solid fraction and play a role in the near-wall balance. Results from surfaces with a step solidity function (e.g., cubes) will also be discussed. Compared to the sand grains, the turbine surface generates stronger form-induced fluctuations, despite weaker dispersive shear stress. This is associated with more significant form-induced productions (comparable to shear production) in Reynolds stress budgets, weaker pressure work, and, consequently, more anisotropic redistribution of turbulent kinetic energy in the roughness sublayer, which potentially leads to different turbulent responses between the two surfaces in non-equilibrium flows.

Building the ensemble flood prediction system by using numerical weather prediction data: Case study in Kinu river basin, Japan

NASA Astrophysics Data System (ADS)

Ishitsuka, Y.; Yoshimura, K.

2016-12-01

Floods have a potential to be a major source of economic or human damage caused by natural disasters. Flood prediction systems were developed all over the world and to treat the uncertainty of the prediction ensemble simulation is commonly adopted. In this study, ensemble flood prediction system using global scale land surface and hydrodynamic model was developed. The system requests surface atmospheric forcing and Land Surface Model, MATSIRO, calculates runoff. Those generated runoff is inputted to hydrodynamic model CaMa-Flood to calculate discharge and flood inundation. CaMa-Flood can simulate flood area and its fraction by introducing floodplain connected to river channel. Forecast leadtime was set 39hours according to forcing data. For the case study, the flood occurred at Kinu river basin, Japan in 2015 was hindcasted. In a 1761 km² Kinu river basin, 3-days accumulated average rainfall was 384mm and over 4000 people was left in the inundated area. Available ensemble numerical weather prediction data at that time was inputted to the system in a resolution of 0.05 degrees and 1hour time step. As a result, the system predicted the flood occurrence by 45% and 84% at 23 and 11 hours before the water level exceeded the evacuation threshold, respectively. Those prediction lead time may provide the chance for early preparation for the floods such as levee reinforcement or evacuation. Adding to the discharge, flood area predictability was also analyzed. Although those models were applied for Japan region, this system can be applied easily to other region or even global scale. The areal flood prediction in meso to global scale would be useful for detecting hot zones or vulnerable areas over each region.

Large-area Soil Moisture Surveys Using a Cosmic-ray Rover: Approaches and Results from Australia

NASA Astrophysics Data System (ADS)

Hawdon, A. A.; McJannet, D. L.; Renzullo, L. J.; Baker, B.; Searle, R.

2017-12-01

Recent improvements in satellite instrumentation has increased the resolution and frequency of soil moisture observations, and this in turn has supported the development of higher resolution land surface process models. Calibration and validation of these products is restricted by the mismatch of scales between remotely sensed and contemporary ground based observations. Although the cosmic ray neutron soil moisture probe can provide estimates soil moisture at a scale useful for the calibration and validation purposes, it is spatially limited to a single, fixed location. This scaling issue has been addressed with the development of mobile soil moisture monitoring systems that utilizes the cosmic ray neutron method, typically referred to as a `rover'. This manuscript describes a project designed to develop approaches for undertaking rover surveys to produce soil moisture estimates at scales comparable to satellite observations and land surface process models. A custom designed, trailer-mounted rover was used to conduct repeat surveys at two scales in the Mallee region of Victoria, Australia. A broad scale survey was conducted at 36 x 36 km covering an area of a standard SMAP pixel and an intensive scale survey was conducted over a 10 x 10 km portion of the broad scale survey, which is at a scale equivalent to that used for national water balance modelling. We will describe the design of the rover, the methods used for converting neutron counts into soil moisture and discuss factors controlling soil moisture variability. We found that the intensive scale rover surveys produced reliable soil moisture estimates at 1 km resolution and the broad scale at 9 km resolution. We conclude that these products are well suited for future analysis of satellite soil moisture retrievals and finer scale soil moisture models.

Multi-scale Fracture Patterns Associated with a Complex Anticline Structure: Insights from Field Outcrop Analogues of the Jebel Hafit Pericline, Al Ain-UAE

NASA Astrophysics Data System (ADS)

Kokkalas, S.; Jones, R. R.; Long, J. J.; Zampos, M.; Wilkinson, M. W.; Gilment, S.

2017-12-01

The formation of folds and their associated fracture patterns plays an important role in controlling the migration and concentration of fluids within the upper crust. Prediction of fracture patterns from various fold shapes and kinematics still remains poorly understood in terms of spatial and temporal distribution of fracture sets. Thus, a more detailed field-based multi scale approach is required to better constrain 3D models of fold-fracture relationships, which are critical for reservoir characterization studies. In order to generate reservoir-scale fracture models representative fracture properties across a wider range of scales are needed. For this reason we applied modern geospatial technologies, including terrestrial LiDAR, photogrammetry and satellite images in the asymmetric, east verging, four-way closure Jebel Hafit anticline, in the eastern part of the United Arab Emirates. The excellent surface outcrops allowed the rapid acquisition of extensive areas of fracture data from both limbs and fold hinge area of the anticline, even from large areas of steep exposure that are practically inaccessible on foot. The digital outcrops provide longer 1D transects, and 2D or 3D surface datasets and give more robust data, particularly for fracture heights, lengths, spacing, clustering, termination and connectivity. The fracture patterns across the folded structure are more complex than those predicted from conceptual models and geomechanical fracture modeling. Mechanical layering, pre-existing structures and sedimentation during fold growth seem to exert a critical influence in the development of fracture systems within Jebel Hafit anticline and directly affect fracture orientations, spacing/intensity, segmentation and connectivity. Seismic and borehole data provide additional constraints on the sub-surface fold geometry and existence of large-scale thrusting in the core of the anticline. The complexity of the relationship between fold geometry and fracture intensity is presented and the implications for prediction of fracture networks in naturally fractured reservoirs are discussed.

Driving force for hydrophobic interaction at different length scales.

PubMed

Zangi, Ronen

2011-03-17

We study by molecular dynamics simulations the driving force for the hydrophobic interaction between graphene sheets of different sizes down to the atomic scale. Similar to the prediction by Lum, Chandler, and Weeks for hard-sphere solvation [J. Phys. Chem. B 1999, 103, 4570-4577], we find the driving force to be length-scale dependent, despite the fact that our model systems do not exhibit dewetting. For small hydrophobic solutes, the association is purely entropic, while enthalpy favors dissociation. The latter is demonstrated to arise from the enhancement of hydrogen bonding between the water molecules around small hydrophobes. On the other hand, the attraction between large graphene sheets is dominated by enthalpy which mainly originates from direct solute-solute interactions. The crossover length is found to be inside the range of 0.3-1.5 nm(2) of the surface area of the hydrophobe that is eliminated in the association process. In the large-scale regime, different thermodynamic properties are scalable with this change of surface area. In particular, upon dimerization, a total and a water-induced stabilization of approximately 65 and 12 kJ/mol/nm(2) are obtained, respectively, and on average around one hydrogen bond is gained per 1 nm(2) of graphene sheet association. Furthermore, the potential of mean force between the sheets is also scalable except for interplate distances smaller than 0.64 nm which corresponds to the region around the barrier for removing the last layer of water. It turns out that, as the surface area increases, the relative height of the barrier for association decreases and the range of attraction increases. It is also shown that, around small hydrophobic solutes, the lifetime of the hydrogen bonds is longer than in the bulk, while around large hydrophobes it is the same. Nevertheless, the rearrangement of the hydrogen-bond network for both length-scale regimes is slower than in bulk water. © 2011 American Chemical Society

Erosional and depositional history of central Chryse Planitia

NASA Technical Reports Server (NTRS)

Crumpler, L. S.

1992-01-01

This map uses high resolution image data to assess the detailed depositional and erosional history of part of Chryse Planitia. This area is significant to the study of the global geology of Mars because it represents one of only two areas on the martian surface where planetary geologic mapping is assisted with 'ground truth.' In this case the ground truth was provided by Viking Lander 1. Additional questions addressed in this study are concerned with the following: the geologic context of the regional plains surface and the local surface of the Viking Lander 1 site; and the relative influence of volcanic, sedimentary, impact, aeolian, and tectonic processes at the regional and local scales.

Surface Forces Apparatus Measurements of Interactions between Rough and Reactive Calcite Surfaces.

PubMed

Dziadkowiec, Joanna; Javadi, Shaghayegh; Bratvold, Jon E; Nilsen, Ola; Røyne, Anja

2018-06-26

nm-Range forces acting between calcite surfaces in water affect macroscopic properties of carbonate rocks and calcite-based granular materials and are significantly influenced by calcite surface recrystallization. We suggest that the repulsive mechanical effects related to nm-scale surface recrystallization of calcite in water could be partially responsible for the observed decrease of cohesion in calcitic rocks saturated with water. Using the surface forces apparatus, we simultaneously followed the calcite reactivity and measured the forces in water in two surface configurations: between two rough calcite surfaces (CC) and between rough calcite and a smooth mica surface (CM). We used nm-scale rough, polycrystalline calcite films prepared by atomic layer deposition. We measured only repulsive forces in CC in CaCO 3 -saturated water, which was related to roughness and possibly to repulsive hydration effects. Adhesive or repulsive forces were measured in CM in CaCO 3 -saturated water depending on calcite roughness, and the adhesion was likely enhanced by electrostatic effects. The pull-off adhesive force in CM became stronger with time, and this increase was correlated with a decrease of roughness at contacts, the parameter which could be estimated from the measured force-distance curves. That suggested a progressive increase of real contact areas between the surfaces, caused by gradual pressure-driven deformation of calcite surface asperities during repeated loading-unloading cycles. Reactivity of calcite was affected by mass transport across nm- to μm-thick gaps between the surfaces. Major roughening was observed only for the smoothest calcite films, where gaps between two opposing surfaces were nm-thick over μm-sized areas and led to force of crystallization that could overcome confining pressures of the order of MPa. Any substantial roughening of calcite caused a significant increase of the repulsive mechanical force contribution.

Surface water classification and monitoring using polarimetric synthetic aperture radar

NASA Astrophysics Data System (ADS)

Irwin, Katherine Elizabeth

Surface water classification using synthetic aperture radar (SAR) is an established practice for monitoring flood hazards due to the high temporal and spatial resolution it provides. Surface water change is a dynamic process that varies both spatially and temporally, and can occur on various scales resulting in significant impacts on affected areas. Small-scale flooding hazards, caused by beaver dam failure, is an example of surface water change, which can impact nearby infrastructure and ecosystems. Assessing these hazards is essential to transportation and infrastructure maintenance. With current satellite missions operating in multiple polarizations, spatio-temporal resolutions, and frequencies, a comprehensive comparison between SAR products for surface water monitoring is necessary. In this thesis, surface water extent models derived from high resolution single-polarization TerraSAR-X (TSX) data, medium resolution dual-polarization TSX data and low resolution quad-polarization RADARSAT-2 (RS-2) data are compared. There exists a compromise between acquiring SAR data with a high resolution or high information content. Multi-polarization data provides additional phase and intensity information, which makes it possible to better classify areas of flooded vegetation and wetlands. These locations are often where fluctuations in surface water occur and are essential for understanding dynamic underlying processes. However, often multi-polarized data is acquired at a low resolution, which cannot image these zones effectively. High spatial resolution, single-polarization TSX data provides the best model of open water. However, these single-polarization observations have limited information content and are affected by shadow and layover errors. This often hinders the classification of other land cover types. The dual-polarization TSX data allows for the classification of flooded vegetation, but classification is less accurate compared to the quad-polarization RS-2 data. The RS-2 data allows for the discrimination of open water, marshes/fields and forested areas. However, the RS-2 data is less applicable to small scale surface water monitoring (e.g. beaver dam failure), due to its low spatial resolution. By understanding the strengths and weaknesses of available SAR technology, an appropriate product can be chosen for a specific target application involving surface water change. This research benefits the eventual development of a space-based monitoring strategy over longer periods.

The managed clearing: An overlooked land-cover type in urbanizing regions?

PubMed

Singh, Kunwar K; Madden, Marguerite; Gray, Josh; Meentemeyer, Ross K

2018-01-01

Urban ecosystem assessments increasingly rely on widely available map products, such as the U.S. Geological Service (USGS) National Land Cover Database (NLCD), and datasets that use generic classification schemes to detect and model large-scale impacts of land-cover change. However, utilizing existing map products or schemes without identifying relevant urban class types such as semi-natural, yet managed land areas that account for differences in ecological functions due to their pervious surfaces may severely constrain assessments. To address this gap, we introduce the managed clearings land-cover type-semi-natural, vegetated land surfaces with varying degrees of management practices-for urbanizing landscapes. We explore the extent to which managed clearings are common and spatially distributed in three rapidly urbanizing areas of the Charlanta megaregion, USA. We visually interpreted and mapped fine-scale land cover with special attention to managed clearings using 2012 U.S. Department of Agriculture (USDA) National Agriculture Imagery Program (NAIP) images within 150 randomly selected 1-km2 blocks in the cities of Atlanta, Charlotte, and Raleigh, and compared our maps with National Land Cover Database (NLCD) data. We estimated the abundance of managed clearings relative to other land use and land cover types, and the proportion of land-cover types in the NLCD that are similar to managed clearings. Our study reveals that managed clearings are the most common land cover type in these cities, covering 28% of the total sampled land area- 6.2% higher than the total area of impervious surfaces. Managed clearings, when combined with forest cover, constitutes 69% of pervious surfaces in the sampled region. We observed variability in area estimates of managed clearings between the NAIP-derived and NLCD data. This suggests using high-resolution remote sensing imagery (e.g., NAIP) instead of modifying NLCD data for improved representation of spatial heterogeneity and mapping of managed clearings in urbanizing landscapes. Our findings also demonstrate the need to more carefully consider managed clearings and their critical ecological functions in landscape- to regional-scale studies of urbanizing ecosystems.

An analysis of spatial representativeness of air temperature monitoring stations

NASA Astrophysics Data System (ADS)

Liu, Suhua; Su, Hongbo; Tian, Jing; Wang, Weizhen

2018-05-01

Surface air temperature is an essential variable for monitoring the atmosphere, and it is generally acquired at meteorological stations that can provide information about only a small area within an r m radius ( r-neighborhood) of the station, which is called the representable radius. In studies on a local scale, ground-based observations of surface air temperatures obtained from scattered stations are usually interpolated using a variety of methods without ascertaining their effectiveness. Thus, it is necessary to evaluate the spatial representativeness of ground-based observations of surface air temperature before conducting studies on a local scale. The present study used remote sensing data to estimate the spatial distribution of surface air temperature using the advection-energy balance for air temperature (ADEBAT) model. Two target stations in the study area were selected to conduct an analysis of spatial representativeness. The results showed that one station (AWS 7) had a representable radius of about 400 m with a possible error of less than 1 K, while the other station (AWS 16) had the radius of about 250 m. The representable radius was large when the heterogeneity of land cover around the station was small.

The effect of short ground vegetation on terrestrial laser scans at a local scale

NASA Astrophysics Data System (ADS)

Fan, Lei; Powrie, William; Smethurst, Joel; Atkinson, Peter M.; Einstein, Herbert

2014-09-01

Terrestrial laser scanning (TLS) can record a large amount of accurate topographical information with a high spatial accuracy over a relatively short period of time. These features suggest it is a useful tool for topographical survey and surface deformation detection. However, the use of TLS to survey a terrain surface is still challenging in the presence of dense ground vegetation. The bare ground surface may not be illuminated due to signal occlusion caused by vegetation. This paper investigates vegetation-induced elevation error in TLS surveys at a local scale and its spatial pattern. An open, relatively flat area vegetated with dense grass was surveyed repeatedly under several scan conditions. A total station was used to establish an accurate representation of the bare ground surface. Local-highest-point and local-lowest-point filters were applied to the point clouds acquired for deriving vegetation height and vegetation-induced elevation error, respectively. The effects of various factors (for example, vegetation height, edge effects, incidence angle, scan resolution and location) on the error caused by vegetation are discussed. The results are of use in the planning and interpretation of TLS surveys of vegetated areas.

To make a land use inventory and its change with time and development. To investigate how this area in the semi-arid climate is developing, and the ecological impact with the construction of several government projects in Central Mexico

NASA Technical Reports Server (NTRS)

Acoustadelcampo, C. (Principal Investigator)

1974-01-01

The author has identified the following significant results. Comparison between ERTS-1 image scale 1:1,000,000 and CETENAL's charts scale 1:50,000 in irrigated land surface determination in one selected spot gave the following results: Surface on CETENAL's charts 129,900 Has. and arbitrarily we gave 100 percent to this value. Surface on image 122,400 Has., 94.5 percent of the first value. It is necessary to use all four bands to have optimum results on the interpretation. The Principal investigator made use of photointerpretation techniques only, mostly monoscopically.

An investigation of relationships between meso- and synoptic-scale phenomena

NASA Technical Reports Server (NTRS)

Scoggins, J. R.; Wood, J. E.; Fuelberg, H. E.; Read, W. L.

1972-01-01

Methods based on the vorticity equation, the adiabatic method, the curvature of the vertical wind profile, and the structure of synoptic waves are used to determine areas of positive vertical motion in the mid-troposphere for a period in each season. Parameters indicative of low-level moisture and conditional instability are areas in which mesoscale systems may be present. The best association between mesoscale and synoptic-scale phenomena was found for a period during December when synoptic-scale systems were well developed. A good association between meso- and synoptic-scale events also was found for a period during March, while the poorest association was found for a June period. Daytime surface heating apparently is an important factor in the formation of mesoscale systems during the summer. It is concluded that the formation of mesoscale phenomena may be determined essentially from synoptic-scale conditions during winter, late fall, and early spring.

Imaging surface contacts: Power law contact distributions and contact stresses in quartz, calcite, glass and acrylic plastic

USGS Publications Warehouse

Dieterich, J.H.; Kilgore, B.D.

1996-01-01

A procedure has been developed to obtain microscope images of regions of contact between roughened surfaces of transparent materials, while the surfaces are subjected to static loads or undergoing frictional slip. Static loading experiments with quartz, calcite, soda-lime glass and acrylic plastic at normal stresses to 30 MPa yield power law distributions of contact areas from the smallest contacts that can be resolved (3.5 ??m2) up to a limiting size that correlates with the grain size of the abrasive grit used to roughen the surfaces. In each material, increasing normal stress results in a roughly linear increase of the real area of contact. Mechanisms of contact area increase are by growth of existing contacts, coalescence of contacts and appearance of new contacts. Mean contacts stresses are consistent with the indentation strength of each material. Contact size distributions are insensitive to normal stress indicating that the increase of contact area is approximately self-similar. The contact images and contact distributions are modeled using simulations of surfaces with random fractal topographies. The contact process for model fractal surfaces is represented by the simple expedient of removing material at regions where surface irregularities overlap. Synthetic contact images created by this approach reproduce observed characteristics of the contacts and demonstrate that the exponent in the power law distributions depends on the scaling exponent used to generate the surface topography.

Scales microstructure of snakes from the Egyptian area.

PubMed

Allam, Ahmed A; Abo-Eleneen, Rasha E

2012-11-01

The morphology of many organisms seems to be related to the environments in which they live. Many snakes are so similar in their morphological patterns that it becomes quite difficult to distinguish any adaptive divergence that may have occurred. Many authors have suggested that the microstructure of the reptile's scales has important functional value. Herein, we investigate variations on the micromorphology of the external surface of dorsal scales on the head, the mid-body region (trunk), and the tail of Rhomphotyphlops braminus (Typhlopidae), Eryx jaculus (Boidae), Psammophis sibilans (Colubridae), Naja haje (Elapidae) and Echis carinatus (Viperidae). The specimens were metallized and analyzed by scanning electron microscopy. All species displayed unique dorsal scale surface microstructures of the investigated regions. The microstructural pattern of the scales of head, trunk, and tail differs in different species of these snakes. In conclusion, we detected ecomorphologic relationships between extant dorsal scale microstructures and snake microhabitat, enabling us to hypothesize that environmental pressures have significant influences not only on these animals' macrostructure, but also on its microstructure as well.

Hydrologic reconnaissance of the Kolob, Alton, and Kaiparowits Plateau coal fields, south-central Utah

USGS Publications Warehouse

Plantz, Gerald G.

1985-01-01

The study area in south-central Utah (fig. 1) is noted for its large coal reserves in the Alton, Kolob, and Kaiparowits Plateau coal fields. The area also is noted for its scenic beauty and general scarcity of water. Although there has been very little development of the coal resources through 1983, there is a potential for large-scale development with both surface- and underground-mining methods. Mining of coal could have significant effects on the quantity and quality of the water resources. The purpose of this atlas is to define the surface- and ground-water resources of the area and to identify the potential effects on these resources by coal mining.

Large area and deep sub-wavelength interference lithography employing odd surface plasmon modes.

PubMed

Liu, Liqin; Luo, Yunfei; Zhao, Zeyu; Zhang, Wei; Gao, Guohan; Zeng, Bo; Wang, Changtao; Luo, Xiangang

2016-07-28

In this paper, large area and deep sub-wavelength interference patterns are realized experimentally by using odd surface plasmon modes in the metal/insulator/metal structure. Theoretical investigation shows that the odd modes possesses much higher transversal wave vector and great inhibition of tangential electric field components, facilitating surface plasmon interference fringes with high resolution and contrast in the measure of electric field intensity. Interference resist patterns with 45 nm (∼λ/8) half-pitch, 50 nm depth, and area size up to 20 mm × 20 mm were obtained by using 20 nm Al/50 nm photo resist/50 nm Al films with greatly reduced surface roughness and 180 nm pitch exciting grating fabricated with conventional laser interference lithography. Much deeper resolution down to 19.5 nm is also feasible by decreasing the thickness of PR. Considering that no requirement of expensive EBL or FIB tools are employed, it provides a cost-effective way for large area and nano-scale fabrication.

Relation of urbanization to stream habitat and geomorphic characteristics in nine metropolitan areas of the United States

USGS Publications Warehouse

Fitzpatrick, Faith A.; Peppler, Marie C.

2010-01-01

The relation of urbanization to stream habitat and geomorphic characteristics was examined collectively and individually for nine metropolitan areas of the United States?Portland, Oregon; Salt Lake City, Utah; Denver, Colorado; Dallas?Forth Worth, Texas; Milwaukee?Green Bay, Wisconsin; Birmingham, Alabama; Atlanta, Georgia; Raleigh, North Carolina; and Boston, Massachusetts. The study was part of a larger study conducted by the U.S. Geological Survey from 1999 to 2004 to examine the effects of urbanization on the physical, chemical, and biological components of stream ecosystems. The objectives of the current study were to determine how stream habitat and geomorphic characteristics relate to different aspects of urbanization across a variety of diverse environmental settings and spatial scales. A space-for-time rural-to-urban land-cover gradient approach was used. Reach-scale habitat data and geomorphic characteristic data were collected once during low flow and included indicators of potential habitat degradation such as measures of channel geometry and hydraulics, streambed substrate, low-flow reach volume (an estimate of base-flow conditions), habitat complexity, and riparian/bank conditions. Hydrologic metrics included in the analyses were those expected to be altered by increases in impervious surfaces, such as high-flow frequency and duration, flashiness, and low-flow duration. Other natural and human features, such as reach-scale channel engineering, geologic setting, and slope, were quantified to identify their possible confounding influences on habitat relations with watershed-scale urbanization indicators. Habitat and geomorphic characteristics were compared to several watershed-scale indicators of urbanization, natural landscape characteristics, and hydrologic metrics by use of correlation analyses and stepwise linear regression. Habitat and geomorphic characteristics were related to percentages of impervious surfaces only in some metropolitan areas and environmental settings. The relations between watershed-scale indicators of urbanization and stream habitat depended on physiography and climate, hydrology, pre-urban channel alterations, reach-scale slope and presence of bedrock, and amount of bank stabilization and grade control. Channels increased in size with increasing percentages of impervious surfaces in southeastern and midwestern metropolitan areas regardless of whether the pre-existing land use was forest or agriculture. The amount of enlargement depended on annual precipitation and frequency of high-flow events. The lack of a relation between channel enlargement and increasing impervious surfaces in other metropolitan areas was thought to be confounded by pre-urbanization hydrologic and channel alterations. Direct relations of channel shape and streambed substrate to urbanization were variable or lacking, probably because the type, amount, and source of sediment are dependent on the phase of urbanization. Reach-scale slope also was important for determining variations in streambed substrate and habitat complexity (percentage of riffles and runs). Urbanization-associated changes in reach-scale riparian vegetation varied geographically, partially depending on pre-existing riparian vegetation characteristics. Bank erosion increased in Milwaukee?Green Bay and Boston urban streams, and bank erosion also increased with an increase in a streamflow flashiness index. However, potential relations likely were confounded by the frequent use of channel stabilization and bank protection in urban settings. Low-flow reach volume did not decrease with increasing urbanization, but instead was related to natural landscape characteristics and possibly other unmeasured factors. The presence of intermittent bedrock in some sampled reaches likely limited some geomorphic responses to urbanization, such as channel bed erosion. Results from this study emphasize the importance of including a wide range of landscape variables at m

Effect of wildfires on surface reflectance from a savanna ecosystem

NASA Astrophysics Data System (ADS)

Poudyal, R.; Gatebe, C. K.; Ichoku, C. M.; Varnai, T.

2015-12-01

During an airborne field campaign in South Africa in 2005, NASA's Cloud Absorption Radiometer (CAR) flew aboard South Africa Weather Service, Aerocommander 690A and measured surface bidirectional reflectance-distribution function (BRDF) over savanna comprised mostly of grasses and a few scattered trees. Savannas cover half the surface of Africa, large areas of Australia, South America, and India. . The region that was studied is located in Kruger National Park in northeastern South Africa, which was heavily affected by the wildfires. The CAR measured surface reflectance along its flight path covering both burned and unburned areas. . In this study, we compared surface reflectance between burnt and un-burnt areas at various wavelengths (340nm, 380nm, 472nm, 682nm, 870nm, 1036nm, 1219nm, 1273nm, and 2205nm) at satellite sub-pixel scales. We found a relative burnt surface reflectance decrease of between 8 and 65% due to fires. These results not only serve to highlight the importance of biomass burning and effects on the energy budgets, but also the need to determine the effects of albedo changes due to fires on soil moisture budget, evapotranspiration, infiltration, and runoff, all of which govern the land-surface component of the water cycle.

Usability of small impact craters on small surface areas in crater count dating: Analysing examples from the Harmakhis Vallis outflow channel, Mars

NASA Astrophysics Data System (ADS)

Kukkonen, S.; Kostama, V.-P.

2018-05-01

The availability of very high-resolution images has made it possible to extend crater size-frequency distribution studies to small, deca/hectometer-scale craters. This has enabled the dating of small and young surface units, as well as recent, short-time and small-scale geologic processes that have occurred on the units. Usually, however, the higher the spatial resolution of space images is, the smaller area is covered by the images. Thus the use of single, very high-resolution images in crater count age determination may be debatable if the images do not cover the studied region entirely. Here we compare the crater count results for the floor of the Harmakhis Vallis outflow channel obtained from the images of the ConTeXt camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) aboard the Mars Reconnaissance Orbiter (MRO). The CTX images enable crater counts for entire units on the Harmakhis Vallis main valley, whereas the coverage of the higher-resolution HiRISE images is limited and thus the images can only be used to date small parts of the units. Our case study shows that the crater count data based on small impact craters and small surface areas mainly correspond with the crater count data based on larger craters and more extensive counting areas on the same unit. If differences between the results were founded, they could usually be explained by the regional geology. Usually, these differences appeared when at least one cratering model age is missing from either of the crater datasets. On the other hand, we found only a few cases in which the cratering model ages were completely different. We conclude that the crater counts using small impact craters on small counting areas provide useful information about the geological processes which have modified the surface. However, it is important to remember that all the crater counts results obtained from a specific counting area always primarily represent the results from the counting area-not the whole unit. On the other hand, together with crater count results from extensive counting areas and lower-resolution images, crater counts on small counting areas but by using very high-resolution images is a very valuable tool for obtaining unique additional information about the local processes on the surface units.

Surficial Geologic Map of the Clinton-Concord-Grafton-Medfield 12-Quadrangle Area in East Central Massachusetts

USGS Publications Warehouse

Stone, Janet R.; Stone, Byron D.

2006-01-01

The surficial geologic map shows the distribution of nonlithified earth materials at land surface in an area of twelve 7.5-minute quadrangles (total 660 square miles) in east-central Massachusetts. The geologic map differentiates surficial materials of Quaternary age on the basis of their lithologic characteristics (grain size, sedimentary structures, mineral and rock-particle composition), constructional geomorphic features, stratigraphic relationships, and age. Surficial earth materials significantly affect human use of the land, and an accurate description of their distribution is particularly important for water resources, construction aggregate resources, earth-surface hazards assessments, and land-use decisions. This compilation of surficial geologic materials is an interim product that defines the areas of exposed bedrock, and the boundaries between glacial till, glacial stratified deposits, and overlying postglacial deposits. This work is part of a comprehensive study to produce a statewide digital map of the surficial geology at a 1:24,000-scale level of accuracy. This report includes explanatory text (PDF), a regional map at 1:50,000 scale (PDF), quadrangle maps at 1:24,000 scale (12 PDF files), GIS data layers (ArcGIS shapefiles), scanned topographic base maps (TIF), metadata for the GIS layers, and a readme.txt file.

Surface-material maps of Viking landing sites on Mars

NASA Technical Reports Server (NTRS)

Moore, H. J.; Keller, J. M.

1991-01-01

Researchers mapped the surface materials at the Viking landing sites on Mars to gain a better understanding of the materials and rock populations at the sites and to provide information for future exploration. The maps extent to about 9 m in front of each lander and are about 15 m wide - an area comparable to the area of a pixel in high resolution Viking Orbiter images. The maps are divided into the near and far fields. Data for the near fields are from 1/10 scale maps, umpublished maps, and lander images. Data for the far fields are from 1/20 scale contour maps, contoured lander camera mosaics, and lander images. Rocks are located on these maps using stereometric measurements and the contour maps. Frequency size distribution of rocks and the responses of soil-like materials to erosion by engine exhausts during landings are discussed.

Two-probe STM experiments at the atomic level.

PubMed

Kolmer, Marek; Olszowski, Piotr; Zuzak, Rafal; Godlewski, Szymon; Joachim, Christian; Szymonski, Marek

2017-11-08

Direct characterization of planar atomic or molecular scale devices and circuits on a supporting surface by multi-probe measurements requires unprecedented stability of single atom contacts and manipulation of scanning probes over large, nanometer scale area with atomic precision. In this work, we describe the full methodology behind atomically defined two-probe scanning tunneling microscopy (STM) experiments performed on a model system: dangling bond dimer wire supported on a hydrogenated germanium (0 0 1) surface. We show that 70 nm long atomic wire can be simultaneously approached by two independent STM scanners with exact probe to probe distance reaching down to 30 nm. This allows direct wire characterization by two-probe I-V characteristics at distances below 50 nm. Our technical results presented in this work open a new area for multi-probe research, which can be now performed with precision so far accessible only by single-probe scanning probe microscopy (SPM) experiments.

A MEMS-enabled 3D zinc-air microbattery with improved discharge characteristics based on a multilayer metallic substructure

NASA Astrophysics Data System (ADS)

Armutlulu, A.; Fang, Y.; Kim, S. H.; Ji, C. H.; Bidstrup Allen, S. A.; Allen, M. G.

2011-10-01

This paper reports the design, fabrication and testing of a three-dimensional zinc-air microbattery with improved areal energy density and areal capacity, particularly at high discharge rates. The device is based on a multilayer, micron-scale, low-resistance metallic skeleton with an improved surface area. This skeleton consists of alternating Cu and Ni layers supporting Zn as electrodeposited anode electrode, and provides a high surface area, low-resistance path for electron transfer. A proof-of-concept zinc-air microbattery based on this technology was developed, characterized and compared with its two-dimensional thin-film counterparts fabricated on the same footprint area with equal amount of the Zn anode electrode. Using this approach, we were able to improve a single-layer initial structure with a surface area of 1.3 mm2 to a scaffold structure with ten layers having a surface area of 15 mm2. Discharging through load resistances ranging from 100 to 3000 Ω, the areal energy density and areal capacity of the microbattery were measured as 2.5-3 mWh cm-2 and ~2.5 mAh cm-2, respectively.

Chapter 4. Predicting post-fire erosion and sedimentation risk on a landscape scale

USGS Publications Warehouse

MacDonald, L.H.; Sampson, R.; Brady, D.; Juarros, L.; Martin, Deborah

2000-01-01

Historic fire suppression efforts have increased the likelihood of large wildfires in much of the western U.S. Post-fire soil erosion and sedimentation risks are important concerns to resource managers. In this paper we develop and apply procedures to predict post-fire erosion and sedimentation risks on a pixel-, catchment-, and landscape-scale in central and western Colorado.Our model for predicting post-fire surface erosion risk is conceptually similar to the Revised Universal Soil Loss Equation (RUSLE). One key addition is the incorporation of a hydrophobicity risk index (HY-RISK) based on vegetation type, predicted fire severity, and soil texture. Post-fire surface erosion risk was assessed for each 90-m pixel by combining HYRISK, slope, soil erodibility, and a factor representing the likely increase in soil wetness due to removal of the vegetation. Sedimentation risk was a simple function of stream gradient. Composite surface erosion and sedimentation risk indices were calculated and compared across the 72 catchments in the study area.When evaluated on a catchment scale, two-thirds of the catchments had relatively little post-fire erosion risk. Steeper catchments with higher fuel loadings typically had the highest post-fire surface erosion risk. These were generally located along the major north-south mountain chains and, to a lesser extent, in west-central Colorado. Sedimentation risks were usually highest in the eastern part of the study area where a higher proportion of streams had lower gradients. While data to validate the predicted erosion and sedimentation risks are lacking, the results appear reasonable and are consistent with our limited field observations. The models and analytic procedures can be readily adapted to other locations and should provide useful tools for planning and management at both the catchment and landscape scale.

Microplastics and polycyclic aromatic hydrocarbons (PAHs) in Xiamen coastal areas: Implications for anthropogenic impacts.

PubMed

Tang, Guowen; Liu, Mengyang; Zhou, Qian; He, Haixia; Chen, Kai; Zhang, Haibo; Hu, Jiahui; Huang, Qinghui; Luo, Yongming; Ke, Hongwei; Chen, Bin; Xu, Xiangrong; Cai, Minggang

2018-09-01

Microplastics and polycyclic aromatic hydrocarbons (PAHs) were investigated to study the influence of human activities and to find their possible relationship on the coastal environments, where the coastal areas around Xiamen are undergoing intensive processes of industrialization and urbanization in the southeast China. The abundance of microplastics in Xiamen coastal areas was 103 to 2017particles/m 3 in surface seawater and 76 to 333 particles/kg in sediments. Concentrations of dissolved PAHs varied from 18.1 to 248ng/L in surface seawater. The abundances of microplastics from the Western Harbor in surface seawater and sediments were higher than those from other areas. Foams were dominated in surface seawater samples, however, no foams were found in sediments samples. The microscope selection and FTIR analysis suggested that polyethylene (PE) and polypropylene (PP) were dominant microplastics. The cluster analysis results demonstrated that fibers and granules had the similar sources, and films had considerably correlation with all types of PAHs (3 or 4-ring PAHs and alkylated PAHs). Plastic film mulch from agriculture practice might be a potential source of microplastics in study areas. Results of our study support that river runoff, watershed area, population and urbanization rate influence the distribution of microplastics in estuarine surface water, and the prevalence of microplastic pollution calls for monitoring microplastics at a national scale. Copyright © 2018 Elsevier B.V. All rights reserved.

Monitoring urban land cover change by updating the national land cover database impervious surface products

USGS Publications Warehouse

Xian, George Z.; Homer, Collin G.

2009-01-01

The U.S. Geological Survey (USGS) National Land Cover Database (NLCD) 2001 is widely used as a baseline for national land cover and impervious conditions. To ensure timely and relevant data, it is important to update this base to a more recent time period. A prototype method was developed to update the land cover and impervious surface by individual Landsat path and row. This method updates NLCD 2001 to a nominal date of 2006 by using both Landsat imagery and data from NLCD 2001 as the baseline. Pairs of Landsat scenes in the same season from both 2001 and 2006 were acquired according to satellite paths and rows and normalized to allow calculation of change vectors between the two dates. Conservative thresholds based on Anderson Level I land cover classes were used to segregate the change vectors and determine areas of change and no-change. Once change areas had been identified, impervious surface was estimated for areas of change by sampling from NLCD 2001 in unchanged areas. Methods were developed and tested across five Landsat path/row study sites that contain a variety of metropolitan areas. Results from the five study areas show that the vast majority of impervious surface changes associated with urban developments were accurately captured and updated. The approach optimizes mapping efficiency and can provide users a flexible method to generate updated impervious surface at national and regional scales.

Regional Climate Implications of Large-scale Cultivation of Biofuel Crops

NASA Astrophysics Data System (ADS)

Rowe, C. M.; Oglesby, R. J.; Hays, C. J.; van Etten, A. R.

2008-12-01

Conversion from corn-based ethanol to cellulosic ethanol has the potential to dramatically alter the production of biofuels in the United States and could result in large-scale changes in the agricultural landscape of vast areas of the country. Regions currently dominated by corn production could see widespread planting of switchgrass and other fast-growing, water-efficient sources of cellulose biomass. An often overlooked side effect of these land-cover changes could be a significant alteration of the energy fluxes between the land surface and the atmosphere with profound local, regional, and continental impacts on the climate system. Changes in the surface energy balance result primarily from differences in the seasonality of transpiration from corn versus switchgrass and could be enhanced as a result of a reduced need for irrigation of switchgrass in areas where corn can be produced only under irrigation. Preliminary modeling results using a simple "bucket" land surface model coupled to the WRF mesoscale model have demonstrated increases in summertime average daily maximum temperature of up to 4° C, smaller increases of up to 2° C in nighttime minimum temperatures and reductions in precipitation by up to 25% when corn was changed to switchgrass over the central United States. Improved parameterization of biofuel crops in more sophisticated land surface models will allow us to refine these preliminary estimates and assess the impacts of large-scale conversion to cellulosic biofuel crops, relative to greenhouse gas induced regional climate change.

Toward irrigation retrieval by combining multi-sensor remote sensing data into a land surface model over a semi-arid region

NASA Astrophysics Data System (ADS)

Malbéteau, Y.; Lopez, O.; Houborg, R.; McCabe, M.

2017-12-01

Agriculture places considerable pressure on water resources, with the relationship between water availability and food production being critical for sustaining population growth. Monitoring water resources is particularly important in arid and semi-arid regions, where irrigation can represent up to 80% of the consumptive uses of water. In this context, it is necessary to optimize on-farm irrigation management by adjusting irrigation to crop water requirements throughout the growing season. However, in situ point measurements are not routinely available over extended areas and may not be representative at the field scale. Remote sensing approaches present as a cost-effective technique for mapping and monitoring broad areas. By taking advantage of multi-sensor remote sensing methodologies, such as those provided by MODIS, Landsat, Sentinel and Cubesats, we propose a new method to estimate irrigation input at pivot-scale. Here we explore the development of crop-water use estimates via these remote sensing data and integrate them into a land surface modeling framework, using a farm in Saudi Arabia as a demonstration of what can be achieved at larger scales.

Ion and laser microprobes applied to the measurement of corrosion produced hydrogen on a microscopic scale.

NASA Technical Reports Server (NTRS)

Gray, H. R.

1972-01-01

Use of an ion microprobe and a laser microprobe to measure concentrations of corrosion-produced hydrogen on a microscopic scale. Hydrogen concentrations of several thousand ppm were measured by both analytical techniques below corroded and fracture surfaces of hot salt stress corroded titanium alloy specimens. This extremely high concentration compares with only about 100 ppm hydrogen determined by standard vacuum fusion chemical analyses of bulk samples. Both the ion and laser microprobes were used to measure hydrogen concentration profiles in stepped intervals to substantial depths below the original corroded and fracture surfaces. For the ion microprobe, the area of local analysis was 22 microns in diameter and for the laser microprobe, the area of local analysis was about 300 microns in diameter. The segregation of hydrogen below fracture surfaces supports a previously proposed theory that corrosion-produced hydrogen is responsible for hot salt stress corrosion embrittlement and cracking of titanium alloys. These advanced analytical techniques suggest great potential for many areas of stress corrosion and hydrogen embrittlement research, quality control, and field inspection of corrosion problems. For example, it appears possible that a contour map of hydrogen distribution at notch roots and crack tips could be quantitatively determined. Such information would be useful in substantiating current theories of stress corrosion and hydrogen embrittlement.

Surficial Geologic Map of the Pocasset-Provincetown-Cuttyhunk-Nantucket 24-Quadrangle Area of Cape Cod and Islands, Southeast Massachusetts

USGS Publications Warehouse

Stone, Byron D.; DiGiacomo-Cohen, Mary L.

2006-01-01

The surficial geologic map layer shows the distribution of nonlithified earth materials at land surface in an area of 24 7.5-minute quadrangles (555 mi2 total) in southeast Massachusetts. Across Massachusetts, these materials range from a few feet to more than 500 ft in thickness. They overlie bedrock, which crops out in upland hills and as resistant ledges in valley areas. On Cape Cod and adjacent islands, these materials completely cover the bedrock surface. The geologic map differentiates surficial materials of Quaternary age on the basis of their lithologic characteristics (such as grain size and sedimentary structures), constructional geomorphic features, stratigraphic relations, and age. Surficial earth materials significantly affect human use of the land, and an accurate description of their distribution is particularly important for assessing water resources, construction aggregate resources, and earth-surface hazards, and for making land-use decisions. This work is part of a comprehensive study to produce a statewide digital map of the surficial geology at a 1:24,000-scale level of accuracy. This report includes explanatory text (PDF), quadrangle maps at 1:24,000 scale (PDF files), GIS data layers (ArcGIS shapefiles), metadata for the GIS layers, scanned topographic base maps (TIF), and a readme.txt file.

Small-scale and mesoscale lake surface water temperature structure: Thermography and in situ measurements from Lake Geneva, Switzerland

NASA Astrophysics Data System (ADS)

Irani Rahaghi, Abolfazl; Lemmin, Ulrich; Bouffard, Damien; Riffler, Michael; Wunderle, Stefan; Barry, Andrew

2017-04-01

Lake surface water temperature (LSWT), which varies spatially and temporarily, reflects meteorological and climatological forcing more than any other physical lake parameter. There are different data sources for LSWT mapping, including remote sensing and in situ measurements. Depending on cloud cover, satellite data can depict large-scale thermal patterns, but not the meso- or small-scale processes. Meso-scale thermography allows complementing (and hence ground-truth) satellite imagery at the sub-pixel scale. A Balloon Launched Imaging and Monitoring Platform (BLIMP) was used to measure the LSWT at the meso-scale. The BLIMP consists of a small balloon tethered to a boat and is equipped with thermal and RGB cameras, as well as other instrumentation for geo-location and communication. A feature matching-based algorithm was implemented to create composite thermal images. Simultaneous ground-truthing of the BLIMP data were achieved using an autonomous craft measuring among other in situ surface/near surface temperatures, radiation and meteorological data. Latent and sensible surface heat fluxes were calculated using the bulk parameterization algorithm based on similarity theory. Results are presented for the day-time stratified low wind speed (up to 3 ms-1) conditions over Lake Geneva for two field campaigns, each of 6 h on 18 March and 19 July 2016. The meso-scale temperature field ( 1-m pixel resolution) had a range and standard deviation of 2.4°C and 0.3°C, respectively, over a 1-km2 area (typical satellite pixel size). Interestingly, at the sub-pixel scale, various temporal and spatial thermal structures are evident - an obvious example being streaks in the along-wind direction during March, which we hypothesize are caused by the steady 3 h wind condition. The results also show that the spatial variability of the estimated total heat flux is due to the corresponding variability of the longwave cooling from the water surface and the latent heat flux.

CO{sub 2} Laser Ablation Propulsion Area Scaling With Polyoxymethylene Propellant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinko, John E.; Ichihashi, Katsuhiro; Ogita, Naoya

The topic of area scaling is of great importance in the laser propulsion field, including applications to removal of space debris and to selection of size ranges for laser propulsion craft in air or vacuum conditions. To address this issue experimentally, a CO{sub 2} laser operating at up to 10 J was used to irradiate targets. Experiments were conducted in air and vacuum conditions over a range of areas from about 0.05-5 cm{sup 2} to ablate flat polyoxymethylene targets at several fluences. Theoretical effects affecting area scaling, such as rarefaction waves, thermal diffusion, and diffraction, are discussed in terms ofmore » the experimental results. Surface profilometry was used to characterize the ablation samples. A CFD model is used to facilitate analysis, and key results are compared between experimental and model considerations. The dependence of key laser propulsion parameters, including the momentum coupling coefficient and specific impulse, are calculated based on experimental data, and results are compared to existing literature data.« less

Fire modeling in the Brazilian arc of deforestation through nested coupling of atmosphere, dynamic vegetation, LUCC and fire spread models

NASA Astrophysics Data System (ADS)

Tourigny, E.; Nobre, C.; Cardoso, M. F.

2012-12-01

Deforestation of tropical forests for logging and agriculture, associated to slash-and-burn practices, is a major source of CO2 emissions, both immediate due to biomass burning and future due to the elimination of a potential CO2 sink. Feedbacks between climate change and LUCC (Land-Use and Land-Cover Change) can potentially increase the loss of tropical forests and increase the rate of CO2 emissions, through mechanisms such as land and soil degradation and the increase in wildfire occurrence and severity. However, current understanding of the processes of fires (including ignition, spread and consequences) in tropical forests and climatic feedbacks are poorly understood and need further research. As the processes of LUCC and associated fires occur at local scales, linking them to large-scale atmospheric processes requires a means of up-scaling higher resolutions processes to lower resolutions. Our approach is to couple models which operate at various spatial and temporal scales: a Global Climate Model (GCM), Dynamic Global Vegetation Model (DGVM) and local-scale LUCC and fire spread model. The climate model resolves large scale atmospheric processes and forcings, which are imposed on the surface DGVM and fed-back to climate. Higher-resolution processes such as deforestation, land use management and associated (as well as natural) fires are resolved at the local level. A dynamic tiling scheme allows to represent local-scale heterogeneity while maintaining computational efficiency of the land surface model, compared to traditional landscape models. Fire behavior is modeled at the regional scale (~500m) to represent the detailed landscape using a semi-empirical fire spread model. The relatively coarse scale (as compared to other fire spread models) is necessary due to the paucity of detailed land-cover information and fire history (particularly in the tropics and developing countries). This work presents initial results of a spatially-explicit fire spread model coupled to the IBIS DGVM model. Our area of study comprises selected regions in and near the Brazilian "arc of deforestation". For model training and evaluation, several areas have been mapped using high-resolution imagery from the Landsat TM/ETM+ sensors (Figure 1). This high resolution reference data is used for local-scale simulations and also to evaluate the accuracy of the global MCD45 burned area product, which will be used in future studies covering the entire "arc of deforestation".; Area of study along the arc of deforestation and cerrado: landsat scenes used and burned area (2010) from MCD45 product.

Investigating scintillometer source areas

NASA Astrophysics Data System (ADS)

Perelet, A. O.; Ward, H. C.; Pardyjak, E.

2017-12-01

Scintillometry is an indirect ground-based method for measuring line-averaged surface heat and moisture fluxes on length scales of 0.5 - 10 km. These length scales are relevant to urban and other complex areas where setting up traditional instrumentation like eddy covariance is logistically difficult. In order to take full advantage of scintillometry, a better understanding of the flux source area is needed. The source area for a scintillometer is typically calculated as a convolution of point sources along the path. A weighting function is then applied along the path to compensate for a total signal contribution that is biased towards the center of the beam path, and decreasing near the beam ends. While this method of calculating the source area provides an estimate of the contribution of the total flux along the beam, there are still questions regarding the physical meaning of the weighted source area. These questions are addressed using data from an idealized experiment near the Salt Lake City International Airport in northern Utah, U.S.A. The site is a flat agricultural area consisting of two different land uses. This simple heterogeneity in the land use facilitates hypothesis testing related to source areas. Measurements were made with a two wavelength scintillometer system spanning 740 m along with three standard open-path infrared gas analyzer-based eddy-covariance stations along the beam path. This configuration allows for direct observations of fluxes along the beam and comparisons to the scintillometer average. The scintillometer system employed measures the refractive index structure parameter of air for two wavelengths of electromagnetic radiation, 880 μm and 1.86 cm to simultaneously estimate path-averaged heat and moisture fluxes, respectively. Meteorological structure parameters (CT2, Cq2, and CTq) as well as surface fluxes are compared for various amounts of source area overlap between eddy covariance and scintillometry. Additionally, surface properties from LANDSAT 7 & 8 are used to help understand source area composition for different times throughout the experiment.

