Accommodating the ecological fallacy in disease mapping in the absence of individual exposures.

PubMed

Wang, Feifei; Wang, Jian; Gelfand, Alan; Li, Fan

2017-12-30

In health exposure modeling, in particular, disease mapping, the ecological fallacy arises because the relationship between aggregated disease incidence on areal units and average exposure on those units differs from the relationship between the event of individual incidence and the associated individual exposure. This article presents a novel modeling approach to address the ecological fallacy in the least informative data setting. We assume the known population at risk with an observed incidence for a collection of areal units and, separately, environmental exposure recorded during the period of incidence at a collection of monitoring stations. We do not assume any partial individual level information or random allocation of individuals to observed exposures. We specify a conceptual incidence surface over the study region as a function of an exposure surface resulting in a stochastic integral of the block average disease incidence. The true block level incidence is an unavailable Monte Carlo integration for this stochastic integral. We propose an alternative manageable Monte Carlo integration for the integral. Modeling in this setting is immediately hierarchical, and we fit our model within a Bayesian framework. To alleviate the resulting computational burden, we offer 2 strategies for efficient model fitting: one is through modularization, the other is through sparse or dimension-reduced Gaussian processes. We illustrate the performance of our model with simulations based on a heat-related mortality dataset in Ohio and then analyze associated real data. Copyright © 2017 John Wiley & Sons, Ltd.

Nucleation and growth kinetics during metal-induced layer exchange crystallization of Ge thin films at low temperatures

NASA Astrophysics Data System (ADS)

Hu, Shu; McIntyre, Paul C.

2012-02-01

The kinetics of Al-catalyzed layer exchange crystallization of amorphous germanium (Ge) thin films at low temperatures is reported. Observation of Ge mass transport from an underlying amorphous Ge layer to the Al film surface through an interposed sub-nanometer GeOx interfacial layer allows independent measurement of the areal density and average area of crystalline Ge islands formed on the film surface. We show that bias-voltage stressing of the interfacial layer can be used to control the areal density of nucleated Ge islands. Based on experimental observations, the Johnson-Mehl-Avrami-Kolmogorov phase transformation theory is used to model nanoscale nucleation and growth of Ge islands in two dimensions. Ge island nucleation kinetics follows an exponentially decaying nucleation rate with time. Ge island growth kinetics switches from linear growth at a constant growth velocity to diffusion-limited growth as the growth front advances. The transition point between these two regimes depends on the Ge nucleation site density and the annealing temperature. Knowledge of the kinetics of low-temperature crystallization is important in achieving textured polycrystalline Ge thin films with large grains for applications in large-area electronics and solar energy conversion.

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.

Ultrathin NiO nanoflakes electrode materials for supercapacitors

NASA Astrophysics Data System (ADS)

Xiao, Huanhao; Qu, Fengyu; Wu, Xiang

2016-01-01

In this work, large scale ultrathin NiO nanoflakes grown on nickel foam have been successfully obtained by a facile, low cost and eco-friendly route under mild temperature. The average thickness of the as-obtained NiO nanoflakes is about 10 nm. And they possess large surface area of 89.56 m2 g-1 and the dominant pore size of 2.313 nm. The electrochemical properties of the obtained product were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge measurement and electrochemical impedance spectroscopy (EIS). The electrochemical tests demonstrate the highest discharge areal capacitance of 870 mF cm-2 at 1 mA cm-2 and excellent long cycle-life stability with 84.2% of its discharge areal capacitance retention after 6000 cycles at the current density of 10 mA cm-2. The remarkable electrochemical capacitive performance revealed NiO nanoflakes grown on nickel foam might be promising supercapacitor electrode materials for future energy storage applications.

High-Areal-Density Fuel Assembly in Direct-Drive Cryogenic Implosions

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

Sangster, T.C.; Goncharov, V.N.; Radha, P.B.

The first observation of ignition-relevant areal-density deuterium from implosions of capsules with cryogenic fuel layers at ignition-relevant adiabats is reported. The experiments were performed on the 60-beam, 30-kJUV OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. Neutron-averaged areal densities of 202+-7 mg/cm^2 and 182+-7 mg/cm^2 (corresponding to estimated peak fuel densities in excess of 100 g/cm^3) were inferred using an 18-kJ direct-drive pulse designed to put the converging fuel on an adiabat of 2.5. These areal densities are in good agreement with the predictions of hydrodynamic simulations indicating that the fuel adiabat can be accuratelymore » controlled under ignition-relevant conditions.« less

Increased shell entropy as an explanation for observed decreased shell areal densities in OMEGA implosions

NASA Astrophysics Data System (ADS)

Hoffman, Nelson; Herrmann, Hans; Kim, Yongho

2014-10-01

A reduced ion-kinetic (RIK) model used in hydrodynamic simulations has had some success in explaining time- and space-averaged observables characterizing the fusion fuel in hot low-density ICF capsule implosions driven by 1-ns 60-beam laser pulses at OMEGA. But observables characterizing the capsule shell, e.g., the areal density of 12C in a plastic shell, have proved harder to explain. Recently we have found that assuming the shell has higher entropy than expected in a 1D laser-driven RIK simulation allows an explanation of the observed values of 12C areal density, and its dependence on initial shell thickness in a set of DT-filled plastic capsules. If, for example, a 15- μm CH shell implodes on an adiabat two to three times higher than predicted in a typical unmodified RIK simulation, the calculated burn-averaged shell areal density decreases from ~80 mg/cm2 in the unmodified simulation to the observed value of ~25 mg/cm2. We discuss possible mechanisms that could lead to increased entropy in such implosions. Research supported by U.S. Department of Energy under Contract DE-AC52-06NA25396.

X-ray microanalytical surveys of minor element concentrations in unsectioned biological samples

NASA Astrophysics Data System (ADS)

Schofield, R. M. S.; Lefevre, H. W.; Overley, J. C.; Macdonald, J. D.

1988-03-01

Approximate concentration maps of small unsectioned biological samples are made using the pixel by pixel ratio of PIXE images to areal density images. Areal density images are derived from scanning transmission ion microscopy (STIM) proton energy-loss images. Corrections for X-ray production cross section variations, X-ray attenuation, and depth averaging are approximated or ignored. Estimates of the magnitude of the resulting error are made. Approximate calcium concentrations within the head of a fruit fly are reported. Concentrations in the retinula cell region of the eye average about 1 mg/g dry weight. Concentrations of zinc in the mandible of several ant species average about 40 mg/g. Zinc concentrations in the stomachs of these ants are at least 1 mg/g.

The Galapagos Spreading Center at 86°W: A detailed geothermal field study

NASA Astrophysics Data System (ADS)

Green, Kenneth E.; von Herzen, Richard P.; Williams, David L.

1981-02-01

Appendix is available with entire article on microfiche. Orderfrom American Geophysical Union, 2000 Florida Avenue, N.W.,Washington, D.C. 20009. Document J80-013; $01.00. Payment mustaccompany order. We report here measurements of the heat flow field of the Galapagos Spreading Center on crust of age less than 1.0 m.y. The 443 measurements in an area of about 570 km2 reveal the general planform of the geothermal flux and permit the first truly areal estimate of the near-axis conductive heat flux. The intrusion process and associated hydrothermal circulation dominate the surface heat flow pattern, with circulation apparently continuing beyond the limits of our survey. The areal average of the conductive heat flux is 7.1 ± 0.8 HFU (295 ± 33 mW/m2), about one-third the heat flux predicted by plate models. The remaining heat is apparently removed by venting of hydrothermal waters at the spreading axis and through basalt outcrops and hydrothermal mounds off axis. The pattern of surface heat flux is lineated parallel to the axis and the strongly lineated topography. Sharp lateral gradients in the heat flow, greater than 10 HFU/km near escarpments and commonly expressed as high heat flow at the tops of the scarps and lower heat flow in the valleys, may indicate a local concentration of the circulation by surface fault systems and/or variable sediment thickness.

Sulfide and methane production in sewer sediments.

PubMed

Liu, Yiwen; Ni, Bing-Jie; Ganigué, Ramon; Werner, Ursula; Sharma, Keshab R; Yuan, Zhiguo

2015-03-01

Recent studies have demonstrated significant sulfide and methane production by sewer biofilms, particularly in rising mains. Sewer sediments in gravity sewers are also biologically active; however, their contribution to biological transformations in sewers is poorly understood at present. In this study, sediments collected from a gravity sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments. Batch test results show significant sulfide production with an average rate of 9.20 ± 0.39 g S/m(2)·d from the sediments, which is significantly higher than the areal rate of sewer biofilms. In contrast, the average methane production rate is 1.56 ± 0.14 g CH4/m(2)·d at 20 °C, which is comparable to the areal rate of sewer biofilms. These results clearly show that the contributions of sewer sediments to sulfide and methane production cannot be ignored when evaluating sewer emissions. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial profiling along the depth of the sediments and mathematical modelling reveal that sulfide production takes place near the sediment surface due to the limited penetration of sulfate. In comparison, methane production occurs in a much deeper zone below the surface likely due to the better penetration of soluble organic carbon. Modelling results illustrate the dependency of sulfide and methane productions on the bulk sulfate and soluble organic carbon concentrations can be well described with half-order kinetics. Copyright © 2014 Elsevier Ltd. All rights reserved.

High-Areal-Density Fuel Assembly in Direct-Drive Cryogenic Implosions

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

Sangster, T. C.; Goncharov, V. N.; Radha, P. B.

The first observation of ignition-relevant areal-density deuterium from implosions of capsules with cryogenic fuel layers at ignition-relevant adiabats is reported. The experiments were performed on the 60-beam, 30-kJ{sub UV} OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. Neutron-averaged areal densities of 202{+-}7 mg/cm{sup 2} and 182{+-}7 mg/cm{sup 2} (corresponding to estimated peak fuel densities in excess of 100 g/cm{sup 3}) were inferred using an 18-kJ direct-drive pulse designed to put the converging fuel on an adiabat of 2.5. These areal densities are in good agreement with the predictions of hydrodynamic simulations indicating that the fuelmore » adiabat can be accurately controlled under ignition-relevant conditions.« less

Estimating areal production of intertidal microphytobenthos based on spatio-temporal community dynamics and laboratory measurements

NASA Astrophysics Data System (ADS)

Du, Guo Ying; Chung, Ik Kyo

2009-12-01

In situ Microphytobenthic community dynamics were combined with laboratory measurement of predominant species by fluorescence methods to estimate the areal primary production. Field investigation of community dynamics of microphytobenthos (MPB) was conducted from August 2006 to August 2007 in intertidal flats of the Nakdong River estuary, Korea. MPB Biomass varied between 0.47 and 16.58 μg cm-3 in the surface 1 cm sediment, with two dominant diatom species, Amphora coffeaeformis and Navicula sp., occupying average 77.2 ± 14.9% of total number of MPB cells. The biomass was higher in the slightly muddy sand sites than that in the sand site, and showed different pattern of seasonal variation. The profile of vertical distribution of biomass was an exponential decrease trend with depth in sediments. The biomass proportions in the uppermost 3 mm were 57.6% and 37.8% with and without the presence of biofilm, respectively. The two dominant species were cultured in laboratory, and their photosynthetic parameters, rETRmax (relative maximum electron transport rate), α (light utilization coefficient) and E k (light saturation parameter) were derived from rETR (relative ETR)-irradiance curves by Imaging- PAM (pulse amplitude modulated) fluorometry. The rETR-irradiance curves showed no significant difference of photosynthetic activities between the two species. The areal potential production ranged from 0.74 to 2.22 g C m-2 d-1.

Manganese oxide micro-supercapacitors with ultra-high areal capacitance

NASA Astrophysics Data System (ADS)

Wang, Xu; Myers, Benjamin D.; Yan, Jian; Shekhawat, Gajendra; Dravid, Vinayak; Lee, Pooi See

2013-05-01

A symmetric micro-supercapacitor is constructed by electrochemically depositing manganese oxide onto micro-patterned current collectors. High surface-to-volume ratio of manganese oxide and short diffusion distance between electrodes give an ultra-high areal capacitance of 56.3 mF cm-2 at a current density of 27.2 μA cm-2.A symmetric micro-supercapacitor is constructed by electrochemically depositing manganese oxide onto micro-patterned current collectors. High surface-to-volume ratio of manganese oxide and short diffusion distance between electrodes give an ultra-high areal capacitance of 56.3 mF cm-2 at a current density of 27.2 μA cm-2. Electronic supplementary information (ESI) available: Experimental procedures; optical images of micro-supercapacitors; areal capacitances of samples M-0.3C, M-0.6C and M-0.9C; illustration of interdigital finger electrodes; Nyquist plot of Co(OH)2 deposited on micro-electrodes. See DOI: 10.1039/c3nr00210a

The topographic development and areal parametric characterization of a stratified surface polished by mass finishing

NASA Astrophysics Data System (ADS)

Walton, Karl; Blunt, Liam; Fleming, Leigh

2015-09-01

Mass finishing is amongst the most widely used finishing processes in modern manufacturing, in applications from deburring to edge radiusing and polishing. Processing objectives are varied, ranging from the cosmetic to the functionally critical. One such critical application is the hydraulically smooth polishing of aero engine component gas-washed surfaces. In this, and many other applications the drive to improve process control and finish tolerance is ever present. Considering its widespread use mass finishing has seen limited research activity, particularly with respect to surface characterization. The objectives of the current paper are to; characterise the mass finished stratified surface and its development process using areal surface parameters, provide guidance on the optimal parameters and sampling method to characterise this surface type for a given application, and detail the spatial variation in surface topography due to coupon edge shadowing. Blasted and peened square plate coupons in titanium alloy are wet (vibro) mass finished iteratively with increasing duration. Measurement fields are precisely relocated between iterations by fixturing and an image superimposition alignment technique. Surface topography development is detailed with ‘log of process duration’ plots of the ‘areal parameters for scale-limited stratified functional surfaces’, (the Sk family). Characteristic features of the Smr2 plot are seen to map out the processing of peak, core and dale regions in turn. These surface process regions also become apparent in the ‘log of process duration’ plot for Sq, where lower core and dale regions are well modelled by logarithmic functions. Surface finish (Ra or Sa) with mass finishing duration is currently predicted with an exponential model. This model is shown to be limited for the current surface type at a critical range of surface finishes. Statistical analysis provides a group of areal parameters including; Vvc, Sq, and Sdq, showing optimal discrimination for a specific range of surface finish outcomes. As a consequence of edge shadowing surface segregation is suggested for characterization purposes.

Estimation of surface heat and moisture fluxes over a prairie grassland. II - Two-dimensional time filtering and site variability

NASA Technical Reports Server (NTRS)

Crosson, William L.; Smith, Eric A.

1992-01-01

The behavior of in situ measurements of surface fluxes obtained during FIFE 1987 is examined by using correlative and spectral techniques in order to assess the significance of fluctuations on various time scales, from subdiurnal up to synoptic, intraseasonal, and annual scales. The objectives of this analysis are: (1) to determine which temporal scales have a significant impact on areal averaged fluxes and (2) to design a procedure for filtering an extended flux time series that preserves the basic diurnal features and longer time scales while removing high frequency noise that cannot be attributed to site-induced variation. These objectives are accomplished through the use of a two-dimensional cross-time Fourier transform, which serves to separate processes inherently related to diurnal and subdiurnal variability from those which impact flux variations on the longer time scales. A filtering procedure is desirable before the measurements are utilized as input with an experimental biosphere model, to insure that model based intercomparisons at multiple sites are uncontaminated by input variance not related to true site behavior. Analysis of the spectral decomposition indicates that subdiurnal time scales having periods shorter than 6 hours have little site-to-site consistency and therefore little impact on areal integrated fluxes.

Effects of shock-breakout pressure on ejection of micron-scale material from shocked tin surfaces

NASA Astrophysics Data System (ADS)

Zellner, M. B.; Grover, M.; Hammerberg, J. E.; Hixson, R. S.; Iverson, A. J.; Macrum, G. S.; Morley, K. B.; Obst, A. W.; Olson, R. T.; Payton, J. R.; Rigg, P. A.; Routley, N.; Stevens, G. D.; Turley, W. D.; Veeser, L.; Buttler, W. T.

2007-07-01

This effort investigates the relation between ejecta production and shock-breakout pressure (PSB) for Sn shocked with a Taylor shockwave (unsupported) to pressures near the solid-on-release/partial melt-on-release phase transition region. The shockwaves were created by detonation of high explosive (HE) PBX-9501 on the front side of Sn coupons. Ejecta production at the backside or free side of the Sn coupons was characterized through use of piezoelectric pins, optical shadowgraphy, x-ray attenuation radiography, and optical-heterodyne velocimetry. Ejecta velocities, dynamic volume densities, and areal densities were then correlated with the shock-breakout pressure of Sn surfaces characterized by roughness average of Ra=16 μin or Ra=32 μin.

Cage Regional Energy Budgets from the GLAS 4TH Order Model

NASA Technical Reports Server (NTRS)

Herman, G. F.; Alexder, M. A.; Shubert, S. D.

1984-01-01

The status and future plans of a study to (1) assess the accuracy of regional energy balance calculations obtained from the 4th-order model, (2) determine the impact of satellite data on the calculations, and (3) determine their utility for ocean energy transport studies are discussed. An equation is presented which models the vertically-integrated, time and areally-averaged total energy content of a region of the atmosphere extending from the surface to the top of the atmosphere. All of the terms of the equation were evaluated using early versions of the GLAS FGGE IIIb analysis, and analysis with satellite data deleted. Results show that the budget is dominated by the surface fluxes, net radiation, and horizontal atmospoheric divergence.

Mass-velocity and size-velocity distributions of ejecta cloud from shock-loaded tin surface using large scale molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Durand, Olivier; Soulard, Laurent

2015-06-01

The mass (volume and areal densities) versus velocity as well as the size versus velocity distributions of a shock-induced cloud of particles are investigated using large scale molecular dynamics (MD) simulations. A generic 3D tin crystal with a sinusoidal free surface roughness is set in contact with vacuum and shock-loaded so that it melts directly on shock. At the reflection of the shock wave onto the perturbations of the free surface, 2D sheets/jets of liquid metal are ejected. The simulations show that the distributions may be described by an analytical model based on the propagation of a fragmentation zone, from the tip of the sheets to the free surface, within which the kinetic energy of the atoms decreases as this zone comes closer to the free surface on late times. As this kinetic energy drives (i) the (self-similar) expansion of the zone once it has broken away from the sheet and (ii) the average size of the particles which result from fragmentation in the zone, the ejected mass and the average size of the particles progressively increase in the cloud as fragmentation occurs closer to the free surface. Though relative to nanometric scales, our model reproduces quantitatively experimental profiles and may help in their analysis.

Calibration of areal surface topography measuring instruments

NASA Astrophysics Data System (ADS)

Seewig, J.; Eifler, M.

2017-06-01

The ISO standards which are related to the calibration of areal surface topography measuring instruments are the ISO 25178-6xx series which defines the relevant metrological characteristics for the calibration of different measuring principles and the ISO 25178-7xx series which defines the actual calibration procedures. As the field of areal measurement is however not yet fully standardized, there are still open questions to be addressed which are subject to current research. Based on this, selected research results of the authors in this area are presented. This includes the design and fabrication of areal material measures. For this topic, two examples are presented with the direct laser writing of a stepless material measure for the calibration of the height axis which is based on the Abbott- Curve and the manufacturing of a Siemens star for the determination of the lateral resolution limit. Based on these results, as well a new definition for the resolution criterion, the small scale fidelity, which is still under discussion, is presented. Additionally, a software solution for automated calibration procedures is outlined.

Mechanical algal disruption for efficient biodiesel extraction

NASA Astrophysics Data System (ADS)

Krehbiel, Joel David

Biodiesel from algae provides several benefits over current biodiesel feedstocks, but the energy requirements of processing algae into a useable fuel are currently so high as to be prohibitive. One route to improving this is via disruption of the cells prior to lipid extraction, which can significantly increase energy recovery. Unfortunately, several obvious disruption techniques require more energy than can be gained. This dissertation examines the use of microbubbles to improve mechanical disruption of algal cells using experimental, theoretical, and computational methods. New laboratory experiments show that effective ultrasonic disruption of algae is achieved by adding microbubbles to an algal solution. The configuration studied flows the solution through a tube and insonifies a small section with a high-pressure ultrasound wave. Previous biomedical research has shown effective cell membrane damage on animal cells with similar methods, but the present research is the first to extend such study to algal cells. Results indicate that disruption increases with peak negative pressure between 1.90 and 3.07 MPa and with microbubble concentration up to 12.5 x 107 bubbles/ml. Energy estimates of this process suggest that it requires only one-fourth the currently most-efficient laboratory-scale disruption process. Estimates of the radius near each bubble that causes disruption (i.e. the disruption radius) suggest that it increases with peak negative pressure and is near 9--20 microm for all cases tested. It is anticipated that these procedures can be designed for better efficiency and efficacy, which will be facilitated by identifying the root mechanisms of the bubble-induced disruption. We therefore examine whether bubble expansion alone creates sufficient cell deformation for cell rupture. The spherically-symmetric Marmottant model for bubble dynamics allows estimation of the flow regime under experimental conditions. Bubble expansion is modeled as a point source of mass at the bubble center, and if the bubble-to-cell spacing is much larger than the cell radius, the flow around the cell is approximately extensional in the cell's frame of reference. It is known that the present algae are quasi-spherical with cytoplasmic viscosity approximately 100 times that of water, so the cell is approximated as a viscous sphere. Thus, conditions that cause cell disruption from an expanding microbubble are modeled as either steady inviscid extensional flow or steady point source flow over a viscous sphere. In the inviscid extensional flow model, the flow inside the sphere is dominated by viscous forces so the Stokes equation is solved with matched stresses at the sphere surface from the exterior inviscid extensional flow. The short-time deformation of the sphere surface suggests that inviscid extensional flow is insufficient to disrupt cells. This indicates that asymmetry of the flow over the sphere may be required to provide sufficient surface areal strain to rupture the cell. In a more detailed model, the bubble expansion is modeled as an expansion near a viscous sphere using finite element software. For conditions similar to those seen in the experiment, deformation shows similar scaling to disruption. The deformation in this model is significantly higher than predicted from the inviscid extensional flow model due to the effect of asymmetric flow on the cell membrane. Estimates suggest 21% average areal strain on the algal membrane is required to disrupt algal cells, and this result agrees well with areal strains typically required to disrupt cell membranes although the actual value would be lessened by the effect of an elastic membrane, which is neglected in the present model. The local areal strain on the sphere surface is a maximum closest to the point source, and there is compressive strain near theta = +/-pi/4 with theta the angle from the line between the cell center and the point source. The maximum local areal strain shows less sensitivity to the viscosity of the interior fluid than the average areal strain. Overall, the dissertation lays the groundwork for more efficient algal disruption through the judicious use of microbubbles. Separation of bubble generation and bubble growth provides the ability to improve the efficiency of each process and localize energy. Results suggest that effective disruption can occur by pulsing high-pressure ultrasound waves to a solution of cells co-suspended with microbubbles. The models are thought to represent basic phenomenological mechanisms of disruption that could be exploited to improve the overall energy efficiency of schemes. Analysis suggests that extensional flow alone cannot be the cause of cell disruption near an expanding microbubble. Additionally, this work provides an estimate of the areal strain required disrupt an algal cell membrane. This research suggests a couple routes toward reducing the energy required for production of algal biodiesel.

ASSESSING THE VULNERABILITY OF AQUIFERS USING REGULARIZED POINT DATA.

EPA Science Inventory

The approach will be to collect available data on concentrations of dissolved nitrate. The data will be areally-averaged using covariance functions as Bras and Rodriguez-Iturbe (1993) described for the averaging of rainfall data. Polygon coverages of nitrate will be defined bas...

Investigation of the relation between the return periods of major drought characteristics using copula functions

NASA Astrophysics Data System (ADS)

Hüsami Afşar, Mehdi; Unal Şorman, Ali; Tugrul Yilmaz, Mustafa

2016-04-01

Different drought characteristics (e.g. duration, average severity, and average areal extent) often have monotonic relation that increased magnitude of one often follows a similar increase in the magnitude of the other drought characteristic. Hence it is viable to establish a relationship between different drought characteristics with the goal of predicting one using other ones. Copula functions that relate different variables using their joint and conditional cumulative probability distributions are often used to statistically model the drought characteristics. In this study bivariate and trivariate joint probabilities of these characteristics are obtained over Ankara (Turkey) between 1960 and 2013. Copula-based return period estimation of drought characteristics of duration, average severity, and average areal extent show joint probabilities of these characteristics can be satisfactorily achieved. Among different copula families investigated in this study, elliptical family (i.e. including normal and t-student copula functions) resulted in the lowest root mean square error. "This study was supported by TUBITAK fund #114Y676)."

Variations in lake and reservoir storage associated with Middle East droughts

NASA Astrophysics Data System (ADS)

Marlier, M. E.; Kim, J.; Khandelwal, A.; Karpatne, A.; Kumar, V.; Zhou, T.; Lettenmaier, D. P.

2016-12-01

The Middle East experienced severe drought conditions from 1998-2000 and again from 2007-2009; during both periods cumulative monthly precipitation averaged over the Fertile Crescent fell below the 10th percentile of the 1940-2009 climatology. The severity of the drought has been linked to rising greenhouse gas concentrations and may have contributed to the conflict in Syria. We use multiple sources of satellite data to examine how these droughts impacted surface water storage in Turkey, Syria, Iran, and Iraq. We first apply a MODIS-based classification algorithm to map variations in the areal extent of lakes and reservoirs from 2000-2015 at 500 m spatial resolution and nominal eight-day intervals. We combine this information with estimates of changes in water levels from several archives of radar altimetry products (Global Reservoir and Lake Monitor (G-REALM), Database for Hydrological Time Series of Inland Waters (DAHITI), and HydroWeb) for 16 lakes and reservoirs across the region at 10-day and/or 35-day intervals, and then estimate storage variations as far back as the 1990s. We find strong correlations between surface areal extent and water level variations, with preliminary results for reservoirs ranging from R=0.30-0.98 (median R=0.84). Taken together, we use this information to explore variations in temporal trends in water storage across the region.

Large areal mass, flexible and free-standing reduced graphene oxide/manganese dioxide paper for asymmetric supercapacitor device.

PubMed

Sumboja, Afriyanti; Foo, Ce Yao; Wang, Xu; Lee, Pooi See

2013-05-28

Well-separated RGO sheets decorated with MnO2 nanoparticles facilitate easy access of the electrolyte ions to the high surface area of the paper electrode, enabling the fabrication of a thicker electrode with heavier areal mass and higher areal capacitance (up to 897 mF cm(-2) ). The electrochemical performance of the bent asymmetric device with a total active mass of 15 mg remains similar to the one in the flat configuration, demonstrating good mechanical robustness of the device. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Feature-based characterisation of signature topography in laser powder bed fusion of metals

NASA Astrophysics Data System (ADS)

Senin, Nicola; Thompson, Adam; Leach, Richard

2018-04-01

The use of state-of-the-art areal topography measurement instrumentation allows for a high level of detail in the acquisition of topographic information at micrometric scales. The 3D geometric models of surface topography obtained from measured data create new opportunities for the investigation of manufacturing processes through characterisation of the surfaces of manufactured parts. Conventional methods for quantitative assessment of topography usually only involve the computation of texture parameters, summary indicators of topography-related characteristics that are computed over the investigated area. However, further useful information may be obtained through characterisation of signature topographic formations, as more direct indicators of manufacturing process behaviour and performance. In this work, laser powder bed fusion of metals is considered. An original algorithmic method is proposed to isolate relevant topographic formations and to quantify their dimensional and geometric properties, using areal topography data acquired by state-of-the-art areal topography measurement instrumentation.

Observed impacts of wind farms on land surface temperature in Inner Mongolia

NASA Astrophysics Data System (ADS)

Tang, B.; Zhao, X.; Wu, D.; Zhao, W.; Wei, H.

2015-12-01

Abstract: The wind turbine industry in china has experienced a dramatic increase in recent years and wind farms (WFs) have an impact on the underlying surface conditions of climate system. This paper assesses the impacts of wind farms by analyzing the variations of the land surface temperature (LST) data for the period of 2003-2014 over a region consisted of 1097 turbines in the Huitengxile Wind Farm, the largest wind farm in Asia. We first compare the spatial coupling between the geographic layouts of the WFs and the spatial patterns of LST changes of two periods (post- versus pre- wind turbines construction) and then employ the difference of LST between WF pixels and surrounding non-WF pixels to quantify the effects of WFs. The results reveal that the LST at daytime increases by 0.52-0.86°C in winter, spring and autumn and decreases by about 0.56°C in summer over the WFs on average, with the spatial pattern of this warming or cooling generally coupled with the geographic distribution of the wind turbines, while the changes in LST at nighttime are much noisier. The daytime LST warming or cooling effects vary with seasons, and the strongest warming and tightest spatial coupling are in autumn months of September-November. The seasonal variations in albedo due to the construction of wind turbines are primarily responsible for the daytime LST changes. Areal mean decreases in winter, spring and autumn and increase in summer in albedo are observed over the WFs and the spatial pattern and magnitude of the changes in albedo couple very well with the layouts of the wind turbines. The increase (decrease) in albedo over the WFs indicates that WFs across the Huitengxile grassland absorb less (more) incoming radiation, thus resulting in a decrease (increase) in LST at daytime. The inter-annual variations in areal mean LST differences at daytime are highly correlated with those in areal mean albedo differences for all four seasons (R2=0.48~0.67). Our findings are in contrast with those studies, which show a warming effect at nighttime and no apparent effect on LST at daytime over the WFs in the United States. Keywords: Wind farm impacts; land surface temperature; albedo; warming and cooling

Dynamic comparisons of piezoelectric ejecta diagnostics

NASA Astrophysics Data System (ADS)

Buttler, W. T.; Zellner, M. B.; Olson, R. T.; Rigg, P. A.; Hixson, R. S.; Hammerberg, J. E.; Obst, A. W.; Payton, J. R.; Iverson, A.; Young, J.

2007-03-01

We investigate the quantitative reliability and precision of three different piezoelectric technologies for measuring ejected areal mass from shocked surfaces. Specifically we performed ejecta measurements on Sn shocked at two pressures, P ≈215 and 235 kbar. The shock in the Sn was created by launching a impactor with a powder gun. We self-compare and cross-compare these measurements to assess the ability of these probes to precisely determine the areal mass ejected from a shocked surface. We demonstrate the precision of each technology to be good, with variabilities on the order of ±10%. We also discuss their relative accuracy.

Nike Experiment to Observe Strong Areal Mass Oscillations in a Rippled Target Hit by a Short Laser Pulse

NASA Astrophysics Data System (ADS)

Aglitskiy, Y.; Karasik, M.; Velikovich, A. L.; Serlin, V.; Weaver, J. L.; Kessler, T. J.; Schmitt, A. J.; Obenschain, S. P.; Metzler, N.; Oh, J.

2010-11-01

When a short (sub-ns) laser pulse deposits finite energy in a target, the shock wave launched into it is immediately followed by a rarefaction wave. If the irradiated surface is rippled, theory and simulations predict strong oscillations of the areal mass perturbation amplitude in the target [A. L. Velikovich et al., Phys. Plasmas 10, 3270 (2003).] The first experiment designed to observe this effect has become possible by adding short-driving-pulse capability to the Nike laser, and has been scheduled for the fall of 2010. Simulations show that while the driving pulse of 0.3 ns is on, the areal mass perturbation amplitude grows by a factor ˜2 due to ablative Richtmyer-Meshkov instability. It then decreases, reverses phase, and reaches another maximum, also about twice its initial value, shortly after the shock breakout at the rear target surface. This signature behavior is observable with the monochromatic x-ray imaging diagnostics fielded on Nike.

Estimation of effective hydrologic properties of soils from observations of vegetation density. M.S. Thesis; [water balance of watersheds in Clinton, Maine and Santa Paula, California

NASA Technical Reports Server (NTRS)

Tellers, T. E.

1980-01-01

An existing one-dimensional model of the annual water balance is reviewed. Slight improvements are made in the method of calculating the bare soil component of evaporation, and in the way surface retention is handled. A natural selection hypothesis, which specifies the equilibrium vegetation density for a given, water limited, climate-soil system, is verified through comparisons with observed data and is employed in the annual water balance of watersheds in Clinton, Ma., and Santa Paula, Ca., to estimate effective areal average soil properties. Comparison of CDF's of annual basin yield derived using these soil properties with observed CDF's provides excellent verification of the soil-selection procedure. This method of parameterization of the land surface should be useful with present global circulation models, enabling them to account for both the non-linearity in the relationship between soil moisture flux and soil moisture concentration, and the variability of soil properties from place to place over the Earth's surface.

Mapping Human Cortical Areas in vivo Based on Myelin Content as Revealed by T1- and T2-weighted MRI

PubMed Central

Glasser, Matthew F.; Van Essen, David C.

2011-01-01

Non-invasively mapping the layout of cortical areas in humans is a continuing challenge for neuroscience. We present a new method of mapping cortical areas based on myelin content as revealed by T1-weighted (T1w) and T2-weighted (T2w) MRI. The method is generalizable across different 3T scanners and pulse sequences. We use the ratio of T1w/T2w image intensities to eliminate the MR-related image intensity bias and enhance the contrast to noise ratio for myelin. Data from each subject was mapped to the cortical surface and aligned across individuals using surface-based registration. The spatial gradient of the group average myelin map provides an observer-independent measure of sharp transitions in myelin content across the surface—i.e. putative cortical areal borders. We found excellent agreement between the gradients of the myelin maps and the gradients of published probabilistic cytoarchitectonically defined cortical areas that were registered to the same surface-based atlas. For other cortical regions, we used published anatomical and functional information to make putative identifications of dozens of cortical areas or candidate areas. In general, primary and early unimodal association cortices are heavily myelinated and higher, multi-modal, association cortices are more lightly myelinated, but there are notable exceptions in the literature that are confirmed by our results. The overall pattern in the myelin maps also has important correlations with the developmental onset of subcortical white matter myelination, evolutionary cortical areal expansion in humans compared to macaques, postnatal cortical expansion in humans, and maps of neuronal density in non-human primates. PMID:21832190

Reconnoitering the effect of shallow groundwater on land surface temperature and surface energy balance using MODIS and SEBS

USDA-ARS?s Scientific Manuscript database

The possibility of observing shallow groundwater depth and areal extent using satellite measurements can support groundwater models and vast irrigation systems management. Besides, these measurements help to integrate groundwater effects on surface energy balance within land surface models and clima...

First status report on regional ground-water flow modeling for the Paradox Basin, Utah

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

Andrews, R.W.

1984-05-01

Regional ground-water flow within the principal hydrogeologic units of the Paradox Basin is evaluated by developing a conceptual model of the flow regime in the shallow aquifers and the deep-basin brine aquifers and testing these models using a three-dimensional, finite-difference flow code. Semiquantitative sensitivity analysis (a limited parametric study) is conducted to define the system response to changes in hydrologic properties or boundary conditions. A direct method for sensitivity analysis using an adjoint form of the flow equation is applied to the conceptualized flow regime in the Leadville limestone aquifer. All steps leading to the final results and conclusions aremore » incorporated in this report. The available data utilized in this study is summarized. The specific conceptual models, defining the areal and vertical averaging of litho-logic units, aquifer properties, fluid properties, and hydrologic boundary conditions, are described in detail. Two models were evaluated in this study: a regional model encompassing the hydrogeologic units above and below the Paradox Formation/Hermosa Group and a refined scale model which incorporated only the post Paradox strata. The results are delineated by the simulated potentiometric surfaces and tables summarizing areal and vertical boundary fluxes, Darcy velocities at specific points, and ground-water travel paths. Results from the adjoint sensitivity analysis include importance functions and sensitivity coefficients, using heads or the average Darcy velocities to represent system response. The reported work is the first stage of an ongoing evaluation of the Gibson Dome area within the Paradox Basin as a potential repository for high-level radioactive wastes.« less

Microwave Assisted Synthesis of Porous NiCo2O4 Microspheres: Application as High Performance Asymmetric and Symmetric Supercapacitors with Large Areal Capacitance

PubMed Central

Khalid, Syed; Cao, Chuanbao; Wang, Lin; Zhu, Youqi

2016-01-01

Large areal capacitance is essentially required to integrate the energy storage devices at the microscale electronic appliances. Energy storage devices based on metal oxides are mostly fabricated with low mass loading per unit area which demonstrated low areal capacitance. It is still a challenge to fabricate supercapacitor devices of porous metal oxides with large areal capacitance. Herein we report microwave method followed by a pyrolysis of the as-prepared precursor is used to synthesize porous nickel cobaltite microspheres. Porous NiCo2O4 microspheres are capable to deliver large areal capacitance due to their high specific surface area and small crystallite size. The facile strategy is successfully demonstrated to fabricate aqueous-based asymmetric & symmetric supercapacitor devices of porous NiCo2O4 microspheres with high mass loading of electroactive materials. The asymmetric & symmetric devices exhibit maximum areal capacitance and energy density of 380 mF cm−2 & 19.1 Wh Kg−1 and 194 mF cm−2 & 4.5 Wh Kg−1 (based on total mass loading of 6.25 & 6.0 mg) respectively at current density of 1 mA cm−2. The successful fabrication of symmetric device also indicates that NiCo2O4 can also be used as the negative electrode material for futuristic asymmetric devices. PMID:26936283

Microwave Assisted Synthesis of Porous NiCo2O4 Microspheres: Application as High Performance Asymmetric and Symmetric Supercapacitors with Large Areal Capacitance

NASA Astrophysics Data System (ADS)

Khalid, Syed; Cao, Chuanbao; Wang, Lin; Zhu, Youqi

2016-03-01

Large areal capacitance is essentially required to integrate the energy storage devices at the microscale electronic appliances. Energy storage devices based on metal oxides are mostly fabricated with low mass loading per unit area which demonstrated low areal capacitance. It is still a challenge to fabricate supercapacitor devices of porous metal oxides with large areal capacitance. Herein we report microwave method followed by a pyrolysis of the as-prepared precursor is used to synthesize porous nickel cobaltite microspheres. Porous NiCo2O4 microspheres are capable to deliver large areal capacitance due to their high specific surface area and small crystallite size. The facile strategy is successfully demonstrated to fabricate aqueous-based asymmetric & symmetric supercapacitor devices of porous NiCo2O4 microspheres with high mass loading of electroactive materials. The asymmetric & symmetric devices exhibit maximum areal capacitance and energy density of 380 mF cm-2 & 19.1 Wh Kg-1 and 194 mF cm-2 & 4.5 Wh Kg-1 (based on total mass loading of 6.25 & 6.0 mg) respectively at current density of 1 mA cm-2. The successful fabrication of symmetric device also indicates that NiCo2O4 can also be used as the negative electrode material for futuristic asymmetric devices.

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.

Google Earth Engine derived areal extents to infer elevation variation of lakes and reservoirs

NASA Astrophysics Data System (ADS)

Nguy-Robertson, Anthony; May, Jack; Dartevelle, Sebastien; Griffin, Sean; Miller, Justin; Tetrault, Robert; Birkett, Charon; Lucero, Eileen; Russo, Tess; Zentner, Matthew

2017-04-01

Monitoring water supplies is important for identifying potential national security issues before they begin. As a means to estimate lake and reservoir storage for sites without reliable water stage data, this study defines correlations between water body levels from hypsometry curves based on in situ gauge station and altimeter data (i.e. TOPEX/Poseidon, Jason series) and sensor areal extents observed in historic multispectral (i.e. MODIS and Landsat TM/ETM+/OLI) imagery. Water levels measured using in situ observations and altimeters, when in situ data were unavailable, were used to estimate the relationship between water elevation and surface area for 18 sites globally. Altimeters were generally more accurate (RMSE: 0.40 - 0.49 m) for estimating in situ lake elevations from Iraq and Afghanistan than the modeled elevation data using multispectral sensor areal extents: Landsat (RMSE: 0.25 - 1.5 m) and MODIS (RMSE 0.53 - 3.0 m). Correlations between altimeter data and Landsat imagery processed with Google Earth Engine confirmed similar relationships exists for a broader range of lakes without reported in situ data across the globe (RMSE: 0.24 - 1.6 m). Thus, while altimetry is still preferred to an areal extent model, lake surface area derived with Google Earth Engine can be used as a reasonable proxy for lake storage, expanding the number of observable lakes beyond the current constellation of altimeters and in situ gauges.

Dry-Processed, Binder-Free Holey Graphene Electrodes for Supercapacitors with Ultrahigh Areal Loadings.

PubMed

Walsh, Evan D; Han, Xiaogang; Lacey, Steven D; Kim, Jae-Woo; Connell, John W; Hu, Liangbing; Lin, Yi

2016-11-02

For commercial applications, the need for smaller footprint energy storage devices requires more energy to be stored per unit area. Carbon nanomaterials, especially graphene, have been studied as supercapacitor electrodes and can achieve high gravimetric capacities affording high gravimetric energy densities. However, most nanocarbon-based electrodes exhibit a significant decrease in their areal capacitances when scaled to the high mass loadings typically used in commercially available cells (∼10 mg/cm 2 ). One of the reasons for this behavior is that the additional surface area in thick electrodes is not readily accessible by electrolyte ions due to the large tortuosity. Furthermore, the fabrication of such electrodes often involves complicated processes that limit the potential for mass production. Here, holey graphene electrodes for supercapacitors that are scalable in both production and areal capacitance are presented. The lateral surface porosity on the graphene sheets was created using a facile single-step air oxidation method, and the resultant holey graphene was compacted under ambient conditions into mechanically robust monolithic shapes that can be directly used as binder-free electrodes. In comparison, pristine graphene discs under similar binder-free compression molding conditions were extremely brittle and thus not deemed useful for electrode applications. The coin cell supercapacitors, based on these holey graphene electrodes exhibited small variations in gravimetric capacitance over a wide range of areal mass loadings (∼1-30 mg/cm 2 ) at current densities as high as 30 mA/cm 2 , resulting in the near-linear increase of the areal capacitance (F/cm 2 ) with the mass loading. The prospects of the presented method for facile binder-free ultrathick graphene electrode fabrication are discussed.

Geographic, geologic, and hydrologic summaries of intermontane basins of the northern Rocky Mountains, Montana

USGS Publications Warehouse

Kendy, Eloise; Tresch, R.E.

1996-01-01

This report combines a literature review with new information to provide summaries of the geography, geology, and hydrology of each of 32 intermontane basins in western Montana. The summary of each intermontane basin includes concise descriptions of topography, areal extent, altitude, climate, 1990 population, land and water use, geology, surface water, aquifer hydraulic characteristics, ground-water flow, and ground-water quality. If present, geothermal features are described. Average annual and monthly temperature and precipitation are reported from one National Weather Service station in each basin. Streamflow data, including the drainage area, period of record, and average, minimum, and maximum historical streamflow, are reported for all active and discontinued USGS streamflow-gaging stations in each basin. Monitoring-well data, including the well depth, aquifer, period of record, and minimum and maximum historical water levels, are reported for all long-term USGS monitoring wells in each basin. Brief descriptions of geologic, geophysical, and potentiometric- surface maps available for each basin also are included. The summary for each basin also includes a bibliography of hydrogeologic literature. When used alone or in conjunction with regional RASA reports, this report provides a practical starting point for site-specific hydrogeologic investigations.

Some relations between streamflow characteristics and the environment in the Delaware River region

USGS Publications Warehouse

Hely, A.G.; Olmsted, F.H.

1963-01-01

Streamflow characteristics are determined by a large number of factors of the meteorological and terrestrial environments. Because of lack of quantitative data to describe some of the factors and complex interrelations among them, complete analysis of the relations between streamflow and the various environmental factors is impossible. However, certain simplifying assumptions and generalizations made possible a partial analysis for the Delaware River region. For relations involving average runoff or low-flow parameters, average annual precipitation was assumed to be the principal meteorological factor, and geology (a complex of many factors) was assumed to be the principal terrestrial influence, except for that of basin size which was largely eliminated by expression of discharge in terms of unit area. As a first approximation, physiographic units were used as a basis for classifying the geology. Relations between flow parameters and precipitation are fairly well defined for some physiographic units, but not for those in which the geology varies markedly or the areal variation in average precipitation is very small. These relations provide a basis for adjusting the flow parameters to reduce or eliminate the effects of areal variations in precipitation and increase their significance in studies of the effects of terrestrial characteristics. An investigation of the residual effect of basin size (the effect remaining when discharge is expressed in terms of unit area) on relations between flow parameters and average precipitation indicates that such effect is negligible, except for very large differences in area. Parameters that are derived from base-flow recession curves and are related to a common discharge per unit area have inherent advantages as indicators of effects of terrestrial characteristics of basins, because the.y are independent of areal variations in average annual precipitation. Winter base-flow parameters are also practically independent of the effects of evapotranspiration from ground water. However, in many parts of the region these advantages are reduced or nullified by the difficulties of defining base-flow recession curves, particularly winter curves, with sufficient accuracy. In the absence of suitable base-flow recession data and a suitable basis for adjusting parameters, the ratio of the discharge equaled or exceeded 90 percent of the time to the average discharge (Qtt/Qa), or a similar duration parameter, probably is the best indicator of the influence of terrestrial characteristics, although the ratio may vary somewhat with average precipitation. In a part of the region where geologic differences are large and areal variations in average precipitation are small, values of Qm/Qa for each major geologic unit were determined from streamflow records. From these values and the percentage of area represented by each unit, a ratio for each gaging station was computed. Comparison of these computed results with the observed results indicates that nearly all of the variation in the ratio is associated with variation in geology. The investigation indicates that the original assumptions are correct; average precipitation is the principal meteorological influence and geology is the principal terrestrial influence. Together these two factors account for a very large proportion of the variation in average runoff and low-flow characteristics

High-performance all-solid-state flexible supercapacitors based on two-step activated carbon cloth

NASA Astrophysics Data System (ADS)

Jiang, Shulan; Shi, Tielin; Zhan, Xiaobin; Long, Hu; Xi, Shuang; Hu, Hao; Tang, Zirong

2014-12-01

A simple and effective strategy is proposed to activate carbon cloth for the fabrication of flexible and high-performance supercapacitors. Firstly, the carbon cloth surface is exfoliated as nanotextures through wet chemical treatment, then an annealing process is applied at H2/N2 atmosphere to reduce the surface oxygen functional groups which are mainly introduced from the first step. The activated carbon cloth electrode shows excellent wettablity, large surface area and delivers remarkable electrochemical performance. A maximum areal capacitance of 485.64 mF cm-2 at the current density of 2 mA cm-2 is achieved for the activated carbon cloth electrode, which is considerably larger than the resported results for carbon cloth. Furthermore, the flexible all-solid-state supercapacitor, which is fabricated based on the activated carbon cloth electrodes, shows high areal capacitance, superior cycling stability as well as stable electrochemical performance even under constant bending or twisting conditions. An areal capacitance of 161.28 mF cm-2 is achieved at the current density of 12.5 mA cm-2, and 104% of its initial capacitance is retained after 30,000 charging/discharging cycles. This study would also provide an effective way to boost devices' electrochemical performance by accommodating other active materials on the activated carbon cloth.

Deep Impact: Effects of Mountaintop Mining on Surface Topography, Bedrock Structure, and Downstream Waters.

PubMed

Ross, Matthew R V; McGlynn, Brian L; Bernhardt, Emily S

2016-02-16

Land use impacts are commonly quantified and compared using 2D maps, limiting the scale of their reported impacts to surface area estimates. Yet, nearly all land use involves disturbances below the land surface. Incorporating this third dimension into our estimates of land use impact is especially important when examining the impacts of mining. Mountaintop mining is the most common form of coal mining in the Central Appalachian ecoregion. Previous estimates suggest that active, reclaimed, or abandoned mountaintop mines cover ∼7% of Central Appalachia. While this is double the areal extent of development in the ecoregion (estimated to occupy <3% of the land area), the impacts are far more extensive than areal estimates alone can convey as the impacts of mines extend 10s to 100s of meters below the current land surface. Here, we provide the first estimates for the total volumetric and topographic disturbance associated with mining in an 11 500 km(2) region of southern West Virginia. We find that the cutting of ridges and filling of valleys has lowered the median slope of mined landscapes in the region by nearly 10 degrees while increasing their average elevation by 3 m as a result of expansive valley filling. We estimate that in southern West Virginia, more than 6.4km(3) of bedrock has been broken apart and deposited into 1544 headwater valley fills. We used NPDES monitoring datatsets available for 91 of these valley fills to explore whether fill characteristics could explain variation in the pH or selenium concentrations reported for streams draining these fills. We found that the volume of overburden in individual valley fills correlates with stream pH and selenium concentration, and suggest that a three-dimensional assessment of mountaintop mining impacts is necessary to predict both the severity and the longevity of the resulting environmental impacts.

Comparison of large crater and multiringed basin populations on Mars, Mercury, and the moon

NASA Technical Reports Server (NTRS)

Malin, M. C.

1976-01-01

The maximum regional areal densities of large impact craters on Mars, Mercury, and the moon appear to be inversely proportional to the surface areas of the planets. This would not be expected if the objects impacting the planetary surfaces came from common sources and were moving with high velocities relative to the planets; rather, a uniform areal density would be anticipated. Another way of stating the observation is that each planet was bombarded by the same number of objects. Two speculative explanations for the observation are that: (1) all planets underwent a uniform bombardment but were resurfaced by processes proportional to planetary surface area, or (2) equally populated families of objects, moving about the sun in orbits similar to those of the planets, were independently depopulated by the respective planets.

Tips pentacene crystal alignment for improving performance of solution processed organic thin film transistors

NASA Astrophysics Data System (ADS)

He, Zhengran

A newly-developed p-type organic semiconductor 6,13-bis (triisopropylsilylethynyl) pentacene (TIPS pentacene) demonstrates various advantages such as high mobility, air stability and solution processibility, but at the same time its application is restricted by major issues, such as crystal misorientation and performance variation of organic thin-film transistors (OTFTs). This dissertation demonstrates several different approaches to address these issues. As a result, both crystal orientation and areal coverage can be effectively improved, leading to an enhancement of average mobility and performance consistency of OTFTs. Chapter 1 presents an introduction and background of this dissertation. Chapter 2 explores the usage of inorganic silica nanoparticles to manipulate the morphology of TIPS pentacene thin films and the performance of solution-processed organic OTFTs. The resultant drop-cast films yield improved morphological uniformity at ~10% SiO2 loading, which also leads to a 3-fold increase in average mobility and nearly 4-times reduction in the ratio of standard deviation of mobility (μStdev) to average mobility (μAvg). The experimental results suggest that the SiO2 nanoparticles mostly aggregate at TIPS pentacene grain boundaries, and that 10% nanoparticle concentration effectively reduces the undesirable crystal misorientation without considerably compromising TIPS pentacene crystallinity. Chapter 3 discusses the utilization of air flow to effectively reduce the TIPS pentacene crystal anisotropy and enhance performance consistency in OTFTs. Under air-flow navigation (AFN), TIPS pentacene forms thin films with improved crystal orientation and increased areal coverage, which subsequently lead to a four-fold increase of average hole mobility and one order of magnitude enhancement in performance consistency. Chapter 4 investigates the critical roles of lateral and vertical phase separation in the performance of the next-generation organic and hybrid electronic devices. A novel method is demonstrated here to switch between lateral and vertical phase separation in semiconducting TIPS pentacene/ polymer blend films by simply varying the alkyl length of the polyacrylate polymer component. The phase separation modes depend on intermolecular interactions between small molecule TIPS pentacene and polymer additives. The blend film with a dominant vertical phase separation exhibits a significant enhancement in average mobility and performance consistency of organic OTFTs. Chapter 5 demonstrates an effective approach to improve both charge transport and performance consistency in solution-processed OTFTs by blending TIPS pentacene with a series of small-molecule additives: 4-butylbenzoic acid (BBA), 4-hexylbenzoic acid (HBA), and 4-octylbenzoic acid (OBA). These three small molecules share a benzoic acid moiety, but have different length of hydrophobic tails. The self-assembled interfacial layer of small molecules on the gate oxide surface leads to uniform deposition of TIPS pentacene crystal seeds and facilitates TIPS pentacene to grow along the tilted orientation of substrate, which results in a film of enhanced crystal orientation and areal coverage. OTFTs based on TIPS pentacene/small molecule blends demonstrate greatly improved average hole mobility and performance consistency, which correlates with the length of hydrophobic tail of the small-molecule additives. Chapter 6 summarizes the conclusions of this dissertation and the related future work.

Simulations and experiments of the growth of the “tent” perturbation in NIF ignition implosions

NASA Astrophysics Data System (ADS)

Hammel, B. A.; Tommasini, R.; Clark, D. S.; Field, J.; Stadermann, M.; Weber, C.

2016-05-01

NIF capsules are supported in the hohlraum by two thin (∼15-110 nm) Formvar films (“tent”). Highly resolved HYDRA simulations indicate that a large (∼40% peak-average) areal density (ρR) perturbation develops on the capsule during acceleration as a consequence of this support geometry. This perturbation results in a jet of dense DT and, in some cases, CH that penetrates and cools the hot spot, significantly degrading the neutron yield (∼10-20% of 1D yield). We examine “low-foot” and “high-foot” pulse shapes, tent thicknesses, and geometries. Simulations indicate that thinner tents result in a smaller pR perturbation, however, the departure angle of the tent from the capsule surface is important, with steeper angles resulting in larger perturbations.

Using environmental heterogeneity to plan for sea-level rise.

PubMed

Hunter, Elizabeth A; Nibbelink, Nathan P

2017-12-01

Environmental heterogeneity is increasingly being used to select conservation areas that will provide for future biodiversity under a variety of climate scenarios. This approach, termed conserving nature's stage (CNS), assumes environmental features respond to climate change more slowly than biological communities, but will CNS be effective if the stage were to change as rapidly as the climate? We tested the effectiveness of using CNS to select sites in salt marshes for conservation in coastal Georgia (U.S.A.), where environmental features will change rapidly as sea level rises. We calculated species diversity based on distributions of 7 bird species with a variety of niches in Georgia salt marshes. Environmental heterogeneity was assessed across six landscape gradients (e.g., elevation, salinity, and patch area). We used 2 approaches to select sites with high environmental heterogeneity: site complementarity (environmental diversity [ED]) and local environmental heterogeneity (environmental richness [ER]). Sites selected based on ER predicted present-day species diversity better than randomly selected sites (up to an 8.1% improvement), were resilient to areal loss from SLR (1.0% average areal loss by 2050 compared with 0.9% loss of randomly selected sites), and provided habitat to a threatened species (0.63 average occupancy compared with 0.6 average occupancy of randomly selected sites). Sites selected based on ED predicted species diversity no better or worse than random and were not resilient to SLR (2.9% average areal loss by 2050). Despite the discrepancy between the 2 approaches, CNS is a viable strategy for conservation site selection in salt marshes because the ER approach was successful. It has potential for application in other coastal areas where SLR will affect environmental features, but its performance may depend on the magnitude of geological changes caused by SLR. Our results indicate that conservation planners that had heretofore excluded low-lying coasts from CNS planning could include coastal ecosystems in regional conservation strategies. © 2017 Society for Conservation Biology.

Method to grow pure nanocrystalline diamond films at low temperatures and high deposition rates

DOEpatents

Carlisle, John A [Plainfield, IL; Gruen, Dieter M [Downers Grove, IL; Auciello, Orlando [Bolingbrook, IL; Xiao, Xingcheng [Woodridge, IL

2009-07-07

A method of depositing nanocrystalline diamond film on a substrate at a rate of not less than about 0.2 microns/hour at a substrate temperature less than about 500.degree. C. The method includes seeding the substrate surface with nanocrystalline diamond powder to an areal density of not less than about 10.sup.10sites/cm.sup.2, and contacting the seeded substrate surface with a gas of about 99% by volume of an inert gas other than helium and about 1% by volume of methane or hydrogen and one or more of acetylene, fullerene and anthracene in the presence of a microwave induced plasma while maintaining the substrate temperature less than about 500.degree. C. to deposit nanocrystalline diamond on the seeded substrate surface at a rate not less than about 0.2 microns/hour. Coatings of nanocrystalline diamond with average particle diameters of less than about 20 nanometers can be deposited with thermal budgets of 500.degree. C.-4 hours or less onto a variety of substrates such as MEMS devices.

Relevance of ammonium oxidation within biological soil crust communities

USGS Publications Warehouse

Johnson, S.L.; Budinoff, C.R.; Belnap, J.; Garcia-Pichel, F.

2005-01-01

Thin, vertically structured topsoil communities that become ecologically important in arid regions (biological soil crusts or BSCs) are responsible for much of the nitrogen inputs into pristine arid lands. We studied N2 fixation and ammonium oxidation (AO) at subcentimetre resolution within BSCs from the Colorado Plateau. Pools of dissolved porewater nitrate/ nitrite, ammonium and organic nitrogen in wetted BSCs were high in comparison with those typical of aridosoils. They remained stable during incubations, indicating that input and output processes were of similar magnitude. Areal N2 fixation rates (6.5-48 ??mol C2H2 m-2 h -1) were high, the vertical distribution of N2 fixation peaking close to the surface if populations of heterocystous cyanobacteria were present, but in the subsurface if they were absent. Areal AO rates (19-46 ??mol N m-2 h-1) were commensurate with N2 fixation inputs. When considering oxygen availability, AO activity invariably peaked 2-3 mm deep and was limited by oxygen (not ammonium) supply. Most probable number (MPN)-enumerated ammonia-oxidizing bacteria (6.7-7.9 ?? 103 cells g-1 on average) clearly peaked at 2-3 mm depth. Thus, AO (hence nitrification) is a spatially restricted but important process in the nitrogen cycling of BSC, turning much of the biologically fixed nitrogen into oxidized forms, the fate of which remains to be determined.

Three-dimensional modeling of the neutron spectrum to infer plasma conditions in cryogenic inertial confinement fusion implosions

NASA Astrophysics Data System (ADS)

Weilacher, F.; Radha, P. B.; Forrest, C.

2018-04-01

Neutron-based diagnostics are typically used to infer compressed core conditions such as areal density and ion temperature in deuterium-tritium (D-T) inertial confinement fusion (ICF) implosions. Asymmetries in the observed neutron-related quantities are important to understanding failure modes in these implosions. Neutrons from fusion reactions and their subsequent interactions including elastic scattering and neutron-induced deuteron breakup reactions are tracked to create spectra. It is shown that background subtraction is important for inferring areal density from backscattered neutrons and is less important for the forward-scattered neutrons. A three-dimensional hydrodynamic simulation of a cryogenic implosion on the OMEGA Laser System [Boehly et al., Opt. Commun. 133, 495 (1997)] using the hydrodynamic code HYDRA [Marinak et al., Phys. Plasmas 8, 2275 (2001)] is post-processed using the tracking code IRIS3D. It is shown that different parts of the neutron spectrum from the view can be mapped into different regions of the implosion, enabling an inference of an areal-density map. It is also shown that the average areal-density and an areal-density map of the compressed target can be reconstructed with a finite number of detectors placed around the target chamber. Ion temperatures are inferred from the width of the D-D and D-T fusion neutron spectra. Backgrounds can significantly alter the inferred ion temperatures from the D-D reaction, whereas they insignificantly influence the inferred D-T ion temperatures for the areal densities typical of OMEGA implosions. Asymmetries resulting in fluid flow in the core are shown to influence the absolute inferred ion temperatures from both reactions, although relative inferred values continue to reflect the underlying asymmetry pattern. The work presented here is part of the wide range of the first set of studies performed with IRIS3D. This code will continue to be used for post-processing detailed hydrodynamic simulations and interpreting observed neutron spectra in ICF implosions.

Annual Nutrient Loadings, Primary Productivity, and Trophic State of Lake Koocanusa, Montana and British Columbia, 1972-80

USGS Publications Warehouse

Woods, Paul F.

1982-01-01

Limnological data collected at Lake Koocanusa were used to investigate the relationship of nutrient loadings, primary productivity, and trophic state of the reservoir during 1972-80. The reservoir, on the Kootenai River, was impounded by Libby Dam on March 21, 1972. Manipulation of the 7.16-cubic-kilometer reservoir for flood control, its primary function, created large fluctuations in reservoir volume and produced annual lake-filling times that ranged from 0.14 to 0.66 year. Loadings of nitrogen and phosphorus prior to and following impoundment of Lake Koocanusa were found to be large enough to predict eutrophic conditions. Beginning in 1976, total phosphorus loadings, but not total nitrogen loadings, were substantially reduced following improvements in waste-water treatment at a fertilizer plant located upstream from the reservoir. The closure of Libby Dam substantially reduced loadings of nitrogen and phosphorus downstream from Lake Koocanusa. On the average, the reservoir retained 63 percent of its influent loading of total phosphorus and 25 percent of its influent loading of total nitrogen. Daily areal and volumetric primary productivity varied widely in each year at four sampled limnological stations. During the 9 years studied, daily areal primary productivity, in milligrams of carbon fixed per square meter, ranged from 0.4 to 420.0; the mean of the 313 sampled days was 128.5. Annual areal primary productivity ranged from 23.2 to 38.5 grams of carbon fixed per square meter and thereby categorized Lake Koocanusa as oligotrophic. The relationship of annual areal primary productivity and 12 selected environmental variables was determined by multiple regression analysis. One of the models that was derived used two variables-annual euphotic zone depth and annual areal phosphorus loading-and accounted for 62.0 percent of the variation in annual areal primary productivity. The distribution of chlorophyll a within the water column indicated that, on the average, more than one-half of the phytoplankton in the reservoir was beneath the euphotic zone. These results support the hypothesis that the reservoir's weak thermal structure had allowed circulation of phytoplankton out of the euphotic zone. The trophic state of Lake Koocanusa was categorized as eutrophic when based on the relationship of the nutrient loadings and the reservoir's ratio of mean depth to hydraulic-residence time. This result conflicted with the oligotrophic ranking the reservoir received based on its areal primary productivity. The discrepancy in trophic state was attributed mainly to the failure of nutrient loading models to adequately account for physical processes within reservoirs. Part of the nutrient loading that entered Lake Koocanusa was unavailable to phytoplankton because the nutrients were carried beneath the euphotic zone by large volumes of interflow and underflow. Another part of the nutrient loading was adsorbed to suspended sediment and removed from the water column. Thus, phytoplankton primary productivity was controlled not only by nutrients, but also by other limno logical processes.