Marine mammal distribution in the open ocean: a comparison of ocean color data products and levant time scales

NASA Astrophysics Data System (ADS)

Ohern, J.

2016-02-01

Marine mammals are generally located in areas of enhanced surface primary productivity, though they may forage much deeper within the water column and higher on the food chain. Numerous studies over the past several decades have utilized ocean color data from remote sensing instruments (CZCS, MODIS, and others) to asses both the quantity and time scales over which surface primary productivity relates to marine mammal distribution. In areas of sustained upwelling, primary productivity may essentially grow in the secondary levels of productivity (the zooplankton and nektonic species on which marine mammals forage). However, in many open ocean habitats a simple trophic cascade does not explain relatively short time lags between enhanced surface productivity and marine mammal presence. Other dynamic features that entrain prey or attract marine mammals may be responsible for the correlations between marine mammals and ocean color. In order to investigate these features, two MODIS (moderate imaging spectroradiometer) data products, the concentration as well as the standard deviation of surface chlorophyll were used in conjunction with marine mammal sightings collected within Ecuadorian waters. Time lags between enhanced surface chlorophyll and marine mammal presence were on the order of 2-4 weeks, however correlations were much stronger when the standard deviation of spatially binned images was used, rather than the chlorophyll concentrations. Time lags also varied between Balaenopterid and Odontocete cetaceans. Overall, the standard deviation of surface chlorophyll proved a useful tool for assessing potential relationships between marine mammal sightings and surface chlorophyll.

Mapping Hydrophobicity on the Protein Molecular Surface at Atom-Level Resolution

PubMed Central

Nicolau Jr., Dan V.; Paszek, Ewa; Fulga, Florin; Nicolau, Dan V.

2014-01-01

A precise representation of the spatial distribution of hydrophobicity, hydrophilicity and charges on the molecular surface of proteins is critical for the understanding of the interaction with small molecules and larger systems. The representation of hydrophobicity is rarely done at atom-level, as this property is generally assigned to residues. A new methodology for the derivation of atomic hydrophobicity from any amino acid-based hydrophobicity scale was used to derive 8 sets of atomic hydrophobicities, one of which was used to generate the molecular surfaces for 35 proteins with convex structures, 5 of which, i.e., lysozyme, ribonuclease, hemoglobin, albumin and IgG, have been analyzed in more detail. Sets of the molecular surfaces of the model proteins have been constructed using spherical probes with increasingly large radii, from 1.4 to 20 Å, followed by the quantification of (i) the surface hydrophobicity; (ii) their respective molecular surface areas, i.e., total, hydrophilic and hydrophobic area; and (iii) their relative densities, i.e., divided by the total molecular area; or specific densities, i.e., divided by property-specific area. Compared with the amino acid-based formalism, the atom-level description reveals molecular surfaces which (i) present an approximately two times more hydrophilic areas; with (ii) less extended, but between 2 to 5 times more intense hydrophilic patches; and (iii) 3 to 20 times more extended hydrophobic areas. The hydrophobic areas are also approximately 2 times more hydrophobicity-intense. This, more pronounced “leopard skin”-like, design of the protein molecular surface has been confirmed by comparing the results for a restricted set of homologous proteins, i.e., hemoglobins diverging by only one residue (Trp37). These results suggest that the representation of hydrophobicity on the protein molecular surfaces at atom-level resolution, coupled with the probing of the molecular surface at different geometric resolutions, can capture processes that are otherwise obscured to the amino acid-based formalism. PMID:25462574

[Evolution pattern of impervious surface in the Yuqiao Reservoir Watershed, Tianjin, China during the process of urbanization.

PubMed

Xie, Hui Jun; Li, Chong Wei; Zhang, Ya Juan; Song, Ai Yun

2016-04-22

Imperviousness in watershed is a key index to measure urbanization status which exerts an important impact on both eco-hydrological process and spatio-temporal pattern. Taking Yuqiao Reservoir Watershed as a case study area, based on the ENVI 5.1 software, the basic impervious surface information was extracted from remote sensing images taken in 1984, 1994, 2004 and 2013. The linear spectral mixture analysis (LSMA) model was applied to extract the impervious surface area (ISA) in nine coverage classes of watershed in order to analyze its spatio-temporal varying trend in terms of the landscape pattern metrics. Results showed that the RMSE and IS pixel accuracy of all samples were 0.005 and 85.4% respectively, which indicated that the method of extracting impervious surface on a basin scale was feasible. The average of ISA showed a linear growth, from 0.16 to 0.23, the impervious surface area increased by 4.9% in the whole watershed, and the total impervious surface area increased by 1 time. In the sub-basin road network, the impervious surface area increased gradually with the density of the road network, and its expansion pattern was of infilling growth. The patch shape of the middle coverage degree was irregular, and its fragmentation degree was the highest. The fragmentation degree and diversity of the landscape in the whole river basin increased year by year due to increasing human disturbance.

Vegetation Coverage and Impervious Surface Area Estimated Based on the Estarfm Model and Remote Sensing Monitoring

NASA Astrophysics Data System (ADS)

Hu, Rongming; Wang, Shu; Guo, Jiao; Guo, Liankun

2018-04-01

Impervious surface area and vegetation coverage are important biophysical indicators of urban surface features which can be derived from medium-resolution images. However, remote sensing data obtained by a single sensor are easily affected by many factors such as weather conditions, and the spatial and temporal resolution can not meet the needs for soil erosion estimation. Therefore, the integrated multi-source remote sensing data are needed to carry out high spatio-temporal resolution vegetation coverage estimation. Two spatial and temporal vegetation coverage data and impervious data were obtained from MODIS and Landsat 8 remote sensing images. Based on the Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model (ESTARFM), the vegetation coverage data of two scales were fused and the data of vegetation coverage fusion (ESTARFM FVC) and impervious layer with high spatiotemporal resolution (30 m, 8 day) were obtained. On this basis, the spatial variability of the seepage-free surface and the vegetation cover landscape in the study area was measured by means of statistics and spatial autocorrelation analysis. The results showed that: 1) ESTARFM FVC and impermeable surface have higher accuracy and can characterize the characteristics of the biophysical components covered by the earth's surface; 2) The average impervious surface proportion and the spatial configuration of each area are different, which are affected by natural conditions and urbanization. In the urban area of Xi'an, which has typical characteristics of spontaneous urbanization, landscapes are fragmented and have less spatial dependence.

Monitoring and validating spatio-temporal continuously daily evapotranspiration and its components at river basin scale

NASA Astrophysics Data System (ADS)

Song, L.; Liu, S.; Kustas, W. P.; Nieto, H.

2017-12-01

Operational estimation of spatio-temporal continuously daily evapotranspiration (ET), and the components evaporation (E) and transpiration (T), at watershed scale is very useful for developing a sustainable water resource strategy in semi-arid and arid areas. In this study, multi-year all-weather daily ET, E and T were estimated using MODIS-based (Dual Temperature Difference) DTD model under different land covers in Heihe watershed, China. The remotely sensed ET was validated using ground measurements from large aperture scintillometer systems, with a source area of several kilometers, under grassland, cropland and riparian shrub-forest. The results showed that the remotely sensed ET produced mean absolute percent deviation (MAPD) errors of about 30% during the growing season for all-weather conditions, but the model performed better under clear sky conditions. However, uncertainty in interpolated MODIS land surface temperature input data under cloudy conditions to the DTD model, and the representativeness of LAS measurements for the heterogeneous land surfaces contribute to the discrepancies between the modeled and ground measured surface heat fluxes, especially for the more humid grassland and heterogeneous shrub-forest sites.

Hg localisation in Tillandsia usneoides L. (Bromeliaceae), an atmospheric biomonitor

NASA Astrophysics Data System (ADS)

Amado Filho, G. M.; Andrade, L. R.; Farina, M.; Malm, O.

The Spanish moss, Tillandsia usneoides, has been applied as an atmospheric biomonitor of Hg contamination, although the mechanism of metal plant accumulation has not been understood until now. In the present work, analytical scanning electron microscopy (SEM) was used to localize Hg in T. usneoides exposed to a Hg-air-contaminated area during 15 days. After this period, Hg was determined by the flow injection mercury system, and plants were prepared for SEM observation and energy-dispersive X-ray analysis. A concentration of 2702±318 μg Hg g -1 was determined in exposed plants. The presented microanalytical results demonstrated that Hg was partly associated with atmospheric particles deposited upon the plant surface, but it was highly absorbed by the scales, stem and leaves surfaces and less absorbed by epidermal cells of T. usneoides. No Hg was detected in mesophyll parenchyma or in vascular system cells. The great surface adsorption area provided by the scales, in addition to the characteristics of T. usneoides morphology, especially of the node region, are suggested to confer the great capability of T. usneoides in Hg holding.

Pond fractals in a tidal flat.

PubMed

Cael, B B; Lambert, Bennett; Bisson, Kelsey

2015-11-01

Studies over the past decade have reported power-law distributions for the areas of terrestrial lakes and Arctic melt ponds, as well as fractal relationships between their areas and coastlines. Here we report similar fractal structure of ponds in a tidal flat, thereby extending the spatial and temporal scales on which such phenomena have been observed in geophysical systems. Images taken during low tide of a tidal flat in Damariscotta, Maine, reveal a well-resolved power-law distribution of pond sizes over three orders of magnitude with a consistent fractal area-perimeter relationship. The data are consistent with the predictions of percolation theory for unscreened perimeters and scale-free cluster size distributions and are robust to alterations of the image processing procedure. The small spatial and temporal scales of these data suggest this easily observable system may serve as a useful model for investigating the evolution of pond geometries, while emphasizing the generality of fractal behavior in geophysical surfaces.

Pond fractals in a tidal flat

NASA Astrophysics Data System (ADS)

Cael, B. B.; Lambert, Bennett; Bisson, Kelsey

2015-11-01

Studies over the past decade have reported power-law distributions for the areas of terrestrial lakes and Arctic melt ponds, as well as fractal relationships between their areas and coastlines. Here we report similar fractal structure of ponds in a tidal flat, thereby extending the spatial and temporal scales on which such phenomena have been observed in geophysical systems. Images taken during low tide of a tidal flat in Damariscotta, Maine, reveal a well-resolved power-law distribution of pond sizes over three orders of magnitude with a consistent fractal area-perimeter relationship. The data are consistent with the predictions of percolation theory for unscreened perimeters and scale-free cluster size distributions and are robust to alterations of the image processing procedure. The small spatial and temporal scales of these data suggest this easily observable system may serve as a useful model for investigating the evolution of pond geometries, while emphasizing the generality of fractal behavior in geophysical surfaces.

Influence of hydrophobic and superhydrophobic surfaces on reducing aerodynamic insect residues

NASA Astrophysics Data System (ADS)

Krishnan, K. Ghokulla; Milionis, Athanasios; Loth, Eric; Farrell, Thomas E.; Crouch, Jeffrey D.; Berry, Douglas H.

2017-01-01

Insect fouling during takeoff, climb and landing can result in increased drag and fuel consumption for aircrafts with laminar-flow surfaces. This study investigates the effectiveness of various hydrophobic and superhydrophobic surfaces in reducing residue of insects on an aerodynamic surface at relatively high impact speeds (about 45 m/s). An experimental setup consisting of a wind tunnel and a method to inject live flightless fruit flies was used to test the effectiveness of various surfaces against insect fouling. Insect fouling was analyzed based on residue area and height from multiple impacts. In general most of the residue area was due to the hemolymph spreading while most of the residue height was due to adhesion of exoskeleton parts. Hydrophobic and especially superhydrophobic surfaces performed better than a hydrophilic aluminum surface in terms of minimizing the residue area of various insect components (exoskeleton, hemolymph, and red fluid). Surfaces with reduced wettability and short lateral length scales tended to have the smallest residue area. Residue height was not as strongly influenced by surface wettability since even a single exoskeleton adhered to the surface upon impact was enough to produce a residue height of the order of one mm. In general, the results indicate that hemolymph spread needs to be avoided (e.g. by having reduced wettability and short lateral correlation lengths) in order to minimize the residue area, while exoskeleton adherence needs to be avoided (e.g. by having oleophobic properties and micro/nano roughness) in order to minimize the residue height. In particular, two of the superhydrophobic coatings produced substantial reduction in residue height and area, relative to the baseline surface of aluminum. However, the surfaces also showed poor mechanical durability on the high-speed insect impact location. This suggests that although low wettability materials show great insect anti-fouling behavior, their durability needs to be substantially improved in order to withstand harsh aerospace conditions.

Nanoconfinement platform for nanostructure quantification via grazing-transmission X-ray scattering

DOEpatents

Black, Charles T.; Yager, Kevin G.

2017-01-31

A nano-confinement platform that may allow improved quantification of the structural order of nanometer-scale systems. Sample-holder `chips` are designed for the GTSAXS experimental geometry. The platform involves fabricated nanostructured sample holders on and in one or more corners of a substrate support where the sample material of interest is positioned at the corner of the substrate support. In an embodiment, the substrate material making up the substrate support beneath the sample-holding area is removed. A scattering x-ray sample platform includes a substrate support arranged in a parallelepiped form, having a substantially flat base and a substantially flat top surface, the top surface being substantially parallel with the base, the parallelepiped having a plurality of corners. At least one corner of the substrate support has a sample holding area formed in the top surface of the substrate support and within a predetermined distance from the corner. The sample holding area includes a regular array of nano-wells formed in the top surface of the substrate support.

A scanning tunneling microscope with a scanning range from hundreds of micrometers down to nanometer resolution.

PubMed

Kalkan, Fatih; Zaum, Christopher; Morgenstern, Karina

2012-10-01

A beetle type stage and a flexure scanning stage are combined to form a two stages scanning tunneling microscope (STM). It operates at room temperature in ultrahigh vacuum and is capable of scanning areas up to 300 μm × 450 μm down to resolution on the nanometer scale. This multi-scale STM has been designed and constructed in order to investigate prestructured metallic or semiconducting micro- and nano-structures in real space from atomic-sized structures up to the large-scale environment. The principle of the instrument is demonstrated on two different systems. Gallium nitride based micropillars demonstrate scan areas up to hundreds of micrometers; a Au(111) surface demonstrates nanometer resolution.

Location of Viking 1 Lander on the surface of Mars

USGS Publications Warehouse

Morris, E.C.; Jones, K.L.; Berger, J.P.

1978-01-01

A location of the Viking 1 Lander on the surface of Mars has been determined by correlating topographic features in the lander pictures with similar features in the Viking orbiter pictures. Radio tracking data narrowed the area of search for correlating orbiter and lander features and an area was found on the orbiter pictures in which there is good agreement with topographic features on the lander pictures. This location, when plotted on the 1:250,000 scale photomosaic of the Yorktown Region of Mars (U.S. Geological Survey, 1977) is at 22.487??N latitude and 48.041??W longitude. ?? 1978.

Exploration for fossil and nuclear fuels from orbital altitudes

NASA Technical Reports Server (NTRS)

Short, N. M.

1975-01-01

A review of satellite-based photographic (optical and infrared) and microwave exploration and large-area mapping of the earth's surface in the ERTS program. Synoptic cloud-free coverage of large areas has been achieved with planimetric vertical views of the earth's surface useful in compiling close-to-orthographic mosaics. Radar penetration of cloud cover and infrared penetration of forest cover have been successful to some extent. Geological applications include map editing (with corrections in scale and computer processing of images), landforms analysis, structural geology studies, lithological identification, and exploration for minerals and fuels. Limitations of the method are noted.

Characterizing the fabric of the urban environment: A case studyof Metropolitan Chicago, Illinois and Executive Summary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akbari, Hashem; Rose, Leanna Shea

2001-10-30

Urban fabric data are needed in order to estimate the impactof light-colored surfaces (roofs and pavements) and urban vegetation(trees, grass, shrubs) on the meteorology and air quality of a city, andto design effective implementation programs. In this report, we discussthe result of a semi-automatic Monte-Carlo statistical approach used todevelop data on surface-type distribution and city-fabric makeup(percentage of various surface-types) using aerial colororthophotography. The digital aerial photographs for metropolitan Chicagocovered a total of about 36 km2 (14 mi2). At 0.3m resolution, there wereapproximately 3.9 x 108 pixels of data. Four major land-use types wereexamined: commercial, industrial, residential, andtransportation/communication. On average, formore » the areas studied, atground level vegetation covers about 29 percent of the area (ranging 4 80percent); roofs cover about 25 percent (ranging 8 41 percent), and pavedsurfaces about 33 percent (ranging 12 59 percent). For the most part,trees shade streets, parking lots, grass, and side-walks. In commercialareas, paved surfaces cover 50 60 percent of the area. In residentialareas, on average, paved surfaces cover about 27percent of the area.Land-use/land-cover (LULC) data from the United States Geological Surveywas used to extrapolate these results from neighborhood scales tometropolitan Chicago. In an area of roughly 2500 km2, defining most ofmetropolitan Chicago, over 53 percent is residential. The total roof areais about 680 km2, and the total paved surfaces (roads, parking areas,sidewalks) are about 880 km2. The total vegetated area is about 680km2.« less

Landscape genetic analyses reveal fine-scale effects of forest fragmentation in an insular tropical bird.

PubMed

Khimoun, Aurélie; Peterman, William; Eraud, Cyril; Faivre, Bruno; Navarro, Nicolas; Garnier, Stéphane

2017-10-01

Within the framework of landscape genetics, resistance surface modelling is particularly relevant to explicitly test competing hypotheses about landscape effects on gene flow. To investigate how fragmentation of tropical forest affects population connectivity in a forest specialist bird species, we optimized resistance surfaces without a priori specification, using least-cost (LCP) or resistance (IBR) distances. We implemented a two-step procedure in order (i) to objectively define the landscape thematic resolution (level of detail in classification scheme to describe landscape variables) and spatial extent (area within the landscape boundaries) and then (ii) to test the relative role of several landscape features (elevation, roads, land cover) in genetic differentiation in the Plumbeous Warbler (Setophaga plumbea). We detected a small-scale reduction of gene flow mainly driven by land cover, with a negative impact of the nonforest matrix on landscape functional connectivity. However, matrix components did not equally constrain gene flow, as their conductivity increased with increasing structural similarity with forest habitat: urban areas and meadows had the highest resistance values whereas agricultural areas had intermediate resistance values. Our results revealed a higher performance of IBR compared to LCP in explaining gene flow, reflecting suboptimal movements across this human-modified landscape, challenging the common use of LCP to design habitat corridors and advocating for a broader use of circuit theory modelling. Finally, our results emphasize the need for an objective definition of landscape scales (landscape extent and thematic resolution) and highlight potential pitfalls associated with parameterization of resistance surfaces. © 2017 John Wiley & Sons Ltd.

Modeling evapotranspiration over China's landmass from 1979-2012 using three surface models

NASA Astrophysics Data System (ADS)

Sun, Shaobo; Chen, Baozhang; Zhang, Huifang; Lin, Xiaofeng

2017-04-01

Land surface models (LSMs) are useful tools to estimate land evapotranspiration at a grid scale and for a long-term applications. Here, the Community Land Model 4.0 (CLM4.0), Dynamic Land Model (DLM) and Variable Infiltration Capacity (VIC) model were driven with observation-based forcing data sets, and a multiple LSM ensemble-averaged evapotranspiration (ET) product (LSMs-ET) was developed and its spatial-temporal variations were analyzed for the China landmass over the period 1979-2012. Evaluations against measurements from nine flux towers at site scale and surface water budget based ET at regional scale showed that the LSMs-ET had good performance in most areas of China's landmass. The inter-comparisons between the ET estimates and the independent ET products from remote sensing and upscaling methods suggested that there were a fairly consistent patterns between each data sets. The LSMs-ET produced a mean annual ET of 351.24±10.7 mm yr-1 over 1979-2012, and its spatial-temporal variation analyses showed that (i) there was an overall significant ET increasing trend, with a value of 0.72 mm yr-1 (p < 0.01); (ii) 36.01% of Chinese land had significant increasing trends, ranging from 1 to 9 mm yr-1, while only 6.41% of the area showed significant decreasing trends, ranging from -6.28 to -0.08 mm yr-1. Analyses of ET variations in each climate region clearly showed that the Tibetan Plateau areas were the main contributors to the overall increasing ET trends of China.

Spatial zonation limits magnesite dissolution in porous media

NASA Astrophysics Data System (ADS)

Li, Li; Salehikhoo, Fatemeh; Brantley, Susan L.; Heidari, Peyman

2014-02-01

We investigate how mineral spatial distribution in porous media affects their dissolution rates. Specifically, we measure the dissolution rate of magnesite interspersed in different patterns in packed columns of quartz sand where the magnesite concentration (v/v) was held constant. The largest difference was observed between a “Mixed column” containing uniformly distributed magnesite and a “One-zone column” containing magnesite packed into one cylindrical center zone aligned parallel to the main flow of acidic inlet fluid (flow-parallel One-zone column). The columns were flushed with acid water at a pH of 4.0 at flow velocities of 3.6 or 0.36 m/d. Breakthrough data show that the rate of magnesite dissolution is 1.6-2 times slower in the One-zone column compared to the Mixed column. This extent of rate limitation is much larger than what was observed in our previous work (14%) for a similar One-zone column where the magnesite was packed in a layer aligned perpendicular to flow (flow-transverse One-zone column). Two-dimensional reactive transport modeling with CrunchFlow revealed that ion activity product (IAP) and local dissolution rates at the grid block scale (0.1 cm) vary by orders of magnitude. Much of the central magnesite zone in the One-zone flow-parallel column is characterized by close or equal to equilibrium conditions with IAP/Keq > 0.1. Two important surface areas are defined to understand the observed rates: the effective surface area (Ae) reflects the magnesite that effectively dissolves under far from equilibrium conditions (IAP/Keq < 0.1), while the interface surface area (AI) reflects the effective magnesite surface that lies along the quartz-magnesite interface. Modeling results reveal that the transverse dispersivity at the interface of the quartz and magnesite zones controls mass transport and therefore the values of Ae and AI. Under the conditions examined in this work, the value of Ae varies from 2% to 67% of the total magnesite BET surface area. Column-scale bulk rates R,B (in units of mol/s) vary linearly with Ae and AI. Using Ae to normalize rates, we calculate a rate constant (10-9.56 mol/m2/s) that is very close to the value of 10-10.0 mol/m2/s under well-mixed conditions at the grid block scale. This implies that the laboratory-field rate discrepancy can potentially be caused by differences in the effective surface area. If we know the effective surface area of dissolution, we will be able to use the rate constant measured in laboratory systems to calculate field rates for some systems. In this work, approximately 60-70% of the Ae is at the magnesite-quartz interface. This implies that in some field systems where the detailed information that we have for our columns is not available, the effective mineral surface area may be approximated by the area of grains residing at the interface of reactive mineral zones. Although it has long been known that spatial heterogeneities play a significant role in determining physical processes such as flow and solute transport, our data are the first that systematically and experimentally quantifies the importance of mineral spatial distribution (chemical heterogeneity) on dissolution.

Morphological Properties of Siloxane-Hydrogel Contact Lens Surfaces.

PubMed

Stach, Sebastian; Ţălu, Ştefan; Trabattoni, Silvia; Tavazzi, Silvia; Głuchaczka, Alicja; Siek, Patrycja; Zając, Joanna; Giovanzana, Stefano

2017-04-01

The aim of this study was to quantitatively characterize the micromorphology of contact lens (CL) surfaces using atomic force microscopy (AFM) and multifractal analysis. AFM and multifractal analysis were used to characterize the topography of new and worn siloxane-hydrogel CLs made of Filcon V (I FDA group). CL surface roughness was studied by AFM in intermittent-contact mode, in air, on square areas of 25 and 100 μm 2 , by using a Nanoscope V MultiMode (Bruker). Detailed surface characterization of the surface topography was obtained using statistical parameters of 3-D (three-dimensional) surface roughness, in accordance with ISO 25178-2: 2012. Before wear, the surface was found to be characterized by out-of-plane and sharp structures, whilst after a wear of 8 h, two typical morphologies were observed. One morphology (sharp type) has a similar aspect as the unworn CLs and the other morphology (smooth type) is characterized by troughs and bumpy structures. The analysis of the AFM images revealed a multifractal geometry. The generalized dimension D q and the singularity spectrum f(α) provided quantitative values that characterize the local scale properties of CL surface geometry at nanometer scale. Surface statistical parameters deduced by multifractal analysis can be used to assess the CL micromorphology and can be used by manufacturers in developing CLs with improved surface characteristics. These parameters can also be used in understanding the tribological interactions of the back surface of the CL with the corneal surface and the front surface of the CL with the under-surface of the eyelid (friction, wear, and micro-elastohydrodynamic lubrication at a nanometer scale).

Moisture harvesting and water transport through specialized micro-structures on the integument of lizards.

PubMed

Comanns, Philipp; Effertz, Christian; Hischen, Florian; Staudt, Konrad; Böhme, Wolfgang; Baumgartner, Werner

2011-01-01

Several lizard species that live in arid areas have developed special abilities to collect water with their bodies' surfaces and to ingest the so collected moisture. This is called rain- or moisture-harvesting. The water can originate from air humidity, fog, dew, rain or even from humid soil. The integument (i.e., the skin plus skin derivatives such as scales) has developed features so that the water spreads and is soaked into a capillary system in between the reptiles' scales. Within this capillary system the water is transported to the mouth where it is ingested. We have investigated three different lizard species which have developed the ability for moisture harvesting independently, viz. the Australian thorny devil (Moloch horridus), the Arabian toadhead agama (Phrynocephalus arabicus) and the Texas horned lizard (Phrynosoma cornutum). All three lizards have a honeycomb like micro ornamentation on the outer surface of the scales and a complex capillary system in between the scales. By investigation of individual scales and by producing and characterising polymer replicas of the reptiles' integuments, we found that the honeycomb like structures render the surface superhydrophilic, most likely by holding a water film physically stable. Furthermore, the condensation of air humidity is improved on this surface by about 100% in comparison to unstructured surfaces. This allows the animals to collect moisture with their entire body surface. The collected water is transported into the capillary system. For Phrynosoma cornutum we found the interesting effect that, in contrast to the other two investigated species, the water flow in the capillary system is not uniform but directed to the mouth. Taken together we found that the micro ornamentation yields a superhydrophilic surface, and the semi-tubular capillaries allow for an efficient passive - and for Phrynosoma directed - transport of water.

Spaceborne imaging radar - Geologic and oceanographic applications

NASA Technical Reports Server (NTRS)

Elachi, C.

1980-01-01

Synoptic, large-area radar images of the earth's land and ocean surface, obtained from the Seasat orbiting spacecraft, show the potential for geologic mapping and for monitoring of ocean surface patterns. Structural and topographic features such as lineaments, anticlines, folds and domes, drainage patterns, stratification, and roughness units can be mapped. Ocean surface waves, internal waves, current boundaries, and large-scale eddies have been observed in numerous images taken by the Seasat imaging radar. This article gives an illustrated overview of these applications.

Functional connectivity in replicated urban landscapes in the land snail (Cornu aspersum).

PubMed

Balbi, Manon; Ernoult, Aude; Poli, Pedro; Madec, Luc; Guiller, Annie; Martin, Marie-Claire; Nabucet, Jean; Beaujouan, Véronique; Petit, Eric J

2018-03-01

Urban areas are highly fragmented and thereby exert strong constraints on individual dispersal. Despite this, some species manage to persist in urban areas, such as the garden snail, Cornu aspersum, which is common in cityscapes despite its low mobility. Using landscape genetic approaches, we combined study area replication and multiscale analysis to determine how landscape composition, configuration and connectivity influence snail dispersal across urban areas. At the overall landscape scale, areas with a high percentage of roads decreased genetic differentiation between populations. At the population scale, genetic differentiation was positively linked with building surface, the proportion of borders where wooded patches and roads appeared side by side and the proportion of borders combining wooded patches and other impervious areas. Analyses based on pairwise genetic distances validated the isolation-by-distance and isolation-by-resistance models for this land snail, with an equal fit to least-cost paths and circuit-theory-based models. Each of the 12 landscapes analysed separately yielded specific relations to environmental features, whereas analyses integrating all replicates highlighted general common effects. Our results suggest that urban transport infrastructures facilitate passive snail dispersal. At a local scale, corresponding to active dispersal, unfavourable habitats (wooded and impervious areas) isolate populations. This work upholds the use of replicated landscapes to increase the generalizability of landscape genetics results and shows how multiscale analyses provide insight into scale-dependent processes. © 2018 John Wiley & Sons Ltd.

Recruitment from an egg bank into the plankton in Baisha Bay, a mariculture base in Southern China

NASA Astrophysics Data System (ADS)

Wang, Qing; Luan, Lei-Lei; Chen, Liang-Dong; Yuan, Dan-Ni; Liu, Sheng; Hwang, Jiang-Shiou; Yang, Yu-Feng

2016-11-01

The potential recruitment of resting eggs of calanoid copepods and rotifers to planktonic populations was investigated in the surface and sub-surface sediments of three mariculture zones: an integrated seaweed Gracilaria lemaneiformis and shellfish cultivation area (G), a fish cultivation area (F), and a shellfish cultivation area (S), as well as the sediments of a nearby control sea area (C) in a mariculture base in Southern China. The potential recruitment of copepod and rotifer eggs in the sediments of C and G was significantly higher than in F and S. Potential recruitment in the sub-surface sediments of F and S was not observed, suggesting that fish and shellfish mariculture may be responsible for this decrease. The hatching success of resting eggs of copepods and rotifers was affected by mariculture type, and that large-scale seaweed cultivation may offset the adverse effect of fish and shellfish cultivation on the resting eggs if integrated cultivation is adopted.

Influence of impurities and contact scale on the lubricating properties of bovine submaxillary mucin (BSM) films on a hydrophobic surface.

PubMed

Nikogeorgos, Nikolaos; Madsen, Jan Busk; Lee, Seunghwan

2014-10-01

Lubricating properties of bovine submaxillary mucin (BSM) on a compliant, hydrophobic surface were studied as influenced by impurities, in particular bovine serum albumin (BSA), at macro and nanoscale contacts by means of pin-on-disk tribometry and friction force microscopy (FFM), respectively. At both contact scales, the purity of BSM and the presence of BSA were quantitatively discriminated. The presence of BSA was responsible for higher frictional forces observed from BSM samples containing relatively larger amount of BSA. But, the mechanisms contributing to higher friction forces by BSA were different at different contact scales. At the macroscale contact, higher friction forces were caused by faster and dominant adsorption of BSA into the contacting area under a continuous cycle of desorption and re-adsorption of the macromolecules from tribostress. Nevertheless, all BSMs lowered the interfacial friction forces due to large contact area and a large number of BSM molecules in the contact area. At the nanoscale contact, however, no significant desorption of the macromolecules is expected in tribological contacts because of too small contact area and extremely small number of BSM molecules involved in the contact area. Instead, increasingly higher friction forces with increasing amount of BSA in BSM layer are attributed to higher viscosity caused by BSA in the layer. Comparable size of AFM probes with BSM molecules allowed them to penetrate through the BSM layers and to scratch on the underlying substrates, and thus induced higher friction forces compared to the sliding contact on bare substrates. Copyright © 2014 Elsevier B.V. All rights reserved.

Understanding Climate Variability of Urban Ecosystems Through the Lens of Citizen Science

NASA Astrophysics Data System (ADS)

Ripplinger, J.; Jenerette, D.; Wang, J.; Chandler, M.; Ge, C.; Koutzoukis, S.

2017-12-01

The Los Angeles megacity is vulnerable to climate warming - a process that locally exacerbates the urban heat island effect as it intensifies with size and density of the built-up area. We know that large-scale drivers play a role, but in order to understand local-scale climate variation, more research is needed on the biophysical and sociocultural processes driving the urban climate system. In this study, we work with citizen scientists to deploy a high-density network of microsensors across a climate gradient to characterize geographic variation in neighborhood meso- and micro-climates. This research asks: How do urbanization, global climate, and vegetation interact across multiple scales to affect local-scale experiences of temperature? Additionally, citizen scientist-led efforts generated research questions focused on examining microclimatic differences among yard groundcover types (rock mulch vs. lawn vs. artificial turf) and also on variation in temperature related to tree cover. Combining sensor measurements with Weather Research and Forecasting (WRF) spatial models and satellite-based temperature, we estimate spatially-explicit maps of land surface temperature and air temperature to illustrate the substantial difference between surface and air urban heat island intensities and the variable degree of coupling between land surface and air temperature in urban areas. Our results show a strong coupling between air temperature variation and landcover for neighborhoods, with significant detectable signatures from tree cover and impervious surface. Temperature covaried most strongly with urbanization intensity at nighttime during peak summer season, when daily mean air temperature ranged from 12.8C to 30.4C across all groundcover types. The combined effects of neighborhood geography and vegetation determine where and how temperature and tree canopy vary within a city. This citizen science-enabled research shows how large-scale climate drivers and urbanization intensity jointly influence the nature and magnitude of coupling between air temperature and tree cover, and demonstrate how urban vegetation provides an important ecosystem service in cities by decreasing the intensity of local urban heat islands.

Detecting and analyzing soil phosphorus loss associated with critical source areas using a remote sensing approach.

PubMed

Lou, Hezhen; Yang, Shengtian; Zhao, Changsen; Shi, Liuhua; Wu, Linna; Wang, Yue; Wang, Zhiwei

2016-12-15

The detection of critical source areas (CSAs) is a key step in managing soil phosphorus (P) loss and preventing the long-term eutrophication of water bodies at regional scale. Most related studies, however, focus on a local scale, which prevents a clear understanding of the spatial distribution of CSAs for soil P loss at regional scale. Moreover, the continual, long-term variation in CSAs was scarcely reported. It is impossible to identify the factors driving the variation in CSAs, or to collect land surface information essential for CSAs detection, by merely using the conventional methodologies at regional scale. This study proposes a new regional-scale approach, based on three satellite sensors (ASTER, TM/ETM and MODIS), that were implemented successfully to detect CSAs at regional scale over 15years (2000-2014). The approach incorporated five factors (precipitation, slope, soil erosion, land use, soil total phosphorus) that drive soil P loss from CSAs. Results show that the average area of critical phosphorus source areas (CPSAs) was 15,056km 2 over the 15-year period, and it occupied 13.8% of the total area, with a range varying from 1.2% to 23.0%, in a representative, intensive agricultural area of China. In contrast to previous studies, we found that the locations of CSAs with P loss are spatially variable, and are more dispersed in their distribution over the long term. We also found that precipitation acts as a key driving factor in the variation of CSAs at regional scale. The regional-scale method can provide scientific guidance for managing soil phosphorus loss and preventing the long-term eutrophication of water bodies at regional scale, and shows great potential for exploring factors that drive the variation in CSAs at global scale. Copyright © 2016 Elsevier B.V. All rights reserved.

COMPARISON OF HYDROLOGIC RESPONSES AT DIFFERENT WATERSHED SCALES

EPA Science Inventory

Land surface hydrology controls runoff production and the associated transport of sediments, and a wide variety of anthropogenic organic chemicals, and nutrients from upland landscape areas and hillslopes to streams and other water bodies. Based on interactions between landscape ...

Investigations of Volcanic and Volatile-Driven Processes Northeast of Hellas Basin, Mars

NASA Astrophysics Data System (ADS)

Mest, S. C.; Crown, D. A.; Michalski, J.; Chuang, F. C.; Price Blount, K.; Bleamaster, L. F.

2018-06-01

We are mapping the geologic units and features in three MTM quadrangles northeast of Hellas basin at 1:1M scale. The area displays evidence for volcanism and widespread volatile-related modification of the surface.

The Synergistic Effect of Leukocyte Platelet-Rich Fibrin and Micrometer/Nanometer Surface Texturing on Bone Healing around Immediately Placed Implants: An Experimental Study in Dogs

PubMed Central

Neiva, Rodrigo F.; Gil, Luiz Fernando; Tovar, Nick; Janal, Malvin N.; Marao, Heloisa Fonseca; Pinto, Nelson; Coelho, Paulo G.

2016-01-01

Aims. This study evaluated the effects of L-PRF presence and implant surface texture on bone healing around immediately placed implants. Methods. The first mandibular molars of 8 beagle dogs were bilaterally extracted, and implants (Blossom™, Intra-Lock International, Boca Raton, FL) were placed in the mesial or distal extraction sockets in an interpolated fashion per animal. Two implant surfaces were distributed per sockets: (1) dual acid-etched (DAE, micrometer scale textured) and (2) micrometer/nanometer scale textured (Ossean™ surface). L-PRF (Intraspin system, Intra-Lock International) was placed in a split-mouth design to fill the macrogap between implant and socket walls on one side of the mandible. The contralateral side received implants without L-PRF. A mixed-model ANOVA (at α = 0.05) evaluated the effect of implant surface, presence of L-PRF, and socket position (mesial or distal), individually or in combination on bone area fraction occupancy (BAFO). Results. BAFO values were significantly higher for the Ossean relative to the DAE surface on the larger mesial socket. The presence of L-PRF resulted in higher BAFO. The Ossean surface and L-PRF presence resulted in significantly higher BAFO. Conclusion. L-PRF and the micro-/nanometer scale textured surface resulted in increased bone formation around immediately placed implants. PMID:28042577

Small-scale martian polygonal terrain: Implications for liquid surface water

USGS Publications Warehouse

Seibert, N.M.; Kargel, J.S.

2001-01-01

Images from the Mars Orbiter Camera (MOC) through August 1999 were analyzed for the global distribution of small-scale polygonal terrain not clearly resolved in Viking Orbiter imagery. With very few exceptions, small-scale polygonal terrain occurs at middle to high latitudes of the northern and southern hemisphere in Hesperian-age geologic units. The largest concentration of this terrain occurs in the Utopia basin in close association with scalloped depressions (interpreted as thermokarst) and appears to represent an Amazonia event. The morphology and occurence of small polygonal terrain suggest they are either mud desiccation cracks or ice-wedge polygons. Because the small-scale polygons in Utopia and Argyre Planitiae are associated with other cold-climate permafrost or glacial features, an ice-wedge model is preferred for these areas. Both cracking mechanisms work most effectively in water- or ice-rich finegrained material and may imply the seasonal or episodic existence of liquid water at the surface.

Global small-scale lunar cartography

NASA Technical Reports Server (NTRS)

Lipskiy, Y. N.; Pskovskiy, Y. P.; Rodionova, Z. F.; Shevchenko, V. V.; Chikmachev, V. I.; Volchkova, L. I.

1972-01-01

The primary sources information for compiling this map were the photographs of the visible hemisphere obtained by earth-based observatories, the Luna 3 and Zond 3 pictures, and a small number of Lunar Orbiter pictures. The primary content of the complete lunar map is the surface relief and its tonal characteristics. In preparing the map, particular attention was devoted to the variety of lunar relief forms. The color spectrum of the map was selected not only for the natural coloring of the lunar surface, but also with the objective of achieving maximum expressiveness. A lunar globe to scale 1:10 million was prepared along with the preparation of the map. The scale of the globe, half that of the map, led to some selection and generalization of the relief forms. The globe permits maintaining simultaneously geometric similarity of contours, exact proportions of areas, and identical scales in all directions. The globe was prepared in both the Latin and Russian languages.

The integration of constructed wetlands into a treatment system for airport runoff.

PubMed

Revitt, D M; Worral, P; Brewer, D

2001-01-01

A new surface runoff treatment system has been designed for London Heathrow Airport, which incorporates separate floating constructed wetlands or reedbeds and sub-surface flow constructed wetlands as major pollutant removal systems. The primary requirement of the newly developed treatment system is to control the concentrations of glycols following their use as de-icers and anti-icers within the airport. The ability of reedbeds to contribute to this treatment role was fully tested through pilot scale, on-site experiments over a 2 year period. The average reductions in runoff BOD concentrations achieved by pilot scale surface flow and sub-surface flow reedbeds were 30.9% and 32.9%, respectively. The corresponding average glycol removal efficiencies were 54.2% and 78.3%, following shock dosing inputs. These treatment performances are used to predict the required full scale constructed wetland surface areas needed to attain the desired effluent water quality. The treatment system also incorporates aeration, storage and, combined with reedbed technology, has been designed to reduce a mixed inlet BOD concentration of 240 mg/l to less than 40 mg/l for water temperatures varying between 6 degrees C and 20 degrees C.

The Effect of Furnishing on Perceived Spatial Dimensions and Spaciousness of Interior Space

PubMed Central

von Castell, Christoph; Oberfeld, Daniel; Hecht, Heiko

2014-01-01

Despite the ubiquity of interior space design, there is virtually no scientific research on the influence of furnishing on the perception of interior space. We conducted two experiments in which observers were asked to estimate the spatial dimensions (size of the room dimensions in meters and centimeters) and to judge subjective spaciousness of various rooms. Experiment 1 used true-to-scale model rooms with a square surface area. Furnishing affected both the perceived height and the spaciousness judgments. The furnished room was perceived as higher but less spacious. In Experiment 2, rooms with different square surface areas and constant physical height were presented in virtual reality. Furnishing affected neither the perceived spatial dimensions nor the perceived spaciousness. Possible reasons for this discrepancy, such as the influence of the presentation medium, are discussed. Moreover, our results suggest a compression of perceived height and depth with decreasing surface area of the room. PMID:25409456

The effect of furnishing on perceived spatial dimensions and spaciousness of interior space.

PubMed

von Castell, Christoph; Oberfeld, Daniel; Hecht, Heiko

2014-01-01

Despite the ubiquity of interior space design, there is virtually no scientific research on the influence of furnishing on the perception of interior space. We conducted two experiments in which observers were asked to estimate the spatial dimensions (size of the room dimensions in meters and centimeters) and to judge subjective spaciousness of various rooms. Experiment 1 used true-to-scale model rooms with a square surface area. Furnishing affected both the perceived height and the spaciousness judgments. The furnished room was perceived as higher but less spacious. In Experiment 2, rooms with different square surface areas and constant physical height were presented in virtual reality. Furnishing affected neither the perceived spatial dimensions nor the perceived spaciousness. Possible reasons for this discrepancy, such as the influence of the presentation medium, are discussed. Moreover, our results suggest a compression of perceived height and depth with decreasing surface area of the room.

Dynamic pesticide removal with activated carbon fibers.

PubMed

Martín-Gullón, I; Font, R

2001-02-01

Rapid small-scale minicolumn tests were carried out to simulate the atrazine adsorption in water phase with three pelletized pitch-based activated carbon fibers (ACF) and one commercial granular activated carbon (GAC). Initial atrazine solutions were prepared with pretreated ground water. Minicolumn tests showed that the performance of highly activated carbon fibers (surface area of 1700 m2/g) is around 7 times better than the commercial GAC (with surface area at around 1100 m2/g), whereas carbon fibers with medium activation degree (surface area of 1500 m2/g) had a removal efficiency worse than the commercial carbon. The high removal efficiency of the highly activated ACF is due to the wide-opened microstructure of the material, with an appreciable contribution of the low size mesopores, maintaining at these conditions a fast kinetic adsorption rate rather than a selective adsorbent for micropollutants vs. natural organic matter.

Projected global ground-level ozone impacts on vegetation under different emission and climate scenarios

NASA Astrophysics Data System (ADS)

Sicard, Pierre; Anav, Alessandro; De Marco, Alessandra; Paoletti, Elena

2017-10-01

The impact of ground-level ozone (O3) on vegetation is largely under-investigated at the global scale despite large areas worldwide that are exposed to high surface O3 levels. To explore future potential impacts of O3 on vegetation, we compared historical and projected surface O3 concentrations simulated by six global atmospheric chemistry transport models on the basis of three representative concentration pathways emission scenarios (i.e. RCP2.6, 4.5, 8.5). To assess changes in the potential surface O3 threat to vegetation at the global scale, we used the AOT40 metric. Results point out a significant exceedance of AOT40 in comparison with the recommendations of UNECE for the protection of vegetation. In fact, many areas of the Northern Hemisphere show that AOT40-based critical levels will be exceeded by a factor of at least 10 under RCP8.5. Changes in surface O3 by 2100 worldwide range from about +4-5 ppb in the RCP8.5 scenario to reductions of about 2-10 ppb in the most optimistic scenario, RCP2.6. The risk of O3 injury for vegetation, through the potential O3 impact on photosynthetic assimilation, decreased by 61 and 47 % under RCP2.6 and RCP4.5, respectively, and increased by 70 % under RCP8.5. Key biodiversity areas in southern and northern Asia, central Africa and North America were identified as being at risk from high O3 concentrations.

Spatial structure and scaling of macropores in hydrological process at small catchment scale

NASA Astrophysics Data System (ADS)

Silasari, Rasmiaditya; Broer, Martine; Blöschl, Günter

2013-04-01

During rainfall events, the formation of overland flow can occur under the circumstances of saturation excess and/or infiltration excess. These conditions are affected by the soil moisture state which represents the soil water content in micropores and macropores. Macropores act as pathway for the preferential flows and have been widely studied locally. However, very little is known about their spatial structure and conductivity of macropores and other flow characteristic at the catchment scale. This study will analyze these characteristics to better understand its importance in hydrological processes. The research will be conducted in Petzenkirchen Hydrological Open Air Laboratory (HOAL), a 64 ha catchment located 100 km west of Vienna. The land use is divided between arable land (87%), pasture (5%), forest (6%) and paved surfaces (2%). Video cameras will be installed on an agricultural field to monitor the overland flow pattern during rainfall events. A wireless soil moisture network is also installed within the monitored area. These field data will be combined to analyze the soil moisture state and the responding surface runoff occurrence. The variability of the macropores spatial structure of the observed area (field scale) then will be assessed based on the topography and soil data. Soil characteristics will be supported with laboratory experiments on soil matrix flow to obtain proper definitions of the spatial structure of macropores and its variability. A coupled physically based distributed model of surface and subsurface flow will be used to simulate the variability of macropores spatial structure and its effect on the flow behaviour. This model will be validated by simulating the observed rainfall events. Upscaling from field scale to catchment scale will be done to understand the effect of macropores variability on larger scales by applying spatial stochastic methods. The first phase in this study is the installation and monitoring configuration of video cameras and soil moisture monitoring equipment to obtain the initial data of overland flow occurrence and soil moisture state relationships.

Spatial correlation of shear-wave velocity within San Francisco Bay Sediments

USGS Publications Warehouse

Thompson, E.M.; Baise, L.G.; Kayen, R.E.

2006-01-01

Sediment properties are spatially variable at all scales, and this variability at smaller scales influences high frequency ground motions. We show that surface shear-wave velocity is highly correlated within San Francisco Bay Area sediments using shear-wave velocity measurements from 210 seismic cone penetration tests. We use this correlation to estimate the surface sediment velocity structure using geostatistics. We find that the variance of the estimated shear-wave velocity is reduced using ordinary kriging, and that including this velocity structure in 2D ground motion simulations of a moderate sized earthquake improves the accuracy of the synthetics. Copyright ASCE 2006.

A Theory for the RF Surface Field for Various Metals at the Destructive Breakdown Limit

NASA Astrophysics Data System (ADS)

Wilson, Perry B.

2006-11-01

By destructive breakdown we mean a breakdown event that results in surface melting over a macroscopic area in a high E-field region of an accelerator structure. A plasma forms over the molten area, bombarding the surface with an intense ion current (˜108 A/cm2), equivalent to a pressure of about a thousand Atmospheres. This pressure in turn causes molten copper to migrate away from the iris tip, resulting in measurable changes in the iris shape. The breakdown process can be roughly divided into four stages: (1) the formation of "plasma spots" at field emission sites, each spot leaving a crater-like footprint; (2) crater clustering, and the formation of areas with hundreds of overlapping craters; (3) surface melting in the region of a crater cluster; (4) the process after surface melting that leads to destructive breakdown. The physics underlying each of these stages is developed, and a comparison is made between the theory and experimental evidence whenever possible. The key to preventing breakdown lies in stage (3). A single plasma spot emits a current of several amperes, a portion of which returns to impact the surrounding area with a power density on the order 107 Watt/cm2. This power density is not quite adequate to melt the surrounding surface on a time scale short compared to the rf pulse length. In a crater field, however, the impact areas from multiple plasma spots overlap to provide sufficient power density for surface melting over an area on the order of 0.1 mm2 or more. The key to preventing breakdown is to choose an iris tip material that requires the highest power density (proportional to the square of the rf surface field) for surface melting, taking into account the penetration depth of the impacting electrons. The rf surface field required for surface melting (relative to copper) has been calculated for a large number elementary metals, plus stainless-steel and carbon.

Global Albedo Variations on Mars from Recent MRO/MARCI and Other Space-Based Observations

NASA Astrophysics Data System (ADS)

Bell, J. F., III; Wellington, D. F.

2017-12-01

Dramatic changes in Mars surface albedo have been quantified by telescopic, orbital, and surface-based observations over the last 40 years. These changes provide important inputs for global and mesoscale climate models, enabling characterization of seasonal and secular variations in the distribution of mobile surface materials (dust, sand) in the planet's current climate regime. Much of the modern record of dust storms and albedo changes comes from synoptic-scale global imaging from the Viking Orbiter, Mars Global Surveyor (MGS), Hubble Space Telescope (HST), and Mars Reconnaissance Orbiter (MRO) missions, as well as local-scale observations from long-lived surface platforms like the Spirit and Opportunity rovers. Here we focus on the substantial time history of global-scale images acquired from the MRO Mars Color Imager (MARCI). MARCI is a wide-angle multispectral imager that acquires daily coverage of most of the surface at up to 1 km/pixel. MARCI has been in orbit since 2006, providing six Mars years of continuous surface and atmospheric observations, and building on the nearly five previous Mars years of global-scale imaging from the MGS Mars Orbiter Camera Wide Angle (MOC/WA) imager, which operated from 1997 to 2006. While many of the most significant MARCI-observed changes in the surface albedo are the result of large dust storms, other regions experience seasonal darkening events that repeat with different degrees of annual regularity. Some of these are associated with local dust storms, while for others, frequent surface changes take place with no associated evidence for dust storms, suggesting action by seasonally-variable winds and/or small-scale storms/dust devils too small to resolve. Discrete areas of dramatic surface changes across widely separated regions of Tharsis and in portions of Solis Lacus and Syrtis Major are among the regions where surface changes have been observed without a direct association to specific detectable dust storm events. Deposition following the annual southern summer dusty season plays a significant role in maintaining the cyclic nature of these changes. These and other historical observations also show that major regional or global-scale dust storms produce unique changes that may require several Mars years to reverse.

Application of a fully integrated surface-subsurface physically based flow model for evaluating groundwater recharge from a flash flood event

NASA Astrophysics Data System (ADS)

Pino, Cristian; Herrera, Paulo; Therrien, René

2017-04-01

In many arid regions around the world groundwater recharge occurs during flash floods. This transient spatially and temporally concentrated flood-recharge process takes place through the variably saturated zone between surface and usually the deep groundwater table. These flood events are characterized by rapid and extreme changes in surface flow depth and velocity and soil moisture conditions. Infiltration rates change over time controlled by the hydraulic gradients and the unsaturated hydraulic conductivity at the surface-subsurface interface. Today is a challenge to assess the spatial and temporal distribution of groundwater recharge from flash flood events under real field conditions at different scales in arid areas. We apply an integrated surface-subsurface variably saturated physically-based flow model at the watershed scale to assess the recharge process during and after a flash flood event registered in an arid fluvial valley in Northern Chile. We are able to reproduce reasonably well observed groundwater levels and surface flow discharges during and after the flood with a calibrated model. We also investigate the magnitude and spatio-temporal distribution of recharge and the response of the system to variations of different surface and subsurface parameters, initial soil moisture content and groundwater table depths and surface flow conditions. We demonstrate how an integrated physically based model allows the exploration of different spatial and temporal system states, and that the analysis of the results of the simulations help us to improve our understanding of the recharge processes in similar type of systems that are common to many arid areas around the world.

Do the energy fluxes and surface conductance of boreal coniferous forests in Europe scale with leaf area?

PubMed

Launiainen, Samuli; Katul, Gabriel G; Kolari, Pasi; Lindroth, Anders; Lohila, Annalea; Aurela, Mika; Varlagin, Andrej; Grelle, Achim; Vesala, Timo

2016-12-01

Earth observing systems are now routinely used to infer leaf area index (LAI) given its significance in spatial aggregation of land surface fluxes. Whether LAI is an appropriate scaling parameter for daytime growing season energy budget, surface conductance (G s ), water- and light-use efficiency and surface-atmosphere coupling of European boreal coniferous forests was explored using eddy-covariance (EC) energy and CO 2 fluxes. The observed scaling relations were then explained using a biophysical multilayer soil-vegetation-atmosphere transfer model as well as by a bulk G s representation. The LAI variations significantly alter radiation regime, within-canopy microclimate, sink/source distributions of CO 2 , H 2 O and heat, and forest floor fluxes. The contribution of forest floor to ecosystem-scale energy exchange is shown to decrease asymptotically with increased LAI, as expected. Compared with other energy budget components, dry-canopy evapotranspiration (ET) was reasonably 'conservative' over the studied LAI range 0.5-7.0 m 2 m -2 . Both ET and G s experienced a minimum in the LAI range 1-2 m 2 m -2 caused by opposing nonproportional response of stomatally controlled transpiration and 'free' forest floor evaporation to changes in canopy density. The young forests had strongest coupling with the atmosphere while stomatal control of energy partitioning was strongest in relatively sparse (LAI ~2 m 2 m -2 ) pine stands growing on mineral soils. The data analysis and model results suggest that LAI may be an effective scaling parameter for net radiation and its partitioning but only in sparse stands (LAI <3 m 2 m -2 ). This finding emphasizes the significance of stand-replacing disturbances on the controls of surface energy exchange. In denser forests, any LAI dependency varies with physiological traits such as light-saturated water-use efficiency. The results suggest that incorporating species traits and site conditions are necessary when LAI is used in upscaling energy exchanges of boreal coniferous forests. © 2016 John Wiley & Sons Ltd.

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Novel Route to Fabrication of Metal-Sandwiched Nanoscale Tapered Structures

NASA Astrophysics Data System (ADS)

Zhang, Yang; Yu, Da-Peng

2009-08-01

Tapered dielectric structures in metal have exhibited extraordinary performance in both surface plasmon polariton (SPP) waveguiding and SPP focusing. This is crucial to plasmonic research and industrial plasmonic device integration. We present a method that facilitates easy fabrication of smooth-surfaced sub-micron tapered structures in large scale simply with electron beam lithography (EBL). When a PMMA layer is spin-coated on previously-EBL-defined PMMA structures, steep edges can be transformed into a declining slope to form tapered PMMA structures, scaled from 10 nm to 1000 nm. Despite the simplicity of our method, patterns with PMMA surface smoothness can be well-positioned and replicated in large numbers, which therefore gives scientists easy access to research on the properties of tapered structures.

Shallowing-upward cyclic patterns within larger-scale transgressive-regressive (T-R) sedimentary sequences, St. Peter through Decorah Formations, Ordovician, Iowa area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witzke, B.J.

1993-03-01

Four large-scale (2--8 Ma) T-R sedimentary sequences of M. Ord. age (late Chaz.-Sherm.) were delimited by Witzke Kolata (1980) in the Iowa area, each bounded by local to regional unconformity/disconformity surfaces. These encompass both siliciclastic and carbonate intervals, in ascending order: (1) St. Peter-Glenwood fms., (2) Platteville Fm., (3) Decorah Fm., (4) Dunleith/upper Decorah fms. Finer-scale resolution of depth-related depositional features has led to regional recognition of smaller-scale shallowing-upward cyclicity contained within each large-scale sequence. Such smaller-scale cyclicity encompasses stratigraphic intervals of 1--10 m thickness, with estimated durations of 0.5--1.5 Ma. The St. Peter Sandst. has long been regarded asmore » a classic transgressive sheet sand. However, four discrete shallowing-upward packages characterize the St. Peter-Glenwood interval regionally (IA, MN, NB, KS), including western facies displaying coarsening-upward sandstone packages with condensed conodont-rich brown shale and phosphatic sediments in their lower part (local oolitic ironstone), commonly above pyritic hardgrounds. Regional continuity of small-scale cyclic patterns in M. Ord. strata of the Iowa area may suggest eustatic controls; this can be tested through inter-regional comparisons.« less

Fat fractal scaling of drainage networks from a random spatial network model

USGS Publications Warehouse

Karlinger, Michael R.; Troutman, Brent M.

1992-01-01

An alternative quantification of the scaling properties of river channel networks is explored using a spatial network model. Whereas scaling descriptions of drainage networks previously have been presented using a fractal analysis primarily of the channel lengths, we illustrate the scaling of the surface area of the channels defining the network pattern with an exponent which is independent of the fractal dimension but not of the fractal nature of the network. The methodology presented is a fat fractal analysis in which the drainage basin minus the channel area is considered the fat fractal. Random channel networks within a fixed basin area are generated on grids of different scales. The sample channel networks generated by the model have a common outlet of fixed width and a rule of upstream channel narrowing specified by a diameter branching exponent using hydraulic and geomorphologic principles. Scaling exponents are computed for each sample network on a given grid size and are regressed against network magnitude. Results indicate that the size of the exponents are related to magnitude of the networks and generally decrease as network magnitude increases. Cases showing differences in scaling exponents with like magnitudes suggest a direction of future work regarding other topologic basin characteristics as potential explanatory variables.

Stormwater pollution in suburban ecosystems: the role of residential rooftop connectivity

NASA Astrophysics Data System (ADS)

Miles, B.; Band, L. E.

2013-12-01

Stormwater pollution has been recognized as a major concern of urban sustainability. Understanding interactions between urban landcover and stormwater pollution can be advanced through the development of spatially explicit ecohydrology models that simulate fine-scale residential stormwater management; this requires high-resolution LIDAR and landcover data, as well as field observation at the household scale. The objective of my research is to improve understanding of how parcel-scale heterogeneity of impervious and previous surfaces effect stormwater volume. In support of this objective, I present results from work to: (1) perform field observation of existing patterns of residential rooftop connectivity to nearby impervious surfaces; (2) modify the Regional Hydro-Ecological Simulation System (RHESSys) to explicitly represent non-topographic surface flow routing of rooftops; and (3) develop RHESSys models for urban-suburban headwater watersheds in Baltimore, MD (as part of the Baltimore Ecosystem Study (BES) NSF Long-Term Ecological Research (LTER) site) and Durham, NC (as part of the NSF Urban Long-Term Research Area (ULTRA) program). I use these models to simulate stormwater volume resulting from both baseline residential rooftop impervious connectivity and for disconnection scenarios (e.g. roof drainage to lawn v. engineered rain garden, upslope v. riparian). This research will help to improve representation of fine-scale surface flow features in urban ecohydrology modeling while informing policy decisions over how best to implement parcel-scale retrofits in existing neighborhoods to reduce stormwater pollution at the watershed scale.

Dose assessment of 2% chlorhexidine acetate for canine superficial pyoderma.

PubMed

Murayama, Nobuo; Terada, Yuri; Okuaki, Mio; Nagata, Masahiko

2011-10-01

The dose of 2% chlorhexidine acetate (2CA; Nolvasan(®) Surgical Scrub; Fort Dodge Animal Health, Fort Dodge, IA, USA) for canine superficial pyoderma was evaluated. The first trial compared three doses (group 1, 57 mL/m(2) body surface area; group 2, 29 mL/m(2) body surface area; and group 3, 19 mL/m(2) body surface area) in a randomized, double-blind, controlled fashion. Twenty-seven dogs with superficial pyoderma were treated with 2CA at the allocated doses every 2 days for 1 week. The owners and investigators subjectively evaluated the dogs, and investigators scored skin lesions, including erythema, papules/pustules, alopecia and scales, on a 0-4 scale. There were no significant differences in response between the treatment groups. The second trial established a practical dose-measuring method for 2CA. Sixty-eight owners were asked to apply 2CA on their palm in an amount corresponding to a Japanese ¥500 coin, 26.5 mm in diameter. This yielded an average dose of 0.90±0.40 mL. Mathematically, the doses used in groups 1, 2 and 3 can be represented as one coin per approximately one-, two- and three-hand-sized lesions, respectively. The results therefore suggest that owners instructed to apply one coin of the product per two-hand-sized areas of superficial pyoderma would use the range of doses evaluated in this trial. © 2011 The Authors. Veterinary Dermatology. © 2011 ESVD and ACVD.

The Spatial Resolution in the Computer Modelling of Atmospheric Flow over a Double-Hill Forested Region

NASA Astrophysics Data System (ADS)

Palma, J. L.; Rodrigues, C. V.; Lopes, A. S.; Carneiro, A. M. C.; Coelho, R. P. C.; Gomes, V. C.

2017-12-01

With the ever increasing accuracy required from numerical weather forecasts, there is pressure to increase the resolution and fidelity employed in computational micro-scale flow models. However, numerical studies of complex terrain flows are fundamentally bound by the digital representation of the terrain and land cover. This work assess the impact of the surface description on micro-scale simulation results at a highly complex site in Perdigão, Portugal, characterized by a twin parallel ridge topography, densely forested areas and an operating wind turbine. Although Coriolis and stratification effects cannot be ignored, the study is done under neutrally stratified atmosphere and static inflow conditions. The understanding gained here will later carry over to WRF-coupled simulations, where those conditions do not apply and the flow physics is more accurately modelled. With access to very fine digital mappings (<1m horizontal resolution) of both topography and land cover (roughness and canopy cover, both obtained through aerial LIDAR scanning of the surface) the impact of each element of the surface description on simulation results can be individualized, in order to estimate the resolution required to satisfactorily resolve them. Starting from the bare topographic description, in its coursest form, these include: a) the surface roughness mapping, b) the operating wind turbine, c) the canopy cover, as either body forces or added surface roughness (akin to meso-scale modelling), d) high resolution topography and surface cover mapping. Each of these individually will have an impact near the surface, including the rotor swept area of modern wind turbines. Combined they will considerably change flow up to boundary layer heights. Sensitivity to these elements cannot be generalized and should be assessed case-by-case. This type of in-depth study, unfeasible using WRF-coupled simulations, should provide considerable insight when spatially allocating mesh resolution for accurate resolution of complex flows.

Overland flow connectivity on planar patchy hillslopes - modified percolation theory approaches and combinatorial model of urns

NASA Astrophysics Data System (ADS)

Nezlobin, David; Pariente, Sarah; Lavee, Hanoch; Sachs, Eyal

2017-04-01

Source-sink systems are very common in hydrology; in particular, some land cover types often generate runoff (e.g. embedded rocks, bare soil) , while other obstruct it (e.g. vegetation, cracked soil). Surface runoff coefficients of patchy slopes/plots covered by runoff generating and obstructing covers (e.g., bare soil and vegetation) depend critically on the percentage cover (i.e. sources/sinks abundance) and decrease strongly with observation scale. The classic mathematical percolation theory provides a powerful apparatus for describing the runoff connectivity on patchy hillslopes, but it ignores strong effect of the overland flow directionality. To overcome this and other difficulties, modified percolation theory approaches can be considered, such as straight percolation (for the planar slopes), quasi-straight percolation and models with limited obstruction. These approaches may explain both the observed critical dependence of runoff coefficients on percentage cover and their scale decrease in systems with strong flow directionality (e.g. planar slopes). The contributing area increases sharply when the runoff generating percentage cover approaches the straight percolation threshold. This explains the strong increase of the surface runoff and erosion for relatively low values (normally less than 35%) of the obstructing cover (e.g., vegetation). Combinatorial models of urns with restricted occupancy can be applied for the analytic evaluation of meaningful straight percolation quantities, such as NOGA's (Non-Obstructed Generating Area) expected value and straight percolation probability. It is shown that the nature of the cover-related runoff scale decrease is combinatorial - the probability for the generated runoff to avoid obstruction in unit area decreases with scale for the non-trivial percentage cover values. The magnitude of the scale effect is found to be a skewed non-monotonous function of the percentage cover. It is shown that the cover-related scale effect becomes less prominent if the obstructing capacity decreases, as generally occurs during heavy rainfalls. The plot width have a moderate positive statistical effect on runoff and erosion coefficients, since wider patchy plots have, on average, a greater normalized contributing area and a higher probability to have runoff of a certain length. The effect of plot width depends by itself on the percentage cover, plot length, and compared width scales. The contributing area uncertainty brought about by cover spatial arrangement is examined, including its dependence on the percentage cover and scale. In general, modified percolation theory approaches and combinatorial models of urns with restricted occupancy may link between critical dependence of runoff on percentage cover, cover-related scale effect, and statistical uncertainty of the observed quantities.

A Multiscale Surface Water Temperature Data Acquisition Platform: Tests on Lake Geneva, Switzerland

NASA Astrophysics Data System (ADS)

Barry, D. A.; Irani Rahaghi, A.; Lemmin, U.; Riffler, M.; Wunderle, S.

2015-12-01

An improved understanding of surface transport processes is necessary to predict sediment, pollutant and phytoplankton patterns in large lakes. Lake surface water temperature (LSWT), which varies in space and time, reflects meteorological and climatological forcing more than any other physical lake parameter. There are different data sources for LSWT mapping, including remote sensing and in situ measurements. Satellite data can be suitable for detecting large-scale thermal patterns, but not meso- or small scale processes. Lake surface thermography, investigated in this study, has finer resolution compared to satellite images. Thermography at the meso-scale provides the ability to ground-truth satellite imagery over scales of one to several satellite image pixels. On the other hand, thermography data can be used as a control in schemes to upscale local measurements that account for surface energy fluxes and the vertical energy budget. Independently, since such data can be collected at high frequency, they can be also useful in capturing changes in the surface signatures of meso-scale eddies and thus to quantify mixing processes. In the present study, we report results from a Balloon Launched Imaging and Monitoring Platform (BLIMP), which was developed in order to measure the LSWT at meso-scale. The BLIMP consists of a small balloon that is tethered to a boat and equipped with thermal and RGB cameras, as well as other instrumentation for location and communication. Several deployments were carried out on Lake Geneva. In a typical deployment, the BLIMP is towed by a boat, and collects high frequency data from different heights (i.e., spatial resolutions) and locations. Simultaneous ground-truthing of the BLIMP data is achieved using an autonomous craft that collects a variety of data, including in situ surface/near surface temperatures, radiation and meteorological data in the area covered by the BLIMP images. With suitable scaling, our results show good consistency between in situ, BLIMP and concurrent satellite data. In addition, the BLIMP thermography reveals (hydrodynamically-driven) structures in the LSWT - an obvious example being mixing of river discharges.

The fourth dimension of life: fractal geometry and allometric scaling of organisms.

PubMed

West, G B; Brown, J H; Enquist, B J

1999-06-04

Fractal-like networks effectively endow life with an additional fourth spatial dimension. This is the origin of quarter-power scaling that is so pervasive in biology. Organisms have evolved hierarchical branching networks that terminate in size-invariant units, such as capillaries, leaves, mitochondria, and oxidase molecules. Natural selection has tended to maximize both metabolic capacity, by maximizing the scaling of exchange surface areas, and internal efficiency, by minimizing the scaling of transport distances and times. These design principles are independent of detailed dynamics and explicit models and should apply to virtually all organisms.

GeoComplexity and scale: surface processes and remote sensing of geosystems. GeoComplexity and scale: surface processes and remote sensing of geosystems

NASA Astrophysics Data System (ADS)

Muller, Jan-Peter

2015-04-01

Understanding the role of scaling in different planetary surface processes within our Solar System is one of the fundamental goals of planetary and solid earth scientific research. There has been a revolution in planetary surface observations over the past decade for the Earth, Mars and the Moon, especially in 3D imaging of surface shape (from the planetary scale down to resolutions of 75cm). I will examine three areas that I have been active in over the last 25 years giving examples of newly processed global datasets ripe for scaling analysis: topography, BRDF/albedo and imaging. For understanding scaling in terrestrial land surface topography we now have global 30m digital elevation models (DEMs) from different types of sensors (InSAR and stereo-optical) along with laser altimeter data to provide global reference models (to better than 1m in cross-over areas) and airborne laser altimeter data over small areas at resolutions better than 1m and height accuracies better than 10-15cm. We also have an increasing number of sub-surface observations from long wavelength SAR in arid regions, which will allow us to look at the true surface rather than the one buried by sand. We also still have a major limitation of these DEMs in that they represent an unknown observable surface with C-band InSAR DEMs representing being somewhere near the top of the canopy and X-band InSAR and stereo near the top of the canopy but only P-band representing the true understorey surface. I will present some of the recent highlights of topography on Mars including 3D modelling of surface shape from the ESA Mars Express HRSC (High Resolution Stereo Camera), see [1], [2] at 30-100m grid-spacing; and then co-registered to HRSC using a resolution cascade of 20m DTMs from NASA MRO stereo-CTX and 0.75m digital terrain models (as there is no land cover on Mars) DTMs from MRO stereo-HiRISE [3]. Comparable DTMs now exist for the Moon from 100m up to 1m. I will show examples of these DEM/DTM datasets along with some simple analyses of their scaling properties. Global 1km, 8-daily terrestrial land surface BRDF/albedo maps exist for US sensors from MODIS and by orbit from MISR. More recently, the ESA GlobAlbedo project [4] has produced land surface datasets on the same spatio-temporal sampling using optimal estimation with full uncertainty matrices associated with each and every 1km pixel. By exploiting these uncertainty estimates I show how upscaling can be performed as well as analysing their scaling properties. Recently, a very novel technique for the super-resolution restoration (SRR) of stacks of images has been developed at UCL [5]. First examples shown will be of the entire MER-A Spirit rover traverse taking a stack of 25cm HiRISE to generate a corridor of SRR images along the rover traverse of 5cm imagery of unresolved features such as rocks, created as a consequence of meteoritic bombardment, ridge and valley features. This SRR technique will allow us for ≈400 areas on Mars (where 5 or more HiRISE images have been captured) and similar numbers on the Moon to resolve sub-pixel features. Examples will be shown of how these SRR images can be employed to assist with the better understanding of surface geomorphology. Acknowledgements: The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under PRoViDE grant agreement n˚312377 and the ESA GlobAlbedo project. Partial support is also provided from the STFC "MSSL Consolidated Grant" ST/K000977/1. References: [1] Gwinner, K., F. et al. (2010) Topography of Mars from global mapping by HRSC high-resolution digital terrain models and orthoimages: characteristics and performance. Earth and Planetary Science Letters 294, 506-519, doi:10.1016/j.epsl.2009.11.007, 2010; [2] Gwinner, K., Muller, J-P., et al. (2015) MarsExpress High Resolution Stereo Camera (HRSC) Multi-orbit Data Products: Methodology, Mapping Concepts and Performance for the first Quadrangle (MC-11E). Geophysical Research Abstracts, Vol. 17, EGU2015-13832; [3] Kim, J., & Muller, J. (2009). Multi-resolution topographic data extraction from Martian stereo imagery. Planetary and Space Science, 57, 2095-2112. doi:10.1016/j.pss.2009.09.024; [4] Muller, J.-P., et al. (2011), The ESA GlobAlbedo Project for mapping the Earth's land surface albedo for 15 Years from European Sensors., Geophysical Research Abstracts, Vol. 13, EGU2011-10969; [5] Tao, Y., Muller, J.-P. (2015) Supporting lander and rover operation: a novel super-resolution restoration technique. Geophysical Research Abstracts, Vol. 17, EGU2015-6925

Terrain profiling from Seasat altimetry

NASA Technical Reports Server (NTRS)

Brooks, R. L.

1981-01-01

To determine their applicability for terrain profiling, Seasat altimeter measurements were analyzed for the following geographic areas: (1) Andean salars of southern Bolivia; (2) Alaska; (3) south-central Arizona; (4) imperial Valley of California; (5) Yuma Valley of Arizona; and (6) Great Salt Lake Desert. Analysis of the data over all of these geographic areas shows that the satellite altimeter servo did not respond quickly enough to changing terrain features. However, it is demonstrated that retracking of the archived surface return waveforms yields surface elevations over smooth terrain accurate to + or - 1 m when correlated with large scale maps. The retracking algorithm used and its verification over the salars of southern Bolivia are described. Results are presented for each of the six geographic areas.

On the impact of snow cover on daytime pollution dispersion

NASA Astrophysics Data System (ADS)

Segal, M.; Garratt, J. R.; Pielke, R. A.; Hildebrand, P.; Rogers, F. A.; Cramer, J.; Schanot, A.

A preliminary evaluation of the impact of snow cover on daytime pollutant dispersion conditions is made by using conceptual, scaling, and observational analyses. For uniform snow cover and synoptically unperturbed sunny conditions, observations indicate a considerate suppression of the surface sensible heat flux, the turbulence, and the development of the daytime atmospheric boundary layer (ABL) when compared to snow-free conditions. However, under conditions of non-uniform snow cover, as in urban areas, or associated with vegetated areas or bare ground patches, a milder effect on pollutant dispersion conditions would be expected. Observed concentrations of atmospheric particles within the ABL, and surface pollutant concentrations in urban areas, reflect the impact of snow cover on the modification of ABL characteristics.

Climatological Factors Affecting Electromagnetic Surface Ducting in the Aegean Sea Region

DTIC Science & Technology

2012-03-01

low precipitation, and northeasterly winds, all due to changes in large scale circulations and a northward shift in extratropical storm tracks. The...differences over the Aegean region, that are governed by large-scale climate factors. a. Winter During winter, the Aegean area is subject to extratropical ... extratropical cyclones from entering the Aegean region, while opposite shifts can 18 allow extratropical cyclones to more frequently enter the Aegean

Development of Micro-Scale Assays of Mammary Stem and Progenitor Cells

DTIC Science & Technology

2008-07-01

visualization via phase contrast along the length of the channel. Additionally, most devices can be placed on any substrate, allowing glass to be...microenvironment composition due to increases in surface area to volume ratios as the scale of the culture is reduced. Purcell provided a very useful account...cultures are performed in polysytrene (or glass bottomed) tissue culture flasks, dishes and plates. While many microfluidic cultures are performed

Quantitative Estimation of Land Surface Characteristic Parameters and Actual Evapotranspiration in the Nagqu River Basin over the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Zhong, L.; Ma, Y.; Ma, W.; Zou, M.; Hu, Y.

2016-12-01

Actual evapotranspiration (ETa) is an important component of the water cycle in the Tibetan Plateau. It is controlled by many hydrological and meteorological factors. Therefore, it is of great significance to estimate ETa accurately and continuously. It is also drawing much attention of scientific community to understand land surface parameters and land-atmosphere water exchange processes in small watershed-scale areas. Based on in-situ meteorological data in the Nagqu river basin and surrounding regions, the main meteorological factors affecting the evaporation process were quantitatively analyzed and the point-scale ETa estimation models in the study area were successfully built. On the other hand, multi-source satellite data (such as SPOT, MODIS, FY-2C) were used to derive the surface characteristics in the river basin. A time series processing technique was applied to remove cloud cover and reconstruct data series. Then improved land surface albedo, improved downward shortwave radiation flux and reconstructed normalized difference vegetation index (NDVI) were coupled into the topographical enhanced surface energy balance system to estimate ETa. The model-estimated results were compared with those ETa values determined by combinatory method. The results indicated that the model-estimated ETa agreed well with in-situ measurements with correlation coefficient, mean bias error and root mean square error of 0.836, 0.087 and 0.140 mm/h respectively.

Estimating restorable wetland water storage at landscape scales

EPA Science Inventory

Globally, hydrologic modifications such as ditching and subsurface drainage have significantly reduced wetland water storage capacity (i.e., the volume of surface water a wetland can retain) and consequent wetland functions. While wetland area has been well documented across many...

Analysis of the ability of large-scale reanalysis data to define Siberian fire danger in preparation for future fire prediction

NASA Astrophysics Data System (ADS)

Soja, Amber; Westberg, David; Stackhouse, Paul, Jr.; McRae, Douglas; Jin, Ji-Zhong; Sukhinin, Anatoly

2010-05-01

Fire is the dominant disturbance that precipitates ecosystem change in boreal regions, and fire is largely under the control of weather and climate. Fire frequency, fire severity, area burned and fire season length are predicted to increase in boreal regions under current climate change scenarios. Therefore, changes in fire regimes have the potential to compel ecological change, moving ecosystems more quickly towards equilibrium with a new climate. The ultimate goal of this research is to assess the viability of large-scale (1°) data to be used to define fire weather danger and fire regimes, so that large-scale data can be confidently used to predict future fire regimes using large-scale fire weather data, like that available from current Intergovernmental Panel on Climate Change (IPCC) climate change scenarios. In this talk, we intent to: (1) evaluate Fire Weather Indices (FWI) derived using reanalysis and interpolated station data; (2) discuss the advantages and disadvantages of using these distinct data sources; and (3) highlight established relationships between large-scale fire weather data, area burned, active fires and ecosystems burned. Specifically, the Canadian Forestry Service (CFS) Fire Weather Index (FWI) will be derived using: (1) NASA Goddard Earth Observing System version 4 (GEOS-4) large-scale reanalysis and NASA Global Precipitation Climatology Project (GPCP) data; and National Climatic Data Center (NCDC) surface station-interpolated data. Requirements of the FWI are local noon surface-level air temperature, relative humidity, wind speed, and daily (noon-noon) rainfall. GEOS-4 reanalysis and NCDC station-interpolated fire weather indices are generally consistent spatially, temporally and quantitatively. Additionally, increased fire activity coincides with increased FWI ratings in both data products. Relationships have been established between large-scale FWI to area burned, fire frequency, ecosystem types, and these can be use to estimate historic and future fire regimes.

Application of surface analytical methods for hazardous situation in the Adriatic Sea: monitoring of organic matter dynamics and oil pollution

NASA Astrophysics Data System (ADS)

Pletikapić, Galja; Ivošević DeNardis, Nadica

2017-01-01

Surface analytical methods are applied to examine the environmental status of seawaters. The present overview emphasizes advantages of combining surface analytical methods, applied to a hazardous situation in the Adriatic Sea, such as monitoring of the first aggregation phases of dissolved organic matter in order to potentially predict the massive mucilage formation and testing of oil spill cleanup. Such an approach, based on fast and direct characterization of organic matter and its high-resolution visualization, sets a continuous-scale description of organic matter from micro- to nanometre scales. Electrochemical method of chronoamperometry at the dropping mercury electrode meets the requirements for monitoring purposes due to the simple and fast analysis of a large number of natural seawater samples enabling simultaneous differentiation of organic constituents. In contrast, atomic force microscopy allows direct visualization of biotic and abiotic particles and provides an insight into structural organization of marine organic matter at micro- and nanometre scales. In the future, merging data at different spatial scales, taking into account experimental input on micrometre scale, observations on metre scale and modelling on kilometre scale, will be important for developing sophisticated technological platforms for knowledge transfer, reports and maps applicable for the marine environmental protection and management of the coastal area, especially for tourism, fishery and cruiser trafficking.

GIS based optimal impervious surface map generation using various spatial data for urban nonpoint source management.

PubMed

Lee, Cholyoung; Kim, Kyehyun; Lee, Hyuk

2018-01-15

Impervious surfaces are mainly artificial structures such as rooftops, roads, and parking lots that are covered by impenetrable materials. These surfaces are becoming the major causes of nonpoint source (NPS) pollution in urban areas. The rapid progress of urban development is increasing the total amount of impervious surfaces and NPS pollution. Therefore, many cities worldwide have adopted a stormwater utility fee (SUF) that generates funds needed to manage NPS pollution. The amount of SUF is estimated based on the impervious ratio, which is calculated by dividing the total impervious surface area by the net area of an individual land parcel. Hence, in order to identify the exact impervious ratio, large-scale impervious surface maps (ISMs) are necessary. This study proposes and assesses various methods for generating large-scale ISMs for urban areas by using existing GIS data. Bupyeong-gu, a district in the city of Incheon, South Korea, was selected as the study area. Spatial data that were freely offered by national/local governments in S. Korea were collected. First, three types of ISMs were generated by using the land-cover map, digital topographic map, and orthophotographs, to validate three methods that had been proposed conceptually by Korea Environment Corporation. Then, to generate an ISM of higher accuracy, an integration method using all data was proposed. Error matrices were made and Kappa statistics were calculated to evaluate the accuracy. Overlay analyses were performed to examine the distribution of misclassified areas. From the results, the integration method delivered the highest accuracy (Kappa statistic of 0.99) compared to the three methods that use a single type of spatial data. However, a longer production time and higher cost were limiting factors. Among the three methods using a single type of data, the land-cover map showed the highest accuracy with a Kappa statistic of 0.91. Thus, it was judged that the mapping method using the land-cover map is more appropriate than the others. In conclusion, it is desirable to apply the integration method when generating the ISM with the highest accuracy. However, if time and cost are constrained, it would be effective to primarily use the land-cover map. Copyright © 2017 Elsevier Ltd. All rights reserved.

Poroelastic Response to the 2012 Costa Rica Earthquake and the Effects on Geodetic Surface Deformation and Groundwater Fluxes

NASA Astrophysics Data System (ADS)

McCormack, K. A.; Hesse, M.

2016-12-01

Remote sensing and geodetic measurements are providing a new wealth of spatially distributed, time-series data that have the ability to improve our understanding of co-seismic rupture and post-seismic processes in subduction zones. Following a large earthquake, large-scale deformation is influenced by a myriad of post-seismic processes occurring on different spatial and temporal scales. These include continued slip on the fault plane (after-slip), a poroelastic response due to the movement of over-pressurized groundwater and viscoelastic relaxation of the underlying mantle. Often, the only means of observing these phenomena are through surface deformation measurements - either GPS or InSAR. Such tools measure the combined result of all these processes, which makes studying the effects of any single process difficult. For the 2012 Mw 7.6 Costa Rica Earthquake, we formulate a Bayesian inverse problem to infer the slip distribution on the plate interface using an elastic finite element model and GPS surface deformation measurements. From this study we identify a horseshoe-shaped rupture area surrounding a locked patch that is likely to release stress in the future. The results of our inversion are then used as an initial condition in a coupled poroelastic forward model to investigate the role of poroelastic effects on post-seismic deformation and stress transfer. We model the co-seismic pore pressure change as well as the pressure evolution and resulting deformation in the months after the earthquake. The surface permeability field is constrained by pump-test data from 526 groundwater wells throughout the study area. The results of the forward model indicate that earthquake-induced pore pressure changes dissipate quickly in most areas near the surface, resulting in relaxation of the surface in the seven to twenty days following the earthquake. Near the subducting slab interface, pore pressure changes can be an order of magnitude larger and may persist for many months after the earthquake. Dissipation of earthquake-induced pore pressure in deeper, low permeability areas manifests as surface deformation over a much longer timescale - on the order of months - which may influence the interpretation of longer timescale post-seismic deformation as purely viscoelastic relaxation.

On Feature Extraction from Large Scale Linear LiDAR Data

NASA Astrophysics Data System (ADS)

Acharjee, Partha Pratim

Airborne light detection and ranging (LiDAR) can generate co-registered elevation and intensity map over large terrain. The co-registered 3D map and intensity information can be used efficiently for different feature extraction application. In this dissertation, we developed two algorithms for feature extraction, and usages of features for practical applications. One of the developed algorithms can map still and flowing waterbody features, and another one can extract building feature and estimate solar potential on rooftops and facades. Remote sensing capabilities, distinguishing characteristics of laser returns from water surface and specific data collection procedures provide LiDAR data an edge in this application domain. Furthermore, water surface mapping solutions must work on extremely large datasets, from a thousand square miles, to hundreds of thousands of square miles. National and state-wide map generation/upgradation and hydro-flattening of LiDAR data for many other applications are two leading needs of water surface mapping. These call for as much automation as possible. Researchers have developed many semi-automated algorithms using multiple semi-automated tools and human interventions. This reported work describes a consolidated algorithm and toolbox developed for large scale, automated water surface mapping. Geometric features such as flatness of water surface, higher elevation change in water-land interface and, optical properties such as dropouts caused by specular reflection, bimodal intensity distributions were some of the linear LiDAR features exploited for water surface mapping. Large-scale data handling capabilities are incorporated by automated and intelligent windowing, by resolving boundary issues and integrating all results to a single output. This whole algorithm is developed as an ArcGIS toolbox using Python libraries. Testing and validation are performed on a large datasets to determine the effectiveness of the toolbox and results are presented. Significant power demand is located in urban areas, where, theoretically, a large amount of building surface area is also available for solar panel installation. Therefore, property owners and power generation companies can benefit from a citywide solar potential map, which can provide available estimated annual solar energy at a given location. An efficient solar potential measurement is a prerequisite for an effective solar energy system in an urban area. In addition, the solar potential calculation from rooftops and building facades could open up a wide variety of options for solar panel installations. However, complex urban scenes make it hard to estimate the solar potential, partly because of shadows cast by the buildings. LiDAR-based 3D city models could possibly be the right technology for solar potential mapping. Although, most of the current LiDAR-based local solar potential assessment algorithms mainly address rooftop potential calculation, whereas building facades can contribute a significant amount of viable surface area for solar panel installation. In this paper, we introduce a new algorithm to calculate solar potential of both rooftop and building facades. Solar potential received by the rooftops and facades over the year are also investigated in the test area.

Biomimetic patterned surfaces for controllable friction in micro- and nanoscale devices

NASA Astrophysics Data System (ADS)

Singh, Arvind; Suh, Kahp-Yang

2013-12-01

Biomimetics is the study and simulation of biological systems for desired functional properties. It involves the transformation of underlying principles discovered in nature into man-made technologies. In this context, natural surfaces have significantly inspired and motivated new solutions for micro- and nano-scale devices (e.g., Micro/Nano-Electro-Mechanical Systems, MEMS/NEMS) towards controllable friction, during their operation. As a generic solution to reduce friction at small scale, various thin films/coatings have been employed in the last few decades. In recent years, inspiration from `Lotus Effect' has initiated a new research direction for controllable friction with biomimetic patterned surfaces. By exploiting the intrinsic hydrophobicity and ability to reduce contact area, such micro- or nano-patterned surfaces have demonstrated great strength and potential for applications in MEMS/NEMS devices. This review highlights recent advancements on the design, development and performance of these biomimetic patterned surfaces. Also, we present some hybrid approaches to tackle current challenges in biomimetic tribological applications for MEMS/NEMS devices.

Generation of High Resolution Land Surface Parameters in the Community Land Model

NASA Astrophysics Data System (ADS)

Ke, Y.; Coleman, A. M.; Wigmosta, M. S.; Leung, L.; Huang, M.; Li, H.

2010-12-01

The Community Land Model (CLM) is the land surface model used for the Community Atmosphere Model (CAM) and the Community Climate System Model (CCSM). It examines the physical, chemical, and biological processes across a variety of spatial and temporal scales. Currently, efforts are being made to improve the spatial resolution of the CLM, in part, to represent finer scale hydrologic characteristics. Current land surface parameters of CLM4.0, in particular plant functional types (PFT) and leaf area index (LAI), are generated from MODIS and calculated at a 0.05 degree resolution. These MODIS-derived land surface parameters have also been aggregated to coarser resolutions (e.g., 0.5, 1.0 degrees). To evaluate the response of CLM across various spatial scales, higher spatial resolution land surface parameters need to be generated. In this study we examine the use of Landsat TM/ETM+ imagery and data fusion techniques for generating land surface parameters at a 1km resolution within the Pacific Northwest United States. . Land cover types and PFTs are classified based on Landsat multi-season spectral information, DEM, National Land Cover Database (NLCD) and the USDA-NASS Crop Data Layer (CDL). For each PFT, relationships between MOD15A2 high quality LAI values, Landsat-based vegetation indices, climate variables, terrain, and laser-altimeter derived vegetation height are used to generate monthly LAI values at a 30m resolution. The high-resolution PFT and LAI data are aggregated to create a 1km model grid resolution. An evaluation and comparison of CLM land surface response at both fine and moderate scale is presented.

Structure, biomimetics, and fluid dynamics of fish skin surfaces*

NASA Astrophysics Data System (ADS)

Lauder, George V.; Wainwright, Dylan K.; Domel, August G.; Weaver, James C.; Wen, Li; Bertoldi, Katia

2016-10-01

The interface between the fluid environment and the surface of the body in swimming fishes is critical for both physiological and hydrodynamic functions. The skin surface in most species of fishes is covered with bony scales or toothlike denticles (in sharks). Despite the apparent importance of fish surfaces for understanding aquatic locomotion and near-surface boundary layer flows, relatively little attention has been paid to either the nature of surface textures in fishes or possible hydrodynamic effects of variation in roughness around the body surface within an individual and among species. Fish surfaces are remarkably diverse and in many bony fishes scales can have an intricate surface texture with projections, ridges, and comblike extensions. Shark denticles (or scales) are toothlike and project out of the skin to form a complexly textured surface that interacts with free-stream flow. Manufacturing biomimetic foils with fishlike surfaces allows hydrodynamic testing and we emphasize here the importance of dynamic test conditions where the effect of surface textures is assessed under conditions of self-propulsion. We show that simple two-dimensional foils with patterned cuts do not perform as well as a smooth control surface, but that biomimetic shark skin foils can swim at higher self-propelled speeds than smooth controls. When the arrangement of denticles on the foil surface is altered, we find that a staggered-overlapped pattern outperforms other arrangements. Flexible foils made of real shark skin outperform sanded controls when foils are moved with a biologically realistic motion program. We suggest that focus on the mechanisms of drag reduction by fish surfaces has been too limiting and an additional role of fish surface textures may be to alter leading edge vortices and flow patterns on moving surfaces in a way that enhances thrust. Analysis of water flow over an artificial shark skin foil under both static and dynamic conditions shows that a shear layer develops over the denticle surface and we propose that there is limited flow under the expanded surfaces of shark denticles. The diversity of fish scale types and textures and the effect of these surfaces on boundary layer flows and fish locomotor energetics is a rich area for future investigation.

Probing the intrinsically oil-wet surfaces of pores in North Sea chalk at subpore resolution.

PubMed

Hassenkam, T; Skovbjerg, L L; Stipp, S L S

2009-04-14

Pore surface properties control oil recovery. This is especially true for chalk reservoirs, where pores are particularly small. Wettability, the tendency for a surface to cover itself with fluid, is traditionally defined by the angle a droplet makes with a surface, but this macroscopic definition is meaningless when the particles are smaller than even the smallest droplet. Understanding surface wetting, at the pore scale, will provide clues for more effective oil recovery. We used a special mode of atomic force microscopy and a hydrophobic tip to collect matrices of 10,000 force curves over 5- x 5-mum(2) areas on internal pore surfaces and constructed maps of topography, adhesion, and elasticity. We investigated chalk samples from a water-bearing formation in the Danish North Sea oil fields that had never seen oil. Wettability and elasticity were inhomogeneous over scales of 10s of nanometers, smaller than individual chalk particles. Some areas were soft and hydrophobic, whereas others showed no correlation between hardness and adhesion. We conclude that the macroscopic parameter, "wetting," averages the nanoscopic behavior along fluid pathways, and "mixed-wet" samples have patches with vastly different properties. Development of reservoir hydrophobicity has been attributed to infiltrating oil, but these new results prove that wettability and elasticity are inherent properties of chalk. Their variability, even on single particles, must result from material originally present during sedimentation or material sorbed from the pore fluid some time later.

Probing the intrinsically oil-wet surfaces of pores in North Sea chalk at subpore resolution

PubMed Central

Hassenkam, T.; Skovbjerg, L. L.; Stipp, S. L. S.

2009-01-01

Pore surface properties control oil recovery. This is especially true for chalk reservoirs, where pores are particularly small. Wettability, the tendency for a surface to cover itself with fluid, is traditionally defined by the angle a droplet makes with a surface, but this macroscopic definition is meaningless when the particles are smaller than even the smallest droplet. Understanding surface wetting, at the pore scale, will provide clues for more effective oil recovery. We used a special mode of atomic force microscopy and a hydrophobic tip to collect matrices of 10,000 force curves over 5- × 5-μm2 areas on internal pore surfaces and constructed maps of topography, adhesion, and elasticity. We investigated chalk samples from a water-bearing formation in the Danish North Sea oil fields that had never seen oil. Wettability and elasticity were inhomogeneous over scales of 10s of nanometers, smaller than individual chalk particles. Some areas were soft and hydrophobic, whereas others showed no correlation between hardness and adhesion. We conclude that the macroscopic parameter, “wetting,” averages the nanoscopic behavior along fluid pathways, and “mixed-wet” samples have patches with vastly different properties. Development of reservoir hydrophobicity has been attributed to infiltrating oil, but these new results prove that wettability and elasticity are inherent properties of chalk. Their variability, even on single particles, must result from material originally present during sedimentation or material sorbed from the pore fluid some time later. PMID:19321418

Report for Full-Scale Mulch Wall Treatment of Chlorinated Hydrocarbon-Impacted Groundwater

DTIC Science & Technology

2004-04-13

7.1 Direction of Groundwater Flow Through the Test Area Static water level measurements were taken every quarter after the installation of the...volatile organic compounds, alternate electron acceptors/byproducts and water quality parameters. Potentiometric surface maps showed the groundwater ... groundwater and surface water restrictions 10 Established clear zone (3000 ft by 3000 ft) Building 301 CEA Previously installed soil boring MW-19I 19

Porous Structures in Stacked, Crumpled and Pillared Graphene-Based 3D Materials.

PubMed

Guo, Fei; Creighton, Megan; Chen, Yantao; Hurt, Robert; Külaots, Indrek

2014-01-01

Graphene, an atomically thin material with the theoretical surface area of 2600 m 2 g -1 , has great potential in the fields of catalysis, separation, and gas storage if properly assembled into functional 3D materials at large scale. In ideal non-interacting ensembles of non-porous multilayer graphene plates, the surface area can be adequately estimated using the simple geometric law ~ 2600 m 2 g -1 /N, where N is the number of graphene sheets per plate. Some processing operations, however, lead to secondary plate-plate stacking, folding, crumpling or pillaring, which give rise to more complex structures. Here we show that bulk samples of multilayer graphene plates stack in an irregular fashion that preserves the 2600/N surface area and creates regular slot-like pores with sizes that are multiples of the unit plate thickness. In contrast, graphene oxide deposits into films with massive area loss (2600 to 40 m 2 g -1 ) due to nearly perfect alignment and stacking during the drying process. Pillaring graphene oxide sheets by co-deposition of colloidal-phase particle-based spacers has the potential to partially restore the large monolayer surface. Surface areas as high as 1000 m 2 g -1 are demonstrated here through colloidal-phase deposition of graphene oxide with water-dispersible aryl-sulfonated ultrafine carbon black as a pillaring agent.

VIRTIS on Venus Express: retrieval of real surface emissivity on global scales

NASA Astrophysics Data System (ADS)

Arnold, Gabriele E.; Kappel, David; Haus, Rainer; Telléz Pedroza, Laura; Piccioni, Giuseppe; Drossart, Pierre

2015-09-01

The extraction of surface emissivity data provides the data base for surface composition analyses and enables to evaluate Venus' geology. The Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS) aboard ESA's Venus Express mission measured, inter alia, the nightside thermal emission of Venus in the near infrared atmospheric windows between 1.0 and 1.2 μm. These data can be used to determine information about surface properties on global scales. This requires a sophisticated approach to understand and consider the effects and interferences of different atmospheric and surface parameters influencing the retrieved values. In the present work, results of a new technique for retrieval of the 1.0 - 1.2 μm - surface emissivity are summarized. It includes a Multi-Window Retrieval Technique, a Multi-Spectrum Retrieval technique (MSR), and a detailed reliability analysis. The MWT bases on a detailed radiative transfer model making simultaneous use of information from different atmospheric windows of an individual spectrum. MSR regularizes the retrieval by incorporating available a priori mean values, standard deviations as well as spatial-temporal correlations of parameters to be retrieved. The capability of this method is shown for a selected surface target area. Implications for geologic investigations are discussed. Based on these results, the work draws conclusions for future Venus surface composition analyses on global scales using spectral remote sensing techniques. In that context, requirements for observational scenarios and instrumental performances are investigated, and recommendations are derived to optimize spectral measurements for Venus' surface studies.

On shock driven jetting of liquid from non-sinusoidal surfaces into a vacuum

DOE PAGES

Cherne, F. J.; Hammerberg, J. E.; Andrews, M. J.; ...