SUBMERSED MACROPHYTE DISTRIBUTION AND FUNCTION IN THE TIDAL FRESHWATER HUDSON RIVER

EPA Science Inventory

In the tidal freshwater Hudson River submerged aquatic vegetation (SAV) occupies on average 6 percent of the river area with much greater coverage in the mid Hudson (Kingston-Hudson) and much lower areal coverage south of Hyde Park. The native water celery ( Vallisneria americana...

Remotely sensed MODIS wetland components for assessing the variability of methane emissions in Indian tropical/subtropical wetlands

NASA Astrophysics Data System (ADS)

Bansal, Sangeeta; Katyal, Deeksha; Saluja, Ridhi; Chakraborty, Monojit; Garg, J. K.

2018-02-01

Temperature and area fluctuations in wetlands greatly influence its various physico-chemical characteristics, nutrients dynamic, rates of biomass generation and decomposition, floral and faunal composition which in turn influence methane (CH4) emission rates. In view of this, the present study attempts to up-scale point CH4 flux from the wetlands of Uttar Pradesh (UP) by modifying two-factor empirical process based CH4 emission model for tropical wetlands by incorporating MODIS derived wetland components viz. wetland areal extent and corresponding temperature factors (Ft). This study further focuses on the utility of remotely sensed temperature response of CH4 emission in terms of Ft. Ft is generated using MODIS land surface temperature products and provides an important semi-empirical input for up-scaling CH4 emissions in wetlands. Results reveal that annual mean Ft values for UP wetlands vary from 0.69 (2010-2011) to 0.71(2011-2012). The total estimated area-wise CH4 emissions from the wetlands of UP varies from 66.47 Gg yr-1with wetland areal extent and Ft value of 2564.04 km2 and 0.69 respectively in 2010-2011 to 88.39 Gg yr-1with wetland areal extent and Ft value of 2720.16 km2 and 0.71 respectively in 2011-2012. Temporal analysis of estimated CH4 emissions showed that in monsoon season estimated CH4 emissions are more sensitive to wetland areal extent while in summer season sensitivity of estimated CH4 emissions is chiefly controlled by augmented methanogenic activities at high wetland surface temperatures.

Climatology of the oceanography in the northern South China Sea Shelf-sea (NoSoCS) and adjacent waters: Observations from satellite remote sensing

NASA Astrophysics Data System (ADS)

Pan, X.; Wong, G. T.; Tai, J.; Ho, T.

2013-12-01

By using the observations from multiple satellite sensors, the climatology of the oceanography, including the surface wind vector, sea surface temperature (SST), surface chlorophyll a concentration (Chl_a), and vertically integrated net primary production (PPeu), in the northern South China Sea Shelf-sea (NoSoCS) and adjacent waters is evaluated. Regional and sub-regional mechanisms in driving the coastal processes, which influence the spatial and temporal distributional patterns in water component, are assessed. Seasonal vertical convective mixing by wind and surface heating/cooling is the primary force in driving the annual changes in SST and Chl_a in the open South China Sea (SCS), in which highly negative correlation coefficients between Chl_a and SST and moderately positive correlation coefficients between Chl_a and wind speed are found. Together, the seasonal variations in SST and wind speed account for about 80% of the seasonal variation in Chl_a. In the NoSoCS as a whole, however, the contribution is reduced to about 40%, primarily due to the effect of the Pearl River plume. A tongue of water extending eastward from the mouth of the River into the middle shelf with positive correlation coefficients between Chl_a and SST and around zero or slightly negative correlation coefficients between Chl_a and wind is the most striking feature in the NoSoCS. The westward and eastward propagations of the Pearl River plume are both very small during the northeast monsoonal season, driven primarily by the Coriolis effect. The abrupt increase in the areal coverage of the River plume, which is much more pronounced in the eastward propagation, between June and August can be attributed to the prevailing southwest monsoon as well as the annual peak of the river flow. Coastal upwelling is another sub-regional phenomenon in the NoSoCS. The upwelling at the shelf edge off the Taiwan Bank may be characterized by its elevated Chl_a. Its areal coverage and average Chl_a do not vary greatly from month to month. The upwelling off the Hainan Island during the southwest monsoonal season may be characterized by its depression in SST. Its areal coverage reaches the maximum in July. Quantitatively characterizing the upwelling off Dongshan during the southwest monsoonal season is difficult and is not attempted here. The sub-regional phenomenon, activities of internal waves off the shelf break, is also assessed. Internal waves can reach the entire outer shelf- upper slope of the NoSoCS where they undergo transformation and even destruction, resulting in the depression in SST and the enhancement in Chl_a. The effect is more pronounced north of the Dongsha Atoll.

Geostatistical analysis of disease data: accounting for spatial support and population density in the isopleth mapping of cancer mortality risk using area-to-point Poisson kriging

PubMed Central

Goovaerts, Pierre

2006-01-01

Background Geostatistical techniques that account for spatially varying population sizes and spatial patterns in the filtering of choropleth maps of cancer mortality were recently developed. Their implementation was facilitated by the initial assumption that all geographical units are the same size and shape, which allowed the use of geographic centroids in semivariogram estimation and kriging. Another implicit assumption was that the population at risk is uniformly distributed within each unit. This paper presents a generalization of Poisson kriging whereby the size and shape of administrative units, as well as the population density, is incorporated into the filtering of noisy mortality rates and the creation of isopleth risk maps. An innovative procedure to infer the point-support semivariogram of the risk from aggregated rates (i.e. areal data) is also proposed. Results The novel methodology is applied to age-adjusted lung and cervix cancer mortality rates recorded for white females in two contrasted county geographies: 1) state of Indiana that consists of 92 counties of fairly similar size and shape, and 2) four states in the Western US (Arizona, California, Nevada and Utah) forming a set of 118 counties that are vastly different geographical units. Area-to-point (ATP) Poisson kriging produces risk surfaces that are less smooth than the maps created by a naïve point kriging of empirical Bayesian smoothed rates. The coherence constraint of ATP kriging also ensures that the population-weighted average of risk estimates within each geographical unit equals the areal data for this unit. Simulation studies showed that the new approach yields more accurate predictions and confidence intervals than point kriging of areal data where all counties are simply collapsed into their respective polygon centroids. Its benefit over point kriging increases as the county geography becomes more heterogeneous. Conclusion A major limitation of choropleth maps is the common biased visual perception that larger rural and sparsely populated areas are of greater importance. The approach presented in this paper allows the continuous mapping of mortality risk, while accounting locally for population density and areal data through the coherence constraint. This form of Poisson kriging will facilitate the analysis of relationships between health data and putative covariates that are typically measured over different spatial supports. PMID:17137504

Temporal and spatial variability of rainfall pH

Treesearch

Richard G. Semonin

1977-01-01

The distribution of average rainwater pH over an area of 1,800 km² containing 81 collectors was determined from 25 storm events. The areal average of the data was pH 4.9, with a range of values from 4.3 to 6.8. A single storm event was studied to determine the change of pH as a function of time. The initial rain was pH 7.1, decreasing to 4.1. An excellent...

Land-cover effects on the fate and transport of surface-applied antibiotics and 17-beta-estradiol on a sandy outwash plain, Anoka County, Minnesota, 2008–09

USGS Publications Warehouse

Trost, Jared J.; Kiesling, Richard L.; Erickson, Melinda L.; Rose, Peter J.; Elliott, Sarah M.

2013-01-01

A plot-scale field experiment on a sandy outwash plain in Anoka County in east-central Minnesota was used to investigate the fate and transport of two antibiotics, sulfamethazine (SMZ) and sulfamethoxazole (SMX), and a hormone, 17-beta-estradiol (17BE), in four land-cover types: bare soil, corn, hay, and prairie. The SMZ, SMX, and 17BE were applied to the surface of five plots of each land-cover type in May 2008 and again in April 2009. The cumulative application rate was 16.8 milligrams per square meter (mg/m2) for each antibiotic and 0.6 mg/m2 for 17BE. Concentrations of each chemical in plant-tissue, soil, soil-water, and groundwater samples were determined by using enzyme-linked immunosorbent assay (ELISA) kits. Soil-water and groundwater sampling events were scheduled to capture the transport of SMZ, SMX, and 17BE during two growing seasons. Soil and plant-tissue sampling events were scheduled to identify the fate of the parent chemicals of SMZ, SMX, and 17BE in these matrices after two chemical applications. Areal concentrations (mg/m2) of SMZ and SMX in soil tended to decrease in prairie plots in the 8 weeks after the second chemical application, from April 2009 to June 2009, but not in other land-cover types. During these same 8 weeks, prairie plots produced more aboveground biomass and had extracted more water from the upper 125 centimeters of the soil profile compared to all other land-cover types. Areal concentrations of SMZ and SMX in prairie plant tissue did not explain the temporal changes in areal concentrations of these chemicals in soil. The areal concentrations of SMZ and SMX in the aboveground plant tissues in June 2009 and August 2009 were much lower, generally two to three orders of magnitude, than the areal concentrations of these chemicals in soil. Pooling all treatment plot data, the median areal concentration of SMZ and SMX in plant tissues was 0.01 and 0.10 percent of the applied chemical mass compared to 22 and 12 percent in soil, respectively. Furthermore, areal concentrations of SMZ and SMX in plant-tissue samples were variable, and did not differ significantly between control and treatment plots within each land-cover type. SMZ was detected in 23 percent of soil-water samples and in 16 percent of groundwater samples collected between October 2008 and October 2009 in treatment plots, indicating that surface-applied SMZ leached below the rooting zone and reached groundwater. SMX was detected in only 1 percent of soil-water and groundwater samples during this same time period. In contrast to the antibiotics, 17BE was not reliably detected in soil samples. Additionally, ELISA-determined 17BE concentrations in plant-tissue, soil-water, and groundwater samples indicated the presence of chemicals that were not applied as part of this experiment [17BE from an external source or other chemical(s) that interfered with the 17BE ELISA kits].

Shock-induced perturbation evolution in planar laser targets

NASA Astrophysics Data System (ADS)

Aglitskiy, Y.; Karasik, M.; Velikovich, A. L.; Serlin, V.; Weaver, J. L.; Kessler, T. J.; Schmitt, A. J.; Obenschain, S. P.; Metzler, N.; Oh, J.

2013-10-01

Experimental studies of hydrodynamic perturbation evolution triggered by a laser-driven shock wave in a planar target done on the KrF Nike laser facility are reported. The targets were made of solid plastic and/or plastic foam with single mode sinusoidal perturbation on the front or back surface or plastic/foam interface. Two specific cases are discussed. When a planar solid plastic target rippled at the front side is irradiated with a 350 ps long laser pulse, ablative Richtmyer-Meshkov (RM) oscillation of its areal mass modulation amplitude is detected while the laser is on, followed by observed strong oscillations of the areal mass in the unsupported shock flow after the laser pulse ends. When the target is rippled at the rear side, the nature of the perturbation evolution after the shock breakout is determined by the strength of the laser-driven shock wave. At pressure below 1 Mbar shock interaction with rear-surface ripples produces planar collimated jets manifesting the development of a classical RM instability in a weakly compressible shocked fluid. At shock pressure ~ 8 Mbar sufficient for vaporizing the shocked target material we observed instead the strong areal mass oscillations characteristic of a rippled centered rarefaction wave. Work supported by US DOE, Defense Programs.

Locally induced neuronal synchrony precisely propagates to specific cortical areas without rhythm distortion.

PubMed

Toda, Haruo; Kawasaki, Keisuke; Sato, Sho; Horie, Masao; Nakahara, Kiyoshi; Bepari, Asim K; Sawahata, Hirohito; Suzuki, Takafumi; Okado, Haruo; Takebayashi, Hirohide; Hasegawa, Isao

2018-05-16

Propagation of oscillatory spike firing activity at specific frequencies plays an important role in distributed cortical networks. However, there is limited evidence for how such frequency-specific signals are induced or how the signal spectra of the propagating signals are modulated during across-layer (radial) and inter-areal (tangential) neuronal interactions. To directly evaluate the direction specificity of spectral changes in a spiking cortical network, we selectively photostimulated infragranular excitatory neurons in the rat primary visual cortex (V1) at a supra-threshold level with various frequencies, and recorded local field potentials (LFPs) at the infragranular stimulation site, the cortical surface site immediately above the stimulation site in V1, and cortical surface sites outside V1. We found a significant reduction of LFP powers during radial propagation, especially at high-frequency stimulation conditions. Moreover, low-gamma-band dominant rhythms were transiently induced during radial propagation. Contrastingly, inter-areal LFP propagation, directed to specific cortical sites, accompanied no significant signal reduction nor gamma-band power induction. We propose an anisotropic mechanism for signal processing in the spiking cortical network, in which the neuronal rhythms are locally induced/modulated along the radial direction, and then propagate without distortion via intrinsic horizontal connections for spatiotemporally precise, inter-areal communication.

Coccolithophore surface distributions in the North Atlantic and their modulation of the air-sea flux of CO2 from 10 years of satellite Earth observation data

NASA Astrophysics Data System (ADS)

Shutler, J. D.; Land, P. E.; Brown, C. W.; Findlay, H. S.; Donlon, C. J.; Medland, M.; Snooke, R.; Blackford, J. C.

2013-04-01

Coccolithophores are the primary oceanic phytoplankton responsible for the production of calcium carbonate (CaCO3). These climatically important plankton play a key role in the oceanic carbon cycle as a major contributor of carbon to the open ocean carbonate pump (~50%) and their calcification can affect the atmosphere-to-ocean (air-sea) uptake of carbon dioxide (CO2) through increasing the seawater partial pressure of CO2 (pCO2). Here we document variations in the areal extent of surface blooms of the globally important coccolithophore, Emiliania huxleyi, in the North Atlantic over a 10-year period (1998-2007), using Earth observation data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). We calculate the annual mean sea surface areal coverage of E. huxleyi in the North Atlantic to be 474 000 ± 104 000 km2, which results in a net CaCO3 carbon (CaCO3-C) production of 0.14-1.71 Tg CaCO3-C per year. However, this surface coverage (and, thus, net production) can fluctuate inter-annually by -54/+8% about the mean value and is strongly correlated with the El Niño/Southern Oscillation (ENSO) climate oscillation index (r=0.75, p<0.02). Our analysis evaluates the spatial extent over which the E. huxleyi blooms in the North Atlantic can increase the pCO2 and, thus, decrease the localised air-sea flux of atmospheric CO2. In regions where the blooms are prevalent, the average reduction in the monthly air-sea CO2 flux can reach 55%. The maximum reduction of the monthly air-sea CO2 flux in the time series is 155%. This work suggests that the high variability, frequency and distribution of these calcifying plankton and their impact on pCO2 should be considered if we are to fully understand the variability of the North Atlantic air-to-sea flux of CO2. We estimate that these blooms can reduce the annual N. Atlantic net sink atmospheric CO2 by between 3-28%.

Foraging patterns and prey selection in an increasing and expanding sea otter population

USGS Publications Warehouse

Laidre, K.L.; Jameson, R.J.

2006-01-01

Focal observations of sea otter (Enhydra lutris kenyoni) foraging patterns and prey selection were collected in coastal Washington between 1993 and 1999. Records consisted of 13,847 individual dives from 841 feeding bouts ranging from 1 min to >4 h. Average dive time was 55 s ?? 0.9 SE and average surface time was 45 s ?? 2.3 SE, irrespective of dive success. At least 77% of all dives (n = 10,636) were successful prey captures (dives in low light or of undetermined success were excluded). Prey capture success was significantly lower for subadults (63% ?? 5 SE) than adults (82% ?? 1 SE; P 60% red urchins (Strongylocentrotus franciscanus), with only 2 other prey species comprising >10% of their diet. Prey size and prey category were dominant predictor variables in generalized linear models of dive duration and postdive surface duration on successful dives. Significant increases in areal extent of surface canopy of giant kelp (Macrocystis integrifolia) and bull kelp (Nereocystis leutkeana) were found both in the outer coast and the Strait of Juan de Fuca (0.4-0.5 km2 per year, P < 0.05) and suggest increasing suitable habitat for a growing population. The growth and expansion of a small and isolated sea otter population provides a unique opportunity to examine the relationship between dietary diversity and population status and explore similarities and differences between trophic paradigms established for sea otter populations at other localities. ?? 2006 American Society of Mammalogists.

Advances in sublimation studies for particles of explosives

NASA Astrophysics Data System (ADS)

Furstenberg, Robert; Nguyen, Viet; Fischer, Thomas; Abrishami, Tara; Papantonakis, Michael; Kendziora, Chris; Mott, David R.; McGill, R. Andrew

2015-05-01

When handling explosives, or related surfaces, the hands routinely become contaminated with particles of explosives and related materials. Subsequent contact with a solid surface results in particle crushing and deposition. These particles provide an evidentiary trail which is useful for security applications. As such, the opto-physico-chemical characteristics of these particles are critical to trace explosives detection applications in DOD or DHS arenas. As the persistence of these particles is vital to their forensic exploitation, it is important to understand which factors influence their persistence. The longevity or stability of explosives particles on a substrate is a function of several environmental parameters or particle properties including: Vapor pressure, particle geometry, airflow, particle field size, substrate topography, humidity, reactivity, adlayers, admixtures, particle areal density, and temperature. In this work we deposited particles of 2,4-dinitrotoluene on standard microscopy glass slides by particle sieving and studied their sublimation as a function of airflow velocity, areal particle density and particle field size. Analysis of 2D microscopic images was used to compute and track particle size and geometrical characteristics. The humidity, temperature and substrate type were kept constant for each experiment. A custom airflow cell, using standard microscopy glass slide, allowed in-situ photomicroscopy. Areal particle densities and airflow velocities were selected to provide relevant loadings and flow velocities for a range of potential applications. For a chemical of interest, we define the radial sublimation velocity (RSV) for the equivalent sphere of a particle as the parameter to characterize the sublimation rate. The RSV is a useful parameter because it is independent of particle size. The sublimation rate for an ensemble of particles was found to significantly depend on airflow velocity, the areal density of the particles, and the particle field size. To compare sublimation studies these parameters must be known.

A conditional stochastic weather generator for seasonal to multi-decadal simulations

NASA Astrophysics Data System (ADS)

Verdin, Andrew; Rajagopalan, Balaji; Kleiber, William; Podestá, Guillermo; Bert, Federico

2018-01-01

We present the application of a parametric stochastic weather generator within a nonstationary context, enabling simulations of weather sequences conditioned on interannual and multi-decadal trends. The generalized linear model framework of the weather generator allows any number of covariates to be included, such as large-scale climate indices, local climate information, seasonal precipitation and temperature, among others. Here we focus on the Salado A basin of the Argentine Pampas as a case study, but the methodology is portable to any region. We include domain-averaged (e.g., areal) seasonal total precipitation and mean maximum and minimum temperatures as covariates for conditional simulation. Areal covariates are motivated by a principal component analysis that indicates the seasonal spatial average is the dominant mode of variability across the domain. We find this modification to be effective in capturing the nonstationarity prevalent in interseasonal precipitation and temperature data. We further illustrate the ability of this weather generator to act as a spatiotemporal downscaler of seasonal forecasts and multidecadal projections, both of which are generally of coarse resolution.

Permafrost thaw and fire history: implications of boreal tree cover changes on land surface properties and turbulent energy fluxes in the Taiga Plains, Canada

NASA Astrophysics Data System (ADS)

Sonnentag, Oliver; Helbig, Manuel; Payette, Fanny; Wischnewski, Karoline; Kljun, Natascha; Chasmer, Laura; Pappas, Christoforos; Detto, Matteo; Baltzer, Jennifer; Quinton, William; Marsh, Philip

2016-04-01

Given their large areal coverage, high carbon densities, and unique land surface properties and disturbance regimes (e.g., wildfires), the world's boreal forests are integral components of the global and regional climate systems. A large portion of boreal forests contain permafrost, i.e., perennially cryotic ground. In the Taiga Plains ecozone in northwestern Canada, the northernmost boreal forests grow on cold (<-1.5 °C) and thick (>100 m) continuous permafrost (>90 % in areal extent). More southerly boreal forests occur in areas with discontinuous (>50 - 90 % in areal extent), sporadic (>10 - 50 % in areal extent) and isolated permafrost (<10 % in areal extent). Using annual MODIS Percent Tree Cover (PTC) data from the MOD44B product in combination with spatial information on fire history, and permafrost and drainage characteristics, we show that in low-lying, poorly-drained areas along the southern fringe of permafrost, thawing induces widespread decreases in PTC and dominates over PTC increases due to post-fire regrowth. In contrast, PTC appears to be slightly increasing in the central and northern Taiga Plains with more stable discontinuous and continuous permafrost, respectively. While these increases are partly explained by post-fire regrowth, more favourable growing conditions may also contribute to increasing PTC. To better understand the implications of permafrost thaw on land surface properties (e.g., aerodynamic conductance for heat [ga] and surface conductance for water vapour [gs]), and the turbulent fluxes of latent (LE) and sensible heat (H) along the southern fringe of permafrost, we examined nested eddy covariance flux measurements made at two nearby locations at Scotty Creek (61°18' N; 121°18' W) starting May 2013. The low-lying, poorly-drained southern portion of this 152 km2-watershed contains rapidly thawing sporadic permafrost resulting in a highly dynamic mosaic dominated by decreasing forested permafrost peat plateaus, and increasing permafrost-free wetlands. The spatial heterogeneities within the eddy covariance flux footprints (forest/wetland vs. wetland) were resolved with a two-dimensional footprint model parameterized with various remote sensing data sets. Our results suggest that an increasing coverage of wetlands at the expense of forests reduces ga and thus the efficiency of the land surface to transfer heat to the atmosphere. At the same time gs is increased and thus more moisture is lost to the atmosphere from saturated wetland surfaces. The alteration of bulk transfer land surface properties lead to drastic decreases in Bowen ratios by reducing H and increasing LE with increasing coverage of wetlands. The most pronounced contrasts between forests and wetlands are observed in H during the late snow cover period in April. We used a similar set of eddy covariance flux measurements made concurrently at Havikpak Creek (68°19' N; 133°31' W) and Trail Valley Creek (68°44' N; 133°26' W), a boreal forest and a nearby tundra site in the boreal-tundra ecotone, respectively, as a first-order proxy for potentially increasing PTC under more stable permafrost conditions in contrast to Scotty Creek. Preliminary results indicate trends in ga, gs, H and LE opposite to those observed at Scotty Creek between forests and wetlands. Our study demonstrates diverging implications of boreal tree cover changes on land surface properties and turbulent energy fluxes, thus on regional climate system feedback directions and strengths, as a function of permafrost conditions and fire history.

Landscapes to riverscapes: bridging the gap between research and conservation of stream fishes

USGS Publications Warehouse

Fausch, Kurt D.; Torgersen, Christian E.; Baxter, Colden V.; Li, Hiram W.

2002-01-01

Woodcock (Philohela minor), earthworms, and soil samples were collected from January-March 1965, from fields in southeastern Louisiana approximately 3 years after discontinuance of areal treatments with heptachlor in this region. Heptachlor epoxide residues in woodcock averaged 0.42 ppm (dry weight), conspicuously lower than in 1961 and 1962. Residues of DDE in woodcock averaged 3.62 pprn, higher than in birds taken in the same area in 1961-62. Earthworms and soils contained traces of several organochlorine pesticides.

Estimating release of carbon from 1990 and 1991 forest fires in Alaska

NASA Technical Reports Server (NTRS)

Kaisischke, Eric S.; French, Nancy H. F.; Bourgeau-Chavez, Laura L.; Christensen, N. L., Jr.

1995-01-01

An improved method to estimate the amounts of carbon released during fires in the boreal forest zone of Alaska in 1990 and 1991 is described. This method divides the state into 64 distinct physiographic regions and estimates areal extent of five different land covers: two forest types, peat land, tundra, and nonvegetated. The areal extent of each cover type was estimated from a review of topographic maps of each region and observations on the distribution of foreat types within the state. Using previous observations and theoretical models for the two forest types found in interior Alaska, models of biomass accumulation as a function of stand age were developed. Stand age distributions for each region were determined using a statistical distribution based on fire frequency, which was from available long-term historical records. Estimates of the degree of biomass combusted were based on recent field observations as well as research reported in the literature. The location and areal extent of fires in this region for 1990 and 1991 were based on both field observations and analysis of satellite (advanced very high resolution radiometer (AVHRR)) data sets. Estimates of average carbon release for the two study years ranged between 2.54 and 3.00 kg/sq m, which are 2.2 to 2.6 times greater than estimates used in other studies of carbon release through biomass burning in boreal forests. Total average annual carbon release for the two years ranged between 0.012 and 0.018 Pg C/yr, with the lower value resulting from the AVHRR estimates of fire location and area.

Stable near-surface ocean salinity stratifications due to evaporation observed during STRASSE

NASA Astrophysics Data System (ADS)

Asher, William E.; Jessup, Andrew T.; Clark, Dan

2014-05-01

Under conditions with a large solar flux and low wind speed, a stably stratified warm layer forms at the ocean surface. Evaporation can then lead to an increase in salinity in the warm layer. A large temperature gradient will decrease density enough to counter the density increase caused by the salinity increase, forming a stable positive salinity anomaly at the surface. If these positive salinity anomalies are large in terms of the change in salinity from surface to the base of the gradient, if their areal coverage is a significant fraction of the satellite footprint, and if they persist long enough to be in the satellite field of view, they could be relevant for calibration and validation of L-band microwave salinity measurements. A towed, surface-following profiler was deployed from the N/O Thalassa during the Subtropical Atlantic Surface Salinity Experiment (STRASSE). The profiler measured temperature and conductivity in the surface ocean at depths of 10, 50, and 100 cm. The measurements show that positive salinity anomalies are common at the ocean surface for wind speeds less than 4 m s-1 when the average daily insolation is >300 W m-2 and the sea-to-air latent heat flux is greater than zero. A semiempirical model predicts the observed dependence of measured anomalies on environmental conditions. However, the model results and the field data suggest that these ocean surface salinity anomalies are not large enough in terms of the salinity difference to significantly affect microwave radiometric measurements of salinity.

Stratospheric areal distribution of water vapor burden and the jet stream

NASA Technical Reports Server (NTRS)

Kuhn, P. M.; Magaziner, E.; Stearns, L. P.

1976-01-01

Radiometrically inferred areal observations of the atmospheric water vapor burden have been made in the 270 to 520 per cm spectral band over western U.S. and the extreme eastern Pacific from the NASA C-141 Kuiper Airborne Observatory. Before this, very few observations from the upper troposphere and lower stratosphere over such a broad area have been made. A total of 30,600 individual observations from eight separate synoptic situations involving eight jet maxima were computer-averaged over 2-deg latitude x 2-deg longitude boxes and related to the polar continental jet. Mean water vapor burdens ranged from 0.00046 to 0.00143 g per sq cm at 13.4 km with a striking peak just north of the jet wind maximum over a region of strong upward vertical motion.

The control of hot-electron preheat in shock-ignition implosions

NASA Astrophysics Data System (ADS)

Trela, J.; Theobald, W.; Anderson, K. S.; Batani, D.; Betti, R.; Casner, A.; Delettrez, J. A.; Frenje, J. A.; Glebov, V. Yu.; Ribeyre, X.; Solodov, A. A.; Stoeckl, M.; Stoeckl, C.

2018-05-01

In the shock-ignition scheme for inertial confinement fusion, hot electrons resulting from laser-plasma instabilities can play a major role during the late stage of the implosion. This article presents the results of an experiment performed on OMEGA in the so-called "40 + 20 configuration." Using a recent calibration of the time-resolved hard x-ray diagnostic, the hot electrons' temperature and total energy were measured. One-dimensional radiation-hydrodynamic simulations have been performed that include hot electrons and are in agreement with the measured neutron-rate-averaged areal density. For an early spike launch, both experiment and simulations show the detrimental effect of hot electrons on areal density and neutron yield. For a later spike launch, this effect is minimized because of a higher compression of the target.

Outstanding supercapacitive properties of Mn-doped TiO2 micro/nanostructure porous film prepared by anodization method

PubMed Central

Ning, Xuewen; Wang, Xixin; Yu, Xiaofei; Zhao, Jianling; Wang, Mingli; Li, Haoran; Yang, Yang

2016-01-01

Mn-doped TiO2 micro/nanostructure porous film was prepared by anodizing a Ti-Mn alloy. The film annealed at 300 °C yields the highest areal capacitance of 1451.3 mF/cm2 at a current density of 3 mA/cm2 when used as a high-performance supercapacitor electrode. Areal capacitance retention is 63.7% when the current density increases from 3 to 20 mA/cm2, and the capacitance retention is 88.1% after 5,000 cycles. The superior areal capacitance of the porous film is derived from the brush-like metal substrate, which could greatly increase the contact area, improve the charge transport ability at the oxide layer/metal substrate interface, and thereby significantly enhance the electrochemical activities toward high performance energy storage. Additionally, the effects of manganese content and specific surface area of the porous film on the supercapacitive performance were also investigated in this work. PMID:26940546

Catchment-scale evaluation of pollution potential of urban snow at two residential catchments in southern Finland.

PubMed

Sillanpää, Nora; Koivusalo, Harri

2013-01-01

Despite the crucial role of snow in the hydrological cycle in cold climate conditions, monitoring studies of urban snow quality often lack discussions about the relevance of snow in the catchment-scale runoff management. In this study, measurements of snow quality were conducted at two residential catchments in Espoo, Finland, simultaneously with continuous runoff measurements. The results of the snow quality were used to produce catchment-scale estimates of areal snow mass loads (SML). Based on the results, urbanization reduced areal snow water equivalent but increased pollutant accumulation in snow: SMLs in a medium-density residential catchment were two- to four-fold higher in comparison with a low-density residential catchment. The main sources of pollutants were related to vehicular traffic and road maintenance, but also pet excrement increased concentrations to a high level. Ploughed snow can contain 50% of the areal pollutant mass stored in snow despite its small surface area within a catchment.

Three-dimensional modeling of the neutron spectrum to infer plasma conditions in cryogenic inertial confinement fusion implosions

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

Weilacher, F.; Radha, P. B.; Forrest, C.

Neutron-based diagnostics are typically used to infer compressed core conditions such as areal density and ion temperature in deuterium–tritium (D–T) inertial confinement fusion (ICF) implosions. Asymmetries in the observed neutron-related quantities are important to understanding failure modes in these implosions. Neutrons from fusion reactions and their subsequent interactions including elastic scattering and neutron-induced deuteron breakup reactions are tracked to create spectra. Here, it is shown that background subtraction is important for inferring areal density from backscattered neutrons and is less important for the forward-scattered neutrons. A three-dimensional hydrodynamic simulation of a cryogenic implosion on the OMEGA Laser System [T. R.more » Boehly et al., Opt. Commun. 133, 495 (1997)] using the hydrodynamic code HYDRA [M. M. Marinak et al., Phys. Plasmas 8, 2275 (2001)] is post-processed using the tracking code IRIS3D. It is shown that different parts of the neutron spectrum from the view can be mapped into different regions of the implosion, enabling an inference of an areal-density map. It is also shown that the average areal-density and an areal-density map of the compressed target can be reconstructed with a finite number of detectors placed around the target chamber. Ion temperatures are inferred from the width of the D–D and D–T fusion neutron spectra. Backgrounds can significantly alter the inferred ion temperatures from the D–D reaction, whereas they insignificantly influence the inferred D–T ion temperatures for the areal densities typical of OMEGA implosions. Asymmetries resulting in fluid flow in the core are shown to influence the absolute inferred ion temperatures from both reactions, although relative inferred values continue to reflect the underlying asymmetry pattern. The work presented here is part of the wide range of the first set of studies performed with IRIS3D. Finally, this code will continue to be used for post-processing detailed hydrodynamic simulations and interpreting observed neutron spectra in ICF implosions.« less

Three-dimensional modeling of the neutron spectrum to infer plasma conditions in cryogenic inertial confinement fusion implosions

DOE PAGES

Weilacher, F.; Radha, P. B.; Forrest, C.

2018-04-26

Neutron-based diagnostics are typically used to infer compressed core conditions such as areal density and ion temperature in deuterium–tritium (D–T) inertial confinement fusion (ICF) implosions. Asymmetries in the observed neutron-related quantities are important to understanding failure modes in these implosions. Neutrons from fusion reactions and their subsequent interactions including elastic scattering and neutron-induced deuteron breakup reactions are tracked to create spectra. Here, it is shown that background subtraction is important for inferring areal density from backscattered neutrons and is less important for the forward-scattered neutrons. A three-dimensional hydrodynamic simulation of a cryogenic implosion on the OMEGA Laser System [T. R.more » Boehly et al., Opt. Commun. 133, 495 (1997)] using the hydrodynamic code HYDRA [M. M. Marinak et al., Phys. Plasmas 8, 2275 (2001)] is post-processed using the tracking code IRIS3D. It is shown that different parts of the neutron spectrum from the view can be mapped into different regions of the implosion, enabling an inference of an areal-density map. It is also shown that the average areal-density and an areal-density map of the compressed target can be reconstructed with a finite number of detectors placed around the target chamber. Ion temperatures are inferred from the width of the D–D and D–T fusion neutron spectra. Backgrounds can significantly alter the inferred ion temperatures from the D–D reaction, whereas they insignificantly influence the inferred D–T ion temperatures for the areal densities typical of OMEGA implosions. Asymmetries resulting in fluid flow in the core are shown to influence the absolute inferred ion temperatures from both reactions, although relative inferred values continue to reflect the underlying asymmetry pattern. The work presented here is part of the wide range of the first set of studies performed with IRIS3D. Finally, this code will continue to be used for post-processing detailed hydrodynamic simulations and interpreting observed neutron spectra in ICF implosions.« less

Estimation of Supraglacial Dust and Debris Geochemical Composition via Satellite Reflectance and Emissivity

NASA Technical Reports Server (NTRS)

Casey, Kimberly Ann; Kaab, Andreas

2012-01-01

We demonstrate spectral estimation of supraglacial dust, debris, ash and tephra geochemical composition from glaciers and ice fields in Iceland, Nepal, New Zealand and Switzerland. Surface glacier material was collected and analyzed via X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD) for geochemical composition and mineralogy. In situ data was used as ground truth for comparison with satellite derived geochemical results. Supraglacial debris spectral response patterns and emissivity-derived silica weight percent are presented. Qualitative spectral response patterns agreed well with XRF elemental abundances. Quantitative emissivity estimates of supraglacial SiO2 in continental areas were 67% (Switzerland) and 68% (Nepal), while volcanic supraglacial SiO2 averages were 58% (Iceland) and 56% (New Zealand), yielding general agreement. Ablation season supraglacial temperature variation due to differing dust and debris type and coverage was also investigated, with surface debris temperatures ranging from 5.9 to 26.6 C in the study regions. Applications of the supraglacial geochemical reflective and emissive characterization methods include glacier areal extent mapping, debris source identification, glacier kinematics and glacier energy balance considerations.

THERMAL-ENERGY STORAGE IN A DEEP SANDSTONE AQUIFER IN MINNESOTA: FIELD OBSERVATIONS AND THERMAL ENERGY-TRANSPORT MODELING.

USGS Publications Warehouse

Miller, R.T.

1986-01-01

A study of the feasibility of storing heated water in a deep sandstone aquifer in Minnesota is described. The aquifer consists of four hydraulic zones that are areally anisotropic and have average hydraulic conductivities that range from 0. 03 to 1. 2 meters per day. A preliminary axially symmetric, nonisothermal, isotropic, single-phase, radial-flow, thermal-energy-transport model was constructed to investigate the sensitivity of model simulation to various hydraulic and thermal properties of the aquifer. A three-dimensional flow and thermal-energy transport model was constructed to incorporate the areal anisotropy of the aquifer. Analytical solutions of equations describing areally anisotropic groundwater flow around a doublet-well system were used to specify model boundary conditions for simulation of heat injection. The entire heat-injection-testing period of approximately 400 days was simulated. Model-computed temperatures compared favorably with field-recorded temperatures, with differences of no more than plus or minus 8 degree C. For each test cycle, model-computed aquifer thermal efficiency, defined as total heat withdrawn divided by total heat injected, was within plus or minus 2% of the field-calculated values.

Lightweight Carbon-Carbon High-Temperature Space Radiator

NASA Technical Reports Server (NTRS)

Miller, W.O.; Shih, Wei

2008-01-01

A document summarizes the development of a carbon-carbon composite radiator for dissipating waste heat from a spacecraft nuclear reactor. The radiator is to be bonded to metal heat pipes and to operate in conjunction with them at a temperature approximately between 500 and 1,000 K. A goal of this development is to reduce the average areal mass density of a radiator to about 2 kg/m(exp 2) from the current value of approximately 10 kg/m(exp 2) characteristic of spacecraft radiators made largely of metals. Accomplishments thus far include: (1) bonding of metal tubes to carbon-carbon material by a carbonization process that includes heating to a temperature of 620 C; (2) verification of the thermal and mechanical integrity of the bonds through pressure-cycling, axial-shear, and bending tests; and (3) construction and testing of two prototype heat-pipe/carbon-carbon-radiator units having different radiator areas, numbers of heat pipes, and areal mass densities. On the basis of the results achieved thus far, it is estimated that optimization of design could yield an areal mass density of 2.2 kg/m (exp 2) close to the goal of 2 kg/m(exp 2).

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.

Surface Ocean pCO2 Seasonality and Sea-Air CO2 Flux Estimates for the North American East Coast

NASA Technical Reports Server (NTRS)

Signorini, Sergio; Mannino, Antonio; Najjar, Raymond G., Jr.; Friedrichs, Marjorie A. M.; Cai, Wei-Jun; Salisbury, Joe; Wang, Zhaohui Aleck; Thomas, Helmuth; Shadwick, Elizabeth

2013-01-01

Underway and in situ observations of surface ocean pCO2, combined with satellite data, were used to develop pCO2 regional algorithms to analyze the seasonal and interannual variability of surface ocean pCO2 and sea-air CO2 flux for five physically and biologically distinct regions of the eastern North American continental shelf: the South Atlantic Bight (SAB), the Mid-Atlantic Bight (MAB), the Gulf of Maine (GoM), Nantucket Shoals and Georges Bank (NS+GB), and the Scotian Shelf (SS). Temperature and dissolved inorganic carbon variability are the most influential factors driving the seasonality of pCO2. Estimates of the sea-air CO2 flux were derived from the available pCO2 data, as well as from the pCO2 reconstructed by the algorithm. Two different gas exchange parameterizations were used. The SS, GB+NS, MAB, and SAB regions are net sinks of atmospheric CO2 while the GoM is a weak source. The estimates vary depending on the use of surface ocean pCO2 from the data or algorithm, as well as with the use of the two different gas exchange parameterizations. Most of the regional estimates are in general agreement with previous studies when the range of uncertainty and interannual variability are taken into account. According to the algorithm, the average annual uptake of atmospheric CO2 by eastern North American continental shelf waters is found to be between 3.4 and 5.4 Tg C/yr (areal average of 0.7 to 1.0 mol CO2 /sq m/yr) over the period 2003-2010.

Shell stability and conditions analyzed using a new method of extracting shell areal density maps from spectrally resolved images of direct-drive inertial confinement fusion implosions

DOE PAGES

Johns, H. M.; Mancini, R. C.; Nagayama, T.; ...

2016-01-25

In warm target direct-drive inertial confinement fusion implosion experiments performed at the OMEGA laser facility, plastic micro-balloons doped with a titanium tracer layer in the shell and filled with deuterium gas were imploded using a low-adiabat shaped laser pulse. Continuum radiation emitted in the core is transmitted through the tracer layer and the resulting spectrum recorded with a gated multi-monochromatic x-ray imager (MMI). Titanium K-shell line absorption spectra observed in the data are due to transitions in L-shell titanium ions driven by the backlighting continuum. The MMI data consist of an array of spectrally resolved images of the implosion. Thesemore » 2-D space-resolved titanium spectral features constrain the plasma conditions and areal density of the titanium doped region of the shell. The MMI data were processed to obtain narrow-band images and space resolved spectra of titanium spectral features. Shell areal density maps, ρL(x,y), extracted using a new method using both narrow-band images and space resolved spectra are confirmed to be consistent within uncertainties. We report plasma conditions in the titanium-doped region of electron temperature (Te) = 400 ± 28 eV, electron number density (N e) = 8.5 × 10 24 ± 2.5 × 10 24 cm –3, and average areal density = 86 ± 7 mg/cm 2. Fourier analysis of areal density maps reveals shell modulations caused by hydrodynamic instability growth near the fuel-shell interface in the deceleration phase. We observe significant structure in modes l = 2–9, dominated by l = 2. We extract a target breakup fraction of 7.1 ± 1.5% from our Fourier analysis. Furthermore, a new method for estimating mix width is evaluated against existing literature and our target breakup fraction. We estimate a mix width of 10.5 ±1 μm.« less

Guide to Magellan image interpretation

NASA Technical Reports Server (NTRS)

Ford, John P.; Plaut, Jeffrey J.; Weitz, Catherine M.; Farr, Tom G.; Senske, David A.; Stofan, Ellen R.; Michaels, Gregory; Parker, Timothy J.; Fulton, D. (Editor)

1993-01-01

An overview of Magellan Mission requirements, radar system characteristics, and methods of data collection is followed by a description of the image data, mosaic formats, areal coverage, resolution, and pixel DN-to-dB conversion. The availability and sources of image data are outlined. Applications of the altimeter data to estimate relief, Fresnel reflectivity, and surface slope, and the radiometer data to derive microwave emissivity are summarized and illustrated in conjunction with corresponding SAR image data. Same-side and opposite-side stereo images provide examples of parallax differences from which to measure relief with a lateral resolution many times greater than that of the altimeter. Basic radar interactions with geologic surfaces are discussed with respect to radar-imaging geometry, surface roughness, backscatter modeling, and dielectric constant. Techniques are described for interpreting the geomorphology and surface properties of surficial features, impact craters, tectonically deformed terrain, and volcanic landforms. The morphologic characteristics that distinguish impact craters from volcanic craters are defined. Criteria for discriminating extensional and compressional origins of tectonic features are discussed. Volcanic edifices, constructs, and lava channels are readily identified from their radar outlines in images. Geologic map units are identified on the basis of surface texture, image brightness, pattern, and morphology. Superposition, cross-cutting relations, and areal distribution of the units serve to elucidate the geologic history.

An integrated Bayesian model for estimating the long-term health effects of air pollution by fusing modelled and measured pollution data: A case study of nitrogen dioxide concentrations in Scotland.

PubMed

Huang, Guowen; Lee, Duncan; Scott, Marian

2015-01-01

The long-term health effects of air pollution can be estimated using a spatio-temporal ecological study, where the disease data are counts of hospital admissions from populations in small areal units at yearly intervals. Spatially representative pollution concentrations for each areal unit are typically estimated by applying Kriging to data from a sparse monitoring network, or by computing averages over grid level concentrations from an atmospheric dispersion model. We propose a novel fusion model for estimating spatially aggregated pollution concentrations using both the modelled and monitored data, and relate these concentrations to respiratory disease in a new study in Scotland between 2007 and 2011. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

The control of hot-electron preheat in shock-ignition implosions

DOE PAGES

Trela, J.; Theobald, W.; Anderson, K. S.; ...

2018-05-22

In the shock-ignition scheme for inertial confinement fusion, hot electrons resulting from laser–plasma instabilities can play a major role during the late stage of the implosion. This article presents the results of an experiment performed on OMEGA in the so-called “40 + 20 configuration.” Using a recent calibration of the time-resolved hard x-ray diagnostic, the hot electrons’ temperature and total energy were measured. One-dimensional radiation–hydrodynamic simulations have been performed that include hot electrons and are in agreement with the measured neutron-rate–averaged areal density. For an early spike launch, both experiment and simulations show the detrimental effect of hot electrons onmore » areal density and neutron yield. Lastly, for a later spike launch, this effect is minimized because of a higher compression of the target.« less

The control of hot-electron preheat in shock-ignition implosions

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

Trela, J.; Theobald, W.; Anderson, K. S.

In the shock-ignition scheme for inertial confinement fusion, hot electrons resulting from laser–plasma instabilities can play a major role during the late stage of the implosion. This article presents the results of an experiment performed on OMEGA in the so-called “40 + 20 configuration.” Using a recent calibration of the time-resolved hard x-ray diagnostic, the hot electrons’ temperature and total energy were measured. One-dimensional radiation–hydrodynamic simulations have been performed that include hot electrons and are in agreement with the measured neutron-rate–averaged areal density. For an early spike launch, both experiment and simulations show the detrimental effect of hot electrons onmore » areal density and neutron yield. For a later spike launch, this effect is minimized because of a higher compression of the target.« less

Design and characterization of textured surfaces for applications in the food industry

NASA Astrophysics Data System (ADS)

Lazzini, G.; Romoli, L.; Blunt, L.; Gemini, L.

2017-12-01

The aim of this work is to design, manufacture and characterize surface morphologies on AISI 316L stainless steel produced by a custom designed laser-texturing strategy. Surface textures were characterized at a micrometric dimension in terms of areal parameters compliant with ISO 25178, and correlations between these parameters and processing parameters (e.g. laser energy dose supplied to the material, repetition rate of the laser pulses and scanning velocity) were investigated. Preliminary efforts were devoted to the research of special requirements for surface morphology that, according to the commonly accepted research on the influence of surface roughness on cellular adhesion on surfaces, should discourage the formation of biofilms. The topographical characterization of the surfaces was performed with a coherence scanning interferometer. This approach showed that increasing doses of energy to the surfaces increased the global level of roughness as well as the surface complexity. Moreover, the behavior of the parameters S pk, S vk also indicates that, due to the ablation process, an increase in the energy dose causes an average increase in the height of the highest peaks and in the depth of the deepest dales. The study of the density of peaks S pd showed that none of the surfaces analyzed here seem to perfectly match the conditions dictated by the theories on cellular adhesion to confer anti-biofouling properties. However, this result seems to be mainly due to the limits of the resolving power of coherence scanning interferometry, which does not allow the resolution of sub-micrometric features which could be crucial in the prevention of cellular attachment.

Photogrammetric and Global Positioning System Measurements of Active Pahoehoe Lava Lobe Emplacement on Kilauea, Hawaii

NASA Technical Reports Server (NTRS)

Hamilton, Christopher W.; Glaze, Lori S.; James, Mike R.; Baloga, Stephen M.; Fagents, Sarah A.

2012-01-01

Basalt is the most common rock type on the surface of terrestrial bodies throughout the solar system and -- by total volume and areal coverage -- pahoehoe flows are the most abundant form of basaltic lava in subaerial and submarine environments on Earth. A detailed understanding of pahoehoe emplacement processes is necessary for developing accurate models of flow field development, assessing hazards associated with active lava flows, and interpreting the significance of lava flow morphology on Earth and other planetary bodies. Here, we examine the active emplacement of pahoehoe lobes along the margins of the Hook Flow from Pu'u 'O'o on Kilauea, Hawaii. Topographic data were acquired between 21 and 23 February 2006 using stereo-imaging and differential global positing system (DGPS) measurements. During this time, the average discharge rate for the Hook Flow was 0.01-0.05 cubic m/s. Using stereogrammetric point clouds and interpolated digital terrain models (DTMs), active flow fronts were digitized at 1 minute intervals. These areal spreading maps show that the lava lobe grew by a series of breakouts tha t broadly fit into two categories: narrow (0.2-0.6 m-wide) toes that grew preferentially down-slope, and broad (1.4-3.5 m-wide) breakouts that formed along the sides of the lobe, nearly perpendicular to the down-flow axis. These lobes inflated to half of their final thickness within approx 5 minutes, with a rate of inflation that generally deceased with time. Through a combination of down-slope and cross-slope breakouts, lobes developed a parabolic cross-sectional shape within tens of minutes. We also observed that while the average local discharge rate for the lobe was generally constant at 0.0064 +/- 0.0019 cubic m/s, there was a 2 to 6 fold increase in the areal coverage rate every 4.1 +/- 0.6 minutes. We attribute this periodicity to the time required for the dynamic pressurization of the liquid core of the lava lobe to exceed the cooling-induced strength of the lobe margins. Using DGPS-derived DTMs of the topography before and after pahoehoe lobe emplacement, we observed that the lava typically concentrated within existing topographic lows, with the lobe reaching a maximum thickness of approx 1.2 m above the lowest points of the initial topography and above reverse-facing slopes. Lobe margins were typically controlled by high-standing topography, with the zone directly adjacent to the final flow margin having average relief that is approx 4 cm higher than the lava-inundated region. This suggests that irregularities approx 25% of the height of the smallest breakout elements (i.e., toes) can exert a strong control on the paths of low-discharge pahoehoe lobes, with stagnated toes forming confining margins that allow interior portions of flow to topographically invert the landscape by inflation.

Hydrology Prior to Wetland and Prairie Restoration in and around the Glacial Ridge National Wildlife Refuge, Northwestern Minnesota, 2002-5

USGS Publications Warehouse

Cowdery, Timothy K.; Lorenz, David L.; Arntson, Allan D.

2008-01-01

The Nature Conservancy (TNC) owned and managed 24,795 acres of mixed wetland, native prairie, farmland and woods east of Crookston, in northwestern Minnesota. The original wetlands and prairies that once occupied this land are being restored by TNC in cooperation with many partners and are becoming part of the Glacial Ridge National Wildlife Refuge. Results of this study indicate that these restorations are likely to have a substantial effect on the local hydrology. Water occurs within the study area on the land surface, in surficial aquifers, and in buried aquifers of various depths, the tops of which are 50 to several hundred feet below the land surface. Surficial aquifers are generally thin (about 20 feet), narrow (several hundred feet), and long (tens of miles). Estimates of the horizontal hydraulic conductivity of surficial aquifers were 2.7?300 feet per day. Buried aquifers underlie much of the study area, but interact with surficial aquifers only in isolated areas. In these areas, water flows directly from buried to surficial aquifers and forms a single aquifer as much as 78 feet thick. The surface?water channel network is modified by several manmade ditches that were installed to remove excess water seasonally and to drain wetlands. The channels of the network lie primarily parallel to the beach ridges but cut through them in places. Back?beach basin wetlands delay and reduce direct runoff to ditches. Recharge to the surficial aquifers (10.97?25.08 inches per year during 2003?5) is from vertical infiltration of rainfall and snowmelt (areal recharge); from surface waters (particularly ephemeral wetlands); and from upward leakage of water from buried aquifers through till confining units (estimated at about 1 inch per year). Areal recharge is highly variable in space and time. Water leaves (discharges from) the surficial aquifers as flow to surface waters (closed basins and ditches), evapotranspiration, and withdrawals from wells. Unmeasured losses (primarily discharge to ungaged (closed) basins) were 53?115 percent of areal recharge during 2003?5, while discharge to ditches that leave the study area was 17?41 percent. Discharge over 100 percent of areal recharge indicates a loss in ground?water storage. During the dry year of 2003, substantial ground water (about one?third of annual areal recharge) was released from aquifer storage but was replenished quickly during the subsequent normal year. Shallow ground?water flow is complex, with water in surficial aquifers, ditches, and wetlands part of a single hydrologic system. The ages determined for surficial ground?water samples were less than 15 years old, and one?third (8 of 24) were less than 5 years old, substantiating the close connection of surficial ground water to the land surface. During the study, 68?81 percent of water left the area through unmeasured surface?water losses (primarily evapotranspiration), which is 2? to 4?times that leaving through the ditch system. Base flow in ditches (ground?water discharge) was 30 to 71 percent of all ditch flow. Mean annual runoff in all gaged basins except SW3 (2.26 inches per year) was similar (3.69?4.12 inches per year). The quality of water samples from surficial aquifers and surface water collected in the study area was generally suitable for most uses but was variable. Most ground? and surface?water samples were dominated by calcium, magnesium, and bicarbonate ions. About one?quarter of surficial ground?water samples contained nitrate at concentrations greater than the U.S. Environmental Protection Agency?s (USEPA) Maximum Contaminant Level for human consumption. The median concentration of dissolved phosphorus ranged from 0.0108 milligrams per liter as phosphorus (mg/L?P) to 0.0293 mg/L?P. Nutrient concentrations in ditches were generally above the USEPA nutrient guidelines for reference streams in the area. Water samples contained detectable concentrations of atrazine, acetachlor, metolachlor, pendimethalin

Lagrangian analysis by clustering. An example in the Nordic Seas.

NASA Astrophysics Data System (ADS)

Koszalka, Inga; Lacasce, Joseph H.

2010-05-01

We propose a new method for obtaining average velocities and eddy diffusivities from Lagrangian data. Rather than grouping the drifter-derived velocities in uniform geographical bins, as is commonly done, we group a specified number of nearest-neighbor velocities. This is done via a clustering algorithm operating on the instantaneous positions of the drifters. Thus it is the data distribution itself which determines the positions of the averages and the areal extent of the clusters. A major advantage is that because the number of members is essentially the same for all clusters, the statistical accuracy is more uniform than with geographical bins. We illustrate the technique using synthetic data from a stochastic model, employing a realistic mean flow. The latter is an accurate representation of the surface currents in the Nordic Seas and is strongly inhomogeneous in space. We use the clustering algorithm to extract the mean velocities and diffusivities (both of which are known from the stochastic model). We also compare the results to those obtained with fixed geographical bins. Clustering is more successful at capturing spatial variability of the mean flow and also improves convergence in the eddy diffusivity estimates. We discuss both the future prospects and shortcomings of the new method.

Hydrothermal solid-gas route to TiO2 nanoparticles/nanotube arrays for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Fan, Haowen; Zhang, He; Luo, Xiaolei; Liao, Maoying; Zhu, Xufei; Ma, Jing; Song, Ye

2017-07-01

Although TiO2 nanotube arrays (TNTAs) have shown great promise as supercapacitor materials, their specific capacitances are still not comparable with some typical materials. Here, TiO2 nanoparticles (NPs)/TNTAs hybrid structure has been derived from the anodized TNTAs by a facile hydrothermal solid-gas method (HSGM), which can avoid cracking or curling of the TNTAs from Ti substrate. The obtained NPs/TNTAs hybrid structure can exhibit a ∼4.90 times increase in surface area and a ∼5.49 times increase in areal specific capacitance compared to the TNTAs without HSGM treatment. Besides, the argon-atmosphere annealing can offer improved areal capacitance and cycling stability relative to the air-atmosphere annealing. The hydrothermal vapor pressure is a key factor for controlling microscopic morphologies of TNTAs, the morphology transformations of TNTAs during the HSGM treatment can be accelerated under enhanced vapor pressures. The highest areal capacitance of HSGM-treated TNTAs is up to 76.12 mF cm-2 at 0.5 mA cm-2, well above that of any TiO2 materials reported to date.

Enabling aqueous processing for crack-free thick electrodes

DOE PAGES

Du, Zhijia; Rollag, K. M.; Li, J.; ...

2017-04-14

Aqueous processing of thick electrodes for Li-ion cells promises to increase energy density due to increased volume fraction of active materials, and to reduce cost due to the elimination of the toxic solvents. Here in this paper this work reports the processing and characterization of aqueous processed electrodes with high areal loading and associated full pouch cell performance. Cracking of the electrode coatings becomes a critical issue for aqueous processing of the positive electrode as areal loading increases above 20–25 mg/cm 2 (~4 mAh/cm 2). Crack initiation and propagation, which was observed during drying via optical microscopy, is related tomore » the build-up of capillary pressure during the drying process. The surface tension of water was reduced by the addition of isopropyl alcohol (IPA), which led to improved wettability and decreased capillary pressure during drying. The critical thickness (areal loading) without cracking increased gradually with increasing IPA content. The electrochemical performance was evaluated in pouch cells. Electrodes processed with water/IPA (80/20 wt%) mixture exhibited good structural integrity with good rate performance and cycling performance.« less

Finite-difference model to simulate the areal flow of saltwater and fresh water separated by an interface

USGS Publications Warehouse

Mercer, James W.; Larson, S.P.; Faust, Charles R.

1980-01-01

Model documentation is presented for a two-dimensional (areal) model capable of simulating ground-water flow of salt water and fresh water separated by an interface. The partial differential equations are integrated over the thicknesses of fresh water and salt water resulting in two equations describing the flow characteristics in the areal domain. These equations are approximated using finite-difference techniques and the resulting algebraic equations are solved for the dependent variables, fresh water head and salt water head. An iterative solution method was found to be most appropriate. The program is designed to simulate time-dependent problems such as those associated with the development of coastal aquifers, and can treat water-table conditions or confined conditions with steady-state leakage of fresh water. The program will generally be most applicable to the analysis of regional aquifer problems in which the zone between salt water and fresh water can be considered a surface (sharp interface). Example problems and a listing of the computer code are included. (USGS).

COASTAL SALT MARSH COMMUNITY CHANGE IN NARRAGANSETT BAY IN RESPONSE TO CULTURAL EUTROPHICATION

EPA Science Inventory

Coastal salt marshes are susceptible to cultural eutrophication, particularly the over-enrichment of nitrogen, because they are often located where surface water and groundwater discharge into estuaries. In this report, the current areal extent of coastal salt marshes in Narrag...

Preparing two-dimensional microporous carbon from Pistachio nutshell with high areal capacitance as supercapacitor materials

NASA Astrophysics Data System (ADS)

Xu, Jiandong; Gao, Qiuming; Zhang, Yunlu; Tan, Yanli; Tian, Weiqian; Zhu, Lihua; Jiang, Lei

2014-07-01

Two-dimensional (2D) porous carbon AC-SPN-3 possessing of amazing high micropore volume ratio of 83% and large surface area of about 1069 m2 g-1 is high-yield obtained by pyrolysis of natural waste Pistachio nutshells with KOH activation. The AC-SPN-3 has a curved 2D lamellar morphology with the thickness of each slice about 200 nm. The porous carbon is consists of highly interconnected uniform pores with the median pore diameter of about 0.76 nm, which could potentially improve the performance by maximizing the electrode surface area accessible to the typical electrolyte ions (such as TEA+, diameter = ~0.68 nm). Electrochemical analyses show that AC-SPN-3 has significantly large areal capacitance of 29.3/20.1 μF cm-2 and high energy density of 10/39 Wh kg-1 at power of 52/286 kW kg-1 in 6 M KOH aqueous electrolyte and 1 M TEABF4 in EC-DEC (1:1) organic electrolyte system, respectively.

Multivariate space-time modelling of multiple air pollutants and their health effects accounting for exposure uncertainty.

PubMed

Huang, Guowen; Lee, Duncan; Scott, E Marian

2018-03-30

The long-term health effects of air pollution are often estimated using a spatio-temporal ecological areal unit study, but this design leads to the following statistical challenges: (1) how to estimate spatially representative pollution concentrations for each areal unit; (2) how to allow for the uncertainty in these estimated concentrations when estimating their health effects; and (3) how to simultaneously estimate the joint effects of multiple correlated pollutants. This article proposes a novel 2-stage Bayesian hierarchical model for addressing these 3 challenges, with inference based on Markov chain Monte Carlo simulation. The first stage is a multivariate spatio-temporal fusion model for predicting areal level average concentrations of multiple pollutants from both monitored and modelled pollution data. The second stage is a spatio-temporal model for estimating the health impact of multiple correlated pollutants simultaneously, which accounts for the uncertainty in the estimated pollution concentrations. The novel methodology is motivated by a new study of the impact of both particulate matter and nitrogen dioxide concentrations on respiratory hospital admissions in Scotland between 2007 and 2011, and the results suggest that both pollutants exhibit substantial and independent health effects. © 2017 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.

The effect of climate anomalies and human ignition factor on wildfires in Russian boreal forests.

PubMed

Achard, Frédéric; Eva, Hugh D; Mollicone, Danilo; Beuchle, René

2008-07-12

Over the last few years anomalies in temperature and precipitation in northern Russia have been regarded as manifestations of climate change. During the same period exceptional forest fire seasons have been reported, prompting many authors to suggest that these in turn are due to climate change. In this paper, we examine the number and areal extent of forest fires across boreal Russia for the period 2002-2005 within two forest categories: 'intact forests' and 'non-intact forests'. Results show a far lower density of fire events in intact forests (5-14 times less) and that those events tend to be in the first 10 km buffer zone inside intact forest areas. Results also show that, during exceptional climatic years (2002 and 2003), fire event density is twice that found during normal years (2004 and 2005) and average areal extent of fire events (burned area) in intact forests is 2.5 times larger than normal. These results suggest that a majority of the fire events in boreal Russia are of human origin and a maximum of one-third of their impact (areal extension) can be attributed to climate anomalies alone, the rest being due to the combined effect of human disturbances and climate anomalies.

Geometric contribution leading to anomalous estimation of two-dimensional electron gas density in GaN based heterostructures

NASA Astrophysics Data System (ADS)

Upadhyay, Bhanu B.; Jha, Jaya; Takhar, Kuldeep; Ganguly, Swaroop; Saha, Dipankar

2018-05-01

We have observed that the estimation of two-dimensional electron gas density is dependent on the device geometry. The geometric contribution leads to the anomalous estimation of the GaN based heterostructure properties. The observed discrepancy is found to originate from the anomalous area dependent capacitance of GaN based Schottky diodes, which is an integral part of the high electron mobility transistors. The areal capacitance density is found to increase for smaller radii Schottky diodes, contrary to a constant as expected intuitively. The capacitance is found to follow a second order polynomial on the radius of all the bias voltages and frequencies considered here. In addition to the quadratic dependency corresponding to the areal component, the linear dependency indicates a peripheral component. It is further observed that the peripheral to areal contribution is inversely proportional to the radius confirming the periphery as the location of the additional capacitance. The peripheral component is found to be frequency dependent and tends to saturate to a lower value for measurements at a high frequency. In addition, the peripheral component is found to vanish when the surface is passivated by a combination of N2 and O2 plasma treatments. The cumulative surface state density per unit length of the perimeter of the Schottky diodes as obtained by the integrated response over the distance between the ohmic and Schottky contacts is found to be 2.75 × 1010 cm-1.