2015-11-09

Other work employed Richtmyer-Meshkov theory to describe the development of spikes and bubblesfrom shocked sinusoidal surfaces. Here, we discuss the effects of machining different two-dimensional shaped grooves in copper and examine the resulting flow of the material after being shocked into liquid on release. For these simulations, a high performance molecular dynamics code, SPaSM, was used with machined grooves of kh 0 = 1 and kh 0 = 1/8, where 2h 0 is the peak-to-valley height of the perturbation with wavelength λ, and k = 2π/λ. The surface morphologies studied include a Chevron, a Fly-Cut, a Square-Wave, and a Gaussian.more » Furthermore, we describe extensions to an existing ejecta source model that better captures the mass ejected from these surfaces. We also investigate the same profiles at length scales of order 1 cm for an idealized fluid equation of state using the FLASH continuum hydrodynamics code. Our findings indicate that the resulting mass can be scaled by the missing area of a sinusoidal curve with an effective wavelength, λeff , that has the same missing area. Finally, our extended ejecta mass formula works well for all the shapes considered and captures the corresponding time evolution and total mass.« less

Origin of low-frequency noise in pentacene field-effect transistors

NASA Astrophysics Data System (ADS)

Xu, Yong; Minari, Takeo; Tsukagoshi, Kazuhito; Chroboczek, Jan; Balestra, Francis; Ghibaudo, Gerard

2011-07-01

Measurements of power spectral density (PSD) of low-frequency noise (LFN) in pentacene field-effect transistors reveal the preponderance of a 1/ f-type PSD behavior with the amplitude varying as the squared transistor gain and increasing as the inverse of the gate surface area. Such features impose an interpretation of LFN by carrier number fluctuations model involving capture/release of charges on traps uniformly distributed over the gate surface. The surface slow trap density extracted by the noise analysis is close to the surface states density deduced independently from static I(V) data, which confirms the validity of the proposed LFN interpretation. Further, we found that the trap densities in bottom-contact (BC) devices were higher than in their top-contact (TC) counterparts, in agreement with observations of a poorer crystal structure of BC devices, in the contact regions in particular. At the highest bias the noise originating from the contact resistance is also shown to be a dominant component in the PSD, and it is well explained by the noise originating from a gate-voltage dependent contact resistance. A gate area scaling was also performed, and the good scaling and the dispersion at the highest bias confirm the validity of the applied carrier number fluctuations model and the predominant contact noise at high current intensities.

PSI Wide Area Product (WAP) for measuring Ground Surface Displacements at regional level for multi-hazards studies

NASA Astrophysics Data System (ADS)

Duro, Javier; Iglesias, Rubén; Blanco, Pablo; Albiol, David; Koudogbo, Fifamè

2015-04-01

The Wide Area Product (WAP) is a new interferometric product developed to provide measurement over large regions. Persistent Scatterers Interferometry (PSI) has largely proved their robust and precise performance in measuring ground surface deformation in different application domains. In this context, however, the accurate displacement estimation over large-scale areas (more than 10.000 km2) characterized by low magnitude motion gradients (3-5 mm/year), such as the ones induced by inter-seismic or Earth tidal effects, still remains an open issue. The main reason for that is the inclusion of low quality and more distant persistent scatterers in order to bridge low-quality areas, such as water bodies, crop areas and forested regions. This fact yields to spatial propagation errors on PSI integration process, poor estimation and compensation of the Atmospheric Phase Screen (APS) and the difficult to face residual long-wavelength phase patterns originated by orbit state vectors inaccuracies. Research work for generating a Wide Area Product of ground motion in preparation for the Sentinel-1 mission has been conducted in the last stages of Terrafirma as well as in other research programs. These developments propose technological updates for keeping the precision over large scale PSI analysis. Some of the updates are based on the use of external information, like meteorological models, and the employment of GNSS data for an improved calibration of large measurements. Usually, covering wide regions implies the processing over areas with a land use which is chiefly focused on livestock, horticulture, urbanization and forest. This represents an important challenge for providing continuous InSAR measurements and the application of advanced phase filtering strategies to enhance the coherence. The advanced PSI processing has been performed out over several areas, allowing a large scale analysis of tectonic patterns, and motion caused by multi-hazards as volcanic, landslide and flood. Several examples of the application of the PSI WAP to wide regions for measuring ground displacements related to different types of hazards, natural and human induced will be presented. The InSAR processing approach to measure accurate movements at local and large scales for allowing multi-hazard interpretation studies will also be discussed. The test areas will show deformations related to active faults systems, landslides in mountains slopes, ground compaction over underneath aquifers and movements in volcanic areas.

Atomistic simulations of contact area and conductance at nanoscale interfaces.

PubMed

Hu, Xiaoli; Martini, Ashlie

2017-11-09

Atomistic simulations were used to study conductance across the interface between a nanoscale gold probe and a graphite surface with a step edge. Conductance on the graphite terrace was observed to increase with load and be approximately proportional to contact area calculated from the positions of atoms in the interface. The relationship between area and conductance was further explored by varying the position of the contact relative to the location of the graphite step edge. These simulations reproduced a previously-reported current dip at step edges measured experimentally and the trend was explained by changes in both contact area and the distribution of distances between atoms in the interface. The novel approach reported here provides a foundation for future studies of the fundamental relationships between conductance, load and surface topography at the atomic scale.

Characterizing the fabric of the urban environment: A case study of Greater Houston, Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rose, Leanna Shea; Akbari, Hashem; Taha, Haider

2003-01-15

In this report, the materials and various surface types that comprise a city are referred to as the ''urban fabric.'' Urban fabric data are needed in order to estimate the impact of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city, and to design effective urban environmental implementation programs. We discuss the results of a semi-automatic Monte-Carlo statistical approach used to develop data on surface-type distribution and city-fabric makeup (percentage of various surface-types) using aerial color orthophotography. The digital aerial photographs for Houston covered a total of about 52more » km2 (20 mi2). At 0.30-m resolution, there were approximately 5.8 x 108 pixels of data. Four major land-use types were examined: (1) commercial, (2) industrial, (3) educational, and (4) residential. On average, for the regions studied, vegetation covers about 39 percent of the area, roofs cover about 21 percent, and paved surfaces cover about 29 percent. For the most part, trees shade streets, parking lots, grass, and sidewalks. At ground level, i.e., view from below the vegetation canopies, paved surfaces cover about 32 percent of the study area. GLOBEIS model data from University of Texas and land-use/land-cover (LULC) information from the United States Geological Survey (USGS) were used to extrapolate these results from neighborhood scales to Greater Houston. It was found that in an area of roughly 3,430 km2, defining most of Greater Houston, over 56 percent is residential. The total roof area is about 740 km2, and the total paved surface area (roads, parking areas, sidewalks) covers about 1000 km2. Vegetation covers about 1,320 km2.« less

Physics of microstructures enhancement of thin film evaporation heat transfer in microchannels flow boiling

PubMed Central

Bigham, Sajjad; Fazeli, Abdolreza; Moghaddam, Saeed

2017-01-01

Performance enhancement of the two-phase flow boiling heat transfer process in microchannels through implementation of surface micro- and nanostructures has gained substantial interest in recent years. However, the reported results range widely from a decline to improvements in performance depending on the test conditions and fluid properties, without a consensus on the physical mechanisms responsible for the observed behavior. This gap in knowledge stems from a lack of understanding of the physics of surface structures interactions with microscale heat and mass transfer events involved in the microchannel flow boiling process. Here, using a novel measurement technique, the heat and mass transfer process is analyzed within surface structures with unprecedented detail. The local heat flux and dryout time scale are measured as the liquid wicks through surface structures and evaporates. The physics governing heat transfer enhancement on textured surfaces is explained by a deterministic model that involves three key parameters: the drying time scale of the liquid film wicking into the surface structures (τd), the heating length scale of the liquid film (δH) and the area fraction of the evaporating liquid film (Ar). It is shown that the model accurately predicts the optimum spacing between surface structures (i.e. pillars fabricated on the microchannel wall) in boiling of two fluids FC-72 and water with fundamentally different wicking characteristics. PMID:28303952

Lunar surface magnetometer experiment

NASA Technical Reports Server (NTRS)

Dyal, P.; Parkin, C. W.; Colburn, D. S.; Schubert, G.

1972-01-01

The Apollo 16 lunar surface magnetometer (LSM) activation completed the network installation of magnetic observatories on the lunar surface and initiated simultaneous measurements of the global response of the moon to large-scale solar and terrestrial magnetic fields. Fossil remanent magnetic fields have been measured at nine locations on the lunar surface, including the Apollo 16 LSM site in the Descartes highlands area. This fossil record indicates the possible existence of an ancient lunar dynamo or a solar or terrestrial field much stronger than exists at present. The experimental technique and operation of the LSM are described and the results obtained are discussed.

Reliable solution processed planar perovskite hybrid solar cells with large-area uniformity by chloroform soaking and spin rinsing induced surface precipitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chern, Yann-Cherng; Wu, Hung-Ruei; Chen, Yen-Chu

2015-08-15

A solvent soaking and rinsing method, in which the solvent was allowed to soak all over the surface followed by a spinning for solvent draining, was found to produce perovskite layers with high uniformity on a centimeter scale and with much improved reliability. Besides the enhanced crystallinity and surface morphology due to the rinsing induced surface precipitation that constrains the grain growth underneath in the precursor films, large-area uniformity with film thickness determined exclusively by the rotational speed of rinsing spinning for solvent draining was observed. With chloroform as rinsing solvent, highly uniform and mirror-like perovskite layers of area asmore » large as 8 cm × 8 cm were produced and highly uniform planar perovskite solar cells with power conversion efficiency of 10.6 ± 0.2% as well as much prolonged lifetime were obtained. The high uniformity and reliability observed with this solvent soaking and rinsing method were ascribed to the low viscosity of chloroform as well as its feasibility of mixing with the solvent used in the precursor solution. Moreover, since the surface precipitation forms before the solvent draining, this solvent soaking and rinsing method may be adapted to spinless process and be compatible with large-area and continuous production. With the large-area uniformity and reliability for the resultant perovskite layers, this chloroform soaking and rinsing approach may thus be promising for the mass production and commercialization of large-area perovskite solar cells.« less

InSAR and GPS Time Series Analysis in Areas with Large Scale Hydrological Deformation: Separating Signal From Noise at Varying Length Scales in the San Joaquin Valley

NASA Astrophysics Data System (ADS)

Murray, K. D.; Lohman, R.

2017-12-01

Areas of large-scale subsidence are observed over much of the San Joaquin Valley of California due to the extraction of groundwater and hydrocarbons from the subsurface.These signals span regions with spatial extents of up to 100 km and have rates of up to 45 cm/yr or more. InSAR and GPS are complementary methods commonly used to measure such ground displacements and can provide important constraints on crustal deformation models, support groundwater studies, and inform water resource management efforts. However, current standard methods for processing these data sets and creating displacement time series are suboptimal for the deformation observed in areas like the San Joaquin Valley because (1) the ground surface properties are constantly changing due largely to agricultural activity, resulting in low coherence in half or more of a SAR frame, and (2) the deformation signals are distributed throughout the SAR frames, and are comparable to the size of the frames themselves. Therefore, referencing areas of deformation to non-deforming areas and correcting for long wavelength signals (e.g. atmospheric delays, orbital errors) is particularly difficult. We address these challenges by exploiting pixels that are stable in space and time, and use them for weighted spatial averaging and selective filtering before unwrapping. We then compare a range of methods for both long wavelength corrections and referencing via automatic partitioning of non-deforming areas, then benchmark results against continuous GPS measurements. Our final time series consist of nearly 15 years of displacement measurements from continuous GPS data, and Envisat, ALOS-1, Sentinel SAR data, and show significant temporal and spatial variations. We find that the choice of reference and long wavelength corrections can significantly bias long-term rate and seasonal amplitude estimates, causing variations of as much as 100% of the mean estimate. As we enter an era with free and open data access and regular observations plans from missions such as NISAR and the Sentinel constellation, our approach will help users evaluate the significance of observed deformation at a range of spatial scales and in areas with challenging surface properties.

The managed clearing: An overlooked land-cover type in urbanizing regions?

PubMed Central

Madden, Marguerite; Gray, Josh; Meentemeyer, Ross K.

2018-01-01

Urban ecosystem assessments increasingly rely on widely available map products, such as the U.S. Geological Service (USGS) National Land Cover Database (NLCD), and datasets that use generic classification schemes to detect and model large-scale impacts of land-cover change. However, utilizing existing map products or schemes without identifying relevant urban class types such as semi-natural, yet managed land areas that account for differences in ecological functions due to their pervious surfaces may severely constrain assessments. To address this gap, we introduce the managed clearings land-cover type–semi-natural, vegetated land surfaces with varying degrees of management practices–for urbanizing landscapes. We explore the extent to which managed clearings are common and spatially distributed in three rapidly urbanizing areas of the Charlanta megaregion, USA. We visually interpreted and mapped fine-scale land cover with special attention to managed clearings using 2012 U.S. Department of Agriculture (USDA) National Agriculture Imagery Program (NAIP) images within 150 randomly selected 1-km2 blocks in the cities of Atlanta, Charlotte, and Raleigh, and compared our maps with National Land Cover Database (NLCD) data. We estimated the abundance of managed clearings relative to other land use and land cover types, and the proportion of land-cover types in the NLCD that are similar to managed clearings. Our study reveals that managed clearings are the most common land cover type in these cities, covering 28% of the total sampled land area– 6.2% higher than the total area of impervious surfaces. Managed clearings, when combined with forest cover, constitutes 69% of pervious surfaces in the sampled region. We observed variability in area estimates of managed clearings between the NAIP-derived and NLCD data. This suggests using high-resolution remote sensing imagery (e.g., NAIP) instead of modifying NLCD data for improved representation of spatial heterogeneity and mapping of managed clearings in urbanizing landscapes. Our findings also demonstrate the need to more carefully consider managed clearings and their critical ecological functions in landscape- to regional-scale studies of urbanizing ecosystems. PMID:29432442

A new fractional snow-covered area parameterization for the Community Land Model and its effect on the surface energy balance

NASA Astrophysics Data System (ADS)

Swenson, S. C.; Lawrence, D. M.

2011-11-01

One function of the Community Land Model (CLM4) is the determination of surface albedo in the Community Earth System Model (CESM1). Because the typical spatial scales of CESM1 simulations are large compared to the scales of variability of surface properties such as snow cover and vegetation, unresolved surface heterogeneity is parameterized. Fractional snow-covered area, or snow-covered fraction (SCF), within a CLM4 grid cell is parameterized as a function of grid cell mean snow depth and snow density. This parameterization is based on an analysis of monthly averaged SCF and snow depth that showed a seasonal shift in the snow depth-SCF relationship. In this paper, we show that this shift is an artifact of the monthly sampling and that the current parameterization does not reflect the relationship observed between snow depth and SCF at the daily time scale. We demonstrate that the snow depth analysis used in the original study exhibits a bias toward early melt when compared to satellite-observed SCF. This bias results in a tendency to overestimate SCF as a function of snow depth. Using a more consistent, higher spatial and temporal resolution snow depth analysis reveals a clear hysteresis between snow accumulation and melt seasons. Here, a new SCF parameterization based on snow water equivalent is developed to capture the observed seasonal snow depth-SCF evolution. The effects of the new SCF parameterization on the surface energy budget are described. In CLM4, surface energy fluxes are calculated assuming a uniform snow cover. To more realistically simulate environments having patchy snow cover, we modify the model by computing the surface fluxes separately for snow-free and snow-covered fractions of a grid cell. In this configuration, the form of the parameterized snow depth-SCF relationship is shown to greatly affect the surface energy budget. The direct exposure of the snow-free surfaces to the atmosphere leads to greater heat loss from the ground during autumn and greater heat gain during spring. The net effect is to reduce annual mean soil temperatures by up to 3°C in snow-affected regions.

A new fractional snow-covered area parameterization for the Community Land Model and its effect on the surface energy balance

NASA Astrophysics Data System (ADS)

Swenson, S. C.; Lawrence, D. M.

2012-11-01

One function of the Community Land Model (CLM4) is the determination of surface albedo in the Community Earth System Model (CESM1). Because the typical spatial scales of CESM1 simulations are large compared to the scales of variability of surface properties such as snow cover and vegetation, unresolved surface heterogeneity is parameterized. Fractional snow-covered area, or snow-covered fraction (SCF), within a CLM4 grid cell is parameterized as a function of grid cell mean snow depth and snow density. This parameterization is based on an analysis of monthly averaged SCF and snow depth that showed a seasonal shift in the snow depth-SCF relationship. In this paper, we show that this shift is an artifact of the monthly sampling and that the current parameterization does not reflect the relationship observed between snow depth and SCF at the daily time scale. We demonstrate that the snow depth analysis used in the original study exhibits a bias toward early melt when compared to satellite-observed SCF. This bias results in a tendency to overestimate SCF as a function of snow depth. Using a more consistent, higher spatial and temporal resolution snow depth analysis reveals a clear hysteresis between snow accumulation and melt seasons. Here, a new SCF parameterization based on snow water equivalent is developed to capture the observed seasonal snow depth-SCF evolution. The effects of the new SCF parameterization on the surface energy budget are described. In CLM4, surface energy fluxes are calculated assuming a uniform snow cover. To more realistically simulate environments having patchy snow cover, we modify the model by computing the surface fluxes separately for snow-free and snow-covered fractions of a grid cell. In this configuration, the form of the parameterized snow depth-SCF relationship is shown to greatly affect the surface energy budget. The direct exposure of the snow-free surfaces to the atmosphere leads to greater heat loss from the ground during autumn and greater heat gain during spring. The net effect is to reduce annual mean soil temperatures by up to 3°C in snow-affected regions.

Allometric scaling of infraorbital surface topography in Homo.

PubMed

Maddux, Scott D; Franciscus, Robert G

2009-02-01

Infraorbital morphology is often included in phylogenetic and functional analyses of Homo. The inclusion of distinct infraorbital configurations, such as the "canine fossa" in Homo sapiens or the "inflated" maxilla in Neandertals, is generally based on either descriptive or qualitative assessments of this morphology, or simple linear chord and subtense measurements. However, the complex curvilinear surface of the infraorbital region has proven difficult to quantify through these traditional methods. In this study, we assess infraorbital shape and its potential allometric scaling in fossil Homo (n=18) and recent humans (n=110) with a geometric morphometric method well-suited for quantifying complex surface topographies. Our results indicate that important aspects of infraorbital shape are correlated with overall infraorbital size across Homo. Specifically, individuals with larger infraorbital areas tend to exhibit relatively flatter infraorbital surface topographies, taller and narrower infraorbital areas, sloped inferior orbital rims, anteroinferiorly oriented maxillary body facies, posteroinferiorly oriented maxillary processes of the zygomatic, and non-everted lateral nasal margins. In contrast, individuals with smaller infraorbital regions generally exhibit relatively depressed surface topographies, shorter and wider infraorbital areas, projecting inferior orbital rims, posteroinferiorly oriented maxillary body facies, anteroinferiorly oriented maxillary processes, and everted lateral nasal margins. These contrasts form a continuum and only appear dichotomized at the ends of the infraorbital size spectrum. In light of these results, we question the utility of incorporating traditionally polarized infraorbital morphologies in phylogenetic and functional analyses without due consideration of continuous infraorbital and facial size variation in Homo. We conclude that the essentially flat infraorbital surface topography of Neandertals is not unique and can be explained, in part, as a function of possessing large infraorbital regions, the ancestral condition for Homo. Furthermore, it appears likely that the diminutive infraorbital region of anatomically modern Homo sapiens is a primary derived trait, with related features such as depressed infraorbital surface topography expressed as correlated secondary characters.

Heat transfer from an oxidized large copper surface to liquid helium: Dependence on surface orientation and treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iwamoto, A.; Mito, T.; Takahata, K.

Heat transfer of large copper plates (18 x 76 mm) in liquid helium has been measured as a function of orientation and treatment of the heat transfer surface. The results relate to applications of large scale superconductors. In order to clarify the influence of the area where the surface treatment peels off, the authors studied five types of heat transfer surface areas including: (a) 100% polished copper sample, (b) and (c) two 50% oxidized copper samples having different patterns of oxidation, (d) 75% oxidized copper sample, (e) 90% oxidized copper sample, and (f) 100% oxidized copper sample. They observed thatmore » the critical heat flux depends on the heat transfer surface orientation. The critical heat flux is a maximum at angles of 0{degrees} - 30{degrees} and decreases monotonically with increasing angles above 30{degrees}, where the angle is taken in reference to the horizontal axis. On the other hand, the minimum heat flux is less dependent on the surface orientation. More than 75% oxidation on the surface makes the critical heat flux increase. The minimum heat fluxes of the 50 and 90% oxidized Cu samples approximately agree with that of the 100% oxidized Cu sample. Experiments and calculations show that the critical and the minimum heat fluxes are a bilinear function of the fraction of oxidized surface area.« less

USACE Extreme Sea Levels Advice on Guidance on Procedures to Evaluate and Adapt to Changes in Mean and Extreme Sea Levels.

DTIC Science & Technology

2014-09-09

influences of changes in extreme sea levels as they affect the four mission areas of USACE: storm damage reduction, flood risk mitigation, ecosystems...winds and surface pressure can occur on the scale of the inundation area under investigation, cyclonic climatologies and more sophisticated inundation...Federal and State agencies (particularly the Bureau of Meteorology) providing forecast data (e.g. DIPNR, 2005, Appendix N). In more developed areas of

Utility of a Two-source Energy Balance Approach for Daily Mapping of Landsat-scale Fluxes Over Irrigated Agriculture in a Desert Environment

NASA Astrophysics Data System (ADS)

Houborg, R.; McCabe, M. F.; Rosas Aguilar, J.; Anderson, M. C.; Hain, C.

2014-12-01

The Middle East and North Africa (MENA) region is an area characterized by limited fresh water resources, an often inefficient use of these, and relatively poor in-situ monitoring as a result of sparse meteorological observations. Enhanced satellite-based monitoring systems are needed for aiding local water resource and agricultural management activities in these data poor arid environments. A multi-sensor and multi-scale land-surface flux monitoring capacity is being implemented over parts of MENA in order to provide meaningful decision support at relevant spatiotemporal scales. The integrated modeling system uses the Atmosphere-Land Exchange Inverse (ALEXI) model and associated flux disaggregation scheme (DisALEXI), and the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) in conjunction with model reanalysis data and remotely sensed data from polar orbiting (Landsat and MODIS; MODerate resolution Imaging Spectroradiometer) and geostationary (MSG; Meteosat Second Generation) satellite platforms to facilitate daily estimates of land surface fluxes down to sub-field scale (i.e. 30 m). Within this modeling system, thermal infrared satellite data provide information about the sub-surface moisture status and plant stress, obviating the need for precipitation input and error-prone soil surface characterizations. In this study, the integrated ALEXI-DisALEXI-STARFM framework is applied over an irrigated agricultural region in Saudi Arabia, and the daily estimates of Landsat scale water, energy and carbon fluxes are evaluated against available flux tower observations and other independent in-situ and satellite-based records. The study addresses the challenges associated with time-continuous sub-field scale mapping of land-surface fluxes in a harsh desert environment, and looks into the optimization of model descriptions and parameterizations and meteorological forcing and vegetation inputs for application over these regions.

Qualitatively Modeling solute fate and transport across scales in an agricultural catchment with diverse lithology

NASA Astrophysics Data System (ADS)

Wayman, C. R.; Russo, T. A.; Li, L.; Forsythe, B.; Hoagland, B.

2017-12-01

As part of the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) project, we have collected geochemical and hydrological data from several subcatchments and four monitoring sites on the main stem of Shaver's Creek, in Huntingon county, Pennsylvania. One subcatchment (0.43 km2) is under agricultural land use, and the monitoring locations on the larger Shaver's Creek (up to 163 km2) drain watersheds with 0 to 25% agricultural area. These two scales of investigation, coupled with advances made across the SSHCZO on multiple lithologies allow us to extrapolate from the subcatchment to the larger watershed. We use geochemical surface and groundwater data to estimate the solute and water transport regimes within the catchment, and to show how lithology and land use are major controls on ground and surface water quality. One area of investigation includes the transport of nutrients between interflow and regional groundwater, and how that connectivity may be reflected in local surface waters. Water and nutrient (Nitrogen) isotopes, will be used to better understand the relative contributions of local and regional groundwater and interflow fluxes into nearby streams. Following initial qualitative modeling, multiple hydrologic and nutrient transport models (e.g. SWAT and CYCLES/PIHM) will be evaluated from the subcatchment to large watershed scales. We will evaluate the ability to simulate the contributions of regional groundwater versus local groundwater, and also impacts of agricultural land management on surface water quality. Improving estimations of groundwater contributions to stream discharge will provide insight into how much agricultural development can impact stream quality and nutrient loading.

Clay mineral continental amplifier for marine carbon sequestration in a greenhouse ocean.

PubMed

Kennedy, Martin J; Wagner, Thomas

2011-06-14

The majority of carbon sequestration at the Earth's surface occurs in marine continental margin settings within fine-grained sediments whose mineral properties are a function of continental climatic conditions. We report very high mineral surface area (MSA) values of 300 and 570 m(2) g in Late Cretaceous black shales from Ocean Drilling Program site 959 of the Deep Ivorian Basin that vary on subcentennial time scales corresponding with abrupt increases from approximately 3 to approximately 18% total organic carbon (TOC). The observed MSA changes with TOC across multiple scales of variability and on a sample-by-sample basis (centimeter scale), provides a rigorous test of a hypothesized influence on organic carbon burial by detrital clay mineral controlled MSA. Changes in TOC also correspond with geochemical and sedimentological evidence for water column anoxia. Bioturbated intervals show a lower organic carbon loading on mineral surface area of 0.1 mg-OC m(-2) when compared to 0.4 mg-OC m(-2) for laminated and sulfidic sediments. Although either anoxia or mineral surface protection may be capable of producing TOC of < 5%, when brought together they produced the very high TOC (10-18%) apparent in these sediments. This nonlinear response in carbon burial resulted from minor precession-driven changes of continental climate influencing clay mineral properties and runoff from the African continent. This study identifies a previously unrecognized land-sea connection among continental weathering, clay mineral production, and anoxia and a nonlinear effect on marine carbon sequestration during the Coniacian-Santonian Oceanic Anoxic Event 3 in the tropical eastern Atlantic.

Beyond-laboratory-scale prediction for channeling flows through subsurface rock fractures with heterogeneous aperture distributions revealed by laboratory evaluation

NASA Astrophysics Data System (ADS)

Ishibashi, Takuya; Watanabe, Noriaki; Hirano, Nobuo; Okamoto, Atsushi; Tsuchiya, Noriyoshi

2015-01-01

The present study evaluates aperture distributions and fluid flow characteristics for variously sized laboratory-scale granite fractures under confining stress. As a significant result of the laboratory investigation, the contact area in fracture plane was found to be virtually independent of scale. By combining this characteristic with the self-affine fractal nature of fracture surfaces, a novel method for predicting fracture aperture distributions beyond laboratory scale is developed. Validity of this method is revealed through reproduction of the results of laboratory investigation and the maximum aperture-fracture length relations, which are reported in the literature, for natural fractures. The present study finally predicts conceivable scale dependencies of fluid flows through joints (fractures without shear displacement) and faults (fractures with shear displacement). Both joint and fault aperture distributions are characterized by a scale-independent contact area, a scale-dependent geometric mean, and a scale-independent geometric standard deviation of aperture. The contact areas for joints and faults are approximately 60% and 40%. Changes in the geometric means of joint and fault apertures (µm), em, joint and em, fault, with fracture length (m), l, are approximated by em, joint = 1 × 102 l0.1 and em, fault = 1 × 103 l0.7, whereas the geometric standard deviations of both joint and fault apertures are approximately 3. Fluid flows through both joints and faults are characterized by formations of preferential flow paths (i.e., channeling flows) with scale-independent flow areas of approximately 10%, whereas the joint and fault permeabilities (m2), kjoint and kfault, are scale dependent and are approximated as kjoint = 1 × 10-12 l0.2 and kfault = 1 × 10-8 l1.1.

Associating Land Surface Temperature Retrieved From Satellite and Unmanned Aerial Vehicle Data With Urban Cover and Topography in Aburrá Valley

NASA Astrophysics Data System (ADS)

Guzmán, G.; Hoyos Ortiz, C. D.

2017-12-01

Urban heat island effect commonly refers to temperature differences between urban areas and their countrysides due to urbanization. These temperature differences are evident at surface, and within the canopy and the boundary layer. This effect is heterogeneous within the city, and responds to urban morphology, prevailing materials, amount of vegetation, among others, which are also important in the urban balance of energy. In order to study the relationship between land surface temperature (LST) and urban coverage over Aburrá Valley, which is a narrow valley locate at tropical Andes in northern South America, Landsat 8 mission products of LST, density of vegetation (normalized difference vegetation index, NDVI), and a proxy of soil humidity are derived and used. The results are analyzed from the point of view of dominant urban form and settlement density at scale of neighborhoods, and also from potential downward solar radiation received at the surface. Besides, specific sites were chosen to obtain LST from thermal imaging using an unmanned aerial vehicle to characterize micro-scale patterns and to validate Landast retrievals. Direct relationships between LST, NDVI, soil humidity, and duration of insolation are found, showing the impact of the current spatial distribution of land uses on surface temperature over Aburrá Valley. In general, the highest temperatures correspond to neighborhoods with large, flat-topped buildings in commercial and industrial areas, and low-rise building in residential areas with scarce vegetation, all on the valley bottom. Landsat images are in the morning for the Aburrá Valley, for that reason the coldest temperatures are prevalent at certain orientation of the hillslope, according with the amount of radiation received from sunrise to time of data.

Scales of Spatial Heterogeneity of Plastic Marine Debris in the Northeast Pacific Ocean

PubMed Central

Goldstein, Miriam C.; Titmus, Andrew J.; Ford, Michael

2013-01-01

Plastic debris has been documented in many marine ecosystems, including remote coastlines, the water column, the deep sea, and subtropical gyres. The North Pacific Subtropical Gyre (NPSG), colloquially called the “Great Pacific Garbage Patch,” has been an area of particular scientific and public concern. However, quantitative assessments of the extent and variability of plastic in the NPSG have been limited. Here, we quantify the distribution, abundance, and size of plastic in a subset of the eastern Pacific (approximately 20–40°N, 120–155°W) over multiple spatial scales. Samples were collected in Summer 2009 using surface and subsurface plankton net tows and quantitative visual observations, and Fall 2010 using surface net tows only. We documented widespread, though spatially variable, plastic pollution in this portion of the NPSG and adjacent waters. The overall median microplastic numerical concentration in Summer 2009 was 0.448 particles m−2 and in Fall 2010 was 0.021 particles m−2, but plastic concentrations were highly variable over the submesoscale (10 s of km). Size-frequency spectra were skewed towards small particles, with the most abundant particles having a cross-sectional area of approximately 0.01 cm2. Most microplastic was found on the sea surface, with the highest densities detected in low-wind conditions. The numerical majority of objects were small particles collected with nets, but the majority of debris surface area was found in large objects assessed visually. Our ability to detect high-plastic areas varied with methodology, as stations with substantial microplastic did not necessarily also contain large visually observable objects. A power analysis of our data suggests that high variability of surface microplastic will make future changes in abundance difficult to detect without substantial sampling effort. Our findings suggest that assessment and monitoring of oceanic plastic debris must account for high spatial variability, particularly in regards to the evaluation of initiatives designed to reduce marine debris. PMID:24278233

Scales of spatial heterogeneity of plastic marine debris in the northeast pacific ocean.

PubMed

Goldstein, Miriam C; Titmus, Andrew J; Ford, Michael

2013-01-01

Plastic debris has been documented in many marine ecosystems, including remote coastlines, the water column, the deep sea, and subtropical gyres. The North Pacific Subtropical Gyre (NPSG), colloquially called the "Great Pacific Garbage Patch," has been an area of particular scientific and public concern. However, quantitative assessments of the extent and variability of plastic in the NPSG have been limited. Here, we quantify the distribution, abundance, and size of plastic in a subset of the eastern Pacific (approximately 20-40°N, 120-155°W) over multiple spatial scales. Samples were collected in Summer 2009 using surface and subsurface plankton net tows and quantitative visual observations, and Fall 2010 using surface net tows only. We documented widespread, though spatially variable, plastic pollution in this portion of the NPSG and adjacent waters. The overall median microplastic numerical concentration in Summer 2009 was 0.448 particles m(-2) and in Fall 2010 was 0.021 particles m(-2), but plastic concentrations were highly variable over the submesoscale (10 s of km). Size-frequency spectra were skewed towards small particles, with the most abundant particles having a cross-sectional area of approximately 0.01 cm(2). Most microplastic was found on the sea surface, with the highest densities detected in low-wind conditions. The numerical majority of objects were small particles collected with nets, but the majority of debris surface area was found in large objects assessed visually. Our ability to detect high-plastic areas varied with methodology, as stations with substantial microplastic did not necessarily also contain large visually observable objects. A power analysis of our data suggests that high variability of surface microplastic will make future changes in abundance difficult to detect without substantial sampling effort. Our findings suggest that assessment and monitoring of oceanic plastic debris must account for high spatial variability, particularly in regards to the evaluation of initiatives designed to reduce marine debris.

Color analysis and image rendering of woodblock prints with oil-based ink

NASA Astrophysics Data System (ADS)

Horiuchi, Takahiko; Tanimoto, Tetsushi; Tominaga, Shoji

2012-01-01

This paper proposes a method for analyzing the color characteristics of woodblock prints having oil-based ink and rendering realistic images based on camera data. The analysis results of woodblock prints show some characteristic features in comparison with oil paintings: 1) A woodblock print can be divided into several cluster areas, each with similar surface spectral reflectance; and 2) strong specular reflection from the influence of overlapping paints arises only in specific cluster areas. By considering these properties, we develop an effective rendering algorithm by modifying our previous algorithm for oil paintings. A set of surface spectral reflectances of a woodblock print is represented by using only a small number of average surface spectral reflectances and the registered scaling coefficients, whereas the previous algorithm for oil paintings required surface spectral reflectances of high dimension at all pixels. In the rendering process, in order to reproduce the strong specular reflection in specific cluster areas, we use two sets of parameters in the Torrance-Sparrow model for cluster areas with or without strong specular reflection. An experiment on a woodblock printing with oil-based ink was performed to demonstrate the feasibility of the proposed method.

Research note: Mapping spatial patterns in sewer age, material, and proximity to surface waterways to infer sewer leakage hotspots

USGS Publications Warehouse

Hopkins, Kristina G.; Bain, Daniel J.

2018-01-01

Identifying areas where deteriorating sewer infrastructure is in close proximity to surface waterways is needed to map likely connections between sewers and streams. We present a method to estimate sewer installation year and deterioration status using historical maps of the sewer network, parcel-scale property assessment data, and pipe material. Areas where streams were likely buried into the sewer system were mapped by intersecting the historical stream network derived from a 10-m resolution digital elevation model with sewer pipe locations. Potential sewer leakage hotspots were mapped by identifying where aging sewer pipes are in close proximity (50-m) to surface waterways. Results from Pittsburgh, Pennsylvania (USA), indicated 41% of the historical stream length was lost or buried and the potential interface between sewers and streams is great. The co-location of aging sewer infrastructure (>75 years old) near stream channels suggests that 42% of existing streams are located in areas with a high potential for sewer leakage if sewer infrastructure fails. Mapping the sewer-stream interface provides an approach to better understand areas were failing sewers may contribute a disproportional amount of nutrients and other pathogens to surface waterways.

Mapping surface heat fluxes by assimilating GOES land surface temperature and SMAP products

NASA Astrophysics Data System (ADS)

Lu, Y.; Steele-Dunne, S. C.; Van De Giesen, N.

2017-12-01

Surface heat fluxes significantly affect the land-atmosphere interaction, but their modelling is often hindered by the lack of in-situ measurements and the high spatial heterogeneity. Here, we propose a hybrid particle assimilation strategy to estimate surface heat fluxes by assimilating GOES land surface temperature (LST) data and SMAP products into a simple dual-source surface energy balance model, in which the requirement for in-situ data is minimized. The study aims to estimate two key parameters: a neutral bulk heat transfer coefficient (CHN) and an evaporative fraction (EF). CHN scales the sum of surface energy fluxes, and EF represents the partitioning between flux components. To bridge the huge resolution gap between GOES and SMAP data, SMAP data are assimilated using a particle filter to update soil moisture which constrains EF, and GOES data are assimilated with an adaptive particle batch smoother to update CHN. The methodology is applied to an area in the US Southern Great Plains with forcing data from NLDAS-2 and the GPM mission. Assessment against in-situ observations suggests that the sensible and latent heat flux estimates are greatly improved at both daytime and 30-min scale after assimilation, particularly for latent heat fluxes. Comparison against an LST-only assimilation case demonstrates that despite the coarse resolution, assimilating SMAP data is not only beneficial but also crucial for successful and robust flux estimation, particularly when the modelling uncertainties are large. Since the methodology is independent on in-situ data, it can be easily applied to other areas.

Data-based discharge extrapolation: estimating annual discharge for a partially gauged large river basin from its small sub-basins

NASA Astrophysics Data System (ADS)

Gong, L.

2013-12-01

Large-scale hydrological models and land surface models are by far the only tools for accessing future water resources in climate change impact studies. Those models estimate discharge with large uncertainties, due to the complex interaction between climate and hydrology, the limited quality and availability of data, as well as model uncertainties. A new purely data-based scale-extrapolation method is proposed, to estimate water resources for a large basin solely from selected small sub-basins, which are typically two-orders-of-magnitude smaller than the large basin. Those small sub-basins contain sufficient information, not only on climate and land surface, but also on hydrological characteristics for the large basin In the Baltic Sea drainage basin, best discharge estimation for the gauged area was achieved with sub-basins that cover 2-4% of the gauged area. There exist multiple sets of sub-basins that resemble the climate and hydrology of the basin equally well. Those multiple sets estimate annual discharge for gauged area consistently well with 5% average error. The scale-extrapolation method is completely data-based; therefore it does not force any modelling error into the prediction. The multiple predictions are expected to bracket the inherent variations and uncertainties of the climate and hydrology of the basin. The method can be applied in both un-gauged basins and un-gauged periods with uncertainty estimation.

Contemporary and restorable wetland water storage: A landscape perspective

USDA-ARS?s Scientific Manuscript database

Surface water storage in wetlands drives ecosystem function from local to landscape scales. In many regions, hydrologic modifications have significantly reduced wetland storage capacity and subsequently diminished wetland functions. While the loss of wetland area has been well documented across many...

An evaluation of the spatial resolution of soil moisture information

NASA Technical Reports Server (NTRS)

Hardy, K. R.; Cohen, S. H.; Rogers, L. K.; Burke, H. H. K.; Leupold, R. C.; Smallwood, M. D.

1981-01-01

Rainfall-amount patterns in the central regions of the U.S. were assessed. The spatial scales of surface features and their corresponding microwave responses in the mid western U.S. were investigated. The usefulness for U.S. government agencies of soil moisture information at scales of 10 km and 1 km. was ascertained. From an investigation of 494 storms, it was found that the rainfall resulting from the passage of most types of storms produces patterns which can be resolved on a 10 km scale. The land features causing the greatest problem in the sensing of soil moisture over large agricultural areas with a radiometer are bodies of water. Over the mid-western portions of the U.S., water occupies less than 2% of the total area, the consequently, the water bodies will not have a significant impact on the mapping of soil moisture. Over most of the areas, measurements at a 10-km resolution would adequately define the distribution of soil moisture. Crop yield models and hydrological models would give improved results if soil moisture information at scales of 10 km was available.

Statistical scaling of geometric characteristics in stochastically generated pore microstructures

DOE PAGES

Hyman, Jeffrey D.; Guadagnini, Alberto; Winter, C. Larrabee

2015-05-21

In this study, we analyze the statistical scaling of structural attributes of virtual porous microstructures that are stochastically generated by thresholding Gaussian random fields. Characterization of the extent at which randomly generated pore spaces can be considered as representative of a particular rock sample depends on the metrics employed to compare the virtual sample against its physical counterpart. Typically, comparisons against features and/patterns of geometric observables, e.g., porosity and specific surface area, flow-related macroscopic parameters, e.g., permeability, or autocorrelation functions are used to assess the representativeness of a virtual sample, and thereby the quality of the generation method. Here, wemore » rely on manifestations of statistical scaling of geometric observables which were recently observed in real millimeter scale rock samples [13] as additional relevant metrics by which to characterize a virtual sample. We explore the statistical scaling of two geometric observables, namely porosity (Φ) and specific surface area (SSA), of porous microstructures generated using the method of Smolarkiewicz and Winter [42] and Hyman and Winter [22]. Our results suggest that the method can produce virtual pore space samples displaying the symptoms of statistical scaling observed in real rock samples. Order q sample structure functions (statistical moments of absolute increments) of Φ and SSA scale as a power of the separation distance (lag) over a range of lags, and extended self-similarity (linear relationship between log structure functions of successive orders) appears to be an intrinsic property of the generated media. The width of the range of lags where power-law scaling is observed and the Hurst coefficient associated with the variables we consider can be controlled by the generation parameters of the method.« less

How Much Global Burned Area Can Be Forecast on Seasonal Time Scales Using Sea Surface Temperatures?

NASA Technical Reports Server (NTRS)

Chen, Yang; Morton, Douglas C.; Andela, Niels; Giglio, Louis; Randerson, James T.

2016-01-01

Large-scale sea surface temperature (SST) patterns influence the interannual variability of burned area in many regions by means of climate controls on fuel continuity, amount, and moisture content. Some of the variability in burned area is predictable on seasonal timescales because fuel characteristics respond to the cumulative effects of climate prior to the onset of the fire season. Here we systematically evaluated the degree to which annual burned area from the Global Fire Emissions Database version 4 with small fires (GFED4s) can be predicted using SSTs from 14 different ocean regions. We found that about 48 of global burned area can be forecast with a correlation coefficient that is significant at a p < 0.01 level using a single ocean climate index (OCI) 3 or more months prior to the month of peak burning. Continental regions where burned area had a higher degree of predictability included equatorial Asia, where 92% of the burned area exceeded the correlation threshold, and Central America, where 86% of the burned area exceeded this threshold. Pacific Ocean indices describing the El Nino-Southern Oscillation were more important than indices from other ocean basins, accounting for about 1/3 of the total predictable global burned area. A model that combined two indices from different oceans considerably improved model performance, suggesting that fires in many regions respond to forcing from more than one ocean basin. Using OCI-burned area relationships and a clustering algorithm, we identified 12 hotspot regions in which fires had a consistent response to SST patterns. Annual burned area in these regions can be predicted with moderate confidence levels, suggesting operational forecasts may be possible with the aim of improving ecosystem management.

Comparison of SLAR images and small-scale, low-sun aerial photographs.

NASA Technical Reports Server (NTRS)

Clark, M. M.

1971-01-01

A comparison of side-looking airborne radar (SLAR) images and black and white aerial photos of similar scale and illumination of an area in the Mojave Desert of California shows that aerial photos yield far more information about geology than do SLAR images because of greater resolution, tonal range, and geometric fidelity, and easier use in stereo. Nevertheless, radar can differentiate some materials or surfaces that aerial photos cannot; thus, they should be considered as complementary, rather than competing tools in geologic investigations. The most significant advantage of SLAR, however, is its freedom from the stringent conditions of weather, date, and time that are required by small-scale aerial photos taken with a specified direction and angle of illumination. Indeed, in low latitudes, SLAR is the only way to obtain small-scale images with low illumination from certain directions; moreover, in areas of nearly continuous cloudiness, radar may be the only practical source of small-scale images.

Patterns and scaling properties of surface soil moisture in an agricultural landscape: An ecohydrological modeling study

NASA Astrophysics Data System (ADS)

Korres, W.; Reichenau, T. G.; Schneider, K.

2013-08-01

Soil moisture is a key variable in hydrology, meteorology and agriculture. Soil moisture, and surface soil moisture in particular, is highly variable in space and time. Its spatial and temporal patterns in agricultural landscapes are affected by multiple natural (precipitation, soil, topography, etc.) and agro-economic (soil management, fertilization, etc.) factors, making it difficult to identify unequivocal cause and effect relationships between soil moisture and its driving variables. The goal of this study is to characterize and analyze the spatial and temporal patterns of surface soil moisture (top 20 cm) in an intensively used agricultural landscape (1100 km2 northern part of the Rur catchment, Western Germany) and to determine the dominant factors and underlying processes controlling these patterns. A second goal is to analyze the scaling behavior of surface soil moisture patterns in order to investigate how spatial scale affects spatial patterns. To achieve these goals, a dynamically coupled, process-based and spatially distributed ecohydrological model was used to analyze the key processes as well as their interactions and feedbacks. The model was validated for two growing seasons for the three main crops in the investigation area: Winter wheat, sugar beet, and maize. This yielded RMSE values for surface soil moisture between 1.8 and 7.8 vol.% and average RMSE values for all three crops of 0.27 kg m-2 for total aboveground biomass and 0.93 for green LAI. Large deviations of measured and modeled soil moisture can be explained by a change of the infiltration properties towards the end of the growing season, especially in maize fields. The validated model was used to generate daily surface soil moisture maps, serving as a basis for an autocorrelation analysis of spatial patterns and scale. Outside of the growing season, surface soil moisture patterns at all spatial scales depend mainly upon soil properties. Within the main growing season, larger scale patterns that are induced by soil properties are superimposed by the small scale land use pattern and the resulting small scale variability of evapotranspiration. However, this influence decreases at larger spatial scales. Most precipitation events cause temporarily higher surface soil moisture autocorrelation lengths at all spatial scales for a short time even beyond the autocorrelation lengths induced by soil properties. The relation of daily spatial variance to the spatial scale of the analysis fits a power law scaling function, with negative values of the scaling exponent, indicating a decrease in spatial variability with increasing spatial resolution. High evapotranspiration rates cause an increase in the small scale soil moisture variability, thus leading to large negative values of the scaling exponent. Utilizing a multiple regression analysis, we found that 53% of the variance of the scaling exponent can be explained by a combination of an independent LAI parameter and the antecedent precipitation.

Submicron structures provide preferential spots for carbon and nitrogen sequestration in soils

PubMed Central

Vogel, Cordula; Mueller, Carsten W.; Höschen, Carmen; Buegger, Franz; Heister, Katja; Schulz, Stefanie; Schloter, Michael; Kögel-Knabner, Ingrid

2014-01-01

The sequestration of carbon and nitrogen by clay-sized particles in soils is well established, and clay content or mineral surface area has been used to estimate the sequestration potential of soils. Here, via incubation of a sieved (<2 mm) topsoil with labelled litter, we find that only some of the clay-sized surfaces bind organic matter (OM). Surprisingly, <19% of the visible mineral areas show an OM attachment. OM is preferentially associated with organo-mineral clusters with rough surfaces. By combining nano-scale secondary ion mass spectrometry and isotopic tracing, we distinguish between new labelled and pre-existing OM and show that new OM is preferentially attached to already present organo-mineral clusters. These results, which provide evidence that only a limited proportion of the clay-sized surfaces contribute to OM sequestration, revolutionize our view of carbon sequestration in soils and the widely used carbon saturation estimates. PMID:24399306

Evapotranspiration and runoff from large land areas: Land surface hydrology for atmospheric general circulation models

NASA Technical Reports Server (NTRS)

Famiglietti, J. S.; Wood, Eric F.

1993-01-01

A land surface hydrology parameterization for use in atmospheric GCM's is presented. The parameterization incorporates subgrid scale variability in topography, soils, soil moisture and precipitation. The framework of the model is the statistical distribution of a topography-soils index, which controls the local water balance fluxes, and is therefore taken to represent the large land area. Spatially variable water balance fluxes are integrated with respect to the topography-soils index to yield our large topography-soils distribution, and interval responses are weighted by the probability of occurrence of the interval. Grid square averaged land surface fluxes result. The model functions independently as a macroscale water balance model. Runoff ratio and evapotranspiration efficiency parameterizations are derived and are shown to depend on the spatial variability of the above mentioned properties and processes, as well as the dynamics of land surface-atmosphere interactions.

Echelon approach to areas of concern in synoptic regional monitoring

USGS Publications Warehouse

Myers, Wayne; Patil, Ganapati P.; Joly, Kyle

1997-01-01

Echelons provide an objective approach to prospecting for areas of potential concern in synoptic regional monitoring of a surface variable. Echelons can be regarded informally as stacked hill forms. The strategy is to identify regions of the surface which are elevated relative to surroundings (Relative ELEVATIONS or RELEVATIONS). These are areas which would continue to expand as islands with receding (virtual) floodwaters. Levels where islands would merge are critical elevations which delimit echelons in the vertical dimension. Families of echelons consist of surface sectors constituting separate islands for deeper waters that merge as water level declines. Pits which would hold water are disregarded in such a progression, but a complementary analysis of pits is obtained using the surface as a virtual mould to cast a counter-surface (bathymetric analysis). An echelon tree is a family tree of echelons with peaks as terminals and the lowest level as root. An echelon tree thus provides a dendrogram representation of surface topology which enables graph theoretic analysis and comparison of surface structures. Echelon top view maps show echelon cover sectors on the base plane. An echelon table summarizes characteristics of echelons as instances or cases of hill form surface structure. Determination of echelons requires only ordinal strength for the surface variable, and is thus appropriate for environmental indices as well as measurements. Since echelons are inherent in a surface rather than perceptual, they provide a basis for computer-intelligent understanding of surfaces. Echelons are given for broad-scale mammalian species richness in Pennsylvania.

Testing deep-sea biodiversity paradigms on abyssal nematode genera and Acantholaimus species

NASA Astrophysics Data System (ADS)

Lins, Lidia; da Silva, Maria Cristina; Neres, Patrícia; Esteves, André Morgado; Vanreusel, Ann

2018-02-01

Biodiversity patterns in the deep sea have been extensively studied in the last decades. In this study, we investigated whether reputable concepts in deep-sea ecology also explain diversity and distribution patterns of nematode genera and species in the abyss. Among them, three paradigms were tackled: (1) the deep sea is a highly diverse environment at a local scale, while on a regional and even larger geographical scale, species and genus turnover is limited; (2) the biodiversity of deep-sea nematode communities changes with the nature and amount of organic matter input from the surface; and (3) patch-mosaic dynamics of the deep-sea environment drive local diversity. To test these hypotheses, diversity and density of nematode assemblages and of species of the genus Acantholaimus were studied along two abyssal E-W transects. These two transects were situated in the Southern Ocean ( 50°S) and the North Atlantic ( 10°N). Four different hierarchical scales were used to compare biodiversity: at the scale of cores, between stations from the same region, and between regions. Results revealed that the deep sea harbours a high diversity at a local scale (alpha diversity), but that turnover can be shaped by different environmental drivers. Therefore, these results question the second part of the paradigm about limited species turnover in the deep sea. Higher surface primary productivity was correlated with greater nematode densities, whereas diversity responses to the augmentation of surface productivity showed no trend. Areas subjected to a constant and low food input revealed similar nematode communities to other oligotrophic abyssal areas, while stations under high productivity were characterized by different dominant genera and Acantholaimus species, and by a generally low local diversity. Our results corroborate the species-energy hypothesis, where productivity can set a limit to the richness of an ecosystem. Finally, we observed no correlation between sediment variability and local diversity. Although differences in sediment variability were significant across stations, these had to be considered without effect on the nematode community structure in the studied abyssal areas.

Passive Plasma Contact Mechanisms for Small-Scale Spacecraft

NASA Astrophysics Data System (ADS)

McTernan, Jesse K.

Small-scale spacecraft represent a paradigm shift in how entities such as academia, industry, engineering firms, and the scientific community operate in space. However, although the paradigm shift produces unique opportunities to build satellites in unique ways for novel missions, there are also significant challenges that must be addressed. This research addresses two of the challenges associated with small-scale spacecraft: 1) the miniaturization of spacecraft and associated instrumentation and 2) the need to transport charge across the spacecraft-environment boundary. As spacecraft decrease in size, constraints on the size, weight, and power of on-board instrumentation increase--potentially limiting the instrument's functionality or ability to integrate with the spacecraft. These constraints drive research into mechanisms or techniques that use little or no power and efficiently utilize existing resources. One limited resource on small-scale spacecraft is outer surface area, which is often covered with solar panels to meet tight power budgets. This same surface area could also be needed for passive neutralization of spacecraft charging. This research explores the use of a transparent, conductive layer on the solar cell coverglass that is electrically connected to spacecraft ground potential. This dual-purpose material facilitates the use of outer surfaces for both energy harvesting of solar photons as well as passive ion collection. Mission capabilities such as in-situ plasma measurements that were previously infeasible on small-scale platforms become feasible with the use of indium tin oxide-coated solar panel coverglass. We developed test facilities that simulate the space environment in low Earth orbit to test the dual-purpose material and the various application of this approach. Particularly, this research is in support of two upcoming missions: OSIRIS-3U, by Penn State's Student Space Programs Lab, and MiTEE, by the University of Michigan. The purpose of OSIRIS-3U is to investigate the effects of space weather on the ionosphere. The spacecraft will use a pulsed Langmuir probe, an instrument now enabled on small-scale spacecraft through the techniques outlined in this research.

Multi-Scale Fractal Analysis of Image Texture and Pattern

NASA Technical Reports Server (NTRS)

Emerson, Charles W.

1998-01-01

Fractals embody important ideas of self-similarity, in which the spatial behavior or appearance of a system is largely independent of scale. Self-similarity is defined as a property of curves or surfaces where each part is indistinguishable from the whole, or where the form of the curve or surface is invariant with respect to scale. An ideal fractal (or monofractal) curve or surface has a constant dimension over all scales, although it may not be an integer value. This is in contrast to Euclidean or topological dimensions, where discrete one, two, and three dimensions describe curves, planes, and volumes. Theoretically, if the digital numbers of a remotely sensed image resemble an ideal fractal surface, then due to the self-similarity property, the fractal dimension of the image will not vary with scale and resolution. However, most geographical phenomena are not strictly self-similar at all scales, but they can often be modeled by a stochastic fractal in which the scaling and self-similarity properties of the fractal have inexact patterns that can be described by statistics. Stochastic fractal sets relax the monofractal self-similarity assumption and measure many scales and resolutions in order to represent the varying form of a phenomenon as a function of local variables across space. In image interpretation, pattern is defined as the overall spatial form of related features, and the repetition of certain forms is a characteristic pattern found in many cultural objects and some natural features. Texture is the visual impression of coarseness or smoothness caused by the variability or uniformity of image tone or color. A potential use of fractals concerns the analysis of image texture. In these situations it is commonly observed that the degree of roughness or inexactness in an image or surface is a function of scale and not of experimental technique. The fractal dimension of remote sensing data could yield quantitative insight on the spatial complexity and information content contained within these data. A software package known as the Image Characterization and Modeling System (ICAMS) was used to explore how fractal dimension is related to surface texture and pattern. The ICAMS software was verified using simulated images of ideal fractal surfaces with specified dimensions. The fractal dimension for areas of homogeneous land cover in the vicinity of Huntsville, Alabama was measured to investigate the relationship between texture and resolution for different land covers.

Estimation of Land Surface Temperature for the Quantitative Analysis of Land Cover of Lower Areas of Sindh to Assess the Impacts of Climate Variability

NASA Astrophysics Data System (ADS)

Qaisar, Maha

2016-07-01

Due to the present land use practices and climate variability, drastic shifts in regional climate and land covers are easily seen and their future reduction and gain are too well predicted. Therefore, there is an increasing need for data on land-cover changes at narrow and broad spatial scales. In this study, a remote sensing-based technique for land-cover-change analysis is applied to the lower Sindh areas for the last decade. Landsat satellite products were analyzed on an alternate yearly basis, from 1990 to 2016. Then Land-cover-change magnitudes were measured and mapped for alternate years. Land Surface Temperature (LST) is one of the critical elements in the natural phenomena of surface energy and water balance at local and global extent. However, LST was computed by using Landsat thermal bands via brightness temperature and a vegetation index. Normalized difference vegetation index (NDVI) was interpreted and maps were achieved. LST reflected NDVI patterns with complexity of vegetation patterns. Along with this, Object Based Image Analysis (OBIA) was done for classifying 5 major classes of water, vegetation, urban, marshy lands and barren lands with significant map layouts. Pakistan Meteorological Department provided the climate data in which rainfall, temperature and air temperature are included. Once the LST and OBIA are performed, overlay analysis was done to correlate the results of LST with OBIA and LST with meteorological data to ascertain the changes in land covers due to increasing centigrade of LST. However, satellite derived LST was also correlated with climate data for environmental analysis and to estimate Land Surface Temperature for assessing the inverse impacts of climate variability. This study's results demonstrate the land-cover changes in Lower Areas of Sindh including the Indus Delta mostly involve variations in land-cover conditions due to inter-annual climatic variability and temporary shifts in seasonality. However it is too concluded that transitory alteration of the biophysical characteristics of the surface driven by variations in rainfall is the prevailing progression. Moreover, future work will focus on finer-scale analysis and validations of patterns of changes due to rapid urbanization and population explosion in poverty stricken areas of Sindh which are posing an adverse impact on the land utilization and in turn increasing the land surface temperature and ultimately more stress on the low lying areas of Sindh i.e. Indus Delta will be losing its productivity and capacity to bear biodiversity whether the fauna or flora. Hence, this regional scale problem will become a global concern. Therefore, it is needed to stop the menace in its starting phase to mitigate the problem and to bring minds on this horrendous situation.

Integration of remote sensing based surface information into a three-dimensional microclimate model

NASA Astrophysics Data System (ADS)

Heldens, Wieke; Heiden, Uta; Esch, Thomas; Mueller, Andreas; Dech, Stefan

2017-03-01

Climate change urges cities to consider the urban climate as part of sustainable planning. Urban microclimate models can provide knowledge on the climate at building block level. However, very detailed information on the area of interest is required. Most microclimate studies therefore make use of assumptions and generalizations to describe the model area. Remote sensing data with area wide coverage provides a means to derive many parameters at the detailed spatial and thematic scale required by urban climate models. This study shows how microclimate simulations for a series of real world urban areas can be supported by using remote sensing data. In an automated process, surface materials, albedo, LAI/LAD and object height have been derived and integrated into the urban microclimate model ENVI-met. Multiple microclimate simulations have been carried out both with the dynamic remote sensing based input data as well as with manual and static input data to analyze the impact of the RS-based surface information and the suitability of the applied data and techniques. A valuable support of the integration of the remote sensing based input data for ENVI-met is the use of an automated processing chain. This saves tedious manual editing and allows for fast and area wide generation of simulation areas. The analysis of the different modes shows the importance of high quality height data, detailed surface material information and albedo.

Global direct pressures on biodiversity by large-scale metal mining: Spatial distribution and implications for conservation.

PubMed

Murguía, Diego I; Bringezu, Stefan; Schaldach, Rüdiger

2016-09-15

Biodiversity loss is widely recognized as a serious global environmental change process. While large-scale metal mining activities do not belong to the top drivers of such change, these operations exert or may intensify pressures on biodiversity by adversely changing habitats, directly and indirectly, at local and regional scales. So far, analyses of global spatial dynamics of mining and its burden on biodiversity focused on the overlap between mines and protected areas or areas of high value for conservation. However, it is less clear how operating metal mines are globally exerting pressure on zones of different biodiversity richness; a similar gap exists for unmined but known mineral deposits. By using vascular plants' diversity as a proxy to quantify overall biodiversity, this study provides a first examination of the global spatial distribution of mines and deposits for five key metals across different biodiversity zones. The results indicate that mines and deposits are not randomly distributed, but concentrated within intermediate and high diversity zones, especially bauxite and silver. In contrast, iron, gold, and copper mines and deposits are closer to a more proportional distribution while showing a high concentration in the intermediate biodiversity zone. Considering the five metals together, 63% and 61% of available mines and deposits, respectively, are located in intermediate diversity zones, comprising 52% of the global land terrestrial surface. 23% of mines and 20% of ore deposits are located in areas of high plant diversity, covering 17% of the land. 13% of mines and 19% of deposits are in areas of low plant diversity, comprising 31% of the land surface. Thus, there seems to be potential for opening new mines in areas of low biodiversity in the future. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bi-scale analysis of multitemporal land cover fractions for wetland vegetation mapping

NASA Astrophysics Data System (ADS)

Michishita, Ryo; Jiang, Zhiben; Gong, Peng; Xu, Bing

2012-08-01

Land cover fractions (LCFs) derived through spectral mixture analysis are useful in understanding sub-pixel information. However, few studies have been conducted on the analysis of time-series LCFs. Although multi-scale comparisons of spectral index, hard classification, and land surface temperature images have received attention, rarely have these approaches been applied to LCFs. This study compared the LCFs derived through Multiple Endmember Spectral Mixture Analysis (MESMA) using the time-series Landsat Thematic Mapper (TM) and Terra Moderate Resolution Imaging Spectroradiometer (MODIS) data acquired in the Poyang Lake area, China between 2004 and 2005. Specifically, we aimed to: (1) propose an approach for optimal endmember (EM) selection in time-series MESMA; (2) understand the trends in time-series LCFs derived from the TM and MODIS data; and (3) examine the trends in the correlation between the bi-scale LCFs derived from the time-series TM and MODIS data. Our results indicated: (1) the EM spectra chosen according to the proposed hierarchical three-step approach (overall, seasonal, and individual) accurately modeled the both the TM and MODIS images; (2) green vegetation (GV) and NPV/soil/impervious surface (N/S/I) classes followed sine curve trends in the overall area, while the two water classes displayed the water level change pattern in the areas primarily covered with wetland vegetation; and (3) GV, N/S/I, and bright water classes indicated a moderately high agreement between the TM and MODIS LCFs in the whole area (adjusted R2 ⩾ 0.6). However, low levels of correlations were found in the areas primarily dominated by wetland vegetation for all land cover classes.

Shape shifting predicts ontogenetic changes in metabolic scaling in diverse aquatic invertebrates

PubMed Central

Glazier, Douglas S.; Hirst, Andrew G.; Atkinson, David

2015-01-01

Metabolism fuels all biological activities, and thus understanding its variation is fundamentally important. Much of this variation is related to body size, which is commonly believed to follow a 3/4-power scaling law. However, during ontogeny, many kinds of animals and plants show marked shifts in metabolic scaling that deviate from 3/4-power scaling predicted by general models. Here, we show that in diverse aquatic invertebrates, ontogenetic shifts in the scaling of routine metabolic rate from near isometry (bR = scaling exponent approx. 1) to negative allometry (bR < 1), or the reverse, are associated with significant changes in body shape (indexed by bL = the scaling exponent of the relationship between body mass and body length). The observed inverse correlations between bR and bL are predicted by metabolic scaling theory that emphasizes resource/waste fluxes across external body surfaces, but contradict theory that emphasizes resource transport through internal networks. Geometric estimates of the scaling of surface area (SA) with body mass (bA) further show that ontogenetic shifts in bR and bA are positively correlated. These results support new metabolic scaling theory based on SA influences that may be applied to ontogenetic shifts in bR shown by many kinds of animals and plants. PMID:25652833

Application and comparison of the SCS-CN-based rainfall-runoff model in meso-scale watershed and field scale

NASA Astrophysics Data System (ADS)

Luo, L.; Wang, Z.

2010-12-01

Soil Conservation Service Curve Number (SCS-CN) based hydrologic model, has widely been used for agricultural watersheds in recent years. However, there will be relative error when applying it due to differentiation of geographical and climatological conditions. This paper introduces a more adaptable and propagable model based on the modified SCS-CN method, which specializes into two different scale cases of research regions. Combining the typical conditions of the Zhanghe irrigation district in southern part of China, such as hydrometeorologic conditions and surface conditions, SCS-CN based models were established. The Xinbu-Qiao River basin (area =1207 km2) and the Tuanlin runoff test area (area =2.87 km2)were taken as the study areas of basin scale and field scale in Zhanghe irrigation district. Applications were extended from ordinary meso-scale watershed to field scale in Zhanghe paddy field-dominated irrigated . Based on actual measurement data of land use, soil classification, hydrology and meteorology, quantitative evaluation and modifications for two coefficients, i.e. preceding loss and runoff curve, were proposed with corresponding models, table of CN values for different landuse and AMC(antecedent moisture condition) grading standard fitting for research cases were proposed. The simulation precision was increased by putting forward a 12h unit hydrograph of the field area, and 12h unit hydrograph were simplified. Comparison between different scales show that it’s more effectively to use SCS-CN model on field scale after parameters calibrated in basin scale These results can help discovering the rainfall-runoff rule in the district. Differences of established SCS-CN model's parameters between the two study regions are also considered. Varied forms of landuse and impacts of human activities were the important factors which can impact the rainfall-runoff relations in Zhanghe irrigation district.

Large-scale synthesis of high-quality hexagonal boron nitride nanosheets for large-area graphene electronics.

PubMed

Lee, Kang Hyuck; Shin, Hyeon-Jin; Lee, Jinyeong; Lee, In-yeal; Kim, Gil-Ho; Choi, Jae-Young; Kim, Sang-Woo

2012-02-08

Hexagonal boron nitride (h-BN) has received a great deal of attention as a substrate material for high-performance graphene electronics because it has an atomically smooth surface, lattice constant similar to that of graphene, large optical phonon modes, and a large electrical band gap. Herein, we report the large-scale synthesis of high-quality h-BN nanosheets in a chemical vapor deposition (CVD) process by controlling the surface morphologies of the copper (Cu) catalysts. It was found that morphology control of the Cu foil is much critical for the formation of the pure h-BN nanosheets as well as the improvement of their crystallinity. For the first time, we demonstrate the performance enhancement of CVD-based graphene devices with large-scale h-BN nanosheets. The mobility of the graphene device on the h-BN nanosheets was increased 3 times compared to that without the h-BN nanosheets. The on-off ratio of the drain current is 2 times higher than that of the graphene device without h-BN. This work suggests that high-quality h-BN nanosheets based on CVD are very promising for high-performance large-area graphene electronics. © 2012 American Chemical Society

Sunlight-thin nanophotonic monocrystalline silicon solar cells

NASA Astrophysics Data System (ADS)

Depauw, Valérie; Trompoukis, Christos; Massiot, Inès; Chen, Wanghua; Dmitriev, Alexandre; Cabarrocas, Pere Roca i.; Gordon, Ivan; Poortmans, Jef

2017-09-01

Introducing nanophotonics into photovoltaics sets the path for scaling down the surface texture of crystalline-silicon solar cells from the micro- to the nanoscale, allowing to further boost the photon absorption while reducing silicon material loss. However, keeping excellent electrical performance has proven to be very challenging, as the absorber is damaged by the nanotexturing and the sensitivity to the surface recombination is dramatically increased. Here we realize a light-wavelength-scale nanotextured monocrystalline silicon cell with the confirmed efficiency of 8.6% and an effective thickness of only 830 nm. For this we adopt a self-assembled large-area and industry-compatible amorphous ordered nanopatterning, combined with an advanced surface passivation, earning strongly enhanced solar light absorption while retaining efficient electron collection. This prompts the development of highly efficient flexible and semitransparent photovoltaics, based on the industrially mature monocrystalline silicon technology.

An integrated view of the 1987 Australian monsoon and its mesoscale convective systems. II - Vertical structure

NASA Technical Reports Server (NTRS)

Mapes, Brian; Houze, Robert A., Jr.

1993-01-01

The vertical structure of monsoon thermal forcing by precipitating convection is diagnosed in terms of horizontal divergence. Airborne Doppler-radar divergence profiles from nine diverse mesoscale convective systems (MCSs) are presented. The MCSs consisted of multicellular convective elements which in time gave rise to areas of stratiform precipitation. Each of the three basic building blocks of the MCSs - convective, intermediary, and stratiform precipitation areas - has a consistent, characteristic divergence profile. Convective areas have low-level convergence, with its peak at 2-4 km altitude, and divergence above 6 km. Intermediary areas have convergence aloft, peaked near 10 km, feeding into mean ascent high in the upper troposphere. Stratiform areas have mid-level convergence, indicating a mesoscale downdraught below the melting level, and a mesoscale updraught aloft. Rawinsonde composite divergence profiles agree with the Doppler data in at least one important respect: the lower-tropospheric convergence into the MCSs peaks 2-4-km above the surface. Rawinsonde vorticity profiles show that monsoonal tropical cyclones spin-up at these elevated levels first, then later descend to the surface. Rawinsonde observations on a larger, continental scale demonstrate that at large horizontal scales only the 'gravest vertical mode' of MCS heating is felt, while the effects of shallower components of the heating (or divergence) profiles are trapped near the heating, as predicted by geostrophic adjustment theory.

The Use of the Airborne Thermal/Visible Land Application Sensor (ATLAS) to Determine the Thermal Response Numbers for Urban Areas

NASA Technical Reports Server (NTRS)

Luvall, Jeffrey C.; Rickman, Doug; Quattroch, Dale; Estes. Maury

2007-01-01

Although satellite data are very useful for analysis of the urban heat island effect at a coarse scale, they do not lend themselves to developing a better understanding of which surfaces across the city contribute or drive the development of the urban heat island effect. Analysis of thermal energy responses for specific or discrete surfaces typical of the urban landscape (e.g., asphalt, building rooftops, vegetation) requires measurements at a very fine spatial scale (i.e., < 15m) to adequately resolve these surfaces and their attendant thermal energy regimes. Additionally, very fine scale spatial resolution thermal infrared data, such as that obtained from aircraft, are very useful for demonstrating to planning officials, policy makers, and the general populace the benefits of the urban forest. These benefits include mitigating the urban heat island effect, making cities more aesthetically pleasing and more habitable environments, and aid in overall cooling of the community. High spatial resolution thermal data are required to quantify how artificial surfaces within the city contribute to an increase in urban heating and the benefit of cool surfaces (e.g., surface coatings that reflect much of the incoming solar radiation as opposed to absorbing it thereby lowering urban temperatures). The TRN (thermal response number)(Luvall and Holbo 1989) is a technique using aircraft remotely sensed surface temperatures to quantify the thermal response of urban surfaces. The TRN was used to quantify the thermal response of various urban surface types ranging from completely vegetated surfaces to asphalt and concrete parking lots for several cities in the United States.

Effect of micro-scale texturing on the cutting tool performance

NASA Astrophysics Data System (ADS)

Vasumathy, D.; Meena, Anil

2018-05-01

The present study is mainly focused on the cutting performance of the micro-scale textured carbide tools while turning AISI 304 austenitic stainless steel under dry cutting environment. The texture on the rake face of the carbide tools was fabricated by laser machining. The cutting performance of the textured tools was further compared with conventional tools in terms of cutting forces, tool wear, machined surface quality and chip curl radius. SEM and EDS analyses have been also performed to better understand the tool surface characteristics. Results show that the grooves help in breaking the tool-chip contact leading to a lesser tool-chip contact area which results in reduced iron (Fe) adhesion to the tool.

Shortwave surface radiation network for observing small-scale cloud inhomogeneity fields

NASA Astrophysics Data System (ADS)

Lakshmi Madhavan, Bomidi; Kalisch, John; Macke, Andreas

2016-03-01

As part of the High Definition Clouds and Precipitation for advancing Climate Prediction Observational Prototype Experiment (HOPE), a high-density network of 99 silicon photodiode pyranometers was set up around Jülich (10 km × 12 km area) from April to July 2013 to capture the small-scale variability of cloud-induced radiation fields at the surface. In this paper, we provide the details of this unique setup of the pyranometer network, data processing, quality control, and uncertainty assessment under variable conditions. Some exemplary days with clear, broken cloudy, and overcast skies were explored to assess the spatiotemporal observations from the network along with other collocated radiation and sky imager measurements available during the HOPE period.

Models of the diffuse radar backscatter from Mars

NASA Technical Reports Server (NTRS)

England, A. W.; Austin, R. T.

1991-01-01

The topographies of several debris flow units near the Mount St. Helens Volcano were measured at lateral scales of millimeters to meters in September 1990. The objective was to measure the surface roughness of the debris flows at scales smaller than, on the order of, and larger that the radar wavelength of common remote sensing radars. A laser profiling system and surveying instruments were used to obtain elevation data for square areas that varied in size from 10 to 32 cm. The elevation data were converted to estimates of the power spectrum of surface roughness. The conversions were based upon standard periodogram techniques, and upon a modified spectral estimation technique that was developed.

Small scale wind tunnel model investigation of hybrid high lift systems combining upper surface blowing with the internally blown flap

NASA Technical Reports Server (NTRS)

Waites, W. L.; Chin, Y. T.

1974-01-01

A small-scale wind tunnel test of a two engine hybrid model with upper surface blowing on a simulated expandable duct internally blown flap was accomplished in a two phase program. The low wing Phase I model utilized 0.126c radius Jacobs/Hurkamp flaps and 0.337c radius Coanda flaps. The high wing Phase II model was utilized for continued studies on the Jacobs/Hurkamp flap. Principal study areas included: basic data both engines operative and with an engine out, control flap utilization, horizontal tail effectiveness, spoiler effectiveness, USB nacelle deflector study and USB/IBF pressure ratio effects.

Direct evidence for organic carbon preservation as clay-organic nanocomposites in a Devonian black shale; from deposition to diagenesis

NASA Astrophysics Data System (ADS)

Kennedy, Martin John; Löhr, Stefan Carlos; Fraser, Samuel Alex; Baruch, Elizabeth Teresa

2014-02-01

The burial of marine sourced organic carbon (OC) in continental margin sediments is most commonly linked to oceanographic regulation of bottom-water oxygenation (anoxia) and/or biological productivity. Here we show an additional influence in the Devonian Woodford Shale, in which OC occurs as nanometer intercalations with specific phyllosilicate minerals (mixed-layer illite/smectite) that we term organo-mineral nanocomposites. High resolution transmission electron microscopic (HRTEM) images provide direct evidence of this nano-scale relationship. While discrete micron-scale organic particles, such as Tasmanites algal cysts, are present in some lamina, a strong relation between total organic carbon (TOC) and mineral surface area (MSA) over a range of 15% TOC indicate that the dominant association of organic carbon is with mineral surfaces and not as discrete pelagic grains, consistent with HRTEM images of nanocomposites. Where periods of oxygenation are indicated by bioturbation, this relationship is modified by a shift to lower OC loading on mineral surfaces and reduced MSA variability likely resulting from biological mixing and homogenization of the sediment, oxidative burn down of OC and/or stripping of OC from minerals in animal guts. The TOC-MSA relationship extends across a range of burial depths and thermal maturities into the oil window and persists through partial illitization. Where illitization occurs, the loss of mineral surface area associated with the collapse of smectite interlayer space results in a systematic increase in TOC:MSA and reorganization of organic carbon and clays into nano-scale aggregates. While the Woodford Shale is representative of black shale deposits commonly thought to record heightened marine productivity and/or anoxia, our results point to the importance of high surface area clay minerals for OC enrichment. Given that the vast majority of these clay minerals are formed in soils before being transported to continental margin settings, their mineralogy and attendant preservative potential is primarily a function of continental climate and provenance making these deposits a sensitive recorder of land as well as oceanographic change.

Sulfates on Mars: TES Observations and Thermal Inertia Data

NASA Astrophysics Data System (ADS)

Cooper, C. D.; Mustard, J. F.

2001-05-01

The high resolution thermal emission spectra returned by the TES spectrometer on the MGS spacecraft have allowed the mapping of a variety of minerals and rock types by different sets of researchers. Recently, we have used a linear deconvolution approach to compare sulfate-palagonite soil mixtures created in the laboratory with Martian surface spectra. This approach showed that a number of areas on Mars have spectral properties that match those of sulfate-cemented soils (but neither loose powder mixtures of sulfates and soils nor sand-sized grains of disaggregated crusted soils). These features do not appear to be caused by atmospheric or instrumental effects and are thus believed to be related to surface composition and texture. The distribution and physical state of sulfate are important pieces of information for interpreting surface processes on Mars. A number of different mechanisms could have deposited sulfate in surface layers. Some of these include evaporation of standing bodies of water, aerosol deposition of volcanic gases, hydrothermal alteration from groundwater, and in situ interaction between the atmosphere and soil. The areas on Mars with cemented sulfate signatures are spread across a wide range of elevations and are generally large in spatial scale. Some of the areas are associated with volcanic regions, but many are in dark red plains that have previously been interpreted as duricrust deposits. Our current work compares the distribution of sulfate-cemented soils as mapped by the spectral deconvolution approach with thermal inertia maps produced from both Viking and MGS-TES. Duricrust regions, interpreted from intermediate thermal inertia values, are large regions thought to be sulfate-cemented soils similar to coherent, sulfate-rich materials seen at the Viking lander sites. Our observations of apparent regions of cemented sulfate are also large in spatial extent. This scale information is important for evaluating formation mechanisms for the sulfate material, although we currently lack the data to analyze sulfates on the outcrop scale. Analyzing our sulfate maps from spectral deconvolution together with thermal inertia data gives more information on the distribution of possible duricrusts, which provides insight into possible surface processes on Mars.

Simulating pesticide transport in urbanized catchments: a new spatially-distributed dynamic pesticide runoff model

NASA Astrophysics Data System (ADS)

Tang, Ting; Seuntjens, Piet; van Griensven, Ann; Bronders, Jan

2016-04-01

Urban areas can significantly contribute to pesticide contamination in surface water. However, pesticide behaviours in urban areas, particularly on hard surfaces, are far less studied than those in agricultural areas. Pesticide application on hard surfaces (e.g. roadsides and walkways) is of particular concern due to the high imperviousness and therefore high pesticide runoff potential. Experimental studies have shown that pesticide behaviours on and interactions with hard surfaces are important factors controlling the pesticide runoff potential, and therefore the magnitude and timing of peak concentrations in surface water. We conceptualized pesticide behaviours on hard surfaces and incorporated the conceptualization into a new pesticide runoff model. The pesticide runoff model was implemented in a catchment hydrological model WetSpa-Python (Water and Energy Transfer between Soil, Plants and Atmosphere, Python version). The conceptualization for pesticide processes on hard surfaces accounts for the differences in pesticide behaviour on different hard surfaces. Four parameters are used to describe the partitioning and wash-off of each pesticide on hard surfaces. We tested the conceptualization using experimental dataset for five pesticides on two types of hard surfaces, namely concrete and asphalt. The conceptualization gave good performance in accounting for the wash-off pattern for the modelled pesticides and surfaces, according to quantitative evaluations using the Nash-Sutcliffe efficiency and percent bias. The resulting pesticide runoff model WetSpa-PST (WetSpa for PeSTicides) can simulate pesticides and their metabolites at the catchment scale. Overall, it includes four groups of pesticide processes, namely pesticide application, pesticide interception by plant foliage, pesticide processes on land surfaces (including partitioning, degradation and wash-off on hard surface; partitioning, dissipation, infiltration and runoff in soil) and pesticide processes in depression storage (including degradation, infiltration and runoff). Processes on hard surfaces employs the conceptualization described in the paragraph above. The WetSpa-PST model can account for various spatial details of the urban features in a catchment, such as asphalt, concrete and roof areas. The distributed feature also allows users to input detailed pesticide application data of both non-point and point origins. Thanks to the Python modelling framework prototype used in the WetSpa-Python model, processes in the WetSpa-PST model can be simulated at different time steps depending on data availability and the characteristic temporal scale of each process. This helps to increase the computational accuracy during heavy rainfall events, especially for the associated fast transport of pesticides into surface water. Overall, the WetSpa-PST model has good potential in predicting effects of management options on pesticide releases from heavily urbanized catchments.

Large-scale structural alteration of brain in epileptic children with SCN1A mutation.

PubMed

Lee, Yun-Jeong; Yum, Mi-Sun; Kim, Min-Jee; Shim, Woo-Hyun; Yoon, Hee Mang; Yoo, Il Han; Lee, Jiwon; Lim, Byung Chan; Kim, Ki Joong; Ko, Tae-Sung

2017-01-01

Mutations in SCN1A gene encoding the alpha 1 subunit of the voltage gated sodium channel are associated with several epilepsy syndromes including genetic epilepsy with febrile seizures plus (GEFS +) and severe myoclonic epilepsy of infancy (SMEI). However, in most patients with SCN1A mutation, brain imaging has reported normal or non-specific findings including cerebral or cerebellar atrophy. The aim of this study was to investigate differences in brain morphometry in epileptic children with SCN1A mutation compared to healthy control subjects. We obtained cortical morphology (thickness, and surface area) and brain volume (global, subcortical, and regional) measurements using FreeSurfer (version 5.3.0, https://surfer.nmr.mgh.harvard.edu) and compared measurements of children with epilepsy and SCN1A gene mutation ( n  = 21) with those of age and gender matched healthy controls ( n  = 42). Compared to the healthy control group, children with epilepsy and SCN1A gene mutation exhibited smaller total brain, total gray matter and white matter, cerebellar white matter, and subcortical volumes, as well as mean surface area and mean cortical thickness. A regional analysis revealed significantly reduced gray matter volume in the patient group in the bilateral inferior parietal, left lateral orbitofrontal, left precentral, right postcentral, right isthmus cingulate, right middle temporal area with smaller surface area and white matter volume in some of these areas. However, the regional cortical thickness was not significantly different in two groups. This study showed large-scale developmental brain changes in patients with epilepsy and SCN1A gene mutation, which may be associated with the core symptoms of the patients. Further longitudinal MRI studies with larger cohorts are required to confirm the effect of SCN1A gene mutation on structural brain development.

Impacts of large scale afforestation on regional climate: a case study in the Kubuqi Desert, Inner Mongolia based on WRF model

NASA Astrophysics Data System (ADS)

Wang, L.; Lin, G.; Feng, D.; Chen, S.; Schultz, N. M.; Fu, C.; Wei, Z.; Yin, C.; Wang, W.; Lee, X.

2017-12-01

To better design climate mitigation strategies, it is important to understand the response of regional climatic indicators and related biophysical forcings to large scale afforestation projects. The response of surface temperature (Ts) caused by afforestation activities in the Kubuqi Desert, Inner Mongolia, China is simulated by the weather research and forecasting (WRF) model and the temperature changes (ΔTs) are decomposed into contributions from changes in surface albedo, surface roughness, Bowen ratio and ground heat flux using the intrinsic biophysical mechanism (IBPM). The 30-m resolution land cover maps of the Kubuqi Desert corresponding to 2000 and 2010 conditions are analyzed and the major land use changes are found to be an increase in the area of grassland (6%) and shrubland (15%), but a decrease in the area of bare land (21%) owed to the aerial seeding afforestation activities organized by Elion Resources Group, Co. and local government agencies. Our WRF simulations show that during winter, the increased cover of vegetation mainly has a warming effect (0.38 K) in the daytime due to the changes in albedo (0.24 K) and Bowen ratio (0.15 K). In the nighttime, the vegetation has a slight warming effect (0.2 K) mainly caused by energy redistribution associated with roughness change (0.2 K) as a result of vegetation turbulence, which brought heat from aloft to the surface. Although both roughness change (-0.35 K) and Bowen ratio change (-0.35 K) have cooling effects during summer days, the warming effect caused by radiative forcing (0.93 K) dominates the ΔTs. During summer nights, the change in surface temperature is not significant. Our findings demonstrate that the large-scale afforestation project in the Kubuqi Desert during a decade alters the regional surface temperature and the analysis of biophysical forcings changes using WRF simulation provides useful information for developing climate change mitigation strategies in semi-arid and arid regions.

Metropolitan Spokane Region Water Resources Study. Appendix B. Geology and Groundwater

DTIC Science & Technology

1976-01-01

to develop and confirm map data. Engineering Geology. Large-scale (1:24,000) mapping of near- surface soil classification and drainage characteristics...of the great lava field. By the beginning of the Pleistocene Ice Age, a broad valley had developed at about 1600 feet altitude. This pre-glacial...has developed on re level basalt surfaces. In the southern and eastern portions of the study area, chemical alteration has caused deep decomposition

Removal of dissolved and colloidal silica

DOEpatents

Midkiff, William S.

2002-01-01

Small amorphous silica particles are used to provide a relatively large surface area upon which silica will preferentially adsorb, thereby preventing or substantially reducing scaling caused by deposition of silica on evaporative cooling tower components, especially heat exchange surfaces. The silica spheres are contacted by the cooling tower water in a sidestream reactor, then separated using gravity separation, microfiltration, vacuum filtration, or other suitable separation technology. Cooling tower modifications for implementing the invention process have been designed.

Multi-scale evaporator architectures for geothermal binary power plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sabau, Adrian S; Nejad, Ali; Klett, James William

2016-01-01

In this paper, novel geometries of heat exchanger architectures are proposed for evaporators that are used in Organic Rankine Cycles. A multi-scale heat exchanger concept was developed by employing successive plenums at several length-scale levels. Flow passages contain features at both macro-scale and micro-scale, which are designed from Constructal Theory principles. Aside from pumping power and overall thermal resistance, several factors were considered in order to fully assess the performance of the new heat exchangers, such as weight of metal structures, surface area per unit volume, and total footprint. Component simulations based on laminar flow correlations for supercritical R134a weremore » used to obtain performance indicators.« less

SCIL nanoimprint solutions: high-volume soft NIL for wafer scale sub-10nm resolution

NASA Astrophysics Data System (ADS)

Voorkamp, R.; Verschuuren, M. A.; van Brakel, R.

2016-10-01

Nano-patterning materials and surfaces can add unique functionalities and properties which cannot be obtained in bulk or micro-structured materials. Examples range from hetro-epitaxy of semiconductor nano-wires to guiding cell expression and growth on medical implants. [1] Due to the cost and throughput requirements conventional nano-patterning techniques such as deep UV lithography (cost and flat substrate demands) and electron-beam lithography (cost, throughput) are not an option. Self-assembly techniques are being considered for IC manufacturing, but require nano-sized guiding patterns, which have to be fabricated in any case.[2] Additionally, the self-assembly process is highly sensitive to the environment and layer thickness, which is difficult to control on non-flat surfaces such as PV silicon wafers or III/V substrates. Laser interference lithography can achieve wafer scale periodic patterns, but is limited by the throughput due to intensity of the laser at the pinhole and only regular patterns are possible where the pattern fill fraction cannot be chosen freely due to the interference condition.[3] Nanoimprint lithography (NIL) is a promising technology for the cost effective fabrication of sub-micron and nano-patterns on large areas. The challenges for NIL are related to the technique being a contact method where a stamp which holds the patterns is required to be brought into intimate contact with the surface of the product. In NIL a strong distinction is made between the type of stamp used, either rigid or soft. Rigid stamps are made from patterned silicon, silica or plastic foils and are capable of sub-10nm resolution and wafer scale patterning. All these materials behave similar at the micro- to nm scale and require high pressures (5 - 50 Bar) to enable conformal contact to be made on wafer scales. Real world conditions such as substrate bow and particle contaminants complicate the use of rigid stamps for wafer scale areas, reducing stamp lifetime and yield. Soft stamps, usually based on silicone rubber, behave fundamentally different compared to rigid stamps on the macro-, micro- and nanometer level. The main limitation of traditional silicones is that they are too soft to support sub-micron features against surface tension based stamp deformation and collapse [4] and handling a soft stamp to achieve accurate feature placement on wafer scales to allow overlay alignment with sub-100nm overlay accuracy.

Colloid interaction energies for physically and chemically heterogeneous porous media

USDA-ARS?s Scientific Manuscript database

The mean and variance of the colloid interaction energy (phi*) as a function of separation distance (h) were calculated on physically and/or chemically heterogeneous solid surfaces at the representative elementary area (REA) scale. Nanoscale roughness was demonstrated to have a significant influence...

Multiple Scale Remote Sensing for Monitoring Rangelands

USDA-ARS?s Scientific Manuscript database

Based on a land-cover classification from NASA’s MODerate resolution Imaging Spectroradiometer (MODIS), rangelands cover 48% of the Earth’s land surface, not including Antarctica. Nearly all analyses imply the most economical means of monitoring large areas of rangelands worldwide is with remote se...

Fast ion transport at a gas-metal interface

DOE PAGES

McDevitt, Christopher J.; Tang, Xian-Zhu; Guo, Zehua

2017-11-06

Fast ion transport and the resulting fusion yield reduction are computed at a gas-metal interface. The extent of fusion yield reduction is observed to depend sensitively on the charge state of the surrounding pusher material and the width of the atomically mixed region. These sensitivities suggest that idealized boundary conditions often implemented at the gas-pusher interface for the purpose of estimating fast ion loss will likely overestimate fusion reactivity reduction in several important limits. Additionally, the impact of a spatially complex material interface is investigated by considering a collection of droplets of the pusher material immersed in a DT plasma.more » It is found that for small Knudsen numbers, the extent of fusion yield reduction scales with the surface area of the material interface. As the Knudsen number is increased, but, the simple surface area scaling is broken, suggesting that hydrodynamic mix has a nontrivial impact on the extent of fast ion losses.« less

Porous 3D graphene-based bulk materials with exceptional high surface area and excellent conductivity for supercapacitors

PubMed Central

Zhang, Long; Zhang, Fan; Yang, Xi; Long, Guankui; Wu, Yingpeng; Zhang, Tengfei; Leng, Kai; Huang, Yi; Ma, Yanfeng; Yu, Ao; Chen, Yongsheng

2013-01-01

Until now, few sp2 carbon materials simultaneously exhibit superior performance for specific surface area (SSA) and electrical conductivity at bulk state. Thus, it is extremely important to make such materials at bulk scale with those two outstanding properties combined together. Here, we present a simple and green but very efficient approach using two standard and simple industry steps to make such three-dimensional graphene-based porous materials at the bulk scale, with ultrahigh SSA (3523 m2/g) and excellent bulk conductivity. We conclude that these materials consist of mainly defected/wrinkled single layer graphene sheets in the dimensional size of a few nanometers, with at least some covalent bond between each other. The outstanding properties of these materials are demonstrated by their superior supercapacitor performance in ionic liquid with specific capacitance and energy density of 231 F/g and 98 Wh/kg, respectively, so far the best reported capacitance performance for all bulk carbon materials. PMID:23474952

Simulation of gas flow in micro-porous media with the regularized lattice Boltzmann method

DOE PAGES

Wang, Junjian; Kang, Qinjun; Wang, Yuzhu; ...

2017-06-01

One primary challenge for prediction of gas flow in the unconventional gas reservoir at the pore-scale such as shale and tight gas reservoirs is the geometric complexity of the micro-porous media. In this paper, a regularized multiple-relaxation-time (MRT) lattice Boltzmann (LB) model is applied to analyze gas flow in 2-dimensional micro-porous medium reconstructed by quartet structure generation set (QSGS) on pore-scale. In this paper, the velocity distribution inside the porous structure is presented and analyzed, and the effects of the porosity and specific surface area on the rarefied gas flow and apparent permeability are examined and investigated. The simulation resultsmore » indicate that the gas exhibits different flow behaviours at various pressure conditions and the gas permeability is strongly related to the pressure. Finally, the increased porosity or the decreased specific surface area leads to the increase of the gas apparent permeability, and the gas flow is more sensitive to the pore morphological properties at low-pressure conditions.« less

Simulation of gas flow in micro-porous media with the regularized lattice Boltzmann method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Junjian; Kang, Qinjun; Wang, Yuzhu

One primary challenge for prediction of gas flow in the unconventional gas reservoir at the pore-scale such as shale and tight gas reservoirs is the geometric complexity of the micro-porous media. In this paper, a regularized multiple-relaxation-time (MRT) lattice Boltzmann (LB) model is applied to analyze gas flow in 2-dimensional micro-porous medium reconstructed by quartet structure generation set (QSGS) on pore-scale. In this paper, the velocity distribution inside the porous structure is presented and analyzed, and the effects of the porosity and specific surface area on the rarefied gas flow and apparent permeability are examined and investigated. The simulation resultsmore » indicate that the gas exhibits different flow behaviours at various pressure conditions and the gas permeability is strongly related to the pressure. Finally, the increased porosity or the decreased specific surface area leads to the increase of the gas apparent permeability, and the gas flow is more sensitive to the pore morphological properties at low-pressure conditions.« less

Mining influence on underground water resources in arid and semiarid regions

NASA Astrophysics Data System (ADS)

Luo, A. K.; Hou, Y.; Hu, X. Y.

2018-02-01

Coordinated mining of coal and water resources in arid and semiarid regions has traditionally become a focus issue. The research takes Energy and Chemical Base in Northern Shaanxi as an example, and conducts statistical analysis on coal yield and drainage volume from several large-scale mines in the mining area. Meanwhile, research determines average water volume per ton coal, and calculates four typical years’ drainage volume in different mining intensity. Then during mining drainage, with the combination of precipitation observation data in recent two decades and water level data from observation well, the calculation of groundwater table, precipitation infiltration recharge, and evaporation capacity are performed. Moreover, the research analyzes the transforming relationship between surface water, mine water, and groundwater. The result shows that the main reason for reduction of water resources quantity and transforming relationship between surface water, groundwater, and mine water is massive mine drainage, which is caused by large-scale coal mining in the research area.

Comparison of the impact of scaler material composition on polished titanium implant abutment surfaces.

PubMed

Hasturk, Hatice; Nguyen, Daniel Huy; Sherzai, Homa; Song, Xiaoping; Soukos, Nikos; Bidlack, Felicitas B; Van Dyke, Thomas E

2013-08-01

The purpose of this study was to compare the impact of the removal of biofilm with hand scalers of different material composition on the surface of implant abutments by assessing the surface topography and residual plaque after scaling using scanning electron microscopy (SEM). Titanium implant analogs from 3 manufacturers (Straumann USA LLC, Andover, Maine, Nobel BioCare USA LLC, Yorba Linda, Cali, Astra Tech Implant Systems, Dentsply, Mölndal, Sweden) were mounted in stone in plastic vials individually with authentic prosthetic abutments. Plaque samples were collected from a healthy volunteer, inoculated into growth medium and incubated with the abutments anaerobically for 1 week. A blinded, calibrated hygienist performed scaling to remove the biofilm using 6 implant scalers (in triplicate), 1 scaler for 1 abutment. The abutments were mounted on an imaging stand and processed for SEM. Images were captured in 3 randomly designated areas of interest on each abutment. Analysis of the implant polished abutment surface and plaque area measurements were performed using ImageJ image analysis software. Surface alterations were characterized by the number, length, depth and the width of the scratches observed. Glass filled resin scalers resulted in significantly more and longer scratches on all 3 abutment types compared to other scalers, while unfilled resin scalers resulted in the least surface change (p < 0.05). Filled resin-graphite reinforced scalers, carbon fiber reinforced resin scalers and titanium scalers resulted in more superficial scratches compared to glass filled resin, as well as more scratches than unfilled resin. No statistically significant differences were found between scalers and abutments with regard to plaque removal. The impact of scalers on implant abutment surfaces varies between abutment types presumably due to different surface characteristics with no apparent advantage of one abutment type over the other with regard to resistance to surface damage. Unfilled resin was found consistently to be the least damaging to abutment surfaces, although all scalers of all compositions caused detectable surface changes to polished surfaces of implant abutments.

A CSF-SPH method for simulating drainage and imbibition at pore-scale resolution while tracking interfacial areas

NASA Astrophysics Data System (ADS)

Sivanesapillai, Rakulan; Falkner, Nadine; Hartmaier, Alexander; Steeb, Holger

2016-09-01

We present a conservative smoothed particle hydrodynamics (SPH) model to study the flow of multiple, immiscible fluid phases in porous media using direct pore-scale simulations. Particular focus is put on continuously tracking the evolution of interfacial areas, which are considered to be important morphological quantities affecting multiphase transport in porous media. In addition to solving the Navier-Stokes equations, the model accounts for the effects of capillarity at interfaces and contact lines. This is done by means of incorporating the governing interfacial mass and momentum balances using the continuum surface force (CSF) method, thus rendering model calibration routines unnecessary and minimizing the set of constitutive and kinematic assumptions. We address the application of boundary conditions at rigid solid surfaces and study the predictive capability of the model as well as optimal choices for numerical parameters using an extensive model validation procedure. We demonstrate the applicability of the model to simulate multiphase flows involving partial wettability, dynamic effects, large density ratios (up to 1000), large viscosity ratios (up to 100), as well as fragmentation and coalescence of fluid phases. The model is used to study the evolution of fluid-fluid interfacial areas during saturation-controlled primary drainage and main imbibition of heterogeneous pore spaces at low capillary numbers. A variety of pore-scale effects, such as wetting phase entrapment and fragmentation due to snap-off, are observed. Specific fluid-fluid interfacial area is observed to monotonically increase during primary drainage and hysteretic effects are apparent during main imbibition.