Membrane-constrained acoustic metamaterials for low frequency sound insulation

NASA Astrophysics Data System (ADS)

Wang, Xiaole; Zhao, Hui; Luo, Xudong; Huang, Zhenyu

2016-01-01

We present a constrained membrane-type acoustic metamaterial (CMAM) that employs constraint sticks to add out-of-plane dimensions in the design space of MAM. A CMAM sample, which adopts constraint sticks to suppress vibrations at the membrane center, was fabricated to achieve a sound transmission loss (STL) peak of 26 dB at 140 Hz, with the static areal density of 6.0 kg/m2. The working mechanism of the CMAM as an acoustic metamaterial is elucidated by calculating the averaged normal displacement, the equivalent areal density, and the effective dynamic mass of a unit cell through finite element simulations. Furthermore, the vibration modes of the CMAM indicate that the eigenmodes related to STL dips are shifted into high frequencies, thus broadening its effective bandwidth significantly. Three samples possessing the same geometry and material but different constraint areas were fabricated to illustrate the tunability of STL peaks at low frequencies.

Momentum transfer conduits -- A new microscopic look at porous media

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

Moaveni, S.

In this paper, the flow of fluid through porous media is investigated on a microscopic scale by representing a porous medium by an assemblage of hypothetical conduits through which the fluid momentum is transferred across the medium. It is shown that the rate of transfer of fluid momentum depends on the geometrical structure of the conduits such as the number density of momentum transfer conduits (MTCs), the length distribution and the directional distribution of these hypothetical conduits. In addition an expression for the total number of momentum transfer conduits reaching an arbitrary areal element is developed. Finally, an average heightmore » normal to an arbitrary areal element at which the MTCs were last discharged is formulated. This idea leads to definition of momentum thickness, which in turn may be used to define an effective (pseudo) viscosity for a given porous medium.« less

The Computerized Anatomical Man (CAM) model

NASA Technical Reports Server (NTRS)

Billings, M. P.; Yucker, W. R.

1973-01-01

A computerized anatomical man (CAM) model, representing the most detailed and anatomically correct geometrical model of the human body yet prepared, has been developed for use in analyzing radiation dose distribution in man. This model of a 50-percentile standing USAF man comprises some 1100 unique geometric surfaces and some 2450 solid regions. Internal body geometry such as organs, voids, bones, and bone marrow are explicitly modeled. A computer program called CAMERA has also been developed for performing analyses with the model. Such analyses include tracing rays through the CAM geometry, placing results on magnetic tape in various forms, collapsing areal density data from ray tracing information to areal density distributions, preparing cross section views, etc. Numerous computer drawn cross sections through the CAM model are presented.

Superposed ridges of the Hesperia Planum area on Mars

NASA Technical Reports Server (NTRS)

Raitala, Jouko

1988-01-01

Mare ridges of the Hesperia Planum area form linear, reticular and circular structures. The main factors effective in mare ridge formation have been: (1) a large areal, or maybe even global, shortening and compression, (2) major crustal tectonics, and (3) the moderation of tectonic movements by the megaregolith discontinuity layer(s) between surface lavas and the bedrock leaving the compressional thrust to dominate over other fault movements in surface tectonics.

Extent of areal inundation of riverine wetlands along Cypress Creek and the Peace, Alafia, North Prong Alafia, and South Prong Alafia Rivers, west-central Florida

USGS Publications Warehouse

Lewelling, B.R.

2003-01-01

Riverine and palustrine system wetlands are a major ecological component of river basins in west-central Florida. Healthy wetlands are dependent upon the frequency and duration of periodic flooding or inundation. This report assesses the extent, area, depth, frequency, and duration of periodic flooding and the effects of potential surface-water withdrawals on the wetlands along Cypress Creek and the Peace, Alafia, North Prong Alafia, and South Prong Alafia Rivers. Results of the study were derived from step-backwater analysis performed at each of the rivers using the U.S. Army Corps of Engineers Hydrologic Engineering Center-River Analysis System (HEC-RAS) one-dimensional model. The step-backwater analysis was performed using selected daily mean discharges at the 10th, 50th, 70th, 80th, 90th, 98th, 99.5th, and 99.9th percentiles to compute extent of areal inundation, area of inundation, and hydraulic depth to assess the net reduction of areal inundation if 10 percent of the total river flow were diverted for potential withdrawals. The extent of areal inundation is determined by cross-sectional topography and the degree to which the channel is incised. Areal inundation occurs along the broad, low relief of the Cypress Creek floodplain during all selected discharge percentiles. However, areal inundation of the Peace and Alafia Rivers floodplains, which generally have deeply incised channels, occurs at or above discharges at the 80th percentile. The greatest area of inundation along the three rivers generally occurs between the 90th and 98th percentile discharges. The decrease in inundated area resulting from a potential 10-percent withdrawal in discharge ranged as follows: Cypress Creek, 22 to 395 acres (1.7 to 8.4 percent); Peace River, 17 to 1,900 acres (2.1 to 13.6 percent); Alafia River, 1 to 90 acres (1 to 19.6 percent); North Prong Alafia River, 1 to 46 acres (0.7 to 23.4 percent); and South Prong Alafia River, 1 to 75 acres (1.5 to 13.4 percent).

Methane flux from Minnesota Peatlands

NASA Astrophysics Data System (ADS)

Crill, P. M.; Bartlett, K. B.; Harriss, R. C.; Gorham, E.; Verry, E. S.; Sebacher, D. I.; Madzar, L.; Sanner, W.

1988-12-01

Northern (>40°N) wetlands have been suggested as the largest natural source of methane (CH4) to the troposphere. To refine our estimates of source strengths from this region and to investigate climatic controls on the process, fluxes were measured from a variety of Minnesota peatlands during May, June, and August 1986. Sites included forested and unforested ombrotrophic bogs and minerotrophic fens in and near the U.S. Department of Agriculture Marcell Experimental Forest and the Red Lake peatlands. Late spring and summer fluxes ranged from 11 to 866 mg CH4 m-2 d-1, averaging 207 mg CH4 m-2 d-1 overall. At Marcell Forest, forested bogs and fen sites had lower fluxes (averages of 77 ± 21 mg CH4 m-2 d-1 and 142 ± 19 mg CH4 m-2 d-1) than open bogs (average of 294 ± 30 mg CH4 m-2 d-1). In the Red Lake peatland, circumneutral fens, with standing water above the peat surface, produced more methane than acid bog sites in which the water table was beneath the moss surface (325 ± 31 and 102 ± 13 mg CH4 m-2 d-1, respectively). Peat temperature was an important control. Methane flux increased in response to increasing soil temperature. For example, the open bog in the Marcell Forest with the highest CH4 flux exhibited a 74-fold increase in flux over a three-fold increase in temperature. We estimate that the methane flux from all peatlands north of 40° may be on the order of 70 to 90 Tg/yr though estimates of this sort are plagued by uncertainties in the areal extent of peatlands, length of the CH4 producing season, and the spatial and temporal variability of the flux.

Plains Tectonics on Venus

NASA Technical Reports Server (NTRS)

Banerdt, W. B.; McGill, G. E.; Zuber, M. T.

1996-01-01

Tectonic deformation in the plains of Venus is pervasive, with virtually every area of the planet showing evidence for faulting or fracturing. This deformation can be classified into three general categories, defined by the intensity and areal extent of the surface deformation: distributed deformation, concentrated deformation, and local fracture patterns.

Radar evidence for liquid surfaces on Titan.

PubMed

Campbell, Donald B; Black, Gregory J; Carter, Lynn M; Ostro, Steven J

2003-10-17

Arecibo radar observations of Titan at 13-centimeter wavelength indicate that most of the echo power is in a diffusely scattered component but that a small specular component is present for about 75% of the subearth locations observed. These specular echoes have properties consistent with those expected for areas of liquid hydrocarbons. Knowledge of the areal extent and depth of any deposits of liquid hydrocarbons could strongly constrain the history of Titan's atmosphere and surface.

Quantitative fabrication of functional polymer surfaces

NASA Astrophysics Data System (ADS)

Rengifo, Hernan R.

Polymeric surfaces and films have very broad applications in industry. They have been employed as anticorrosive, abrasive and decorative coatings for many years. More recently, the applications of functional polymer films in microelectronics, optics, nanocomposites, DNA microarrays, and enzyme immobilizations has drawn a lot of attention. There are a number of challenges associated with the implementation of functional polymeric surfaces, and these challenges are especially important in the field of surface modification. In this thesis, three different challenges in the field of polymeric functional surfaces are addressed: first of all, a set of rules for the molecular design are presented in chapters 3 and 4 according to the surface needs. Second, some latent energy source must be incorporated into the material design to quantitative modify a surface. Third, the morphology of the surface, the method use to fabricate the design surface and their new applications are presented in chapters 4 and 5. The new polymeric surface functionalization method described in Chapter 3 is based upon an end-functionalized diblock copolymer design to self-assemble at the surface of both hard and soft surfaces. It is demonstrated that alkyne end-functional diblock copolymers can be used to provide precise control over areal densities of reactive functionality. The areal density of alkyne functional groups is precisely controlled by adjusting the thickness of the block copolymer monolayer, which is accomplished by changing either the spin coating conditions (i.e., rotational speed and solution concentration) or the copolymer molecular weight. The modified surfaces are characterized by atomic force microscopy (AFM), contact angle, ellipsometry, fluorescent imaging and angle-dependent X-ray photoelectron spectroscopy (ADXPS) measurements. In Chapter 4, a simple means is demonstrated to covalently bond DNA to polymer-modified substrates; the method provides quantitative control of the DNA areal density. The approach is based upon synthesis of an alkyne-end-functional diblock copolymer alpha-alkyne-o-Br-poly(tBA- b-MMA). The block copolymer self-assembles to form a bilayer on the substrate and directs alkyne groups to the surface. Azido-functionalized DNA is immobilized on alkyne functionalized substrates by a "click" reaction. The density of immobilized DNA can be quantitatively controlled by varying the parameters used for spin-coating the polymer film or by adjusting the hydrophilicity of the polymer surface underlying the reactive alkyne functional groups. In Chapter 5, Layer by layer (LbL) assembly techniques construct multilayer thin films by sequential deposition of monomolecular layers of organic molecules. One of the drawbacks associated with their use is that monomolecular layers are usually held together by relatively weak forces such as Van der Waals, electrostatic and hydrogen bonding interactions, and can therefore be lacking in mechanical integrity. In this chapter, it is demonstrated that heterobifunctional polymers, functionalized with one azide chain terminus and a protected alkyne group as the other chain terminus, constitute a powerful and versatile means for the covalent layer-by-layer (CLbL) assembly of thin polymer films. Each monomolecular polymer layer is covalently bound to both the preceding and following layers to produce a robust multilayer structure. Because the coupling chemistry used, "click" chemistry, is highly chemoselective, the layering process is virtually independent of the chemical nature of the polymer so that the constitution of each layer can be selected at will. Unlike other layer-by-layer deposition techniques, the layer thickness in CLbL is not equivalent to the diameter of the polymer chain, but is related to the polymer chain length and can be controlled by adjustment of either the polymer molecular weight or the areal density of surface alkyne groups.

High energy density supercapacitors from lignin derived submicron activated carbon fibers in aqueous electrolytes

NASA Astrophysics Data System (ADS)

Hu, Sixiao; Zhang, Sanliang; Pan, Ning; Hsieh, You-Lo

2014-12-01

Highly porous submicron activated carbon fibers (ACFs) were robustly generated from low sulfonated alkali lignin and fabricated into supercapacitors for capacitive energy storage. The hydrophilic and high specific surface ACFs exhibited large-size nanographites and good electrical conductivity to demonstrate outstanding electrochemical performance. ACFs from KOH activation, in particular, showed very high 344 F g-1 specific capacitance at low 1.8 mg cm-2 mass loading and 10 mV s-1 scan rate in aqueous electrolytes. Even at relatively high scan rate of 50 mV s-1 and mass loading of 10 mg cm-2, a decent specific capacitance of 196 F g-1 and a remarkable areal capacitance of 0.55 F cm-2 was obtained, leading to high energy density of 8.1 Wh kg-1 based on averaged electrodes mass. Furthermore, over 96% capacitance retention rates were achieved after 5000 charge/discharge cycles. Such excellent performance demonstrated great potential of lignin derived carbons for electrical energy storage.

(U) An Analytic Study of Piezoelectric Ejecta Mass Measurements

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

Tregillis, Ian Lee

2017-02-16

We consider the piezoelectric measurement of the areal mass of an ejecta cloud, for the specific case where ejecta are created by a single shock at the free surface and fly ballistically through vacuum to the sensor. To do so, we define time- and velocity-dependent ejecta “areal mass functions” at the source and sensor in terms of typically unknown distribution functions for the ejecta particles. Next, we derive an equation governing the relationship between the areal mass function at the source (which resides in the rest frame of the free surface) and at the sensor (which resides in the laboratorymore » frame). We also derive expressions for the analytic (“true”) accumulated ejecta mass at the sensor and the measured (“inferred”) value obtained via the standard method for analyzing piezoelectric voltage traces. This approach enables us to derive an exact expression for the error imposed upon a piezoelectric ejecta mass measurement (in a perfect system) by the assumption of instantaneous creation. We verify that when the ejecta are created instantaneously (i.e., when the time dependence is a delta function), the piezoelectric inference method exactly reproduces the correct result. When creation is not instantaneous, the standard piezo analysis will always overestimate the true mass. However, the error is generally quite small (less than several percent) for most reasonable velocity and time dependences. In some cases, errors exceeding 10-15% may require velocity distributions or ejecta production timescales inconsistent with experimental observations. These results are demonstrated rigorously with numerous analytic test problems.« less

Topographic and Stochastic Influences on Pahoehoe Lava Lobe Emplacement

NASA Technical Reports Server (NTRS)

Hamilton, Christopher W.; Glaze, Lori S.; James, Mike R.; Baloga, Stephen M.

2013-01-01

A detailed understanding of pahoehoe emplacement is necessary for developing accurate models of flow field development, assessing hazards, and interpreting the significance of lava morphology on Earth and other planetary surfaces. Active pahoehoe lobes on Kilauea Volcano, Hawaii, were examined on 21-26 February 2006 using oblique time-series stereo-photogrammetry and differential global positioning system (DGPS) measurements. During this time, the local discharge rate for peripheral lava lobes was generally constant at 0.0061 +/- 0.0019 m3/s, but the areal coverage rate of the lobes exhibited a periodic increase every 4.13 +/- 0.64 minutes. This periodicity is attributed to the time required for the pressure within the liquid lava core to exceed the cooling induced strength of its margins. The pahoehoe flow advanced through a series of down slope and cross-slope breakouts, which began as approximately 0.2 m-thick units (i.e., toes) that coalesced and inflated to become approximately meter-thick lobes. The lobes were thickest above the lowest points of the initial topography and above shallow to reverse facing slopes, defined relative to the local flow direction. The flow path was typically controlled by high-standing topography, with the zone directly adjacent to the final lobe margin having an average relief that was a few centimeters higher than the lava inundated region. This suggests that toe-scale topography can, at least temporarily, exert strong controls on pahoehoe flow paths by impeding the lateral spreading of the lobe. Observed cycles of enhanced areal spreading and inflated lobe morphology are also explored using a model that considers the statistical likelihood of sequential breakouts from active flow margins and the effects of topographic barriers.

Differences Between Surface Ice Deposits at the Poles of Mercury and the Moon: Insights into Ages of the Ice

NASA Astrophysics Data System (ADS)

Deutsch, A. N.; Head, J. W.; Neumann, G. A.

2018-05-01

The poles of Mercury and the Moon both show evidence for water ice, but the deposits on Mercury have a greater areal distribution and a more pure concentration. We explore how these differences may be related to the ages of the ice.

Uncertainty in countrywide forest biomass estimates.

Treesearch

C.E. Peterson; D. Turner

1994-01-01

Country-wide estimates of forest biomass are the major driver for estimating and understanding carbon pools and flux, a critical component of global change research. Important determinants in making these estimates include the areal extent of forested lands and their associated biomass. Estimates for these parameters may be derived from surface-based data, photo...

Facile Synthesis of Mixed Metal Organic Frameworks: Electrode Materials for Supercapacitor with Excellent Areal Capacitance and Operational Stability.

PubMed

Kazemi, Sayed Habib; Hosseinzadeh, Batoul; Kazemi, Hojjat; Kiani, Mohammad Ali; Hajati, Shaaker

2018-06-08

Electrode materials with high surface area, tailored pore size and efficient capability for ion insertion and enhanced transport of electrons and ions are needed for advanced supercapacitors. In the present study, a mixed metal organic framework (cobalt and manganese based MOF) was synthesized through a simple one pot solvothermal method and employed as the electrode material for supercapacitor. Notably, Co-Mn MOF electrode displayed a large surface area and excellent cycling stability (over 95% capacitance retention after 1500 cycles). Also, superior pseudocapacitive behavior was observed for Co-Mn MOF electrode in KOH electrolyte with an exceptional areal capacitance of 1.318 F cm-2. Moreover, an asymmetric supercapacitor was assembled using Co-Mn MOF and activated carbon electrode as positive and negative electrodes, respectively. The fabricated supercapacitor showed specific capacitances of 106.7 F g-1 at a scan rate of 10 mV s-1 and delivered maximum energy density of 30 Wh kg-1 at 2285.7 W kg-1. Our studies suggest the Co-Mn MOF as promising electrode materials for supercapacitor applications.

Study on chemical hydrography, chlorophyll-a and primary productivity in Liaodong Bay, China

NASA Astrophysics Data System (ADS)

Pei, Shaofeng; Laws, Edward A.; Zhang, Haibo; Ye, Siyuan; Kemper, Marc T.; Yuan, Hongming; Xu, Gang; Yang, Shixiong; Liu, Haiyue; Zhu, Yaxuan

2018-03-01

A field study was carried out during the summer of 2013 in Liaodong Bay, China to determine the dynamics of the phytoplankton in the bay and the extent to which primary production in the bay was constrained by environmental factors. There was little or no evidence of limitation of phytoplankton production by nutrient concentrations at any of the sampling stations, with the possible exception of a few offshore stations where phosphate concentrations were less than 30 nM. This assessment was consistent with the results of nutrient enrichment experiments and the values of light-saturated photosynthetic rates and areal photosynthetic rates. To examine the effects of irradiance and temperature on light-saturated photosynthetic rates normalized to chlorophyll a concentrations (Poptb) at twelve stations where photosynthetic rates were measured by 14C method, light-conditioned values were modeled as a function of the temperature with a satisfactory fit to our field data (R2 = 0.60, p = 0.003). According to this model, the light-conditioned Poptb values increased with temperatures from 22 °C to roughly 25 °C but declined precipitously at higher temperatures, and Poptb values and corresponding areal photosynthetic rates at all 66 stations were estimated to be 7.6 ± 2.4 g C g-1 Chl a h-1 and 532 ± 429 gC m-2 d-1 in average, respectively. The quanta absorbed per carbon atom fixed averaged 14 ± 2 and 37 ± 10 at six coastal stations and six estuarine stations, respectively. The relatively high Poptb values and low quantum requirements at the coastal stations implied the highly efficient usage of absorbed light by phytoplankton under nutrient-replete conditions and favorable temperatures. Comparatively, the low Poptb values and high quantum requirements at the estuarine stations suggested rather extreme light limitation and lowly efficient usage of absorbed light in photosynthesis in the Liaohe River estuary. Areal production in Liaodong Bay appears to be controlled by a combination of temperature and light limitation.

Primary production in the tropical continental shelf seas bordering northern Australia

NASA Astrophysics Data System (ADS)

Furnas, Miles J.; Carpenter, Edward J.

2016-10-01

Pelagic primary production (14C uptake) was measured 81 times between 1990 and 2013 at sites spanning the broad, shallow Northern Australian Shelf (NAS; 120-145°E) which borders the Australian continent. The mean of all areal production measurements was 1048±109 mg C m-2 d-1 (mean±95% CI). Estimates of areal primary production were correlated with integral upper-euphotic zone chlorophyll stocks (above the 50% and 20% light penetration depths) accessible to ocean color remote sensing and total water column chlorophyll standing crop, but not surface (0-2 m) chlorophyll concentrations. While the NAS is subject to a well characterized monsoonal climate regime (austral summer-NW monsoon -wet: austral winter- SE monsoon -dry), most seasonal differences in means of regional-scale chlorophyll standing crop (11-33 mg Chl m-2 for 12 of 15 season-region combinations) and areal primary production (700-1850 mg C m- day-1 for 12 of 15 season-region combinations) fell within a 3-fold range. Apart from the shallow waters of the Torres Strait and northern Great Barrier Reef, picoplankton (<2 μm size fraction) dominated chlorophyll standing crop and primary production with regional means of picoplankton contributions ranging from 45 to >80%. While the range of our post-1990 areal production estimates overlaps the range of production estimates made in NAS waters during 1960-62, the mean of post-1990 estimates is over 2-fold greater. We regard the difference to be due to improvements in production measurement techniques, particularly regarding the reduction of potential metal toxicity and incubations in more realistic light regimes.

Precipitation Estimation from the ARM Distributed Radar Network during the MC3E Campaign

DOE PAGES

Giangrande, Scott E.; Collis, Scott; Theisen, Adam K.; ...

2014-09-12

This study presents radar-based precipitation estimates collected during the two-month DOE ARM - NASA Midlatitude Continental Convective Clouds Experiment (MC3E). Emphasis is on the usefulness of radar observations from the C-band and X-band scanning ARM precipitation radars (CSAPR, XSAPR) for rainfall estimation products to distances within 100 km of the Oklahoma SGP facility. A dense collection of collocated ARM, NASA GPM and nearby surface Oklahoma Mesonet gauge records are consulted to evaluate potential ARM radar-based hourly rainfall products and campaign optimized methods over individual gauge and areal characterizations. Rainfall products are evaluated against the performance of the regional operational NWSmore » NEXRAD S-band radar polarimetric product. Results indicate that the ARM C-band system may achieve similar point and areal-gauge bias and root mean square (rms) error performance to the NEXRAD standard for the variety of MC3E deep convective events sampled when capitalizing on differential phase measurements. The best campaign rainfall performance was achieved when applying radar relations capitalizing on estimates of the specific attenuation from the CSAPR system. The ARM X-band systems only demonstrate solid capabilities as compared to NEXRAD standards for hourly point and areal rainfall accumulations under 10 mm. Here, all methods exhibit a factor of 1.5 to 2.5 reduction in rms errors for areal accumulations over a 15 km2 NASA dense network housing 16 sites having collocated bucket gauges, with the higher error reductions best associated with polarimetric methods.« less

Precipitation Estimation from the ARM Distributed Radar Network during the MC3E Campaign

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

Giangrande, Scott E.; Collis, Scott; Theisen, Adam K.

This study presents radar-based precipitation estimates collected during the two-month DOE ARM - NASA Midlatitude Continental Convective Clouds Experiment (MC3E). Emphasis is on the usefulness of radar observations from the C-band and X-band scanning ARM precipitation radars (CSAPR, XSAPR) for rainfall estimation products to distances within 100 km of the Oklahoma SGP facility. A dense collection of collocated ARM, NASA GPM and nearby surface Oklahoma Mesonet gauge records are consulted to evaluate potential ARM radar-based hourly rainfall products and campaign optimized methods over individual gauge and areal characterizations. Rainfall products are evaluated against the performance of the regional operational NWSmore » NEXRAD S-band radar polarimetric product. Results indicate that the ARM C-band system may achieve similar point and areal-gauge bias and root mean square (rms) error performance to the NEXRAD standard for the variety of MC3E deep convective events sampled when capitalizing on differential phase measurements. The best campaign rainfall performance was achieved when applying radar relations capitalizing on estimates of the specific attenuation from the CSAPR system. The ARM X-band systems only demonstrate solid capabilities as compared to NEXRAD standards for hourly point and areal rainfall accumulations under 10 mm. Here, all methods exhibit a factor of 1.5 to 2.5 reduction in rms errors for areal accumulations over a 15 km2 NASA dense network housing 16 sites having collocated bucket gauges, with the higher error reductions best associated with polarimetric methods.« less

A flexible tactile sensitive sheet using a hetero-core fiber optic sensor

NASA Astrophysics Data System (ADS)

Fujino, S.; Yamazaki, H.; Hosoki, A.; Watanabe, K.

2014-05-01

In this report, we have designed a tactile sensitive sheet based on a hetero-core fiber-optic sensor, which realize an areal sensing by using single sensor potion in one optical fiber line. Recently, flexible and wide-area tactile sensing technology is expected to applied to acquired biological information in living space and robot achieve long-term care services such as welfare and nursing-care and humanoid technology. A hetero-core fiber-optic sensor has several advantages such as thin and flexible transmission line, immunity to EMI. Additionally this sensor is sensitive to moderate bending actions with optical loss changes and is independent of temperature fluctuation. Thus, the hetero-core fiber-optic sensor can be suitable for areal tactile sensing. We measure pressure characteristic of the proposed sensitive sheet by changing the pressure position and pinching characteristic on the surface. The proposed tactile sensitive sheet shows monotonic responses on the whole sensitive sheet surface although different sensitivity by the position is observed at the sensitive sheet surface. Moreover, the tactile sensitive sheet could sufficiently detect the pinching motion. In addition, in order to realize the discrimination between pressure and pinch, we fabricated a doubled-over sensor using a set of tactile sensitive sheets, which has different kinds of silicon robbers as a sensitive sheet surface. In conclusion, the flexible material could be given to the tactile sensation which is attached under proposed sensitive sheet.

Simulation study of poled low-water ionomers with different architectures

NASA Astrophysics Data System (ADS)

Allahyarov, Elshad; Taylor, Philip L.; Löwen, Hartmut

2011-11-01

The role of the ionomer architecture in the formation of ordered structures in poled membranes is investigated by molecular dynamics computer simulations. It is shown that the length of the sidechain Ls controls both the areal density of cylindrical aggregates Nc and the diameter of these cylinders in the poled membrane. The backbone segment length Lb tunes the average diameter Ds of cylindrical clusters and the average number of sulfonates Ns in each cluster. A simple empirical formula is noted for the dependence of the number density of induced rod-like aggregates on the sidechain length Ls within the parameter range considered in this study.

Radiative transfer in shrub savanna sites in Niger: Preliminary results from HAPEX-Sahel. Part 1: Modelling surface reflectance using a geometric-optical approach

NASA Technical Reports Server (NTRS)

Franklin, Janet; Duncan, Jeff; Huete, Alfredo R.; vanLeeuwen, W. J. D.; Li, Xiaowen; Begue, Agnes

1994-01-01

To use optical remote sensing to monitor land surface-climate interactions over large areas, algorithms must be developed to relate multispectral measurements to key variables controlling the exchange of matter (water, carbon dioxide) and energy between the land surface and the atmosphere. The proportion of the ground covered by vegetation and the interception of photosynthetically active radiation (PAR) by vegetation are examples of two variables related to evapotranspiration and primary production, respectively. An areal-proportion model of the multispectral reflectance of shrub savanna, composed of scattered shrubs with a grass, forb or soil understory, predicted the reflectance of two 0.5 km(exp 2) sites as the area-weighted average of the shrub and understory or 'background' reflectances. Although the shaded crown and shaded background have darker reflectances, ignoring them in the area-weighted model is not serious when shrub cover is low and solar zenith angle is small. A submodel predicted the reflectance of the shrub crown as a function of the foliage reflectance and amount of plant material within the crown, and the background reflectance scattered or transmitted through canopy gaps (referred to as a soil-plant 'spectral interaction' term). One may be able to combine these two models to estimate both the fraction of vegetation cover and interception of PAR by green vegetation in a shrub savanna.

Enhanced Ge/Si(001) island areal density and self-organization due to P predeposition

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

Cho, B.; Bareno, J.; Petrov, I.

The predeposition of P, with coverages {theta}{sub P} ranging from 0 to 1 ML, on Si(001) significantly increases both the areal density and spatial self-organization of Ge islands grown by gas-source molecular beam epitaxy from hydride precursors. The Ge island density {rho}{sub Ge} initially increases with {theta}{sub P}, reaching a maximum of 1.4 x 10{sup 10} cm{sup -2} at {theta}{sub P} = 0.7 ML, a factor of four times higher than on bare Si(001) under the same deposition conditions, before decreasing at higher P coverages. The increase in {rho}{sub Ge}({theta}{sub P}) is due to a corresponding decrease in Ge adatommore » mean free paths resulting from passivation of surface dangling bonds by adsorbed pentavalent P atoms which, in addition, leads to surface roughening and, therefore, higher Ge coverages at constant Ge{sub 2}H{sub 6} dose. As {theta}{sub P} (and hence, {rho}{sub Ge}) increases, so does the degree of Ge island ordering along <100> directions due to the anisotropic strain field surrounding individual islands. Similar results are obtained for Ge island growth on P-doped Si(001) layers where strong P surface segregation provides partial monolayer coverage prior to Ge deposition.« less

Effects of underground mining and mine collapse on the hydrology of selected basins in West Virginia

USGS Publications Warehouse

Hobba, William A.

1993-01-01

The effects of underground mining and mine collapse on areal hydrology were determined at one site where the mined bed of coal lies above major streams and at two sites where the bed of coal lies below major streams. Subsidence cracks observed at land surface generally run parallel to predominant joint sets in the rocks. The mining and subsidence cracks increase hydraulic conductivity and interconnection of water-bearing rock units, which in turn cause increased infiltration of precipitation and surface water, decreased evapotranspiration, and higher base flows in some small streams. Water levels in observation wells in mined areas fluctuate as much as 100 ft annually. Both gaining and losing streams are found in mined areas. Mine pumpage and drainage can cause diversion of water underground from one basin to another. Areal and single-well aquifer tests indicated that near-surface rocks have higher transmissivity in a mine-subsided basin than in unmined basins. Increased infiltration and circulation through shallow subsurface rocks increase dissolved mineral loads in streams, as do treated and untreated contributions from mine pumpage and drainage. Abandoned and flooded underground mines make good reservoirs because of their increased transmissivity and storage. Subsidence cracks were not detectable by thermal imagery, but springs and seeps were detectable.

Full-wafer fabrication by nanostencil lithography of micro/nanomechanical mass sensors monolithically integrated with CMOS.

PubMed

Arcamone, J; van den Boogaart, M A F; Serra-Graells, F; Fraxedas, J; Brugger, J; Pérez-Murano, F

2008-07-30

Wafer-scale nanostencil lithography (nSL) is used to define several types of silicon mechanical resonators, whose dimensions range from 20 µm down to 200 nm, monolithically integrated with CMOS circuits. We demonstrate the simultaneous patterning by nSL of ∼2000 nanodevices per wafer by post-processing standard CMOS substrates using one single metal evaporation, pattern transfer to silicon and subsequent etch of the sacrificial layer. Resonance frequencies in the MHz range were measured in air and vacuum. As proof-of-concept towards an application as high performance sensors, CMOS integrated nano/micromechanical resonators are successfully implemented as ultra-sensitive areal mass sensors. These devices demonstrate the ability to monitor the deposition of gold layers whose average thickness is smaller than a monolayer. Their areal mass sensitivity is in the range of 10(-11) g cm(-2) Hz(-1), and their thickness resolution corresponds to approximately a thousandth of a monolayer.

Mammoth ecosystem: Climatic areal, animal's density and cause of extinctions

NASA Astrophysics Data System (ADS)

Zimov, S.; Zimov, N.; Zimova, G.; Chapin, S. F.

2008-12-01

During the last glaciations Mammoth Ecosystem (ME) occupied territory from present-day France to Canada and from the Arctic islands to China. This ecosystem played major role in global carbon cycle and human settling around the planet. Causes of extinction of this ecosystem are debatable. Analyses of hundreds of radiocarbon dates of ME animal fossil remains showed that warming and moistening of climate wasn't accompanied by animal extinction. On the opposite, on the north right after the warming rise of herbivore population was observed. Reconstruction of ME climatic areal showed that its climatic optimum lies within range of annual precipitation of 200-350 mm and average summer temperatures of +8-+12oC which corresponds with modern climate of Northern Siberia. Analyses of bones and skeletons concentrations in permafrost of Northern Siberia showed that animal density in ME was similar to African savannah. That was a high productive ecosystem that could sustain in wide variety of climates because numerous herbivores maintained there pastures themselves.

Base-flow characteristics of streams in the Valley and Ridge, Blue Ridge, and Piedmont physiographic provinces of Virginia

USGS Publications Warehouse

Nelms, D.L.; Harlow, G.E.; Hayes, Donald C.

1995-01-01

Growth within the Valley and Ridge, Blue Ridge, and Piedmont Physiographic Provinces of Virginia has focussed concern about allocation of surface-water flow and increased demands on the ground-water resources. The purpose of this report is to (1) describe the base-flow characteristics of streams, (2) identify regional differences in these flow characteristics, and (3) describe, if possible, the potential surface-water and ground-water yields of basins on the basis of the base-flow character- istics. Base-flow characteristics are presented for streams in the Valley and Ridge, Blue Ridge, and Piedmont Physiographic Provinces of Virginia. The provinces are separated into five regions: (1) Valley and Ridge, (2) Blue Ridge, (3) Piedmont/Blue Ridge transition, (4) Piedmont northern, and (5) Piedmont southern. Different flow statistics, which represent streamflows predominantly comprised of base flow, were determined for 217 continuous-record streamflow-gaging stations from historical mean daily discharge and for 192 partial-record streamflow-gaging stations by means of correlation of discharge measurements. Variability of base flow is represented by a duration ratio developed during this investigation. Effective recharge rates were also calculated. Median values for the different flow statistics range from 0.05 cubic foot per second per square mile for the 90-percent discharge on the streamflow-duration curve to 0.61 cubic foot per second per square mile for mean base flow. An excellent estimator of mean base flow for the Piedmont/Blue Ridge transition region and Piedmont southern region is the 50-percent discharge on the streamflow-duration curve, but tends to under- estimate mean base flow for the remaining regions. The base-flow variability index ranges from 0.07 to 2.27, with a median value of 0.55. Effective recharge rates range from 0.07 to 33.07 inches per year, with a median value of 8.32 inches per year. Differences in the base-flow characteristics exist between regions. The median discharges for the Valley and Ridge, Blue Ridge, and Piedmont/Blue Ridge transition regions are higher than those for the Piedmont regions. Results from statistical analysis indicate that the regions can be ranked in terms of base-flow characteristics from highest to lowest as follows: (1) Piedmont/Blue Ridge transition, (2) Valley and Ridge and Blue Ridge, (3) Piedmont southern, and (4) Piedmont northern. The flow statistics are consistently higher and the values for base-flow variability are lower for basins within the Piedmont/Blue Ridge transition region relative to those from the other regions, whereas the basins within the Piedmont northern region show the opposite pattern. The group rankings of the base-flow characteristics were used to designate the potential surface-water yield for the regions. In addition, an approach developed for this investigation assigns a rank for potential surface- water yield to a basin according to the quartiles in which the values for the base-flow character- istics are located. Both procedures indicate that the Valley and Ridge, Blue Ridge, and Piedmont/Blue Ridge transition regions have moderate-to-high potential surface-water yield and the Piedmont regions have low-to-moderate potential surface- water yield. In order to indicate potential ground-water yield from base-flow characteristics, aquifer properties for 51 streamflow-gaging stations with continuous record of streamflow data were determined by methods that use streamflow records and basin characteristics. Areal diffusivity ranges from 17,100 to 88,400 feet squared per day, with a median value of 38,400 feet squared per day. Areal transmissivity ranges from 63 to 830 feet squared per day, with a median value of 270 feet squared per day. Storage coefficients, which were estimated by dividing areal transmissivity by areal diffusivity, range from approximately 0.001 to 0.019 (dimensionless), with a median value of 0.007. The median value for areal diffus

Simulated ground-water flow and sources of water in the Killbuck Creek Valley near Wooster, Wayne County, Ohio

USGS Publications Warehouse

Breen, K.J.; Kontis, A.L.; Rowe, G.L.; Haefner, R.J.

1995-01-01

The stratified-drift aquifer in the 3,000-ft (feet)-wide and 100-ft-deep buried valley of Killbuck Creek near Wooster in northeastern Ohio was studied. The stratified drift with adjacent sandstone and shale bedrock produce a system of ground-water flow representative of the western part of the glaciated north-eastern United States. The stratified-drift aquifer is an excellent source of water for municipal and industrial wells. The aquifer is recharged locally by water from precipitation on the valley floor and uplands, by infiltration from streams, and by lateral flow to the valley from the uplands. As a result, the aquifer is vulnerable to surface or subsurface spills of contaminants in the valley or the adjacent uplands. Quality of water in the stratified drift is affected by influx of water from bedrock lateral to or beneath the valley. This influx is controlled, in part, by the pumping stress placed on the stratified-drift aquifer. Hydrogeologic and aqueous-geochemical data were analyzed to establish the framework necessary for stead-state and transient simulations of ground-water flow in stratified drift and bedrock with a three-layer ground-water-flow model. A new model routine, the Variable-Recharge procedure, was developed to simulate areal recharge and the contribution of the uplands to the drift system. This procedure allows for water applied to land surface to infiltrate or to be rejected. Rejected recharge and ground water discharged when the water table is at land surface form surface runoff-this excess upland water can be redirected as runoff to other parts of the model. Infiltration of streamwater, areal recharge to uplands and valley, and lateral subsurface flow from the uplands to the valley are sources of water to the stratufued0druft aquifer. Water is removed from the stratified-drift aquifer at Wooster primarily by production wells pumping at a rate of approximately 8.5 ft3/s (cubic feet per second). The ground-water budget resulting from two types of simulations of ground-water flow in this study indicates the primary sources of water to the wells are recharge at or near land surface and lateral subsurface flow from the shale and sandstone bedrock. Components of recharge at land surface include induced infiltration from streams, precipitation on the valley floor, and infiltration of unchanneled upland runoff that reaches the valley floor. The steady-state simulation was designed to represent conditions during the fall of 1984. The transient simulation was designed to represent an 11-day snowmelt event, 23 February to 5 March 1985, that caused water levels to rise significantly throughout the valley. Areal recharge to the valley and flow from the uplands to the valley were determined through the Variable-Recharge procedure. The total steady-state recharge to the valley was 12.5 ft3/s. Upland sources, areal valley recharge, and induced infiltration from Killnuck Creek accounted for 63, 23, and 8 percent, respectively, of the valley recharge. An analysis of the simulated vertical flow to the buried stratified drift through surficial slit, clay, and fine sand indicates that about 75 percent of the total recharge to the buried deposits is the sum of areally extensive, relatively small flows less than about 0.01 ft? /s per model node), whereas about 25 percent of the recharge results from a really restricted, relatively large flows (greater than about 0.01 ft? /s per model node). The large-magnitude flows are located primarily beneath Clear and Little Killbuck Creeks where seepage provides abundant recharge and the surficial sediments grade into coarser alluvial-fan deposits. Chemical and isotopic studies of ground water and streamwater combined with measurements of stream infiltration provide independent support for the conclusions derived from computer simulation of ground-water flow. In addition, the chemical and isotopic studies helped quantity the rate and pathways of infiltrating water from

Areally Extensive Surface Bedrock Exposures on Mars: Many Are Clastic Rocks, Not Lavas

NASA Astrophysics Data System (ADS)

Rogers, A. Deanne; Warner, Nicholas H.; Golombek, Matthew P.; Head, James W.; Cowart, Justin C.

2018-02-01

Areally extensive exposures of intact olivine/pyroxene-enriched rock, as well as feldspar-enriched rock, are found in isolated locations throughout the Martian highlands. The petrogenetic origin(s) of these rock units are not well understood, but some previous studies favored an effusive volcanic origin partly on the basis of distinctive composition and relatively high thermal inertia. Here we show that the regolith development, crater retention, and morphological characteristics for many of these "bedrock plains" are not consistent with competent lavas and reinterpret the high thermal inertia orbital signatures to represent friable materials that are more easily kept free of comminution products through eolian activity. Candidate origins include pyroclastic rocks, impact-generated materials, or detrital sedimentary rocks. Olivine/pyroxene enrichments in bedrock plains relative to surrounding materials could have potentially formed through deflation and preferential removal of plagioclase.

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.

Backscattering from frost on icy satellites in the outer solar system

NASA Technical Reports Server (NTRS)

Verbiscer, Anne; Helfenstein, Paul; Veverka, Joseph

1990-01-01

Two extreme models are presented of how frost and ice might be intermixed on a typical satellite surface: areal and intimate mixing. Applying such models to selected representative satellite data, it is found that the frost component of the surfaces of these outer satellites must itself be backscattering, unlike its terrestrial counterpart. The difference may arise because frost particles can have much more complex internal textures under the low-temperature and low-gravity conditions of the outer satellites than is the case on earth.

The Universal Transverse Mercator (UTM) grid

USGS Publications Warehouse

,

1997-01-01

The most convenient way to identify points on the curved surface of the Earth is with a system of reference lines called parallels of latitude and meridians of longitude. On some maps the meridians and parallels appear as straight lines. On most modern maps, however, the meridians and parallels may appear as curved lines. These differences are due to the mathematical treatment required to portray a curved surface on a flat surface so that important properties of the map (such as distance and areal accuracy) are shown with minimum distortion. The system used to portray a portion of the round Earth on a flat surface is called a map projection.

The Universal Transverse Mercator (UTM) grid

USGS Publications Warehouse

,

1999-01-01

The most convenient way to identify points on the curved surface of the Earth is with a system of reference lines called parallels of latitude and meridians of longitude. On some maps, the meridians and parallels appear as straight lines. On most modern maps, however, the meridians and parallels appear as curved lines. These differences sre due to the mathematical treatment required to portray a curved surface on a flat surface so that important properties of the map (such as distance and areal accuracy) are shown with minimum distortion. The system used to portray a portion of the round Earth on a flat surface is called a map projection.

Influence of Surface Properties and Impact Conditions on Adhesion of Insect Residues

NASA Technical Reports Server (NTRS)

Wohl, Christopher J.; Smith, Joseph G.; Connell, John W.; Siochi, Emilie J.; Doss, Jereme R.; Shanahan, Michelle H.; Penner, Ronald K.

2015-01-01

Insect residues can cause premature transition to turbulent flow on laminar flow airfoils. Engineered surfaces that mitigate the adhesion of insect residues provide, therefore, a route to more efficient aerodynamics and reduced fuel burn rates. Areal coverage and heights of residues depend not only on surface properties, but also on impact conditions. We report high speed photography of fruit fly impacts at different angles of inclination on a rigid aluminum surface, optical microscopy and profilometry, and contact angle goniometry to support the design of engineered surfaces. For the polyurethane and epoxy coatings studied, some of which exhibited superhydrophobicity, it was determined that impact angle and surface compositions play critical roles in the efficacy of these surfaces to reduce insect residue adhesion.

Aligned TiO₂ nanotube/nanoparticle heterostructures with enhanced electrochemical performance as three-dimensional anode for lithium-ion microbatteries.

PubMed

Xie, Keyu; Guo, Min; Lu, Wei; Huang, Haitao

2014-11-14

A novel TiO₂ three-dimensional (3D) anode with an aligned TiO₂ nanotube/nanoparticle heterostructure (TiO₂ NTs/NPs) is developed by simply immersing as-anodized TiO₂ NTs into water and further crystallizing the TiO₂ NTs by post-annealing. The heterostructure, with its core in a tubular morphology and with both the outer and inner surface consisting of nanoparticles, is confirmed by FESEM and TEM. A reversible areal capacity of 0.126 mAh · cm(-2) is retained after 50 cycles for the TiO₂ NTs/NPs heterostructure electrode, which is higher than that of the TiO₂ NTs electrode (0.102 mAh · cm(-2) after 50 cycles). At the current densities of 0.02, 0.04, 0.06, 0.08, 0.10 and 0.20 mA · cm(-2), the areal capacities are 0.142, 0.127, 0.117, 0.110, 0.104 and 0.089 mAh · cm(-2), respectively, for the TiO₂ NTs/NPs heterostructure electrode compared to the areal capacities of 0.123, 0.112, 0.105, 0.101, 0.094 and 0.083 mAh · cm(-2), respectively, for the the TiO₂ NTs electrode. The enhanced electrochemical performance is attributed to the unique microstructure of the TiO₂ NTs/NPs heterostructure electrode with the TiO₂ NT core used as a straight pathway for electronic transport and with TiO₂ NP offering enhanced surface areas for facile Li+ insertion/extraction. The results described here inspire a facile approach to fabricate a 3D anode with an enhanced electrochemical performance for lithium-ion microbattery applications.

High Areal Energy 3D-Interdigitated Micro-Supercapacitors in Aqueous and Ionic Liquid Electrolytes

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

Eustache, Etienne; Douard, Camille; Demortière, Arnaud

The fabrication of high performance on-chip 3D micro-supercapacitors (MSCs) based on MnO 2 pseudocapacitive binder-free thin film electrodes (< 500 nm thick) with interdigitated topology is reported. An original technological process easily scalable to pilot production line is proposed on 3-inch silicon wafers. High areal energy (> 10 μWh.cm -2) and power densities (> 10 mW.cm -2) are reached on small footprint micro-supercapacitors (4 mm 2) tested in aqueous electrolyte (0.8 V). Furthermore, the cell voltage of such MSC can be increased up to 1.5 V with EMI TFSI ionic liquids but at the expense of the areal capacitance. Themore » performance in ionic liquid is in the same order of magnitude than the one obtained for aqueous electrolyte. The benefit from the 3D topology is clearly demonstrated when the surface performance are normalized to the electrode thickness allowing to obtain an interesting energy vs power tradeoff (> 10 μWh.cm -2 μm -1 and > 1 mw.cm -2 μm -1). Here, this paper aims at improving the energy density of MSCs while keeping high power capability, by combining the use of ionic liquids and the deposition of MnO 2 thin film onto robust and efficient 3D scaffolds.« less

High Areal Energy 3D-Interdigitated Micro-Supercapacitors in Aqueous and Ionic Liquid Electrolytes

DOE PAGES

Eustache, Etienne; Douard, Camille; Demortière, Arnaud; ...

2017-08-21

The fabrication of high performance on-chip 3D micro-supercapacitors (MSCs) based on MnO 2 pseudocapacitive binder-free thin film electrodes (< 500 nm thick) with interdigitated topology is reported. An original technological process easily scalable to pilot production line is proposed on 3-inch silicon wafers. High areal energy (> 10 μWh.cm -2) and power densities (> 10 mW.cm -2) are reached on small footprint micro-supercapacitors (4 mm 2) tested in aqueous electrolyte (0.8 V). Furthermore, the cell voltage of such MSC can be increased up to 1.5 V with EMI TFSI ionic liquids but at the expense of the areal capacitance. Themore » performance in ionic liquid is in the same order of magnitude than the one obtained for aqueous electrolyte. The benefit from the 3D topology is clearly demonstrated when the surface performance are normalized to the electrode thickness allowing to obtain an interesting energy vs power tradeoff (> 10 μWh.cm -2 μm -1 and > 1 mw.cm -2 μm -1). Here, this paper aims at improving the energy density of MSCs while keeping high power capability, by combining the use of ionic liquids and the deposition of MnO 2 thin film onto robust and efficient 3D scaffolds.« less

Involuntary psychiatric examinations for danger to others in Florida after the attacks of September 11, 2001.

PubMed

Catalano, Ralph A; Kessell, Eric; Christy, Annette; Monahan, John

2005-07-01

Theories of perceived risk state that when people feel threatened, they will react more strongly than they would otherwise. This study tested the hypothesis that evaluations for involuntary psychiatric hospitalizations that were initiated by law enforcement personnel in Florida increased in the weeks after the attacks of September 11, 2001. The authors applied interrupted time-series designs to determine whether there was a relationship between the number of involuntary psychiatric examinations initiated by law enforcement officials and the attacks of September 11, 2001. They examined the number of psychiatric evaluations of men and women who were considered to be mentally ill and harmful to others by law enforcement personnel in Florida during seven-day periods ("areal" weeks) that began with Tuesday, July 6, 1999, and ended with Monday, December 31, 2001 (because September 11, 2001, fell on a Tuesday). Over the 130 weeks of the study, law enforcement officials initiated examinations of an average of 25.96 men and 13.47 women per areal week. Law enforcement officials initiated examinations of approximately 14 more women than expected in the areal week that began with September 11, 2001. During the three areal weeks that began with September 18, 2001, a total of 34 more men than expected were presented for evaluation. These findings cannot be attributed to trends, seasonality, other cycles, or the tendency of the examination time series to remain elevated or depressed after high or low values in the series. Perceived general risk in a community may increase the likelihood that law enforcement personnel and the persons who summon them perceive persons with mental illness as imminently harmful. The public health response to any future terror attacks should include efforts to alert psychiatric service providers to the possibility of lower community tolerance for mental illness in the aftermath of an attack.

Visualizing diurnal population change in urban areas for emergency management.

PubMed

Kobayashi, Tetsuo; Medina, Richard M; Cova, Thomas J

2011-01-01

There is an increasing need for a quick, simple method to represent diurnal population change in metropolitan areas for effective emergency management and risk analysis. Many geographic studies rely on decennial U.S. Census data that assume that urban populations are static in space and time. This has obvious limitations in the context of dynamic geographic problems. The U.S. Department of Transportation publishes population data at the transportation analysis zone level in fifteen-minute increments. This level of spatial and temporal detail allows for improved dynamic population modeling. This article presents a methodology for visualizing and analyzing diurnal population change for metropolitan areas based on this readily available data. Areal interpolation within a geographic information system is used to create twenty-four (one per hour) population surfaces for the larger metropolitan area of Salt Lake County, Utah. The resulting surfaces represent diurnal population change for an average workday and are easily combined to produce an animation that illustrates population dynamics throughout the day. A case study of using the method to visualize population distributions in an emergency management context is provided using two scenarios: a chemical release and a dirty bomb in Salt Lake County. This methodology can be used to address a wide variety of problems in emergency management.

Effects of capillarity and microtopography on wetland specific yield

USGS Publications Warehouse

Sumner, D.M.

2007-01-01

Hydrologic models aid in describing water flows and levels in wetlands. Frequently, these models use a specific yield conceptualization to relate water flows to water level changes. Traditionally, a simple conceptualization of specific yield is used, composed of two constant values for above- and below-surface water levels and neglecting the effects of soil capillarity and land surface microtopography. The effects of capiltarity and microtopography on specific yield were evaluated at three wetland sites in the Florida Everglades. The effect of capillarity on specific yield was incorporated based on the fillable pore space within a soil moisture profile at hydrostatic equilibrium with the water table. The effect of microtopography was based on areal averaging of topographically varying values of specific yield. The results indicate that a more physically-based conceptualization of specific yield incorporating capillary and microtopographic considerations can be substantially different from the traditional two-part conceptualization, and from simpler conceptualizations incorporating only capillarity or only microtopography. For the sites considered, traditional estimates of specific yield could under- or overestimate the more physically based estimates by a factor of two or more. The results suggest that consideration of both capillarity and microtopography is important to the formulation of specific yield in physically based hydrologic models of wetlands. ?? 2007, The Society of Wetland Scientists.

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, Z.; Wang, J.; Ishikawa, H.

2011-05-01

Land surface heat fluxes are essential measures of the strengths of land-atmosphere interactions involving energy, heat and water. Correct parameterization of these fluxes in climate models is critical. Despite their importance, state-of-the-art observation techniques cannot provide representative areal averages of these fluxes comparable to the model grid. Alternative methods of estimation are thus required. These alternative approaches use (satellite) observables of the land surface conditions. In this study, the Surface Energy Balance System (SEBS) algorithm was evaluated in a cold and arid environment, using land surface parameters derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. Field observations and estimates from SEBS were compared in terms of net radiation flux (Rn), soil heat flux (G0), sensible heat flux (H) and latent heat flux (λE) over a heterogeneous land surface. As a case study, this methodology was applied to the experimental area of the Watershed Allied Telemetry Experimental Research (WATER) project, located on the mid-to-upstream sections of the Heihe River in northwest China. ASTER data acquired between 3 May and 4 June 2008, under clear-sky conditions were used to determine the surface fluxes. Ground-based measurements of land surface heat fluxes were compared with values derived from the ASTER data. The results show that the derived surface variables and the land surface heat fluxes furnished by SEBS in different months over the study area are in good agreement with the observed land surface status under the limited cases (some cases looks poor results). So SEBS can be used to estimate turbulent heat fluxes with acceptable accuracy in areas where there is partial vegetation cover in exceptive conditions. It is very important to perform calculations using ground-based observational data for parameterization in SEBS in the future. Nevertheless, the remote-sensing results can provide improved explanations of land surface fluxes over varying land coverage at greater spatial scales.

Validation of Long Bone Mechanical Properties from Densitometry

NASA Technical Reports Server (NTRS)

Whalen, R.; Katz, B.; Cleek, T.; Hargens, Alan R. (Technical Monitor)

1995-01-01

The objective of this study was to assess whether cross-sectional areal properties, calculated from densitometry, correlate to the true flexural properties. Right and left male embalmed tibiae were used in the study. Prior to scanning, the proximal end of each tibia was potted in a fixture with registration pins, flushed thoroughly with water under pressure to remove trapped air, and then placed in a constant thickness water bath attached to a precision indexer. Two sets of three scans of the entire tibia were taken with an Hologic QDR 1000/W densitometer at rotations of 0, 45, and 90 degrees about the tibia long axis. An aluminum step phantom and a bone step phantom, machined from bovine cortical bone, were also in the bath and scanned separately. Pixel attenuation data from the two sets of scans were averaged to reduce noise. Pixel data from the high energy beam were then converted to equivalent thicknesses using calibration equations. Cross-sectional areal properties (centroid, principal area moments and principal angle) along the length were computed from the three registered scans using methods developed in our laboratory. Flexural rigidities. Four strain gages were bonded around the circumference of each of 5 cross-sections encompassing the entire diaphysis. A known transverse load was then applied to the distal end and the bone was rotated 360 degrees in eight increments of 45 degrees each. Strains from the eight orientations were analyzed along with the known applied bending moments at each section to compute section centroids, curvatures, principal flexural rigidities and principal angle. Reference axes between the two methods were maintained within +/- 0.5 degrees using an electronic inclinometer. Principal angles (flexural - areal) differed by -2.0 +/- 4.0 degrees, and 1.0 +/- 2.5 degrees for the right and left tibia, respectively. Section principal flexural rigidities were highly correlated to principal areal moments (right: r(sup 2)= 0.997; left: r(sup 2)= 0.978) indicating a nearly constant effective flexural modulus. Right and left tibia exhibited a very high degree of symmetry when comparing either flexural or areal properties. To our knowledge this is the first study to validate the use of densitometry (DXA) to predict three dimensional structural properties of long bones. Our initial results support the conclusion that bone mineral and its distribution are the primary determinants of flexural modulus and rigidity.

Enabling high areal capacitance in electrochemical double layer capacitors by means of the environmentally friendly starch binder

NASA Astrophysics Data System (ADS)

Varzi, Alberto; Passerini, Stefano

2015-12-01

Potatoes starch (PS), a natural polymer obtainable from non-edible sources, is for the first time evaluated as alternative water-processable binder for Electrochemical Double-Layer Capacitor (EDLC) electrodes. Morphological and electrochemical properties of activated carbon (AC)-based electrodes are investigated and compared to those achieved with the state-of-the-art aqueous binder (CMC, i.e. Na-carboxymethyl cellulose). The obtained results suggest substantial benefits of PS, in particular regarding the electrode fabrication process. As a matter of fact, owing to its amylopectin content (moderately branched polysaccharide), PS displays only minimal shrinkage upon drying, resulting on rather homogeneous electrodes not presenting the dramatic surface cracking observed with CMC. Furthermore, owing to the smaller volume of water required for the processing, much higher active material loading per area unit can be achieved. This is reflected on improvements of up to 60% in terms of areal capacitance.

STS-65 Earth observation of Lake Chad, Africa, taken aboard Columbia, OV-102

NASA Technical Reports Server (NTRS)

1994-01-01

STS-65 Earth observation taken aboard Columbia, Orbiter Vehicle (OV) 102, shows Lake Chad, Africa. This is another long term ecological monitoring site for NASA scientists. Lake Chad was first photographed from space in 1965. A 25-year length-of-record data set exists for this environmentally important area. A number of these scenes have been digitized, rectified, classified and results show that the lake area has been shrinking and only 15% to 20% of the surface water is visible on space images. NASA's objective in monitoring this lake is to document the intra- and interannual areal changes of the largest standing water body in the Sahelian biome of North Africa. These areal changes are an indicator of the presence or absence of drought across the arguably overpopulated, overgrazed, and over biological carrying capacity limits nations of the Sahel.

Diamond-Based Supercapacitors: Realization and Properties.

PubMed

Gao, Fang; Nebel, Christoph E

2016-10-26

In this Spotlight on Applications, we describe our recent progress on the fabrication of surface-enlarged boron-doped polycrystalline diamond electrodes, and evaluate their performance in supercapacitor applications. We begin with a discussion of the fabrication methods of porous diamond materials. The diamond surface enlargement starts with a top-down plasma etching method. Although the extra surface area provided by surface roughening or nanostructuring provides good outcome for sensing applications, a capacitance value <1 mF cm -2 or a surface-enlargement factor <100 fail to meet the requirement of a practical supercapacitor. Driven by the need for large surface areas, we recently focused on the tempated-growth method. We worked on both supported and free-standing porous diamond materials to enhance the areal capacitance to the "mF cm -2 " range. With our newly developed free-standing diamond paper, areal capacitance can be multiplied by stacking multilayers of the electrode material. Finally, considering the fact that there is no real diamond-based supercapacitor device up to now, we fabricated the first prototype pouch-cell device based on the free-standing diamond paper to evaluate its performance. The results reveal that the diamond paper is suitable for operation in high potential windows (up to 2.5 V) in aqueous electrolyte with a capacitance of 0.688 mF cm -2 per layer of paper (or 0.645 F g -1 ). Impedance spectroscopy revealed that the operation frequency of the device exceeds 30 Hz. Because of the large potential window and the ability to work at high frequency, the specific power of the device reached 1 × 10 5 W kg -1 . In the end, we made estimations on the future target performance of diamond supercapacitors based on the existing information.

Surface runoff and tile drainage transport of phosphorus in the midwestern United States.

PubMed

Smith, Douglas R; King, Kevin W; Johnson, Laura; Francesconi, Wendy; Richards, Pete; Baker, Dave; Sharpley, Andrew N

2015-03-01

The midwestern United States offers some of the most productive agricultural soils in the world. Given the cool humid climate, much of the region would not be able to support agriculture without subsurface (tile) drainage because high water tables may damage crops and prevent machinery usage in fields at critical times. Although drainage is designed to remove excess soil water as quickly as possible, it can also rapidly transport agrochemicals, including phosphorus (P). This paper illustrates the potential importance of tile drainage for P transport throughout the midwestern United States. Surface runoff and tile drainage from fields in the St. Joseph River Watershed in northeastern Indiana have been monitored since 2008. Although the traditional concept of tile drainage has been that it slowly removes soil matrix flow, peak tile discharge occurred at the same time as peak surface runoff, which demonstrates a strong surface connection through macropore flow. On our research fields, 49% of soluble P and 48% of total P losses occurred via tile discharge. Edge-of-field soluble P and total P areal loads often exceeded watershed-scale areal loadings from the Maumee River, the primary source of nutrients to the western basin of Lake Erie, where algal blooms have been a pervasive problem for the last 10 yr. As farmers, researchers, and policymakers search for treatments to reduce P loading to surface waters, the present work demonstrates that treating only surface runoff may not be sufficient to reach the goal of 41% reduction in P loading for the Lake Erie Basin. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Source and dispersal of silt on northern Gulf of Mexico continental shelf

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

Peterson, M.; Mazzullo, J.

1988-01-01

The surficial sediment on the continental shelf of the northern Gulf of Mexico is characterized by abundant silty clay which was deposited during the late Pleistocene lowstand and reworked during and after the Holocene transgression. The purposes of this study were to determine the sources of the silt fraction in this surficial sediment by quartz grain roundness and surface texture analysis, and to determine the effects of modern shelf currents upon the distribution of silt. Areal variations in quartz grain roundness and surface texture define six silt provinces on the northern Gulf of Mexico continental shelf. The Mississippi province ismore » the largest province and stretches from the Chandeleur Islands to Matagorda Bay. It is characterized by a mixture of rounded grains that were derived from the sedimentary rocks of the Gulf coastal plain and the Mid-Continent, and angular, fractured grains that were derived from glacial deposits in the northern United States. A comparison of the areal distribution of these six provinces with the late Pleistocene paleogeography of the continental shelf shows evidence for varying degrees of shore-parallel transport of silt by modern shelf currents.« less

Advances in engineering nanometrology at the National Physical Laboratory

NASA Astrophysics Data System (ADS)

Leach, Richard K.; Claverley, James; Giusca, Claudiu; Jones, Christopher W.; Nimishakavi, Lakshmi; Sun, Wenjuan; Tedaldi, Matthew; Yacoot, Andrew

2012-07-01

The National Physical Laboratory, UK, has been active in the field of engineering nanometrology for a number of years. A summary of progress over the last five years is presented in this paper and the following research projects discussed in detail. (1) Development of an infrastructure for the calibration of instruments for measuring areal surface topography, along with the development of areal software measurement standards. This work comprises the use of the optical transfer function and a technique for the simultaneous measurement of topography and the phase change on reflection, allowing composite materials to be measured. (2) Development of a vibrating micro-CMM probe with isotropic probing reaction and the ability to operate in a non-contact mode. (3) A review of x-ray computed tomography and its use in dimensional metrology. (4) The further development of a metrology infrastructure for atomic force microscopy and the development of an instrument for the measurement of the effect of the probe-surface interaction. (5) Traceable measurement of displacement using optical and x-ray interferometry to picometre accuracy. (6) Development of an infrastructure for low-force metrology, including the development of appropriate transfer artefacts.

High areal capacity hybrid magnesium-lithium-ion battery with 99.9% Coulombic efficiency for large-scale energy storage.