Quantitative framework for preferential flow initiation and partitioning

USGS Publications Warehouse

Nimmo, John R.

2016-01-01

A model for preferential flow in macropores is based on the short-range spatial distribution of soil matrix infiltrability. It uses elementary areas at two different scales. One is the traditional representative elementary area (REA), which includes a sufficient heterogeneity to typify larger areas, as for measuring field-scale infiltrability. The other, called an elementary matrix area (EMA), is smaller, but large enough to represent the local infiltrability of soil matrix material, between macropores. When water is applied to the land surface, each EMA absorbs water up to the rate of its matrix infiltrability. Excess water flows into a macropore, becoming preferential flow. The land surface then can be represented by a mesoscale (EMA-scale) distribution of matrix infiltrabilities. Total preferential flow at a given depth is the sum of contributions from all EMAs. Applying the model, one case study with multi-year field measurements of both preferential and diffuse fluxes at a specific depth was used to obtain parameter values by inverse calculation. The results quantify the preferential–diffuse partition of flow from individual storms that differed in rainfall amount, intensity, antecedent soil water, and other factors. Another case study provided measured values of matrix infiltrability to estimate parameter values for comparison and illustrative predictions. These examples give a self-consistent picture from the combination of parameter values, directions of sensitivities, and magnitudes of differences caused by different variables. One major practical use of this model is to calculate the dependence of preferential flow on climate-related factors, such as varying soil wetness and rainfall intensity.

On the Size Dependence of Molar and Specific Properties of Independent Nano-phases and Those in Contact with Other Phases

NASA Astrophysics Data System (ADS)

Kaptay, George

2018-05-01

Nano-materials are materials with at least one nano-phase. A nano-phase is a phase with at least one of its dimensions below 100 nm. It is shown here that nano-phases have at least 1% of their atoms along their surface layer. The ratio of surface atoms is proportional to the specific surface area of the phase, defined as the ratio of its surface area to its volume. Each specific/molar property has its bulk value and its surface value for the given phase, being always different, as the energetic states of the atoms in the bulk and in the surface layer of a phase are different. The average specific/molar property of a nano-phase is modeled here as a linear combination of the bulk and surface values of the same property, scaled with the ratio of the surface atoms. That makes the performance of all nano-phases proportional to their specific surface area. As the characteristic size of the nano-phase is inversely proportional to its specific surface area, all specific/molar properties of nano-phases are inversely proportional to the characteristic size of the phase. This is applied to the size dependence of the molar Gibbs energy of the nano-phase, which appears to be in agreement with the thermodynamics of Gibbs. This agreement proves the general validity of the present model on the size dependence of the specific/molar properties of independent nano-phases. It is shown that the properties of nano-phases are different for independent nano-phases (surrounded only by their equilibrium vapor phase) and for nano-phases in multi-phase situations, such as a liquid nano-droplet in the sessile drop configuration.

Fabrication of a 3D micro/nano dual-scale carbon array and its demonstration as the microelectrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Jiang, Shulan; Shi, Tielin; Gao, Yang; Long, Hu; Xi, Shuang; Tang, Zirong

2014-04-01

An easily accessible method is proposed for the fabrication of a 3D micro/nano dual-scale carbon array with a large surface area. The process mainly consists of three critical steps. Firstly, a hemispherical photoresist micro-array was obtained by the cost-effective nanoimprint lithography process. Then the micro-array was transformed into hierarchical structures with longitudinal nanowires on the microstructure surface by oxygen plasma etching. Finally, the micro/nano dual-scale carbon array was fabricated by carbonizing these hierarchical photoresist structures. It has also been demonstrated that the micro/nano dual-scale carbon array can be used as the microelectrodes for supercapacitors by the electrodeposition of a manganese dioxide (MnO2) film onto the hierarchical carbon structures with greatly enhanced electrochemical performance. The specific gravimetric capacitance of the deposited micro/nano dual-scale microelectrodes is estimated to be 337 F g-1 at the scan rate of 5 mV s-1. This proposed approach of fabricating a micro/nano dual-scale carbon array provides a facile way in large-scale microstructures’ manufacturing for a wide variety of applications, including sensors and on-chip energy storage devices.

High-Resolution Fibre-Optic Temperature Sensing: A New Tool to Study the Two-Dimensional Structure of Atmospheric Surface-Layer Flow

NASA Astrophysics Data System (ADS)

Thomas, Christoph K.; Kennedy, Adam M.; Selker, John S.; Moretti, Ayla; Schroth, Martin H.; Smoot, Alexander R.; Tufillaro, Nicholas B.; Zeeman, Matthias J.

2012-02-01

We present a novel approach based on fibre-optic distributed temperature sensing (DTS) to measure the two-dimensional thermal structure of the surface layer at high resolution (0.25 m, ≈0.5 Hz). Air temperature observations obtained from a vertically-oriented fibre-optics array of approximate dimensions 8 m × 8 m and sonic anemometer data from two levels were collected over a short grass field located in the flat bottom of a wide valley with moderate surface heterogeneity. The objectives of the study were to evaluate the potential of the DTS technique to study small-scale processes in the surface layer over a wide range of atmospheric stability, and to analyze the space-time dynamics of transient cold-air pools in the calm boundary layer. The time response and precision of the fibre-based temperatures were adequate to resolve individual sub-metre sized turbulent and non-turbulent structures, of time scales of seconds, in the convective, neutral, and stable surface layer. Meaningful sensible heat fluxes were computed using the eddy-covariance technique when combined with vertical wind observations. We present a framework that determines the optimal environmental conditions for applying the fibre-optics technique in the surface layer and identifies areas for potentially significant improvements of the DTS performance. The top of the transient cold-air pool was highly non-stationary indicating a superposition of perturbations of different time and length scales. Vertical eddy scales in the strongly stratified transient cold-air pool derived from the DTS data agreed well with the buoyancy length scale computed using the vertical velocity variance and the Brunt-Vaisala frequency, while scales for weak stratification disagreed. The high-resolution DTS technique opens a new window into spatially sampling geophysical fluid flows including turbulent energy exchange.

Quantitative study of Xanthosoma violaceum leaf surfaces using RIMAPS and variogram techniques.

PubMed

Favret, Eduardo A; Fuentes, Néstor O; Molina, Ana M

2006-08-01

Two new imaging techniques (rotated image with maximum averaged power spectrum (RIMAPS) and variogram) are presented for the study and description of leaf surfaces. Xanthosoma violaceum was analyzed to illustrate the characteristics of both techniques. Both techniques produce a quantitative description of leaf surface topography. RIMAPS combines digitized images rotation with Fourier transform, and it is used to detect patterns orientation and characteristics of surface topography. Variogram relates the mathematical variance of a surface with the area of the sample window observed. It gives the typical scale lengths of the surface patterns. RIMAPS detects the morphological variations of the surface topography pattern between fresh and dried (herbarium) samples of the leaf. The variogram method finds the characteristic dimensions of the leaf microstructure, i.e., cell length, papillae diameter, etc., showing that there are not significant differences between dry and fresh samples. The results obtained show the robustness of RIMAPS and variogram analyses to detect, distinguish, and characterize leaf surfaces, as well as give scale lengths. Both techniques are tools for the biologist to study variations of the leaf surface when different patterns are present. The use of RIMAPS and variogram opens a wide spectrum of possibilities by providing a systematic, quantitative description of the leaf surface topography.

Ecological filtering and plant traits variation across quarry geomorphological surfaces: implication for restoration.

PubMed

Gilardelli, Federica; Sgorbati, Sergio; Armiraglio, Stefano; Citterio, Sandra; Gentili, Rodolfo

2015-05-01

Revegetation patterns after quarry abandonment have been widely studied from several ecological points of view, but a trait-based approach is still lacking. The aim of this study was to characterise the plant species assemblages and the associated functional traits filtered on different geomorphological surfaces in abandoned limestone quarry areas: artificial cliffs, embankments, and platforms. We then verified if species with certain traits were better able to overcome the dispersal and environmental filters necessary for establishment. To this aim, we analyzed 113 vegetation plots and collected data on 25 morphological, ecological, and dispersal traits to detect species adaptaions across these man-made environments. As a case study, we investigated the extraction basin of Botticino (Lombardy, Italy), the second largest in Italy. The results obtained by SIMPER and CCA analyses showed that rockiness, stoniness, slope, elevation, and time of surfaces are the main filters that varied across quarries and affected plant assemblages at the macro-scale level. Across the three geomorphological surfaces (meso-scale) of quarries, more specific abiotic filters selecting species were found. In turn, traits differentiation according to the three main geomorphological surfaces of quarry emphasized that further filters acting at the micro-scale imply differences in dispersal mechanisms and resource availability. This work highlighted the utility to study species assemblages and environmental filters to address quarry restoration according to the type of geomorphological surface. The investigation of some traits (chorological form, life forms, seed dispersal,s and plant height) can furnish some interesting indications for practice individuating further abiotic filters acting at the micro-scale.

A Synthesis and Comparison of Approaches for Quantifying Coral Reef Structure

NASA Astrophysics Data System (ADS)

Duvall, M. S.; Hench, J. L.

2016-02-01

The complex physical structures of coral reefs provide substrate for benthic organisms, surface area for material fluxes, and have been used as a predictor of reef-fish biomass and biodiversity. Coral reef topography has a first order effect on reef hydrodynamics by imposing drag forces and increasing momentum and scalar dispersion. Despite its importance, quantifying reef topography remains a challenge, as it is patchy and discontinuous while also varying over orders of magnitude in spatial scale. Previous studies have quantified reef structure using a range of 1D and 2D metrics that estimate vertical roughness, which is the departure from a flat geometric profile or surface. However, there is no general mathematical or conceptual framework by which to apply or compare these roughness metrics. While the specific calculations of different metrics vary, we propose that they can be classified into four categories based on: 1) vertical relief relative to a reference height; 2) gradients in vertical relief; 3) surface contour distance; or 4) variations in roughness with scale. We apply metrics from these four classes to idealized reef topography as well as natural reef topography data from Moorea, French Polynesia. Through the use of idealized profiles, we demonstrate the potential for reefs with different morphologies to possess the same value for some scale-dependent metrics (i.e. classes 1-3). Due to the superposition of variable-scale roughness elements in reef topography, we find that multi-scale metrics (i.e. class 4) can better characterize structural complexity by capturing surface roughness across a range of spatial scales. In particular, we provide evidence of the ability of 1D continuous wavelet transforms to detect changes in dominant roughness scales on idealized topography as well as within real reef systems.

Comparison of MODIS-derived land surface temperature with air temperature measurements

NASA Astrophysics Data System (ADS)

Georgiou, Andreas; Akçit, Nuhcan

2017-09-01

Air surface temperature is an important parameter for a wide range of applications such as agriculture, hydrology and climate change studies. Air temperature data is usually obtained from measurements made in meteorological stations, providing only limited information about spatial patterns over wide areas. The use of remote sensing data can help overcome this problem, particularly in areas with low station density, having the potential to improve the estimation of air surface temperature at both regional and global scales. Land Surface (skin) Temperatures (LST) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) sensor aboard the Terra and Aqua satellite platforms provide spatial estimates of near-surface temperature values. In this study, LST values from MODIS are compared to groundbased near surface air (Tair) measurements obtained from 14 observational stations during 2011 to 2015, covering coastal, mountainous and urban areas over Cyprus. Combining Terra and Aqua LST-8 Day and Night acquisitions into a mean monthly value, provide a large number of LST observations and a better overall agreement with Tair. Comparison between mean monthly LSTs and mean monthly Tair for all sites and all seasons pooled together yields a very high correlation and biases. In addition, the presented high standard deviation can be explained by the influence of surface heterogeneity within MODIS 1km2 grid cells, the presence of undetected clouds and the inherent difference between LST and Tair. However, MODIS LST data proved to be a reliable proxy for surface temperature and mostly for studies requiring temperature reconstruction in areas with lack of observational stations.

Human climbing with efficiently scaled gecko-inspired dry adhesives

PubMed Central

Hawkes, Elliot W.; Eason, Eric V.; Christensen, David L.; Cutkosky, Mark R.

2015-01-01

Since the discovery of the mechanism of adhesion in geckos, many synthetic dry adhesives have been developed with desirable gecko-like properties such as reusability, directionality, self-cleaning ability, rough surface adhesion and high adhesive stress. However, fully exploiting these adhesives in practical applications at different length scales requires efficient scaling (i.e. with little loss in adhesion as area grows). Just as natural gecko adhesives have been used as a benchmark for synthetic materials, so can gecko adhesion systems provide a baseline for scaling efficiency. In the tokay gecko (Gekko gecko), a scaling power law has been reported relating the maximum shear stress σmax to the area A: σmax ∝ A−1/4. We present a mechanical concept which improves upon the gecko's non-uniform load-sharing and results in a nearly even load distribution over multiple patches of gecko-inspired adhesive. We created a synthetic adhesion system incorporating this concept which shows efficient scaling across four orders of magnitude of area, yielding an improved scaling power law: σmax ∝ A−1/50. Furthermore, we found that the synthetic adhesion system does not fail catastrophically when a simulated failure is induced on a portion of the adhesive. In a practical demonstration, the synthetic adhesion system enabled a 70 kg human to climb vertical glass with 140 cm2 of adhesive per hand. PMID:25411404

In-situ electrochemically active surface area evaluation of an open-cathode polymer electrolyte membrane fuel cell stack

NASA Astrophysics Data System (ADS)

Torija, Sergio; Prieto-Sanchez, Laura; Ashton, Sean J.

2016-09-01

The ability to evaluate the electrochemically active surface area (ECSA) of fuel cell electrodes is crucial toward characterising designs and component suites in-situ, particularly when evaluating component durability in endurance testing, since it is a measure of the electrode area available to take part in the fuel cell reactions. Conventional methods to obtain the ECSA using cyclic voltammetry, however, rely on potentiostats that cannot be easily scaled to simultaneously evaluate all cells in a fuel cell stack of practical size, which is desirable in fuel cell development. In-situ diagnostics of an open-cathode fuel cell stack are furthermore challenging because the cells do not each possess an enclosed cathode compartment; instead, the cathodes are rather open to the environment. Here we report on a diagnostic setup that allows the electrochemically active surface area of each cell anode or cathode in an open-cathode fuel cell stack to be evaluated in-situ and simultaneously, with high resolution and reproducibility, using an easily scalable chronopotentiometry methodology and a gas-tight stack enclosure.

To what extent does urbanisation affect fragmented grassland functioning?

PubMed

van der Walt, L; Cilliers, S S; Kellner, K; Du Toit, M J; Tongway, D

2015-03-15

Urbanisation creates altered environments characterised by increased human habitation, impermeable surfaces, artificial structures, landscape fragmentation, habitat loss, resulting in different resource loss pathways. The vulnerable Rand Highveld Grassland vegetation unit in the Tlokwe Municipal area, South Africa, has been extensively affected and transformed by urbanisation, agriculture, and mining. Grassland fragments in urban areas are often considered to be less species rich and less functional than in the more untransformed or "natural" exurban environments, and are therefore seldom a priority for conservation. Furthermore, urban grassland fragments are often being more intensely managed than exurban areas, such as consistent mowing in open urban areas. Four urbanisation measures acting as indicators for patterns and processes associated with urban areas were calculated for matrix areas surrounding each selected grassland fragment to quantify the position of each grassland remnant along an urbanisation gradient. The grassland fragments were objectively classified into two classes of urbanisation, namely "exurban" and "urban" based on the urbanisation measure values. Grazing was recorded in some exurban grasslands and mowing in some urban grassland fragments. Unmanaged grassland fragments were present in both urban and exurban areas. Fine-scale biophysical landscape function was determined by executing the Landscape Function Analysis (LFA) method. LFA assesses fine-scale landscape patchiness (entailing resource conserving potential and erosion resistance) and 11 soil surface indicators to produce three main LFA parameters (stability, infiltration, and nutrient cycling), which indicates how well a system is functioning in terms of fine-scale biophysical soil processes and characteristics. The aim of this study was to determine the effects of urbanisation and associated management practices on fine-scale biophysical landscape function of urban and exurban grassland fragments, as well as to determine the potential for the use of LFA in decision-making involving the conservation of grassland fragments. The results indicated that the occurrence, size and characteristics of vegetated patches, and especially the presence of litter abundances, were the main factors determining differences in the LFA indices. Furthermore, mowing resulted in the overall fine-scale biophysical indices being higher for some of the urban grassland fragments. This implied that it is not necessarily the influence of urbanisation entailing high or low resource conserving patchiness and patch quality, but rather the management practices associated with urban and exurban areas. Therefore, from a conservation point of view, the grassland fragments in the City of Potchefstroom are just as conservable (on a biophysical function level involving soil processes) than the more "natural" exurban grassland fragments. Copyright © 2014 Elsevier Ltd. All rights reserved.

Can biomass responses to warming at plant to ecosystem levels be predicted by leaf-level responses?

NASA Astrophysics Data System (ADS)

Xia, J.; Shao, J.; Zhou, X.; Yan, W.; Lu, M.

2015-12-01

Global warming has the profound impacts on terrestrial C processes from leaf to ecosystem scales, potentially feeding back to climate dynamics. Although numerous studies had investigated the effects of warming on C processes from leaf to plant and ecosystem levels, how leaf-level responses to warming scale up to biomass responses at plant, population, and community levels are largely unknown. In this study, we compiled a dataset from 468 papers at 300 experimental sites and synthesized the warming effects on leaf-level parameters, and plant, population and ecosystem biomass. Our results showed that responses of plant biomass to warming mainly resulted from the changed leaf area rather than the altered photosynthetic capacity. The response of ecosystem biomass to warming was weaker than those of leaf area and plant biomass. However, the scaling functions from responses of leaf area to plant biomass to warming were different in diverse forest types, but functions were similar in non-forested biomes. In addition, it is challenging to scale the biomass responses from plant up to ecosystem. These results indicated that leaf area might be the appropriate index for plant biomass response to warming, and the interspecific competition might hamper the scaling of the warming effects on plant and ecosystem levels, suggesting that the acclimation capacity of plant community should be incorporated into land surface models to improve the prediction of climate-C cycle feedback.

Spatiotemporal analysis of land use and land cover change in the Brazilian Amazon

PubMed Central

Li, Guiying; Moran, Emilio; Hetrick, Scott

2013-01-01

This paper provides a comparative analysis of land use and land cover (LULC) changes among three study areas with different biophysical environments in the Brazilian Amazon at multiple scales, from per-pixel, polygon, census sector, to study area. Landsat images acquired in the years of 1990/1991, 1999/2000, and 2008/2010 were used to examine LULC change trajectories with the post-classification comparison approach. A classification system composed of six classes – forest, savanna, other-vegetation (secondary succession and plantations), agro-pasture, impervious surface, and water, was designed for this study. A hierarchical-based classification method was used to classify Landsat images into thematic maps. This research shows different spatiotemporal change patterns, composition and rates among the three study areas and indicates the importance of analyzing LULC change at multiple scales. The LULC change analysis over time for entire study areas provides an overall picture of change trends, but detailed change trajectories and their spatial distributions can be better examined at a per-pixel scale. The LULC change at the polygon scale provides the information of the changes in patch sizes over time, while the LULC change at census sector scale gives new insights on how human-induced activities (e.g., urban expansion, roads, and land use history) affect LULC change patterns and rates. This research indicates the necessity to implement change detection at multiple scales for better understanding the mechanisms of LULC change patterns and rates. PMID:24127130

Forecasting landscape effects of Mississippi River diversions on elevation and accretion in Louisiana deltaic wetlands under future environmental uncertainty scenarios

USGS Publications Warehouse

Wang, Hongqing; Steyer, Gregory D.; Couvillion, Brady R.; John M. Rybczyk,; Beck, Holly J.; William J. Sleavin,; Ehab A. Meselhe,; Mead A. Allison,; Ronald G. Boustany,; Craig J. Fischenich,; Victor H. Rivera-Monroy,

2014-01-01

Large sediment diversions are proposed and expected to build new wetlands to alleviate the extensive wetland loss (5,000 km2) affecting coastal Louisiana during the last 78 years. Current assessment and prediction of the impacts of sediment diversions have focused on the capture and dispersal of both water and sediment on the adjacent river side and the immediate outfall marsh area. However, little is known about the effects of sediment diversions on existing wetland surface elevation and vertical accretion dynamics in the receiving basin at the landscape scale. In this study, we used a spatial wetland surface elevation model developed in support of Louisiana's 2012 Coastal Master Plan to examine such landscape-scale effects of sediment diversions. Multiple sediment diversion projects were incorporated in the model to simulate surface elevation and vertical accretion for the next 50 years (2010-2060) under two environmental (moderate and less optimistic) scenarios. Specifically, we examined landscape-scale surface elevation and vertical accretion trends under diversions with different geographical locations, diverted discharge rates, and geomorphic characteristics of the receiving basin. Model results indicate that small diversions (< 283 m3 s-1) tend to have limited effects of reducing landscape-scale elevation loss (< 3%) compared to a future without action (FWOA) condition. Large sediment diversions (> 1,500 m3 s-1) are required to achieve landscape-level benefits to promote surface elevation via vertical accretion to keep pace with rising sea level.

Assimilation of Satellite-Derived Precipitation into the Regional Atmospheric Model System (RAMS): Its Impacts on the Weather and Hydrology in the Southwest United States

NASA Astrophysics Data System (ADS)

Yi, H.; Gao, X.; Sorooshian, S.

2002-05-01

As one aspect of the study of interactions between the atmosphere, vegetation, soil, and hydrology, there has been on going efforts to assimilate soil moisture data using coupled and uncoupled land surface-atmosphere hydrology models. The assimilation of soil moisture is expected to have influence due to its vital function in regulating runoff, partitioning latent and sensible heat, and through determining groundwater recharge. Soil moisture can provides long-term memory or persistence of the surface boundary condition, influencing large-scale atmospheric circulation over subsequent intervals. Now that the application of satellite remote sensing has become obvious to provide input parameters associated with land surface processes to the numerical models, this study utilizes remotely sensed precipitation data, PERSIANN (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks) to assimilate soil moisture and other soil surface characteristics. Compared to the other earlier modeling experiments of seasonal or interannual temporal scale in continental or global spatial scale, this study investigates short term predictability in regional scale with the southwest United States as a study area, which has unique metrological and geographical features that provide special difficulties for mesoscale modeling. Research objectives are to assimilate the PERSIANN precipitation data into the mesoscale model for model initialization, examine the influence and memory of model precipitation errors on the land surface and atmospheric processes, and thereby study the short term predictability of meteorology and hydrology in the Southwest United States.

Crystal Face Distributions and Surface Site Densities of Two Synthetic Goethites: Implications for Adsorption Capacities as a Function of Particle Size.

PubMed

Livi, Kenneth J T; Villalobos, Mario; Leary, Rowan; Varela, Maria; Barnard, Jon; Villacís-García, Milton; Zanella, Rodolfo; Goodridge, Anna; Midgley, Paul

2017-09-12

Two synthetic goethites of varying crystal size distributions were analyzed by BET, conventional TEM, cryo-TEM, atomic resolution STEM and HRTEM, and electron tomography in order to determine the effects of crystal size, shape, and atomic scale surface roughness on their adsorption capacities. The two samples were determined by BET to have very different site densities based on Cr VI adsorption experiments. Model specific surface areas generated from TEM observations showed that, based on size and shape, there should be little difference in their adsorption capacities. Electron tomography revealed that both samples crystallized with an asymmetric {101} tablet habit. STEM and HRTEM images showed a significant increase in atomic-scale surface roughness of the larger goethite. This difference in roughness was quantified based on measurements of relative abundances of crystal faces {101} and {201} for the two goethites, and a reactive surface site density was calculated for each goethite. Singly coordinated sites on face {210} are 2.5 more dense than on face {101}, and the larger goethite showed an average total of 36% {210} as compared to 14% for the smaller goethite. This difference explains the considerably larger adsorption capacitiy of the larger goethite vs the smaller sample and points toward the necessity of knowing the atomic scale surface structure in predicting mineral adsorption processes.

A Small-scale Model to Assess the Risk of Leachables from Single-use Bioprocess Containers through Protein Quality Characterization.

PubMed

Xiao, Nina J; Medley, Colin D; Shieh, Ian C; Downing, Gregory; Pizarro, Shelly; Liu, Jun; Patel, Ankit R

Leachables from single-use bioprocess containers (BPCs) are a source of process-related impurities that have the potential to alter product quality of biotherapeutics and affect patient health. Leachables often exist at very low concentrations, making it difficult to detect their presence and challenging to assess their impact on protein quality. A small-scale stress model based on assessing protein stability was developed to evaluate the potential risks associated with storing biotherapeutics in disposable bags caused by the presence of leachables. Small-scale BPCs were filled with protein solution at high surface area-to-volume ratios (≥3× the surface area-to-volume ratio of manufacturing-scale BPCs) and incubated at stress temperatures (e.g., 25 °C or 30 °C for up to 12 weeks) along with an appropriate storage vessel (e.g., glass vial or stainless steel) as a control for side-by-side comparison. Changes in protein size variants measured by size exclusion chromatography, capillary electrophoresis, and particle formation for two monoclonal antibodies using both the small-scale stress model and a control revealed a detrimental effect of gamma-irradiated BPCs on protein aggregation and significant BPC difference between earlier and later batches. It was found that preincubation of the empty BPCs prior to protein storage improved protein stability, suggesting the presence of volatile or heat-sensitive leachables (heat-labile or thermally degraded). In addition, increasing the polysorbate 20 concentration lowered, but did not completely mitigate, the leachable-protein interactions, indicating the presence of a hydrophobic leachable. Overall, this model can inform the risk of BPC leachables on biotherapeutics during routine manufacturing and assist in making decisions on the selection of a suitable BPC for the manufacturing process by assessing changes in product quality. Leachables from single-use systems often exist in small quantities and are difficult to detect with existing analytical methods. The presence of relevant detrimental leachables from single-use bioprocess containers (BPCs) can be indirectly detected by studying the stability of monoclonal antibodies via changes by size exclusion chromatography, capillary electrophoresis sodium dodecyl sulfate, and visible/sub-visible particles using a small-scale stress model containing high surface area-to-volume ratio at elevated temperature alongside with an appropriate control (e.g., glass vials or stainless steel containers). These changes in protein quality attributes allowed the evaluation of potential risks associated with adopting single-use bioprocess containers for storage as well as bag quality and bag differences between earlier and later batches. These leachables appear to be generated during the bag sterilization process by gamma irradiation. Improvements in protein stability after storage in "preheated" bags indicated that these leachables may be thermally unstable or volatile. The effect of surfactant levels, storage temperatures, surface area-to-volume ratios, filtration, and buffer exchange on leachables and protein stability were also assessed. © PDA, Inc. 2016.

Simulation of the Regional Ground-Water-Flow System and Ground-Water/Surface-Water Interaction in the Rock River Basin, Wisconsin

USGS Publications Warehouse

Juckem, Paul F.

2009-01-01

A regional, two-dimensional, areal ground-water-flow model was developed to simulate the ground-water-flow system and ground-water/surface-water interaction in the Rock River Basin. The model was developed by the U.S. Geological Survey (USGS), in cooperation with the Rock River Coalition. The objectives of the regional model were to improve understanding of the ground-water-flow system and to develop a tool suitable for evaluating the effects of potential regional water-management programs. The computer code GFLOW was used because of the ease with which the model can simulate ground-water/surface-water interactions, provide a framework for simulating regional ground-water-flow systems, and be refined in a stepwise fashion to incorporate new data and simulate ground-water-flow patterns at multiple scales. The ground-water-flow model described in this report simulates the major hydrogeologic features of the modeled area, including bedrock and surficial aquifers, ground-water/surface-water interactions, and ground-water withdrawals from high-capacity wells. The steady-state model treats the ground-water-flow system as a single layer with hydraulic conductivity and base elevation zones that reflect the distribution of lithologic groups above the Precambrian bedrock and a regionally significant confining unit, the Maquoketa Formation. In the eastern part of the Basin where the shale-rich Maquoketa Formation is present, deep ground-water flow in the sandstone aquifer below the Maquoketa Formation was not simulated directly, but flow into this aquifer was incorporated into the GFLOW model from previous work in southeastern Wisconsin. Recharge was constrained primarily by stream base-flow estimates and was applied uniformly within zones guided by regional infiltration estimates for soils. The model includes average ground-water withdrawals from 1997 to 2006 for municipal wells and from 1997 to 2005 for high-capacity irrigation, industrial, and commercial wells. In addition, the model routes tributary base flow through the river network to the Rock River. The parameter-estimation code PEST was linked to the GFLOW model to select the combination of parameter values best able to match more than 8,000 water-level measurements and base-flow estimates at 9 streamgages. Results from the calibrated GFLOW model show simulated (1) ground-water-flow directions, (2) ground-water/surface-water interactions, as depicted in a map of gaining and losing river and lake sections, (3) ground-water contributing areas for selected tributary rivers, and (4) areas of relatively local ground water captured by rivers. Ground-water flow patterns are controlled primarily by river geometries, with most river sections gaining water from the ground-water-flow system; losing sections are most common on the downgradient shore of lakes and reservoirs or near major pumping centers. Ground-water contributing areas to tributary rivers generally coincide with surface watersheds; however the locations of ground-water divides are controlled by the water table, whereas surface-water divides are controlled by surface topography. Finally, areas of relatively local ground water captured by rivers generally extend upgradient from rivers but are modified by the regional flow pattern, such that these areas tend to shift toward regional ground-water divides for relatively small rivers. It is important to recognize the limitations of this regional-scale model. Heterogeneities in subsurface properties and in recharge rates are considered only at a very broad scale (miles to tens of miles). No account is taken of vertical variations in properties or pumping rates, and no provision is made to account for stacked ground-water-flow systems that have different flow patterns at different depths. Small-scale flow systems (hundreds to thousands of feet) associated with minor water bodies are not considered; as a result, the model is not currently designed for simulating site-specifi

Feature pruning by upstream drainage area to support automated generalization of the United States National Hydrography Dataset

USGS Publications Warehouse

Stanislawski, L.V.

2009-01-01

The United States Geological Survey has been researching generalization approaches to enable multiple-scale display and delivery of geographic data. This paper presents automated methods to prune network and polygon features of the United States high-resolution National Hydrography Dataset (NHD) to lower resolutions. Feature-pruning rules, data enrichment, and partitioning are derived from knowledge of surface water, the NHD model, and associated feature specification standards. Relative prominence of network features is estimated from upstream drainage area (UDA). Network and polygon features are pruned by UDA and NHD reach code to achieve a drainage density appropriate for any less detailed map scale. Data partitioning maintains local drainage density variations that characterize the terrain. For demonstration, a 48 subbasin area of 1:24 000-scale NHD was pruned to 1:100 000-scale (100 K) and compared to a benchmark, the 100 K NHD. The coefficient of line correspondence (CLC) is used to evaluate how well pruned network features match the benchmark network. CLC values of 0.82 and 0.77 result from pruning with and without partitioning, respectively. The number of polygons that remain after pruning is about seven times that of the benchmark, but the area covered by the polygons that remain after pruning is only about 10% greater than the area covered by benchmark polygons. ?? 2009.

Multi-scale enhancement of climate prediction over land by increasing the model sensitivity to vegetation variability in EC-Earth

NASA Astrophysics Data System (ADS)

Alessandri, Andrea; Catalano, Franco; De Felice, Matteo; Van Den Hurk, Bart; Doblas Reyes, Francisco; Boussetta, Souhail; Balsamo, Gianpaolo; Miller, Paul

2016-04-01

The EC-Earth earth system model has been recently developed to include the dynamics of vegetation. In its original formulation, vegetation variability is simply operated by the Leaf Area Index (LAI), which affects climate basically by changing the vegetation physiological resistance to evapotranspiration. This coupling has been found to have only a weak effect on the surface climate modeled by EC-Earth. In reality, the effective sub-grid vegetation fractional coverage will vary seasonally and at interannual time-scales in response to leaf-canopy growth, phenology and senescence. Therefore it affects biophysical parameters such as the albedo, surface roughness and soil field capacity. To adequately represent this effect in EC-Earth, we included an exponential dependence of the vegetation cover on the LAI. By comparing two sets of simulations performed with and without the new variable fractional-coverage parameterization, spanning retrospective predictions at the decadal (5-years), seasonal and sub-seasonal time-scales, we show for the first time a significant multi-scale enhancement of vegetation impacts in climate simulation and prediction over land. Particularly large effects at multiple time scales are shown over boreal winter middle-to-high latitudes over Canada, West US, Eastern Europe, Russia and eastern Siberia due to the implemented time-varying shadowing effect by tree-vegetation on snow surfaces. Over Northern Hemisphere boreal forest regions the improved representation of vegetation cover tends to correct the winter warm biases, improves the climate change sensitivity, the decadal potential predictability as well as the skill of forecasts at seasonal and sub-seasonal time-scales. Significant improvements of the prediction of 2m temperature and rainfall are also shown over transitional land surface hot spots. Both the potential predictability at decadal time-scale and seasonal-forecasts skill are enhanced over Sahel, North American Great Plains, Nordeste Brazil and South East Asia, mainly related to improved performance in the surface evapotranspiration.

Multi-scale enhancement of climate prediction over land by increasing the model sensitivity to vegetation variability in EC-Earth

NASA Astrophysics Data System (ADS)

Alessandri, A.; Catalano, F.; De Felice, M.; van den Hurk, B.; Doblas-Reyes, F. J.; Boussetta, S.; Balsamo, G.; Miller, P. A.

2016-12-01

The European consortium earth system model (EC-Earth; http://www.ec-earth.org) has been recently developed to include the dynamics of vegetation. In its original formulation, vegetation variability is simply operated by the Leaf Area Index (LAI), which affects climate basically by changing the vegetation physiological resistance to evapotranspiration. This coupling has been found to have only a weak effect on the surface climate modeled by EC-Earth. In reality, the effective sub-grid vegetation fractional coverage will vary seasonally and at interannual time-scales in response to leaf-canopy growth, phenology and senescence. Therefore it affects biophysical parameters such as the albedo, surface roughness and soil field capacity. To adequately represent this effect in EC-Earth, we included an exponential dependence of the vegetation cover on the LAI. By comparing two sets of simulations performed with and without the new variable fractional-coverage parameterization, spanning from centennial (20th Century) simulations and retrospective predictions to the decadal (5-years), seasonal and weather time-scales, we show for the first time a significant multi-scale enhancement of vegetation impacts in climate simulation and prediction over land. Particularly large effects at multiple time scales are shown over boreal winter middle-to-high latitudes over Canada, West US, Eastern Europe, Russia and eastern Siberia due to the implemented time-varying shadowing effect by tree-vegetation on snow surfaces. Over Northern Hemisphere boreal forest regions the improved representation of vegetation cover tends to correct the winter warm biases, improves the climate change sensitivity, the decadal potential predictability as well as the skill of forecasts at seasonal and weather time-scales. Significant improvements of the prediction of 2m temperature and rainfall are also shown over transitional land surface hot spots. Both the potential predictability at decadal time-scale and seasonal-forecasts skill are enhanced over Sahel, North American Great Plains, Nordeste Brazil and South East Asia, mainly related to improved performance in the surface evapotranspiration.

Multi-scale enhancement of climate prediction over land by increasing the model sensitivity to vegetation variability in EC-Earth

NASA Astrophysics Data System (ADS)

Alessandri, Andrea; Catalano, Franco; De Felice, Matteo; Van Den Hurk, Bart; Doblas Reyes, Francisco; Boussetta, Souhail; Balsamo, Gianpaolo; Miller, Paul A.

2017-08-01

The EC-Earth earth system model has been recently developed to include the dynamics of vegetation. In its original formulation, vegetation variability is simply operated by the Leaf Area Index (LAI), which affects climate basically by changing the vegetation physiological resistance to evapotranspiration. This coupling has been found to have only a weak effect on the surface climate modeled by EC-Earth. In reality, the effective sub-grid vegetation fractional coverage will vary seasonally and at interannual time-scales in response to leaf-canopy growth, phenology and senescence. Therefore it affects biophysical parameters such as the albedo, surface roughness and soil field capacity. To adequately represent this effect in EC-Earth, we included an exponential dependence of the vegetation cover on the LAI. By comparing two sets of simulations performed with and without the new variable fractional-coverage parameterization, spanning from centennial (twentieth century) simulations and retrospective predictions to the decadal (5-years), seasonal and weather time-scales, we show for the first time a significant multi-scale enhancement of vegetation impacts in climate simulation and prediction over land. Particularly large effects at multiple time scales are shown over boreal winter middle-to-high latitudes over Canada, West US, Eastern Europe, Russia and eastern Siberia due to the implemented time-varying shadowing effect by tree-vegetation on snow surfaces. Over Northern Hemisphere boreal forest regions the improved representation of vegetation cover tends to correct the winter warm biases, improves the climate change sensitivity, the decadal potential predictability as well as the skill of forecasts at seasonal and weather time-scales. Significant improvements of the prediction of 2 m temperature and rainfall are also shown over transitional land surface hot spots. Both the potential predictability at decadal time-scale and seasonal-forecasts skill are enhanced over Sahel, North American Great Plains, Nordeste Brazil and South East Asia, mainly related to improved performance in the surface evapotranspiration.

Multi-scale enhancement of climate prediction over land by increasing the model sensitivity to vegetation variability in EC-Earth

NASA Astrophysics Data System (ADS)

Alessandri, Andrea; Catalano, Franco; De Felice, Matteo; Van Den Hurk, Bart; Doblas Reyes, Francisco; Boussetta, Souhail; Balsamo, Gianpaolo; Miller, Paul A.

2017-04-01

The EC-Earth earth system model has been recently developed to include the dynamics of vegetation. In its original formulation, vegetation variability is simply operated by the Leaf Area Index (LAI), which affects climate basically by changing the vegetation physiological resistance to evapotranspiration. This coupling has been found to have only a weak effect on the surface climate modeled by EC-Earth. In reality, the effective sub-grid vegetation fractional coverage will vary seasonally and at interannual time-scales in response to leaf-canopy growth, phenology and senescence. Therefore it affects biophysical parameters such as the albedo, surface roughness and soil field capacity. To adequately represent this effect in EC-Earth, we included an exponential dependence of the vegetation cover on the LAI. By comparing two sets of simulations performed with and without the new variable fractional-coverage parameterization, spanning from centennial (20th Century) simulations and retrospective predictions to the decadal (5-years), seasonal and weather time-scales, we show for the first time a significant multi-scale enhancement of vegetation impacts in climate simulation and prediction over land. Particularly large effects at multiple time scales are shown over boreal winter middle-to-high latitudes over Canada, West US, Eastern Europe, Russia and eastern Siberia due to the implemented time-varying shadowing effect by tree-vegetation on snow surfaces. Over Northern Hemisphere boreal forest regions the improved representation of vegetation cover tends to correct the winter warm biases, improves the climate change sensitivity, the decadal potential predictability as well as the skill of forecasts at seasonal and weather time-scales. Significant improvements of the prediction of 2m temperature and rainfall are also shown over transitional land surface hot spots. Both the potential predictability at decadal time-scale and seasonal-forecasts skill are enhanced over Sahel, North American Great Plains, Nordeste Brazil and South East Asia, mainly related to improved performance in the surface evapotranspiration.

Urban thermal environment and its biophysical parameters derived from satellite remote sensing imagery

NASA Astrophysics Data System (ADS)

Zoran, Maria A.; Savastru, Roxana S.; Savastru, Dan M.; Tautan, Marina N.; Baschir, Laurentiu V.

2013-10-01

In frame of global warming, the field of urbanization and urban thermal environment are important issues among scientists all over the world. This paper investigated the influences of urbanization on urban thermal environment as well as the relationships of thermal characteristics to other biophysical variables in Bucharest metropolitan area of Romania based on satellite remote sensing imagery Landsat TM/ETM+, time series MODIS Terra/Aqua data and IKONOS acquired during 1990 - 2012 period. Vegetation abundances and percent impervious surfaces were derived by means of linear spectral mixture model, and a method for effectively enhancing impervious surface has been developed to accurately examine the urban growth. The land surface temperature (Ts), a key parameter for urban thermal characteristics analysis, was also retrieved from thermal infrared band of Landsat TM/ETM+, from MODIS Terra/Aqua datasets. Based on these parameters, the urban growth, urban heat island effect (UHI) and the relationships of Ts to other biophysical parameters have been analyzed. Results indicated that the metropolitan area ratio of impervious surface in Bucharest increased significantly during two decades investigated period, the intensity of urban heat island and heat wave events being most significant. The correlation analyses revealed that, at the pixel-scale, Ts possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at the regional scale, respectively. This analysis provided an integrated research scheme and the findings can be very useful for urban ecosystem modeling.

Spatial variations in drainage efficiency in a boreal wetland environment as a function of lidar and radar-derived deviations from the regional hydraulic gradient

NASA Astrophysics Data System (ADS)

Hopkinson, C.; Brisco, B.; Chasmer, L.; Devito, K.; Montgomery, J. S.; Patterson, S.; Petrone, R. M.

2017-12-01

The dense forest cover of the Western Boreal Plains of northern Alberta is underlain by a mix of glacial moraines, sandy outwash sediments and clay plains possessing spatially variable hydraulic conductivities. The region is also characterised by a large number of post-glacial surface depression wetlands that have seasonally and topographically limited surface connectivity. Consequently, drainage along shallow regional hydraulic gradients may be dominated either by variations in surface geology or local variations in Et. Long-term government lake level monitoring is sparse in this region, but over a decade of hydrometeorological monitoring has taken place around the Utikuma Regional Study Area (URSA), a research site led by the University of Alberta. In situ lake and ground water level data are here combined with time series of airborne lidar and RadarSat II synthetic aperture radar (SAR) data to assess the spatial variability of water levels during late summer period characterised by flow recession. Long term Lidar data were collected or obtained by the authors in August of 2002, 2008, 2011 and 2016, while seasonal SAR data were captured approximately every 24 days during the summers of 2015, 2016 and 2017. Water levels for wetlands exceeding 100m2 in area across a north-trending 20km x 5km topographic gradient north of Utikuma Lake were extracted directly from the lidar and indirectly from the SAR. The recent seasonal variability in spatial water levels was extracted from SAR, while the lidar data illustrated more long term trends associated with land use and riparian vegetation succession. All water level data collected in August were combined and averaged at multiple scales using a raster focal statistics function to generate a long term spatial map of the regional hydraulic gradient and scale-dependent variations. Areas of indicated high and low drainage efficiency were overlain onto layers of landcover and surface geology to ascertain causal relationships. Areas associated with high spatial variability in water level illustrate reduced drainage connectivity, while areas of reduced variability indicate high surface connectivity and/or hydraulic conductivity. The hypothesis of surface geology controls on local wetland connectivity and landscape drainage efficiency is supported through this analysis.

Assessing the impact of future land use and land cover changes on climate over Brazilian semiarid

NASA Astrophysics Data System (ADS)

Cunha, A. M.; Alvalá, R. S.; Kubota, P. Y.; Vieira, R.

2013-12-01

The continental surface vegetal cover has been considerably changed by human activities, mainly through natural vegetation conversion in grasslands. Such changes in surface cover may impact the regional and global climates, through of the changes in biophysical processes and CO2 exchanges between vegetation and atmosphere. In recent decades, most of the Brazilian territory has been presenting transformation in the land use/cover spatial patterns. The typical vegetation of the Brazilian semiarid, known as caatinga (closed shrubland) had been replaced by pasture lands. Based on that, the main objective of this work was to investigate the impacts of future land cover and land use changes (LCLUC) on surface processes and on the climate of Brazilian semiarid region. Numerical experiments using the AGCM/CPTEC/IBIS were performed in order to investigate the impacts of LCLUC on the climate of Brazilian semiarid due to the replacement of natural vegetation by pasture and degraded areas. The climate impacts of LUCC were assessed using climate simulations considering two scenarios of vegetation distribution: i) Potential Vegetation (Control) and ii) Future scenario of the vegetation: maximum pasture limited by areas of desert and semidesert. These degraded areas were obtained from the future projection of the biome distribution in South America developed by Salazar Velasquez (2009) using CPTEC PVMReg and emission scenarios A2 of the Intergovernmental Panel on Climate Change (IPCC). In general, the simulation results showed that the LCLUC, due to the changes in relevant surface variables, has caused alterations in local and neighborhood regions climate. The LCLUC leads to a decrease in mean rainfall during dry season at study area. A meridional dipole pattern with near surface temperature increase (reduction) in the northern (southern) areas of semiarid was found. The results also highlight that LUCC led to changes in the components of the surface energy and carbon balance. These results suggest that LCLUC, even on a small scale in Brazil's semiarid region, can cause climate impacts, in local and regional scale. Finally, we highlight that the diagnosis of the evolution of LUCC and its climatic implications are essential to guide policy makers in regard to resources application and on policies development, in order to achieve a better management and planning for this important region of the country.

Regular Nanoscale Protein Patterns via Directed Adsorption through Self-Assembled DNA Origami Masks.

PubMed

Ramakrishnan, Saminathan; Subramaniam, Sivaraman; Stewart, A Francis; Grundmeier, Guido; Keller, Adrian

2016-11-16

DNA origami has become a widely used method for synthesizing well-defined nanostructures with promising applications in various areas of nanotechnology, biophysics, and medicine. Recently, the possibility to transfer the shape of single DNA origami nanostructures into different materials via molecular lithography approaches has received growing interest due to the great structural control provided by the DNA origami technique. Here, we use ordered monolayers of DNA origami nanostructures with internal cavities on mica surfaces as molecular lithography masks for the fabrication of regular protein patterns over large surface areas. Exposure of the masked sample surface to negatively charged proteins results in the directed adsorption of the proteins onto the exposed surface areas in the holes of the mask. By controlling the buffer and adsorption conditions, the protein coverage of the exposed areas can be varied from single proteins to densely packed monolayers. To demonstrate the versatility of this approach, regular nanopatterns of four different proteins are fabricated: the single-strand annealing proteins Redβ and Sak, the iron-storage protein ferritin, and the blood protein bovine serum albumin (BSA). We furthermore demonstrate the desorption of the DNA origami mask after directed protein adsorption, which may enable the fabrication of hierarchical patterns composed of different protein species. Because selectivity in adsorption is achieved by electrostatic interactions between the proteins and the exposed surface areas, this approach may enable also the large-scale patterning of other charged molecular species or even nanoparticles.

In-situ upgrading of biomass pyrolysis vapors: catalyst screening on a fixed bed reactor.

PubMed

Stefanidis, S D; Kalogiannis, K G; Iliopoulou, E F; Lappas, A A; Pilavachi, P A

2011-09-01

In-situ catalytic upgrading of biomass fast pyrolysis vapors was performed in a fixed bed bench-scale reactor at 500°C, for catalyst screening purposes. The catalytic materials tested include a commercial equilibrium FCC catalyst (E-cat), various commercial ZSM-5 formulations, magnesium oxide and alumina materials with varying specific surface areas, nickel monoxide, zirconia/titania, tetragonal zirconia, titania and silica alumina. The bio-oil was characterized measuring its water content, the carbon-hydrogen-oxygen (by difference) content and the chemical composition of its organic fraction. Each catalytic material displayed different catalytic effects. High surface area alumina catalysts displayed the highest selectivity towards hydrocarbons, yielding however low organic liquid products. Zirconia/titania exhibited good selectivity towards desired compounds, yielding higher organic liquid product than the alumina catalysts. The ZSM-5 formulation with the highest surface area displayed the most balanced performance having a moderate selectivity towards hydrocarbons, reducing undesirable compounds and producing organic liquid products at acceptable yields. Copyright © 2011 Elsevier Ltd. All rights reserved.

Hierarchically Porous Graphitic Carbon with Simultaneously High Surface Area and Colossal Pore Volume Engineered via Ice Templating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Estevez, Luis; Prabhakaran, Venkateshkumar; Garcia, Adam L.