PubMed

Yoo, Hyun Deog; Liang, Yanliang; Li, Yifei; Yao, Yan

2015-04-01

Hybrid magnesium-lithium-ion batteries (MLIBs) featuring dendrite-free deposition of Mg anode and Li-intercalation cathode are safe alternatives to Li-ion batteries for large-scale energy storage. Here we report for the first time the excellent stability of a high areal capacity MLIB cell and dendrite-free deposition behavior of Mg under high current density (2 mA cm(-2)). The hybrid cell showed no capacity loss for 100 cycles with Coulombic efficiency as high as 99.9%, whereas the control cell with a Li-metal anode only retained 30% of its original capacity with Coulombic efficiency well below 90%. The use of TiS2 as a cathode enabled the highest specific capacity and one of the best rate performances among reported MLIBs. Postmortem analysis of the cycled cells revealed dendrite-free Mg deposition on a Mg anode surface, while mossy Li dendrites were observed covering the Li surface and penetrated into separators in the Li cell. The energy density of a MLIB could be further improved by developing electrolytes with higher salt concentration and wider electrochemical window, leading to new opportunities for its application in large-scale energy storage.

Areal Control Using Generalized Least Squares As An Alternative to Stratification

Treesearch

Raymond L. Czaplewski

2001-01-01

Stratification for both variance reduction and areal control proliferates the number of strata, which causes small sample sizes in many strata. This might compromise statistical efficiency. Generalized least squares can, in principle, replace stratification for areal control.

Choosing the Optimal Number of B-spline Control Points (Part 1: Methodology and Approximation of Curves)

NASA Astrophysics Data System (ADS)

Harmening, Corinna; Neuner, Hans

2016-09-01

Due to the establishment of terrestrial laser scanner, the analysis strategies in engineering geodesy change from pointwise approaches to areal ones. These areal analysis strategies are commonly built on the modelling of the acquired point clouds. Freeform curves and surfaces like B-spline curves/surfaces are one possible approach to obtain space continuous information. A variety of parameters determines the B-spline's appearance; the B-spline's complexity is mostly determined by the number of control points. Usually, this number of control points is chosen quite arbitrarily by intuitive trial-and-error-procedures. In this paper, the Akaike Information Criterion and the Bayesian Information Criterion are investigated with regard to a justified and reproducible choice of the optimal number of control points of B-spline curves. Additionally, we develop a method which is based on the structural risk minimization of the statistical learning theory. Unlike the Akaike and the Bayesian Information Criteria this method doesn't use the number of parameters as complexity measure of the approximating functions but their Vapnik-Chervonenkis-dimension. Furthermore, it is also valid for non-linear models. Thus, the three methods differ in their target function to be minimized and consequently in their definition of optimality. The present paper will be continued by a second paper dealing with the choice of the optimal number of control points of B-spline surfaces.

Molecular beam epitaxy of InN nanowires on Si

NASA Astrophysics Data System (ADS)

Golam Sarwar, A. T. M.; Carnevale, Santino D.; Kent, Thomas F.; Laskar, Masihhur R.; May, Brelon J.; Myers, Roberto C.

2015-10-01

We report on a systematic growth study of the nucleation process of InN nanowires on Si(1 1 1) substrates using plasma assisted molecular beam epitaxy (PAMBE). Samples are grown with various substrate temperatures and III/V ratios. Scanning electron microscopy, X-ray diffraction spectroscopy, energy dispersive X-ray spectroscopy, and photoluminescence are carried out to map out the variation in structural and optical properties versus growth conditions. Statistical averages of areal density, height, and radius are mapped as a function of substrate temperature and III/V ratio. Three different morphological phases are identified on the growth surface: InN, α-In and β-In. Based on SEM image analysis of samples grown at different conditions, the formation mechanism of these phases is proposed. Finally, the growth phase diagram of PAMBE grown InN on Si under N-rich condition is presented, and tapered versus non-tapered growth conditions are identified. It is found that high growth temperature and low III/V ratio plays a critical role in the growth of non-tapered InN nanowires.

Use of areal snow cover measurements from ERTS-1 imagery in snowmelt-runoff relationships in Arizona

NASA Technical Reports Server (NTRS)

Aul, J. S.; Ffolliott, P. F.

1975-01-01

Methods of interpreting ERTS-1 imagery to measure areal snow cover were analyzed. Relationship of areal snow cover and runoff were among the objectives in this study of ERTS-1 imagery use for forecasting snowmelt-runoff relationships.

Radiostrontium hot spot in the Russian Arctic: ground surface contamination by (90)Sr at the "Kraton-3" underground nuclear explosion site.

PubMed

Ramzaev, Valery; Mishine, Arkady; Basalaeva, Larisa; Brown, Justin

2007-01-01

Strontium-90 activity concentrations in surface soils and areal deposition densities have been studied at a site contaminated by an accidental release to atmosphere from the underground nuclear explosion "Kraton-3" conducted near the Polar Circle (65.9 degrees N, 112.3 degrees E) within the territory of the former USSR in 1978. In 2001-2002, the ground surface contamination at 14 plots studied ranged from 20 to 15 000 kBq m(-2), which significantly exceeds the value of 0.44 kBq m(-2) deduced for three background plots. The zone with substantial radiostrontium contamination extends, at least, 2.5 km in a north-easterly direction from the borehole. The average (137)Cs/(90)Sr ratio in the ground contamination originated from the "Kraton-3" fallout was estimated to be 0.55, which is significantly different from the ratio of 2.05 evaluated for background plots contaminated mostly from global fallout. Although vertical migration of (90)Sr in all undisturbed soil profiles studied is more rapid than that for (137)Cs, the depth of percolation of both radionuclides into the ground is mostly limited to the top 10-20 cm, which may be explained, primarily, by permafrost conditions. The horizontal migration rate of radiostrontium in the aqueous phase exceeds the radiocaesium migration rate by many times. This phenomenon seems to be a reason for the significant enrichment of the soil surface layers by radiostrontium at some sites, with variations occurring in accordance with small-scale irregularities of landscape.

[Relationship between the nitrogen removal and oxygen demand in constructed wetlands].

PubMed

He, Lian-sheng; Liu, Hong-liang; Xi, Bei-dou; Zhu, Ying-bo; Wei, Zi-min; Huo, Shou-liang

2006-06-01

A simplified model of sequential N transformations and sink was applied to investigate the relationship between the nitrogen removal and oxygen demand to verify the validity of full nitrification-denitrification mechanism in a newly-built multi-stages constructed wetlands. Average net rates of N mineralization ranged from 0.01 to 0.28 g x (m2 x d)(-1), nitrification from 0.50 to 1.54 g x (m2 x d)(-1), denitrification from 0.41 to 1.13 g x (m2 x d)(-1)(3.4% approximately 35.4% of measured N removal in different stage) and plant assimilation from 0.07 to 0.26 g x (m2 x d)(-1) in the five tanks. Nitrification and denitrification occurred concurrently with BOD removal, even in the first stage receiving the higher-strength wastewater. Surprisingly, net areal nitrification rates, was correlated with BOD removal rates positively. Nitrification rates were also correlated linearly with average NH4+-N concentrations in the cascade tanks. The nitrogenous oxygen demand (NOD) required to support full nitrification of ammonia and mineralized Org-N in the wetland was in the upper range of that expected to be able to be supplied through surface and plant-mediated oxygen transfer. Some potential alternative nitrogen removal pathways with reduced overall oxygen requirements that have relevance to constructed wetlands were discussed.

Observations of sea ice ridging in the Weddell Sea

NASA Astrophysics Data System (ADS)

Granberg, Hardy B.; Leppaäranta, Matti

1999-11-01

Sea ice surface topography data were obtained by helicopter-borne laser profiling during the First Finnish Antarctic Expedition (FINNARP-89). The measurements were made near the ice margin at about 73°S, 27°W in the eastern Weddell Sea on December 31, 1989, and January 1, 1990. Five transects, ranging in length from 127 to 163 km and covering a total length of 724 km, are analyzed. With a lower cutoff of 0.91 m the overall ridge frequency was 8.4 ridges/km and the average ridge height was 1.32 m. The spatial variations in ridging were large; for 36 individual 20-km segments the frequencies were 2-16 ridges/km and the mean heights were 1.16-1.56 m. The frequencies and mean heights were weakly correlated. The distributions of the ridge heights followed the exponential distribution; the spacings did not pass tests for either the exponential or the lognormal distribution, but the latter was much closer. In the 20-km segments the areally averaged thickness of ridged ice was 0.51±0.28 m, ranging from 0.10 to 1.15 m. The observed ridge size and frequency are greater than those known for the Ross Sea. Compared with the central Arctic, the Weddell Sea ridging frequencies are similar but the ridge heights are smaller, possibly as a result of differences in snow accumulation.

Near-surface Density Currents Observed in the Southeast Pacific Stratocumulus-topped Marine Boundary Layer

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

Wilbanks, Matt C.; Yuter, S. E.; de Szoeke, S.

2015-09-01

Density currents (i.e. cold pools or outflows) beneath marine stratocumulus clouds are characterized using a 30-d data set of ship-based observations obtained during the 2008 Variability of American Monsoon Systems (VAMOS) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) in the southeast Pacific. An objective method identifies 71 density current fronts using an air density criterion and isolates each density current’s core (peak density) and tail (dissipating) zone. Compared to front and core zones, most density current tails exhibited weaker density gradients and wind anomalies elongated about the axis of the mean wind. The mean cloud-level advection relative to the surface layer windmore » (1.9 m s-1) nearly matches the mean density current propagation speed (1.8 m s-1). The similarity in speeds allows drizzle cells to deposit tails in their wakes. Based on high-resolution scanning Doppler lidar data, prefrontal updrafts had a mean intensity of 0.91 m s-1, reached an average altitude of 800 m, and were often surmounted by low-lying shelf clouds not connected to the overlying stratocumulus cloud. Nearly 90% of density currents were identified when C-band radar estimated 30-km diameter areal average rain rates exceeded 1 mm d-1. Rather than peaking when rain rates are highest overnight, density current occurrence peaks between 0600 and 0800 local solar time when enhanced local drizzle co-occurs with shallow subcloud dry and stable layers. The dry layers may contribute to density current formation by enhancing subcloud evaporation of drizzle. Density currents preferentially occur in regions of open cells but also occur in regions of closed cells.« less

Reliability in the location of hindlimb motor representations in Fischer-344 rats: laboratory investigation.

PubMed

Frost, Shawn B; Iliakova, Maria; Dunham, Caleb; Barbay, Scott; Arnold, Paul; Nudo, Randolph J

2013-08-01

The purpose of the present study was to determine the feasibility of using a common laboratory rat strain for reliably locating cortical motor representations of the hindlimb. Intracortical microstimulation techniques were used to derive detailed maps of the hindlimb motor representations in 6 adult Fischer-344 rats. The organization of the hindlimb movement representation, while variable across individual rats in topographic detail, displayed several commonalities. The hindlimb representation was positioned posterior to the forelimb motor representation and posterolateral to the motor trunk representation. The areal extent of the hindlimb representation across the cortical surface averaged 2.00 ± 0.50 mm(2). Superimposing individual maps revealed an overlapping area measuring 0.35 mm(2), indicating that the location of the hindlimb representation can be predicted reliably based on stereotactic coordinates. Across the sample of rats, the hindlimb representation was found 1.25-3.75 mm posterior to the bregma, with an average center location approximately 2.6 mm posterior to the bregma. Likewise, the hindlimb representation was found 1-3.25 mm lateral to the midline, with an average center location approximately 2 mm lateral to the midline. The location of the cortical hindlimb motor representation in Fischer-344 rats can be reliably located based on its stereotactic position posterior to the bregma and lateral to the longitudinal skull suture at midline. The ability to accurately predict the cortical localization of functional hindlimb territories in a rodent model is important, as such animal models are being increasingly used in the development of brain-computer interfaces for restoration of function after spinal cord injury.

Reliability in the Location of Hindlimb Motor Representations in Fischer-344 Rats

PubMed Central

Frost, Shawn B.; Iliakova, Maria; Dunham, Caleb; Barbay, Scott; Arnold, Paul; Nudo, Randolph J.

2014-01-01

Object The purpose of the present study was to determine the feasibility of using a common laboratory rat strain for locating cortical motor representations of the hindlimb reliably. Methods Intracortical Microstimulation (ICMS) techniques were used to derive detailed maps of the hindlimb motor representations in six adult Fischer-344 rats. Results The organization of the hindlimb movement representation, while variable across individuals in topographic detail, displayed several commonalities. The hindlimb representation was positioned posterior to the forelimb motor representation and postero-lateral to the motor trunk representation. The areal extent of the hindlimb representation across the cortical surface averaged 2.00 +/− 0.50 mm2. Superimposing individual maps revealed an overlapping area measuring 0.35 mm2, indicating that the location of the hindlimb representation can be predicted reliably based on stereotactic coordinates. Across the sample of rats, the hindlimb representation was found 1.25–3.75 mm posterior to Bregma, with an average center location ~ 2.6 mm posterior to Bregma. Likewise, the hindlimb representation was found 1–3.25 mm lateral to the midline, with an average center location ~ 2 mm lateral to midline. Conclusions The location of the cortical hindlimb motor representation in Fischer-344 rats can be reliably located based on its stereotactic position posterior to Bregma and lateral to the longitudinal skull suture at midline. The ability to accurately predict the cortical localization of functional hindlimb territories in a rodent model is important, as such animal models are being used increasingly in the development of brain-computer interfaces for restoration of function after spinal cord injury. PMID:23725395

Visualization and Quantitative Analysis of Crack-Tip Plastic Zone in Pure Nickel

NASA Astrophysics Data System (ADS)

Kelton, Randall; Sola, Jalal Fathi; Meletis, Efstathios I.; Huang, Haiying

2018-05-01

Changes in surface morphology have long been thought to be associated with crack propagation in metallic materials. We have studied areal surface texture changes around crack tips in an attempt to understand the correlations between surface texture changes and crack growth behavior. Detailed profiling of the fatigue sample surface was carried out at short fatigue intervals. An image processing algorithm was developed to calculate the surface texture changes. Quantitative analysis of the crack-tip plastic zone, crack-arrested sites near triple points, and large surface texture changes associated with crack release from arrested locations was carried out. The results indicate that surface texture imaging enables visualization of the development of plastic deformation around a crack tip. Quantitative analysis of the surface texture changes reveals the effects of local microstructures on the crack growth behavior.

Analyzing the Potential for Unmanned Aerial Systems (UAS) Photogrammetry in Estimating Surface Deformations at a Geothermal Fiel

NASA Astrophysics Data System (ADS)

Pai, H.; Burnett, J.; Sladek, C.; Wing, M.; Feigl, K. L.; Selker, J. S.; Tyler, S.; Team, P.

2016-12-01

UAS systems equipped with a variety of spectral imaging devices are increasingly incorporated in spatial environmental assessments of continental surfaces (e.g., digital elevation maps, vegetative coverage classifications, surface temperatures). This presented work performed by the UAS team at the Center for Transformative Environmental Monitoring Programs (AirCTEMPS) examines the potential to measure small (sub-cm) deformation from a geothermal injection experiment at Brady's geothermal field in western Nevada (USA). Areal mapping of the 700 x 270 m area of interest was conducted with a nadir pointing Sony A5100 digital camera onboard an autopiloted quadcopter. A total of 16 ground control points were installed using a TopCon GR3 GPS receiver. Two such mapping campaigns were conducted with one before and one after an anticipated surface deformation event. A digital elevation map (DEM) for each time period was created from over 1500 images having 80% overlap/sidelap by using structure from motion (SfM) via Agisoft Photoscan software. The resulting DEM resolution was 8 mm/pixel with residual aerial triangulation errors was < 5 mm. We present preliminary results from an optimized workflow which achieved errors and average differential DEM heights between campaigns at the cm-scale which is broader than the maximum expected deformation. Despite the disconnect between error and deformation severity, this study presents a unique application of sub-cm UAS-based DEMs and further distinguishes itself by comparing results to concurrent Interferometric Synthetic Radar (InSAR). The intent of our study and presentation of results is to streamline, cross-validate, and share methods to encourage further adoption of UAS imagery into the standard toolkit for environmental surface sensing across spatial scales.

The areal reduction factor: A new analytical expression for the Lazio Region in central Italy

NASA Astrophysics Data System (ADS)

Mineo, C.; Ridolfi, E.; Napolitano, F.; Russo, F.

2018-05-01

For the study and modeling of hydrological phenomena, both in urban and rural areas, a proper estimation of the areal reduction factor (ARF) is crucial. In this paper, we estimated the ARF from observed rainfall data as the ratio between the average rainfall occurring in a specific area and the point rainfall. Then, we compared the obtained ARF values with some of the most widespread empirical approaches in literature which are used when rainfall observations are not available. Results highlight that the literature formulations can lead to a substantial over- or underestimation of the ARF estimated from observed data. These findings can have severe consequences, especially in the design of hydraulic structures where empirical formulations are extensively applied. The aim of this paper is to present a new analytical relationship with an explicit dependence on the rainfall duration and area that can better represent the ARF-area trend over the area case of study. The analytical curve presented here can find an important application to estimate the ARF values for design purposes. The test study area is the Lazio Region (central Italy).

Misclassification bias in areal estimates

Treesearch

Raymond L. Czaplewski

1992-01-01

In addition to thematic maps, remote sensing provides estimates of area in different thematic categories. Areal estimates are frequently used for resource inventories, management planning, and assessment analyses. Misclassification causes bias in these statistical areal estimates. For example, if a small percentage of a common cover type is misclassified as a rare...

Ultrahigh-rate supercapacitors with large capacitance based on edge oriented graphene coated carbonized cellulous paper as flexible freestanding electrodes

NASA Astrophysics Data System (ADS)

Ren, Guofeng; Li, Shiqi; Fan, Zhao-Xia; Hoque, Md Nadim Ferdous; Fan, Zhaoyang

2016-09-01

Large-capacitance and ultrahigh-rate electrochemical supercapacitors (UECs) with frequency response up to kilohertz (kHz) range are reported using light, thin, and flexible freestanding electrodes. The electrode is formed by perpendicularly edge oriented multilayer graphene/thin-graphite (EOG) sheets grown radially around individual fibers in carbonized cellulous paper (CCP), with cellulous carbonization and EOG deposition implemented in one step. The resulted ∼10 μm thick EOG/CCP electrode is light and flexible. The oriented porous structure of EOG with large surface area, in conjunction with high conductivity of the electrode, ensures ultrahigh-rate performance of the fabricated cells, with large areal capacitance of 0.59 mF cm-2 and 0.53 mF cm-2 and large phase angle of -83° and -80° at 120 Hz and 1 kHz, respectively. Particularly, the hierarchical EOG/CCP sheet structure allows multiple sheets stacked together for thick electrodes with almost linearly increased areal capacitance while maintaining the volumetric capacitance nearly no degradation, a critical merit for developing practical faraday-scale UECs. 3-layers of EOG/CCP electrode achieved an areal capacitance of 1.5 mF cm-2 and 1.4 mF cm-2 at 120 Hz and 1 kHz, respectively. This demonstration moves a step closer to the goal of bridging the frequency/capacitance gap between supercapacitors and electrolytic capacitors.

Heavy metal toxicity as a kill mechanism in impact caused mass extinctions

NASA Technical Reports Server (NTRS)

Wdowiak, T. J.; Davenport, S. A.; Jones, D. D.; Wdowiak, P.

1988-01-01

Heavy metals that are known to be toxic exist in carbonaceous chrondrites at abundances considerably in excess to that of the terrestrial crust. An impactor of relatively undifferentiated cosmic matter would inject into the terrestrial environment large quantities of toxic elements. The abundances of toxic metals found in the Allende CV carbonaceous chondrite and the ratio of meteoritic abundance to crustal abundance are: Cr, 3630 PPM, 30X; Co, 662 PPM, 23X; ni, 13300 PPm, 134X; se, 8.2 PPM, 164X; Os, 0.828 PPM, 166X. The resulting areal density for global dispersal of impactor derived heavy metals and their dilution with terrestrial ejecta are important factors in the determination of the significance of impactor heavy metal toxicity as a kill mechanism in impact caused mass extinctions. A 10 km-diameter asteroid having a density of 3 gram per cu cm would yield a global areal density of impact dispersed chondritic material of 3 kg per square meter. The present areal density of living matter on the terrestrial land surface is 1 kg per square meter. Dilution of impactor material with terrestrial ejecta is determined by energetics, with the mass of ejecta estimated to be in the range of 10 to 100 times that of the mass of the impactor. Because a pelagic impact would be the most likely case, the result would be a heavy metal rainout.

A Modeling Approach to Global Land Surface Monitoring with Low Resolution Satellite Imaging

NASA Technical Reports Server (NTRS)

Hlavka, Christine A.; Dungan, Jennifer; Livingston, Gerry P.; Gore, Warren J. (Technical Monitor)

1998-01-01

The effects of changing land use/land cover on global climate and ecosystems due to greenhouse gas emissions and changing energy and nutrient exchange rates are being addressed by federal programs such as NASA's Mission to Planet Earth (MTPE) and by international efforts such as the International Geosphere-Biosphere Program (IGBP). The quantification of these effects depends on accurate estimates of the global extent of critical land cover types such as fire scars in tropical savannas and ponds in Arctic tundra. To address the requirement for accurate areal estimates, methods for producing regional to global maps with satellite imagery are being developed. The only practical way to produce maps over large regions of the globe is with data of coarse spatial resolution, such as Advanced Very High Resolution Radiometer (AVHRR) weather satellite imagery at 1.1 km resolution or European Remote-Sensing Satellite (ERS) radar imagery at 100 m resolution. The accuracy of pixel counts as areal estimates is in doubt, especially for highly fragmented cover types such as fire scars and ponds. Efforts to improve areal estimates from coarse resolution maps have involved regression of apparent area from coarse data versus that from fine resolution in sample areas, but it has proven difficult to acquire sufficient fine scale data to develop the regression. A method for computing accurate estimates from coarse resolution maps using little or no fine data is therefore needed.

Spectral modeling of water ice-rich areas on Ceres' surface from Dawn-VIR data analysis: abundance and grain size retrieval

NASA Astrophysics Data System (ADS)

Raponi, Andrea; De Sanctis, Maria Cristina; Ciarniello, Mauro; Tosi, Federico; Combe, Jean-Philippe; Frigeri, Alessandro; Zambon, Francesca; Ammannito, Eleonora; Giacomo Carrozzo, Filippo; Magni, Gianfranco; Capria, Maria Teresa; Formisano, Michelangelo; Longobardo, Andrea; Palomba, Ernesto; Pieters, Carle; Russell, Christopher T.; Raymond, Carol; Dawn/VIR Team

2016-10-01

Dawn spacecraft orbits around Ceres since early 2015 acquiring a huge amount of data at different spatial resolutions during the several phases of the mission. VIR, the visible and InfraRed spectrometer onboard Dawn [1] allowed to detect the principal mineralogical phases present on Ceres: a large abundance of dark component, NH4-phillosilicates and carbonates.Water has been detected in small areas on Ceres' surface by the Dawn-VIR instrument. The most obvious finding is located in Oxo crater [2]. Further detections of water have been made during the Survey observation phase (1.1 km/pixel) and High-Altitude Mapping Orbit (400 m/px) [3]. During the LAMO phase (Low Altitude Mapping Orbit), the data with increased spatial resolution (100 m/px) coming from both regions have improved the detection of water, highlighting clear diagnostic water ice absorption features. In this study, we focused on spectral modeling of VIR spectra of Oxo and another crater (lon = 227°, lat 57°), near Messor crater.The Hapke radiative transfer model [4] has been applied in order to retrieve the water ice properties. We consider two types of mixtures: areal and intimate mixing. In areal mixing, the surface is modelled as patches of pure water ice, with each photon scattered within one patch. In intimate mixing, the particles of water ice are in contact with particles of the dark terrain, and both are involved in the scattering of a single photon. The best fit with the measured spectra has been derived with the areal mixture. The water ice abundance obtained is up to 15-20% within the field of view, and the grain size retrieved is of the order of 100-200 μm. Phyllosilicates and carbonates, which are ubiquitous on Ceres surface [5], have been also detected and modeled in correspondence with the icy regions. The water ice is typically located near and within the shadows projected by the crater rims. Further analysis is required to study the thermal state of the ice and its origin.References[1] De Sanctis M.C. et al., Space Sci. Rev., 2010[2] Combe J-Ph. et al., 2016, LPI N. 1903, 1820[3] Combe J.-Ph. Et al., 2016, DPS-EPSC[4] Hapke B., Cambridge Univ. Press., 1993, 2012[5] De Sanctis M.C. et al., 2015. Nature 242, 528

Surface geophysical investigation of the areal and vertical extent of metallic waste at the former Tyson Valley Powder Farm near Eureka, Missouri, Spring 2004

USGS Publications Warehouse

Ball, Lyndsay B.; Kress, Wade H.; Anderson, Eric D.; Teeple, Andrew; Ferguson, James W.; Colbert, Charles R.

2004-01-01

The former Tyson Valley Powder Farm near Eureka, Missouri, was used primarily as a storage facility for the production of small arms ammunition during 1941?47 and 1951?61. A secondary use of the site was for munitions testing and disposal. Surface exposures of small arms waste, characterized by brass shell casings and fragments, as well as other miscellaneous scrap metal are remnants of disposal practices that took place during U.S. Army operation and can be found throughout the site. Little historical information exists describing disposal practices, and more debris is believed to be buried in the subsurface. The U.S. Army Corps of Engineers has identified several areas of concern throughout the former Tyson Valley Powder Farm. A surface-geophysical investigation was performed by the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, to evaluate the areal and vertical extent of metallic debris in the subsurface within three of these areas of concern. Electromagnetic and magnetic methods were used to locate anomalies indicating relatively large concentrations of buried metallic debris within the selected areas of concern. Maps were created identifying twelve anomalous zones in the three areas of concern, and three of these zones were selected for further investigation. The extent and depth of the anomalies within these zones were explored using two-dimensional direct-current resistivity methods. Resistivity and time-domain induced polarization data were compared to the anomalous locations of the electromagnetic and magnetic surveys. The geophysical methods selected for this study were useful in determining the areal and vertical extent of metallic waste within the former Tyson Valley Powder Farm. However, electromagnetic and magnetic methods were not able to differentiate magnetic scrap metal from non-magnetic metallic small arms waste, most likely due to the small size and scattered distribution of the small arms waste, in addition to the mixing of both types of debris in the subsurface. Electromagnetic and magnetic data showed some zones of concentrated anomalies, while there was a general scattering of small anomalies throughout the site. Inverted resistivity sections, as well as induced polarization sections, showed the debris to have a maximum depth of approximately 1 to 2 meters below the surface.

Experiments on Bedrock Cover in a Highly Sinuous Channel

NASA Astrophysics Data System (ADS)

Parker, G.; Fernandez, R.; Stark, C. P.

2015-12-01

One of several mechanisms by which bedrock rivers can incise is abrasion of the bedrock surface by colliding sediment particles. This effect has been captured in terms of a "cover factor" corresponding to the areal fraction p of the bed that is covered with sediment. According to this formulation, a value of p equal to 1 corresponds to complete alluvial cover: sediment particles strike each other and no bedrock abrasion is accomplished. Correspondingly, a value of p equal to 0 corresponds to the absence of sediment: no particles are available to strike the bed, and again no bedrock abrasion is accomplished. Thus the condition 0 < p < 1 is hypothesized to be the condition for incision driven by abrasion. At the microscopic level, however, p can take only the binary values 0 and 1: either a point on the bedrock surface is covered or is not covered. Therefore, the value of p that enters into any morphodynamic formulation of cover must represent an average over some spatiotemporal window. Here we consider the case of a highly sinuous meandering flume. The bed is set in concrete to take the topography corresponding to purely alluvial mobile-bed equilibrium. The recirculation of sediment over this bed at below-capacity conditions leads to a complex pattern of free and forced bars that only partially cover the bed. At certain locations, such as near the inside of bends, the bed is always covered, where at other locations, such as right near the apexes of the very tight bends in the flume, the bed is almost never covered. At other locations, the instantaneous cover fluctuates between the binary values 0 and 1, reflecting the migration of bars of various sizes over the bedrock surface. The averaging of these binary values over appropriate time windows allows determination of the local spatial variation of p that can serve as input to a numerical model of the evolution of bedrock meandering channels.

Standard Procedure for Calibrating an Areal Calorimetry Based Dosimeter

DTIC Science & Technology

2015-05-01

detector target surface. In this case, the source was on for approximately 2.5 s, shortly after which the data acquisition ends. For this shot , the...no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control...48 APPENDIX D – CALIBRATION DATA SHOT RESULTS ...................................................... 49 APPENDIX E – SAMPLE

Application of index number theory to the construction of a water quality index: aggregated nutrient loadings related to the areal extent of hypoxia in the northern Gulf of Mexico

USDA-ARS?s Scientific Manuscript database

The development of an index for description and monitoring of surface water quality has received significant attention in the water resources literature in recent years, primarily because of the increasing need for assessing water quality and the complex, multidimensional data collected from water q...

Assessment of probabilistic areal reduction factors of precipitations for the entire French territory with gridded rainfall data.

NASA Astrophysics Data System (ADS)

Fouchier, Catherine; Maire, Alexis; Arnaud, Patrick; Cantet, Philippe; Odry, Jean

2016-04-01

The starting point of our study was the availability of maps of rainfall quantiles available for the entire French mainland territory at the spatial resolution of 1 km². These maps display the rainfall amounts estimated for different rainfall durations (from 15 minutes to 72 hours) and different return periods (from 2 years up to 1 000 years). They are provided by a regionalized stochastic hourly point rainfall generator, the SHYREG method which was previously developed by Irstea (Arnaud et al., 2007; Cantet and Arnaud, 2014). Being calibrated independently on numerous raingauges data (with an average density across the country of 1 raingauge per 200 km²), this method suffers from a limitation common to point-process rainfall generators: it can only reproduce point rainfall patterns and has no capacity to generate rainfall fields. It can't hence provide areal rainfall quantiles, the estimation of the latter being however needed for the construction of design rainfall or for the diagnostic of observed events. One means of bridging this gap between our local rainfall quantiles and areal rainfall quantiles is given by the concept of probabilistic areal reduction factors of rainfall (ARF) as defined by Omolayo (1993). This concept enables to estimate areal rainfall of a particular frequency within a certain amount of time from point rainfalls of the same frequency and duration. Assessing such ARF for the whole French territory is of particular interest since it should allow us to compute areal rainfall quantiles, and eventually watershed rainfall quantiles, by using the already available grids of statistical point rainfall of the SHYREG method. Our purpose was then to assess these ARF thanks to long time-series of spatial rainfall data. We have used two sets of rainfall fields: i) hourly rainfall fields from a 10-year reference database of Quantitative Precipitation Estimation (QPE) over France (Tabary et al., 2012), ii) daily rainfall fields resulting from a 53-year high-resolution atmospheric reanalysis over France with the SAFRAN-gauge-based analysis system (Vidal et al., 2010). We have then built samples of maximal rainfalls for each cell location (the "point" rainfalls) and for different areas centered on each cell location (the areal rainfalls) of these gridded data. To compute rainfall quantiles, we have fitted a Gumbel law, with the L-moment method, on each of these samples. Our daily and hourly ARF have then shown four main trends: i) a sensitivity to the return period, with ARF values decreasing when the return period increases; ii) a sensitivity to the rainfall duration, with ARF values decreasing when the rainfall duration decreases; iii) a sensitivity to the season, with ARF values smaller for the summer period than for the winter period; iv) a sensitivity to the geographical location, with low ARF values in the French Mediterranean area and ARF values close to 1 for the climatic zones of Northern and Western France (oceanic to semi-continental climate). The results of this data-intensive study led for the first time on the whole French territory are in agreement with studies led abroad (e.g. Allen and DeGaetano 2005, Overeem et al. 2010) and confirm and widen the results of previous studies that were carried out in France on smaller areas and with fewer rainfall durations (e.g. Ramos et al., 2006, Neppel et al., 2003). References Allen R. J. and DeGaetano A. T. (2005). Areal reduction factors for two eastern United States regions with high rain-gauge density. Journal of Hydrologic Engineering 10(4): 327-335. Arnaud P., Fine J.-A. and Lavabre J. (2007). An hourly rainfall generation model applicable to all types of climate. Atmospheric Research 85(2): 230-242. Cantet, P. and Arnaud, P. (2014). Extreme rainfall analysis by a stochastic model: impact of the copula choice on the sub-daily rainfall generation, Stochastic Environmental Research and Risk Assessment, Springer Berlin Heidelberg, 28(6), 1479-1492. Neppel L., Bouvier C. and Lavabre J. (2003). Areal reduction factor probabilities for rainfall in Languedoc Roussillon. IAHS-AISH Publication (278): 276-283. Omolayo, A. S. (1993). On the transposition of areal reduction factors for rainfall frequency estimation. Journal of Hydrology 145 (1-2): 191-205. Overeem A., Buishand T. A., Holleman I. and Uijlenhoet R. (2010). Extreme value modeling of areal rainfall from weather radar. Water Resources Research 46(9): 10 p. Ramos M.-H., Leblois E., Creutin J.-D. (2006). From point to areal rainfall: Linking the different approaches for the frequency characterisation of rainfalls in urban areas. Water Science and Technology. 54(6-7): 33-40. Tabary P., Dupuy P., L'Henaff G., Gueguen C., Moulin L., Laurantin O., Merlier C., Soubeyroux J. M. (2012). A 10-year (1997-2006) reanalysis of Quantitative Precipitation Estimation over France: methodology and first results. IAHS-AISH Publication (351) : 255-260. Vidal J.-P., Martin E., Franchistéguy L., Baillon M. and Soubeyroux J.-M. (2010). A 50-year high-resolution atmospheric reanalysis over France with the Safran system. International Journal of Climatology 30(11): 1627-1644.

Azimuthal filter to attenuate ground roll noise in the F-kx-ky domain for land 3D-3C seismic data with uneven acquisition geometry

NASA Astrophysics Data System (ADS)

Arevalo-Lopez, H. S.; Levin, S. A.

2016-12-01

The vertical component of seismic wave reflections is contaminated by surface noise such as ground roll and secondary scattering from near surface inhomogeneities. A common method for attenuating these, unfortunately often aliased, arrivals is via velocity filtering and/or multichannel stacking. 3D-3C acquisition technology provides two additional sources of information about the surface wave noise that we exploit here: (1) areal receiver coverage, and (2) a pair of horizontal components recorded at the same location as the vertical component. Areal coverage allows us to segregate arrivals at each individual receiver or group of receivers by direction. The horizontal components, having much less compressional reflection body wave energy than the vertical component, provide a template of where to focus our energies on attenuating the surface wave arrivals. (In the simplest setting, the vertical component is a scaled 90 degree phase rotated version of the radial horizontal arrival, a potential third possible lever we have not yet tried to integrate.) The key to our approach is to use the magnitude of the horizontal components to outline a data-adaptive "velocity" filter region in the w-Kx-Ky domain. The big advantage for us is that even in the presence of uneven receiver geometries, the filter automatically tracks through aliasing without manual sculpting and a priori velocity and dispersion estimation. The method was applied to an aliased synthetic dataset based on a five layer earth model which also included shallow scatterers to simulate near-surface inhomogeneities and successfully removed both the ground roll and scatterers from the vertical component (Figure 1).

An Areal-Typological Study of American Indian Languages North of Mexico.

ERIC Educational Resources Information Center

Sherzer, Joel

This study attempts to provide a systematic mapping of the linguistic structural properties of North American Indian languages. The study includes: (1) the history of areal-typological linguistic studies in North America; (2) a framework for the presentation of areal linguistic phenomena in North America; (3) a presentation and discussion of the…

Highly flexible, freestanding tandem sulfur cathodes for foldable Li–S batteries with a high areal capacity

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

Chang, Chi-Hao; Chung, Sheng-Heng; Manthiram, Arumugam

Li–S batteries with a high theoretical capacity are considered as the most promising candidate to satisfy the increasing demand for batteries with a high areal capacity. However, the low sulfur loading (<2 mg cm -2) and poor flexibility of current Li–S batteries limit their application in establishing foldable Li–S batteries with a high areal capacity. Here, to solve this problem, we employ here a free-standing flexible tandem sulfur cathode with a remarkably high sulfur loading to demonstrate foldable, high-areal-capacity Li–S batteries. The design of the tandem cathode readily increases the sulfur loading and effectively retards the migration of polysulfides. Therefore,more » the Li–S cell employing the tandem cathode exhibits a high initial areal capacity of 12.3 mA h cm -2 with stable cycling stability even with a high sulfur loading of up to 16 mg cm -2. These tandem cathodes are promising for foldable Li–S cells with a high areal capacity and energy density.« less

Highly flexible, freestanding tandem sulfur cathodes for foldable Li–S batteries with a high areal capacity

DOE PAGES

Chang, Chi-Hao; Chung, Sheng-Heng; Manthiram, Arumugam

2017-01-05

Li–S batteries with a high theoretical capacity are considered as the most promising candidate to satisfy the increasing demand for batteries with a high areal capacity. However, the low sulfur loading (<2 mg cm -2) and poor flexibility of current Li–S batteries limit their application in establishing foldable Li–S batteries with a high areal capacity. Here, to solve this problem, we employ here a free-standing flexible tandem sulfur cathode with a remarkably high sulfur loading to demonstrate foldable, high-areal-capacity Li–S batteries. The design of the tandem cathode readily increases the sulfur loading and effectively retards the migration of polysulfides. Therefore,more » the Li–S cell employing the tandem cathode exhibits a high initial areal capacity of 12.3 mA h cm -2 with stable cycling stability even with a high sulfur loading of up to 16 mg cm -2. These tandem cathodes are promising for foldable Li–S cells with a high areal capacity and energy density.« less

The Northeast Monsoon's Impact on Mixing, Phytoplankton Biomass and Nutrient Cycling in the Arabian Sea

NASA Technical Reports Server (NTRS)

Wiggert, J. D.; Jones, B. H.; Dickey, T. D.; Brink, K. H.; Weller, R. A.; Marra, J.; Codispoti, L. A.

2000-01-01

In the northern Arabian Sea, atmospheric conditions during the Northeast (winter) Monsoon lead to deep convective mixing. Due to the proximity of the permanent pyncnocline to the sea surface, this mixing does not penetrate below 125 m. However, a strong nitracline is also present and the deep convection results in significant nitrate flux into the surface waters. This leads to nitrate concentrations over the upper 100 m that exceed 4 micrometers toward the end of the Monsoon. During the 1994/1995 US JGOFS/Arabian Sea expedition, the mean areal gross primary production over two successive Northeast Monsoons was determined to be 1.35gC/sq m/d. Thus, despite the deep penetrative convection, high rates of primary productivity were maintained. An interdisciplinary model was developed to elucidate the biogeochemical processes involved in supporting the elevated productivity. This model consists of a 1-D mixed-layer model coupled to a set of equations that tracked phytoplankton growth and the concentration of the two major nutrients (nitrate and ammonium). Zooplankton grazing was parameterized by rate constant determined by shipboard experiments. Model boundary conditions consist of meteorological time-series measured from the surface buoy that was part of the ONR Arabian Sea Experiment's central mooring. Our numerical experiments show that elevated surface evaporation, and the associated salinization of the mixed layer, strongly contributes to the frequency and penetration depth of the observed convective mixing. Cooler surface temperatures, increased nitrate entrainment, reduced water column stratification, and lower near-surface chlorophyll a concentrations all result from this enhanced mixing. The model also captured a dependence on regenerated nitrogen observed in nutrient uptake experiments performed during the Northeast Monsoon. Our numerical experiments also indicate that variability in mean pycnocline depth causes up to a 25% reduction in areal chlorophyll a concentration. We hypothesize that such shifts in pycnocline depth may contribute to the interannual variations in primary production and surface chlorophyll a concentration that have been previously observed in this region.

76 FR 70331 - List of Approved Spent Fuel Storage Casks: MAGNASTOR ® System, Revision 2

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-14

... various boron-10 areal densities for use with Pressurized Water Reactor and Boiling Water Reactor baskets... add various boron-10 areal densities for use with Pressurized Water Reactor and Boiling Water Reactor....1.1 to add various boron-10 areal densities for use with Pressurized Water Reactor and Boiling Water...

Improving global paleogeography since the late Paleozoic using paleobiology

NASA Astrophysics Data System (ADS)

Cao, Wenchao; Zahirovic, Sabin; Flament, Nicolas; Williams, Simon; Golonka, Jan; Dietmar Müller, R.

2017-12-01

Paleogeographic reconstructions are important to understand Earth's tectonic evolution, past eustatic and regional sea level change, paleoclimate and ocean circulation, deep Earth resources and to constrain and interpret the dynamic topography predicted by mantle convection models. Global paleogeographic maps have been compiled and published, but they are generally presented as static maps with varying map projections, different time intervals represented by the maps and different plate motion models that underlie the paleogeographic reconstructions. This makes it difficult to convert the maps into a digital form and link them to alternative digital plate tectonic reconstructions. To address this limitation, we develop a workflow to restore global paleogeographic maps to their present-day coordinates and enable them to be linked to a different tectonic reconstruction. We use marine fossil collections from the Paleobiology Database to identify inconsistencies between their indicative paleoenvironments and published paleogeographic maps, and revise the locations of inferred paleo-coastlines that represent the estimated maximum transgression surfaces by resolving these inconsistencies. As a result, the consistency ratio between the paleogeography and the paleoenvironments indicated by the marine fossil collections is increased from an average of 75 % to nearly full consistency (100 %). The paleogeography in the main regions of North America, South America, Europe and Africa is significantly revised, especially in the Late Carboniferous, Middle Permian, Triassic, Jurassic, Late Cretaceous and most of the Cenozoic. The global flooded continental areas since the Early Devonian calculated from the revised paleogeography in this study are generally consistent with results derived from other paleoenvironment and paleo-lithofacies data and with the strontium isotope record in marine carbonates. We also estimate the terrestrial areal change over time associated with transferring reconstruction, filling gaps and modifying the paleogeographic geometries based on the paleobiology test. This indicates that the variation of the underlying plate reconstruction is the main factor that contributes to the terrestrial areal change, and the effect of revising paleogeographic geometries based on paleobiology is secondary.

Numerical simulation of ground-water flow in the central part of the western San Joaquin Valley, California

USGS Publications Warehouse

Belitz, Kenneth; Phillips, Steven P.; Gronberg, Jo Ann M.

1993-01-01

The occurrence of selenium in agricultural drain water in the central part of the western San Joaquin Valley, California, has focused concern on strategies for managing shallow, saline ground water. To assess alternatives to agricultural drains, a three-dimensional, finite-difference numerical model of the regional groundwater flow system was developed. This report documents the mathematical approach used to model the flow system, the data base on which the model is based, and the methods used to calibrate the model. The 550-square-mile study area includes parts of the Panoche Creek alluvial fan and parts of the Little Panoche Creek and Cantua Creek alluvial fans. The model simulates transient flow in the semiconfined and confined zones above and below the Corcoran Clay Member of the Tulare Formation of Pleistocene age. The model incorporates areally distributed ground-water recharge, areally and vertically distributed pumping, regional-collector drains in the Wesdands Water District (operative from 1980 to 1985), on-farm drains in parts of the Panoche, Broadview, and Firebaugh Water Districts, and bare-soil evaporation (which occurs if the water table is within 7 feet of land surface). The model also incorporates texture-based estimates of hydraulic conductivity, where texture is defined as the fraction of coarse-grained deposits present in a given subsurface interval. The numerical model was developed using hydrologic data from 1972 to 1988. Most of the parameters incorporated into the model were evaluated independently of the model, including system geometry, the distribution of texture, the altitudes of the water table and potentiometric surface of the confined zone in 1972 (initial condition), the hydraulic conductivity of coarse-grained deposits derived from the Coast Ranges, the hydraulic conductivity of coarse-grained deposits derived from the Sierra Nevada, specific storage, recharge, pumping, and parameters needed to incorporate drains and bare-soil evaporation. Four parameters were calibration variables: the hydraulic conductivity of fine-grained deposits in the semiconfined zone, the hydraulic conductivity of the Corcoran Clay Member, specific yield, and the transmissivity of the confined zone. The model was calibrated in two phases. In the first phase, a steady-state model of the ground-water flow system in 1984 was used to constrain the relation between the hydraulic conductivity of fine-grained deposits in the semiconfined zone and the hydraulic conductivity of the Corcoran Clay Member, thus reducing the number of independent variables from four to three. In the second phase of calibration, the change in altitude of the water table from 1972 to 1984, the change in altitude of the potentiometric surface of the confined zone from 1972 to 1984, and the number of model cells subject to bare-soil evaporation from 1972 to 1988 were used to evaluate the remaining three variables. The calibrated model reproduces the average change in water-table altitude (1972-84) to within 0.4 foot (average measured change 11.5 feet) and the average change in confined zone head (1972- 84) to within 19 feet (average measured change 120 feet). The simulated time-series record of the total number of model cells subject to bare-soil evaporation (each cell is 1 mile square) is within the range of the measured data. The measured values are at a minimum in October and a maximum in July. The October values ranged from 103 in 1972 to 132 in 1984 (the drains were closed in 1985) to 151 in 1988. The July values ranged from 144 in 1973 to 198 in 1984, to 204 in 1988. The simulated values ranged from 103 in 1972 to 161 in 1984, to 208 in 1988.

Dependence of Long Bone Flexural Properties on Bone Mineral Distribution

NASA Technical Reports Server (NTRS)

Katz, BethAnn; Cleek, Tammy M.; Whalen, Robert T.; Connolly, James P. (Technical Monitor)

1995-01-01

The objective of this study is to assess whether a non-invasive determination of long bone cross-sectional areal properties using bone densitometry accurately estimates true long bone flexural properties. In this study, section properties of two pairs of human female embalmed tibiae were compared using two methods: special analysis of bone densitometry data, and experimental determination of flexural regidities from bone surface strain measurements during controlled loading.

Combination of surface- and interference-enhanced Raman scattering by CuS nanocrystals on nanopatterned Au structures

PubMed Central

Yeryukov, Nikolay A; Sveshnikova, Larisa L; Duda, Tatyana A; Rodyakina, Ekaterina E; Gridchin, Victor A; Sheremet, Evgeniya S; Zahn, Dietrich R T

2015-01-01

Summary We present the results of a Raman study of optical phonons in CuS nanocrystals (NCs) with a low areal density fabricated through the Langmuir–Blodgett technology on nanopatterned Au nanocluster arrays using a combination of surface- and interference-enhanced Raman scattering (SERS and IERS, respectively). Micro-Raman spectra of one monolayer of CuS NCs deposited on a bare Si substrate reveal only features corresponding to crystalline Si. However, a new relatively strong peak occurs in the Raman spectrum of CuS NCs on Au nanocluster arrays at 474 cm−1. This feature is related to the optical phonon mode in CuS NCs and manifests the SERS effect. For CuS NCs deposited on a SiO2 layer this phonon mode is also observed due to the IERS effect. Its intensity changes periodically with increasing SiO2 layer thickness for different laser excitation lines and is enhanced by a factor of about 30. CuS NCs formed on Au nanocluster arrays fabricated on IERS substrates combine the advantages of SERS and IERS and demonstrate stronger SERS enhancement allowing for the observation of Raman signals from CuS NCs with an ultra-low areal density. PMID:25977845

Holey nickel-cobalt layered double hydroxide thin sheets with ultrahigh areal capacitance

NASA Astrophysics Data System (ADS)

Zhi, Lei; Zhang, Wenliang; Dang, Liqin; Sun, Jie; Shi, Feng; Xu, Hua; Liu, Zonghuai; Lei, Zhibin

2018-05-01

Strong coupling of electroactive components on conductive carbonaceous matrix to fabricate flexible hybrid electrodes represents a promising approach towards high performance supercapacitors. This work reports the fabrication of holey nickel cobalt layered double hydroxide (NiCo-LDH) nanosheets that are vertically grown on the cotton cloth-derived activated textile carbon (aTC). The abundant nanoholes on the thin-sheet NiCo-LDH not only enhance the electrode efficiency for efficient Faradaic redox reactions but also facilitate access of electrolyte to the electrode surface, thus giving rise to 70% capacitance arising from their outer surface. As a result, the aTC-NiCo hybrid electrode is capable of simultaneously achieving extremely high areal capacitance (6.37 F cm-2), mass capacitance (525 F g-1) and volumetric capacitance (249 F cm-3) at a practical level of mass loading (6.72 mg cm-2). Moreover, a solid-state asymmetric capacitor built with aTC-NiCo as positive electrode and active carbon-coated on aTC as negative electrode can deliver a volumetric energy density of 7.4 mWh cm-3 at a power density of 103 mW cm-3, while preserving a superior power performance, satisfying cycling stability and good mechanical flexibility.

The Uranian satellites and Hyperion - New spectrophotometry and compositional implications

NASA Astrophysics Data System (ADS)

Brown, R. H.

1983-12-01

New reflectance spectra at 3.5 percent resolution have been obtained for Ariel, Titania, Oberon, and Hyperion in the 0.8 to 1.6-micron spectrum region. The new spectra show no absorptions other than the 1.5 micron water-ice feature (within the precision of the data), and demonstrate extension into the 0.8- to 1.6 micron region of the 1.5- to 2.5 micron spectral similarity ofo Ariel to Hyperion (Brown and Cruikshank, 1983). The new data confirm the presence of a dark, spectrally bland component on/in the water-ice surfaces of the Uranian satellites, which, with some reservations, has spectral similarities to the dark substance on the leading side of lapetus and the dark material on/in the surface of Hyperion, as well as other dark, spectrally neutral substances such as charcoal. Attempts were made to match the spectra of Ariel, Titania, and Oberon with additive reflectance mixes (aeral coverage) of fine-grained water frost and various dark components such as charcoal, lampblack, and charcoal-water-ice mixtures. The results were broad limits on the amounts of possible areal coverage of a charcoal-like spectral component on the surfaces of the Uranian satellites, but the data are not of sufficient precision to conclusively determine whether the dominant mode of contaminant dispersal is areal or voluminal. The effect of highly variegated albedos on the diameters derived by Brown, Cruikshank, and Morrison (1982) is found to be small.

The Uranian satellites and Hyperion - New spectrophotometry and compositional implications

NASA Technical Reports Server (NTRS)

Brown, R. H.

1983-01-01

New reflectance spectra at 3.5 percent resolution have been obtained for Ariel, Titania, Oberon, and Hyperion in the 0.8 to 1.6-micron spectrum region. The new spectra show no absorptions other than the 1.5 micron water-ice feature (within the precision of the data), and demonstrate extension into the 0.8- to 1.6 micron region of the 1.5- to 2.5 micron spectral similarity ofo Ariel to Hyperion (Brown and Cruikshank, 1983). The new data confirm the presence of a dark, spectrally bland component on/in the water-ice surfaces of the Uranian satellites, which, with some reservations, has spectral similarities to the dark substance on the leading side of lapetus and the dark material on/in the surface of Hyperion, as well as other dark, spectrally neutral substances such as charcoal. Attempts were made to match the spectra of Ariel, Titania, and Oberon with additive reflectance mixes (aeral coverage) of fine-grained water frost and various dark components such as charcoal, lampblack, and charcoal-water-ice mixtures. The results were broad limits on the amounts of possible areal coverage of a charcoal-like spectral component on the surfaces of the Uranian satellites, but the data are not of sufficient precision to conclusively determine whether the dominant mode of contaminant dispersal is areal or voluminal. The effect of highly variegated albedos on the diameters derived by Brown, Cruikshank, and Morrison (1982) is found to be small.

Ultrahigh-Capacity Lithium-Oxygen Batteries Enabled by Dry-Pressed Holey Graphene Air Cathodes.

PubMed

Lin, Yi; Moitoso, Brandon; Martinez-Martinez, Chalynette; Walsh, Evan D; Lacey, Steven D; Kim, Jae-Woo; Dai, Liming; Hu, Liangbing; Connell, John W

2017-05-10

Lithium-oxygen (Li-O 2 ) batteries have the highest theoretical energy density of all the Li-based energy storage systems, but many challenges prevent them from practical use. A major obstacle is the sluggish performance of the air cathode, where both oxygen reduction (discharge) and oxygen evolution (charge) reactions occur. Recently, there have been significant advances in the development of graphene-based air cathode materials with a large surface area and catalytically active for both oxygen reduction and evolution reactions, especially with additional catalysts or dopants. However, most studies reported so far have examined air cathodes with a limited areal mass loading rarely exceeding 1 mg/cm 2 . Despite the high gravimetric capacity values achieved, the actual (areal) capacities of those batteries were far from sufficient for practical applications. Here, we present the fabrication, performance, and mechanistic investigations of high-mass-loading (up to 10 mg/cm 2 ) graphene-based air electrodes for high-performance Li-O 2 batteries. Such air electrodes could be easily prepared within minutes under solvent-free and binder-free conditions by compression-molding holey graphene materials because of their unique dry compressibility associated with in-plane holes on the graphene sheet. Li-O 2 batteries with high air cathode mass loadings thus prepared exhibited excellent gravimetric capacity as well as ultrahigh areal capacity (as high as ∼40 mAh/cm 2 ). The batteries were also cycled at a high curtailing areal capacity (2 mAh/cm 2 ) and showed a better cycling stability for ultrathick cathodes than their thinner counterparts. Detailed post-mortem analyses of the electrodes clearly revealed the battery failure mechanisms under both primary and secondary modes, arising from the oxygen diffusion blockage and the catalytic site deactivation, respectively. These results strongly suggest that the dry-pressed holey graphene electrodes are a highly viable architectural platform for high-capacity, high-performance air cathodes in Li-O 2 batteries of practical significance.

Surface-water investigations at Barrow, Alaska

USGS Publications Warehouse

Jones, Stanley H.

1972-01-01

The U.S. Public Health Service is currently developing plans for a long-term water supply and sewage treatment system for the village of Barrow, Alaska. To assist in planning, the U.S. Geological Survey was requested to initiate a cooperative streamflow data-collection program with the U.S. Public Health Service in June 1972 to determine the availability of surface water and the areal distribution of runoff in the Barrow area. This basic-data report summarizes the streamflow data collected from June 1 through July 10, 1972, at three gaging stations in the Barrow area (fig. 1) and discusses the future data-collection program.

Water and processes of degradation in the Martian landscape

NASA Technical Reports Server (NTRS)

Milton, D. J.

1973-01-01

It is shown that erosion has been active on Mars so that many of the surface landforms are products of degradation. Unlike earth, erosion has not been a universal process, but one areally restricted and intermittently active so that a landscape is the product of one or two cycles of erosion and large areas of essentially undisturbed primitive terrain; running water has been the principal agent of degradation. Many features on Mars are most easily explained by assuming running surface water at some time in the past; for a few features, running water is the only possible explanation.

Cracks and blisters formed close to a silicon wafer surface by He-H co-implantation at low energy

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

Cherkashin, N., E-mail: nikolay.cherkashin@cemes.fr; Darras, F.-X.; Claverie, A.

2015-12-28

We have studied the effect of reducing the implantation energy towards low keV values on the areal density of He and H atoms stored within populations of blister cavities formed by co-implantation of the same fluence of He then H ions into Si(001) wafers and annealing. Using a variety of experimental techniques, we have measured blister heights and depth from the surface, diameter, areal density of the cracks from which they originate as functions of implantation energy and fluence. We show that there is a direct correlation between the diameters of the cracks and the heights of the associated blisters.more » This correlation only depends on the implantation energy, i.e., only on the depth at which the cracks are located. Using finite element method modeling, we infer the pressure inside the blister cavities from the elastic deformations they generate, i.e., from the height of the blisters. From this, we demonstrate that the gas pressure within a blister only depends on the diameter of the associated crack and not on its depth position and derive an analytical expression relating these parameters. Relating the pressure inside a blister to the respective concentrations of gas molecules it contains, we deduce the areal densities of He and H atoms contained within the populations of blisters. After low-energy implantations (8 keV He{sup +}, 3 keV H{sup +}), all the implanted He and H atoms contribute to the formation of the blisters. There is no measurable exo-diffusion of any of the implanted gases, in contrast to what was assumed at the state of the art to explain the failure of the Smart-Cut technology when using very low energy ion implantation for the fabrication of ultra-thin layers. Alternative explanations must be investigated.« less

The relative contributions of forest growth and areal expansion to forest biomass carbon

Treesearch

P. Li; J. Zhu; H. Hu; Z. Guo; Y. Pan; R. Birdsey; J. Fang

2016-01-01

Forests play a leading role in regional and global terrestrial carbon (C) cycles. Changes in C sequestration within forests can be attributed to areal expansion (increase in forest area) and forest growth (increase in biomass density). Detailed assessment of the relative contributions of areal expansion and forest growth to C sinks is crucial to reveal the mechanisms...

Spinstand demonstration of areal density enhancement using two-dimensional magnetic recording (invited)

NASA Astrophysics Data System (ADS)

Lippman, Thomas; Brockie, Richard; Coker, Jon; Contreras, John; Galbraith, Rick; Garzon, Samir; Hanson, Weldon; Leong, Tom; Marley, Arley; Wood, Roger; Zakai, Rehan; Zolla, Howard; Duquette, Paul; Petrizzi, Joe

2015-05-01

Exponential growth of the areal density has driven the magnetic recording industry for almost sixty years. But now areal density growth is slowing down, suggesting that current technologies are reaching their fundamental limit. The next generation of recording technologies, namely, energy-assisted writing and bit-patterned media, remains just over the horizon. Two-Dimensional Magnetic Recording (TDMR) is a promising new approach, enabling continued areal density growth with only modest changes to the heads and recording electronics. We demonstrate a first generation implementation of TDMR by using a dual-element read sensor to improve the recovery of data encoded by a conventional low-density parity-check (LDPC) channel. The signals are combined with a 2D equalizer into a single modified waveform that is decoded by a standard LDPC channel. Our detection hardware can perform simultaneous measurement of the pre- and post-combined error rate information, allowing one set of measurements to assess the absolute areal density capability of the TDMR system as well as the gain over a conventional shingled magnetic recording system with identical components. We discuss areal density measurements using this hardware and demonstrate gains exceeding five percent based on experimental dual reader components.

Material engineering to fabricate rare earth erbium thin films for exploring nuclear energy sources

NASA Astrophysics Data System (ADS)

Banerjee, A.; Abhilash, S. R.; Umapathy, G. R.; Kabiraj, D.; Ojha, S.; Mandal, S.

2018-04-01

High vacuum evaporation and cold-rolling techniques to fabricate thin films of the rare earth lanthanide-erbium have been discussed in this communication. Cold rolling has been used for the first time to successfully fabricate films of enriched and highly expensive erbium metal with areal density in the range of 0.5-1.0 mg/cm2. The fabricated films were used as target materials in an advanced nuclear physics experiment. The experiment was designed to investigate isomeric states in the heavy nuclei mass region for exploring physics related to nuclear energy sources. The films fabricated using different techniques varied in thickness as well as purity. Methods to fabricate films with thickness of the order of 0.9 mg/cm2 were different than those of 0.4 mg/cm2 areal density. All the thin films were characterized using multiple advanced techniques to accurately ascertain levels of contamination as well as to determine their exact surface density. Detailed fabrication methods as well as characterization techniques have been discussed.

Phobos/Deimos sample return via solar sail.

PubMed

Matloff, Gregory L; Taylor, Travis; Powell, Conley; Moton, Tryshanda

2005-12-01

A sample-return mission to the Martian satellites using a con-temporary solar sail for all post-Earth-escape propulsion is proposed. The 0.015 kg/m(2) areal mass-thickness sail unfurls after launch and injection onto a Mars-bound Hohmann-transfer ellipse. Structure and payload increase spacecraft areal mass thickness to 0.028 kg/m(2). During the Mars encounter, the sail functions as a parachute in the outer atmosphere of Mars to accomplish aerocapture. On-board thrusters or the sail maneuver the spacecraft into an orbit with periapsis near Mars and apoapsis near Phobos. The orbit is circularized for Phobos-rendezvous; surface samples are collected. The sail then raises the orbit for Deimos-rendezvous and sample collection. The sail next places the spacecraft on an Earth-bound Hohmann-transfer ellipse. During Earth encounter, the sail accomplishes Earth-aerocapture or partially decelerates the sample container for entry into the Earth's atmosphere. Mission mass budget is about 218 grams and mission duration is less than five years.

Direct observation of feedout-related areal mass oscillations in planar plastic targets.

NASA Astrophysics Data System (ADS)

Aglitskiy, Y.; Metzler, N.; Velikovich, A. L.; Karasik, M.; Serlin, V.; Pawley, C.; Mostovych, A. N.; Schmitt, A. J.; Obenschain, S. P.; Gardner, J. H.

2001-10-01

"Feedout" means the transfer of mass perturbations from the rear to the front surface of a driven target. The oscillations are expected if the perturbation wavelength λ is not large compared to 2π L_s, where Ls is the shock-compressed target thickness. We report the first direct experimental observation of areal mass oscillation associated with feedout, followed by the onset of exponential RT growth. Our experiments were performed with the Nike KrF laser at irradiation 50 TW/cm^2. The mass redistribution in the target was observed with the aid of monochromatic x-ray imaging coupled to a streak camera. We used 40 to 60 μm thick CH targets rippled on the rear side with wavelengths of either 30 or 45 μm, the ratio 2π L_s/λ thus being close to 2. Two phase reversals of mass variation predicted by the theory and simulations were consistently observed both on the original images and on the time histories of Fourier amplitudes.