Developing hierarchical porous carbon (HPC) materials with competing textural characteristics such as surface area and pore volume in one material is difficult to accomplish—particulalry for an atomically ordered (graphitic) carbon. Herein we describe a synthesis strategy to engineer tunable hierarchically porous carbon (HPC) materials across micro- meso- and macroporous length scales, allowing the fabrication of a graphitic HPC with both very high surface area (> 2500 m2/g) and pore volume (>10 cm3/g), the combination of which has not been seen previously. The mesopore volume alone for these materials is up to 7.91 cm3/g, the highest ever reported. The unique materialmore » was explored for use as a supercapaictor electrode and for oil adsorption; two applications that require textural properties that are typicaly exclusive to one another. This design scheme for HPCs can be utilized in broad applications, including electrochemical systems such as batteries and supercapacitors, sorbents, and catalyst supports.« less

Microwave-Assisted Synthesis of Highly-Crumpled, Few-Layered Graphene and Nitrogen-Doped Graphene for Use as High-Performance Electrodes in Capacitive Deionization

NASA Astrophysics Data System (ADS)

Amiri, Ahmad; Ahmadi, Goodarz; Shanbedi, Mehdi; Savari, Maryam; Kazi, S. N.; Chew, B. T.

2015-12-01

Capacitive deionization (CDI) is a promising procedure for removing various charged ionic species from brackish water. The performance of graphene-based material in capacitive deionization is lower than the expectation of the industry, so highly-crumpled, few-layered graphene (HCG) and highly-crumpled nitrogen-doped graphene (HCNDG) with high surface area have been introduced as promising candidates for CDI electrodes. Thus, HCG and HCNDG were prepared by exfoliation of graphite in the presence of liquid-phase, microwave-assisted methods. An industrially-scalable, cost-effective, and simple approach was employed to synthesize HCG and HCNDG, resulting in few-layered graphene and nitrogen-doped graphene with large specific surface area. Then, HCG and HCNDG were utilized for manufacturing a new class of carbon nanostructure-based electrodes for use in large-scale CDI equipment. The electrosorption results indicated that both the HCG and HCNDG have fairly large specific surface areas, indicating their huge potential for capacitive deionization applications.

Influence of multi-scale hydrologic controls on river network connectivity and riparian function

EPA Science Inventory

The ecological functions of rivers and streams and their associated riparian zones are strongly influenced by surface and subsurface hydrologic routing of water within river basins and river networks. Hydrologic attributes of the riparian area for a given stream reach are typica...

Compound cooling flow turbulator for turbine component

DOEpatents

Lee, Ching-Pang; Jiang, Nan; Marra, John J; Rudolph, Ronald J

2014-11-25

Multi-scale turbulation features, including first turbulators (46, 48) on a cooling surface (44), and smaller turbulators (52, 54, 58, 62) on the first turbulators. The first turbulators may be formed between larger turbulators (50). The first turbulators may be alternating ridges (46) and valleys (48). The smaller turbulators may be concave surface features such as dimples (62) and grooves (54), and/or convex surface features such as bumps (58) and smaller ridges (52). An embodiment with convex turbulators (52, 58) in the valleys (48) and concave turbulators (54, 62) on the ridges (46) increases the cooling surface area, reduces boundary layer separation, avoids coolant shadowing and stagnation, and reduces component mass.

Laser-induced periodic structures for light extraction efficiency enhancement of GaN-based light emitting diodes.

PubMed

Chen, Jiun-Ting; Lai, Wei-Chih; Kao, Yu-Jui; Yang, Ya-Yu; Sheu, Jinn-Kong

2012-02-27

The laser-induced periodic surface structure technique was used to form simultaneously dual-scale rough structures (DSRS) with spiral-shaped nanoscale structure inside semi-spherical microscale holes on p-GaN surface to improve the light-extraction efficiency of light-emitting diodes (LEDs). The light output power of DSRS-LEDs was 30% higher than that of conventional LEDs at an injection current of 20 mA. The enhancement in the light output power could be attributed to the increase in the probability of photons to escape from the increased surface area of textured p-GaN surface.

Moisture harvesting and water transport through specialized micro-structures on the integument of lizards

PubMed Central

Comanns, Philipp; Effertz, Christian; Hischen, Florian; Staudt, Konrad; Böhme, Wolfgang

2011-01-01

Summary Several lizard species that live in arid areas have developed special abilities to collect water with their bodies' surfaces and to ingest the so collected moisture. This is called rain- or moisture-harvesting. The water can originate from air humidity, fog, dew, rain or even from humid soil. The integument (i.e., the skin plus skin derivatives such as scales) has developed features so that the water spreads and is soaked into a capillary system in between the reptiles' scales. Within this capillary system the water is transported to the mouth where it is ingested. We have investigated three different lizard species which have developed the ability for moisture harvesting independently, viz. the Australian thorny devil (Moloch horridus), the Arabian toadhead agama (Phrynocephalus arabicus) and the Texas horned lizard (Phrynosoma cornutum). All three lizards have a honeycomb like micro ornamentation on the outer surface of the scales and a complex capillary system in between the scales. By investigation of individual scales and by producing and characterising polymer replicas of the reptiles' integuments, we found that the honeycomb like structures render the surface superhydrophilic, most likely by holding a water film physically stable. Furthermore, the condensation of air humidity is improved on this surface by about 100% in comparison to unstructured surfaces. This allows the animals to collect moisture with their entire body surface. The collected water is transported into the capillary system. For Phrynosoma cornutum we found the interesting effect that, in contrast to the other two investigated species, the water flow in the capillary system is not uniform but directed to the mouth. Taken together we found that the micro ornamentation yields a superhydrophilic surface, and the semi-tubular capillaries allow for an efficient passive – and for Phrynosoma directed – transport of water. PMID:21977432

Characterizing TPS Microstructure: A Review of Some techniques

NASA Technical Reports Server (NTRS)

Gasch, Matthew; Stackpole, Mairead; Agrawal, Parul; Chavez-Garcie, Jose

2011-01-01

I. When seeking to understand ablator microstructure and morphology there are several useful techniques A. SEM 1) Visual characteriza3on at various length scales. 2) Chemical mapping by backscatter or x-ray highlights areas of interest. 3) Combined with other techniques (density, weight change, chemical analysis) SEM is a powerful tool to aid in explaining thermo/structural data. B. ASAP. 1) Chemical characteriza3on at various length scales. 2) Chemical mapping of pore structure by gas adsorption. 3) Provides a map of pore size vs. pore volume. 4) Provided surface area of exposed TPS. II. Both methods help characterize and understand how ablators react with other chemical species and provides insight into how they oxidize.

Applicability of Macroscopic Wear and Friction Laws on the Atomic Length Scale.

PubMed

Eder, S J; Feldbauer, G; Bianchi, D; Cihak-Bayr, U; Betz, G; Vernes, A

2015-07-10

Using molecular dynamics, we simulate the abrasion process of an atomically rough Fe surface with multiple hard abrasive particles. By quantifying the nanoscopic wear depth in a time-resolved fashion, we show that Barwell's macroscopic wear law can be applied at the atomic scale. We find that in this multiasperity contact system, the Bowden-Tabor term, which describes the friction force as a function of the real nanoscopic contact area, can predict the kinetic friction even when wear is involved. From this the Derjaguin-Amontons-Coulomb friction law can be recovered, since we observe a linear dependence of the contact area on the applied load in accordance with Greenwood-Williamson contact mechanics.

Exploring the Validity Range of the Polarimetric Two-Scale Two-Component Model for Soil Moisture Retrieval by Using AGRISAR Data

NASA Astrophysics Data System (ADS)

Di Martino, Gerardo; Iodice, Antonio; Natale, Antonio; Riccio, Daniele; Ruello, Giuseppe

2015-04-01

The recently proposed polarimetric two-scale two- component model (PTSTCM) in principle allows us obtaining a reasonable estimation of the soil moisture even in moderately vegetated areas, where the volumetric scattering contribution is non-negligible, provided that the surface component is dominant and the double-bounce component is negligible. Here we test the PTSTCM validity range by applying it to polarimetric SAR data acquired on areas for which, at the same times of SAR acquisitions, ground measurements of soil moisture were performed. In particular, we employ the AGRISAR'06 database, which includes data from several fields covering a period that spans all the phases of vegetation growth.

The geometry of folds in granitoid rocks of northeastern Alberta

NASA Astrophysics Data System (ADS)

Willem Langenberg, C.; Ramsden, John

1980-06-01

Granitoid rocks which predominate in the Precambrian shield of northeastern Alberta show large-scale fold structures. A numerical procedure has been used to obtain modal foliation orientations. This procedure results in the smoothing of folded surfaces that show roughness on a detailed scale. Statistical tests are used to divide the study areas into cylindrical domains. Structural sections can be obtained for each domain, and horizontal and vertical sections are used to construct block diagrams. The projections are performed numerically and plotted by computer. This method permits blocks to be viewed from every possible angle. Both perspective and orthographic projections can be produced. The geometries of a dome in the Tulip Lake area and a synform in the Hooker Lake area have been obtained. The domal structure is compared with polyphase deformational interference patterns and with experimental diapiric structures obtained in a centrifuge system. The synform in the Hooker Lake area may be genetically related to the doming in the Tulip Lake area.

Ocean Winds and Turbulent Air-Sea Fluxes Inferred From Remote Sensing

NASA Technical Reports Server (NTRS)

Bourassa, Mark A.; Gille, Sarah T.; Jackson, Daren L.; Roberts, J. Brent; Wick, Gary A.

2010-01-01

Air-sea turbulent fluxes determine the exchange of momentum, heat, freshwater, and gas between the atmosphere and ocean. These exchange processes are critical to a broad range of research questions spanning length scales from meters to thousands of kilometers and time scales from hours to decades. Examples are discussed (section 2). The estimation of surface turbulent fluxes from satellite is challenging and fraught with considerable errors (section 3); however, recent developments in retrievals (section 3) will greatly reduce these errors. Goals for the future observing system are summarized in section 4. Surface fluxes are defined as the rate per unit area at which something (e.g., momentum, energy, moisture, or CO Z ) is transferred across the air/sea interface. Wind- and buoyancy-driven surface fluxes are called surface turbulent fluxes because the mixing and transport are due to turbulence. Examples of nonturbulent processes are radiative fluxes (e.g., solar radiation) and precipitation (Schmitt et al., 2010). Turbulent fluxes are strongly dependent on wind speed; therefore, observations of wind speed are critical for the calculation of all turbulent surface fluxes. Wind stress, the vertical transport of horizontal momentum, also depends on wind direction. Stress is very important for many ocean processes, including upper ocean currents (Dohan and Maximenko, 2010) and deep ocean currents (Lee et al., 2010). On short time scales, this horizontal transport is usually small compared to surface fluxes. For long-term processes, transport can be very important but again is usually small compared to surface fluxes.

Center for Quantum Algorithms and Complexity

DTIC Science & Technology

2014-05-12

precisely, it asserts that for any subset L of particles, the entanglement entropy between L and L̄ is bounded by the surface area of L (the area is...ground states of gapped local Hamiltonians. Roughly, it says that the entanglement in such states is very local, and the entanglement entropy scales...the theorem states that the entanglement entropy is bounded by exp(X), where X = log(d/?). Hastingss result implies that ground states of gapped 1D

Remote sensing applied to prospecting of thermomineral water in the county of Caldas Novas-Goias

NASA Technical Reports Server (NTRS)

Veneziani, P.; Eustaquiodosanjos, C.

1978-01-01

LANDSAT imagery of the region were studied allowing the placement of the area of study in the regional geological context. A geological mapping of the 1.60.000 scale was done. A methodology was developed which consisted in a regional temperature mapping using trend surface analysis. Through the correlation of all these data, four different areas were localized with a high potential as thermomineral sources.

Spatial scale analysis in geophysics - Integrating surface and borehole geophysics in groundwater studies

USGS Publications Warehouse

Paillet, Frederick L.; Singhroy, V.H.; Hansen, D.T.; Pierce, R.R.; Johnson, A.I.

2002-01-01

Integration of geophysical data obtained at various scales can bridge the gap between localized data from boreholes and site-wide data from regional survey profiles. Specific approaches to such analysis include: 1) comparing geophysical measurements in boreholes with the same measurement made from the surface; 2) regressing geophysical data obtained in boreholes with water-sample data from screened intervals; 3) using multiple, physically independent measurements in boreholes to develop multivariate response models for surface geophysical surveys; 4) defining subsurface cell geometry for most effective survey inversion methods; and 5) making geophysical measurements in boreholes to serve as independent verification of geophysical interpretations. Integrated analysis of surface electromagnetic surveys and borehole geophysical logs at a study site in south Florida indicates that salinity of water in the surficial aquifers is controlled by a simple wedge of seawater intrusion along the coast and by a complex pattern of upward brine seepage from deeper aquifers throughout the study area. This interpretation was verified by drilling three additional test boreholes in carefully selected locations.

Fabrication of meso- and nano-scale structures on surfaces of chalcogenide semiconductors by surface hydrodynamic interference patterning

NASA Astrophysics Data System (ADS)

Bilanych, V.; Komanicky, V.; Lacková, M.; Feher, A.; Kuzma, V.; Rizak, V.

2015-10-01

We observe the change of surface relief on amorphous Ge-As-Se thin films after irradiation with an electron beam. The beam softens the glass and induces various topological surface changes in the irradiated area. The film relief change depends on the film thickness, deposited charge, and film composition. Various structures are formed: Gausian-like cones, extremely sharp Taylor cones, deep craters, and craters with large spires grown on the side. Our investigation shows that these effects can be at least partially a result of electro-hydrodynamic material flow, but the observed phenomena are likely more complex. When we irradiated structural patterns formed by the electron beam with a red laser beam, we could not only fully relax the produced patterns, but also form very complex and intricate superstructures. These organized meso- and nano-scale structures are formed by a combination of photo-induced structural relaxation, light interference on structures fabricated by the e-beam, and photo-induced material flow.

Scaling Relations of Earthquakes on Inland Active Mega-Fault Systems

NASA Astrophysics Data System (ADS)

Murotani, S.; Matsushima, S.; Azuma, T.; Irikura, K.; Kitagawa, S.

2010-12-01

Since 2005, The Headquarters for Earthquake Research Promotion (HERP) has been publishing 'National Seismic Hazard Maps for Japan' to provide useful information for disaster prevention countermeasures for the country and local public agencies, as well as promote public awareness of disaster prevention of earthquakes. In the course of making the year 2009 version of the map, which is the commemorate of the tenth anniversary of the settlement of the Comprehensive Basic Policy, the methods to evaluate magnitude of earthquakes, to predict strong ground motion, and to construct underground structure were investigated in the Earthquake Research Committee and its subcommittees. In order to predict the magnitude of earthquakes occurring on mega-fault systems, we examined the scaling relations for mega-fault systems using 11 earthquakes of which source processes were analyzed by waveform inversion and of which surface information was investigated. As a result, we found that the data fit in between the scaling relations of seismic moment and rupture area by Somerville et al. (1999) and Irikura and Miyake (2001). We also found that maximum displacement of surface rupture is two to three times larger than the average slip on the seismic fault and surface fault length is equal to length of the source fault. Furthermore, compiled data of the source fault shows that displacement saturates at 10m when fault length(L) is beyond 100km, L>100km. By assuming the fault width (W) to be 18km in average of inland earthquakes in Japan, and the displacement saturate at 10m for length of more than 100 km, we derived a new scaling relation between source area and seismic moment, S[km^2] = 1.0 x 10^-17 M0 [Nm] for mega-fault systems that seismic moment (M0) exceeds 1.8×10^20 Nm.

Strong Control of Salts on Near Surface Liquid Water Content in a High Polar Desert Indicated by Near Surface Resistivity Mapping with a Helicopter-Borne TEM Sensor, Lower Taylor Valley, Antarctica

NASA Astrophysics Data System (ADS)

Foley, N.; Tulaczyk, S. M.; Auken, E.; Mikucki, J.; Myers, K. F.; Dugan, H.; Doran, P. T.; Virginia, R. A.

2016-12-01

Closed depressions in the Lower Taylor Valley (McMurdo Dry Valleys, Antarctica) have near surface (top 5m) electrical resistivity that is lower by about an order of magnitude than the resistivity of nearby slopes and ridges (100s of ohm-m vs. 1000s). We interpret this spatial pattern as being due to long term concentration of salts carried by liquid water and/or deliquescent vapor fronts. High concentration of salts in the top decimeters to meters beneath the surface may prolong the existence and abundance of liquid water in this otherwise very cold and dry high polar desert. Due to its connections with life and chemical transport, liquid water is a much studied feature in the McMurdo Dry Valleys. This setting can be used as an analogue for similar features on the surface of Mars, where liquid water tracks have been observed and are believed to be controlled by eutectic brines. Our study demonstrates the utility of mapping at a regional scale via helicopter-borne Transient EM. Airborne EM covers more ground and can measure deeper than surface-based measurements, at the expense of resolution. This allows creating valley-scale datasets which could not feasibly be collected on the ground. Our remote measurements complement physical samples that indicate that soluble salts concentrate in certain areas of surface soil where water moves ions and is later removed by evaporation or sublimation. In areas where we measured low resistivity, the integrated liquid water fraction in the top 5m may be a few to several percent by volume, equivalent to a few or several dozens of cm of water layer thickness. This estimate assumes that the interstitial waters have very low resistivity, comparable to seawater or hypersaline brines at freezing (0.2-0.35 ohm-m). If soil water was considerably fresher than this, liquid water content would have to reach dozens of percent throughout the top 5m for bulk resistivities to drop to 100s of ohm-m. We consider the latter case to be unlikely as the thermally defined active layer in this region with mean annual temperature close to -20C and short summer season is as thin as dozens of cm. The areas with high near-surface resistivities have either a comparable fraction of water but with much higher resistivity or have briny interstitial water at much lower volume concentrations (<1% in top 5m). We favor the former explanation. Closed depressions in the Lake Fryxell basin (McMurdo Dry Valleys, Antarctica) have near surface (top 5m) electrical resistivity that is lower by almost an order of magnitude than nearby slopes and ridges. We interpret this spatial pattern as being due to long term concentration of salts carried by liquid water and deliquescent vapor fronts. Highly hygroscopic salts may prolong the existence and abundance of liquid water in the near surface in this otherwise very cold and dry high polar desert. In areas with low measured resistivity, the liquid water fraction in the top 5m may be a few percent by volume. Due to its connections with life and chemical transport, liquid water is a much studied feature in the McMurdo Dry Valleys. This setting can be used as an analogue for similar features on the surface of Mars, where liquid water tracks have been observed and are believed to be controlled by eutectic brines. Our study demonstrates the utility of mapping at a regional scale via helicopter-borne Time Domain EM. Airborne EM covers more ground and can measure deeper than surface-based measurements, at the expense of resolution. This allows creating valley-scale datasets which could not feasibly be collected on the ground. Our remote measurements complement physical samples that indicate that soluble salts concentrate in certain areas of surface soil where water moves ions and is later removed by evaporation or sublimation.

Mapping regional patterns of large forest fires in Wildland-Urban Interface areas in Europe.

PubMed

Modugno, Sirio; Balzter, Heiko; Cole, Beth; Borrelli, Pasquale

2016-05-01

Over recent decades, Land Use and Cover Change (LUCC) trends in many regions of Europe have reconfigured the landscape structures around many urban areas. In these areas, the proximity to landscape elements with high forest fuels has increased the fire risk to people and property. These Wildland-Urban Interface areas (WUI) can be defined as landscapes where anthropogenic urban land use and forest fuel mass come into contact. Mapping their extent is needed to prioritize fire risk control and inform local forest fire risk management strategies. This study proposes a method to map the extent and spatial patterns of the European WUI areas at continental scale. Using the European map of WUI areas, the hypothesis is tested that the distance from the nearest WUI area is related to the forest fire probability. Statistical relationships between the distance from the nearest WUI area, and large forest fire incidents from satellite remote sensing were subsequently modelled by logistic regression analysis. The first European scale map of the WUI extent and locations is presented. Country-specific positive and negative relationships of large fires and the proximity to the nearest WUI area are found. A regional-scale analysis shows a strong influence of the WUI zones on large fires in parts of the Mediterranean regions. Results indicate that the probability of large burned surfaces increases with diminishing WUI distance in touristic regions like Sardinia, Provence-Alpes-Côte d'Azur, or in regions with a strong peri-urban component as Catalunya, Comunidad de Madrid, Comunidad Valenciana. For the above regions, probability curves of large burned surfaces show statistical relationships (ROC value > 0.5) inside a 5000 m buffer of the nearest WUI. Wise land management can provide a valuable ecosystem service of fire risk reduction that is currently not explicitly included in ecosystem service valuations. The results re-emphasise the importance of including this ecosystem service in landscape valuations to account for the significant landscape function of reducing the risk of catastrophic large fires. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Quantitative fractography by digital image processing: NIH Image macro tools for stereo pair analysis and 3-D reconstruction.

PubMed

Hein, L R

2001-10-01

A set of NIH Image macro programs was developed to make qualitative and quantitative analyses from digital stereo pictures produced by scanning electron microscopes. These tools were designed for image alignment, anaglyph representation, animation, reconstruction of true elevation surfaces, reconstruction of elevation profiles, true-scale elevation mapping and, for the quantitative approach, surface area and roughness calculations. Limitations on time processing, scanning techniques and programming concepts are also discussed.

A high-performance dual-scale porous electrode for vanadium redox flow batteries

NASA Astrophysics Data System (ADS)

Zhou, X. L.; Zeng, Y. K.; Zhu, X. B.; Wei, L.; Zhao, T. S.

2016-09-01

In this work, we present a simple and cost-effective method to form a dual-scale porous electrode by KOH activation of the fibers of carbon papers. The large pores (∼10 μm), formed between carbon fibers, serve as the macroscopic pathways for high electrolyte flow rates, while the small pores (∼5 nm), formed on carbon fiber surfaces, act as active sites for rapid electrochemical reactions. It is shown that the Brunauer-Emmett-Teller specific surface area of the carbon paper is increased by a factor of 16 while maintaining the same hydraulic permeability as that of the original carbon paper electrode. We then apply the dual-scale electrode to a vanadium redox flow battery (VRFB) and demonstrate an energy efficiency ranging from 82% to 88% at current densities of 200-400 mA cm-2, which is record breaking as the highest performance of VRFB in the open literature.

Sauropod necks: are they really for heat loss?

PubMed

Henderson, Donald M

2013-01-01

Three-dimensional digital models of 16 different sauropods were used to examine the scaling relationship between metabolism and surface areas of the whole body, the neck, and the tail in an attempt to see if the necks could have functioned as radiators for the elimination of excess body heat. The sauropod taxa sample ranged in body mass from a 639 kg juvenile Camarasaurus to a 25 t adult Brachiosaurus. Metabolism was assumed to be directly proportional to body mass raised to the ¾ power, and estimates of body mass accounted for the presence of lungs and systems of air sacs in the trunk and neck. Surface areas were determined by decomposing the model surfaces into triangles and their areas being computed by vector methods. It was found that total body surface area was almost isometric with body mass, and that it showed negative allometry when plotted against metabolic rate. In contrast, neck area showed positive allometry when plotted against metabolic rate. Tail area show negative allometry with respect to metabolic rate. The many uncertainties about the biology of sauropods, and the variety of environmental conditions that different species experienced during the groups 150 million years of existence, make it difficult to be absolutely certain about the function of the neck as a radiator. However, the functional combination of the allometric increase of neck area, the systems of air sacs in the neck and trunk, the active control of blood flow between the core and surface of the body, changing skin color, and strategic orientation of the neck with respect to wind, make it plausible that the neck could have functioned as a radiator to avoid over-heating.

Sauropod Necks: Are They Really for Heat Loss?

PubMed Central

Henderson, Donald M.

2013-01-01

Three-dimensional digital models of 16 different sauropods were used to examine the scaling relationship between metabolism and surface areas of the whole body, the neck, and the tail in an attempt to see if the necks could have functioned as radiators for the elimination of excess body heat. The sauropod taxa sample ranged in body mass from a 639 kg juvenile Camarasaurus to a 25 t adult Brachiosaurus. Metabolism was assumed to be directly proportional to body mass raised to the ¾ power, and estimates of body mass accounted for the presence of lungs and systems of air sacs in the trunk and neck. Surface areas were determined by decomposing the model surfaces into triangles and their areas being computed by vector methods. It was found that total body surface area was almost isometric with body mass, and that it showed negative allometry when plotted against metabolic rate. In contrast, neck area showed positive allometry when plotted against metabolic rate. Tail area show negative allometry with respect to metabolic rate. The many uncertainties about the biology of sauropods, and the variety of environmental conditions that different species experienced during the groups 150 million years of existence, make it difficult to be absolutely certain about the function of the neck as a radiator. However, the functional combination of the allometric increase of neck area, the systems of air sacs in the neck and trunk, the active control of blood flow between the core and surface of the body, changing skin color, and strategic orientation of the neck with respect to wind, make it plausible that the neck could have functioned as a radiator to avoid over-heating. PMID:24204747

Geometry- and Length Scale-Dependent Deformation and Recovery on Micro- and Nanopatterned Shape Memory Polymer Surfaces

PubMed Central

Lee, Wei Li; Low, Hong Yee

2016-01-01

Micro- and nanoscale surface textures, when optimally designed, present a unique approach to improve surface functionalities. Coupling surface texture with shape memory polymers may generate reversibly tuneable surface properties. A shape memory polyetherurethane is used to prepare various surface textures including 2 μm- and 200 nm-gratings, 250 nm-pillars and 200 nm-holes. The mechanical deformation via stretching and recovery of the surface texture are investigated as a function of length scales and shapes. Results show the 200 nm-grating exhibiting more deformation than 2 μm-grating. Grating imparts anisotropic and surface area-to-volume effects, causing different degree of deformation between gratings and pillars under the same applied macroscopic strain. Full distribution of stress within the film causes the holes to deform more substantially than the pillars. In the recovery study, unlike a nearly complete recovery for the gratings after 10 transformation cycles, the high contribution of surface energy impedes the recovery of holes and pillars. The surface textures are shown to perform a switchable wetting function. This study provides insights into how geometric features of shape memory surface patterns can be designed to modulate the shape programming and recovery, and how the control of reversibly deformable surface textures can be applied to transfer microdroplets. PMID:27026290

Pollution distribution of heavy metals in surface soil at an informal electronic-waste recycling site.

PubMed

Fujimori, Takashi; Takigami, Hidetaka

2014-02-01

We studied distribution of heavy metals [lead (Pb), copper (Cu) and zinc (Zn)] in surface soil at an electronic-waste (e-waste) recycling workshop near Metro Manila in the Philippines to evaluate the pollution size (spot size, small area or the entire workshop), as well as to assess heavy metal transport into the surrounding soil environment. On-site length-of-stride-scale (~70 cm) measurements were performed at each surface soil point using field-portable X-ray fluorescence (FP-XRF). The surface soil at the e-waste recycling workshop was polluted with Cu, Zn and Pb, which were distributed discretely in surface soil. The site was divided into five areas based on the distance from an entrance gate (y-axis) of the e-waste recycling workshop. The three heavy metals showed similar concentration gradients in the y-axis direction. Zn, Pb and Cu concentrations were estimated to decrease to half of their maximum concentrations at ~3, 7 and 7 m from the pollution spot, respectively, inside the informal e-waste recycling workshop. Distance from an entrance may play an important role in heavy metal transport at the soil surface. Using on-site FP-XRF, we evaluated the metal ratio to characterise pollution features of the solid surface. Variability analysis of heavy metals revealed vanishing surficial autocorrelation over metre ranges. Also, the possibility of concentration prediction at unmeasured points using geostatistical kriging was evaluated, and heavy metals had a relative "small" pollution scales and remained inside the original workshop compared with toxic organohalogen compounds. Thus, exposure to heavy metals may directly influence the health of e-waste workers at the original site rather than the surrounding habitat and environmental media.

Modelling Mean Albedo of Individual Roofs in Complex Urban Areas Using Satellite Images and Airborne Laser Scanning Point Clouds

NASA Astrophysics Data System (ADS)

Kalantar, B.; Mansor, S.; Khuzaimah, Z.; Sameen, M. Ibrahim; Pradhan, B.

2017-09-01

Knowledge of surface albedo at individual roof scale is important for mitigating urban heat islands and understanding urban climate change. This study presents a method for quantifying surface albedo of individual roofs in a complex urban area using the integration of Landsat 8 and airborne LiDAR data. First, individual roofs were extracted from airborne LiDAR data and orthophotos using optimized segmentation and supervised object based image analysis (OBIA). Support vector machine (SVM) was used as a classifier in OBIA process for extracting individual roofs. The user-defined parameters required in SVM classifier were selected using v-fold cross validation method. After that, surface albedo was calculated for each individual roof from Landsat images. Finally, thematic maps of mean surface albedo of individual roofs were generated in GIS and the results were discussed. Results showed that the study area is covered by 35% of buildings varying in roofing material types and conditions. The calculated surface albedo of buildings ranged from 0.16 to 0.65 in the study area. More importantly, the results indicated that the types and conditions of roofing materials significantly effect on the mean value of surface albedo. Mean albedo of new concrete, old concrete, new steel, and old steel were found to be equal to 0.38, 0.26, 0.51, and 0.44 respectively. Replacing old roofing materials with new ones should highly prioritized.

Large-scale effects on the regulation of tropical sea surface temperature

NASA Technical Reports Server (NTRS)

Hartmann, Dennis L.; Michelsen, Marc L.

1993-01-01

The dominant terms in the surface energy budget of the tropical oceans are absorption of solar radiation and evaporative cooling. If it is assumed that relative humidity in the boundary layer remains constant, evaporative cooling will increase rapidly with sea surface temperature (SST) because of the strong temperature dependence of saturation water vapor pressure. The resulting stabilization of SST provided by evaporative cooling is sufficient to overcome positive feedback contributed by the decrease of surface net longwave cooling with increasing SST. Evaporative cooling is sensitive to small changes in boundary-layer relative humidity. Large and negative shortwave cloud forcing in the regions of highest SST are supported by the moisture convergence associated with largescale circulations. In the descending portions of these circulations the shortwave cloud forcing is suppressed. When the effect of these circulations is taken into account by spatial averaging, the area-averaged cloud forcing shows no sensitivity to area-averaged SST changes associated with the 1987 warming event in the tropical Pacific. While the shortwave cloud forcing is large and important in the convective regions, the importance of its role in regulating the average temperature of the tropics and in modulating temperature gradients within the tropics is less clear. A heuristic model of SST is used to illustrate the possible role of large-scale atmospheric circulations on SST in the tropics and the coupling between SST gradients and mean tropical SST. The intensity of large-scale circulations responds sensitivity to SST gradients and affects the mean tropical SST by supplying dry air to the planetary boundary layer. Large SST gradients generate vigorous circulations that increase evaporation and reduce the mean SST.

Assessment of Irrigation Physics in a Land Surface Modeling Framework Using Non-Traditional and Human-Practice Datasets

NASA Technical Reports Server (NTRS)

Lawston, Patricia M.; Santanello, Joseph A.; Rodell, Matthew; Franz, Trenton E.

2017-01-01

Irrigation increases soil moisture, which in turn controls water and energy fluxes from the land surface to the10 planetary boundary layer and determines plant stress and productivity. Therefore, developing a realistic representation of irrigation is critical to understanding land-atmosphere interactions in agricultural areas. Irrigation parameterizations are becoming more common in land surface models and are growing in sophistication, but there is difficulty in assessing the realism of these schemes, due to limited observations (e.g., soil moisture, evapotranspiration) and scant reporting of irrigation timing and quantity. This study uses the Noah land surface model run at high resolution within NASAs Land15 Information System to assess the physics of a sprinkler irrigation simulation scheme and model sensitivity to choice of irrigation intensity and greenness fraction datasets over a small, high resolution domain in Nebraska. Differences between experiments are small at the interannual scale but become more apparent at seasonal and daily time scales. In addition, this study uses point and gridded soil moisture observations from fixed and roving Cosmic Ray Neutron Probes and co-located human practice data to evaluate the realism of irrigation amounts and soil moisture impacts simulated by the model. Results20 show that field-scale heterogeneity resulting from the individual actions of farmers is not captured by the model and the amount of irrigation applied by the model exceeds that applied at the two irrigated fields. However, the seasonal timing of irrigation and soil moisture contrasts between irrigated and non-irrigated areas are simulated well by the model. Overall, the results underscore the necessity of both high-quality meteorological forcing data and proper representation of irrigation foraccurate simulation of water and energy states and fluxes over cropland.

Spatial Representativeness of Surface-Measured Variations of Downward Solar Radiation

NASA Astrophysics Data System (ADS)

Schwarz, M.; Folini, D.; Hakuba, M. Z.; Wild, M.

2017-12-01

When using time series of ground-based surface solar radiation (SSR) measurements in combination with gridded data, the spatial and temporal representativeness of the point observations must be considered. We use SSR data from surface observations and high-resolution (0.05°) satellite-derived data to infer the spatiotemporal representativeness of observations for monthly and longer time scales in Europe. The correlation analysis shows that the squared correlation coefficients (R2) between SSR times series decrease linearly with increasing distance between the surface observations. For deseasonalized monthly mean time series, R2 ranges from 0.85 for distances up to 25 km between the stations to 0.25 at distances of 500 km. A decorrelation length (i.e., the e-folding distance of R2) on the order of 400 km (with spread of 100-600 km) was found. R2 from correlations between point observations and colocated grid box area means determined from satellite data were found to be 0.80 for a 1° grid. To quantify the error which arises when using a point observation as a surrogate for the area mean SSR of larger surroundings, we calculated a spatial sampling error (SSE) for a 1° grid of 8 (3) W/m2 for monthly (annual) time series. The SSE based on a 1° grid, therefore, is of the same magnitude as the measurement uncertainty. The analysis generally reveals that monthly mean (or longer temporally aggregated) point observations of SSR capture the larger-scale variability well. This finding shows that comparing time series of SSR measurements with gridded data is feasible for those time scales.

Clay mineral continental amplifier for marine carbon sequestration in a greenhouse ocean

PubMed Central

Kennedy, Martin J.; Wagner, Thomas

2011-01-01

The majority of carbon sequestration at the Earth’s surface occurs in marine continental margin settings within fine-grained sediments whose mineral properties are a function of continental climatic conditions. We report very high mineral surface area (MSA) values of 300 and 570 m2 g in Late Cretaceous black shales from Ocean Drilling Program site 959 of the Deep Ivorian Basin that vary on subcentennial time scales corresponding with abrupt increases from approximately 3 to approximately 18% total organic carbon (TOC). The observed MSA changes with TOC across multiple scales of variability and on a sample-by-sample basis (centimeter scale), provides a rigorous test of a hypothesized influence on organic carbon burial by detrital clay mineral controlled MSA. Changes in TOC also correspond with geochemical and sedimentological evidence for water column anoxia. Bioturbated intervals show a lower organic carbon loading on mineral surface area of 0.1 mg-OC m-2 when compared to 0.4 mg-OC m-2 for laminated and sulfidic sediments. Although either anoxia or mineral surface protection may be capable of producing TOC of < 5%, when brought together they produced the very high TOC (10–18%) apparent in these sediments. This nonlinear response in carbon burial resulted from minor precession-driven changes of continental climate influencing clay mineral properties and runoff from the African continent. This study identifies a previously unrecognized land–sea connection among continental weathering, clay mineral production, and anoxia and a nonlinear effect on marine carbon sequestration during the Coniacian-Santonian Oceanic Anoxic Event 3 in the tropical eastern Atlantic. PMID:21576498

Clear microstructure-performance relationships in Mn-containing perovskite and hexaaluminate compounds prepared by activated reactive synthesis.

PubMed

Laassiri, Said; Bion, Nicolas; Duprez, Daniel; Royer, Sébastien; Alamdari, Houshang

2014-03-07

Microstructural properties of mixed oxides play essential roles in their oxygen mobility and consequently in their catalytic performances. Two families of mixed oxides (perovskite and hexaaluminate) with different microstructural features, such as crystal size and specific surface area, were prepared using the activated reactive synthesis (ARS) method. It was shown that ARS is a flexible route to synthesize both mixed oxides with nano-scale crystal size and high specific surface area. Redox properties and oxygen mobility were found to be strongly affected by the material microstructure. Catalytic activities of hexaaluminate and perovskite materials for methane oxidation were discussed in the light of structural, redox and oxygen mobility properties.

Scale-up considerations for surface collecting agent assisted in-situ burn crude oil spill response experiments in the Arctic: Laboratory to field-scale investigations.

PubMed

Bullock, Robin J; Aggarwal, Srijan; Perkins, Robert A; Schnabel, William

2017-04-01

In the event of a marine oil spill in the Arctic, government agencies, industry, and the public have a stake in the successful implementation of oil spill response. Because large spills are rare events, oil spill response techniques are often evaluated with laboratory and meso-scale experiments. The experiments must yield scalable information sufficient to understand the operability and effectiveness of a response technique under actual field conditions. Since in-situ burning augmented with surface collecting agents ("herders") is one of the few viable response options in ice infested waters, a series of oil spill response experiments were conducted in Fairbanks, Alaska, in 2014 and 2015 to evaluate the use of herders to assist in-situ burning and the role of experimental scale. This study compares burn efficiency and herder application for three experimental designs for in-situ burning of Alaska North Slope crude oil in cold, fresh waters with ∼10% ice cover. The experiments were conducted in three project-specific constructed venues with varying scales (surface areas of approximately 0.09 square meters, 9 square meters and 8100 square meters). The results from the herder assisted in-situ burn experiments performed at these three different scales showed good experimental scale correlation and no negative impact due to the presence of ice cover on burn efficiency. Experimental conclusions are predominantly associated with application of the herder material and usability for a given experiment scale to make response decisions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Map showing selected surface-water data for the Alton-Kolob coal-fields area, Utah

USGS Publications Warehouse

Price, Don

1982-01-01

This is one of a series of maps that describe the geology and related natural resources of the Alton-Kolob coal-fields area, Utah. Streamflow records used to compile the map and the following table were collected by the U.S. Geological Survey in cooperation with the Utah Department of Natural Resources, Division of Water Rights, and the Utah Department of Transportation. The principal runoff-producing areas were delineated form a work map (scale 1:250,000) compiled to estimate water yields in Utah (Bagley and others, 1964).

Effects of vegetation heterogeneity and surface topography on spatial scaling of net primary productivity

NASA Astrophysics Data System (ADS)

Chen, J. M.; Chen, X.; Ju, W.

2013-03-01

Due to the heterogeneous nature of the land surface, spatial scaling is an inevitable issue in the development of land models coupled with low-resolution Earth system models (ESMs) for predicting land-atmosphere interactions and carbon-climate feedbacks. In this study, a simple spatial scaling algorithm is developed to correct errors in net primary productivity (NPP) estimates made at a coarse spatial resolution based on sub-pixel information of vegetation heterogeneity and surface topography. An eco-hydrological model BEPS-TerrainLab, which considers both vegetation and topographical effects on the vertical and lateral water flows and the carbon cycle, is used to simulate NPP at 30 m and 1 km resolutions for a 5700 km2 watershed with an elevation range from 518 m to 3767 m in the Qinling Mountain, Shaanxi Province, China. Assuming that the NPP simulated at 30 m resolution represents the reality and that at 1 km resolution is subject to errors due to sub-pixel heterogeneity, a spatial scaling index (SSI) is developed to correct the coarse resolution NPP values pixel by pixel. The agreement between the NPP values at these two resolutions is improved considerably from R2 = 0.782 to R2 = 0.884 after the correction. The mean bias error (MBE) in NPP modeled at the 1 km resolution is reduced from 14.8 g C m-2 yr-1 to 4.8 g C m-2 yr-1 in comparison with NPP modeled at 30 m resolution, where the mean NPP is 668 g C m-2 yr-1. The range of spatial variations of NPP at 30 m resolution is larger than that at 1 km resolution. Land cover fraction is the most important vegetation factor to be considered in NPP spatial scaling, and slope is the most important topographical factor for NPP spatial scaling especially in mountainous areas, because of its influence on the lateral water redistribution, affecting water table, soil moisture and plant growth. Other factors including leaf area index (LAI), elevation and aspect have small and additive effects on improving the spatial scaling between these two resolutions.

Effects of vegetation heterogeneity and surface topography on spatial scaling of net primary productivity

NASA Astrophysics Data System (ADS)

Chen, J. M.; Chen, X.; Ju, W.

2013-07-01

Due to the heterogeneous nature of the land surface, spatial scaling is an inevitable issue in the development of land models coupled with low-resolution Earth system models (ESMs) for predicting land-atmosphere interactions and carbon-climate feedbacks. In this study, a simple spatial scaling algorithm is developed to correct errors in net primary productivity (NPP) estimates made at a coarse spatial resolution based on sub-pixel information of vegetation heterogeneity and surface topography. An eco-hydrological model BEPS-TerrainLab, which considers both vegetation and topographical effects on the vertical and lateral water flows and the carbon cycle, is used to simulate NPP at 30 m and 1 km resolutions for a 5700 km2 watershed with an elevation range from 518 m to 3767 m in the Qinling Mountain, Shanxi Province, China. Assuming that the NPP simulated at 30 m resolution represents the reality and that at 1 km resolution is subject to errors due to sub-pixel heterogeneity, a spatial scaling index (SSI) is developed to correct the coarse resolution NPP values pixel by pixel. The agreement between the NPP values at these two resolutions is improved considerably from R2 = 0.782 to R2 = 0.884 after the correction. The mean bias error (MBE) in NPP modelled at the 1 km resolution is reduced from 14.8 g C m-2 yr-1 to 4.8 g C m-2 yr-1 in comparison with NPP modelled at 30 m resolution, where the mean NPP is 668 g C m-2 yr-1. The range of spatial variations of NPP at 30 m resolution is larger than that at 1 km resolution. Land cover fraction is the most important vegetation factor to be considered in NPP spatial scaling, and slope is the most important topographical factor for NPP spatial scaling especially in mountainous areas, because of its influence on the lateral water redistribution, affecting water table, soil moisture and plant growth. Other factors including leaf area index (LAI) and elevation have small and additive effects on improving the spatial scaling between these two resolutions.

Oil Slick Observation at Low Incidence Angles in Ku-Band

NASA Astrophysics Data System (ADS)

Panfilova, M. A.; Karaev, V. Y.; Guo, Jie

2018-03-01

On the 20 April 2010 the oil platform Deep Water Horizon in the Gulf of Mexico suffered an explosion during the final phases of drilling an exploratory well. As a result, an oil film covered the sea surface area of several thousand square kilometers. In the present paper the data of the Ku-band Precipitation Radar, which operates at low incidence angles, were used to explore the oil spill event. The two-scale model of the scattering surface was used to describe radar backscatter from the sea surface. The algorithm for retrieval of normalized radar cross section at nadir and the total slope variance of large-scale waves compared to the wavelength of electromagnetic wave (22 mm) was developed for the Precipitation Radar swath. It is shown that measurements at low incidence angles can be used for oil spill detection. This is the first time that the dependence of mean square slope of large-scale waves on wind speed has been obtained for oil slicks from Ku-band data, and compared to mean square slope obtained by Cox and Munk from optical data.

Point contact tunneling spectroscopy apparatus for large scale mapping of surface superconducting properties

DOE PAGES

Groll, Nickolas; Pellin, Michael J.; Zasadzinksi, John F.; ...

2015-09-18

In this paper, we describe the design and testing of a point contact tunneling spectroscopy device that can measure material surface superconducting properties (i.e., the superconducting gap Δ and the critical temperature T C) and density of states over large surface areas with size up to mm 2. The tip lateral (X,Y) motion, mounted on a (X,Y,Z) piezo-stage, was calibrated on a patterned substrate consisting of Nb lines sputtered on a gold film using both normal (Al) and superconducting (PbSn) tips at 1.5 K. The tip vertical (Z) motion control enables some adjustment of the tip-sample junction resistance that canmore » be measured over 7 orders of magnitudes from a quasi-ohmic regime (few hundred Ω) to the tunnel regime (from tens of kΩ up to few GΩ). The low noise electronic and LabVIEW program interface are also presented. Finally, the point contact regime and the large-scale motion capabilities are of particular interest for mapping and testing the superconducting properties of macroscopic scale superconductor-based devices.« less

Global deformation on the surface of Venus

NASA Technical Reports Server (NTRS)

Bilotti, Frank; Connors, Chris; Suppe, John

1992-01-01

Large-scale mapping of tectonic structures on Venus shows that there is an organized global distribution to deformation. The structures we emphasize are linear compressive mountain belts, extensional rafted zones, and the small-scale but widely distributed wrinkle ridges. Ninety percent of the area of the planet's compressive mountain belts are concentrated in the northern hemisphere whereas the southern hemisphere is dominated by extension and small-scale compression. We propose that this striking concentration of fold belts in the northern hemisphere, along with the globe-encircling equatorial rift system, represents a global organization to deformation on Venus.

A simple method for estimating the size of nuclei on fractal surfaces

NASA Astrophysics Data System (ADS)

Zeng, Qiang

2017-10-01

Determining the size of nuclei on complex surfaces remains a big challenge in aspects of biological, material and chemical engineering. Here the author reported a simple method to estimate the size of the nuclei in contact with complex (fractal) surfaces. The established approach was based on the assumptions of contact area proportionality for determining nucleation density and the scaling congruence between nuclei and surfaces for identifying contact regimes. It showed three different regimes governing the equations for estimating the nucleation site density. Nuclei in the size large enough could eliminate the effect of fractal structure. Nuclei in the size small enough could lead to the independence of nucleation site density on fractal parameters. Only when nuclei match the fractal scales, the nucleation site density is associated with the fractal parameters and the size of the nuclei in a coupling pattern. The method was validated by the experimental data reported in the literature. The method may provide an effective way to estimate the size of nuclei on fractal surfaces, through which a number of promising applications in relative fields can be envisioned.

Networks of triboelectric nanogenerators for harvesting water wave energy: a potential approach toward blue energy.

PubMed

Chen, Jun; Yang, Jin; Li, Zhaoling; Fan, Xing; Zi, Yunlong; Jing, Qingshen; Guo, Hengyu; Wen, Zhen; Pradel, Ken C; Niu, Simiao; Wang, Zhong Lin

2015-03-24

With 70% of the earth's surface covered with water, wave energy is abundant and has the potential to be one of the most environmentally benign forms of electric energy. However, owing to lack of effective technology, water wave energy harvesting is almost unexplored as an energy source. Here, we report a network design made of triboelectric nanogenerators (TENGs) for large-scale harvesting of kinetic water energy. Relying on surface charging effect between the conventional polymers and very thin layer of metal as electrodes for each TENG, the TENG networks (TENG-NW) that naturally float on the water surface convert the slow, random, and high-force oscillatory wave energy into electricity. On the basis of the measured output of a single TENG, the TENG-NW is expected to give an average power output of 1.15 MW from 1 km(2) surface area. Given the compelling features, such as being lightweight, extremely cost-effective, environmentally friendly, easily implemented, and capable of floating on the water surface, the TENG-NW renders an innovative and effective approach toward large-scale blue energy harvesting from the ocean.

A comprehensive review of milk fouling on heated surfaces.

PubMed

Sadeghinezhad, E; Kazi, S N; Dahari, M; Safaei, Mohammad Reza; Sadri, Rad; Badarudin, A

2015-01-01

Heat exchanger performance degrades rapidly during operation due to formation of deposits on heat transfer surfaces which ultimately reduces service life of the equipment. Due to scaling, product deteriorates which causes lack of proper heating. Chemistry of milk scaling is qualitatively understood and the mathematical models for fouling at low temperatures have been produced but the behavior of systems at ultra high temperature processing has to be studied further to understand in depth. In diversified field, the effect of whey protein fouling along with pressure drop in heat exchangers were conducted by many researchers. Adding additives, treatment of heat exchanger surfaces and changing of heat exchanger configurations are notable areas of investigation in milk fouling. The present review highlighted information about previous work on fouling, influencing parameters of fouling and its mitigation approach and ends up with recommendations for retardation of milk fouling and necessary measures to perform the task.

Multiscale deformation behavior for multilayered steel by in-situ FE-SEM

NASA Astrophysics Data System (ADS)

Tanaka, Y.; Kishimoto, S.; Yin, F.; Kobayashi, M.; Tomimatsu, T.; Kagawa, K.

2010-03-01

The multi-scale deformation behavior of multi-layered steel during tensile loading was investigated by in-situ FE-SEM observation coupled with multi-scale pattern. The material used was multi-layered steel sheet consisting of martensitic and austenitic stainless steel layers. Prior to in-situ tensile testing, the multi-scale pattern combined with a grid and random dots were fabricated by electron beam lithography on the polished surface in the area of 1 mm2 to facilitate direct observation of multi-scale deformation. Both of the grids with pitches of 10 μm and a random speckle pattern ranging from 200 nm to a few μm sizes were drawn onto the specimen surface at same location. The electron moiré method was applied to measure the strain distribution in the deformed specimens at a millimeter scale and digital images correlation method was applied to measure the in-plane deformation and strain distribution at a micron meter scale acquired before and after at various increments of straining. The results showed that the plastic deformation in the austenitic stainless steel layer was larger than the martensitic steel layer at millimeter scale. However, heterogeneous intrinsic grain-scale plastic deformation was clearly observed and it increased with increasing the plastic deformation.