Phobos/Deimos Sample Return via Solar Sail

NASA Technical Reports Server (NTRS)

Matloff, Gregory L.; Taylor, Travis; Powell, Conley; Moton, Tryshanda

2004-01-01

Abstract A sample-return mission to the martian satellites using a contemporary solar sail for all post-Earth-escape propulsion is proposed. The 0.015 kg/sq m areal mass-thickness sail unfurls after launch and injection onto a Mars-bound Hohmann-transfer ellipse. Structure and pay!oad increase spacecraft areal mass thickness to 0.028 kg/sq m. During Mars-encounter, the sail functions parachute-like in Mars s outer atmosphere to accomplish aerocapture. On-board thrusters or the sail maneuver the spacecraft into an orbit with periapsis near Mars and apoapsis near Phobos. The orbit is circularized for Phobos-rendezvous; surface samples are collected. The sail then raises the orbit for Deimos-rendezvous and sample collection. The sail next places the spacecraft on an Earth-bound Hohmann-transfer ellipse. During Earth-encounter, the sail accomplishes Earth-aerocapture or partially decelerates the sample container for entry into Earth s atmosphere. Mission mass budget is about 218 grams and; mission duration is <5 years.

Group-III Nitride Field Emitters

NASA Technical Reports Server (NTRS)

Bensaoula, Abdelhak; Berishev, Igor

2008-01-01

Field-emission devices (cold cathodes) having low electron affinities can be fabricated through lattice-mismatched epitaxial growth of nitrides of elements from group III of the periodic table. Field emission of electrons from solid surfaces is typically utilized in vacuum microelectronic devices, including some display devices. The present field-emission devices and the method of fabricating them were developed to satisfy needs to reduce the cost of fabricating field emitters, make them compatible with established techniques for deposition of and on silicon, and enable monolithic integration of field emitters with silicon-based driving circuitry. In fabricating a device of this type, one deposits a nitride of one or more group-III elements on a substrate of (111) silicon or other suitable material. One example of a suitable deposition process is chemical vapor deposition in a reactor that contains plasma generated by use of electron cyclotron resonance. Under properly chosen growth conditions, the large mismatch between the crystal lattices of the substrate and the nitride causes strains to accumulate in the growing nitride film, such that the associated stresses cause the film to crack. The cracks lie in planes parallel to the direction of growth, so that the growing nitride film becomes divided into microscopic growing single-crystal columns. The outer ends of the fully-grown columns can serve as field-emission tips. By virtue of their chemical compositions and crystalline structures, the columns have low work functions and high electrical conductivities, both of which are desirable for field emission of electrons. From examination of transmission electron micrographs of a prototype device, the average column width was determined to be about 100 nm and the sharpness of the tips was determined to be characterized by a dimension somewhat less than 100 nm. The areal density of the columns was found to about 5 x 10(exp 9)/sq cm . about 4 to 5 orders of magnitude greater than the areal density of tips in prior field-emission devices. The electric field necessary to turn on the emission current and the current per tip in this device are both lower than in prior field-emission devices, such that it becomes possible to achieve longer operational lifetime. Moreover, notwithstanding the lower current per tip, because of the greater areal density of tips, it becomes possible to achieve greater current density averaged over the cathode area. The thickness of the grown nitride film (equivalently, the length of the columns) could lie between about 0.5 microns and a few microns; in any event, a thickness of about 1 micron is sufficient and costs less than do greater thicknesses. It may be possible to grow nitride emitter columns on glass or other substrate materials that cost less than silicon does. What is important in the choice of substrate material is the difference between the substrate and nitride crystalline structures. Inasmuch as the deposition process is nondestructive, an ability to grow emitter columns on a variety of materials would be advantageous in that it would facilitate the integration of field-emitter structures onto previously processed integrated circuits.

Feedback dynamics of grazing lawns: Coupling vegetation change with animal growth

USGS Publications Warehouse

Person, Brian T.; Herzog, M.P.; Ruess, Roger W.; Sedinger, J.S.; Anthony, R. Michael; Babcock, C.A.

2003-01-01

We studied the effects of grazing by Black Brant (Branta bernicla nigricans) geese (hereafter Brant) on plant community zonation and gosling growth between 1987 and 2000 at a nesting colony in southwestern Alaska. The preferred forage of Brant, Carex subspathacea, is only found as a grazing lawn. An alternate forage species, C. ramenskii, exists primarily as meadow but also forms grazing lawns when heavily grazed. We mowed plots of ungrazed C. ramenskii meadows to create swards that Brant could select and maintain as grazing lawns. Fecal counts were higher on mowed plots than on control plots in the year after plots were mowed. Both nutritional quality and aboveground biomass of C. ramenskii in mowed plots were similar to that of C. subspathacea grazing lawns. The areal extent of grazing lawns depends in part on the population size of Brant. High Brant populations can increase the areal extent of grazing lawns, which favors the growth of goslings. Grazing lawns increased from 3% to 8% of surface area as the areal extent of C. ramenskii meadows declined between 1991 and 1999. Gosling mass was lower early in this time period due to density dependent effects. As the goose population stabilized, and area of grazing lawns increased, gosling mass increased between 1993 and 1999. Because larger goslings have increased survival, higher probability of breeding, and higher fecundity, herbivore-mediated changes in the distribution grazing lawn extent may result in a numerical increase of the population within the next two decades.

Optimizing placements of ground-based snow sensors for areal snow cover estimation using a machine-learning algorithm and melt-season snow-LiDAR data

NASA Astrophysics Data System (ADS)

Oroza, C.; Zheng, Z.; Glaser, S. D.; Bales, R. C.; Conklin, M. H.

2016-12-01

We present a structured, analytical approach to optimize ground-sensor placements based on time-series remotely sensed (LiDAR) data and machine-learning algorithms. We focused on catchments within the Merced and Tuolumne river basins, covered by the JPL Airborne Snow Observatory LiDAR program. First, we used a Gaussian mixture model to identify representative sensor locations in the space of independent variables for each catchment. Multiple independent variables that govern the distribution of snow depth were used, including elevation, slope, and aspect. Second, we used a Gaussian process to estimate the areal distribution of snow depth from the initial set of measurements. This is a covariance-based model that also estimates the areal distribution of model uncertainty based on the independent variable weights and autocorrelation. The uncertainty raster was used to strategically add sensors to minimize model uncertainty. We assessed the temporal accuracy of the method using LiDAR-derived snow-depth rasters collected in water-year 2014. In each area, optimal sensor placements were determined using the first available snow raster for the year. The accuracy in the remaining LiDAR surveys was compared to 100 configurations of sensors selected at random. We found the accuracy of the model from the proposed placements to be higher and more consistent in each remaining survey than the average random configuration. We found that a relatively small number of sensors can be used to accurately reproduce the spatial patterns of snow depth across the basins, when placed using spatial snow data. Our approach also simplifies sensor placement. At present, field surveys are required to identify representative locations for such networks, a process that is labor intensive and provides limited guarantees on the networks' representation of catchment independent variables.

Evaluating long-term patterns of decreasing groundwater discharge through a lake-bottom permeable reactive barrier.

PubMed

McCobb, Timothy D; Briggs, Martin A; LeBlanc, Denis R; Day-Lewis, Frederick D; Johnson, Carole D

2018-05-18

Identifying and quantifying groundwater exchange is critical when considering contaminant fate and transport at the groundwater/surface-water interface. In this paper, areally distributed temperature and point seepage measurements are used to efficiently assess spatial and temporal groundwater discharge patterns through a glacial-kettle lakebed area containing a zero-valent iron permeable reactive barrier (PRB). Concern was that the PRB was becoming less permeable with time owing to biogeochemical processes within the PRB. Patterns of groundwater discharge over an 8-year period were examined using fiber-optic distributed temperature sensing (FO-DTS) and snapshot-in-time point measurements of temperature. The resulting thermal maps show complex and uneven distributions of temperatures across the lakebed and highlight zones of rapid seepage near the shoreline and along the outer boundaries of the PRB. Repeated thermal mapping indicates an increase in lakebed temperatures over time at periods of similar stage and surface-water temperature. Flux rates in six seepage meters permanently installed on the lakebed in the PRB area decreased on average by 0.021 md -1 (or about 4.5 percent) annually between 2004 and 2015. Modeling of diurnal temperature signals from shallow vertical profiles yielded mean flux values ranging from 0.39 to 1.15 md -1 , with stronger fluxes generally related to colder lakebed temperatures. The combination of an increase in lakebed temperatures, declines in direct seepage, and observations of increased cementation of the lakebed surface provide in situ evidence that the permeability of the PRB is declining. The presence of temporally persistent rapid seepage zones is also discussed. Published by Elsevier Ltd.

Assessment of ground-water contamination near Lantana landfill, Southeast Florida

USGS Publications Warehouse

Russell, G.M.; Higer, A.L.

1988-01-01

The Lantana landfill located in Palm Beach County rises 40 to 50 feet above normal ground level and consists of about 250 acres of compacted garbage and trash, some below the water table. Surface-resistivity measurements and water-quality analyses indicate a contaminant plume along the eastern perimeter of the landfill that has migrated about 300 feet eastward toward an adjacent lake. Concentrations of chloride, ammonia, and nitrate were elevated within the plume. The surficial aquifer consists primarily of sand from 0 to about 68 feet, and sand interbedded with sandstone and limestone from 68 to 220 feet. A slight hydraulic gradient exists, indicating ground-water movement from the landfill toward a lake to the east. Analyses of geoelectric, lithologic, and water-quality data indicate that surface geophysical techniques were successful in determining the areal and vertical extent of leachate migration at this location.The Lantana landfill located in Palm Beach County rises 40 to 50 feet above normal ground level and consists of about 250 acres of compacted garbage and trash, some below the water table. Surface-resistivity measurements and water-quality analyses indicate a contaminant plume along the eastern perimeter of the landfill that has migrated about 300 feet eastward toward an adjacent lake. Concentrations of chloride, ammonia, and nitrate were elevated within the plume. The surficial aquifer consists primarily of sand from 0 to about 68 feet, and sand interbedded with sandstone and limestone from 68 to 220 feet. A slight hydraulic gradient exists, indicating ground-water movement from the landfill toward a lake to the east. Analyses of geoelectric, lithologic, and water-quality data indicate that surface geophysical techniques were successful in determining the areal and vertical extent of leachate migration at this location.

Programmable Liquid Crystal Elastomers Prepared by Thiol-Ene Photopolymerization (Postprint)

DTIC Science & Technology

2015-08-17

defect forms a 2D wrinkling pattern that leads to an areal contraction (Figure 4c,d). Both of these films return to a largely flat state on cooling...photopolymerization. ■ MATERIALS AND METHODS RM82 (1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylben- zene) was purchased from Synthon Chemicals. 1,2...noted. Liquid crystal cells were prepared using methods described elsewhere.10 Briefly for cells patterned using rubbed surfaces, Elvamide was

Mississippi Sound remote sensing study. [NASA Earth Resources Laboratory seasonal experiments

NASA Technical Reports Server (NTRS)

Atwell, B. H.; Thomann, G. C.

1973-01-01

A study of the Mississippi Sound was initiated in early 1971 by personnel of NASA Earth Resources Laboratory. Four separate seasonal experiments consisting of quasi-synoptic remote and surface measurements over the entire area were planned. Approximately 80 stations distributed throughout Mississippi Sound were occupied. Surface water temperature and secchi extinction depth were measured at each station and water samples were collected for water quality analyses. The surface distribution of three water parameters of interest from a remote sensing standpoint - temperature, salinity and chlorophyll content - are displayed in map form. Areal variations in these parameters are related to tides and winds. A brief discussion of the general problem of radiative measurements of water temperature is followed by a comparison of remotely measured temperatures (PRT-5) to surface vessel measurements.

Distribution of Ixodes ricinus L., 1758 and Ixodes persulcatus Shulze, 1930 (Parasitoformes, Ixodidae) in Russia and adjacent countries in view of observable climate changes

NASA Astrophysics Data System (ADS)

Yasyukevich, V. V.; Kazakova, E. V.; Popov, I. O.; Semenov, S. M.

2009-08-01

Possible changes in the area inhabited by the ticks Ixodes ricinus and Ixodes persulcatus, the main transmitters of tick-borne encephalitis and Lyme disease in Russia, caused by temperature changes in 1976-2005 compared to 1946-1975 are discussed. It is shown that these changes could result in some areal expansion of these species. In the European part of Russia, I. ricinus expanded its areal boundaries to the east 100-300 km. I. persulcatus expanded its areal in the Asian part of Russia. Its boundary moved to the north and northeast 100-300 km. Areal expansion both of species has not been observed.

Hydrologic impacts of engineering projects on the Tigris Euphrates system and its marshlands

NASA Astrophysics Data System (ADS)

Jones, C.; Sultan, M.; Yan, E.; Milewski, A.; Hussein, M.; Al-Dousari, A.; Al-Kaisy, S.; Becker, R.

2008-05-01

SummaryRising demands for fresh water supplies are leading to water management practices that are altering natural flow systems world-wide. One of the most devastated of these natural systems is the Tigris-Euphrates watershed that over the past three decades has witnessed the construction of over 60 engineering projects that eliminated seasonal flooding, reduced natural flow and dramatically reduced the areal extent (1966: 8000 km 2; 2002: 750 km 2) of the Mesopotamian Marshes downstream. We constructed a catchment-based continuous (1964-1998) rainfall runoff model for the watershed (area: 10 6 km 2) using the Soil Water Assessment Tool (SWAT) model to understand the dynamics of the natural flow system, and to investigate the impacts of reduced overall flow and the related land cover and landuse change downstream in the marshes. The model was calibrated (1964-1970) and validated (1971-1998) against stream flow gauge data. Using the calibrated model we calculated the temporal variations in the average monthly flow rate (AMFR), the average monthly peak flow rate (AMPFR), and annual flow volume (AFV) of the Tigris and Euphrates into the marshes at a location near Al-Basrah city (31°N, 47.5°E) throughout the modeled period. Model results indicate that the AMPFR (6301 m 3/s) and average annual flow volume (AAFV: 80 × 10 9 m 3/yr) for period A (10/1/1965-09/30/1973), preceding the construction of the major dams is progressively diminished in periods B1 (10/1/1973-09/30/1989; AMPFR: 3073 m 3/s; AAFV: 55 × 10 9 m 3/yr) and B2 (10/1/1989-09/30/1998; AMPFR, 2319 m 3/s; AAFV: 50 × 10 9 m 3/yr) that witnessed the construction of the major dams (B1: Keban, Tabqa, Hamrin, Haditha, Mosul, Karakaya; B2: Ataturk) due to the combined effects of filling artificial lakes, evaporation and infiltration of impounded water and its utilization for irrigation purposes. To investigate the impacts of reduced flow on the areal extent of the marshes, we examined the variation in marsh size extracted from temporal satellite data (1966, 1975, 1976, 1977, 1984, 1985, 1986, 1987) acquired around the same approximate time period (July to September) of the year versus simulated AFV for the period preceding the onset (1987) of major local engineering projects (e.g., Crown of Battles River, Loyalty to the Leader Canal, Mother of Battles River) in and around the investigated marshes. Results indicate that the areal extent of the Central and Al-Hammar marshes (e.g., 1966: 7970 km 2, 1977: 6680 km 2, 1984: 5270 km 2) decreases with a decrease in AFV (e.g., 1966: 60.8 × 10 9 m 3, 1977: 56.9 × 10 9 m 3, 1984: 37.6 × 10 9 m 3). Using a relationship that describes the impact of reduced AFV on the areal extent of the marshes, we evaluated the impact of additional reductions in flow that will result from the implementation of the planned engineering projects on the Tigris-Euphrates system over the next few years. Upon completion of the ongoing South Eastern Anatolia project, with projected reductions in AFV exceeding 5 × 10 9 m 3/yr, the sustainable marshes in the Central and Al-Hammar area will be reduced by at least an additional 550 km 2.

Using multiple secondary fusion products to evaluate fuel ρR, electron temperature, and mix in deuterium-filled implosions at the NIF

DOE PAGES

Rinderknecht, H. G.; Rosenberg, M. J.; Zylstra, A. B.; ...

2015-08-25

In deuterium-filled inertial confinement fusion implosions, the secondary fusion processes D( 3He,p) 4He and D(T,n) 4He occur, as the primary fusion products 3He and T react in flight with thermal deuterons. In implosions with moderate fuel areal density (~ 5–100 mg/cm 2), the secondary D- 3He reaction saturates, while the D-T reaction does not, and the combined information from these secondary products is used to constrain both the areal density and either the plasma electron temperature or changes in the composition due to mix of shell material into the fuel. The underlying theory of this technique is developed and appliedmore » to three classes of implosions on the National Ignition Facility: direct-drive exploding pushers, indirect-drive 1-shock and 2-shock implosions,and polar direct-drive implosions. In the 1- and 2-shock implosions, the electron temperature is inferred to be 0.65 x and 0.33 x the burn-averaged ion temperature, respectively. The inferred mixed mass in the polar direct-drive implosions is in agreement with measurements using alternative techniques.« less

Flight Testing Surfaces Engineered for Mitigating Insect Adhesion on a Falcon HU-25C

NASA Technical Reports Server (NTRS)

Shanahan, Michelle; Wohl, Chris J.; Smith, Joseph G., Jr.; Connell, John W.; Siochi, Emilie J.; Doss, Jereme R.; Penner, Ronald K.

2015-01-01

Insect residue contamination on aircraft wings can decrease fuel efficiency in aircraft designed for natural laminar flow. Insect residues can cause a premature transition to turbulent flow, increasing fuel burn and making the aircraft less environmentally friendly. Surfaces, designed to minimize insect residue adhesion, were evaluated through flight testing on a Falcon HU-25C aircraft flown along the coast of Virginia and North Carolina. The surfaces were affixed to the wing leading edge and the aircraft remained at altitudes lower than 1000 feet throughout the flight to assure high insect density. The number of strikes on the engineered surfaces was compared to, and found to be lower than, untreated aluminum control surfaces flown concurrently. Optical profilometry was used to determine insect residue height and areal coverage. Differences in results between flight and laboratory tests suggest the importance of testing in realistic use environments to evaluate the effectiveness of engineered surface designs.

Surface texture measurement for dental wear applications

NASA Astrophysics Data System (ADS)

Austin, R. S.; Mullen, F.; Bartlett, D. W.

2015-06-01

The application of surface topography measurement and characterization within dental materials science is highly active and rapidly developing, in line with many modern industries. Surface measurement and structuring is used extensively within oral and dental science to optimize the optical, tribological and biological performance of natural and biomimetic dental materials. Although there has historically been little standardization in the use and reporting of surface metrology instrumentation and software, the dental industry is beginning to adopt modern areal measurement and characterization techniques, especially as the dental industry is increasingly adopting digital impressioning techniques in order to leverage CAD/CAM technologies for the design and construction of dental restorations. As dental treatment becomes increasingly digitized and reliant on advanced technologies such as dental implants, wider adoption of standardized surface topography and characterization techniques will become evermore essential. The dental research community welcomes the advances that are being made in surface topography measurement science towards realizing this ultimate goal.

A thundercloud electric field sounding - Charge distribution and lightning

NASA Technical Reports Server (NTRS)

Weber, M. E.; Few, A. A.; Stewart, M. F.; Christian, H. J.

1982-01-01

An instrumented free balloon measured electric fields and field changes as it rose through a thundercloud above Langmuir Laboratory, New Mexico. The variation of the electric field with altitude implied that the cloud contained negative space charge of density -0.6 to -4 nC/cu m between 5.5 and 8.0 km MSL. The environmental temperature at these levels ranged from -5 to -20 C. The measurements imply that the areal extent of this negative charge center was significantly greater than that of the cloud's intense precipitation shafts. At altitudes greater than 8 km, the instrument ascended past net positive charge. In addition, positive space charge adjacent to the earth's surface (concentration 0.6 nC/cu m and in the lowest portion of the cloud (1.0 nC/cu m) is inferred from the measurements. Electric field changes from intracloud lightning were interpreted by using a simple model for the developing streamer of the initial phase. Thunder source reconstructions provided estimates for the orientation of lightning channels. Seven 'streamers' so analyzed propagated on the average, at 50,000 m/s and carried a current of 390 A. The mean charge dissipated during a flash was 30 C.

Plasticity of Sorghum Stem Biomass Accumulation in Response to Water Deficit: A Multiscale Analysis from Internode Tissue to Plant Level

PubMed Central

Perrier, Lisa; Rouan, Lauriane; Jaffuel, Sylvie; Clément-Vidal, Anne; Roques, Sandrine; Soutiras, Armelle; Baptiste, Christelle; Bastianelli, Denis; Fabre, Denis; Dubois, Cécile; Pot, David; Luquet, Delphine

2017-01-01

Sorghum is increasingly used as a biomass crop worldwide. Its genetic diversity provides a large range of stem biochemical composition suitable for various end-uses as bioenergy or forage. Its drought tolerance enables it to reasonably sustain biomass production under water limited conditions. However, drought effect on the accumulation of sorghum stem biomass remains poorly understood which limits progress in crop improvement and management. This study aimed at identifying the morphological, biochemical and histological traits underlying biomass accumulation in the sorghum stem and its plasticity in response to water deficit. Two hybrids (G1, G4) different in stem biochemical composition (G4, more lignified, less sweet) were evaluated during 2 years in the field in Southern France, under two water treatments differentiated during stem elongation (irrigated; 1 month dry-down until an average soil water deficit of -8.85 bars). Plant phenology was observed weekly. At the end of the water treatment and at final harvest, plant height, stem and leaf dry-weight and the size, biochemical composition and tissue histology of internodes at 2–4 positions along the stem were measured. Stem biomass accumulation was significantly reduced by drought (in average 42% at the end of the dry-down). This was due to the reduction of the length, but not diameter, of the internodes expanded during water deficit. These internodes had more soluble sugar but lower lignin and cellulose contents. This was associated with a decrease of the areal proportion of lignified cell wall in internode outer zone whereas the areal proportion of this zone was not affected. All internodes for a given genotype and environment followed a common histochemical dynamics. Hemicellulose content and the areal proportion of inner vs. outer internode tissues were set up early during internode growth and were not drought responsive. G4 exhibited a higher drought sensitivity than G1 for plant height only. At final harvest, the stem dry weight was only 18% lower in water deficit (re-watered) compared to well-watered treatment and internodes growing during re-watering were similar to those on the well-watered plants. These results are being valorized to refine the phenotyping of sorghum diversity panels and breeding populations. PMID:28919904

Decorrelation distance of snow in the Colorado River Basin

NASA Technical Reports Server (NTRS)

Chang, A. T. C.; Chiu, L. S.

1989-01-01

The problem of estimating areal averages from point measurement has been extensively studied by mining engineers and hydrologists. Its application to satellite measurements has recently been introduced. The semivariaogram has been used in many geostatistical applications to estimate spatial structures of observed properties, such as mineral distributions. An examination is made of snow variations in Colorado from daily snow data collected in 11 SNOTEL stations. The associated semivariogram is estimated. The objective is to estimate the spatial structure of the snow field so that the point data can be used for comparison with, and validation for, satellite measurements.

Dimensional nanometrology at the National Physical Laboratory

NASA Astrophysics Data System (ADS)

Yacoot, Andrew; Leach, Richard; Hughes, Ben; Giusca, Claudiu; Jones, Christopher; Wilson, Alan

2008-10-01

The growth in nanotechnology has led to an increased requirement for traceable dimensional measurements of nanometre-sized objects and micrometre-sized objects with nanometre tolerances. To meet this challenge NPL has developed both purpose built instrumentation and added metrology to commercially available equipment. This paper describes the development and use of a selection of these instruments that include: atomic force microscopy, x-ray interferometry, a low force balance, a micro coordinate measuring machine and an areal surface texture measuring instrument.

Hydrologic effects of impoundments in Sherburne National Wildlife Refuge, Minnesota

USGS Publications Warehouse

Brown, R.G.

1984-01-01

The hydrologic effects of proposed impoundments in Sherburne National Wildlife Refuge were found to be insignificant with respect to both ground- and surface-water flow patterns and water quality. Monitoring of water levels in 23 observation wells and of discharge in the St. Francis River during 1980 and 1981 has shown that ground water in the surf icial aquifer responds quickly to areal recharge and subsequently discharges to the St. Francis River. The impoundment of surface water in the refuge was not found to affect water levels in the refuge significantly. The impoundments may affect ground-water-flow systems beneath and adjacent to the impoundments. Quality of ground and surface water was found to be similar except ground water contained higher concentrations of dissolved nitrite plus nitrate nitrogen than surface water. Phytoplankton removed dissolved nitrite plus nitrate nitrogen from surface water. The effects of impoundments on water quality are expected to be minor.

Distribution and interplay of geologic processes on Titan from Cassini radar data

USGS Publications Warehouse

Lopes, R.M.C.; Stofan, E.R.; Peckyno, R.; Radebaugh, J.; Mitchell, K.L.; Mitri, Giuseppe; Wood, C.A.; Kirk, R.L.; Wall, S.D.; Lunine, J.I.; Hayes, A.; Lorenz, R.; Farr, Tom; Wye, L.; Craig, J.; Ollerenshaw, R.J.; Janssen, M.; LeGall, A.; Paganelli, F.; West, R.; Stiles, B.; Callahan, P.; Anderson, Y.; Valora, P.; Soderblom, L.

2010-01-01

The Cassini Titan Radar Mapper is providing an unprecedented view of Titan's surface geology. Here we use Synthetic Aperture Radar (SAR) image swaths (Ta-T30) obtained from October 2004 to December 2007 to infer the geologic processes that have shaped Titan's surface. These SAR swaths cover about 20% of the surface, at a spatial resolution ranging from ???350 m to ???2 km. The SAR data are distributed over a wide latitudinal and longitudinal range, enabling some conclusions to be drawn about the global distribution of processes. They reveal a geologically complex surface that has been modified by all the major geologic processes seen on Earth - volcanism, tectonism, impact cratering, and erosion and deposition by fluvial and aeolian activity. In this paper, we map geomorphological units from SAR data and analyze their areal distribution and relative ages of modification in order to infer the geologic evolution of Titan's surface. We find that dunes and hummocky and mountainous terrains are more widespread than lakes, putative cryovolcanic features, mottled plains, and craters and crateriform structures that may be due to impact. Undifferentiated plains are the largest areal unit; their origin is uncertain. In terms of latitudinal distribution, dunes and hummocky and mountainous terrains are located mostly at low latitudes (less than 30??), with no dunes being present above 60??. Channels formed by fluvial activity are present at all latitudes, but lakes are at high latitudes only. Crateriform structures that may have been formed by impact appear to be uniformly distributed with latitude, but the well-preserved impact craters are all located at low latitudes, possibly indicating that more resurfacing has occurred at higher latitudes. Cryovolcanic features are not ubiquitous, and are mostly located between 30?? and 60?? north. We examine temporal relationships between units wherever possible, and conclude that aeolian and fluvial/pluvial/lacustrine processes are the most recent, while tectonic processes that led to the formation of mountains and Xanadu are likely the most ancient. ?? 2009 Elsevier Inc.

Disribution and interplay of geologic processes on Titan from Cassini radar data

USGS Publications Warehouse

Lopes, R.M.C.; Stofan, E.R.; Peckyno, R.; Radebaugh, J.; Mitchell, K.L.; Mitri, Giuseppe; Wood, C.A.; Kirk, R.L.; Wall, S.D.; Lunine, J.I.; Hayes, A.; Lorenz, R.; Farr, Tom; Wye, L.; Craig, J.; Ollerenshaw, R.J.; Janssen, M.; LeGall, A.; Paganelli, F.; West, R.; Stiles, B.; Callahan, P.; Anderson, Y.; Valora, P.; Soderblom, L.

2010-01-01

The Cassini Titan Radar Mapper is providing an unprecedented view of Titan's surface geology. Here we use Synthetic Aperture Radar (SAR) image swaths (Ta-T30) obtained from October 2004 to December 2007 to infer the geologic processes that have shaped Titan's surface. These SAR swaths cover about 20% of the surface, at a spatial resolution ranging from ~350 m to ~2 km. The SAR data are distributed over a wide latitudinal and longitudinal range, enabling some conclusions to be drawn about the global distribution of processes. They reveal a geologically complex surface that has been modified by all the major geologic processes seen on Earth - volcanism, tectonism, impact cratering, and erosion and deposition by fluvial and aeolian activity. In this paper, we map geomorphological units from SAR data and analyze their areal distribution and relative ages of modification in order to infer the geologic evolution of Titan's surface. We find that dunes and hummocky and mountainous terrains are more widespread than lakes, putative cryovolcanic features, mottled plains, and craters and crateriform structures that may be due to impact. Undifferentiated plains are the largest areal unit; their origin is uncertain. In terms of latitudinal distribution, dunes and hummocky and mountainous terrains are located mostly at low latitudes (less than 30 degrees), with no dunes being present above 60 degrees. Channels formed by fluvial activity are present at all latitudes, but lakes are at high latitudes only. Crateriform structures that may have been formed by impact appear to be uniformly distributed with latitude, but the well-preserved impact craters are all located at low latitudes, possibly indicating that more resurfacing has occurred at higher latitudes. Cryovolcanic features are not ubiquitous, and are mostly located between 30 degrees and 60 degrees north. We examine temporal relationships between units wherever possible, and conclude that aeolian and fluvial/pluvial/lacustrine processes are the most recent, while tectonic processes that led to the formation of mountains and Xanadu are likely the most ancient.

Surface segregation effects of erbium in GaAs growth and their implications for optical devices containing ErAs nanostructures

NASA Astrophysics Data System (ADS)

Crook, Adam M.; Nair, Hari P.; Bank, Seth R.

2011-03-01

We report on the integration of semimetallic ErAs nanoparticles with high optical quality GaAs-based semiconductors, grown by molecular beam epitaxy. Secondary ion mass spectrometry and photoluminescence measurements provide evidence of surface segregation and incorporation of erbium into layers grown with the erbium cell hot, despite the closed erbium source shutter. We establish the existence of a critical areal density of the surface erbium layer, below which the formation of ErAs precipitates is suppressed. Based upon these findings, we demonstrate a method for overgrowing ErAs nanoparticles with III-V layers of high optical quality, using subsurface ErAs nanoparticles as a sink to deplete the surface erbium concentration. This approach provides a path toward realizing optical devices based on plasmonic effects in an epitaxially-compatible semimetal/semiconductor system.

Comparison Of Methods Used In Cartography For The Skeletonisation Of Areal Objects

NASA Astrophysics Data System (ADS)

Szombara, Stanisław

2015-12-01

The article presents a method that would compare skeletonisation methods for areal objects. The skeleton of an areal object, being its linear representation, is used, among others, in cartographic visualisation. The method allows us to compare between any skeletonisation methods in terms of the deviations of distance differences between the skeleton of the object and its border from one side and the distortions of skeletonisation from another. In the article, 5 methods were compared: Voronoi diagrams, densified Voronoi diagrams, constrained Delaunay triangulation, Straight Skeleton and Medial Axis (Transform). The results of comparison were presented on the example of several areal objects. The comparison of the methods showed that in all the analysed objects the Medial Axis (Transform) gives the smallest distortion and deviation values, which allows us to recommend it.

Trade-off between Photon Management Efficacy and Material Quality in Thin-Film Solar Cells on Nanostructured Substrates of High Aspect Ratio Structures

DOE PAGES

Chin, Alan; Keshavarz, Majid; Wang, Qi

2018-04-13

Although texturing of the transparent electrode of thin-film solar cells has long been used to enhance light absorption via light trapping, such texturing has involved low aspect ratio features. With the recent development of nanotechnology, nanostructured substrates enable improved light trapping and enhanced optical absorption via resonances, a process known as photon management, in thin-film solar cells. Despite the progress made in the development of photon management in thin-film solar cells using nanostructures substrates, the structural integrity of the thin-film solar cells deposited onto such nanostructured substrates is rarely considered. Here, we report the observation of the reduction in themore » open circuit voltage of amorphous silicon solar cells deposited onto a nanostructured substrate with increasing areal number density of high aspect ratio structures. For a nanostructured substrate with the areal number density of such nanostructures increasing in correlation with the distance from one edge of the substrate, a correlation between the open circuit voltage reduction and the increase of the areal number density of high aspect ratio nanostructures of the front electrode of the small-size amorphous silicon solar cells deposited onto different regions of the substrate with graded nanostructure density indicates the effect of the surface morphology on the material quality, i.e., a trade-off between photon management efficacy and material quality. Lastly, this observed trade-off highlights the importance of optimizing the morphology of the nanostructured substrate to ensure conformal deposition of the thin-film solar cell.« less

Trade-off between Photon Management Efficacy and Material Quality in Thin-Film Solar Cells on Nanostructured Substrates of High Aspect Ratio Structures

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

Chin, Alan; Keshavarz, Majid; Wang, Qi

Although texturing of the transparent electrode of thin-film solar cells has long been used to enhance light absorption via light trapping, such texturing has involved low aspect ratio features. With the recent development of nanotechnology, nanostructured substrates enable improved light trapping and enhanced optical absorption via resonances, a process known as photon management, in thin-film solar cells. Despite the progress made in the development of photon management in thin-film solar cells using nanostructures substrates, the structural integrity of the thin-film solar cells deposited onto such nanostructured substrates is rarely considered. Here, we report the observation of the reduction in themore » open circuit voltage of amorphous silicon solar cells deposited onto a nanostructured substrate with increasing areal number density of high aspect ratio structures. For a nanostructured substrate with the areal number density of such nanostructures increasing in correlation with the distance from one edge of the substrate, a correlation between the open circuit voltage reduction and the increase of the areal number density of high aspect ratio nanostructures of the front electrode of the small-size amorphous silicon solar cells deposited onto different regions of the substrate with graded nanostructure density indicates the effect of the surface morphology on the material quality, i.e., a trade-off between photon management efficacy and material quality. Lastly, this observed trade-off highlights the importance of optimizing the morphology of the nanostructured substrate to ensure conformal deposition of the thin-film solar cell.« less

A fiber matrix model for fluid flow and streaming potentials in the canaliculi of an osteon

NASA Technical Reports Server (NTRS)

Zeng, Y.; Cowin, S. C.; Weinbaum, S.

1994-01-01

A theoretical model is developed to predict the fluid shear stress and streaming potential at the surface of osteocytic processes in the lacunar-canalicular porosity of an osteon when the osteon is subject to mechanical loads that are parallel or perpendicular to its axis. The theory developed in Weinbaum et al. (31) for the flow through a proteoglycan matrix in a canaliculus is employed in a poroelastic model for the osteon. Our formulation is a generalization of that of Petrov et al. (17). Our model predicts that, in order to satisfy the measured frequency dependence of the phase and magnitude of the SGP in macroscopic bone samples, the fiber spacing in the fluid annulus must lie in the narrow range 6-7 nm typical of the spacing of GAG sidechains along a protein monomer. The model predictions for the local SGP profiles in the osteon agree with the experimental observations of Starkebaum et al. (24). The theory predicts that the pore pressure relaxation time, tau d, for a 150-300 microns diameter osteon with the foregoing matrix structure is approximately 0.03-0.13 sec, and that the amplitude of the mean fluid shear stress on the membrane of the osteocytic process at the mean areal radius of the osteon has a maximum at 28 Hz if tau d = 0.06 sec. This maximum, which is independent of the magnitude of the loading, could be important in vivo since the recent experiments of Turner et al. (28) and McLeod et al. (15) have a peak in the strain frequency spectrum between 20 and 30 Hz that also appears to be independent of the type (magnitude) of loading. Numerical predictions for the amplitude of the average fluid shear stress on the osteocytic membrane at the mean areal radius of the osteon show that the fluid shear stress associated with the low amplitude 20-30 Hz spectral strain component is at least as large as the average fluid shear stress associated with the high amplitude 1 Hz stride component, although the latter loading is an order of magnitude larger, and has a magnitude that lies within the middle of the range, 6-30 dynes/cm2, where fluid shear stresses in tissue culture studies with osteoblast monolayers have elicited an intracellular Ca++ response (31). The implications of these results for intracellular electrical communication are discussed.

Using daily temperature to predict phenology trends in spring flowers

NASA Astrophysics Data System (ADS)

Kim, Jin-Hee; Kim, Soo-Ock; Kim, Dae-Jun; Moon, Kyung Hwan; Yun, Jin I.

2015-05-01

The spring season in Korea features a dynamic landscape with a variety of flowers blooming sequentially one after another. This enables local governments to earn substantial sightseeing revenues by hosting festivals featuring spring flowers. Furthermore, beekeepers move from the southern tip of the Korean Peninsula all the way northward in a quest to secure spring flowers as nectar sources for a sustained period of time. However, areal differences in flowering dates of flower species are narrowing, which has economic consequences. Analysis of data on flowering dates of forsythia ( Forsythia koreana) and cherry blossom ( Prunus serrulata), two typical spring flower species, as observed for the past 60 years at six weather stations of the Korea Meteorological Administration (KMA) indicated that the difference between the flowering date of forsythia, the earliest blooming flower in spring, and cherry blossom, which flowers later than forsythia, was 14 days on average in the climatological normal year for the period 1951-1980, compared with 11 days for the period 1981-2010. In 2014, the gap narrowed further to 7 days, making it possible in some locations to see forsythias and cherry blossoms blooming at the same time. Synchronized flowering of these two flower species is due to acceleration of flowering due to an abnormally high spring temperature, and this was more pronounced in the later-blooming cherry blossom than forsythia. While cherry blossom flowering dates across the nation ranged from March 31 to April 19 (an areal difference of 20 days) for the 1951-1980 normal year, the difference ranged from March 29 to April 12 (an areal difference of 16 days) for the 1981-2010 normal year, and in 2014, the flowering dates spanned March 25 and March 30 (an areal difference of 6 days). In the case of forsythia, the gap was narrower than in cherry blossoms. Climate change in the Korean Peninsula, reflected by rapid temperature hikes in late spring in contrast to a slow temperature rise in early spring immediately after dormancy release, likely brought forward the flowering date of cherry blossom. We derived a thermal time-based flowering model from this analysis and used it to predict the flowering dates of forsythia and cherry blossom in 2014. The root mean square error for the prediction was within 2 days from the observed flowering dates in both species, showing a feasibility of prediction under the changing climate.

Flexible supercapacitors with high areal capacitance based on hierarchical carbon tubular nanostructures

NASA Astrophysics Data System (ADS)

Zhang, Haitao; Su, Hai; Zhang, Lei; Zhang, Binbin; Chun, Fengjun; Chu, Xiang; He, Weidong; Yang, Weiqing

2016-11-01

Hierarchical structure design can greatly enhance the unique properties of primary material(s) but suffers from complicated preparation process and difficult self-assembly of materials with different dimensionalities. Here we report on the growth of single carbon tubular nanostructures with hierarchical structure (hCTNs) through a simple method based on direct conversion of carbon dioxide. Resorting to in-situ transformation and self-assembly of carbon micro/nano-structures, the obtained hCTNs are blood-like multichannel hierarchy composed of one large channel across the hCTNs and plenty of small branches connected to each other. Due to the unique pore structure and high surface area, these hCTN-based flexible supercapacitors possess the highest areal capacitance of ∼320 mF cm-2, as well as good rate-capability and excellent cycling stability (95% retention after 2500 cycles). It was established that this method can control the morphology, size, and density of hCTNs and effectively construct hCTNs well anchored to the various substrates. Our work unambiguously demonstrated the potential of hCTNs for large flexible supercapacitors and integrated energy management electronics.

Genetic and environmental determinants of volumetric and areal BMD in multi-generational families of African ancestry: the Tobago Family Health Study.

PubMed

Wang, Xiaojing; Kammerer, Candace M; Wheeler, Victor W; Patrick, Alan L; Bunker, Clareann H; Zmuda, Joseph M

2007-04-01

BMD is higher and fracture risk is lower among individuals of African versus European descent, but little is known about the genetic architecture of BMD in the former group. Heritabilities of areal and volumetric BMD were moderate in our large families of African descent but differed for trabecular and cortical BMD. Populations of African ancestry have lower osteoporotic fracture risk and higher BMD than other ethnic groups. However, there is a paucity of information regarding the genetic and environmental influences on bone health among populations of African heritage. We dissected the genetic architecture of areal BMD measured by DXA at the proximal femur, lumbar spine, and whole body and volumetric BMD measured by pQCT at the distal and proximal radius and tibia in 283 women and 188 men > or =18 years of age (mean, 43 years) from eight multigenerational Afro-Caribbean families (mean family size > 50). Using quantitative genetic methods, we estimated the residual heritability and the effects of anthropometric, demographic, lifestyle, and medical variables on areal and volumetric BMD. Compared with U.S. non-Hispanic blacks and whites, areal BMD at the femoral neck was highest in the Afro-Caribbean men and women at all ages. Trabecular volumetric BMD decreased linearly with increasing age, whereas cortical volumetric BMD did not decrease until age 40-49, especially in women. Anthropometric, lifestyle, and medical factors accounted for 12-32% of the variation in areal and volumetric BMD, and residual heritabilities (range, 0.23-0.52) were similar to those reported in other ethnic groups. Heritability of cortical BMD was substantially lower than that of areal or trabecular volumetric BMD, although the measured covariates accounted for a similar proportion of the total phenotypic variation. Our study is the first comprehensive genetic epidemiologic analysis of volumetric BMD measured by QCT and the first analysis of these traits in extended families of African descent. Genes account for as much or more of the total variation in areal and volumetric BMD than do environmental factors, but these effects seem to differ for trabecular and cortical bone.

Three-dimensional numerical model of ground-water flow in northern Utah Valley, Utah County, Utah

USGS Publications Warehouse

Gardner, Philip M.

2009-01-01

A three-dimensional, finite-difference, numerical model was developed to simulate ground-water flow in northern Utah Valley, Utah. The model includes expanded areal boundaries as compared to a previous ground-water flow model of the valley and incorporates more than 20 years of additional hydrologic data. The model boundary was generally expanded to include the bedrock in the surrounding mountain block as far as the surface-water divide. New wells have been drilled in basin-fill deposits near the consolidated-rock boundary. Simulating the hydrologic conditions within the bedrock allows for improved simulation of the effect of withdrawal from these wells. The inclusion of bedrock also allowed for the use of a recharge model that provided an alternative method for spatially distributing areal recharge over the mountains.The model was calibrated to steady- and transient-state conditions. The steady-state simulation was developed and calibrated by using hydrologic data that represented average conditions for 1947. The transient-state simulation was developed and calibrated by using hydrologic data collected from 1947 to 2004. Areally, the model grid is 79 rows by 70 columns, with variable cell size. Cells throughout most of the model domain represent 0.3 mile on each side. The largest cells are rectangular with dimensions of about 0.3 by 0.6 mile. The largest cells represent the mountain block on the eastern edge of the model domain where the least hydrologic data are available. Vertically, the aquifer system is divided into 4 layers which incorporate 11 hydrogeologic units. The model simulates recharge to the ground-water flow system as (1) infiltration of precipitation over the mountain block, (2) infiltration of precipitation over the valley floor, (3) infiltration of unconsumed irrigation water from fields, lawns, and gardens, (4) seepage from streams and canals, and (5) subsurface inflow from Cedar Valley. Discharge of ground water is simulated by the model to (1) flowing and pumping wells, (2) drains and springs, (3) evapotranspiration, (4) Utah Lake, (5) the Jordan River and mountain streams, and (6) Salt Lake Valley by subsurface outflow through the Jordan Narrows.During steady-state calibration, variables were adjusted within probable ranges to minimize differences between model-computed and measured water levels as well as between model-computed and independently estimated flows that include: recharge by seepage from individual streams and canals, discharge by seepage to individual streams and the Jordan River, discharge to Utah Lake, discharge to drains and springs, discharge by evapotranspiration, and subsurface flows into and out of northern Utah Valley from Cedar Valley and to Salt Lake Valley, respectively. The transient-state simulation was calibrated to measured water levels and water-level changes with consideration given to annual changes in the flows listed above.

Analysis of Surface Fluxes at Eureka Climate Observatory in Arctic

NASA Astrophysics Data System (ADS)

Grachev, Andrey; Albee, Robert; Fairall, Christopher; Hare, Jeffrey; Persson, Ola; Uttal, Taneil

2010-05-01

The Arctic region is experiencing unprecedented changes associated with increasing average temperatures (faster than the pace of the globally-averaged increase) and significant decreases in both the areal extent and thickness of the Arctic pack ice. These changes are early warning signs of shifts in the global climate system that justifies increased scientific focus on this region. The increase in atmospheric carbon dioxide has raised concerns worldwide about future climate change. Recent studies suggest that huge stores of carbon dioxide (and other climate relevant compounds) locked up in Arctic soils could be unexpectedly released due to global warming. Observational evidence suggests that atmospheric energy fluxes are a major contributor to the decrease of the Arctic pack ice, seasonal land snow cover and the warming of the surrounding land areas and permafrost layers. To better understand the atmosphere-surface exchange mechanisms, improve models, and to diagnose climate variability in the Arctic, accurate measurements are required of all components of the net surface energy budget and the carbon dioxide cycle over representative areas and over multiple years. In this study we analyze variability of turbulent fluxes including water vapor and carbon dioxide transfer based on long-term measurements made at Eureka observatory (80.0 N, 85.9 W) located near the coast of the Arctic Ocean (Canadian territory of Nunavut). Turbulent fluxes and mean meteorological data are continuously measured and reported hourly at various levels on a 10-m flux tower. Sonic anemometers are located at 3 and 8 m heights while high-speed Licor 7500 infrared gas analyzer (water moisture and carbon dioxide measurements) at 7.5 m height. According to our data, that the sensible heat flux, carbon dioxide and water vapor fluxes exhibited clear diurnal cycles in Arctic summer. This behavior is similar to the diurnal variation of the fluxes in mid-latitudes during the plants growing season, with carbon dioxide uptake from the atmosphere during the day due to photosynthesis, and carbon dioxide loss to the atmosphere due to vegetation respiration during the night. However, at Eureka vegetation was a source of carbon dioxide during sunlit periods. Thus the sign of carbon dioxide flux was controlled by air temperature even during Arctic summer.

Effect of seasonal and long-term changes in stress on sources of water to wells

USGS Publications Warehouse

Reilly, Thomas E.; Pollock, David W.

1995-01-01

The source of water to wells is ultimately the location where the water flowing to a well enters the boundary surface of the ground-water system . In ground-water systems that receive most of their water from areal recharge, the location of the water entering the system is at the water table . The area contributing recharge to a discharging well is the surface area that defines the location of the water entering the groundwater system. Water entering the system at the water table flows to the well and is eventually discharged from the well. Many State agencies are currently (1994) developing wellhead-protection programs. The thrust of some of these programs is to protect water supplies by determining the areas contributing recharge to water-supply wells and by specifying regulations to minimize the opportunity for contamination of the recharge water by activities at the land surface. In the analyses of ground-water flow systems, steady-state average conditions are frequently used to simplify the problem and make a solution tractable. Recharge is usually cyclic in nature, however, having seasonal cycles and longer term climatic cycles. A hypothetical system is quantitatively analyzed to show that, in many cases, these cyclic changes in the recharge rates apparently do not significantly affect the location and size of the areas contributing recharge to wells. The ratio of the mean travel time to the length of the cyclic stress period appears to indicate whether the transient effects of the cyclic stress must be explicitly represented in the analysis of contributing areas to wells. For the cases examined, if the ratio of the mean travel time to the period of the cyclic stress was much greater than one, then the transient area contributing recharge to wells was similar to the area calculated using an average steady-state condition. Noncyclic long-term transient changes in water use, however, and cyclic stresses on systems with ratios less than 1 can and do affect the location and size of the areas contributing recharge to wells.

Io's Heat Flow: A Model Including "Warm" Polar Regions

NASA Astrophysics Data System (ADS)

Veeder, G. J.; Matson, D. L.; Johnson, T. V.; Davies, A. G.; Blaney, D. L.

2002-12-01

Some 90 percent of Io's surface is thermally "passive" material. It is separate from the sites of active volcanic eruptions. Though "passive", its thermal behavior continues to be a challenge for modelers. The usual approach is to take albedo, average daytime temperature, temperature as a function of time of day, etc., and attempt to match these constraints with a uniform surface with a single value of thermal inertia. Io is a case where even globally averaged observations are inconsistent with a single-thermal-inertia model approach. The Veeder et al. (1994) model for "passive" thermal emission addressed seven constraints derived from a decade of ground-based, global observations - average albedo plus infrared fluxes at three separate wavelengths (4.8, 8.7, and 20 microns) for both daytime and eclipsed conditions. This model has only two components - a unit of infinite thermal inertia and a unit of zero thermal inertia. The free parameters are the areal coverage ratio of the two units and their relative albedos (constrained to match the known average albedo). This two-parameter model agreed with the global radiometric data and also predicted significantly higher non-volcanic nighttime temperatures than traditional ("lunar-like") single thermal inertia models. Recent observations from the Galileo infrared radiometer show relatively uniform minimum-night-time temperatures. In particular, they show little variation with either latitude or time of night (Spencer et al., 2000; Rathbun et al., 2002). Additionally, detailed analyses of Io's scattering properties and reflectance variations have led to the interesting conclusion that Io's albedo at regional scales varies little with latitude (Simonelli, et al., 2001). This effectively adds four new observational constraints - lack of albedo variation with latitude, average minimum nighttime temperature and lack of variation of temperature with either latitude or longitude. We have made the fewest modifications necessary for the Veeder et al. model to match these new constrains - we added two model parameters to characterize the volcanically heated high-latitude units. These are the latitude above which the unit exists and its nighttime temperature. The resulting four-parameter model is the first that encompasses all of the available observations of Io's thermal emission and that quantitatively satisfies all eleven observational constraints. While no model is unique, this model is significant because it is the first to accommodate widespread polar regions that are relatively "warm". This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA.

Are the dimensions of submarine lobe systems independent of allogenic factors?

NASA Astrophysics Data System (ADS)

Prélat, A.; Covault, J. A.; Hodgson, D. M.; Fildani, A.; Flint, S. S.

2010-05-01

Submarine lobe dimensions from six different systems are compared: 1) the exhumed Permian Fan 3 lobe complex of the Tanqua Karoo, South Africa; 2) the modern Amazon fan channel-mouth lobe complex, offshore Brazil; 3) a portion of the modern distal Zaïre fan, offshore Angola / Congo; 4) a Pleistocene fan of the Kutai Basin, subsurface offshore Indonesia; 5) the modern Golo system, offshore east Corsica, France; and 6) a lobe complex deposited in the shallow subsurface, offshore Nigeria. These six systems have significantly different source-to-sink configurations (shelf dimension and slope topography), sediment supply characteristics (calibre and rate), tectonic settings, (palaeo) latitude, and delivery systems. Despite these differences, the lobe deposits share similar geometric and dimensional characteristics. Lobes are grouped into two distinct populations of geometries that can be related to basin-floor topography. The first population corresponds to areally extensive but thin lobes (average width 14 km × length 35 km × thickness 12 m) that were deposited onto low relief basin floor areas, like the Tanqua Karoo, the Amazon and the Zaïre systems. The second population corresponds to areally smaller but thicker lobes (average width 5 km × length 8 km × thickness 30 m) that were deposited into settings with higher amplitude of relief, like in the Corsican trough, the Kutai basin, and offshore Nigeria. Basin floor topography confining the lobes can be very subtle, and only occur on one side of the system. The two populations of lobe types, however, share similar volumes, in the order of 1 or 2 km3. The largest lobes are observed in the Zaïre fan, where the average lobe volume reaches 3.3 km3 and the smallest lobes are observed in the Corsican trough where the average lobe volume is 0.4 km3. This variation in lobe volume is minor when compared to the variation observed in present-day up-dip drainage systems, which provide sediment to the deep-water depositional systems and their lobes. This suggests that there is a limit to the total volume of sediment that individual lobes can reach before they shift to a new locus of deposition. In otherwords, big systems do not build big lobes, rather more lobes per unit time. Indeed, in the Amazon and the Zaïre systems, lobe life span is estimated to be 600 and 1450 years, respectively, whereas in the Corsican Golo system, lobe life span is ~ 10 times longer, around 10 to 14 × 103 years. A fundamental control on lobe volume is the propensity for flows to find the lowest topography. We postulate that a fundamental control on all distributive systems is the ratio of lobe thickness to feeder channel depth. The surface gradient from the feeder channel base and lobe top will tend to reduce through time as a lobe builds. This is not sustainable, and when a steeper lateral gradient is present a new depositional low will be used for flows to fill.

Studies of ice sheet hydrology using SAR

NASA Technical Reports Server (NTRS)

Bindschadler, R. A.; Vornberger, P. L.

1989-01-01

Analysis of SAR data of the Greenland ice sheet in summer and winter suggest the use of SAR to monitor the temporal hydrology of ice sheets. Comparisons of each SAR data set with summer Landsat TM imagery show an areal-positive correlation with summer SAR data and a negative correlation with winter SAR data. It is proposed that the summer SAR data are most sensitive to the variable concentrations of free water in the surface snow and that the winter SAR data indicate variations in snow grain size.

The use of ERTS imagery in reservoir management and operation

NASA Technical Reports Server (NTRS)

Cooper, S. (Principal Investigator)

1973-01-01

There are no author-identified significant results in this report. Preliminary analysis of ERTS-1 imagery suggests that the configuration and areal coverage of surface waters, as well as other hydrologically related terrain features, may be obtained from ERTS-1 imagery to an extent that would be useful. Computer-oriented pattern recognition techniques are being developed to help automate the identification and analysis of hydrologic features. Considerable man-machine interaction is required while training the computer for these tasks.

Statistical pattern analysis of surficial karst in the Pleistocene Miami oolite of South Florida

NASA Astrophysics Data System (ADS)

Harris, Paul (Mitch); Purkis, Sam; Reyes, Bella

2018-05-01

A robust airborne light detection and ranging digital terrain model (LiDAR DTM) and select outcrops are used to examine the extent and characteristics of the surficial karst overprint of the late Pleistocene Miami oolite in South Florida. Subaerial exposure of the Miami oolite barrier bar and shoals to a meteoric diagenetic environment, lasting ca. 120 kyr from the end of the last interglacial highstand MIS 5e until today, has resulted in diagenetic alteration including surface and shallow subsurface dissolution producing extensive dolines and a few small stratiform caves. Analysis of the LiDAR DTM suggests that >50% of the dolines in the Miami oolite have been obscured/lost to urbanization, though a large number of depressions remain apparent and can be examined for trends and spatial patterns. The verified dolines are analyzed for their size and depth, their lateral distribution and relation to depositional topography, and the separation distance between them. Statistical pattern analysis shows that the average separation distance and average density of dolines on the strike-oriented barrier bar versus dip-oriented shoals is statistically inseparable. Doline distribution on the barrier bar is clustered because of the control exerted on dissolution by the depositional topography of the shoal system, whereas patterning of dolines in the more platform-ward lower-relief shoals is statistically indistinguishable from random. The areal extent and depth of dissolution of the dolines are well described by simple mathematical functions, and the depth of the dolines increases as a function of their size. The separation and density results from the Miami oolite are compared to results from other carbonate terrains. Near-surface, stratiform caves in the Miami oolite occur in sites where the largest and deepest dolines are present, and sit at, or near, the top of the present water table.

The Effect of Geographic Units of Analysis on Measuring Geographic Variation in Medical Services Utilization.

PubMed

Kim, Agnus M; Park, Jong Heon; Kang, Sungchan; Hwang, Kyosang; Lee, Taesik; Kim, Yoon

2016-07-01

We aimed to evaluate the effect of geographic units of analysis on measuring geographic variation in medical services utilization. For this purpose, we compared geographic variations in the rates of eight major procedures in administrative units (districts) and new areal units organized based on the actual health care use of the population in Korea. To compare geographic variation in geographic units of analysis, we calculated the age-sex standardized rates of eight major procedures (coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, surgery after hip fracture, knee-replacement surgery, caesarean section, hysterectomy, computed tomography scan, and magnetic resonance imaging scan) from the National Health Insurance database in Korea for the 2013 period. Using the coefficient of variation, the extremal quotient, and the systematic component of variation, we measured geographic variation for these eight procedures in districts and new areal units. Compared with districts, new areal units showed a reduction in geographic variation. Extremal quotients and inter-decile ratios for the eight procedures were lower in new areal units. While the coefficient of variation was lower for most procedures in new areal units, the pattern of change of the systematic component of variation between districts and new areal units differed among procedures. Geographic variation in medical service utilization could vary according to the geographic unit of analysis. To determine how geographic characteristics such as population size and number of geographic units affect geographic variation, further studies are needed.

Modelling Cryovolcanism Due to Subsurface Ocean Freezing on Pluto and Charon

NASA Astrophysics Data System (ADS)

Conrad, J. W.; Nimmo, F.; Singer, K. N.

2016-12-01

The New Horizons spacecraft identified various possible cryovolcanic features on the surfaces of both Pluto and Charon [1]. However, there are major differences between the cryovolcanism on Pluto and Charon. Pluto has two mound-flanked depressions which are possibly cryovolcanic [2], while Charon's putative cryovolcanism is more widespread within its smooth southern plains. If Pluto or Charon have (or had) subsurface oceans, slow refreezing of these oceans would lead to extensional surface tectonics [3,4] and pressurization of the ocean [5]. Sufficiently large pressurization can overcome the overburden pressure and cause an eruption. We applied thermal evolution models based on [3] to determine likely freezing scenarios. Eruptions on Charon are possible under most conditions, and occur after tens of kilometers of freezing of an ice shell initially 100 km thick. This would produce an areal extensional strain of 1%. The implied globally-averaged thickness of erupted material is a few hundred meters and the critical crack width for propagation through the entire ice shell [6] is about half a meter for all eruption scenarios. Eruptions on Pluto require probably unrealistic freezing scenarios, because of the larger body size and higher overburden pressure. We conclude that ocean freezing is a possible source of cryovolcanism on Charon and may explain the smooth plains in its southern hemisphere [1]. Pluto, on the other hand, requires more complex models to explain the putative cryovolcanic features on its surface. [1] Moore et al., Science 351 (2016): 1284-1293. [2] Singer et al., LPSC 47 (2016): 2276 [3] Robuchon and Nimmo, Icarus 216 (2011): 426-439. [4] Hammond et al., GRL 43 (2016). [5] Manga and Wang, GRL 34 (2007). [6] Porco et al., The Astronomical Journal 148 (2014): 45.

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.

Areal-averaged trace gas emission rates from long-range open-path measurements in stable boundary layer conditions

NASA Astrophysics Data System (ADS)

Schäfer, K.; Grant, R. H.; Emeis, S.; Raabe, A.; von der Heide, C.; Schmid, H. P.

2012-07-01

Measurements of land-surface emission rates of greenhouse and other gases at large spatial scales (10 000 m2) are needed to assess the spatial distribution of emissions. This can be readily done using spatial-integrating micro-meteorological methods like flux-gradient methods which were evaluated for determining land-surface emission rates of trace gases under stable boundary layers. Non-intrusive path-integrating measurements are utilized. Successful application of a flux-gradient method requires confidence in the gradients of trace gas concentration and wind, and in the applicability of boundary-layer turbulence theory; consequently the procedures to qualify measurements that can be used to determine the flux is critical. While there is relatively high confidence in flux measurements made under unstable atmospheres with mean winds greater than 1 m s-1, there is greater uncertainty in flux measurements made under free convective or stable conditions. The study of N2O emissions of flat grassland and NH3 emissions from a cattle lagoon involves quality-assured determinations of fluxes under low wind, stable or night-time atmospheric conditions when the continuous "steady-state" turbulence of the surface boundary layer breaks down and the layer has intermittent turbulence. Results indicate that following the Monin-Obukhov similarity theory (MOST) flux-gradient methods that assume a log-linear profile of the wind speed and concentration gradient incorrectly determine vertical profiles and thus flux in the stable boundary layer. An alternative approach is considered on the basis of turbulent diffusivity, i.e. the measured friction velocity as well as height gradients of horizontal wind speeds and concentrations without MOST correction for stability. It is shown that this is the most accurate of the flux-gradient methods under stable conditions.

Composite materials for precision space reflector panels

NASA Technical Reports Server (NTRS)

Tompkins, Stephen S.; Funk, Joan G.; Bowles, David E.; Towell, Timothy W.; Connell, John W.

1992-01-01

One of the critical technology needs of large precision reflectors for future astrophysical and optical communications satellites lies in the area of structural materials. Results from a materials research and development program at NASA Langley Research Center to provide materials for these reflector applications are discussed. Advanced materials that meet the reflector panel requirements are identified, and thermal, mechanical and durability properties of candidate materials after exposure to simulated space environments are compared. A parabolic, graphite-phenolic honeycomb composite panel having a surface accuracy of 70.8 microinches rms and an areal weight of 1.17 lbm/sq ft was fabricated with T50/ERL1962 facesheets, a PAEI thermoplastic surface film, and Al and SiO(x) coatings.

Global geochemical problems

NASA Technical Reports Server (NTRS)

Harriss, R. C.

1980-01-01

Application of remote sensing techniques to the solution of geochemical problems is considered with emphasis on the 'carbon-cycle'. The problem of carbon dioxide sinks and the areal extent of coral reefs are treated. In order to assess the problems cited it is suggested that remote sensing techniques be utilized to: (1)monitor globally the carbonate and bicarbonate concentrations in surface waters of the world ocean; (2)monitor the freshwater and oceanic biomass and associated dissolved organic carbon; (3) inventory the coral reef areas and types and the associated oceanographic climatic conditions; and (4)measure the heavy metal fluxes from forested and vegetated areas, from volcanos, from different types of crustal rocks, from soils, and from sea surfaces.

Estimation of carbon emissions from wildfires in Alaskan boreal forests using AVHRR data

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

Kasischke, E.S.; French, N.H.F.; Bourgeau-Chavez, L.L

1993-06-01

The objectives of this research study were to evaluate the utility of using AVHRR data for locating and measuring the areal extent of wildfires in the boreal forests of Alaska and to estimate the amount of carbon being released during these fires. Techniques were developed to using the normalized difference vegetation signature derived from AVHRR data to detect and measure the area of fires in Alaska. A model was developed to estimate the amount of biomass/carbon being stored in Alaskan boreal forests, and the amount of carbon released during fires. The AVHRR analysis resulted in detection of > 83% ofmore » all forest fires greater than 2,000 ha in size in the years 1990 and 1991. The areal estimate derived from AVHRR data were 75% of the area mapped by the Alaska Fire Service for these years. Using fire areas and locations for 1954 through 1992, it was determined that on average, 13.0 gm-C-m-2 of boreal forest area is released during fires every year. This estimate is two to six times greater than previous reported estimates. Our conclusions are that the analysis of AVHRR data represents a viable means for detecting and mapping fires in boreal regions on a global basis.« less

The Roles of Cortical Slow Waves in Synaptic Plasticity and Memory Consolidation.

PubMed

Miyamoto, Daisuke; Hirai, Daichi; Murayama, Masanori

2017-01-01

Sleep plays important roles in sensory and motor memory consolidation. Sleep oscillations, reflecting neural population activity, involve the reactivation of learning-related neurons and regulate synaptic strength and, thereby affect memory consolidation. Among sleep oscillations, slow waves (0.5-4 Hz) are closely associated with memory consolidation. For example, slow-wave power is regulated in an experience-dependent manner and correlates with acquired memory. Furthermore, manipulating slow waves can enhance or impair memory consolidation. During slow wave sleep, inter-areal interactions between the cortex and hippocampus (HC) have been proposed to consolidate declarative memory; however, interactions for non-declarative (HC-independent) memory remain largely uninvestigated. We recently showed that the directional influence in a slow-wave range through a top-down cortical long-range circuit is involved in the consolidation of non-declarative memory. At the synaptic level, the average cortical synaptic strength is known to be potentiated during wakefulness and depressed during sleep. Moreover, learning causes plasticity in a subset of synapses, allocating memory to them. Sleep may help to differentiate synaptic strength between allocated and non-allocated synapses (i.e., improving the signal-to-noise ratio, which may facilitate memory consolidation). Herein, we offer perspectives on inter-areal interactions and synaptic plasticity for memory consolidation during sleep.

The Roles of Cortical Slow Waves in Synaptic Plasticity and Memory Consolidation

PubMed Central

Miyamoto, Daisuke; Hirai, Daichi; Murayama, Masanori

2017-01-01

Sleep plays important roles in sensory and motor memory consolidation. Sleep oscillations, reflecting neural population activity, involve the reactivation of learning-related neurons and regulate synaptic strength and, thereby affect memory consolidation. Among sleep oscillations, slow waves (0.5–4 Hz) are closely associated with memory consolidation. For example, slow-wave power is regulated in an experience-dependent manner and correlates with acquired memory. Furthermore, manipulating slow waves can enhance or impair memory consolidation. During slow wave sleep, inter-areal interactions between the cortex and hippocampus (HC) have been proposed to consolidate declarative memory; however, interactions for non-declarative (HC-independent) memory remain largely uninvestigated. We recently showed that the directional influence in a slow-wave range through a top-down cortical long-range circuit is involved in the consolidation of non-declarative memory. At the synaptic level, the average cortical synaptic strength is known to be potentiated during wakefulness and depressed during sleep. Moreover, learning causes plasticity in a subset of synapses, allocating memory to them. Sleep may help to differentiate synaptic strength between allocated and non-allocated synapses (i.e., improving the signal-to-noise ratio, which may facilitate memory consolidation). Herein, we offer perspectives on inter-areal interactions and synaptic plasticity for memory consolidation during sleep. PMID:29213231

Summary of and factors affecting pesticide concentrations in streams and shallow wells of the lower Susquehanna River basin, Pennsylvania and Maryland, 1993-95

USGS Publications Warehouse

Hainly, Robert A.; Zimmerman, Tammy M.; Loper, Connie A.; Lindsey, Bruce D.

2001-01-01

This report presents the detection frequency of 83 analyzed pesticides, describes the concentrations of those pesticides measured in water from streams and shallow wells, and presents conceptual models of the major factors affecting seasonal and areal patterns of pesticide concentrations in water from streams and shallow wells in the Lower Susquehanna River Basin. Seasonal and areal patterns of pesticide concentrations were observed in 577 samples and nearly 40,000 pesticide analyses collected from 155 stream sites and 169 shallow wells from 1993 to 1995. For this study, shallow wells were defined as those generally less than 200 feet deep.The most commonly detected pesticides were agricultural herbicides?atrazine, metolachlor, simazine, prometon, alachlor, and cyanazine. Atrazine and metolachlor are the two most-used agricultural pesticides in the Lower Susquehanna River Basin. Atrazine was detected in 92 percent of all the samples and in 98 percent of the stream samples. Metolachlor was detected in 83 percent of all the samples and in 95 percent of the stream samples. Nearly half of all the analyzed pesticides were not detected in any sample. Of the 45 pesticides that were detected at least once, the median concentrations of 39 of the pesticides were less than the detection limit for the individual compounds, indicating that for at least 50 percent of the samples collected, those pesticides were not detected. Only 10 (less than 0.025 percent) of the measured concentrations exceeded any established drinking-water standards; 25 concentrations exceeded 2 mg/L (micrograms per liter) and 55 concentrations exceeded 1 mg/L. None of the elevated concentrations were measured in samples collected from streams that are used for public drinking-water supplies, and 8 of the 10 were measured in storm-affected samples.The timing and rate of agricultural pesticide applications affect the seasonal and areal concentration patterns of atrazine, simazine, chlorpyrifos, and diazinon observed in water from wells and streams in the Lower Susquehanna River Basin. Average annual pesticide use for agricultural purposes and nonagricultural pesticide use indicators were used to explain seasonal and areal patterns. Elevated concentrations of some pesticides in streams during base-flow and storm-affected conditions were related to the seasonality of agricultural-use applications and local climate conditions. Agricultural-use patterns affected areal concentration patterns for the high-use pesticides, but indicators of nonagricultural use were needed to explain concentration patterns of pesticides with smaller amounts used for agricultural purposes.Bedrock type influences the movement and discharge of ground water, which in turn affects concentration patterns of pesticides. The ratio of atrazine concentrations in stream base flow to concentrations in shallow wells varied among the different general rock types found in the Lower Susquehanna River Basin. Median concentrations of atrazine in well water and stream base flow tended to be similar in individual areas underlain by carbonate bedrock, indicating the connectivity of water in streams and shallow wells in these areas. In areas underlain by noncarbonate bedrock, median concentrations of atrazine tended to be significantly higher in stream base flow than in well water. This suggests a deep ground-water system that delivers water to shallow wells and a near-surficial system that supplies base-flow water to streams. In addition to the presence or absence of carbonate bedrock, pesticide leaching potential and persistence, soil infiltration capacity, and agricultural land use affected areal patterns in detection frequency and concentration differences between samples collected from streams during base-flow conditions and shallow wells.

Urban biophysical composition and its impact on thermal changes and ecosystem production

NASA Astrophysics Data System (ADS)

Sannigrahi, Srikanta; Rahmat, Shahid; Bhatt, Sandeep

2017-04-01

Human driving forces, especially, urbanization, population pressure, and socioeconomic development are significantly changing the efficiency of ecosystem service provision in an urban ecosystem. Greater Hyderabad Municipal Corporation (GHMC) is the sixth largest urban metropolitan region in India had faced an alarming pace of urban expansion from 1973 to 2015. MODerate Resolution Imaging Spectroradiometer (MODIS) thermal products MOD11A2 and surface reflectance products MOD09A1 were employed in this work to simulate areal and temporal dynamics of Urban Heat Island (UHI) and Diurnal Temperature Range (DTR) of the GHMC region from 2002 to 2015. A Light Use Efficiency (LUE) based Vegetation Photosynthesis Model (VPM) was adopted in this work to quantify Net Primary Production (NPP) and to assess the spatiotemporal changes of NPP during 2002 to 2015. MODIS yearly NPP products MOD17A3 were applied here for the purpose of model validation. Linear Spectral Mixture Analysis (LSMA) technique was employed in this research to generate impervious surface fraction image of GHMC. Spatially explicit gas regulation service included as a regulatory ecosystem service to assess the trade-off between economic viability and ecosystem conservation. Acute urban expansion (over 200%) is mainly accounted to changes the Land Surface Temperature (LST) over 3°C to 4°C in the inner city region during 1991 to 2015. Surface vegetation and moisture dynamics have been evaluated by incorporating Normalized Difference Vegetation Index (NDVI), Normalized Difference Built-up Index (NDBI), Normalized Difference Bareness Index (NDBaI) and Land Surface Water Index (LSWI) for the year of 2002, 2011 and 2015, respectively. The four distinct UHI cluster, i.e. H-H, H-L, L-H & L-L were retrieved from the segmentation of estimated LST using Local Indicators Spatial Autocorrelation (LISA) technique. Further, the Getis-Ord-Gi hotspot analysis method has been employed to identify the local proximity of spatial hot and cold UHI clusters. The areal coverage of built-up urban class was changed from 208.11sq.km in 1973 to 419.55 sq.km in 2015 with 5.03 sq.km/year expansion rate. The selected biophysical indices are found highly sensitive to the changes in land use and land cover (LULC). LST hotspot (H-H) in 2002 was observed in the central and the southeast portion of the region due to the presence of higher thermal anomalies and high concentration of LST (°C). The Island (H-L) part of the city was mostly covered by the built-up urban area in 2002 exhibiting the highest concentration of LST, whereas the mean LST (°C) of the neighboring region is below than the average. GiZScore with low standard deviation value proven the existence of active hotspot of LST and UHI over the central urbanized area in GHMC.A strong negative correlation has found between the selected human driving forces: UHI, LST, population density, settlement density and impervious fraction with NPP ensembles the facts of human control in an urban ecosystem. This study demonstrated the necessity of proper quantification and valuation of urban ecosystem services to achieve effective and efficient decision for urban ecosystem management.

The influence of changes in wind patterns on the areal extension of surface cyanobacterial blooms in a large shallow lake in China.

PubMed

Wu, Tingfeng; Qin, Boqiang; Brookes, Justin D; Shi, Kun; Zhu, Guangwei; Zhu, Mengyuan; Yan, Wenming; Wang, Zhen

2015-06-15

It has been hypothesized that climate change will induce the areal extension of cyanobacterial blooms. However, this hypothesis lacks field-based observation. In the present study both long-term historical data and short-term field measurement were used to identify the importance of changes in wind patterns on the cyanobacterial bloom in Lake Taihu (China), a large, shallow, eutrophic lake located in a subtropical zone. The cyanobacterial bloom mainly composed of Microcystis spp. recurred frequently throughout the year. The regression analysis of multi-year satellite image data extracted by the Floating Algae Index revealed that both the annual mean monthly maximum cyanobacterial bloom area (MMCBA) increased year by year from 2000 to 2011, while the contemporaneous cyanobacterial biomass showed no significant change. However, the correlation analysis shows that MMCBA was negatively correlated with wind speed. Our short-term field measurements indicated that the influence of wind on surface cyanobacterial blooms is that the Chlorophyll-a (Chla) concentration is fully mixing throughout the water column when the wind speed exceed 7 m s(-1). At lower wind speeds, there was vertical stratification of Chla with high surface concentrations and an increase in bloom area. The regression analysis of wind speed indicates that the climate has changed over the last decade. Lake Taihu has become increasingly calm, with the decrease of strong wind frequency between 2000 and 2011, corresponding to the increase in the MMCBA over time. Therefore, we conclude that changes in wind patterns related to climate change have favored the increase of cyanobacterial blooms in Lake Taihu. Copyright © 2015. Published by Elsevier B.V.

Morphology Effect of Vertical Graphene on the High Performance of Supercapacitor Electrode.

PubMed

Zhang, Yu; Zou, Qionghui; Hsu, Hua Shao; Raina, Supil; Xu, Yuxi; Kang, Joyce B; Chen, Jun; Deng, Shaozhi; Xu, Ningsheng; Kang, Weng P

2016-03-23

Graphene and its composites are widely investigated as supercapacitor electrodes due to their large specific surface area. However, the severe aggregation and disordered alignment of graphene sheets hamper the maximum utilization of its surface area. Here we report an optimized structure for supercapacitor electrode, i.e., the vertical graphene sheets, which have a vertical structure and open architecture for ion transport pathway. The effect of morphology and orientation of vertical graphene on the performance of supercapacitor is examined using a combination of model calculation and experimental study. Both results consistently demonstrate that the vertical graphene electrode has a much superior performance than that of lateral graphene electrode. Typically, the areal capacitances of a vertical graphene electrode reach 8.4 mF/cm(2) at scan rate of 100 mV/s; this is about 38% higher than that of a lateral graphene electrode and about 6 times higher than that of graphite paper. To further improve its performance, a MnO2 nanoflake layer is coated on the surface of graphene to provide a high pseudocapacitive contribution to the overall areal capacitance which increases to 500 mF/cm(2) at scan rate of 5 mV/s. The reasons for these significant improvements are studied in detail and are attributed to the fast ion diffusion and enhanced charge storage capacity. The microscopic manipulation of graphene electrode configuration could greatly improve its specific capacitance, and furthermore, boost the energy density of supercapacitor. Our results demonstrate that the vertical graphene electrode is more efficient and practical for the high performance energy storage device with high power and energy densities.

Dust coatings on basaltic rocks and implications for thermal infrared spectroscopy of Mars

USGS Publications Warehouse

Johnson, J. R.; Christensen, P.R.; Lucey, P.G.

2002-01-01

Thin coatings of atmospherically deposited dust can mask the spectral characteristics of underlying surfaces on Mars from the visible to thermal infrared wavelengths, making identification of substrate and coating mineralogy difficult from lander and orbiter spectrometer data. To study the spectral effects of dust coatings, we acquired thermal emission and hemispherical reflectance spectra (5-25 μm; 2000-400 cm-1) of basaltic andesite coated with different thicknesses of air fall-deposited palagonitic soils, fine-grained ceramic clay powders, and terrestrial loess. The results show that thin coatings (10-20 μm) reduce the spectral contrast of the rock substrate substantially, consistent with previous work. This contrast reduction continues linearly with increasing coating thickness until a "saturation thickness" is reached, after which little further change is observed. The saturation thickness of the spectrally flat palagonite coatings is ~100-120 μm, whereas that for coatings with higher spectral contrast is only ~50-75 μm. Spectral differences among coated and uncoated samples correlate with measured coating thicknesses in a quadratic manner, whereas correlations with estimated surface area coverage are better fit by linear functions. Linear mixture modeling of coated samples using the rock substrate and coating materials as end-members is also consistent with their measured coating thicknesses and areal coverage. A comparison of ratios of Thermal Emission Spectrometer (TES) spectra of dark and bright intracrater and windstreak deposits associated with Radau crater suggests that the dark windstreak material may be coated with as much as 90% areal coverage of palagonitic dust. The data presented here also will help improve interpretations of upcoming mini-TES and Thermal Emission Imaging System (THEMIS) observations of coated Mars surface materials.

Satellite monitoring of sea surface pollution

NASA Technical Reports Server (NTRS)

Fielder, G.; Telfer, D. J. (Principal Investigator)

1979-01-01

The author has identified the following significant results. Image processing techniques developed are well adapted to the exploration and isolation of local areas which exhibit small temperature differences between themselves and their surroundings. In the worst case of imagery of small areal extent of sea surface having no coastal boundary in the area, there is yet no method of distinguishing unambiguously an oil spill from fog, cloud, the effect produced by shallow sediments, or the effects of naturally occuring thermal fronts. In the case of uniform slicks of liquid North Sea oil in still air, laboratory simulation experiments show that, for oil thicknesses in excess of 1 or 2 mm, there is, under equilibrium conditions, little dependence of oil surface temperature on the thickness of the oil layer. The surface temperature of oil is consistently higher than that of water, the difference being about 1 K at low values of relative humidity, but tending to increase as the relative humidity increases.

Autonomic dysfunction and osteoporosis after electrical burn.

PubMed

Roshanzamir, Sharareh; Dabbaghmanesh, Mohammad Hossein; Dabbaghmanesh, Alireza; Nejati, Solmaz

2016-05-01

Several studies have shown the importance of the sympathetic nervous system in bone metabolism. There is an evidence of sympathetic skin response (SSR) impairment in electrical burn patients up to 2 years after their injuries. The acute phase of burn is accompanied by increased bone resorption. Whether the prolonged dysfunction of sympathetic nervous system may result in bone metabolism derangement even after the acute phase of electrical burn is the inspiring question for this study. And we tried to find correlation between SSR abnormality and areal bone mineral density (BMD) in electrical burn patients 6 months or more after the incidents. 42 electrical burn patients (≥6 months prior to study) who did not have a known joint or bone disease, history of neuropathy (central or peripheral), diabetes mellitus or consumption of any drug affecting the autonomic nervous system or evidence of neuropathy in nerve conduction study were recruited. We also gathered a control group of 50 healthy subjects (without electrical burn or the exclusion criteria). They went under dual energy X-ray absorptiometry and SSR study. Data were analyzed statistically with SPSS 16.0 making use of independent t-test and Pearson correlation coefficient. P<0.05 was considered significant statistically. Areal BMD was significantly lower in electrical burn patients than control group (P<0.001). SSR latency was significantly prolonged and its amplitude was significantly reduced in burn patients compared to control group (P<0.001). In burn patients there was an inverse correlation of areal BMD of lumbar vertebrae, left femur neck and total femur with SSR latency and a direct correlation of areal BMD with SSR amplitude. In control group there was just direct correlation of areal BMD of lumbar vertebrae and left femur neck with SSR amplitude. Electrical burn patients are at risk of reduced areal BMD long after their injuries. Sympathetic derangement and impaired SSR are correlated with reduction in areal BMD in these patients. Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.

Validation of national land-cover characteristics data for regional water-quality assessment

USGS Publications Warehouse

Zelt, Ronald B.; Brown, Jesslyn F.; Kelley, M.S.

1995-01-01

Land-cover information is used routinely to support the interpretation of water-quality data. The Prototype 1990 Conterminous US Land Cover Characteristics Data Set, developed primarily from Advanced Very High Resolution Radiometer (AVHRR) data, was made available to the US Geological Survey's National Water-Quality Assessment (NAWQA) Program. The study described in this paper explored the utility of the 1990 national data set for developing quantitative estimates of the areal extent of principal land-cover types within large areal units. Land-cover data were collected in 1993 at 210 sites in the Central Nebraska Basins, one of the NAWQA study units. Median percentage-corn estimates for each sampling stratum wre used to produce areally weighted estimates of the percentage-corn cover for hydrologic units. Comparison of those areal estimates with an independent source of 1992 land-cover data showed good agreement. -Authors

A reversible dendrite-free high-areal-capacity lithium metal electrode

PubMed Central

Wang, Hui; Matsui, Masaki; Kuwata, Hiroko; Sonoki, Hidetoshi; Matsuda, Yasuaki; Shang, Xuefu; Takeda, Yasuo; Yamamoto, Osamu; Imanishi, Nobuyuki

2017-01-01

Reversible dendrite-free low-areal-capacity lithium metal electrodes have recently been revived, because of their pivotal role in developing beyond lithium ion batteries. However, there have been no reports of reversible dendrite-free high-areal-capacity lithium metal electrodes. Here we report on a strategy to realize unprecedented stable cycling of lithium electrodeposition/stripping with a highly desirable areal-capacity (12 mAh cm−2) and exceptional Coulombic efficiency (>99.98%) at high current densities (>5 mA cm−2) and ambient temperature using a diluted solvate ionic liquid. The essence of this strategy, that can drastically improve lithium electrodeposition kinetics by cyclic voltammetry premodulation, lies in the tailoring of the top solid-electrolyte interphase layer in a diluted solvate ionic liquid to facilitate a two-dimensional growth mode. We anticipate that this discovery could pave the way for developing reversible dendrite-free metal anodes for sustainable battery chemistries. PMID:28440299

Surface assessment and modification of concrete using abrasive blasting

NASA Astrophysics Data System (ADS)

Millman, Lauren R.

Composite systems are applied to concrete substrates to strengthen and extend the service life. Successful restoration or rehabilitation requires surface preparation prior to the application of the overlay. Surface coatings, waterproofing systems, and other external surface applications also require surface preparation prior to application. Abrasive blast media is often used to clean and uniformly roughen the substrate. The appropriate surface roughness is necessary to facilitate a strong bond between the existing substrate and overlay. Thus, surface modification using abrasive blast media (sand and dry ice), their respective environmental effects, surface roughness characterization prior to and after blasting, and the adhesion between the substrate and overlay are the focus of this dissertation. This dissertation is comprised of an introduction, a literature review, and four chapters, the first of which addresses the environmental effects due to abrasive blasting using sand, water, and dry ice. The assessment considered four response variables: carbon dioxide (CO2) emissions, fuel and energy consumption, and project duration. The results indicated that for sand blasting and water jetting, the primary factor contributing to environmental detriment was CO22 emissions from vehicular traffic near the construction site. The second chapter is an analysis of the International Concrete Repair Institute's (ICRI) concrete surface profiles (CSPs) using 3-D optical profilometry. The primary objective was to evaluate the suitability of approximating the 3-D surface (areal) parameters with those extracted from 2-D (linear) profiles. Four profile directions were considered: two diagonals, and lines parallel and transverse to the longitudinal direction of the mold. For any CSP mold, the estimation of the 3-D surface roughness using a 2-D linear profile resulted in underestimation and overestimation errors exceeding 50%, demonstrating the inadequacy of 2-D linear profiles to approximate the 3-D concrete surface profiles. The errors were reduced when a weighted average of the four linear profiles approximated the corresponding 3-D parameter. The following chapter considers the parametric and sensitivity of concrete surface topography measurements. The weighted average of the four 2-D profiles consistently resulted in underestimation of the corresponding 3-D parameters: the dispersion of surface elevations (Sq) and the roughness (Sa). Results indicated the 3-D parameter, Sq, had the least sensitivity to data point reduction. The final chapter investigated surface modification using dry ice and sand blasting. The overall objective was to evaluate the change in the 3-D surface roughness (Sa) following blasting as functions of mix design and as induced by freeze-thaw cycling, and to compare the results obtained using dry ice with those obtained using sand as the blasting media. In general, sand blasting produced larger changes in Sa compared to dry ice blasting for the concrete mix designs considered. The primary mechanism responsible for altering the surface topography of the concrete was the scaling of the superficial cement paste layer on the exposed surface, which was due to freeze-thaw cycling. The largest relative change in roughness following blasting occurred in the control samples, which had not undergone freeze-thaw cycling.

Solid-state supercapacitors with ionic liquid gel polymer electrolyte based on poly (3, 4-ethylenedioxythiophene), carbon nanotubes, and metal oxides nanocomposites for electrical energy storage

NASA Astrophysics Data System (ADS)

Obeidat, Amr M.

Clean and renewable energy systems have emerged as an important area of research having diverse and significant new applications. These systems utilize different energy storage methods such as the batteries and supercapacitors. Supercapacitors are electrochemical energy storage devices that are designed to bridge the gap between batteries and conventional capacitors. Supercapacitors which store electrical energy by electrical double layer capacitance are based on large surface area structured carbons. The materials systems in which the Faradaic reversible redox reactions store electrical energy are the transition metal oxides and electronically conducting polymers. Among the different types of conducting polymers, poly (3, 4- ethylenedioxythiophene) (PEDOT) is extensively investigated owing to its chemical and mechanical stability. Due to instability of aqueous electrolytes at high voltages and toxicity of organic electrolytes, potential of supercapacitors has not been fully exploited. A novel aspect of this work is in utilizing the ionic liquid gel polymer electrolyte to design solid-state supercapacitors for energy storage. Various electrochemical systems were investigated including graphene, PEDOT, PEDOT-carbon nanotubes, PEDOT-manganese oxide, and PEDOT-iron oxide nanocomposites. The electrochemical performance of solid-state supercapacitor devices was evaluated based on cyclic voltammetry (CV), charge-discharge (CD), prolonged cyclic tests, and electrochemical impedance spectroscopy (EIS) techniques. Raman spectroscopy technique was also utilized to analyze the bonding structure of the electrode materials. The graphene solid-state supercapacitor system displayed areal capacitance density of 141.83 mF cm-2 based on high potential window up to 4V. The PEDOT solid-state supercapacitor system was synthesized in acetonitrile and aqueous mediums achieving areal capacitance density of 219.17 mF cm-2. The hybrid structure of solid-state supercapacitors was also studied in solid-state design based on PEDOT and graphene electrodes that produced areal capacitance density of 198.26 mF cm-2. Symmetrical PEDOT-manganese oxide nanocomposites were synthesized by co-deposition and dip-coating techniques to fabricate solid-state supercapacitor systems achieving areal capacitance density of 122.08 mF cm-2 credited to the PEDOT-MnO2 supercapacitor that was synthesized by dipping the PEDOT electrode in pure KMnO4 solution. The electrochemical performance of PEDOT-carbon nanotube solid-state supercapacitors was also investigated in both acetonitrile and aqueous medium showing good dispersion characteristics with optimum CNT content of 1 mg. The PEDOT-CNT solid-state supercapacitor system synthesized in acetonitrile displayed areal capacitance density of 297.43 mF cm-2. PEDOT-Fe2O3 nanocomposites were synthesized by single-step co-deposition techniques, and these were used to fabricate solid-state supercapacitors achieving areal capacitance density of 96.89 mF cm-2. Furthermore, some of these thin flexible solid-state supercapacitors were integrated with solar cells for direct storage of solar electricity, which proved to be promising as autonomous power source for flexible and wearable electronics. This dissertation describes the electrode synthesis, design and properties of solid-state supercapacitors, and their electrochemical performance in the storage of electrical energy.

Results of the application of seismic-reflection and electromagnetic techniques for near-surface hydrogeologic and environmental investigations at Fort Bragg, North Carolina

USGS Publications Warehouse

Meyer, M.T.; Fine, J.M.

1997-01-01

As part of the U.S. Geological Survey's Resource Conservation and Recovery Act, Facilities Investigations at Fort Bragg, North Carolina, selected geophysical techniques were evaluated for their usefulness as assessment tools for determining subsurface geology, delineating the areal extent of potentially contaminated landfill sites, and locating buried objects and debris of potential environmental concern. Two shallow seismic-reflection techniques (compression and shear wave) and two electromagnetic techniques (ground-penetrating radar and terrain conductivity) were evaluated at several sites at the U.S. Army Base. The electromagnetic techniques also were tested for tolerance to cultural noise, such as nearby fences, vehicles, and power lines. For the terrain conductivity tests, two instruments were used--the EM31 and EM34, which have variable depths of exploration. The shallowest reflection event was 70 feet below land surface observed in common-depth point, stacked compression-wave data from 24- and 12-fold shallow-seismic-reflection surveys. Several reflection events consistent with clay-sand interfaces between 70 and 120 feet below land surface, along with basement-saprolite surfaces, were imaged in the 24-fold, common- depth-point stacked data. 12-fold, common-depth-point stacked data set contained considerably more noise than the 24-fold, common-depth-point data, due to reduced shot-to-receiver redundancy. Coherent stacked reflection events were not observed in the 24-fold, common-depth-point stacked shear-wave data because of the partial decoupling of the shear- wave generator from the ground. At one site, ground-penetrating radar effectively delineated a shallow, 2- to 5-foot thick sand unit bounded by thin (less than 1 foot) clay layers. The radar signal was completely attenuated where the overlying and underlying clay units thickened and the sand unit thinned. The pene- tration depth of the radar signal was less than 10 feet below land surface. A slight increase in electromagnetic conductivity across shallow sampling EM31 and EM34 profiles provided corroborative evidence of the shallow, thickening clay units. Plots of raw EM31 and EM34 data provided no direct interpretable information to delineate sand and clay units in the shallow subsurface. At two sites, the ground-penetrating radar effectively delineated the lateral continuity of surficial sand units 5 to 25 feet in thickness and the tops of their underlying clay units. The effective exploration depth of the ground-penetrating radar was limited by the proximity of clay units to the subsurface and their thickness. The ground-penetrating radar delineated the areal extent and depth of cover at a previously unrecognized extension of a trench-like landfill underlying a vehicle salvage yard. Attenuation of the radar signal beneath the landfill cover and the adjacent subsurface clays made these two mediums indistinguishable by ground-penetrating radar; however, EM31 data indicated that the electrical conductivity of the landfill was higher than the subsurface material adjacent to the landfill. The EM31 and EM34 conductivity surveys defined the areal extent of a landfill whose boundaries were inaccurately mapped, and also identified the locations of an old dumpsite and waste incinerator site at another landfill. A follow-up ground-penetrating radar survey of the abandoned dumpsite showed incongruities in some of the shallow radar reflections interpreted as buried refuse dispersed throughout the landfill. The ground-penetrating radar and EM31 effectively delineated a shallow buried fuel-oil tank. Of the three electromagnetic instruments, the ground-penetrating radar with the shielded 100-megahertz antenna was the least affected by cultural noise followed, in order, by the EM31 and EM34. The combination of terrain- conductivity and ground-penetrating radar for the site assessment of the landfill provided a powerful means to identify the areal extent of the landfill, potenti

Riparian vegetation and its water use during 1995 along the Mojave River, Southern California

USGS Publications Warehouse

Lines, Gregory C.; Bilhorn, Thomas W.

1996-01-01

The extent and areal density of riparian vegetation, including both phreatophytes and hydrophytes, were mapped along the 100-mile main stem of the Mojave River during 1995. Mapping was aided by vertical false-color infrared and low-level oblique photographs. However, positive identification of plant species and plant physiological stress required field examination. The consumptive use of ground water and surface water by different areal densities of riparian plant communities along the main stem of the Mojave River was estimated using water-use data from a select group of studies in the southwestern United States. In the Alto subarea of the Mojave basin management area, consumptive water use during 1995 by riparian vegetation was estimated to be about 5,000 acre-feet upstream from the Lower Narrows and about 6,000 acre-feet downstream in the transition zone. In the Centro and Baja subareas, consumptive water use was estimated to be about 3,000 acre-feet and 2,000 acre-feet, respectively, during 1995. Consumptive water use by riparian vegetation in the Afton area, downstream from the Baja subarea, was estimated to be about 600 acre-feet during 1995. Consumptive water use by riparian vegetation during 1995 is considered representative of "normal" hydrologic conditions along the Mojave River. Barring major changes in the areal extent and density of riparian vegetation, the 1995 consumptive-use estimates should be fairly representative of riparian vegetation water use during most years. Annual consumptive use, however, could vary from the 1995 estimates as much as plus or minus 50 percent because of extreme hydrologic conditions (periods of high water table following extraordinarily large runoff in the Mojave River or periods of extended drought).

The Effect of Environmental Conditions on Tropical Deep Convective Systems Observed from the TRMM Satellite

NASA Technical Reports Server (NTRS)

Lin, Bing; Wielicki, Bruce A.; Minnis, Patrick; Chambers, Lin H.; Xu, Kuan-Man; Hu, Yongxiang; Fan, Tai-Fang

2005-01-01

This study uses measurements of radiation and cloud properties taken between January and August 1998 by three Tropical Rainfall Measuring Mission (TRMM) instruments, the Clouds and the Earth's Radiant Energy System (CERES) scanner, the TRMM Microwave Imager (TMI), and the Visible and InfraRed Scanner (VIRS), to evaluate the variations of tropical deep convective systems (DCS) with sea surface temperature (SST) and precipitation. This study finds that DCS precipitation efficiency increases with SST at a rate of approx. 2%/K. Despite increasing rainfall efficiency, the cloud areal coverage rises with SST at a rate of about 7%/K in the warm tropical seas. There, the boundary layer moisture supply for deep convection and the moisture transported to the upper troposphere for cirrus-anvil cloud formation increase by approx. 6.3%/K and approx. 4.0%/K, respectively. The changes in cloud formation efficiency, along with the increased transport of moisture available for cloud formation, likely contribute to the large rate of increasing DCS areal coverage. Although no direct observations are available, the increase of cloud formation efficiency with rising SST is deduced indirectly from measurements of changes in the ratio of DCS ice water path and boundary layer water vapor amount with SST. Besides the cloud areal coverage, DCS cluster effective sizes also increase with precipitation. Furthermore, other cloud properties, such as cloud total water and ice water paths, increase with SST. These changes in DCS properties will produce a negative radiative feedback for the earth's climate system due to strong reflection of shortwave radiation by the DCS. These results significantly differ from some previous hypothesized dehydration scenarios for warmer climates, and have great potential in testing current cloud-system resolving models and convective parameterizations of general circulation models.

Decontamination of Surfaces Exposed to Carbonbased Nanotubes and Nanomaterials

NASA Astrophysics Data System (ADS)

Karimi, Zahra

Contamination of surfaces by nanomaterials can happen due to accidental spillage and release or gradual accumulation during processing or handling. Considering the increasingly wide use of nanomaterials in industry and research labs and also taking into account the diversity of physical and chemical properties of different nanomaterials (such as solubility, aggregation/agglomeration, and surface reactivity), there is a pressing need to define reliable nanomaterial-specific decontamination guidelines. In this project, we propose and investigate a potential method for surface decontamination of carbon-based nanomaterials using solvent cleaning and wipes. The results show that the surfactant-assisted removal efficiencies of multi-walled carbon nanotubes, single walled carbon nantubes and single walled carbon nano-horns from silicon wafers through wiping is greater than 95%, 90% and 78%, respectively. The need for further studies to understand the mechanisms of nanomaterial removal from surfaces and development of standard techniques for surface decontamination of nanomaterials is highlighted. Another phase of experiments were performed to examine the efficiency of surfactants to remove multi-walled carbon nanotubes (MWCNTs) from silicon substrates with nano and microscaled features. In the first set of experiments, nanoscale features were induced on silicon wafers using SF6 and O2 plasma. Atomic force microscopy (AFM) was used to observe the surface topology and roughness. In the second set, well-defined microscale topological features were induced on silicon wafers using photo lithography and plasma etching. The etching time was varied to create semi-ellipsoidal pits with average diameter and height of ~ 7-9 microm, and ~ 1-3 microm, respectively. MWCNTs in the form of liquid solution were deposited on the surface of silicon wafers using the spin coating process. For the cleaning process, the contaminated surfaces were first sprayed with different types of surfactant or water. Then, the MWCNTs were wiped off using a simple wiping mechanism. The areal density of the MWCNTs was quantified prior to and after the removal using scanning electron microscopy (SEM) and post-image processing. For a surface featured with nanoscale asperities, the removal efficiency was measured to be in the range 83-99% based on substrate type and surface roughness. No evident relationship was observed between the etching time and the removal efficiency. For microscale features, increase of the etching time significantly decreases the removal efficiency.

CO2-efflux measurements for evaluating source zone natural attenuation rates in a petroleum hydrocarbon contaminated aquifer.

PubMed

Sihota, Natasha J; Singurindy, Olga; Mayer, K Ulrich

2011-01-15

In order to gain regulatory approval for source zone natural attenuation (SZNA) at hydrocarbon-contaminated sites, knowledge regarding the extent of the contamination, its tendency to spread, and its longevity is required. However, reliable quantification of biodegradation rates, an important component of SZNA, remains a challenge. If the rate of CO(2) gas generation associated with contaminant degradation can be determined, it may be used as a proxy for the overall rate of subsurface biodegradation. Here, the CO(2)-efflux at the ground surface is measured using a dynamic closed chamber (DCC) method to evaluate whether this technique can be used to assess the areal extent of the contaminant source zone and the depth-integrated rate of contaminant mineralization. To this end, a field test was conducted at the Bemidji, MN, crude oil spill site. Results indicate that at the Bemidji site the CO(2)-efflux method is able to both delineate the source zone and distinguish between the rates of natural soil respiration and contaminant mineralization. The average CO(2)-efflux associated with contaminant degradation in the source zone is estimated at 2.6 μmol m(-2) s(-1), corresponding to a total petroleum hydrocarbon mineralization rate (expressed as C(10)H(22)) of 3.3 g m(-2) day(-1).

ON THE STAR FORMATION LAW FOR SPIRAL AND IRREGULAR GALAXIES

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

Elmegreen, Bruce G., E-mail: bge@us.ibm.com

2015-12-01

A dynamical model for star formation on a galactic scale is proposed in which the interstellar medium is constantly condensing to star-forming clouds on the dynamical time of the average midplane density, and the clouds are constantly being disrupted on the dynamical timescale appropriate for their higher density. In this model, the areal star formation rate scales with the 1.5 power of the total gas column density throughout the main regions of spiral galaxies, and with a steeper power, 2, in the far outer regions and in dwarf irregular galaxies because of the flaring disks. At the same time, theremore » is a molecular star formation law that is linear in the main and outer parts of disks and in dIrrs because the duration of individual structures in the molecular phase is also the dynamical timescale, canceling the additional 0.5 power of surface density. The total gas consumption time scales directly with the midplane dynamical time, quenching star formation in the inner regions if there is no accretion, and sustaining star formation for ∼100 Gyr or more in the outer regions with no qualitative change in gas stability or molecular cloud properties. The ULIRG track follows from high densities in galaxy collisions.« less

Hypolimnetic dissolved-oxygen dynamics within selected White River reservoirs, northern Arkansas-southern Missouri, 1974-2008

USGS Publications Warehouse

De Lanois, Jeanne L.; Green, W. Reed

2011-01-01

Dissolved oxygen is a critical constituent in reservoirs and lakes because it is essential for metabolism by all aerobic aquatic organisms. In general, hypolimnetic temperature and dissolved-oxygen concentrations vary from summer to summer in reservoirs, more so than in natural lakes, largely in response to the magnitude of flow into and release out of the water body. Because eutrophication is often defined as the acceleration of biological productivity resulting from increased nutrient and organic loading, hypolimnetic oxygen consumption rates or deficits often provide a useful tool in analyzing temporal changes in water quality. This report updates a previous report that evaluated hypolimnetic dissolved-oxygen dynamics for a 21-year record (1974-94) in Beaver, Table Rock, Bull Shoals, and Norfork Lakes, as well as analyzed the record for Greers Ferry Lake. Beginning in 1974, vertical profiles of temperature and dissolved-oxygen concentrations generally were collected monthly from March through December at sites near the dam of each reservoir. The rate of change in the amount of dissolved oxygen present below a given depth at the beginning and end of the thermal stratification period is referred to as the areal hypolimnetic oxygen deficit. Areal hypolimnetic oxygen deficit was normalized for each reservoir based on seasonal flushing rate between April 15 and October 31 to adjust for wet year and dry year variability. Annual cycles in thermal stratification within Beaver, Table Rock, Bull Shoals, Norfork, and Greers Ferry Lakes exhibited typical monomictic (one extended turnover period per year) characteristics. Flow dynamics drive reservoir processes and need to be considered when analyzing areal hypolimnetic oxygen deficit rates. A nonparametric, locally weighted scatter plot smooth line describes the relation between areal hypolimnetic oxygen deficit and seasonal flushing rates, without assuming linearity or normality of the residuals. The results in this report are consistent with earlier findings that oxygen deficit rates and flushing-rate adjusted areal hypolimnetic oxygen deficit in Beaver and Table Rock Lakes were decreasing between 1974 and 1994. The additional data (1995-2008) demonstrate that the decline in flushing-rate adjusted areal hypolimnetic oxygen deficit in Beaver Lake has continued, whereas that in Table Rock Lake has flattened out in recent years. The additional data demonstrate the flushing-rate adjusted areal hypolimnetic oxygen deficit in Bull Shoals and Norfork Lakes have declined since 1995 (improved water quality), which was not indicated in earlier studies, while Greers Ferry Lake showed little net change over the period of record. Given the amount of data (35 years) for these reservoirs, developing an equation or model to predict areal hypolimnetic oxygen deficit and, therefore, areal hypolimnetic oxygen content, on any given day during future stratification seasons may be useful for reservoir managers.

Cassini/VIMS observes rough surfaces on Titan's Punga Mare in specular reflection.

PubMed

Barnes, Jason W; Sotin, Christophe; Soderblom, Jason M; Brown, Robert H; Hayes, Alexander G; Donelan, Mark; Rodriguez, Sebastien; Mouélic, Stéphane Le; Baines, Kevin H; McCord, Thomas B

Cassini /VIMS high-phase specular observations of Titan's north pole during the T85 flyby show evidence for isolated patches of rough liquid surface within the boundaries of the sea Punga Mare. The roughness shows typical slopes of 6°±1°. These rough areas could be either wet mudflats or a wavy sea. Because of their large areal extent, patchy geographic distribution, and uniform appearance at low phase, we prefer a waves interpretation. Applying theoretical wave calculations based on Titan conditions our slope determination allows us to infer winds of 0.76±0.09 m/s and significant wave heights of [Formula: see text] cm at the time and locations of the observation. If correct, these would represent the first waves seen on Titan's seas, and also the first extraterrestrial sea-surface waves in general.

Food Irradiation Using Electron Beams and X-Rays

NASA Astrophysics Data System (ADS)

Miller, Bruce

2003-04-01

In this presentation we will discuss the technology of food irradiation using electron accelerators. Food irradiation has generally come to describe the use of ionizing radiation to decrease the population of, or prevent the growth of, undesirable biological organisms in food. The many beneficial applications include insect disinfestation, sprouting inhibition, delayed ripening, and the enhanced safety and sterilization of fresh and frozen meat products, seafood, and eggs. With special regard to food safety, bacteria such as Salmonella enteridis, Listeria monocytogenes, Campylobacter jejuni and Escherichia coli serotype O157:H7 are the primary causes of food poisoning in industrialized countries. Ionizing doses in the range of only 1-5 kilogray (kGy) can virtually eliminate these organisms from food, without affecting the food's sensory and nutritional qualities, and without inducing radioactivity. The key elements of an accelerator-based irradiation facility include the accelerator system, a scanning system, and a material handling system that moves the product through the beam in a precisely controlled manner. Extensive radiation shielding is necessary to reduce the external dose to acceptable levels, and a safety system is necessary to prevent accidental exposure of personnel during accelerator operation. Parameters that affect the dose distribution must be continuously monitored and controlled with process control software. The choice of electron beam vs x-ray depends on the areal density (density times thickness) of the product and the anticipated mass throughput. To eliminate nuclear activation concerns, the maximum kinetic energy of the accelerator is limited by regulation to 10 MeV for electron beams, and 5 MeV for x-rays. From penetration considerations, the largest areal density that can be treated by double-sided electron irradiation at 10 MeV is about 8.8 g/cm2. Products having greater areal densities must be processed using more penetrating x-rays. The mass throughput (dM/dt in kg/s) of an accelerator-based system is proportional to the average beam power (P in kW), and inversely proportional to the minimum required dose (Dm in kGy, with 1 kGy = 1 kJ/kg). The constant of proportionality is the mass throughput efficiency. Throughput efficiencies of 0.4 or better are typical of electron beam installations, but are only 0.025-0.035 for x-ray installations, primarily because of the inefficiency of bremsstrahlung generation at 5 MeV (about 8an axially-coupled, standing-wave, L-band linac with an average power in excess of 100 kW to achieve reasonable throughput rates with x-ray processing. Various design aspects of this new machine will be presented.

Effects of morphology parameters on anti-icing performance in superhydrophobic surfaces

NASA Astrophysics Data System (ADS)

Nguyen, Thanh-Binh; Park, Seungchul; Lim, Hyuneui

2018-03-01

In this paper, we report the contributions of actual ice-substrate contact area and nanopillar height to passive anti-icing performance in terms of adhesion force and freezing time. Well-textured nanopillars with various parameters were fabricated via colloidal lithography and a dry etching process. The nanostructured quartz surface was coated with low-energy material to confer water-repellent properties. These superhydrophobic surfaces were investigated to determine the parameters essential for reducing adhesion strength and delaying freezing time. A well-textured surface with nanopillars of very small top diameter, regardless of height, could reduce adhesion force and delay freezing time in a subsequent de-icing process. Small top diameters of nanopillars also ensured the metastable Cassie-Baxter state based on energy barrier calculations. The results demonstrated the important role of areal fraction in anti-icing efficiency, and the negligible contribution of texture height. This insight into icing phenomena should lead to design of improved ice-phobic surfaces in the future.

Does The Earth Have an Adaptive Infrared Iris?

NASA Technical Reports Server (NTRS)

Lindzen, Richard S.; Chou, Ming-Dah; Hou, Arthur

2000-01-01

Observations and analyses of water vapor and clouds in the tropics over the past decade suggest a different approach to radiative climate feedbacks: namely, that high clouds and high free-tropospheric relative humidity are largely tied to each other, and that the main feedback consists in changing the relative areas of cloudy/moist regions vis a vis clear/dry regions in response to the surface temperature of the cloudy/moist regions - as opposed to altering the humidity in either of the regions. This is an intrinsically 2-dimensional (horizontal and vertical) effect which does not readily enter simple 1-dimensional (vertical) radiative-convective schemes which emphasize average humidity, etc. Preliminary analyses of cloud data for the eastern part of the Western Pacific from the Japanese GMS-5(Geostationary Meteorological Satellite), are supportive of this suggestion - pointing to a 15% reduction in cloudy/moist area for a 1C increase of the sea surface temperature as measured by the cloud-weighted SST (sea surface temperature). The implication of this result is examined using a simple 2-dimensional radiative-convective model. The calculations show that such a change in the tropics would lead to a strong negative feedback in the global climate, with a feedback factor of about -1.7, which, if correct, would easily dominate the positive water vapor feedback found in current models. This new feedback mechanism, in effect, constitutes an adaptive infrared iris that opens and closes in order to control the OLR (outgoing longwave radiation) in response to changes in surface temperature in a manner similar to the way in which an eye's iris opens and closes in response to changing light levels. The climate sensitivity resulting from this thermostatic mechanism is consistent with the independent determination by Lindzen and Giannitisis (1998). Preliminary attempts to replicate observations with GCMs (General Circulation Models) suggest that models lack such a negative cloud/moist areal feedback.

Diagnosing land management and climate change impacts on snowmelt in semi-arid agricultural cold regions with an improved snowmelt model

NASA Astrophysics Data System (ADS)

Harder, P.; Pomeroy, J. W.; Helgason, W.

2017-12-01

Spring snowmelt is the most important hydrological event in semi-arid agricultural cold regions, recharging soil moisture and generating the majority of annual runoff. Adoption of no-till agricultural practices means vast areas of the Canadian Prairies, and other analogous regions, are characterized by standing crop stubble. The emergence of stubble during snowmelt will have important implications for the snowpack energy balance. In addition, spatiotemporally dynamic snowcover heterogeneity leads to enhancement of turbulent flux contributions to melt by advection of energy from warm moist bare ground to snow. Stubble emergence and advection are generally unaccounted for in snow models. To address these challenges a stubble-snow-atmosphere surface energy balance model is developed that relates stubble parameters to the snow surface energy balance. Existing fractal understandings of snowcover geometry are applied to a conceptualized boundary layer integration model to estimate a sensible and latent heat advection efficiency. The small-scale nature of stubble-snow-atmosphere interactions makes direct validation of the energy balance terms challenging. However, the energy balance estimates are assessed by comparing to measured snow and stubble surface temperatures, snow surface incoming shortwave radiation and areal average turbulent fluxes. Advection estimates are validated from a two-dimensional air temperature, water vapor and windspeed profiles. Snowcover geometry relationships are validated/updated with unmanned air vehicle observations. Observations for model assessment occurred in 2015 and 2016 on wheat and canola stubble fields in north-central Saskatchewan, Canada. The model is not calibrated to melt rates, yet compares well with available observations, providing confidence in the model structure and parameterization. Sensitivity analysis using the model revealed compensatory relationships in energy balance terms resulting in limited reduction of energy available for snowmelt as stubble height increases. The proposed model is used to diagnose the influence of stubble management and climate change on melt processes to reveal the potential implications on runoff generation, infiltration and land-atmosphere interactions.

Associations of all-cause mortality with census-based neighbourhood deprivation and population density in Japan: a multilevel survival analysis.

PubMed

Nakaya, Tomoki; Honjo, Kaori; Hanibuchi, Tomoya; Ikeda, Ai; Iso, Hiroyasu; Inoue, Manami; Sawada, Norie; Tsugane, Shoichiro

2014-01-01

Despite evidence that neighbourhood conditions affect residents' health, no prospective studies of the association between neighbourhood socio-demographic factors and all-cause mortality have been conducted in non-Western societies. Thus, we examined the effects of areal deprivation and population density on all-cause mortality in Japan. We employed census and survival data from the Japan Public Health Center-based Prospective Study, Cohort I (n = 37,455), consisting of middle-aged residents (40 to 59 years at the baseline in 1990) living in four public health centre districts. Data spanned between 1990 and 2010. A multilevel parametric proportional-hazard regression model was applied to estimate the hazard ratios (HRs) of all-cause mortality by two census-based areal variables--areal deprivation index and population density--as well as individualistic variables such as socioeconomic status and various risk factors. We found that areal deprivation and population density had moderate associations with all-cause mortality at the neighbourhood level based on the survival data with 21 years of follow-ups. Even when controlling for individualistic socio-economic status and behavioural factors, the HRs of the two areal factors (using quartile categorical variables) significantly predicted mortality. Further, this analysis indicated an interaction effect of the two factors: areal deprivation prominently affects the health of residents in neighbourhoods with high population density. We confirmed that neighbourhood socio-demographic factors are significant predictors of all-cause death in Japanese non-metropolitan settings. Although further study is needed to clarify the cause-effect relationship of this association, the present findings suggest that health promotion policies should consider health disparities between neighbourhoods and possibly direct interventions towards reducing mortality in densely populated and highly deprived neighbourhoods.

Associations of All-Cause Mortality with Census-Based Neighbourhood Deprivation and Population Density in Japan: A Multilevel Survival Analysis

PubMed Central

Nakaya, Tomoki; Honjo, Kaori; Hanibuchi, Tomoya; Ikeda, Ai; Iso, Hiroyasu; Inoue, Manami; Sawada, Norie; Tsugane, Shoichiro

2014-01-01

Background Despite evidence that neighbourhood conditions affect residents' health, no prospective studies of the association between neighbourhood socio-demographic factors and all-cause mortality have been conducted in non-Western societies. Thus, we examined the effects of areal deprivation and population density on all-cause mortality in Japan. Methods We employed census and survival data from the Japan Public Health Center-based Prospective Study, Cohort I (n = 37,455), consisting of middle-aged residents (40 to 59 years at the baseline in 1990) living in four public health centre districts. Data spanned between 1990 and 2010. A multilevel parametric proportional-hazard regression model was applied to estimate the hazard ratios (HRs) of all-cause mortality by two census-based areal variables —areal deprivation index and population density—as well as individualistic variables such as socioeconomic status and various risk factors. Results We found that areal deprivation and population density had moderate associations with all-cause mortality at the neighbourhood level based on the survival data with 21 years of follow-ups. Even when controlling for individualistic socio-economic status and behavioural factors, the HRs of the two areal factors (using quartile categorical variables) significantly predicted mortality. Further, this analysis indicated an interaction effect of the two factors: areal deprivation prominently affects the health of residents in neighbourhoods with high population density. Conclusions We confirmed that neighbourhood socio-demographic factors are significant predictors of all-cause death in Japanese non-metropolitan settings. Although further study is needed to clarify the cause-effect relationship of this association, the present findings suggest that health promotion policies should consider health disparities between neighbourhoods and possibly direct interventions towards reducing mortality in densely populated and highly deprived neighbourhoods. PMID:24905731

Flexible all solid-state supercapacitors based on chemical vapor deposition derived graphene fibers.

PubMed

Li, Xinming; Zhao, Tianshuo; Chen, Qiao; Li, Peixu; Wang, Kunlin; Zhong, Minlin; Wei, Jinquan; Wu, Dehai; Wei, Bingqing; Zhu, Hongwei

2013-11-07

Flexible all-solid-state supercapacitors based on graphene fibers are demonstrated in this study. Surface-deposited oxide nanoparticles are used as pseudo-capacitor electrodes to achieve high capacitance. This supercapacitor electrode has an areal capacitance of 42 mF cm(-2), which is comparable to the capacitance for fiber-based supercapacitors reported to date. During the bending and cycling of the fiber-based supercapacitor, the stability could be maintained without sacrificing the electrochemical performance, which provides a novel and simple way to develop flexible, lightweight and efficient graphene-based devices.

Improving alpine-region spectral unmixing with optimal-fit snow endmembers

NASA Technical Reports Server (NTRS)

Painter, Thomas H.; Roberts, Dar A.; Green, Robert O.; Dozier, Jeff

1995-01-01

Surface albedo and snow-covered-area (SCA) are crucial inputs to the hydrologic and climatologic modeling of alpine and seasonally snow-covered areas. Because the spectral albedo and thermal regime of pure snow depend on grain size, areal distribution of snow grain size is required. Remote sensing has been shown to be an effective (and necessary) means of deriving maps of grain size distribution and snow-covered-area. Developed here is a technique whereby maps of grain size distribution improve estimates of SCA from spectral mixture analysis with AVIRIS data.

Alaskan Permafrost Analogs of Martian Small Valley Networks, Thermokarst, Terrain Softening, Terraces, and Volcanic Craters

NASA Technical Reports Server (NTRS)

Kargel, Jeffrey S.; Wessels, Rick; Beget, James E.; Eddy, Thomas; Lloyd, Sandra; Macaulay, Don; Proch, Mark; Skinner, Jim; Tanaka, Kenneth L.

2004-01-01

A geomorphic landscape analog in the Bering Land Bridge National Preserve (Alaska) offers a model for Mars where (1) fluvial and alluvial deposition, volcanism, and other processes first produced a layered ice-rich upper crust, and then (2) severe permafrost conditions (mild by today's Martian standards) and heterogeneous heat flow and volcanism have modified this terrain to produce a geomorphic areal mosaic that is alternately dominated by (a) geothermal meltwater and sublimation (bottom-up heat flow) and (b) surface-driven meltwater and sublimation (top-down heat flow).

The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Geologic map analyses: Correlation of geologic and cratering histories. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Leake, M. A.

1982-01-01

Geologic map analyses are expanded, beginning with a discussion of particular regions which may illustrate volcanic and ballistic plains emplacement on Mercury. Major attention is focused on the surface history of Mercury through discussion of the areal distribution of plains and craters and the paleogeologic maps of the first quadrant. A summary of the lunar intercrater plains formation similarly interrelates the information from the Moon's geologic and cratering histories.

A New Spin on an Old Technology: Piezoelectric Ejecta Diagnostics for Shock Environments

NASA Astrophysics Data System (ADS)

Vogan, W. S.; Anderson, W. W.; Grover, M.; King, N. S. P.; Lamoreaux, S. K.; Morley, K. B.; Rigg, P. A.; Stevens, G. D.; Turley, W. D.; Buttler, W. T.

2006-07-01

In our investigation of ejecta, or metal particulate emitted from a surface subjected to shock-loaded conditions, we have developed a shock experiment suitable for testing new ideas in piezoelectric mass and impact detectors. High-explosive (HE) shock loading of tin targets subjected to various machined and compressed finishes results in significant trends in ejecta characteristics of interest such as areal density and velocity. Our enhanced piezoelectric diagnostic, "piezo-pins" modified for shock mitigation, have proven levels of robustness and reliability suitable for effective operation in these ejecta milieux. These field tests address questions about ejecta production from surfaces of interest; experimental results are discussed and compared with those from complementary diagnostics such as x-ray and optical attenuation visualization techniques.

Radiation Climatology of the Greenland Ice Sheet Derived from Greenland Climate Network Data

NASA Technical Reports Server (NTRS)

Steffen, Konrad; Box, Jason

2003-01-01

The magnitude of shortwave and longwave dative fluxes are critical to surface energy balance variations over the Greenland ice sheet, affecting many aspects of its climate, including melt rates, the nature of low-level temperature inversions, the katabatic wind regime and buoyant stability of the atmosphere. Nevertheless, reliable measurements of the radiative fluxes over the ice sheet are few in number, and have been of limited duration and areal distribution (e.g. Ambach, 1960; 1963, Konzelmann et al., 1994, Harding et al., 1995, Van den Broeke, 1996). Hourly GC-Net radiation flux measurements spanning 1995-2001 period have been used to produce a monthly dataset of surface radiation balance components. The measurements are distributed widely across Greenland and incorporate multiple sensors

Summer Arctic sea ice character from satellite microwave data

NASA Technical Reports Server (NTRS)

Carsey, F. D.

1985-01-01

It is pointed out that Arctic sea ice and its environment undergo a number of changes during the summer period. Some of these changes affect the ice cover properties and, in turn, their response to thermal and mechanical forcing throughout the year. The main objective of this investigation is related to the development of a method for estimating the areal coverage of exposed ice, melt ponds, and leads, which are the basic surface variables determining the local surface albedo. The study is based on data obtained in a field investigation conducted from Mould Bay (NWT), Nimbus 5 satellite data, and Seasat data. The investigation demonstrates that microwave data from satellites, especially microwave brightness temperature, provide good data for estimating important characteristics of summer sea ice cover.

The Areal Extent of Continuous Type Gas Accumulations in Lower Silurian Clinton Sands and Medina Group Sandstones of the Appalachian Basin and the Environments Affected by Their Development

USGS Publications Warehouse

Wandrey, C.J.; Ryder, Robert T.; Nuccio, Vito F.; Aggen, Kerry L.

1997-01-01

In order to best preserve and manage our energy and natural resources we must understand the relationships between these resources and the impacts of their development. To further this understanding the U.S. Geological Survey is studying unconventional continuous-type and, to a lesser extent, conventional oil and gas accumulations and the environmental impacts associated with their development. Continuous-type gas accumulations are generally characterized by low matrix permeabilities, large areal extents, and no distinct water contacts. This basin scale map shows the overall extent of these accumulations and the general land use types that may be impacted by their development. The Appalachian Basin has the longest history of oil and gas exploration and production in the United States. Since Drake's Titusville discovery well was drilled in 1859, oil and gas has been continuously produced in the basin. While there is still a great deal of oil and gas production, new field discoveries are rare and relatively small. For most of the second half of the 20th century the Appalachian basin has been considered a mature petroleum province because most of the large plays have already been discovered and developed. One exception to this trend is the Lower Silurian Clinton Sands and Medina Group Gas play which is being developed in New York, Pennsylvania, and Ohio. This continuous-type gas play has been expanding since the early 1970's (see inset maps). In the 1980's economic incentives such as large increases in wellhead prices further stimulated continuous-type gas resource development. Continuous-type gas plays can be large in areal extent and in thickness. 'Sweetspots' (areas of greater prodcution) are hard to predict and generally associated with better than average permeabilities, and enhanced by natural fracture systems. With an overall success rate often approaching 90%, drilling most of the play with closely spaced wells is often the best way to maximize gas recovery. Some positive economic characteristics associated with the development of these continuous-type accumulations are high success rates, low drilling and development costs, and low water production, which results in low water disposal costs. Large areas within the Appalachian basin with good potential for this type of gas accumulation remain to be tested. Positive environmental characteristics include, a clean energy source, low water production, and relatively low surface impact. Some negative characteristics associated with these continuous -type accumulations are low individual well production rates and small well drainage area. Negative environmental characteristics are primarily related to the dense well spacing used to develop the resource to its full potential. Often negative environmental impacts such as surface disturbance can be greatly reduced. The number of well sites can be decreased by using a single centrally located surface location and associated facilities for several directionally or horizonatally drilled wells. This also minimizes the transportation infrastructure (access roads and pipelines) required to maintain the wells and deliver the gas. Visual impacts can be reduced by selecting well locations visible only over short distances. While the prospective area is large, potential decreases basin- ward and toward the northeast and southwest. These areas are represented by the lower potential plays 6727, 6730, and 6731. The U.S. Geological Survey landuse and landcover data was derived from USGS 1:250,000 and 1:100,000 scale maps. This information was collected between the mid 1970s to mid 1980s. The land use and land cover data was mapped and coded using the Anderson classification system (Anderson, 1975) which is a hierarchical system of general (level 1) to more specific (level 2) characterization. Level 1 characterization was used for this map; the land use and land cover designations are displayed below in the Explanation. T

Development of a Novel Multispectral Instrument for Handheld and UAS Measurements of Surface Albedo; First Applications for Glaciers in the Peruvian Andes and for Nevada's Black Rock Desert

NASA Astrophysics Data System (ADS)

Boehmler, J. M.; Stevens, C.; Arnott, W. P.; Watts, A.; All, J.; Schmitt, C. G.

2017-12-01

Accurate atmospheric aerosol characteristics derived from satellite measurements are needed over a variety of land surfaces. Nonhomogeneous and bright surface reflectance across California and Nevada may be a contributing factor in the discrepancies observed between ground based and satellite-retrieved atmospheric aerosol optical depth (AOD). We developed and deployed a compact and portable instrument to measure albedo to evaluate a major factor that influences the accuracy of AOD retrievals. The instrument will be operated on an unmanned aircraft system (UAS) to control areal averaging for comparison with satellite derived albedo from the NASA Moderate Resolution Imaging Spectroradiometer (MODIS). A handheld version of the instrument was mounted on a trekking pole and used for obtaining in situ glacier albedo measurements in the Cordillera Blanca of Peru during the summer of 2017. The instrument weighs approximately 433 g and consists of two parts, a mountable, payload portion (300 g) which houses the sensors, and a handheld screen (133 g) to display real-time data from the payload portion. Both parts are powered by a 9V battery and run on a Teensy 3.6/3.2 microcontroller. To retrieve albedo, two micro-spectrometers manufactured by Hamamatsu Photonics, each with a spectral range of 340 -780 nm, are utilized; one for obtaining the downwelling solar radiation and the other for measuring the solar radiation reflected from the surface. Additional components on the instrument include temperature, pressure and humidity sensors with a one second time response; a GPS for position and altitude; an infrared sensor to measure ground temperature; a digital level and compass for orienting the instrument; a camera for taking photos of the sky and surface; a radio for two-way communication between the screen display and sensor payload; and a micro SD card for recording data. We will present the instrument design along with surface albedo measurements for glaciers of the Peruvian Andes in hand held operation, and for the Black Rock Desert of Nevada in UAS operation.

Current status of validating operational model forecasts at the DWD site Lindenberg

NASA Astrophysics Data System (ADS)

Beyrich, F.; Heret, C.; Vogel, G.