A model for allometric scaling of mammalian metabolism with ambient heat loss.

PubMed

Kwak, Ho Sang; Im, Hong G; Shim, Eun Bo

2016-03-01

Allometric scaling, which represents the dependence of biological traits or processes on body size, is a long-standing subject in biological science. However, there has been no study to consider heat loss to the ambient and an insulation layer representing mammalian skin and fur for the derivation of the scaling law of metabolism. A simple heat transfer model is proposed to analyze the allometry of mammalian metabolism. The present model extends existing studies by incorporating various external heat transfer parameters and additional insulation layers. The model equations were solved numerically and by an analytic heat balance approach. A general observation is that the present heat transfer model predicted the 2/3 surface scaling law, which is primarily attributed to the dependence of the surface area on the body mass. External heat transfer effects introduced deviations in the scaling law, mainly due to natural convection heat transfer, which becomes more prominent at smaller mass. These deviations resulted in a slight modification of the scaling exponent to a value < 2/3. The finding that additional radiative heat loss and the consideration of an outer insulation fur layer attenuate these deviation effects and render the scaling law closer to 2/3 provides in silico evidence for a functional impact of heat transfer mode on the allometric scaling law in mammalian metabolism.

Scaling trace organic contaminant adsorption capacity by granular activated carbon.

PubMed

Corwin, Christopher J; Summers, R Scott

2010-07-15

The role of particle size on the reduction of granular activated carbon (GAC) adsorption capacity for trace organic contaminants by dissolved organic matter (DOM) is examined and applied to performance scale-up. The adsorption capacity reduction, termed fouling, must be scalable in order to use bench scale tests, such as the rapid small-scale column test (RSSCT) to predict full-scale breakthrough. Equilibrium adsorption capacity tests with GAC preloaded with DOM and RSSCT breakthrough curves at three different GAC particle sizes indicate that GAC adsorption capacity is dependent on GAC particle size when DOM is present. Thus, the RSSCT cannot be expected to match full-scale results regardless of which RSSCT design approach is used (constant or proportional diffusivity), unless a scaling factor is applied to the results. Proportional diffusivity RSSCT breakthrough curves demonstrate that surface concentration of DOM is not a good measure of fouling. It is hypothesized that pore blockage is the mechanism responsible for the dependence on particle size. As GAC particle size increases, the microporous surface area behind a constricted pore also increases. The result is lower adsorption capacity per mass of adsorbent in the larger GAC particles. A scaling methodology for equilibrium and breakthrough data is presented that accounts for the dependence of NOM preloading effects on GAC particle diameter.

Quantitative analysis of surface characteristics and morphology in Death Valley, California using AIRSAR data

NASA Technical Reports Server (NTRS)

Kierein-Young, K. S.; Kruse, F. A.; Lefkoff, A. B.

1992-01-01

The Jet Propulsion Laboratory Airborne Synthetic Aperture Radar (JPL-AIRSAR) is used to collect full polarimetric measurements at P-, L-, and C-bands. These data are analyzed using the radar analysis and visualization environment (RAVEN). The AIRSAR data are calibrated using in-scene corner reflectors to allow for quantitative analysis of the radar backscatter. RAVEN is used to extract surface characteristics. Inversion models are used to calculate quantitative surface roughness values and fractal dimensions. These values are used to generate synthetic surface plots that represent the small-scale surface structure of areas in Death Valley. These procedures are applied to a playa, smooth salt-pan, and alluvial fan surfaces in Death Valley. Field measurements of surface roughness are used to verify the accuracy.

Effects of spatial resolution and landscape structure on land cover characterization

NASA Astrophysics Data System (ADS)

Yang, Wenli

This dissertation addressed problems in scaling, problems that are among the main challenges in remote sensing. The principal objective of the research was to investigate the effects of changing spatial scale on the representation of land cover. A second objective was to determine the relationship between such effects, characteristics of landscape structure and scaling procedures. Four research issues related to spatial scaling were examined. They included: (1) the upscaling of Normalized Difference Vegetation Index (NDVI); (2) the effects of spatial scale on indices of landscape structure; (3) the representation of land cover databases at different spatial scales; and (4) the relationships between landscape indices and land cover area estimations. The overall bias resulting from non-linearity of NDVI in relation to spatial resolution is generally insignificant as compared to other factors such as influences of aerosols and water vapor. The bias is, however, related to land surface characteristics. Significant errors may be introduced in heterogeneous areas where different land cover types exhibit strong spectral contrast. Spatially upscaled SPOT and TM NDVIs have information content comparable with the AVHRR-derived NDVI. Indices of landscape structure and spatial resolution are generally related, but the exact forms of the relationships are subject to changes in other factors including the basic patch unit constituting a landscape and the proportional area of foreground land cover under consideration. The extent of agreement between spatially aggregated coarse resolution land cover datasets and full resolution datasets changes with the properties of the original datasets, including the pixel size and class definition. There are close relationships between landscape structure and class areas estimated from spatially aggregated land cover databases. The relationships, however, do not permit extension from one area to another. Inversion calibration across different geographic/ecological areas is, therefore, not feasible. Different rules govern the land cover area changes across resolutions when different upscaling methods are used. Special attention should be given to comparison between land cover maps derived using different methods.

Multiscale roughness characterization from multiresolution remote sensing data acquired over the Asal-Ghoubbet rift, Republic of Djibouti

NASA Astrophysics Data System (ADS)

Labarre, Sébastien; Jacquemoud, Stéphane; Ferrari, Cécile; Delorme, Arthur; Rupnik, Ewelina; Derrien, Allan; Pierrot-Deseilligny, Marc; Grandin, Raphaël; Jalludin, Mohamed

2017-04-01

Surface roughness is a key parameter in soil physics which controls many surface processes at a wide range of scales: microscopic and mesoscopic scales from 10 μm to 1 cm (soil particles or regolith), macroscopic scale from 1 cm to 1 m (clods, aggregates of rock or ice, micro-fractures or lava flows), and topographic scale from 1 m to several kilometers (faults, hills, craters or mountains). While it is recognized that surface roughness is strongly scale-dependent, it is often expressed as an integrated parameter (root-mean-square height, correlation length, tortuosity index), which does not address the full range of spatial features present on the surface. In particular, the Hapke roughness parameter is defined as the mean slope angle of the facets composing the surface, integrated over all scales from the microscopic to the macroscopic scales. Yet its physical meaning is still a question at issue, as the scale at which it occurs is undefined in the model. Photogrammetry has been shown to be an inexpensive and powerful method for topography reconstruction from optical data. We took advantage of a series of 21 Pléiades-1B images (video acquisition mode) to build a global digital elevation model (DEM) over the Asal-Ghoubbet rift, Republic of Djibouti. Additionally, we acquired close range data with a quadcopter equipped with a HD camera. Topography at four scales is available: 1 m with the satellite images (694 km), 1 cm with the drone flying at medium altitude ( 100 m), 1 mm with the drone flying at low altitude ( 10 m), and <1 mm with the handheld camera ( 1.5 m). We have defined twenty-two sites, 20 × 30 m in dimension, corresponding to a wide range of volcanic and sedimentary terrains, from regolith-like structures to very rough lava flows, over which DEMs have been generated at two or more resolutions. In order to investigate the contribution of each scale to the integrated roughness and to test the ability of the Hapke model to retrieve a roughness parameter that depicts well the ground truth, we applied two multiscale methods: fractal analysis and wavelet transform. The latter allows splitting the frequency band of a signal in several sub-bands, each of which corresponding to a spatial scale. By analyzing data acquired at Piton de la Fournaise Volcano, Réunion island, we showed that wavelet transform is a very powerful tool for characterizing roughness regimes over scales and that sub-centimeter surface features mostly explain the integrated roughness for meter-sized surfaces (Labarre et al., 2017, Icarus). This has to be confirmed on Djibouti terrains, for which we have a broader range of resolutions and larger areas.

High surface area calcite

NASA Astrophysics Data System (ADS)

Schultz, L. N.; Andersson, M. P.; Dalby, K. N.; Müter, D.; Okhrimenko, D. V.; Fordsmand, H.; Stipp, S. L. S.

2013-05-01

Calcite (CaCO3) is important in many fields—in nature, because it is a component of aquifers, oil reservoirs and prospective CO2 storage sites, and in industry, where it is used in products as diverse as paper, toothpaste, paint, plastic and aspirin. It is difficult to obtain high purity calcite with a high surface area but such material is necessary for industrial applications and for fundamental calcite research. Commercial powder is nearly always contaminated with growth inhibitors such as sugars, citrate or pectin and most laboratory synthesis methods deliver large precipitates, often containing vaterite or aragonite. To address this problem, we (i) adapted the method of carbonating a Ca(OH)2 slurry with CO2 gas to develop the first simple, cheap, safe and reproducible procedure using common laboratory equipment, to obtain calcite that reproducibly had a surface area of 14-17 m2/g and (ii) conducted a thorough characterization of the product. Scanning electron microscopy (SEM) revealed nanometer scale, rhombohedral crystals. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR) confirmed highly crystalline, pure calcite that more closely resembles the dimensions of the biogenic calcite produced by algae in coccoliths than other methods for synthesizing calcite. We suggest that this calcite is useful when purity and high surface area are important.

Sensitivity Analysis of SWAT Nitrogen Simulations with and without In-Stream Processes

EPA Science Inventory

Nitrogen (N) losses to surface waters are of great concern on both national and regional scales. Scientists have concluded that large areas of hypoxia in the northern Gulf of Mexico are due to excessive nutrients derived primarily from agricultural runoff via the Mississippi Rive...

IMPEDIMENTS AND SOLUTIONS TO SUSTAINABLE, WATERSHED-SCALE URBAN STORMWATER MANAGEMENT: LESSONS FROM AUSTRALIA AND THE UNITED STATES

EPA Science Inventory

In urban and exurban areas, stormwater runoff is a primary stressor on surface waters (streams, wetlands, lakes, estuaries, and coastal waters). Conventional urban stormwater drainage systems often route runoff directly to streams and rivers, thus exacerbating pollutant inputs a...

A small-scale, rolled-membrane microfluidic artificial lung designed towards future large area manufacturing.

PubMed

Thompson, A J; Marks, L H; Goudie, M J; Rojas-Pena, A; Handa, H; Potkay, J A

2017-03-01

Artificial lungs have been used in the clinic for multiple decades to supplement patient pulmonary function. Recently, small-scale microfluidic artificial lungs (μAL) have been demonstrated with large surface area to blood volume ratios, biomimetic blood flow paths, and pressure drops compatible with pumpless operation. Initial small-scale microfluidic devices with blood flow rates in the μ l/min to ml/min range have exhibited excellent gas transfer efficiencies; however, current manufacturing techniques may not be suitable for scaling up to human applications. Here, we present a new manufacturing technology for a microfluidic artificial lung in which the structure is assembled via a continuous "rolling" and bonding procedure from a single, patterned layer of polydimethyl siloxane (PDMS). This method is demonstrated in a small-scale four-layer device, but is expected to easily scale to larger area devices. The presented devices have a biomimetic branching blood flow network, 10  μ m tall artificial capillaries, and a 66  μ m thick gas transfer membrane. Gas transfer efficiency in blood was evaluated over a range of blood flow rates (0.1-1.25 ml/min) for two different sweep gases (pure O 2 , atmospheric air). The achieved gas transfer data closely follow predicted theoretical values for oxygenation and CO 2 removal, while pressure drop is marginally higher than predicted. This work is the first step in developing a scalable method for creating large area microfluidic artificial lungs. Although designed for microfluidic artificial lungs, the presented technique is expected to result in the first manufacturing method capable of simply and easily creating large area microfluidic devices from PDMS.

Regulating Force in Putting by Using the Borg CR100 scale(®).

PubMed

Molander, Bo; Olsson, C-J; Stenling, Andreas; Borg, Elisabet

2013-01-01

Studies investigating the regulation of force of motor actions are scarce, and particularly so in the area of sports. This is surprising, considering that in most sports precise force is of great importance. The current study demonstrates how a psychophysical scale, the Borg CR100 scale(®) (Borg and Borg, 2001), can be used to assess subjective force as well as regulate force in putting. Psychophysical functions were calculated on the relationships between judgments of force using the CR100 scale and the length of putting shots, examined in a laboratory setting, where 44 amateur golfers played on both flat and uphill surfaces. High agreement and consistency between CR 100 ratings and distances putted was demonstrated. No significant differences in handling the scale were observed between younger (mean age ≈37 years) and older (mean age ≈69 years) players or between players of different skill level. This study provides a new innovative use of an existing instrument, the Borg CR 100 scale(®), in order to understand the regulation of force needed for putts of various lengths and surfaces. These results and the potential future benefits of the psychophysical approach in golf are discussed.

Spatial Modeling and Uncertainty Assessment of Fine Scale Surface Processes Based on Coarse Terrain Elevation Data

NASA Astrophysics Data System (ADS)

Rasera, L. G.; Mariethoz, G.; Lane, S. N.

2017-12-01

Frequent acquisition of high-resolution digital elevation models (HR-DEMs) over large areas is expensive and difficult. Satellite-derived low-resolution digital elevation models (LR-DEMs) provide extensive coverage of Earth's surface but at coarser spatial and temporal resolutions. Although useful for large scale problems, LR-DEMs are not suitable for modeling hydrologic and geomorphic processes at scales smaller than their spatial resolution. In this work, we present a multiple-point geostatistical approach for downscaling a target LR-DEM based on available high-resolution training data and recurrent high-resolution remote sensing images. The method aims at generating several equiprobable HR-DEMs conditioned to a given target LR-DEM by borrowing small scale topographic patterns from an analogue containing data at both coarse and fine scales. An application of the methodology is demonstrated by using an ensemble of simulated HR-DEMs as input to a flow-routing algorithm. The proposed framework enables a probabilistic assessment of the spatial structures generated by natural phenomena operating at scales finer than the available terrain elevation measurements. A case study in the Swiss Alps is provided to illustrate the methodology.

A DNS study of the physical mechanisms associated with density ratio influence on turbulent burning velocity in premixed flames

NASA Astrophysics Data System (ADS)

Lipatnikov, Andrei N.; Chomiak, Jerzy; Sabelnikov, Vladimir A.; Nishiki, Shinnosuke; Hasegawa, Tatsuya

2018-01-01

Data obtained in 3D direct numerical simulations of statistically planar, 1D weakly turbulent flames characterised by different density ratios σ are analysed to study the influence of thermal expansion on flame surface area and burning rate. Results show that, on the one hand, the pressure gradient induced within a flame brush owing to heat release in flamelets significantly accelerates the unburned gas that deeply intrudes into the combustion products in the form of an unburned mixture finger, thus causing large-scale oscillations of the burning rate and flame brush thickness. Under the conditions of the present simulations, the contribution of this mechanism to the creation of the flame surface area is substantial and is increased by σ, thus implying an increase in the burning rate by σ. On the other hand, the total flame surface areas simulated at σ = 7.53 and 2.5 are approximately equal. The apparent inconsistency between these results implies the existence of another thermal expansion effect that reduces the influence of σ on the flame surface area and burning rate. Investigation of the issue shows that the flow acceleration by the combustion-induced pressure gradient not only creates the flame surface area by pushing the finger tip into the products, but also mitigates wrinkling of the flame surface (the side surface of the finger) by turbulent eddies. The latter effect is attributed to the high-speed (at σ = 7.53) axial flow of the unburned gas, which is induced by the axial pressure gradient within the flame brush (and the finger). This axial flow acceleration reduces the residence time of a turbulent eddy in an unburned zone of the flame brush (e.g. within the finger). Therefore, the capability of the eddy for wrinkling the flamelet surface (e.g. the side finger surface) is weakened owing to a shorter residence time.

Impact of Water Withdrawals from Groundwater and Surface Water on Continental Water Storage Variations

NASA Technical Reports Server (NTRS)

Doell, Petra; Hoffmann-Dobrev, Heike; Portmann, Felix T.; Siebert, Stefan; Eicker, Annette; Rodell, Matthew; Strassberg, Gil

2011-01-01

Humans have strongly impacted the global water cycle, not only water flows but also water storage. We have performed a first global-scale analysis of the impact of water withdrawals on water storage variations, using the global water resources and use model WaterGAP. This required estimation of fractions of total water withdrawals from groundwater, considering five water use sectors. According to our assessment, the source of 35% of the water withdrawn worldwide (4300 cubic km/yr during 1998-2002) is groundwater. Groundwater contributes 42%, 36% and 27% of water used for irrigation, households and manufacturing, respectively, while we assume that only surface water is used for livestock and for cooling of thermal power plants. Consumptive water use was 1400 cubic km/yr during 1998-2002. It is the sum of the net abstraction of 250 cubic km/yr of groundwater (taking into account evapotranspiration and return flows of withdrawn surface water and groundwater) and the net abstraction of 1150 km3/yr of surface water. Computed net abstractions indicate, for the first time at the global scale, where and when human water withdrawals decrease or increase groundwater or surface water storage. In regions with extensive surface water irrigation, such as Southern China, net abstractions from groundwater are negative, i.e. groundwater is recharged by irrigation. The opposite is true for areas dominated by groundwater irrigation, such as in the High Plains aquifer of the central USA, where net abstraction of surface water is negative because return flow of withdrawn groundwater recharges the surface water compartments. In intensively irrigated areas, the amplitude of seasonal total water storage variations is generally increased due to human water use; however, in some areas, it is decreased. For the High Plains aquifer and the whole Mississippi basin, modeled groundwater and total water storage variations were compared with estimates of groundwater storage variations based on groundwater table observations, and with estimates of total water storage variations from the GRACE satellites mission. Due to the difficulty in estimating area-averaged seasonal groundwater storage variations from point observations of groundwater levels, it is uncertain whether WaterGAP underestimates actual variations or not. We conclude that WaterGAP possibly overestimates water withdrawals in the High Plains aquifer where impact of human water use on water storage is readily discernible based on WaterGAP calculations and groundwater observations. No final conclusion can be drawn regarding the possibility of monitoring water withdrawals in the High Plains aquifer using GRACE. For the less intensively irrigated Mississippi basin, observed and modeled seasonal groundwater storage reveals a discernible impact of water withdrawals in the basin, but this is not the case for total water storage such that water withdrawals at the scale of the whole Mississippi basin cannot be monitored by GRACE.

Production of large-scale, freestanding vanadium pentoxide nanobelt porous structures

NASA Astrophysics Data System (ADS)

Yun, Yong Ju; Kim, Byung Hoon; Hong, Won G.; Kim, Chang Hee; Kim, Yark Yeon; Jeong, Eun-Ju; Jang, Won Ick; Yu, Han Young

2012-02-01

Large-scale, freestanding, porous structures of vanadium pentoxide nanobelts (VPNs) were successfully prepared using the template-free freeze-drying method. The porous and multi-layered VPN macrostructures are composed of randomly oriented long nanobelts (over 100 μm) and their side length can be controlled up to a few tens of centimetres. Also, the bulk density and surface area of these macrostructures are 3-5 mg cm-3 and 40-80 m2 g-1, respectively, which are similar to those of the excellent adsorbents. In addition, the removal efficiency measurements of ammonia molecules revealed that the VPN porous structures can adsorb the ammonia molecules with the combinations of van der Waals forces and strong chemical bonding by functional groups on the VPN surface.

Production of large-scale, freestanding vanadium pentoxide nanobelt porous structures.

PubMed

Yun, Yong Ju; Kim, Byung Hoon; Hong, Won G; Kim, Chang Hee; Kim, Yark Yeon; Jeong, Eun-ju; Jang, Won Ick; Yu, Han Young

2012-03-07

Large-scale, freestanding, porous structures of vanadium pentoxide nanobelts (VPNs) were successfully prepared using the template-free freeze-drying method. The porous and multi-layered VPN macrostructures are composed of randomly oriented long nanobelts (over 100 μm) and their side length can be controlled up to a few tens of centimetres. Also, the bulk density and surface area of these macrostructures are 3-5 mg cm(-3) and 40-80 m(2) g(-1), respectively, which are similar to those of the excellent adsorbents. In addition, the removal efficiency measurements of ammonia molecules revealed that the VPN porous structures can adsorb the ammonia molecules with the combinations of van der Waals forces and strong chemical bonding by functional groups on the VPN surface.

Assessment of sea water inundation along Daboo creek area in Indus Delta Region, Pakistan

NASA Astrophysics Data System (ADS)

Zia, Ibrahim; Zafar, Hina; Shahzad, Muhammad I.; Meraj, Mohsin; Kazmi, Jamil H.

2017-12-01

Indus Deltaic Region (IDR) in Pakistan is an erosion vulnerable coast due to the high deep water wave energy. Livelihood of millions of people depends on the fisheries and mangrove forests in IDR. IDR consists of many creeks where Daboo is a major creek located at southeast of the largest city of Pakistan, Karachi. Unfortunately, there has been no detailed study to analyze the damages of sea water intrusion at a large temporal and spatial scale. Therefore, this study is designed to estimate the effects of sea water inundation based on changing sea water surface salinity and sea surface temperature (SST). Sea surface salinity and SST data from two different surveys in Daboo creek during 1986 and 2010 are analyzed to estimate the damages and extent of sea water intrusion. Mean salinity has increased 33.33% whereas mean SST decreased 13.79% from 1987 to 2010. Spatio-temporal analysis of creek area using LANDSAT 5 Thematic mapper (TM) data for the years 1987 and 2010 shows significant amount of erosion at macro scale. Creek area has increased approximately 9.93% (260.86 m2 per year) which is roughly equal to 60 extensive sized shrimp farms. Further Land Use Land Cover (LULC) analyses for years 2001 and 2014 using LANDSAT 7 Enhanced Thematic Mapper Plus (ETM+) has indicated 42.3% decrease in cultivated land. Wet mud flats have spread out at the inner mouth of creek with enormous increase of 123.3%. Significant sea water intrusion has increased the area of barren land by 37.9%. This also resulted in overall decrease of 6.7% in area covered by mangroves. Therefore, this study recorded a significant evidence of sea water intrusion in IDR that has caused serious damages to community living in the area, economical losses. Additionally, it has also changed the environment by reducing creek biological productivity as reported by earlier studies over other regions of the world.

Wind-tunnel Modelling of Dispersion from a Scalar Area Source in Urban-Like Roughness

NASA Astrophysics Data System (ADS)

Pascheke, Frauke; Barlow, Janet F.; Robins, Alan

2008-01-01

A wind-tunnel study was conducted to investigate ventilation of scalars from urban-like geometries at neighbourhood scale by exploring two different geometries a uniform height roughness and a non-uniform height roughness, both with an equal plan and frontal density of λ p = λ f = 25%. In both configurations a sub-unit of the idealized urban surface was coated with a thin layer of naphthalene to represent area sources. The naphthalene sublimation method was used to measure directly total area-averaged transport of scalars out of the complex geometries. At the same time, naphthalene vapour concentrations controlled by the turbulent fluxes were detected using a fast Flame Ionisation Detection (FID) technique. This paper describes the novel use of a naphthalene coated surface as an area source in dispersion studies. Particular emphasis was also given to testing whether the concentration measurements were independent of Reynolds number. For low wind speeds, transfer from the naphthalene surface is determined by a combination of forced and natural convection. Compared with a propane point source release, a 25% higher free stream velocity was needed for the naphthalene area source to yield Reynolds-number-independent concentration fields. Ventilation transfer coefficients w T / U derived from the naphthalene sublimation method showed that, whilst there was enhanced vertical momentum exchange due to obstacle height variability, advection was reduced and dispersion from the source area was not enhanced. Thus, the height variability of a canopy is an important parameter when generalising urban dispersion. Fine resolution concentration measurements in the canopy showed the effect of height variability on dispersion at street scale. Rapid vertical transport in the wake of individual high-rise obstacles was found to generate elevated point-like sources. A Gaussian plume model was used to analyse differences in the downstream plumes. Intensified lateral and vertical plume spread and plume dilution with height was found for the non-uniform height roughness.

[Analysis of urban forest landscape pattern in Hefei].

PubMed

Wu, Zemin; Wu, Wenyou; Gao, Jian; Zhang, Shaojie

2003-12-01

Based on the theory and methodology of landscape ecology, the landscape pattern of the study area (17.6 km2) in the downtown of Hefei was analyzed by using the techniques of RS, GPS and GIS. The object was to provide a comprehensive method to study urban forest structure and its function in environmental improvement. The results showed that there were 5 major landscape elements, i.e., building and hard pavement surface, water, road, urban forest, and general green land in the area. The landscape matrix was building and pavement surface, occupied 73.13% of total land. Road was the typical corridor element in the city and occupied 6.89%. Green land occupied 11.44%, in which, urban forest patch occupied 9.18%. There were 408 urban forest patches, with an area of 161.16 hm2. The average area of the patch was 0.396 hm2, and the maximum area was 12 hm2. 48% of urban forest patch was identified as small scale patches with < 500 m2 of area, and only 8.6% of them was larger than 1 hm2. The number of general green land patch was 255, with an area of 39.74 hm2, which accounted for 2.26% of land area, and its average and maximum area was 0.1558 hm2 and 3.86 hm2, respectively. There were 147 water patches, with an area of 149.93 hm2, and occupied 8.54% of land, and the average and maximum area of the patch was 1.02 hm2 and 16 hm2, respectively. In the study area, both of the Shannon-Weiner landscape diversity index and evenness were low, only 0.928 and 0.576, respectively. In addition, the dominance of urban forest patch and general green land was 0.39 showing that the two landscape elements had a certain influence on the environment of the study area. The concept of interior habitat for forest was introduced in this paper, which was employed to make a scale class system of urban forest patch. The threshold area with interior habitat for urban forest patch was 9800 m2, and there was 31.69 hm2 of interior habitat of urban forest in total, which occupied 19.7% of the total area of urban forest patch. This situation was not favorable for providing more habitats to support species diversity. It's suggested that the concept of interior habitat could be employed to identify urban forest patch, and a scale system of small scale patch of urban forest-middle patch-large patch-extra large patch was build in the paper. Based on this system, the ratio of different scales of urban forest patch in the study area should be 2:2:2:3. The authors also suggested that larger pieces (1.5-3.0 hm2) of urban forest patch should be built, and more urban forests should be established in the northeastern part of the city in the future.

2012/13 abnormal cold winter in Japan associated with Large-scale Atmospheric Circulation and Local Sea Surface Temperature over the Sea of Japan

NASA Astrophysics Data System (ADS)

Ando, Y.; Ogi, M.; Tachibana, Y.

2013-12-01

On Japan, wintertime cold wave has social, economic, psychological and political impacts because of the lack of atomic power stations in the era of post Fukushima world. The colder winter is the more electricity is needed. Wintertime weather of Japan and its prediction has come under the world spotlight. The winter of 2012/13 in Japan was abnormally cold, and such a cold winter has persisted for 3 years. Wintertime climate of Japan is governed by some dominant modes of the large-scale atmospheric circulations. Yasunaka and Hanawa (2008) demonstrated that the two dominant modes - Arctic Oscillation (AO) and Western Pacific (WP) pattern - account for about 65% of the interannual variation of the wintertime mean surface air temperature of Japan. A negative AO brings about cold winter in Japan. In addition, a negative WP also brings about cold winter in Japan. Looking back to the winter of 2012/13, both the negative AO and negative WP continued from October through December. If the previous studies were correct, it would have been extremely very cold from October through December. In fact, in December, in accordance with previous studies, it was colder than normal. Contrary to the expectation, in October and November, it was, however, warmer than normal. This discrepancy signifies that an additional hidden circumstance that heats Japan overwhelms these large-scale atmospheric circulations that cool Japan. In this study, we therefore seek an additional cause of wintertime climate of Japan particularly focusing 2012 as well as the AO and WP. We found that anomalously warm oceanic temperature surrounding Japan overwhelmed influences of the AO or WP. Unlike the inland climate, the island climate can be strongly influenced by surrounding ocean temperature, suggesting that large-scale atmospheric patterns alone do not determine the climate of islands. (a) Time series of a 5-day running mean AO index (blue) as defined by Ogi et al., (2004), who called it the SVNAM index. For reference, the conventional AO index is shown by the gray line. (b) a 5-day running mean WP index, (c) area-averaged Surface Air Temperature anomalies in Japan, (d) Air Temperature anomalies, (e) heat flux anomalies, and (f) Sea Surface Temperature anomalies. The boxed area on the Sea of Japan indicates the area in which the (d)-(f) indexes were calculated.

Shape shifting predicts ontogenetic changes in metabolic scaling in diverse aquatic invertebrates.

PubMed

Glazier, Douglas S; Hirst, Andrew G; Atkinson, David

2015-03-07

Metabolism fuels all biological activities, and thus understanding its variation is fundamentally important. Much of this variation is related to body size, which is commonly believed to follow a 3/4-power scaling law. However, during ontogeny, many kinds of animals and plants show marked shifts in metabolic scaling that deviate from 3/4-power scaling predicted by general models. Here, we show that in diverse aquatic invertebrates, ontogenetic shifts in the scaling of routine metabolic rate from near isometry (bR = scaling exponent approx. 1) to negative allometry (bR < 1), or the reverse, are associated with significant changes in body shape (indexed by bL = the scaling exponent of the relationship between body mass and body length). The observed inverse correlations between bR and bL are predicted by metabolic scaling theory that emphasizes resource/waste fluxes across external body surfaces, but contradict theory that emphasizes resource transport through internal networks. Geometric estimates of the scaling of surface area (SA) with body mass (bA) further show that ontogenetic shifts in bR and bA are positively correlated. These results support new metabolic scaling theory based on SA influences that may be applied to ontogenetic shifts in bR shown by many kinds of animals and plants. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Time scales of supercooled water and implications for reversible polyamorphism

NASA Astrophysics Data System (ADS)

Limmer, David T.; Chandler, David

2015-09-01

Deeply supercooled water exhibits complex dynamics with large density fluctuations, ice coarsening and characteristic time scales extending from picoseconds to milliseconds. Here, we discuss implications of these time scales as they pertain to two-phase coexistence and to molecular simulations of supercooled water. Specifically, we argue that it is possible to discount liquid-liquid criticality because the time scales imply that correlation lengths for such behaviour would be bounded by no more than a few nanometres. Similarly, it is possible to discount two-liquid coexistence because the time scales imply a bounded interfacial free energy that cannot grow in proportion to a macroscopic surface area. From time scales alone, therefore, we see that coexisting domains of differing density in supercooled water can be no more than nanoscale transient fluctuations.

Surficial geologic map of the Heath-Northfield-Southwick-Hampden 24-quadrangle area in the Connecticut Valley region, west-central Massachusetts

USGS Publications Warehouse

Stone, Janet R.; DiGiacomo-Cohen, Mary L.

2010-01-01

The surficial geologic map layer shows the distribution of nonlithified earth materials at land surface in an area of 24 7.5-minute quadrangles (1,238 mi2 total) in west-central Massachusetts. Across Massachusetts, these materials range from a few feet to more than 500 ft in thickness. They overlie bedrock, which crops out in upland hills and as resistant ledges in valley areas. The geologic map differentiates surficial materials of Quaternary age on the basis of their lithologic characteristics (such as grain size and sedimentary structures), constructional geomorphic features, stratigraphic relationships, and age. Surficial materials also are known in engineering classifications as unconsolidated soils, which include coarse-grained soils, fine-grained soils, and organic fine-grained soils. Surficial materials underlie and are the parent materials of modern pedogenic soils, which have developed in them at the land surface. Surficial earth materials significantly affect human use of the land, and an accurate description of their distribution is particularly important for assessing water resources, construction aggregate resources, and earth-surface hazards, and for making land-use decisions. This work is part of a comprehensive study to produce a statewide digital map of the surficial geology at a 1:24,000-scale level of accuracy. This report includes explanatory text, quadrangle maps at 1:24,000 scale (PDF files), GIS data layers (ArcGIS shapefiles), metadata for the GIS layers, scanned topographic base maps (TIF), and a readme.txt file.

Surficial geologic map of the Norton-Manomet-Westport-Sconticut Neck 23-quadrangle area in southeast Massachusetts

USGS Publications Warehouse

Stone, Byron D.; Stone, Janet R.; DiGiacomo-Cohen, Mary L.; Kincare, Kevin A.

2012-01-01

The surficial geologic map shows the distribution of nonlithified earth materials at land surface in an area of 23 7.5-minute quadrangles (919 mi2 total) in southeastern Massachusetts. Across Massachusetts, these materials range from a few feet to more than 500 ft in thickness. They overlie bedrock, which crops out in upland hills and as resistant ledges in valley areas. The geologic map differentiates surficial materials of Quaternary age on the basis of their lithologic characteristics (such as grain size and sedimentary structures), constructional geomorphic features, stratigraphic relationships, and age. Surficial materials also are known in engineering classifications as unconsolidated soils, which include coarse-grained soils, fine-grained soils, and organic fine-grained soils. Surficial materials underlie and are the parent materials of modern pedogenic soils, which have developed in them at the land surface. Surficial earth materials significantly affect human use of the land, and an accurate description of their distribution is particularly important for assessing water resources, construction aggregate resources, and earth-surface hazards, and for making land-use decisions. This work is part of a comprehensive study to produce a statewide digital map of the surficial geology at a 1:24,000-scale level of accuracy. This report includes explanatory text (PDF), quadrangle maps at 1:24,000 scale (PDF files), GIS data layers (ArcGIS shapefiles), metadata for the GIS layers, scanned topographic base maps (TIF), and a readme.txt file.

Surficial geologic map of the Mount Grace-Ashburnham-Monson-Webster 24-quadrangle area in central Massachusetts

USGS Publications Warehouse

Stone, Janet R.

2013-01-01

The surficial geologic map shows the distribution of nonlithified earth materials at land surface in an area of 24 7.5-minute quadrangles (1,238 mi2 total) in central Massachusetts. Across Massachusetts, these materials range from a few feet to more than 500 ft in thickness. They overlie bedrock, which crops out in upland hills and as resistant ledges in valley areas. The geologic map differentiates surficial materials of Quaternary age on the basis of their lithologic characteristics (such as grain size and sedimentary structures), constructional geomorphic features, stratigraphic relationships, and age. Surficial materials also are known in engineering classifications as unconsolidated soils, which include coarse-grained soils, fine-grained soils, and organic fine-grained soils. Surficial materials underlie and are the parent materials of modern pedogenic soils, which have developed in them at the land surface. Surficial earth materials significantly affect human use of the land, and an accurate description of their distribution is particularly important for assessing water resources, construction-aggregate resources, and earth-surface hazards, and for making land-use decisions. This work is part of a comprehensive study to produce a statewide digital map of the surficial geology at a 1:24,000-scale level of accuracy. This report includes explanatory text (PDF), quadrangle maps at 1:24,000 scale (PDF files), GIS data layers (ArcGIS shapefiles), metadata for the GIS layers, scanned topographic base maps (TIF), and a readme.txt file.

Developing satellite-derived estimates of surface moisture status

NASA Technical Reports Server (NTRS)

Nemani, Ramakhrishna; Pierce, Lars; Running, Steve; Goward, Samuel

1993-01-01

An evaluation is made of the remotely sensed surface temperature (Ts)/normalized difference vegetation index (NDVI) relationship in studies of the influence of biome type on the slope of Ts/NDVI, and of the automation of the process of defining the relationship so that the surface moisture status can be compared with Ts/NDVI at continental scales. The analysis is conducted using the NOAA AVHRR over a 300 x 300 km area in western Montana, as well as biweekly composite AVHRR data. A strong negative relationship is established between NDVI and Ts over all biome types.

Nanotube Surface Arrays: Weaving, Bending, and Assembling on Patterned Silicon

NASA Astrophysics Data System (ADS)

Tsukruk, Vladimir V.; Ko, Hyunhyub; Peleshanko, Sergiy

2004-02-01

We report the fabrication of ordered arrays of oriented and bent carbon nanotube on a patterned silicon surface with a micron scale spacing extending over millimeter size surface areas. We suggest that the patterning is controlled by the hydrodynamic behavior of a fluid front and orientation and bending mechanisms are facilitated by the pinned carbon nanotubes trapped by the liquid-solid-vapor contact line. The bending of the pinned nanotubes occurs along the shrinking receding front of the drying microdroplets. The formation of stratified microfluidic layers is vital for stimulating periodic instabilities of the contact line.

Can Regional Climate Models be used in the assessment of vulnerability and risk caused by extreme events?

NASA Astrophysics Data System (ADS)

Nunes, Ana

2015-04-01

Extreme meteorological events played an important role in catastrophic occurrences observed in the past over densely populated areas in Brazil. This motived the proposal of an integrated system for analysis and assessment of vulnerability and risk caused by extreme events in urban areas that are particularly affected by complex topography. That requires a multi-scale approach, which is centered on a regional modeling system, consisting of a regional (spectral) climate model coupled to a land-surface scheme. This regional modeling system employs a boundary forcing method based on scale-selective bias correction and assimilation of satellite-based precipitation estimates. Scale-selective bias correction is a method similar to the spectral nudging technique for dynamical downscaling that allows internal modes to develop in agreement with the large-scale features, while the precipitation assimilation procedure improves the modeled deep-convection and drives the land-surface scheme variables. Here, the scale-selective bias correction acts only on the rotational part of the wind field, letting the precipitation assimilation procedure to correct moisture convergence, in order to reconstruct South American current climate within the South American Hydroclimate Reconstruction Project. The hydroclimate reconstruction outputs might eventually produce improved initial conditions for high-resolution numerical integrations in metropolitan regions, generating more reliable short-term precipitation predictions, and providing accurate hidrometeorological variables to higher resolution geomorphological models. Better representation of deep-convection from intermediate scales is relevant when the resolution of the regional modeling system is refined by any method to meet the scale of geomorphological dynamic models of stability and mass movement, assisting in the assessment of risk areas and estimation of terrain stability over complex topography. The reconstruction of past extreme events also helps the development of a system for decision-making, regarding natural and social disasters, and reducing impacts. Numerical experiments using this regional modeling system successfully modeled severe weather events in Brazil. Comparisons with the NCEP Climate Forecast System Reanalysis outputs were made at resolutions of about 40- and 25-km of the regional climate model.

Stormwater management network effectiveness and implications for urban watershed function: A critical review

USGS Publications Warehouse

Jefferson, Anne J.; Bhaskar, Aditi S.; Hopkins, Kristina G.; Fanelli, Rosemary; Avellaneda, Pedro M.; McMillan, Sara K.

2017-01-01

Deleterious effects of urban stormwater are widely recognized. In several countries, regulations have been put into place to improve the conditions of receiving water bodies, but planning and engineering of stormwater control is typically carried out at smaller scales. Quantifying cumulative effectiveness of many stormwater control measures on a watershed scale is critical to understanding how small-scale practices translate to urban river health. We review 100 empirical and modelling studies of stormwater management effectiveness at the watershed scale in diverse physiographic settings. Effects of networks with stormwater control measures (SCMs) that promote infiltration and harvest have been more intensively studied than have detention-based SCM networks. Studies of peak flows and flow volumes are common, whereas baseflow, groundwater recharge, and evapotranspiration have received comparatively little attention. Export of nutrients and suspended sediments have been the primary water quality focus in the United States, whereas metals, particularly those associated with sediments, have received greater attention in Europe and Australia. Often, quantifying cumulative effects of stormwater management is complicated by needing to separate its signal from the signal of urbanization itself, innate watershed characteristics that lead to a range of hydrologic and water quality responses, and the varying functions of multiple types of SCMs. Biases in geographic distribution of study areas, and size and impervious surface cover of watersheds studied also limit our understanding of responses. We propose hysteretic trajectories for how watershed function responds to increasing imperviousness and stormwater management. Even where impervious area is treated with SCMs, watershed function may not be restored to its predevelopment condition because of the lack of treatment of all stormwater generated from impervious surfaces; non-additive effects of individual SCMs; and persistence of urban effects beyond impervious surfaces. In most cases, pollutant load decreases largely result from run-off reductions rather than lowered solute or particulate concentrations. Understanding interactions between natural and built landscapes, including stormwater management strategies, is critical for successfully managing detrimental impacts of stormwater at the watershed scale.

Sea Surface Temperature Influence on Terrestrial Gross Primary Production along the Southern California Current.

PubMed

Reimer, Janet J; Vargas, Rodrigo; Rivas, David; Gaxiola-Castro, Gilberto; Hernandez-Ayon, J Martin; Lara-Lara, Ruben

2015-01-01

Some land and ocean processes are related through connections (and synoptic-scale teleconnections) to the atmosphere. Synoptic-scale atmospheric (El Niño/Southern Oscillation [ENSO], Pacific Decadal Oscillation [PDO], and North Atlantic Oscillation [NAO]) decadal cycles are known to influence the global terrestrial carbon cycle. Potentially, smaller scale land-ocean connections influenced by coastal upwelling (changes in sea surface temperature) may be important for local-to-regional water-limited ecosystems where plants may benefit from air moisture transported from the ocean to terrestrial ecosystems. Here we use satellite-derived observations to test potential connections between changes in sea surface temperature (SST) in regions with strong coastal upwelling and terrestrial gross primary production (GPP) across the Baja California Peninsula. This region is characterized by an arid/semiarid climate along the southern California Current. We found that SST was correlated with the fraction of photosynthetic active radiation (fPAR; as a proxy for GPP) with lags ranging from 0 to 5 months. In contrast ENSO was not as strongly related with fPAR as SST in these coastal ecosystems. Our results show the importance of local-scale changes in SST during upwelling events, to explain the variability in GPP in coastal, water-limited ecosystems. The response of GPP to SST was spatially-dependent: colder SST in the northern areas increased GPP (likely by influencing fog formation), while warmer SST at the southern areas was associated to higher GPP (as SST is in phase with precipitation patterns). Interannual trends in fPAR are also spatially variable along the Baja California Peninsula with increasing secular trends in subtropical regions, decreasing trends in the most arid region, and no trend in the semi-arid regions. These findings suggest that studies and ecosystem process based models should consider the lateral influence of local-scale ocean processes that could influence coastal ecosystem productivity.

Sea Surface Temperature Influence on Terrestrial Gross Primary Production along the Southern California Current

PubMed Central

Reimer, Janet J.; Vargas, Rodrigo; Rivas, David; Gaxiola-Castro, Gilberto; Hernandez-Ayon, J. Martin; Lara-Lara, Ruben

2015-01-01

Some land and ocean processes are related through connections (and synoptic-scale teleconnections) to the atmosphere. Synoptic-scale atmospheric (El Niño/Southern Oscillation [ENSO], Pacific Decadal Oscillation [PDO], and North Atlantic Oscillation [NAO]) decadal cycles are known to influence the global terrestrial carbon cycle. Potentially, smaller scale land-ocean connections influenced by coastal upwelling (changes in sea surface temperature) may be important for local-to-regional water-limited ecosystems where plants may benefit from air moisture transported from the ocean to terrestrial ecosystems. Here we use satellite-derived observations to test potential connections between changes in sea surface temperature (SST) in regions with strong coastal upwelling and terrestrial gross primary production (GPP) across the Baja California Peninsula. This region is characterized by an arid/semiarid climate along the southern California Current. We found that SST was correlated with the fraction of photosynthetic active radiation (fPAR; as a proxy for GPP) with lags ranging from 0 to 5 months. In contrast ENSO was not as strongly related with fPAR as SST in these coastal ecosystems. Our results show the importance of local-scale changes in SST during upwelling events, to explain the variability in GPP in coastal, water-limited ecosystems. The response of GPP to SST was spatially-dependent: colder SST in the northern areas increased GPP (likely by influencing fog formation), while warmer SST at the southern areas was associated to higher GPP (as SST is in phase with precipitation patterns). Interannual trends in fPAR are also spatially variable along the Baja California Peninsula with increasing secular trends in subtropical regions, decreasing trends in the most arid region, and no trend in the semi-arid regions. These findings suggest that studies and ecosystem process based models should consider the lateral influence of local-scale ocean processes that could influence coastal ecosystem productivity. PMID:25923109

A fast, parallel algorithm to solve the basic fluvial erosion/transport equations

NASA Astrophysics Data System (ADS)

Braun, J.

2012-04-01

Quantitative models of landform evolution are commonly based on the solution of a set of equations representing the processes of fluvial erosion, transport and deposition, which leads to predict the geometry of a river channel network and its evolution through time. The river network is often regarded as the backbone of any surface processes model (SPM) that might include other physical processes acting at a range of spatial and temporal scales along hill slopes. The basic laws of fluvial erosion requires the computation of local (slope) and non-local (drainage area) quantities at every point of a given landscape, a computationally expensive operation which limits the resolution of most SPMs. I present here an algorithm to compute the various components required in the parameterization of fluvial erosion (and transport) and thus solve the basic fluvial geomorphic equation, that is very efficient because it is O(n) (the number of required arithmetic operations is linearly proportional to the number of nodes defining the landscape), and is fully parallelizable (the computation cost decreases in a direct inverse proportion to the number of processors used to solve the problem). The algorithm is ideally suited for use on latest multi-core processors. Using this new technique, geomorphic problems can be solved at an unprecedented resolution (typically of the order of 10,000 X 10,000 nodes) while keeping the computational cost reasonable (order 1 sec per time step). Furthermore, I will show that the algorithm is applicable to any regular or irregular representation of the landform, and is such that the temporal evolution of the landform can be discretized by a fully implicit time-marching algorithm, making it unconditionally stable. I will demonstrate that such an efficient algorithm is ideally suited to produce a fully predictive SPM that links observationally based parameterizations of small-scale processes to the evolution of large-scale features of the landscapes on geological time scales. It can also be used to model surface processes at the continental or planetary scale and be linked to lithospheric or mantle flow models to predict the potential interactions between tectonics driving surface uplift in orogenic areas, mantle flow producing dynamic topography on continental scales and surface processes.

The acid-base titration of montmorillonite

NASA Astrophysics Data System (ADS)

Bourg, I. C.; Sposito, G.; Bourg, A. C.

2003-12-01

Proton binding to clay minerals plays an important role in the chemical reactivity of soils (e.g., acidification, retention of nutrients or pollutants). If should also affect the performance of clay barriers for waste disposal. The surface acidity of clay minerals is commonly modelled empirically by assuming generic amphoteric surface sites (>SOH) on a flat surface, with fitted site densities and acidity constant. Current advances in experimental methods (notably spectroscopy) are rapidly improving our understanding of the structure and reactivity of the surface of clay minerals (arrangement of the particles, nature of the reactive surface sites, adsorption mechanisms). These developments are motivated by the difficulty of modelling the surface chemistry of mineral surfaces at the macro-scale (e.g., adsorption or titration) without a detailed (molecular-scale) picture of the mechanisms, and should be progressively incorporated into surface complexation models. In this view, we have combined recent estimates of montmorillonite surface properties (surface site density and structure, edge surface area, surface electrostatic potential) with surface site acidities obtained from the titration of alpha-Al2O3 and SiO2, and a novel method of accounting for the unknown initial net proton surface charge of the solid. The model predictions were compared to experimental titrations of SWy-1 montmorillonite and purified MX-80 bentonite in 0.1-0.5 mol/L NaClO4 and 0.005-0.5 mol/L NaNO3 background electrolytes, respectively. Most of the experimental data were appropriately described by the model after we adjusted a single parameter (silanol sites on the surface of montmorillonite were made to be slightly more acidic than those of silica). At low ionic strength and acidic pH the model underestimated the buffering capacity of the montmorillonite, perhaps due to clay swelling or to the interlayer adsorption of dissolved aluminum. The agreement between our model and the experimental data illustrates the complementarity of molecular and macro-scale descriptions of the clay reactivity.

Fractography of glass at the nanometer scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guilloteau, E.; Arribart, H.; Creuzet, F.

1996-12-01

The authors present a nanometer scale description of the fracture surface of soda-lime glass. This is achieved by the use of Atomic Force Microscopy. The mirror zone is shown to be built with elementary entities, the density of which increases continuously while the mist and hackle zones are approached. Moreover, the overall picture leads to some kind of self-similarity, in the sense that small regions of the hackle zone exhibit the full set of mirror, mist and hackle areas.