2009-09-01

Based on long experience in the measurement of atmospheric boundary layer parameters, the Meteorological Observatory Lindenberg / Richard - Aßmann-Observatory is well qualified to validate operational NWP results for this location. The validation activities cover a large range of time periods from single days or months up to several years and include much more quantities than generally used in areal verification techniques. They mainly focus on land surface and boundary layer processes which play an important role in the atmospheric forc-ing from the surface. Versatility and continuity of the database enable a comprehensive evaluation of the model behaviour under different meteorological conditions in order to esti-mate the accuracy of the physical parameterisations and to detect possible deficiencies in the predicted processes. The measurements from the boundary layer field site Falkenberg serve as reference data for various types of validation studies: 1. The operational boundary-layer measurements are used to identify and to document weather situations with large forecast errors which can then be analysed in more de-tail. Results from a case study will be presented where model deficiencies in the cor-rect simulation of the diurnal evolution of near-surface temperature under winter con-ditions over a closed snow cover where diagnosed. 2. Due to the synopsis of the boundary layer quantities based on monthly averaged di-urnal cycles systematic model deficiencies can be detected more clearly. Some dis-tinctive features found in the annual cycle (e.g. near-surface temperatures, turbulent heat fluxes and soil moisture) will be outlined. Further aspects are their different ap-pearance in the COSMO-EU and COSMO-DE models as well as the effects of start-ing time (00 or 12 UTC) on the prediction accuracy. 3. The evaluation of the model behaviour over several years provides additional insight into the impact of changes in the physical parameterisations, data assimilation or nu-merics on the meteorological quantities. The temporal development of the error char-acteristics of some near-surface weather parameters (temperature, dewpoint tem-perature, wind velocity) and of the energy fluxes at the surface will be discussed.

Alpha-beta and gamma rhythms subserve feedback and feedforward influences among human visual cortical areas

PubMed Central

Michalareas, Georgios; Vezoli, Julien; van Pelt, Stan; Schoffelen, Jan-Mathijs; Kennedy, Henry; Fries, Pascal

2016-01-01

Primate visual cortex is hierarchically organized. Bottom-up and top-down influences are exerted through distinct frequency channels, as was recently revealed in macaques by correlating inter-areal influences with laminar anatomical projection patterns. Because this anatomical data cannot be obtained in human subjects, we selected seven homologous macaque and human visual areas, and correlated the macaque laminar projection patterns to human inter-areal directed influences as measured with magnetoencephalography. We show that influences along feedforward projections predominate in the gamma band, whereas influences along feedback projections predominate in the alpha-beta band. Rhythmic inter-areal influences constrain a functional hierarchy of the seven homologous human visual areas that is in close agreement with the respective macaque anatomical hierarchy. Rhythmic influences allow an extension of the hierarchy to 26 human visual areas including uniquely human brain areas. Hierarchical levels of ventral and dorsal stream visual areas are differentially affected by inter-areal influences in the alpha-beta band. PMID:26777277

The Role of the Rock on Hydraulic Fracturing of Tight Shales

NASA Astrophysics Data System (ADS)

Suarez-Rivera, R.; Green, S.; Stanchits, S.; Yang, Y.

2011-12-01

Successful economic production of oil and gas from nano-darcy-range permeability, tight shale reservoirs, is achieved via massive hydraulic fracturing. This is so despite their limited hydrocarbon in place, on per unit rock volume basis. As a reference, consider a typical average porosity of 6% and an average hydrocarbon saturation of 50% to 75%. The importance of tight shales results from their large areal extent and vertical thickness. For example, the areal extent of the Anwar field in Saudi Arabia of 3230 square miles (and 300 ft thick), while the Marcellus shale alone is over 100,000 square miles (and 70 to 150 ft thick). The low permeability of the rock matrix, the predominantly mineralized rock fabric, and the high capillary forces to both brines and hydrocarbons, restrict the mobility of pore fluids in these reservoirs. Thus, one anticipates that fluids do not move very far within tight shales. Successful production, therefore results from maximizing the surface area of contact with the reservoir by massive hydraulic fracturing from horizontal bore holes. This was the conceptual breakthrough of the previous decade and the one that triggered the emergence of gas shales, and recently oily shales, as important economic sources of energy. It is now understood that the process can be made substantially more efficient, more sustainable, and more cost effective by understanding the rock. This will be the breakthrough of this decade. Microseismic monitoring, mass balance calculations, and laboratory experiments of hydraulic fracturing on tight shales indicate the development of fracture complexity and fracture propagation that can not be explained in detail in this layered heterogeneous media. It is now clear that in tight shales the large-scale formation fabric is responsible for fracture complexity. For example, the presence and pervasiveness of mineralized fractures, bed interfaces, lithologic contacts, and other types of discontinuities, and their orientation in relation to the in-situ stresses, have a dominant role in promoting fracture branching and abrupt changes in direction. In general, the problem can be conceptualized as a competition between the effect of stresses (traditional mechanics of homogeneous media) and the effect of rock fabric (the mechanics of heterogeneous media). When the stress difference is low and the rock fabric pronounced, the rock fabric defines the direction of propagation. When the stress difference is high and the fabric is weak, the stress contrast dominates the process. In real systems, both effects compete and result in the complexity that we infer from indirect observations. In this paper we discuss the role of rock fabric on fracture complexity during hydraulic fracture propagation. We show that understanding the far field stresses is not enough to understand fracture propagation and complexity. Understanding the rock-specifically the larger-scale textural features that define the reservoir fabric-is fundamental to understand fracture complexity and fracture containment. We use laboratory experiments with acoustic emission localization to monitor fracturing and making inferences about the large-scale rock behavior. We also show that the fracture geometry, even for the same connected surface area, has significant well production and reservoir recovery implications.

Morphogenesis at the inflorescence shoot apex of Anagallis arvensis: surface geometry and growth in comparison with the vegetative shoot.

PubMed

Kwiatkowska, Dorota; Routier-Kierzkowska, Anne-Lise

2009-01-01

Quantitative analysis of geometry and surface growth based on the sequential replica method is used to compare morphogenesis at the shoot apex of Anagallis arvensis in the reproductive and vegetative phases of development. Formation of three types of lateral organs takes place at the Anagallis shoot apical meristem (SAM): vegetative leaf primordia are formed during the vegetative phase and leaf-like bracts and flower primordia during the reproductive phase. Although the shapes of all the three types of primordia are very similar during their early developmental stages, areal growth rates and anisotropy of apex surface growth accompanying formation of leaf or bract primordia are profoundly different from those during formation of flower primordia. This provides an example of different modes of de novo formation of a given shape. Moreover, growth accompanying the formation of the boundary between the SAM and flower primordium is entirely different from growth at the adaxial leaf or bract primordium boundary. In the latter, areal growth rates at the future boundary are the lowest of all the apex surface, while in the former they are relatively very high. The direction of maximal growth rate is latitudinal (along the future boundary) in the case of leaf or bract primordium but meridional (across the boundary) in the case of flower. The replica method does not enable direct analysis of growth in the direction perpendicular to the apex surface (anticlinal direction). Nevertheless, the reconstructed surfaces of consecutive replicas taken from an individual apex allow general directions of SAM surface bulging accompanying primordium formation to be recognized. Precise alignment of consecutive reconstructions shows that the direction of initial bulging during the leaf or bract formation is nearly parallel to the shoot axis (upward bulging), while in the case of flower it is perpendicular to the axis (lateral bulging). In future, such 3D reconstructions can be used to assess displacement velocity fields so that growth in the anticlinal direction can be assessed. In terms of self-perpetuation, the inflorescence SAM of Anagallis differs from the SAM in the vegetative phase in that the centrally located region of slow growth is less distinct in the inflorescence SAM. Moreover, the position of this slowly growing zone with respect to cells is not stable in the course of the meristem ontogeny.

Comprehensive Areal Model of Earthquake-Induced Landslides: Technical Specification and User Guide

USGS Publications Warehouse

Miles, Scott B.; Keefer, David K.

2007-01-01

This report describes the complete design of a comprehensive areal model of earthquakeinduced landslides (CAMEL). This report presents the design process, technical specification of CAMEL. It also provides a guide to using the CAMEL source code and template ESRI ArcGIS map document file for applying CAMEL, both of which can be obtained by contacting the authors. CAMEL is a regional-scale model of earthquake-induced landslide hazard developed using fuzzy logic systems. CAMEL currently estimates areal landslide concentration (number of landslides per square kilometer) of six aggregated types of earthquake-induced landslides - three types each for rock and soil.

Water budgets for selected watersheds in the Delaware River basin, eastern Pennsylvania and western New Jersey

USGS Publications Warehouse

Sloto, Ronald A.; Buxton, Debra E.

2005-01-01

This pilot study, done by the U.S. Geological Survey in cooperation with the Delaware River Basin Commission, developed annual water budgets using available data for five watersheds in the Delaware River Basin with different degrees of urbanization and different geological settings. A basin water budget and a water-use budget were developed for each watershed. The basin water budget describes inputs to the watershed (precipitation and imported water), outputs of water from the watershed (streamflow, exported water, leakage, consumed water, and evapotranspiration), and changes in ground-water and surface-water storage. The water-use budget describes water withdrawals in the watershed (ground-water and surface-water withdrawals), discharges of water in the watershed (discharge to surface water and ground water), and movement of water of water into and out of the watershed (imports, exports, and consumed water). The water-budget equations developed for this study can be applied to any watershed in the Delaware River Basin. Data used to develop the water budgets were obtained from available long-term meteorological and hydrological data-collection stations and from water-use data collected by regulatory agencies. In the Coastal Plain watersheds, net ground-water loss from unconfined to confined aquifers was determined by using ground-water-flow-model simulations. Error in the water-budget terms is caused by missing data, poor or incomplete measurements, overestimated or underestimated quantities, measurement or reporting errors, and the use of point measurements, such as precipitation and water levels, to estimate an areal quantity, particularly if the watershed is hydrologically or geologically complex or the data-collection station is outside the watershed. The complexity of the water budgets increases with increasing watershed urbanization and interbasin transfer of water. In the Wissahickon Creek watershed, for example, some ground water is discharged to streams in the watershed, some is exported as wastewater, and some is exported for public supply. In addition, ground water withdrawn outside the watershed is imported for public supply or imported as wastewater for treatment and discharge in the watershed. A GIS analysis was necessary to quantify many of the water-budget components. The 89.9-square mile East Branch Brandywine Creek watershed in Pennsylvania is a rural watershed with reservoir storage that is underlain by fractured rock. Water budgets were developed for 1977-2001. Average annual precipitation, streamflow, and evapotranspiration were 46.89, 21.58, and 25.88 inches, respectively. Some water was imported (average of 0.68 inches) into the watershed for public-water supply and as wastewater for treatment and discharge; these imports resulted in a net gain of water to the watershed. More water was discharged to East Branch Brandywine Creek than was withdrawn from it; the net discharge resulted in an increase in streamflow. Most ground water was withdrawn (average of 0.25 inches) for public-water supply. Surface water was withdrawn (average of 0.58 inches) for public-water and industrial supply. Discharge of water by sewage-treatment plants and industries (average of 1.22 inches) and regulation by Marsh Creek Reservoir caused base flow to appear an average of 7.2 percent higher than it would have been without these additional sources. On average, 67 percent of the difference was caused by sewage-treatment-plant and industrial discharges, and 33 percent was caused by regulation of the Marsh Creek Reservoir. Water imports, withdrawals, and discharges have been increasing as the watershed becomes increasingly urbanized. The 64-square mile Wissahickon Creek watershed in Pennsylvania is an urban watershed underlain by fractured rock. Water budgets were developed for 1987-98. Average annual precipitation, streamflow, and evapotranspiration were 47.23, 22.24, and 23.12 inches, respectively. The watershed is highly u

Extent of areal inundation of riverine wetlands along five river systems in the upper Hillsborough river watershed, west-central Florida

USGS Publications Warehouse

Lewelling, B.R.

2004-01-01

Riverine and palustrine wetlands are a major ecological component of river basins in west-central Florida. Healthy wetlands are dependent, in part, upon the frequency and duration of periodic flooding or inundation. This report assesses the extent, area, depth, frequency, and duration of periodic flooding and the effects of potential surface-water withdrawals on wetlands along five river systems in the upper Hillsborough River watershed: Hillsborough and New Rivers, Blackwater and Itchepackesassa Creeks, and East Canal. Results of the study were derived from step-backwater analyses performed for each of the river systems using the U.S. Army Corps of Engineers Hydrologic Engineering Center-River Analysis System (HEC-RAS) one-dimensional model. Step-backwater analyses were performed based on daily mean discharges at the 10th, 50th, 70th, 80th, 90th, 95th, 99.5th, and 99.97th percentiles for selected periods. The step-backwater analyses computed extent of inundation, area of inundation, and hydraulic depth. An assessment of the net reduction of areal inundation for each of the selected percentile discharges was computed if 10 percent of the total river flow were diverted for potential withdrawals. The extent of areal inundation at a cross section is controlled by discharge volume, topography, and the degree to which the channel is incised. Areal inundation can occur in reaches characterized by low topographic relief in the upper Hillsborough watershed during most, if not all, selected discharge percentiles. Most river systems in the watershed, however, have well defined and moderately incised channels that generally confine discharges within the banks at the 90th percentile. The greatest increase in inundated area along the five river systems generally occurred between the 95th to 99.5th percentile discharges. The decrease in inundated area that would result from a potential 10-percent discharge withdrawal at the five river systems ranged as follows: Hillsborough River, 7 to 940 acres (2.0 to 6.0 percent); and New River, 0.2 to 58.9 acres (0 to 11.9 percent); Blackwater Creek, 3.3 to 148 acres (2.2 to 9.4 percent); Itchepackesassa Creek, 1.0 to 104 acres (0.9 to 10.8 percent); and East Canal 0.7 to 34.6 acres (0.5 to 7.6 percent).

Assessing the present and future probability of Hurricane Harvey's rainfall

NASA Astrophysics Data System (ADS)

Emanuel, Kerry

2017-11-01

We estimate, for current and future climates, the annual probability of areally averaged hurricane rain of Hurricane Harvey's magnitude by downscaling large numbers of tropical cyclones from three climate reanalyses and six climate models. For the state of Texas, we estimate that the annual probability of 500 mm of area-integrated rainfall was about 1% in the period 1981–2000 and will increase to 18% over the period 2081–2100 under Intergovernmental Panel on Climate Change (IPCC) AR5 representative concentration pathway 8.5. If the frequency of such event is increasingly linearly between these two periods, then in 2017 the annual probability would be 6%, a sixfold increase since the late 20th century.

Precipitation areal-reduction factor estimation using an annual-maxima centered approach

NASA Astrophysics Data System (ADS)

Asquith, W. H.; Famiglietti, J. S.

2000-04-01

The adjustment of precipitation depth of a point storm to an effective (mean) depth over a watershed is important for characterizing rainfall-runoff relations and for cost-effective designs of hydraulic structures when design storms are considered. A design storm is the precipitation point depth having a specified duration and frequency (recurrence interval). Effective depths are often computed by multiplying point depths by areal-reduction factors (ARF). ARF range from 0 to 1, vary according to storm characteristics, such as recurrence interval; and are a function of watershed characteristics, such as watershed size, shape, and geographic location. This paper presents a new approach for estimating ARF and includes applications for the 1-day design storm in Austin, Dallas, and Houston, Texas. The approach, termed "annual-maxima centered," specifically considers the distribution of concurrent precipitation surrounding an annual-precipitation maxima, which is a feature not seen in other approaches. The approach does not require the prior spatial averaging of precipitation, explicit determination of spatial correlation coefficients, nor explicit definition of a representative area of a particular storm in the analysis. The annual-maxima centered approach was designed to exploit the wide availability of dense precipitation gauge data in many regions of the world. The approach produces ARF that decrease more rapidly than those from TP-29. Furthermore, the ARF from the approach decay rapidly with increasing recurrence interval of the annual-precipitation maxima.

Assessing Variations in Areal Organization for the Intrinsic Brain: From Fingerprints to Reliability

PubMed Central

Xu, Ting; Opitz, Alexander; Craddock, R. Cameron; Wright, Margaret J.; Zuo, Xi-Nian; Milham, Michael P.

2016-01-01

Resting state fMRI (R-fMRI) is a powerful in-vivo tool for examining the functional architecture of the human brain. Recent studies have demonstrated the ability to characterize transitions between functionally distinct cortical areas through the mapping of gradients in intrinsic functional connectivity (iFC) profiles. To date, this novel approach has primarily been applied to iFC profiles averaged across groups of individuals, or in one case, a single individual scanned multiple times. Here, we used a publically available R-fMRI dataset, in which 30 healthy participants were scanned 10 times (10 min per session), to investigate differences in full-brain transition profiles (i.e., gradient maps, edge maps) across individuals, and their reliability. 10-min R-fMRI scans were sufficient to achieve high accuracies in efforts to “fingerprint” individuals based upon full-brain transition profiles. Regarding test–retest reliability, the image-wise intraclass correlation coefficient (ICC) was moderate, and vertex-level ICC varied depending on region; larger durations of data yielded higher reliability scores universally. Initial application of gradient-based methodologies to a recently published dataset obtained from twins suggested inter-individual variation in areal profiles might have genetic and familial origins. Overall, these results illustrate the utility of gradient-based iFC approaches for studying inter-individual variation in brain function. PMID:27600846

Synthesis and characterization of prospective polyanionic electrode materials for high performance energy storage applications

NASA Astrophysics Data System (ADS)

Jayachandran, M.; Durai, G.; Vijayakumar, T.

2018-04-01

In the present study, Polyanionic compound (SO4)-group based on Li2Ni(SO4)2 (Lithium Nickel Sulphate) composite electrodes materials were prepared by a ball-milling method and solid-state reaction route. X-ray diffraction analysis confirmed the formation of a polycrystalline orthorhombic phase of composite Li2Ni(SO4)2 with an average crystallite size of about 50.16 nm. Field Emission Scanning electron microscopy investigation reveals the spherical shape particles with the particle size of around 200–500 nm. Raman and FTIR analysis confirms the structural and functional groups of the synthesized materials and also the formation of Li2Ni(SO4)2. The electrochemical measurements using cyclic voltammetry (CV) and galvanostatic charging-discharging (GCD) techniques were carried out to study the electrochemical supercapacitive performance of the composite Li2Ni (SO4)2 electrodes. From the CV investigations, an areal capacitance of 508 mF cm‑2 was obtained at 10 mV s‑1. The galvanostatic charge-discharge (GCD) measurements exhibited the areal capacitance of 101 mF cm‑2 at a constant current density of 2 mA cm‑2 in 2 M KOH. These GCD profiles were linear and also symmetric in nature with the maximum columbic efficiency of about 85%. The electrochemical performance of the composite Li2Ni(SO4)2 electrode material shows excellent performance for supercapacitor applications.

Analysis of the breakdown of the Antarctic circumpolar vortex using TOMS ozone data

NASA Technical Reports Server (NTRS)

Bowman, Kenneth P.

1987-01-01

Climatological analysis of data from the Total Ozone Mapping Spectrometer (TOMS) on the Nimbus 7 satellite has shown that the annual cycles of ozone are very different in the Arctic and Antarctic. The annual cycle in the Arctic is a relatively smooth annual sine wave; but in the Antarctic the circumpolar vortex breaks down rapidly during the Southern Hemisphere spring (September through November), producing a rapid rise in total ozone and a sawtooth-shaped annual cycle. The evolution of the Antarctic total ozone field during the vortex breakdown was studied by computing areally-integrated ozone amounts from the TOMS data. This technique avoids substantial difficulties with using zonally-averaged ozone amounts to study the asymmetric breakdown phenomenon. Variability of total ozone is found to be large both within an individual year and between different years. During the last decade monthly-mean total ozone values in the Antarctic during the springtime vortex breakdown period have decreased dramatically. The ozone-area statistics indicate that the decrease has resulted in part from changes in the timing of the vortex breakdown and resultant ozone increase, which have occurred later during recent years. Analysis of the spatial scales involved in the ozone transport and mixing that occur during the vortex breakdown is now underway. Reliable calculation of diagnostic quantities like areally-integrated ozone is possible only with the high-resolution, two-dimensional, daily coverage provided by the TOMS instrument.

Light transfer in agar immobilized microalgae cell cultures

NASA Astrophysics Data System (ADS)

Kandilian, Razmig; Jesus, Bruno; Legrand, Jack; Pilon, Laurent; Pruvost, Jérémy

2017-09-01

This paper experimentally and theoretically investigates light transfer in agar-immobilized cell cultures. Certain biotechnological applications such as production of metabolites secreted by photosynthetic microorganisms require cells to be immobilized in biopolymers to minimize contamination and to facilitate metabolite recovery. In such applications, light absorption by cells is one of the most important parameters affecting cell growth or metabolite productivity. Modeling light transfer therein can aid design and optimize immobilized-cell reactors. In this study, Parachlorella kessleri cells with areal biomass concentrations ranging from 0.36 to 16.9 g/m2 were immobilized in 2.6 mm thick agar gels. The average absorption and scattering cross-sections as well as the scattering phase function of P. kessleri cells were measured. Then, the absorption and transport scattering coefficients of the agar gel were determined using an inverse method based on the modified two-flux approximation. The forward model was used to predict the normal-hemispherical transmittance and reflectance of the immobilized-cell films accounting for absorption and scattering by both microalgae and the agar gel. Good agreement was found between the measured and predicted normal-hemispherical transmittance and reflectance provided absorption and scattering by agar were taken into account. Moreover, good agreement was found between experimentally measured and predicted mean rate of photon absorption. Finally, optimal areal biomass concentration was determined to achieve complete absorption of the incident radiation.

Areal-reduction factors for the precipitation of the 1-day design storm in Texas

USGS Publications Warehouse

Asquith, William H.

1999-01-01

The reduction of the precipitation depth from a design storm for a point to an effective (mean) depth over a watershed often is important for cost-effective design of hydraulic structures by reducing the volume of precipitation. A design storm for a point is the depth of precipitation that has a specified duration and frequency (recurrence interval). The effective depth can be calculated by multiplying the design-storm depth by an areal-reduction factor (ARF). ARF ranges from 0 to 1, varies with the recurrence interval of the design storm, and is a function of watershed characteristics such as watershed size and shape, geographic location, and time of year that the design storm occurs. This report documents an investigation of ARF by the U.S. Geological Survey, in cooperation with the Texas Department of Transportation, for the 1-day design storm for Austin, Dallas, and Houston, Texas. The ?annual maxima-centered? approach used in this report specifically considers the distribution of concurrent precipitation surrounding an annual precipitation maxima. Unlike previously established approaches, the annual maxima-centered approach does not require the spatial averaging of precipitation nor explicit definition of a representative area of a particular storm in the analysis. Graphs of the relation between ARF and circular watershed area (to about 7,000 square miles) are provided, and a technique to calculate ARF for noncircular watersheds is discussed.

CONFRONTING THE MODIFIABLE AREAL UNIT PROBLEM FOR INFERENCE ON NITRATE IN REGIONAL SHALLOW GROUND WATER

EPA Science Inventory

This work addresses a potentially serious problem in synthesis of
spatially explicit data on ground water quality from wells, known to
geographers as the modifiable areal unit problem (MAUP). Investigators
are faced with choosing a level of aggregation appropriate to
...

Venus Interior Probe Using In-Situ Power and Propulsion (VIP-INSPR)

NASA Technical Reports Server (NTRS)

Bugga, Ratnakumar V.

2016-01-01

Venus, despite being our closest neighboring planet, is under-explored due to its hostile and extreme environment, with a 92 bar pressure and 467 C temperature at the surface. The temperature decreases at higher altitudes, almost at the rate of 7.9 C/km, reaching the Earth surface conditions at 65 km. Due to the less extreme conditions, balloon missions could survive as long as 46 h at an altitude of 54 km. However, because of the opacity of the Venus atmosphere filled with clouds of sulfuric acid and CO2, orbiter or balloon missions are not as revealing and informative in characterizing the surface, as similar missions on Moon and Mars. To understand the evolutionary paths of Venus in relation to Earth, it is imperative to gather basic information on the crust, mantle, core, atmosphere/exosphere and bulk composition of Venus, through in-situ investigations using landers, probes and variable altitude areal platforms.

Aquifer susceptibility to perchlorate contamination in a highly urbanized environment

USGS Publications Warehouse

Woolfenden, Linda R.; Trefly, Michael G.

2007-01-01

Perchlorate contamination from anthropogenic sources has been released into the Rialto-Colton, California, USA, groundwater flow system since the 1940s during its production, distribution, storage, and use. Preliminary analysis of lithological, geophysical, and water-chemistry data provided new understanding of the pathways of perchlorate migration that aid in assessing the susceptibility of drinking-water supplies to contamination within the Rialto-Colton basin. Vertical migration of perchlorate into the main water-producing aquifers is restricted by an areally extensive old soil surface; however, perchlorate data indicate contamination below this soil surface. Possible pathways for the downward migration of the contaminated water include wellbore flow and discontinuities in the old soil surface. Horizontal migration of perchlorate is influenced by lithology and faults within the basin. The basin fill is a heterogeneous mixture of boulders, gravel, sand, silt, and clay, and internal faults may restrict perchlorate migration in some areas.

Superhydrophobicity enhancement through substrate flexibility

NASA Astrophysics Data System (ADS)

Vasileiou, Thomas; Gerber, Julia; Prautzsch, Jana; Schutzius, Thomas; Poulikakos, Dimos

2017-11-01

Inspired by manifestations in nature, micro/nanoengineering superhydrophobic surfaces has been the focus of much work. Generally, hydrophobicity is increased through the combined effects of surface texturing and chemistry; being durable, rigid substrate materials are the norm. However, many natural and technical materials are flexible, and the resulting effect on hydrophobicity has been largely unexplored. Here, we show that the rational tuning of flexibility can work collaboratively with the surface micro/nanotexture to enhance liquid repellency performance, defined by impalement and breakup resistance, contact time reduction, and restitution coefficient increase. Reduction in substrate stiffness and areal density imparts immediate acceleration and intrinsic responsiveness to impacting droplets, mitigating the collision and lowering the impalement probability by 60 % without the need for active actuation. We demonstrate the above discoveries with materials ranging from thin steel or polymer sheets to butterfly wings. Partial support of the Swiss National Science Foundation under Grant 162565 and the European Research Council under Advanced Grant 669908 (INTICE) is acknowledged.

Superhydrophobicity enhancement through substrate flexibility.

PubMed

Vasileiou, Thomas; Gerber, Julia; Prautzsch, Jana; Schutzius, Thomas M; Poulikakos, Dimos

2016-11-22

Inspired by manifestations in nature, microengineering and nanoengineering of synthetic materials to achieve superhydrophobicity has been the focus of much work. Generally, hydrophobicity is enhanced through the combined effects of surface texturing and chemistry; being durable, rigid materials are the norm. However, many natural and technical surfaces are flexible, and the resulting effect on hydrophobicity has been largely ignored. Here, we show that the rational tuning of flexibility can work synergistically with the surface microtexture or nanotexture to enhance liquid repellency performance, characterized by impalement and breakup resistance, contact time reduction, and restitution coefficient increase. Reduction in substrate areal density and stiffness imparts immediate acceleration and intrinsic responsiveness to impacting droplets (∼350 × g), mitigating the collision and lowering the impalement probability by ∼60% without the need for active actuation. Furthermore, we exemplify the above discoveries with materials ranging from man-made (thin steel or polymer sheets) to nature-made (butterfly wings).

Radar signal return from near-shore surface and shallow subsurface features, Darien Province, Panama

NASA Technical Reports Server (NTRS)

Hanson, B. C.; Dellwig, L. F.

1973-01-01

The AN/APQ-97 radar imagery over eastern Panama is analyzed. The imagery was directed toward extraction of geologic and engineering data and the establishment of operational parameters. Subsequent investigations emphasized landform identification and vegetation distribution. The parameters affecting the observed return signal strength from such features are considered. Near-shore ocean phenomena were analyzed. Tidal zone features such as mud flats and reefs were identified in the near range, but were not detectable in the far range. Surface roughness dictated the nature of reflected energy (specular or diffuse). In surf zones, changes in wave train orientation relative to look direction, the slope of the surface, and the physical character of the wave must be considered. It is concluded that the establishment of the areal extent of the tidal flats, distributary channels, and reefs is practical only in the near to intermediate range under minimal low tide conditions.

A significant reduction of ice adhesion on nanostructured surfaces that consist of an array of single-walled carbon nanotubes: A molecular dynamics simulation study

NASA Astrophysics Data System (ADS)

Bao, Luyao; Huang, Zhaoyuan; Priezjev, Nikolai V.; Chen, Shaoqiang; Luo, Kai; Hu, Haibao

2018-04-01

It is well recognized that excessive ice accumulation at low-temperature conditions can cause significant damage to civil infrastructure. The passive anti-icing surfaces provide a promising solution to suppress ice nucleation and enhance ice removal. However, despite extensive efforts, it remains a challenge to design anti-icing surfaces with low ice adhesion. Using all-atom molecular dynamics (MD) simulations, we show that surfaces with single-walled carbon nanotube array (CNTA) significantly reduce ice adhesion due to the extremely low solid areal fraction. It was found that the CNTA surface exhibits up to a 45% decrease in the ice adhesion strength in comparison with the atomically smooth graphene surface. The details of the ice detachment from the CNTA surface were examined for different water-carbon interaction energies and temperatures of the ice cube. Remarkably, the results of MD simulations demonstrate that the ice detaching strength depends linearly on the ratio of the ice-surface interaction energy and the ice temperature. These results open the possibility for designing novel robust surfaces with low ice adhesion for passive anti-icing applications.

The application of iodine and magnetic susceptibility surface geochemical surveys in the Lodgepole Play, Eastern Williston Basin, North Dakota

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

Tedesco, S.A.

1996-06-01

The use of surface geochemistry as a first pass exploration tool is becoming more prevalent in petroleum exploration. This is especially true due to the high cost of 2-D and 3-D surveys in defining small targets such as the Waulsortian mounds of the Lodgepole Formation. Surface geochemical surveys are very effective in pinpointing specific target areas for seismic surveying and thus reducing costs. Presented are examples of surface geochemical surveys utilizing magnetic susceptibility and iodine methods in delineating reservoirs in the Lodgepole, Mission Canyon and Red River formations. The types of surveys presented vary from reconnaissance to detail and examplesmore » of how to define a grid will be discussed. Surface geochemical surveys can be very effective when the areal extent of the target(s) and the purpose of the survey are clearly defined prior to implementation. By determining which areas have microseepage and which areas do not, surface geochemistry can be a very effective tool in focusing exploration efforts and maximizing exploration dollars.« less

Conductive MOF electrodes for stable supercapacitors with high areal capacitance.

PubMed

Sheberla, Dennis; Bachman, John C; Elias, Joseph S; Sun, Cheng-Jun; Shao-Horn, Yang; Dincă, Mircea

2017-02-01

Owing to their high power density and superior cyclability relative to batteries, electrochemical double layer capacitors (EDLCs) have emerged as an important electrical energy storage technology that will play a critical role in the large-scale deployment of intermittent renewable energy sources, smart power grids, and electrical vehicles. Because the capacitance and charge-discharge rates of EDLCs scale with surface area and electrical conductivity, respectively, porous carbons such as activated carbon, carbon nanotubes and crosslinked or holey graphenes are used exclusively as the active electrode materials in EDLCs. One class of materials whose surface area far exceeds that of activated carbons, potentially allowing them to challenge the dominance of carbon electrodes in EDLCs, is metal-organic frameworks (MOFs). The high porosity of MOFs, however, is conventionally coupled to very poor electrical conductivity, which has thus far prevented the use of these materials as active electrodes in EDLCs. Here, we show that Ni 3 (2,3,6,7,10,11-hexaiminotriphenylene) 2 (Ni 3 (HITP) 2 ), a MOF with high electrical conductivity, can serve as the sole electrode material in an EDLC. This is the first example of a supercapacitor made entirely from neat MOFs as active materials, without conductive additives or other binders. The MOF-based device shows an areal capacitance that exceeds those of most carbon-based materials and capacity retention greater than 90% over 10,000 cycles, in line with commercial devices. Given the established structural and compositional tunability of MOFs, these results herald the advent of a new generation of supercapacitors whose active electrode materials can be tuned rationally, at the molecular level.

Conductive MOF electrodes for stable supercapacitors with high areal capacitance

NASA Astrophysics Data System (ADS)

Sheberla, Dennis; Bachman, John C.; Elias, Joseph S.; Sun, Cheng-Jun; Shao-Horn, Yang; Dincă, Mircea

2017-02-01

Owing to their high power density and superior cyclability relative to batteries, electrochemical double layer capacitors (EDLCs) have emerged as an important electrical energy storage technology that will play a critical role in the large-scale deployment of intermittent renewable energy sources, smart power grids, and electrical vehicles. Because the capacitance and charge-discharge rates of EDLCs scale with surface area and electrical conductivity, respectively, porous carbons such as activated carbon, carbon nanotubes and crosslinked or holey graphenes are used exclusively as the active electrode materials in EDLCs. One class of materials whose surface area far exceeds that of activated carbons, potentially allowing them to challenge the dominance of carbon electrodes in EDLCs, is metal-organic frameworks (MOFs). The high porosity of MOFs, however, is conventionally coupled to very poor electrical conductivity, which has thus far prevented the use of these materials as active electrodes in EDLCs. Here, we show that Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 (Ni3(HITP)2), a MOF with high electrical conductivity, can serve as the sole electrode material in an EDLC. This is the first example of a supercapacitor made entirely from neat MOFs as active materials, without conductive additives or other binders. The MOF-based device shows an areal capacitance that exceeds those of most carbon-based materials and capacity retention greater than 90% over 10,000 cycles, in line with commercial devices. Given the established structural and compositional tunability of MOFs, these results herald the advent of a new generation of supercapacitors whose active electrode materials can be tuned rationally, at the molecular level.

Impacts of Microphysical Scheme on Convective and Stratiform Characteristics in Two High Precipitation Squall Line Events

NASA Technical Reports Server (NTRS)

Wu, Di; Dong, Xiquan; Xi, Baike; Feng, Zhe; Kennedy, Aaron; Mullendore, Gretchen; Gilmore, Matthew; Tao, Wei-Kuo

2013-01-01

This study investigates the impact of snow, graupel, and hail processes on simulated squall lines over the Southern Great Plains in the United States. The Weather Research and Forecasting (WRF) model is used to simulate two squall line events in Oklahoma during May 2007, and the simulations are validated against radar and surface observations. Several microphysics schemes are tested in this study, including the WRF 5-Class Microphysics (WSM5), WRF 6-Class Microphysics (WSM6), Goddard Cumulus Ensemble (GCE) Three Ice (3-ice) with graupel, Goddard Two Ice (2-ice), and Goddard 3-ice hail schemes. Simulated surface precipitation is sensitive to the microphysics scheme when the graupel or hail categories are included. All of the 3-ice schemes overestimate the total precipitation with WSM6 having the largest bias. The 2-ice schemes, without a graupel/hail category, produce less total precipitation than the 3-ice schemes. By applying a radar-based convective/stratiform partitioning algorithm, we find that including graupel/hail processes increases the convective areal coverage, precipitation intensity, updraft, and downdraft intensities, and reduces the stratiform areal coverage and precipitation intensity. For vertical structures, simulations have higher reflectivity values distributed aloft than the observed values in both the convective and stratiform regions. Three-ice schemes produce more high reflectivity values in convective regions, while 2-ice schemes produce more high reflectivity values in stratiform regions. In addition, this study has demonstrated that the radar-based convective/stratiform partitioning algorithm can reasonably identify WRF-simulated precipitation, wind, and microphysical fields in both convective and stratiform regions.

Challenge of Near-Field Recording beyond 50.4 Gbit/in2

NASA Astrophysics Data System (ADS)

Kishima, Koichiro; Ichimura, Isao; Saito, Kimihiro; Yamamoto, Kenji; Kuroda, Yuji; Iida, Atsushi; Masuhara, Shin; Osato, Kiyoshi

2002-03-01

The possibility of an areal density over 50 Gbit/in2 was examined in near-field phase-change recording. The disk structure was optimized to maximize readout signals under the land-and-groove recording condition at a tracking pitch of 160 nm. We also evaluated the signal crosstalk from adjacent tracks. Eye diagrams of 50.4 Gbit/in2 areal density were demonstrated using 1.5 \\mathit{NA} optics and a GaN laser diode. The track pitch and linear bit density are 160 nm and 80 nm/bit, respectively. The transmission electron microscope (TEM) micrograph of recorded amorphous marks at an areal density of 50.4 Gbit/in2 is also presented.

Note: Radiochemical measurement of fuel and ablator areal densities in cryogenic implosions at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Hagmann, C.; Shaughnessy, D. A.; Moody, K. J.; Grant, P. M.; Gharibyan, N.; Gostic, J. M.; Wooddy, P. T.; Torretto, P. C.; Bandong, B. B.; Bionta, R.; Cerjan, C. J.; Bernstein, L. A.; Caggiano, J. A.; Herrmann, H. W.; Knauer, J. P.; Sayre, D. B.; Schneider, D. H.; Henry, E. A.; Fortner, R. J.

2015-07-01

A new radiochemical method for determining deuterium-tritium (DT) fuel and plastic ablator (CH) areal densities (ρR) in high-convergence, cryogenic inertial confinement fusion implosions at the National Ignition Facility is described. It is based on measuring the 198Au/196Au activation ratio using the collected post-shot debris of the Au hohlraum. The Au ratio combined with the independently measured neutron down scatter ratio uniquely determines the areal densities ρR(DT) and ρR(CH) during burn in the context of a simple 1-dimensional capsule model. The results show larger than expected ρR(CH) values, hinting at the presence of cold fuel-ablator mix.

Areal Mass Oscillations in Planar Targets Due to Feedout: Theory and Simulations.

NASA Astrophysics Data System (ADS)

Velikovich, A. L.; Schmitt, A. J.; Karasik, M.; Obenschain, S. P.; Serlin, V.; Pawley, C. J.; Gardner, J. H.; Aglitskiy, Y.; Metzler, N.

2001-10-01

When a planar shock wave breaks out at a rippled rear surface of a laser-driven target, the lateral pressure gradient in a rippled rarefaction wave propagating back to the front surface causes a lateral mass redistribution that reverses the phase of mass variation. If the driving laser pulse has no foot, then the RT growth, starting when the rarefaction wave reaches the front surface, causes the second phase reversal of mass variation, and continues at the initial phase, as consistently observed in feedout experiments on Nike. A foot of the laser pulse can cause an early phase reversal of mass variation, making the strong shock wave driven by the main pulse interact with a density variation in a rippled rarefaction wave rather than with static rear surface ripples. Theory and simulations predict that this interaction can make the phase of mass variation reverse one or three times. Then the phase of the RT growing mode would be opposite to that of the initial mass variation.

Computer program for simulation of variable recharge with the U. S. Geological Survey modular finite-difference ground-water flow model (MODFLOW)

USGS Publications Warehouse

Kontis, A.L.

2001-01-01

The Variable-Recharge Package is a computerized method designed for use with the U.S. Geological Survey three-dimensional finitedifference ground-water flow model (MODFLOW-88) to simulate areal recharge to an aquifer. It is suitable for simulations of aquifers in which the relation between ground-water levels and land surface can affect the amount and distribution of recharge. The method is based on the premise that recharge to an aquifer cannot occur where the water level is at or above land surface. Consequently, recharge will vary spatially in simulations in which the Variable- Recharge Package is applied, if the water levels are sufficiently high. The input data required by the program for each model cell that can potentially receive recharge includes the average land-surface elevation and a quantity termed ?water available for recharge,? which is equal to precipitation minus evapotranspiration. The Variable-Recharge Package also can be used to simulate recharge to a valley-fill aquifer in which the valley fill and the adjoining uplands are explicitly simulated. Valley-fill aquifers, which are the most common type of aquifer in the glaciated northeastern United States, receive much of their recharge from upland sources as channeled and(or) unchanneled surface runoff and as lateral ground-water flow. Surface runoff in the uplands is generated in the model when the applied water available for recharge is rejected because simulated water levels are at or above land surface. The surface runoff can be distributed to other parts of the model by (1) applying the amount of the surface runoff that flows to upland streams (channeled runoff) to explicitly simulated streams that flow onto the valley floor, and(or) (2) applying the amount that flows downslope toward the valley- fill aquifer (unchanneled runoff) to specified model cells, typically those near the valley wall. An example model of an idealized valley- fill aquifer is presented to demonstrate application of the method and the type of information that can be derived from its use. Documentation of the Variable-Recharge Package is provided in the appendixes and includes listings of model code and of program variables. Comment statements in the program listings provide a narrative of the code. Input-data instructions and printed model output for the package are included.

Calibration of remotely sensed proportion or area estimates for misclassification error

Treesearch

Raymond L. Czaplewski; Glenn P. Catts

1992-01-01

Classifications of remotely sensed data contain misclassification errors that bias areal estimates. Monte Carlo techniques were used to compare two statistical methods that correct or calibrate remotely sensed areal estimates for misclassification bias using reference data from an error matrix. The inverse calibration estimator was consistently superior to the...

An enhanced CCRTM (E-CCRTM) damage imaging technique using a 2D areal scan for composite plates

NASA Astrophysics Data System (ADS)

He, Jiaze; Yuan, Fuh-Gwo

2016-04-01

A two-dimensional (2-D) non-contact areal scan system was developed to image and quantify impact damage in a composite plate using an enhanced zero-lag cross-correlation reverse-time migration (E-CCRTM) technique. The system comprises a single piezoelectric actuator mounted on the composite plate and a laser Doppler vibrometer (LDV) for scanning a region to capture the scattered wavefield in the vicinity of the PZT. The proposed damage imaging technique takes into account the amplitude, phase, geometric spreading, and all of the frequency content of the Lamb waves propagating in the plate; thus, the reflectivity coefficients of the delamination can be calculated and potentially related to damage severity. Comparisons are made in terms of damage imaging quality between 2-D areal scans and linear scans as well as between the proposed and existing imaging conditions. The experimental results show that the 2-D E-CCRTM performs robustly when imaging and quantifying impact damage in large-scale composites using a single PZT actuator with a nearby areal scan using LDV.

An evaluation of object-oriented image analysis techniques to identify motorized vehicle effects in semi-arid to arid ecosystems of the American West

USGS Publications Warehouse

Mladinich, C.

2010-01-01

Human disturbance is a leading ecosystem stressor. Human-induced modifications include transportation networks, areal disturbances due to resource extraction, and recreation activities. High-resolution imagery and object-oriented classification rather than pixel-based techniques have successfully identified roads, buildings, and other anthropogenic features. Three commercial, automated feature-extraction software packages (Visual Learning Systems' Feature Analyst, ENVI Feature Extraction, and Definiens Developer) were evaluated by comparing their ability to effectively detect the disturbed surface patterns from motorized vehicle traffic. Each package achieved overall accuracies in the 70% range, demonstrating the potential to map the surface patterns. The Definiens classification was more consistent and statistically valid. Copyright ?? 2010 by Bellwether Publishing, Ltd. All rights reserved.

Neocortical arealization: evolution, mechanisms, and open questions.

PubMed

Alfano, Christian; Studer, Michèle

2013-06-01

The mammalian neocortex is a structure with no equals in the vertebrates and is the seat of the highest cerebral functions, such as thoughts and consciousness. It is radially organized into six layers and tangentially subdivided into functional areas deputed to the elaboration of sensory information, association between different stimuli, and selection and triggering of voluntary movements. The process subdividing the neocortical field into several functional areas is called "arealization". Each area has its own cytoarchitecture, connectivity, and peculiar functions. In the last century, several neuroscientists have investigated areal structure and the mechanisms that have led during evolution to the rising of the neocortex and its organization. The extreme conservation in the positioning and wiring of neocortical areas among different mammalian families suggests a conserved genetic program orchestrating neocortical patterning. However, the impressive plasticity of the neocortex, which is able to rewire and reorganize areal structures and connectivity after impairments of sensory pathways, argues for a more complex scenario. Indeed, even if genetics and molecular biology helped in identifying several genes involved in the arealization process, the logic underlying the neocortical bauplan is still beyond our comprehension. In this review, we will introduce the present knowledge and hypotheses on the ontogenesis and evolution of neocortical areas. Then, we will focus our attention on some open issues, which are still unresolved, and discuss some recent studies that might open new directions to be explored in the next few years. Copyright © 2012 Wiley Periodicals, Inc.

Air-Flow Navigated Crystal Growth for TIPS Pentacene-Based Organic Thin-Film Transistors

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

He, Zhengran; Chen, Jihua; Sun, Zhenzhong

2012-01-01

6,13-bis(triisopropylsilylethynyl)pentacene (TIPS pentacene) is a promising active channel material of organic thin-film transistors (OTFTs) due to its solubility, stability, and high mobility. However, the growth of TIPS pentacene crystals is intrinsically anisotropic and thus leads to significant variation in the performance of OTFTs. In this paper, air flow is utilized to effectively reduce the TIPS pentacene crystal anisotropy and enhance performance consistency in OTFTs, and the resulted films are examined with optical microscopy, grazing-incidence X-ray diffraction, and thin-film transistor measurements. Under air-flow navigation (AFN), TIPS pentacene drop-cast from toluene solution has been observed to form thin films with improved crystalmore » orientation and increased areal coverage on substrates, which subsequently lead to a four-fold increase of average hole mobility and one order of magnitude enhancement in performance consistency defined by the ratio of average mobility to the standard deviation of the field-effect mobilities.« less

Spatial clustering of average risks and risk trends in Bayesian disease mapping.

PubMed

Anderson, Craig; Lee, Duncan; Dean, Nema

2017-01-01

Spatiotemporal disease mapping focuses on estimating the spatial pattern in disease risk across a set of nonoverlapping areal units over a fixed period of time. The key aim of such research is to identify areas that have a high average level of disease risk or where disease risk is increasing over time, thus allowing public health interventions to be focused on these areas. Such aims are well suited to the statistical approach of clustering, and while much research has been done in this area in a purely spatial setting, only a handful of approaches have focused on spatiotemporal clustering of disease risk. Therefore, this paper outlines a new modeling approach for clustering spatiotemporal disease risk data, by clustering areas based on both their mean risk levels and the behavior of their temporal trends. The efficacy of the methodology is established by a simulation study, and is illustrated by a study of respiratory disease risk in Glasgow, Scotland. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nearest Neighbor Averaging and its Effect on the Critical Level and Minimum Detectable Concentration for Scanning Radiological Survey Instruments that Perform Facility Release Surveys.

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

Fournier, Sean Donovan; Beall, Patrick S; Miller, Mark L

2014-08-01

Through the SNL New Mexico Small Business Assistance (NMSBA) program, several Sandia engineers worked with the Environmental Restoration Group (ERG) Inc. to verify and validate a novel algorithm used to determine the scanning Critical Level (L c ) and Minimum Detectable Concentration (MDC) (or Minimum Detectable Areal Activity) for the 102F scanning system. Through the use of Monte Carlo statistical simulations the algorithm mathematically demonstrates accuracy in determining the L c and MDC when a nearest-neighbor averaging (NNA) technique was used. To empirically validate this approach, SNL prepared several spiked sources and ran a test with the ERG 102F instrumentmore » on a bare concrete floor known to have no radiological contamination other than background naturally occurring radioactive material (NORM). The tests conclude that the NNA technique increases the sensitivity (decreases the L c and MDC) for high-density data maps that are obtained by scanning radiological survey instruments.« less

Spatial variability of extreme rainfall at radar subpixel scale

NASA Astrophysics Data System (ADS)

Peleg, Nadav; Marra, Francesco; Fatichi, Simone; Paschalis, Athanasios; Molnar, Peter; Burlando, Paolo

2018-01-01

Extreme rainfall is quantified in engineering practice using Intensity-Duration-Frequency curves (IDF) that are traditionally derived from rain-gauges and more recently also from remote sensing instruments, such as weather radars. These instruments measure rainfall at different spatial scales: rain-gauge samples rainfall at the point scale while weather radar averages precipitation on a relatively large area, generally around 1 km2. As such, a radar derived IDF curve is representative of the mean areal rainfall over a given radar pixel and neglects the within-pixel rainfall variability. In this study, we quantify subpixel variability of extreme rainfall by using a novel space-time rainfall generator (STREAP model) that downscales in space the rainfall within a given radar pixel. The study was conducted using a unique radar data record (23 years) and a very dense rain-gauge network in the Eastern Mediterranean area (northern Israel). Radar-IDF curves, together with an ensemble of point-based IDF curves representing the radar subpixel extreme rainfall variability, were developed fitting Generalized Extreme Value (GEV) distributions to annual rainfall maxima. It was found that the mean areal extreme rainfall derived from the radar underestimate most of the extreme values computed for point locations within the radar pixel (on average, ∼70%). The subpixel variability of rainfall extreme was found to increase with longer return periods and shorter durations (e.g. from a maximum variability of 10% for a return period of 2 years and a duration of 4 h to 30% for 50 years return period and 20 min duration). For the longer return periods, a considerable enhancement of extreme rainfall variability was found when stochastic (natural) climate variability was taken into account. Bounding the range of the subpixel extreme rainfall derived from radar-IDF can be of major importance for different applications that require very local estimates of rainfall extremes.

Transforming geographic scale: a comparison of combined population and areal weighting to other interpolation methods.

PubMed

Hallisey, Elaine; Tai, Eric; Berens, Andrew; Wilt, Grete; Peipins, Lucy; Lewis, Brian; Graham, Shannon; Flanagan, Barry; Lunsford, Natasha Buchanan

2017-08-07

Transforming spatial data from one scale to another is a challenge in geographic analysis. As part of a larger, primary study to determine a possible association between travel barriers to pediatric cancer facilities and adolescent cancer mortality across the United States, we examined methods to estimate mortality within zones at varying distances from these facilities: (1) geographic centroid assignment, (2) population-weighted centroid assignment, (3) simple areal weighting, (4) combined population and areal weighting, and (5) geostatistical areal interpolation. For the primary study, we used county mortality counts from the National Center for Health Statistics (NCHS) and population data by census tract for the United States to estimate zone mortality. In this paper, to evaluate the five mortality estimation methods, we employed address-level mortality data from the state of Georgia in conjunction with census data. Our objective here is to identify the simplest method that returns accurate mortality estimates. The distribution of Georgia county adolescent cancer mortality counts mirrors the Poisson distribution of the NCHS counts for the U.S. Likewise, zone value patterns, along with the error measures of hierarchy and fit, are similar for the state and the nation. Therefore, Georgia data are suitable for methods testing. The mean absolute value arithmetic differences between the observed counts for Georgia and the five methods were 5.50, 5.00, 4.17, 2.74, and 3.43, respectively. Comparing the methods through paired t-tests of absolute value arithmetic differences showed no statistical difference among the methods. However, we found a strong positive correlation (r = 0.63) between estimated Georgia mortality rates and combined weighting rates at zone level. Most importantly, Bland-Altman plots indicated acceptable agreement between paired arithmetic differences of Georgia rates and combined population and areal weighting rates. This research contributes to the literature on areal interpolation, demonstrating that combined population and areal weighting, compared to other tested methods, returns the most accurate estimates of mortality in transforming small counts by county to aggregated counts for large, non-standard study zones. This conceptually simple cartographic method should be of interest to public health practitioners and researchers limited to analysis of data for relatively large enumeration units.

Trends in ground-water levels in Wisconsin through 1966

USGS Publications Warehouse

Devaul, Robert W.

1967-01-01

The water supplies of Wisconsin are the State's most valuable natural resource. Although the State has abundant water supplies to maintain the perennial flow of most streams, and to sustain large increases in municipal, agricultural, and industrial use in many areas, the available supply is not distributed equally throughout the State, either areally or in time. Intelligent development of all water resources depends on knowledge of the occurrence, distribution and movement of water, the amount of discharge to and from a region, the interrelationship of ground and surface water, and the quantity and quality of the water available.

Water-quality assessment of the Lower Susquehanna River Basin, Pennsylvania and Maryland; sources, characteristics, analysis and limitations of nutrient and suspended-sediment data, 1975-90

USGS Publications Warehouse

Hainly, R.A.; Loper, C.A.

1997-01-01

This report describes analyses of available information on nutrients and suspended sediment collected in the Lower Susquehanna River Basin during water years 1975-90. Most of the analyses were applied to data collected during water years 1980-89. The report describes the spatial and temporal availability of nutrient and suspended-sediment data and presents a preliminary concept of the spatial and temporal patterns of concentrations and loads within the basin. Where data were available, total and dissolved forms of nitrogen and phosphorus species from precipitation, surface water, ground water, and springwater, and bottom material from streams and reservoirs were evaluated. Suspended-sediment data from streams also were evaluated. The U.S. Geological Survey National Water Information System (NWIS) database was selected as the primary database for the analyses. Precipitation-quality data from the National Atmospheric Deposition Program (NADP) and bottom-material-quality data from the National Uranium Resource Evaluation (NURE) were used to supplement the water-quality data from NWIS. Concentrations of nutrients were available from 3 precipitation sites established for longterm monitoring purposes, 883 wells (854 synoptic areal survey sites and 29 project and research sites), 23 springs (17 synoptic areal survey sites and 6 project and research sites), and 894 bottom-material sites (840 synoptic areal survey sites and 54 project and research sites). Concentrations of nutrients and (or) suspended sediment were available from 128 streams (36 long-term monitoring sites, 51 synoptic areal survey sites, and 41 project and research sites). Concentrations of nutrients and suspended sediment in streams varied temporally and spatially and were related to land use, agricultural practices, and streamflow. A general north-to-south pattern of increasing median nitrate concentrations, from 2 to 5 mg/L, was detected in samples collected in study unit streams. In streams that drain areas dominated by agriculture, concentrations of nutrients and suspended sediment tend to be elevated with respect to those found in areas of other land-use types and are related to the amount of commercial fertilizer and animal manure applied to the area drained by the streams. Animal manure is the dominant source of nitrogen for the streams in the lower, agricultural part of the basin. Concentrations of nutrients in samples from wells varied with season and well depth and were related to hydrogeologic setting. Median concentrations of nitrate were 2.5 and 3.5 mg/L for wells drawing water at depths of 0 to 100 ft and 101 to 200 ft, respectively. The lowest median concentrations for nitrate in ground water from wells were generally found in siliciclastic-bedrock, forested settings of the Ridge and Valley Physiographic Province, and the highest were found in carbonate-bedrock agricultural settings of the Piedmont Physiographic Province. Twenty-five percent of the measurements from wells in carbonate rocks in the Piedmont Physiographic Province exceeded the Pennsylvania drinking-water standard. An estimate of mass balance of nutrient loads within the Lower Susquehanna River Basin was produced by combining the available information on stream loads, atmosphericdeposition loads, commercial-fertilizer applications, animal-manure production, privateseptic-system nonpoint-source loads, and municipal and industrial point-source loads. The percentage of the average annual nitrate load carried in base flow of streams in the study unit ranged from 45 to 76 percent, and the average annual phosphorus load carried in base flow ranged from 20 to 33 percent. Average annual yields of nutrients and suspended sediment from tributary basins are directly related to percentage of drainage area in agriculture and inversely to drainage area. Information required to compute loads of nitrogen and phosphorus were available for all sources except atmospheric deposition, for which only nitrogen data were available. Atmospheric deposition is the dominant source of nitrogen for the mostly forested basins draining the upper half of the study unit. The estimate of total annual nitrogen load to the study unit from precipitation is 98.8 million pounds. Nonpoint and point sources of nutrients were estimated. Nonpoint and point sources combined, including atmospheric deposition, provide a potential annual load of 390 million pounds of nitrogen and 79.5 million pounds of phosphorus. The range of percentages of the estimated nonpoint and point sources that were measured in the stream was 20 to 47 percent for nitrogen and 6 to 14 percent for phosphorus. On the average, the Susquehanna River discharges 141,000 pounds of nitrogen and 7,920 pounds of phosphorus to the Lower Susquehanna River reservoir system each year. About 98 percent of the nitrogen and 60 percent of the phosphorus passes through the reservoir system. Interpretations of available water-quality data and conclusions about the water quality of the Lower Susquehanna River Basin were limited by the scarcity of certain types of water-quality data and current ancillary data. A more complete assessment of the water quality of the basin with respect to nutrients and suspended sediment would be enhanced by the availability of additional data for multiple samples over time from all water environments; samples from streams in the northern and western part of the basin; samples from streams and springs throughout the basin during high base-flow or stormflow conditions; and information on current land-use, and nutrient loading from all types of land-use settings.

Low Altitude AVIRIS Data for Mapping Land Form Types on West Ship Island, Mississippi

NASA Technical Reports Server (NTRS)

Spruce, Joseph P.; Otvos, Ervin G.; Giardino, Marco J.

2002-01-01

Barrier islands help protect the southern and southeastern U.S. shoreline from hurricanes and severe storms. They are important for coastal resource management and geologic research, especially in studies that involve changes in island areas and surface environments, and they display a dynamically changing and diverse mix of landform and vegetative cover habitats. Many Gulf Coast barrier islands have undergone dramatic decreases in areal extent, often due to hurricane and severe storm damage. For example, Louisiana's barrier islands have lost 55 percent of their surface area over the past 100 years. Aerial photography and Landsat data have been used to monitor changes in barrier island areal extent, although neither data source is optimal for making maps of detailed landform types at site-specific scales. High spatial resolution hyperspectral imagery, such as that obtained from the high spatial resolution Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) sensor, may enable improved mapping of landform types, which would benefit studies of the dynamics of barrier island environments. During the summers of 2000 and 2001, a study was conducted to assess low-altitude AVIRIS data for mapping the landform types of West Ship Island, a barrier island in Harrison County, Mississippi. This study area was selected because of the availability of low-altitude AVIRIS data acquired on July 22, 1999, and because of the area's accessibility to the investigating team. West Ship Island is one of the six barrier islands that belong to the Gulf Shores National Seashore, which is managed by the National Park Service. This island contains an impressive range of landform categories. Surface types include beach, dune, and sand flat environments. West Ship Island also harbors Fort Massachusetts, a historic fort used during the Civil War. Because it is located near Stennis Space Center, the island is frequently imaged by NASA's airborne and spaceborne sensors.

A method to combine remotely sensed and in situ measurements: Program documentation

NASA Technical Reports Server (NTRS)

Peck, E. L.; Johnson, E. R.; Wong, M. Y.

1984-01-01

All user and programmer information required for using the correlation area method (CAM) program is presented. This program combines measurements of hydrologic variables from all measurement technologies to produce estimated areal mean values. The method accounts for sampling geometries and measurement accuracies and provides a measure of the accuracy of the estimated mean areal value.

Understanding controls of hydrologic processes across two headwater monolithological catchments using model-data synthesis

NASA Astrophysics Data System (ADS)

Xiao, D.; Shi, Y.; Hoagland, B.; Del Vecchio, J.; Russo, T. A.; DiBiase, R. A.; Li, L.

2017-12-01

How do watershed hydrologic processes differ in catchments derived from different lithology? This study compares two first order, deciduous forest watersheds in Pennsylvania, a sandstone watershed, Garner Run (GR, 1.34 km2), and a shale-derived watershed, Shale Hills (SH, 0.08 km2). Both watersheds are simulated using a combination of national datasets and field measurements, and a physics-based land surface hydrologic model, Flux-PIHM. We aim to evaluate the effects of lithology on watershed hydrology and assess if we can simulate a new watershed without intensive measurements, i.e., directly use calibration information from one watershed (SH) to reproduce hydrologic dynamics of another watershed (GR). Without any calibration, the model at GR based on national datasets and calibration inforamtion from SH cannot capture some discharge peaks or the baseflow during dry periods. The model prediction agrees well with the GR field discharge and soil moisture after calibrating the soil hydraulic parameters using the uncertainty based Hornberger-Spear-Young algorithm and the Latin Hypercube Sampling method. Agreeing with the field observation and national datasets, the difference in parameter values shows that the sandstone watershed has a larger averaged soil pore diameter, greater water storage created by porosity, lower water retention ability, and greater preferential flow. The water budget calculation shows that the riparian zone and the colluvial valley serves as buffer zones that stores water at GR. Using the same procedure, we compared Flux-PIHM simulations with and without a field measured surface boulder map at GR. When the boulder map is used, the prediction of areal averaged soil moisture is improved, without performing extra calibration. When calibrated separately, the cases with or without boulder map yield different calibration values, but their hydrologic predictions are similar, showing equifinality. The calibrated soil hydraulic parameter values in the with boulder map case is more physically plausible than the without boulder map case. We switched the topography and soil properties between GR and SH, and results indicate that the hydrologic processes are more sensitive to changes in domain topography than to changes in the soil properties.

New horizons in selective laser sintering surface roughness characterization

NASA Astrophysics Data System (ADS)

Vetterli, M.; Schmid, M.; Knapp, W.; Wegener, K.

2017-12-01

Powder-based additive manufacturing of polymers and metals has evolved from a prototyping technology to an industrial process for the fabrication of small to medium series of complex geometry parts. Unfortunately due to the processing of powder as a basis material and the successive addition of layers to produce components, a significant surface roughness inherent to the process has been observed since the first use of such technologies. A novel characterization method based on an elastomeric pad coated with a reflective layer, the Gelsight, was found to be reliable and fast to characterize surfaces processed by selective laser sintering (SLS) of polymers. With help of this method, a qualitative and quantitative investigation of SLS surfaces is feasible. Repeatability and reproducibility investigations are performed for both 2D and 3D areal roughness parameters. Based on the good results, the Gelsight is used for the optimization of vertical SLS surfaces. A model built on laser scanning parameters is proposed and after confirmation could achieve a roughness reduction of 10% based on the S q parameter. The Gelsight could be successfully identified as a fast, reliable and versatile surface topography characterization method as it applies to all kind of surfaces.

Quantitative image analysis for evaluating the abrasion resistance of nanoporous silica films on glass

PubMed Central

Nielsen, Karsten H.; Karlsson, Stefan; Limbach, Rene; Wondraczek, Lothar

2015-01-01

The abrasion resistance of coated glass surfaces is an important parameter for judging lifetime performance, but practical testing procedures remain overly simplistic and do often not allow for direct conclusions on real-world degradation. Here, we combine quantitative two-dimensional image analysis and mechanical abrasion into a facile tool for probing the abrasion resistance of anti-reflective (AR) coatings. We determine variations in the average coated area, during and after controlled abrasion. Through comparison with other experimental techniques, we show that this method provides a practical, rapid and versatile tool for the evaluation of the abrasion resistance of sol-gel-derived thin films on glass. The method yields informative data, which correlates with measurements of diffuse reflectance and is further supported by qualitative investigations through scanning electron microscopy. In particular, the method directly addresses degradation of coating performance, i.e., the gradual areal loss of antireflective functionality. As an exemplary subject, we studied the abrasion resistance of state-of-the-art nanoporous SiO2 thin films which were derived from 5–6 wt% aqueous solutions of potassium silicates, or from colloidal suspensions of SiO2 nanoparticles. It is shown how abrasion resistance is governed by coating density and film adhesion, defining the trade-off between optimal AR performance and acceptable mechanical performance. PMID:26656260

TRMM Microwave Radiometer Rain Rate Estimation Method with Convective and Stratiform Discrimination

NASA Technical Reports Server (NTRS)

Prabhakara, Cuddapah; Iacovazzi, R.; Weinman, J. A.; Dalu, G.; Einaudi, Franco (Technical Monitor)

2000-01-01

Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) radiometer brightness temperature data in the 85 GHz channel (T85) reveal distinct local minima (T85min) in a regional map containing a Mesoscale Convective System (MCS). A map of surface rain rate for that region, deduced from simultaneous measurements made by the Precipitation Radar (PR) on board the TRMM satellite, reveals that these T85min, produced by scattering, correspond to local PR rain maxima. Utilizing the PR rain rate map as a guide, we have developed a TMI algorithm to retrieve convective and stratiform rain. In this algorithm, two parameters are used to classify three kinds of thunderstorms (Cbs) based on the T85 data: a) the magnitude of scattering depression deduced from local T85mi, and b) the mean horizontal gradient of T85 around such minima. Initially, the algorithm is optimized or tuned utilizing the PR and TMI data of a few MCS events. The areal distribution of light (1-10 mm/hr), moderate (10-20 mm/hr), and intense (greater than or equal to 20 mm/hr) rain rates are retrieved on the average with an accuracy of about 15%. Taking advantage of this ability of our retrieval method, one could derive the latent heat input into the atmosphere over the 760 km wide swath of the TMI radiometer in the tropics.

Water relations in cutover peatlands

NASA Astrophysics Data System (ADS)

Price, Jonathan S.; Ketcheson, Scott J.

Sphagnum mosses, the dominant peat-forming plant in many northern peatlands, generally do not regenerate spontaneously in mined peatlands because water transfer between the cutover peat and incipient moss diaspores cannot overcome the capillary barrier effect between the two hydraulically distinct layers. Artificial drainage networks established throughout peatlands, coupled with the removal of the acrotelm during the peat extraction process, drastically alter the natural system function through the exposure of more decomposed catotelm peat and increased compression, oxidation, and shrinkage, subsequently decreasing average pore diameter and enhancing this capillary barrier effect. Water table (WT) fluctuations, constrained within the reduced specific yield of the altered catotelm, exhibit increased variability and rapid decline. The increased effective stress caused by a declining WT can result in seasonal surface subsidence of 8 to 10 cm, thereby reducing saturated hydraulic conductivity by three orders of magnitude. Restoration efforts aim to alter the disturbed hydrological regime, creating conditions more favorable for the recolonization of Sphagnum mosses and the ultimate reestablishment of an upper acrotelm layer. Due to the large areal coverage and high organic carbon content, the response of peatlands to disturbances caused by resource extraction, and their return to functioning ecosystems, must be thoroughly addressed. This paper integrates both published and unpublished work to facilitate an overview of our understanding of the hydrological impact of peat cutting and its implications for restoration.

Highly-wrinkled reduced graphene oxide-conductive polymer fibers for flexible fiber-shaped and interdigital-designed supercapacitors

NASA Astrophysics Data System (ADS)

Li, Bo; Cheng, Jianli; Wang, Zhuanpei; Li, Yinchuan; Ni, Wei; Wang, Bin

2018-02-01

Flexible supercapacitors have attracted great interest due to outstanding flexibility and light weight. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) fibers have the great potential in using as electrodes for flexible supercapacitors due to the good flexibility. However, the reported conductivity and specific capacitance of these PEDOT: PSS fibers are not very high, which limit their electrochemical performances. In this work, composite fibers of reduced graphene oxide(rGO)-PEDOT: PSS with a highly-wrinkled structure on the surface and pores inside are prepared by wet spinning. The fibers with different ratios of graphene to PEDOT:PSS show a distinctly enhanced conductivity up to ca. 590 S·cm-1 and high strength up to ca. 18.4 MPa. Meanwhile, the composite fibers show an improved electrochemical performances, including a high specific areal capacitance of 131 mF cm-2 and high specific areal energy density of 4.55 μWh·cm-2. The flexible supercapacitors including fiber-shaped supercapacitors and interdigital designed supercapacitors not only could work in different bending states without obvious capacitance decay, but also have small leakage current. The interdigital design can further improve the performances of composite fibers with high capacitance and high utilization compared with traditional parallel connected structure.

Effect of Areal Density of Polymer Chains on Gold Nanoparticles on Nanoparticle Location in a Block Copolymer Template

NASA Astrophysics Data System (ADS)

Kim, B. J.; Bang, J.; Hawker, C. J.; Kramer, E. J.

2006-03-01

It is well established that one block of a copolymer can interact preferentially with an inorganic substrate to produce wetting and domain orientation. We take advantage of this preferential interaction to control the location of 2.5 nm diameter Au nanoparticles coated with short thiol-terminated polystyrene (Mn=3.4 kg/mol) chains (PS-SH) in a symmetric poly(styrene-b-2 vinyl-pyridine) (PS-b-P2VP) diblock copolymer (Mn=196 kg/mol) by changing the areal density σ of the PS-SH on the Au. If σ >= 1.6 chains/nm^2, the preferential interaction between the P2VP of the PS-b-P2VP and the Au surface is screened and the Au localizes in the center of the PS domains. If σ <= 1.4 chains/nm^2 , the Au particles are localized at the PS-P2VP interface. Au nanoparticles coated with thiol terminated P2VP (Mn=3 kg/mol) localize in the center of the P2VP domain of the PS-P2VP over the entire range of σ, demonstrating the localization of the PS coated Au nanoparticles at the interface at low values of σ is due to the unscreened Au-P2VP interaction.

Multidimensional Cyclic Voltammetry Simulations of Pseudocapacitive Electrodes with a Conducting Nanorod Scaffold

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

Mei, Bing-Ang; Li, Bin; Lin, Jie

This paper aims to understand the effect of nanoarchitecture on the performance of pseudocapacitive electrodes consisting of conducting scaffold coated with pseudocapacitive material. To do so, two-dimensional numerical simulations of ordered conducting nanorods coated with a thin film of pseudocapacitive material were performed. The simulations reproduced three-electrode cyclic voltammetry measurements based on a continuum model derived from first principles. Two empirical approaches commonly used experimentally to characterize the contributions of surface-controlled and diffusion-controlled charge storage mechanisms to the total current density with respect to scan rate were theoretically validated for the first time. Moreover, the areal capacitive capacitance, attributed tomore » EDL formation, remained constant and independent of electrode dimensions, at low scan rates. However, at high scan rates, it decreased with decreasing conducting nanorod radius and increasing pseudocapacitive layer thickness due to resistive losses. By contrast, the gravimetric faradaic capacitance, due to reversible faradaic reactions, decreased continuously with increasing scan rate and pseudocapacitive layer thickness but was independent of conducting nanorod radius. Note that the total gravimetric capacitance predicted numerically featured values comparable to experimental measurements. Finally, an optimum pseudocapacitive layer thickness that maximizes total areal capacitance was identified as a function of scan rate and confirmed by scaling analysis.« less

Multidimensional Cyclic Voltammetry Simulations of Pseudocapacitive Electrodes with a Conducting Nanorod Scaffold

DOE PAGES

Mei, Bing-Ang; Li, Bin; Lin, Jie; ...

2017-10-27

This paper aims to understand the effect of nanoarchitecture on the performance of pseudocapacitive electrodes consisting of conducting scaffold coated with pseudocapacitive material. To do so, two-dimensional numerical simulations of ordered conducting nanorods coated with a thin film of pseudocapacitive material were performed. The simulations reproduced three-electrode cyclic voltammetry measurements based on a continuum model derived from first principles. Two empirical approaches commonly used experimentally to characterize the contributions of surface-controlled and diffusion-controlled charge storage mechanisms to the total current density with respect to scan rate were theoretically validated for the first time. Moreover, the areal capacitive capacitance, attributed tomore » EDL formation, remained constant and independent of electrode dimensions, at low scan rates. However, at high scan rates, it decreased with decreasing conducting nanorod radius and increasing pseudocapacitive layer thickness due to resistive losses. By contrast, the gravimetric faradaic capacitance, due to reversible faradaic reactions, decreased continuously with increasing scan rate and pseudocapacitive layer thickness but was independent of conducting nanorod radius. Note that the total gravimetric capacitance predicted numerically featured values comparable to experimental measurements. Finally, an optimum pseudocapacitive layer thickness that maximizes total areal capacitance was identified as a function of scan rate and confirmed by scaling analysis.« less

Flexible Lithium-Ion Batteries with High Areal Capacity Enabled by Smart Conductive Textiles.

PubMed

Ha, Sung Hoon; Shin, Kyu Hang; Park, Hae Won; Lee, Yun Jung

2018-02-05

Increasing demand for flexible devices in various applications, such as smart watches, healthcare, and military applications, requires the development of flexible energy-storage devices, such as lithium-ion batteries (LIBs) with high flexibility and capacity. However, it is difficult to ensure high capacity and high flexibility simultaneously through conventional electrode preparation processes. Herein, smart conductive textiles are employed as current collectors for flexible LIBs owing to their inherent flexibility, fibrous network, rough surface for better adhesion, and electrical conductivity. Conductivity and flexibility are further enhanced by nanosizing lithium titanate oxide (LTO) and lithium iron phosphate (LFP) active materials, and hybridizing them with a flexible 2D graphene template. The resulting LTO/LFP full cells demonstrate high areal capacity and flexibility with tolerance to mechanical fatigue. The battery achieves a capacity of 1.2 mA h cm -2 while showing excellent flexibility. The cells demonstrate stable open circuit voltage retention under repeated flexing for 1000 times at a bending radius of 10 mm. The discharge capacity of the unflexed battery is retained in cells subjected to bending for 100 times at bending radii of 30, 20, and 10 mm, respectively, confirming that the suggested electrode configuration successfully prevents structural damage (delamination or cracking) upon repeated deformation. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preliminary evaluation of ground-water flow in Bear Creek Valley, the Oak Ridge Reservation, Tennessee

USGS Publications Warehouse

Bailey, Z.C.

1988-01-01

Bear Creek Valley, Tennessee contains hazardous waste disposal sites where contaminants leach into ground and surface water. Groundwater flow and the potential migration of contaminants is poorly understood. The Valley is underlain by calcareous shale that contains limestone units. Ridges to the north and south are underlain by interbedded sandstones, siltstone and shale, and by massive, siliceous dolomite, respectively. The bedrock, which dips about 45 degrees southeast, is overlain by regolith to a maximum thickness of 80 ft. Observed hydraulic conductivities for the regolith range from 0.01 to 13 ft/day, and for the bedrock, from 0.001 to 11 ft/day. Groundwater flow is probably toward streams and is preferential along strike because of an areal anisotropy in hydraulic conductivity. A cross sectional groundwater flow model was used to test the conceptualized flow system and to help identify areas where additional data are needed. The preliminary model shows a pattern of recharge at both ridges, flow toward the valley, and upward flow that discharges into Bear Creek. Final model values of hydraulic conductivity in the bedrock range from 0.01 to 0.1 ft/day and reflect an areal anisotropy ratio of 1:5. Simulated recharge was 10 inches/year. (USGS)

Application of atmospheric-pressure plasma jet processed carbon nanotubes to liquid and quasi-solid-state gel electrolyte supercapacitors

NASA Astrophysics Data System (ADS)

Kuok, Fei-Hong; Kan, Ken-Yuan; Yu, Ing-Song; Chen, Chieh-Wen; Hsu, Cheng-Che; Cheng, I.-Chun; Chen, Jian-Zhang

2017-12-01

We use a dc-pulse nitrogen atmospheric-pressure plasma jet (APPJ) to calcine carbon nanotubes (CNTs) pastes that are screen-printed on carbon cloth. 30-s APPJ treatment can efficiently oxidize and vaporize the organic binders, thereby forming porous structures. As indicated by X-ray photoelectron spectroscopy (XPS) and electron probe microanalysis (EPMA), the oxygen content decreases after APPJ treatment owing to the oxidation and vaporization of ethyl cellulose, terpineol, and ethanol. Nitrogen doping was introduced to the materials by the nitrogen APPJ. APPJ-calcination improves the wettability of the CNTs printed on carbon cloth, as evidenced by water contact angle measurement. Raman spectroscopy indicates that reactive species of nitrogen APPJ react violently with CNTs in only 30-s APPJ processing time and introduce defects and/or surface functional groups on CNTs. Carbon cloths with calcined CNT layers are used as electrodes for liquid and quasi-solid-state electrolyte supercapacitors. Under a cyclic voltammetry test with a 2 mV/s potential scan rate, the specific capacitance is 73.84 F/g (areal capacitance = 5.89 mF/cm2) with a 2 M KCl electrolyte and 66.47 F/g (areal capacitance = 6.10 mF/cm2) with a H2SO4/polyvinyl alcohol (PVA) gel electrolyte.

Estimation of Rainfall Sampling Uncertainty: A Comparison of Two Diverse Approaches

NASA Technical Reports Server (NTRS)

Steiner, Matthias; Zhang, Yu; Baeck, Mary Lynn; Wood, Eric F.; Smith, James A.; Bell, Thomas L.; Lau, William K. M. (Technical Monitor)

2002-01-01

The spatial and temporal intermittence of rainfall causes the averages of satellite observations of rain rate to differ from the "true" average rain rate over any given area and time period, even if the satellite observations are perfectly accurate. The difference of satellite averages based on occasional observation by satellite systems and the continuous-time average of rain rate is referred to as sampling error. In this study, rms sampling error estimates are obtained for average rain rates over boxes 100 km, 200 km, and 500 km on a side, for averaging periods of 1 day, 5 days, and 30 days. The study uses a multi-year, merged radar data product provided by Weather Services International Corp. at a resolution of 2 km in space and 15 min in time, over an area of the central U.S. extending from 35N to 45N in latitude and 100W to 80W in longitude. The intervals between satellite observations are assumed to be equal, and similar In size to what present and future satellite systems are able to provide (from 1 h to 12 h). The sampling error estimates are obtained using a resampling method called "resampling by shifts," and are compared to sampling error estimates proposed by Bell based on earlier work by Laughlin. The resampling estimates are found to scale with areal size and time period as the theory predicts. The dependence on average rain rate and time interval between observations is also similar to what the simple theory suggests.

Benthic flux of dissolved nickel into the water column of south San Francisco Bay

USGS Publications Warehouse

Topping, B.R.; Kuwabara, J.S.; Parcheso, Francis; Hager, S.W.; Arnsberg, A.J.; Murphy, Fred

2001-01-01

Field and laboratory studies were conducted between April, 1998 and May, 1999 to provide the first direct measurements of the benthic flux of dissolved (0.2-micron filtered) nickel between the bottom sediment and water column at three sites in the southern component of San Francisco Bay (South Bay), California. Dissolved nickel and predominant ligands (represented by dissolved organic carbon, and sulfides) were the solutes of primary interest, although a variety of ancillary measurements were also performed to provide a framework for interpretation. Results described herein integrate information needs identified by the State Water Resources Control Board and local stakeholders with fundamental research associated with the U.S. Geological Survey Toxic Substances Hydrology Program. Dissolved-Ni concentrations in the bottom water over the three sampling dates ranged from 34 to 43 nanomoles per liter. Dissolved-macronutrient concentrations in the bottom water were consistently higher (frequently by orders of magnitude) than surface-water determinations reported for similar times and locations (Regional Monitoring Program, 2001). This is consistent with measured positive benthic fluxes for the macronutrients. Benthic-flux estimates for dissolved nickel from core-incubations, when areally averaged over the South Bay, were significant (that is, of equivalent or greater order of magnitude) relative to previously reported freshwater point and non-point sources. This observation is consistent with previous determinations for other metals, and with the potential remobilization of sediment-associated metals that have been ubiquitously distributed in the South Bay. Similar to dissolved-nickel results, benthic flux of macronutrients was also consistently significant relative to surface-water inputs. These results add to a growing body of knowledge that strongly suggests a need to consider contaminant transport across the sediment-water interface when establishing future management strategies for the watershed.

Global color variations on the Martian surface

USGS Publications Warehouse

Soderblom, L.A.; Edwards, K.; Eliason, E.M.; Sanchez, E.M.; Charette, M.P.

1978-01-01

Surface materials exposed throughout the equatorial region of Mars have been classified and mapped on the basis of spectral reflectance properties determined by the Viking II Orbiter vidicon cameras. Frames acquired at each of three wavelengths (0.45 ?? 0.03 ??m, 0.53 ?? 0.05 ??m, and 0.59 ?? 0.05 ??m) during the approach of Viking Orbiter II in Martian summer (Ls = 105??) were mosaicked by computer. The mosaics cover latitudes 30??N to 63??S for 360?? of longitude and have resolutions between 10 and 20 km per line pair. Image processing included Mercator transformation and removal of an average Martian photometric function to produce albedo maps at three wavelengths. The classical dark region between the equator and ???30??S in the Martian highlands is composed of two units: (i) and ancient unit consisting of topographic highs (ridges, crater rims, and rugged plateaus riddled with small dendritic channels) which is among the reddest on the planet (0.59/0.45 ??m {reversed tilde equals} 3); and (ii) intermediate age, smooth, intercrater volcanic plains displaying numerous mare ridges which are among the least red on Mars (0.59/0.45 ??m {reversed tilde equals} 2). The relatively young shield volcanoes are, like the oldest unit, dark and very red. Two probable eolian deposits are recognized in the intermediate and high albedo regions. The stratigraphically lower unit is intermediate in both color (0.59/ 0.45 ??m {reversed tilde equals} 2.5) and albedo. The upper unit has the highest albedo, is very red (0.59/0.45 ??m {reversed tilde equals} 3), and is apparently the major constituent of the annual dust storms as its areal extent changes from year to year. The south polar ice cap and condensate clouds dominate the southernmost part of the mosaics. ?? 1978.

A space imaging concept based on a 4m structured spun-cast borosilicate monolithic primary mirror

NASA Astrophysics Data System (ADS)

West, S. C.; Bailey, S. H.; Bauman, S.; Cuerden, B.; Granger, Z.; Olbert, B. H.

2010-07-01

Lockheed Martin Corporation (LMC) tasked The University of Arizona Steward Observatory (UASO) to conduct an engineering study to examine the feasibility of creating a 4m space telescope based on mature borosilicate technology developed at the UASO for ground-based telescopes. UASO has completed this study and concluded that existing launch vehicles can deliver a 4m monolithic telescope system to a 500 km circular orbit and provide reliable imagery at NIIRS 7-8. An analysis of such an imager based on a lightweight, high-performance, structured 4m primary mirror cast from borosilicate glass is described. The relatively high CTE of this glass is used to advantage by maintaining mirror shape quality with a thermal figuring method. Placed in a 290 K thermal shroud (similar to the Hubble Space Telescope), the orbit averaged figure surface error is 6nm rms when earth-looking. Space-looking optical performance shows that a similar thermal conditioning scheme combined with a 270 K shroud achieves primary mirror distortion of 10 nm rms surface. Analysis shows that a 3-point bipod mount will provide launch survivability with ample margin. The primary mirror naturally maintains its shape at 1g allowing excellent end-to-end pre-launch testing with e.g. the LOTIS 6.5m Collimator. The telescope includes simple systems to measure and correct mirror shape and alignment errors incorporating technologies already proven on the LOTIS Collimator. We have sketched a notional earth-looking 4m telescope concept combined with a wide field TMA concept into a DELTA IV or ATLAS 552 EELV fairing. We have combined an initial analysis of launch and space performance of a special light-weighted honeycomb borosilicate mirror (areal density 95 kg/m2) with public domain information on the existing launch vehicles.

Kelp-derived three-dimensional hierarchical porous N, O-doped carbon for flexible solid-state symmetrical supercapacitors with excellent performance

NASA Astrophysics Data System (ADS)

Zhang, Yifu; Jiang, Hanmei; Wang, Qiushi; Zheng, Jiqi; Meng, Changgong

2018-07-01

Three-dimensional (3D) porous N, O-doped carbon with hierarchical structures composed of micropores, mesopores and macropores were synthesized by the direct carbonization of kelp with a "self-activation" process. The as-obtained 3D N, O-doped carbon remained abundant N and O functional groups and the BET specific surface area measured 656 m2 g-1. 3D hierarchical porous structures with the pore size ranged from several nanometers to hundred nanometers and lots of pores were attributed to mesopores with the average pore size of about 5.4 nm. Electrochemical properties of the 3D hierarchical porous N, O-doped carbon as a supercapactior (SC) electrode were investigated and it delivered excellent capacitance of 669 mF cm-2 at 1 mA cm-2 due to its 3D hierarchical porous structures with high specific surface area which is beneficial for improving ionic storage and transportation in electrodes. This kelp-derived carbon exhibited excellent cyclic performance with the retention of 104% after 10,000 cycles. A flexible solid-state symmetric SC (SSC) device was fabricated using the 3D hierarchical porous N, O-doped carbon and delivered an excellent capacitance of 412 mF cm-2 at 2 mA cm-2 and satisfying cyclic stability with the retention of 85% after 10,000 cycles. The areal energy density of the SSC device reach up to 0.146 mWh cm-2 at the power density of 0.8 mW cm-2. This facile route for low-cost carbonaceous materials with novel architecture and functionality can be as a promising alternative to synthesize biomass carbon for practical SC application.

Space reflector technology and its system implications

NASA Technical Reports Server (NTRS)

Billman, K. W.; Gilbreath, W. P.; Bowen, S. W.

1979-01-01

The technical feasibility of providing nearly continuous solar energy to a world-distributed set of conversion sites by means of a system of orbiting, large-area, low-areal-density reflecting structures is examined. Requisite mirror area to provide a chosen, year-averaged site intensity is shown. A modeled reflector structure, with suitable planarity and ability to meet operational torques and loads, is discussed. Typical spatial and temporal insolation profiles are presented. These determine the sizing of components and the output electric power from a baselined photovoltaic conversion system. Technical and economic challenges which, if met, would allow the system to provide a large fraction of future world energy needs at costs competitive to circa-1995 fossil and nuclear sources are discussed.

Software for roof defects recognition on aerial photographs

NASA Astrophysics Data System (ADS)

Yudin, D.; Naumov, A.; Dolzhenko, A.; Patrakova, E.

2018-05-01

The article presents information on software for roof defects recognition on aerial photographs, made with air drones. An areal image segmentation mechanism is described. It allows detecting roof defects – unsmoothness that causes water stagnation after rain. It is shown that HSV-transformation approach allows quick detection of stagnation areas, their size and perimeters, but is sensitive to shadows and changes of the roofing-types. Deep Fully Convolutional Network software solution eliminates this drawback. The tested data set consists of the roofing photos with defects and binary masks for them. FCN approach gave acceptable results of image segmentation in Dice metric average value. This software can be used in inspection automation of roof conditions in the production sector and housing and utilities infrastructure.

Assessing the present and future probability of Hurricane Harvey's rainfall.

PubMed

Emanuel, Kerry

2017-11-28

We estimate, for current and future climates, the annual probability of areally averaged hurricane rain of Hurricane Harvey's magnitude by downscaling large numbers of tropical cyclones from three climate reanalyses and six climate models. For the state of Texas, we estimate that the annual probability of 500 mm of area-integrated rainfall was about 1% in the period 1981-2000 and will increase to 18% over the period 2081-2100 under Intergovernmental Panel on Climate Change (IPCC) AR5 representative concentration pathway 8.5. If the frequency of such event is increasingly linearly between these two periods, then in 2017 the annual probability would be 6%, a sixfold increase since the late 20th century. Copyright © 2017 the Author(s). Published by PNAS.

Parabolic features and the erosion rate on Venus

NASA Technical Reports Server (NTRS)

Strom, Robert G.

1993-01-01

The impact cratering record on Venus consists of 919 craters covering 98 percent of the surface. These craters are remarkably well preserved, and most show pristine structures including fresh ejecta blankets. Only 35 craters (3.8 percent) have had their ejecta blankets embayed by lava and most of these occur in the Atla-Beta Regio region; an area thought to be recently active. parabolic features are associated with 66 of the 919 craters. These craters range in size from 6 to 105 km diameter. The parabolic features are thought to be the result of the deposition of fine-grained ejecta by winds in the dense venusian atmosphere. The deposits cover about 9 percent of the surface and none appear to be embayed by younger volcanic materials. However, there appears to be a paucity of these deposits in the Atla-Beta Regio region, and this may be due to the more recent volcanism in this area of Venus. Since parabolic features are probably fine-grain, wind-deposited ejecta, then all impact craters on Venus probably had these deposits at some time in the past. The older deposits have probably been either eroded or buried by eolian processes. Therefore, the present population of these features is probably associated with the most recent impact craters on the planet. Furthermore, the size/frequency distribution of craters with parabolic features is virtually identical to that of the total crater population. This suggests that there has been little loss of small parabolic features compared to large ones, otherwise there should be a significant and systematic paucity of craters with parabolic features with decreasing size compared to the total crater population. Whatever is erasing the parabolic features apparently does so uniformly regardless of the areal extent of the deposit. The lifetime of parabolic features and the eolian erosion rate on Venus can be estimated from the average age of the surface and the present population of parabolic features.

Large Areal Mass, Mechanically Tough and Freestanding Electrode Based on Heteroatom-doped Carbon Nanofibers for Flexible Supercapacitors.

PubMed

Liu, Rong; Ma, Lina; Mei, Jia; Huang, Shu; Yang, Shaoqiang; Li, Enyuan; Yuan, Guohui

2017-02-21

A flexible and freestanding supercapacitor electrode with a N,P-co-doped carbon nanofiber network (N,P-CNFs)/graphene (GN) composite loaded on bacterial cellulose (BC) is first designed and fabricated in a simple, low-cost, and effective approach. The porous structure and excellent mechanical properties make the BC paper an ideal substrate that shows a large areal mass of 8 mg cm -2 . As a result, the flexible N,P-CNFs/GN/BC paper electrode shows appreciable areal capacitance (1990 mF cm -2 in KOH and 2588 mF cm -2 in H 2 SO 4 electrolytes) without sacrificing gravimetric capacitance (248.8 F g -1 and 323.5 F g -1 ), exhibits excellent cycling ability (without capacity loss after 20 000 cycles), and remarkable tensile strength (42.8 MPa). By direct coupling of two membrane electrodes, the symmetric supercapacitor delivers a prominent areal capacitance of 690 mF cm -2 in KOH and 898 mF cm -2 in H 2 SO 4 , and remarkable power/energy density (19.98 mW cm -2 /0.096 mW h cm -2 in KOH and 35.01 mW cm -2 /0.244 mW h cm -2 in H 2 SO 4 ). Additionally, it shows stable behavior in both bent and flat states. These results promote new opportunities for N,P-CNFs/GN/BC paper electrodes as high areal performance, freestanding electrodes for flexible supercapacitors. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

ABCD: Anthropometry, Body Composition, and Crohn Disease.

PubMed

Brookes, Denise S K; Briody, Julie N; Davies, Peter S W; Hill, Rebecca J

2016-07-01

Young individuals with Crohn disease (CD) are at risk of poor bone mineral density (BMD) and reduced lean tissue mass (LTM). The importance of LTM for maintaining skeletal health, in both incident and established CD, is evidenced. We used dual-energy x-ray absorptiometry assessment to identify areal BMD and LTM in individuals with CD. In 57 patients with CD (15F; 12.99-14.16 years) anthropometric, disease activity, bone age assessment, and total body dual-energy x-ray absorptiometry measurements were acquired. A 4-step algorithm was used to assess simultaneous bone and body composition data: areal BMD and height z scores, and LTM for height and bone mineral content (BMC) for LTM z scores were calculated. Low z score cut-off values were defined as ≤1 standard deviations below the population means. The CD cohort showed: low areal BMD z scores (P = 0.00); and low LTM for height (P = 0.00) according to defined cut-off values. BMC appeared to be adapting for the lower amount of LTM. Correcting for bone age eliminated the low areal BMD z scores. As expected, LTM for height and BMC for LTM z scores remained unchanged. We present a useful clinical algorithm to show significant LTM for height deficits, regardless of chronological or bone age, in this CD cohort. BMC seemed to adapt to the reduced LTM, indicating clinically "normal" areal BMD for age when considered for height. The ongoing deficits in LTM may, however, create chronic long-term consequences for bone health. Improving LTM should be a focus of clinical treatment in individuals with CD.

Reliable Quantitative Mineral Abundances of the Martian Surface using THEMIS

NASA Astrophysics Data System (ADS)

Smith, R. J.; Huang, J.; Ryan, A. J.; Christensen, P. R.

2013-12-01

The following presents a proof of concept that given quality data, Thermal Emission Imaging System (THEMIS) data can be used to derive reliable quantitative mineral abundances of the Martian surface using a limited mineral library. The THEMIS instrument aboard the Mars Odyssey spacecraft is a multispectral thermal infrared imager with a spatial resolution of 100 m/pixel. The relatively high spatial resolution along with global coverage makes THEMIS datasets powerful tools for comprehensive fine scale petrologic analyses. However, the spectral resolution of THEMIS is limited to 8 surface sensitive bands between 6.8 and 14.0 μm with an average bandwidth of ~ 1 μm, which complicates atmosphere-surface separation and spectral analysis. This study utilizes the atmospheric correction methods of both Bandfield et al. [2004] and Ryan et al. [2013] joined with the iterative linear deconvolution technique pioneered by Huang et al. [in review] in order to derive fine-scale quantitative mineral abundances of the Martian surface. In general, it can be assumed that surface emissivity combines in a linear fashion in the thermal infrared (TIR) wavelengths such that the emitted energy is proportional to the areal percentage of the minerals present. TIR spectra are unmixed using a set of linear equations involving an endmember library of lab measured mineral spectra. The number of endmembers allowed in a spectral library are restricted to a quantity of n-1 (where n = the number of spectral bands of an instrument), preserving one band for blackbody. Spectral analysis of THEMIS data is thus allowed only seven endmembers. This study attempts to prove that this limitation does not prohibit the derivation of meaningful spectral analyses from THEMIS data. Our study selects THEMIS stamps from a region of Mars that is well characterized in the TIR by the higher spectral resolution, lower spatial resolution Thermal Emission Spectrometer (TES) instrument (143 bands at 10 cm-1 sampling and 3x5 km pixel). Multiple atmospheric corrections are performed for one image using the methods of Bandfield et al. [2004] and Ryan et al. [2013]. 7x7 pixel areas were selected, averaged, and compared using each atmospherically corrected image to ensure consistency. Corrections that provided reliable data were then used for spectral analyses. Linear deconvolution is performed using an iterative spectral analysis method [Huang et al. in review] that takes an endmember spectral library, and creates mineral combinations based on prescribed mineral group selections. The script then performs a spectral mixture analysis on each surface spectrum using all possible mineral combinations, and reports the best modeled fit to the measured spectrum. Here we present initial results from Syrtis Planum where multiple atmospherically corrected THEMIS images were deconvolved to produce similar spectral analysis results, within the detection limit of the instrument. THEMIS mineral abundances are comparable to TES-derived abundances. References: Bandfield, JL et al. [2004], JGR 109, E10008 Huang, J et al., JGR, in review Ryan, AJ et al. [2013], AGU Fall Meeting

UAV-based remote sensing of the Heumoes landslide, Austria Vorarlberg

NASA Astrophysics Data System (ADS)

Niethammer, U.; Joswig, M.

2009-04-01

The Heumoes landslide, is located in the eastern Vorarlberg Alps, Austria, 10 km southeast of Dornbirn. The extension of the landslide is about 2000 m in west to east direction and about 500 m at its widest extent in north to south direction. It occurs between an elevation of 940 m in the east and 1360 m in the west, slope angles of more than 60 % can be observed as well as almost flat areas. Its total volume is estimated to be 9.400.000 cubic meters and its average velocities amount to some centimeter per year. Surface signatures or 'photolineations' of creeping landslides, e.g. fractures and rupture lines in sediments and street pavings, and vegetation contrasts by changes of water table in shallow vegetation in principle can be resolved by remote sensing. The necessary ground cell resolution of few centimeters, however, generally can't be achieved by routine areal or satellite imagery. The fast technological progress of unmanned areal vehicles (UAV) and the reduced payload by miniaturized optical cameras now allow for UAV remote sensing applications that are below the high financial limits of military intelligence. Even with 'low-cost' equipment, the necessary centimeter-scale ground cell resolution can be achieved by adapting the flight altitude to some ten to one hundred meters. Operated by scientists experienced in remote-control flight models, UAV remote sensing can now be performed routinely, and campaign-wise after any significant event of, e.g., heavy rainfall, or partial mudflow. We have investigated a concept of UAV-borne remote sensing based on motorized gliders, and four-propeller helicopters or 'quad-rotors'. Several missions were flown over the Heumoes landslide. Between 2006 and 2008 three series UAV-borne photographs of the Heumoes landslide were taken and could be combined to orto-mosaics of the slope area within few centimeters ground cell resolution. We will present the concept of our low cost quad-rotor UAV system and first results of the image-processing based evaluation of the acquired images to characterize spatial and temporal details of landslide behaviour. We will also sketch first schemes of joint interpretation or 'data fusion' of UAV-based remote sensing with the results from geophysical mapping of underground distribution of soil moisture and fracture processes (Walter & Joswig, EGU 2009).

Comparative study of diode-pumped alkali vapor laser and exciplex-pumped alkali laser systems and selection principal of parameters

NASA Astrophysics Data System (ADS)

Huang, Wei; Tan, Rongqing; Li, Zhiyong; Han, Gaoce; Li, Hui

2017-03-01

A theoretical model based on common pump structure is proposed to analyze the output characteristics of a diode-pumped alkali vapor laser (DPAL) and XPAL (exciplex-pumped alkali laser). Cs-DPAL and Cs-Ar XPAL systems are used as examples. The model predicts that an optical-to-optical efficiency approaching 80% can be achieved for continuous-wave four- and five-level XPAL systems with broadband pumping, which is several times the pumped linewidth for DPAL. Operation parameters including pumped intensity, temperature, cell's length, mixed gas concentration, pumped linewidth, and output coupler are analyzed for DPAL and XPAL systems based on the kinetic model. In addition, the predictions of selection principal of temperature and cell's length are also presented. The concept of the equivalent "alkali areal density" is proposed. The result shows that the output characteristics with the same alkali areal density but different temperatures turn out to be equal for either the DPAL or the XPAL system. It is the areal density that reflects the potential of DPAL or XPAL systems directly. A more detailed analysis of similar influences of cavity parameters with the same areal density is also presented.

3D MnO2-graphene composites with large areal capacitance for high-performance asymmetric supercapacitors.

PubMed

Zhai, Teng; Wang, Fuxin; Yu, Minghao; Xie, Shilei; Liang, Chaolun; Li, Cheng; Xiao, Fangming; Tang, Renheng; Wu, Qixiu; Lu, Xihong; Tong, Yexiang

2013-08-07

In this paper, we reported an effective and simple strategy to prepare large areal mass loading of MnO2 on porous graphene gel/Ni foam (denoted as MnO2/G-gel/NF) for supercapacitors (SCs). The MnO2/G-gel/NF (MnO2 mass: 13.6 mg cm(-2)) delivered a large areal capacitance of 3.18 F cm(-2) (234.2 F g(-1)) and good rate capability. The prominent electrochemical properties of MnO2/G-gel/NF are attributed to the enhanced conductivities and improved accessible area for ions in electrolytes. Moreover, an asymmetric supercapacitor (ASC) based on MnO2/G-gel/NF (MnO2 mass: 6.1 mg cm(-2)) as the positive electrode and G-gel/NF as the negative electrode achieved a remarkable energy density of 0.72 mW h cm(-3). Additionally, the fabricated ASC device also exhibited excellent cycling stability, with less than 1.5% decay after 10,000 cycles. The ability to effectively develop SC electrodes with high mass loading should open up new opportunities for SCs with high areal capacitance and high energy density.

On the derivation of the areal reduction factor of storms

NASA Astrophysics Data System (ADS)

Bacchi, Baldassare; Ranzi, Roberto

A stochastic derivation of the areal reduction factor (ARF) of the storm intensity is presented: it is based on the analysis of the crossing properties of the rainfall process aggregated in space and time. As a working hypothesis, the number of crossings of high rainfall intensity levels is assumed to be Poisson-distributed and a hyperbolic tail of the probability of exceedances of rainfall intensity has been adopted. These hypotheses are supported by the analysis of radar maps during an intense storm event which occurred in Northern Italy. The reduction factor derived from this analysis shows a power-law decay with respect to the area of integration and the duration of the storm. The areal reduction results as a function of the storm duration and of its frequency. A weak, but significant decrease of the areal reduction factor with respect to the return period is shown by the functions derived, and this result is consistent with that of some recent studies on this topic. The results derived, although preliminary, may find useful applications for the definition of the design storm in urban catchments of a size greater than some square kilometres and with duration of some hours.

2D reentrant auxetic structures of graphene/CNT networks for omnidirectionally stretchable supercapacitors.

PubMed

Kim, Byoung Soo; Lee, Kangsuk; Kang, Seulki; Lee, Soyeon; Pyo, Jun Beom; Choi, In Suk; Char, Kookheon; Park, Jong Hyuk; Lee, Sang-Soo; Lee, Jonghwi; Son, Jeong Gon

2017-09-14

Stretchable energy storage systems are essential for the realization of implantable and epidermal electronics. However, high-performance stretchable supercapacitors have received less attention because currently available processing techniques and material structures are too limited to overcome the trade-off relationship among electrical conductivity, ion-accessible surface area, and stretchability of electrodes. Herein, we introduce novel 2D reentrant cellular structures of porous graphene/CNT networks for omnidirectionally stretchable supercapacitor electrodes. Reentrant structures, with inwardly protruded frameworks in porous networks, were fabricated by the radial compression of vertically aligned honeycomb-like rGO/CNT networks, which were prepared by a directional crystallization method. Unlike typical porous graphene structures, the reentrant structure provided structure-assisted stretchability, such as accordion and origami structures, to otherwise unstretchable materials. The 2D reentrant structures of graphene/CNT networks maintained excellent electrical conductivities under biaxial stretching conditions and showed a slightly negative or near-zero Poisson's ratio over a wide strain range because of their structural uniqueness. For practical applications, we fabricated all-solid-state supercapacitors based on 2D auxetic structures. A radial compression process up to 1/10 th densified the electrode, significantly increasing the areal and volumetric capacitances of the electrodes. Additionally, vertically aligned graphene/CNT networks provided a plentiful surface area and induced sufficient ion transport pathways for the electrodes. Therefore, they exhibited high gravimetric and areal capacitance values of 152.4 F g -1 and 2.9 F cm -2 , respectively, and had an excellent retention ratio of 88% under a biaxial strain of 100%. Auxetic cellular and vertically aligned structures provide a new strategy for the preparation of robust platforms for stretchable energy storage electrodes.

Adhesion at Entangled Polymer Interfaces: A Unified Approach..

NASA Astrophysics Data System (ADS)

Wool, Richard

2006-03-01

A unified theory of fracture of polymer interfaces was developed which was based on the Rigidity Percolation model of fracture [R.P. Wool, J.Polym.Sci. Part A: Polym Phys., 43,168(2005)]. The polymer fractured critically when the normalized entanglement density p, approached the percolation threshold pc. The fracture energy was found to be G1c ˜ [p-pc]. When applied to interfaces of width X, containing an areal density σ of chains, each contributing L chain entanglements, the percolation term p ˜ σL/X and the percolation threshold was related to σc, Lc, or Xc. For welding of A/A symmetric interfaces, p = σL/X, and pc Lc/M 0, such that when σ/X ˜1/M for randomly distributed chain ends, p˜L ˜ (t/M)^1/2, G/G* = (t/τ*)^1/2, where the weld time τ* ˜ M. When the chain ends are segregated to the surface, σ is constant with time and G/G* = [t/τ*]^1/4. For sub-Tg welding, there exists a surface mobile layer (due to the critical Lindemann Atom fraction) of depth X ˜ 1/δT^ν such that G ˜ δT-2ν, where the critical exponent v = 0.8. For incompatible A/B interfaces of Helfand width d, normalized width w = d/Rge, and entanglement density Nent ˜ d/Le, p ˜ d such that, G1c ˜ [d-dc], G1c ˜ [w-1], and G ˜ [Nent-Nc]. For incompatible A/B interfaces reinforced by an areal density σ of compatibilizer chains, L and X are constant, p ˜ σ, pc ˜σc, such that G1c ˜ [σ-σc], which is in excellent agreement with experimental data.

Nanolaminate Mirrors With "Piston" Figure-Control Actuators

NASA Technical Reports Server (NTRS)

Lowman, Andrew; Redding, David; Hickey, Gregory; Knight, Jennifer; Moynihan, Philip; Lih, Shyh0Shiuh; Barbee, Troy

2003-01-01

Efforts are under way to develop a special class of thin-shell curved mirrors for high-resolution imaging in visible and infrared light in a variety of terrestrial or extraterrestrial applications. These mirrors can have diameters of the order of a meter and include metallic film reflectors on nanolaminate substrates supported by multiple distributed piezoceramic gpiston h-type actuators for micron-level figure control. Whereas conventional glass mirrors of equivalent size and precision have areal mass densities between 50 and 150 kg/sq m, the nanolaminate mirrors, including not only the reflector/ shell portions but also the actuators and the backing structures needed to react the actuation forces, would have areal mass densities that may approach .5 kg/m2. Moreover, whereas fabrication of a conventional glass mirror of equivalent precision takes several years, the reflector/shell portion of a nanolaminate mirror can be fabricated in less than a week, and its actuation system can be fabricated in 1 to 2 months. The engineering of these mirrors involves a fusion of the technological heritage of multisegmented adaptive optics and deformable mirrors with more recent advances in metallic nanolaminates and in mathematical modeling of the deflections of thin, curved shells in response to displacements by multiple, distributed actuators. Because a nanolaminate shell is of the order of 10 times as strong as an otherwise identical shell made of a single, high-strength, non-nanolaminate metal suitable for mirror use, a nanolaminate mirror can be made very thin (typically between 100 and 150 m from the back of the nanolaminate substrate to the front reflecting surface). The thinness and strength of the nanolaminate are what make it possible to use distributed gpiston h-type actuators for surface figure control with minimal local concentrated distortion (called print-through in the art) at the actuation points.

Nonfouling NTA-PEG-Based TEM Grid Coatings for Selective Capture of Histidine-Tagged Protein Targets from Cell Lysates.

PubMed

Benjamin, Christopher J; Wright, Kyle J; Hyun, Seok-Hee; Krynski, Kyle; Yu, Guimei; Bajaj, Ruchika; Guo, Fei; Stauffacher, Cynthia V; Jiang, Wen; Thompson, David H

2016-01-19

We report the preparation and performance of TEM grids bearing stabilized nonfouling lipid monolayer coatings. These films contain NTA capture ligands of controllable areal density at the distal end of a flexible poly(ethylene glycol) 2000 (PEG2000) spacer to avoid preferred orientation of surface-bound histidine-tagged (His-tag) protein targets. Langmuir-Schaefer deposition at 30 mN/m of mixed monolayers containing two novel synthetic lipids-1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[(5-amido-1-carboxypentyl)iminodiacetic acid]polyethylene glycolamide 2000) (NTA-PEG2000-DSPE) and 1,2-(tricosa-10',12'-diynoyl)-sn-glycero-3-phosphoethanolamine-N-(methoxypolyethylene glycolamide 350) (mPEG350-DTPE)-in 1:99 and 5:95 molar ratios prior to treatment with a 5 min, 254 nm light exposure was used for grid fabrication. These conditions were designed to limit nonspecific protein adsorption onto the stabilized lipid coating by favoring the formation of a mPEG350 brush layer below a flexible, mushroom conformation of NTA-PEG2000 at low surface density to enable specific immobilization and random orientation of the protein target on the EM grid. These grids were then used to capture His6-T7 bacteriophage and RplL from cell lysates, as well as purified His8-green fluorescent protein (GFP) and nanodisc solubilized maltose transporter, His6-MalFGK2. Our findings indicate that TEM grid supported, polymerized NTA lipid monolayers are capable of capturing His-tag protein targets in a manner that controls their areal densities, while efficiently blocking nonspecific adsorption and limiting film degradation, even upon prolonged detergent exposure.

Thin film growth into the ion track structures in polyimide by atomic layer deposition

NASA Astrophysics Data System (ADS)

Mättö, L.; Malm, J.; Arstila, K.; Sajavaara, T.

2017-09-01

High-aspect ratio porous structures with controllable pore diameters and without a stiff substrate can be fabricated using the ion track technique. Atomic layer deposition is an ideal technique for depositing thin films and functional surfaces on complicated 3D structures due to the high conformality of the films. In this work, we studied Al2O3 and TiO2 films grown by ALD on pristine polyimide (Kapton HN) membranes as well as polyimide membranes etched in sodium hypochlorite (NaOCl) and boric acid (BO3) solution by means of RBS, PIXE, SEM-EDX and helium ion microcopy (HIM). The focus was on the first ALD growth cycles. The areal density of Al2O3 film in the 400 cycle sample was determined to be 51 ± 3 × 1016 at./cm2, corresponding to the thickness of 55 ± 3 nm. Furthermore, the growth per cycle was 1.4 Å/cycle. The growth is highly linear from the first cycles. In the case of TiO2, the growth per cycle is clearly slower during the first 200 cycles but then it increases significantly. The growth rate based on RBS measurements is 0.24 Å/cycle from 3 to 200 cycles and then 0.6 Å/cycle between 200 and 400 cycles. The final areal density of TiO2 film after 400 cycles is 148 ± 3 × 1015 at./cm2 which corresponds to the thickness of 17.4 ± 0.4 nm. The modification of the polyimide surface by etching prior to the deposition did not have an effect on the Al2O3 and TiO2 growth.

2011 Updates on the Long-term Glacier Monitoring Program in Denali National Park and Preserve

NASA Astrophysics Data System (ADS)

Burrows, R. A.; Adema, G. W.; Herreid, S. J.; Arendt, A. A.; Larsen, C. F.

2011-12-01

The area of Denali National Park and Preserve (DENA) dominated by ice is vast, with glaciers covering 3,780 km^2, approximately one sixth of the park's area. They are integral components of the region's hydrologic, ecologic, and geologic systems - with changes to the glacier systems driving the dependent ecosystems. The National Park Service (NPS) conducts long term monitoring of glaciers in Denali with a variety of methods at a range of spatial and temporal scales. This includes seasonal mass balance and surface movement data collection, annual searches for surging glaciers, and decadal areal extent mapping and volume change estimates of all glaciers in the park. If a glacier surge is detected, the event is documented via photography and surface measurements, when possible. In addition, more intensive ground-based GPS surveys of termini and ice surface elevations are conducted on ten study glaciers every 5-10 years, on a rotating basis. Many of the glaciers are located in designated Wilderness, hence the use of mechanized transport is reduced as much as possible. Monitoring objectives are accomplished by park staff and with cooperative agreements with other agencies and universities. Research to understand the context of the long term data is encouraged and supported as much as possible by the NPS and has recently yielded significant results. The year 2011 marks the 20th anniversary of glacier mass balance monitoring on Kahiltna and Traleika Glaciers, located on the south and north sides of Mt. McKinley respectively. A single "index" site near the ELA of each glacier provides an index of winter, summer, and net balances each year as well as flow velocities and changes in surface elevation. Long-term net balance trends are positive from 1991-2003, and negative since 2003, including the 2009-2010 balance year. The average flow velocity at the Kahiltna index site is 200 +/- 21 m/year with a neutral to slightly negative trend, while on Traleika average velocity is 67 +/- 29 m/year with a positive trend. Monitoring glacier behavior and trends using a variety of techniques provides insight to the complexity of glacier change and increases our ability to distinguish local effects from regional and global trends. Parkwide analysis of glacier extent change since the 1950's shows a consistent trend of retreat, except for glaciers that have surged. Longitudinal surface elevation profiling and comparative photography shows relative stability in larger glaciers, but dramatic long-term mass loss on small, relatively low elevation, valley glaciers characteristic of the eastern portion of DENA. These patterns of ice loss are somewhat unique to the Alaska Range and contrast with big losses of ice mass from large glaciers that border the Gulf of Alaska.

Surface texture measurement for additive manufacturing

NASA Astrophysics Data System (ADS)

Triantaphyllou, Andrew; Giusca, Claudiu L.; Macaulay, Gavin D.; Roerig, Felix; Hoebel, Matthias; Leach, Richard K.; Tomita, Ben; Milne, Katherine A.

2015-06-01

The surface texture of additively manufactured metallic surfaces made by powder bed methods is affected by a number of factors, including the powder’s particle size distribution, the effect of the heat source, the thickness of the printed layers, the angle of the surface relative to the horizontal build bed and the effect of any post processing/finishing. The aim of the research reported here is to understand the way these surfaces should be measured in order to characterise them. In published research to date, the surface texture is generally reported as an Ra value, measured across the lay. The appropriateness of this method for such surfaces is investigated here. A preliminary investigation was carried out on two additive manufacturing processes—selective laser melting (SLM) and electron beam melting (EBM)—focusing on the effect of build angle and post processing. The surfaces were measured using both tactile and optical methods and a range of profile and areal parameters were reported. Test coupons were manufactured at four angles relative to the horizontal plane of the powder bed using both SLM and EBM. The effect of lay—caused by the layered nature of the manufacturing process—was investigated, as was the required sample area for optical measurements. The surfaces were also measured before and after grit blasting.

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).

A precipitation regionalization and regime for Iran based on multivariate analysis

NASA Astrophysics Data System (ADS)

Raziei, Tayeb

2018-02-01

Monthly precipitation time series of 155 synoptic stations distributed over Iran, covering 1990-2014 time period, were used to identify areas with different precipitation time variability and regimes utilizing S-mode principal component analysis (PCA) and cluster analysis (CA) preceded by T-mode PCA, respectively. Taking into account the maximum loading values of the rotated components, the first approach revealed five sub-regions characterized by different precipitation time variability, while the second method delineated eight sub-regions featured with different precipitation regimes. The sub-regions identified by the two used methods, although partly overlapping, are different considering their areal extent and complement each other as they are useful for different purposes and applications. Northwestern Iran and the Caspian Sea area were found as the two most distinctive Iranian precipitation sub-regions considering both time variability and precipitation regime since they were well captured with relatively identical areas by the two used approaches. However, the areal extents of the other three sub-regions identified by the first approach were not coincident with the coverage of their counterpart sub-regions defined by the second approach. Results suggest that the precipitation sub-region identified by the two methods would not be necessarily the same, as the first method which accounts for the variance of the data grouped stations with similar temporal variability while the second one which considers a fixed climatology defined by the average over the period 1990-2014 clusters stations having a similar march of monthly precipitation.

Big data managing in a landslide early warning system: experience from a ground-based interferometric radar application

NASA Astrophysics Data System (ADS)

Intrieri, Emanuele; Bardi, Federica; Fanti, Riccardo; Gigli, Giovanni; Fidolini, Francesco; Casagli, Nicola; Costanzo, Sandra; Raffo, Antonio; Di Massa, Giuseppe; Capparelli, Giovanna; Versace, Pasquale

2017-10-01

A big challenge in terms or landslide risk mitigation is represented by increasing the resiliency of society exposed to the risk. Among the possible strategies with which to reach this goal, there is the implementation of early warning systems. This paper describes a procedure to improve early warning activities in areas affected by high landslide risk, such as those classified as critical infrastructures for their central role in society. This research is part of the project LEWIS (Landslides Early Warning Integrated System): An Integrated System for Landslide Monitoring, Early Warning and Risk Mitigation along Lifelines. LEWIS is composed of a susceptibility assessment methodology providing information for single points and areal monitoring systems, a data transmission network and a data collecting and processing center (DCPC), where readings from all monitoring systems and mathematical models converge and which sets the basis for warning and intervention activities. The aim of this paper is to show how logistic issues linked to advanced monitoring techniques, such as big data transfer and storing, can be dealt with compatibly with an early warning system. Therefore, we focus on the interaction between an areal monitoring tool (a ground-based interferometric radar) and the DCPC. By converting complex data into ASCII strings and through appropriate data cropping and average, and by implementing an algorithm for line-of-sight correction, we managed to reduce the data daily output without compromising the capability for performing.

A measurable Lawson criterion and hydro-equivalent curves for inertial confinement fusion

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

Zhou, C. D.; Betti, R.; Departments of Mechanical Engineering and Physics and Astronomy, University of Rochester, Rochester, New York 14623

2008-10-15

It is shown that the ignition condition (Lawson criterion) for inertial confinement fusion (ICF) can be cast in a form dependent on the only two parameters of the compressed fuel assembly that can be measured with existing techniques: the hot spot ion temperature (T{sub i}{sup h}) and the total areal density ({rho}R{sub tot}), which includes the cold shell contribution. A marginal ignition curve is derived in the {rho}R{sub tot}, T{sub i}{sup h} plane and current implosion experiments are compared with the ignition curve. On this plane, hydrodynamic equivalent curves show how a given implosion would perform with respect to themore » ignition condition when scaled up in the laser-driver energy. For 3<{sub n}<6 keV, an approximate form of the ignition condition (typical of laser-driven ICF) is {sub n}{sup 2.6}{center_dot}<{rho}R{sub tot}>{sub n}>50 keV{sup 2.6}{center_dot} g/cm{sup 2}, where <{rho}R{sub tot}>{sub n} and {sub n} are the burn-averaged total areal density and hot spot ion temperature, respectively. Both quantities are calculated without accounting for the alpha-particle energy deposition. Such a criterion can be used to determine how surrogate D{sub 2} and subignited DT target implosions perform with respect to the one-dimensional ignition threshold.« less

Time-resolved Measurements of ICF Capsule Ablator Properties by Streaked X-Ray Radiography

NASA Astrophysics Data System (ADS)

Hicks, Damien

2008-11-01

Determining the capsule ablator thickness and peak laser or x-ray drive pressure required to optimize fuel compression is a critical part of ensuring ICF ignition on the NIF. If too little ablator is burned off, the implosion velocity will be too low for adequate final compression; if too much ablator is burned off, the fuel will be preheated or the shell will be broken up by growth of hydrodynamic instabilities, again compromising compression. Avoiding such failure modes requires having an accurate, in-flight measure of the implosion velocity, areal density, and remaining mass of the ablator near peak velocity. We present a new technique which achieves simultaneous time-resolved measurements of all these parameters in a single, area-backlit, x-ray streaked radiograph. This is accomplished by tomographic inversion of the radiograph to determine the radial density profile at each time step; scalar quantities such as the average position, areal density, and mass of the ablator can then be calculated by taking moments of this density profile. Details of the successful demonstration of this technique using backlit Cu-doped Be capsule implosions at the Omega facility will be presented. This work was performed under the auspices of the U.S.Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and in collaboration with Brian Spears, David Braun, Peter Celliers, Gilbert Collins, and Otto Landen at LLNL and Rick Olson at SNL.

Expected gamma-ray emission spectra from the lunar surface as a function of chemical composition

NASA Technical Reports Server (NTRS)

Reedy, R. C.; Arnold, J. R.; Trombka, J. I.

1973-01-01

The gamma rays emitted from the moon or any similar body carry information on the chemical composition of the surface layer. The elements most easily measured are K, U, Th and major elements such as O, Si, Mg, and Fe. The expected fluxes of gamma ray lines were calculated for four lunar compositions and one chondritic chemistry from a consideration of the important emission mechanisms: natural radioactivity, inelastic scatter, neutron capture, and induced radioactivity. The models used for cosmic ray interactions were those of Reedy and Arnold and Lingenfelter. The areal resolution of the experiment was calculated to be around 70 to 140 km under the conditions of the Apollo 15 and 16 experiments. Finally, a method was described for recovering the chemical information from the observed scintillation spectra obtained in these experiments.

3D MnO2-graphene composites with large areal capacitance for high-performance asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Zhai, Teng; Wang, Fuxin; Yu, Minghao; Xie, Shilei; Liang, Chaolun; Li, Cheng; Xiao, Fangming; Tang, Renheng; Wu, Qixiu; Lu, Xihong; Tong, Yexiang

2013-07-01

In this paper, we reported an effective and simple strategy to prepare large areal mass loading of MnO2 on porous graphene gel/Ni foam (denoted as MnO2/G-gel/NF) for supercapacitors (SCs). The MnO2/G-gel/NF (MnO2 mass: 13.6 mg cm-2) delivered a large areal capacitance of 3.18 F cm-2 (234.2 F g-1) and good rate capability. The prominent electrochemical properties of MnO2/G-gel/NF are attributed to the enhanced conductivities and improved accessible area for ions in electrolytes. Moreover, an asymmetric supercapacitor (ASC) based on MnO2/G-gel/NF (MnO2 mass: 6.1 mg cm-2) as the positive electrode and G-gel/NF as the negative electrode achieved a remarkable energy density of 0.72 mW h cm-3. Additionally, the fabricated ASC device also exhibited excellent cycling stability, with less than 1.5% decay after 10 000 cycles. The ability to effectively develop SC electrodes with high mass loading should open up new opportunities for SCs with high areal capacitance and high energy density.In this paper, we reported an effective and simple strategy to prepare large areal mass loading of MnO2 on porous graphene gel/Ni foam (denoted as MnO2/G-gel/NF) for supercapacitors (SCs). The MnO2/G-gel/NF (MnO2 mass: 13.6 mg cm-2) delivered a large areal capacitance of 3.18 F cm-2 (234.2 F g-1) and good rate capability. The prominent electrochemical properties of MnO2/G-gel/NF are attributed to the enhanced conductivities and improved accessible area for ions in electrolytes. Moreover, an asymmetric supercapacitor (ASC) based on MnO2/G-gel/NF (MnO2 mass: 6.1 mg cm-2) as the positive electrode and G-gel/NF as the negative electrode achieved a remarkable energy density of 0.72 mW h cm-3. Additionally, the fabricated ASC device also exhibited excellent cycling stability, with less than 1.5% decay after 10 000 cycles. The ability to effectively develop SC electrodes with high mass loading should open up new opportunities for SCs with high areal capacitance and high energy density. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01589k

Advanced LWIR hyperspectral sensor for on-the-move proximal detection of liquid/solid contaminants on surfaces

NASA Astrophysics Data System (ADS)

Giblin, Jay P.; Dixon, John; Dupuis, Julia R.; Cosofret, Bogdan R.; Marinelli, William J.

2017-05-01

Sensor technologies capable of detecting low vapor pressure liquid surface contaminants, as well as solids, in a noncontact fashion while on-the-move continues to be an important need for the U.S. Army. In this paper, we discuss the development of a long-wave infrared (LWIR, 8-10.5 μm) spatial heterodyne spectrometer coupled with an LWIR illuminator and an automated detection algorithm for detection of surface contaminants from a moving vehicle. The system is designed to detect surface contaminants by repetitively collecting LWIR reflectance spectra of the ground. Detection and identification of surface contaminants is based on spectral correlation of the measured LWIR ground reflectance spectra with high fidelity library spectra and the system's cumulative binary detection response from the sampled ground. We present the concepts of the detection algorithm through a discussion of the system signal model. In addition, we present reflectance spectra of surfaces contaminated with a liquid CWA simulant, triethyl phosphate (TEP), and a solid simulant, acetaminophen acquired while the sensor was stationary and on-the-move. Surfaces included CARC painted steel, asphalt, concrete, and sand. The data collected was analyzed to determine the probability of detecting 800 μm diameter contaminant particles at a 0.5 g/m2 areal density with the SHSCAD traversing a surface.

Estimation of Areal Distribution of Evapotranspiration Using Remotely Sensed Data During Vegetation Period in Hungary

NASA Astrophysics Data System (ADS)

Dunkel, Z.; Szenyán, I. G.

The surface temperature measured by satellite can be the basis of evapotranspiration (ET) computation. The possibility of calculation of daily sum of the regional ET using surface temperature was examined under Hungarian weather conditions. A simplified relationship, namely ETd-Rnd = a + b (Tc-Ta), which relates the daily ET to daily net radiation with one measurements of surface and air temperature was used for the calculation. Using NOAA/AVHRR satellite data, no information about the surface inhomogeneity was obtained. The distribution of surface temperature was investigated by infrared thermometer scanning the surface from a board a hang-glider, ultra-light-aeroplane, and light aeroplane. Field observation trials were made during the vegetation period of 1992, 1993, 1994 and 1995. In eastern part of the country a homogeneous field (1 km × 1 km) was scanned before noon and afternoon. In the western part of the country, a much larger area (45 km × 45 km) was investigated. Cultivated area, forest and a large water surface were included in the investigated surface. The problems of calibration of hand-held infrared thermometer and the time shifting are discussed too. Comparison of model output with data from field experiment has played a crucial role in model development and suggested evaluation method

Anomalous topography on the continental shelf around Hudson Canyon

USGS Publications Warehouse

Knebel, H.J.

1979-01-01

Recent seismic-reflection data show that the topography on the Continental Shelf around Hudson Canyon is composed of a series of depressions having variable spacings (< 100 m to 2 km), depths (1-10 m), outlines, and bottom configurations that give the sea floor an anomalous "jagged" appearance in profile. The acoustic and sedimentary characteristics, the proximity to relict shores, and the areal distribution indicate that this rough topography is an erosional surface formed on Upper Pleistocene silty sands about 13,000 to 15,000 years ago by processes related to Hudson Canyon. The pronounced southward extension of the surface, in particular, may reflect a former increase in the longshore-current erosion capacity caused by the loss of sediments over the canyon. Modern erosion or nondeposition of sediments has prevented the ubiquitous sand sheet on the Middle Atlantic shelf from covering the surface. The "anomalous" topography may, in fact, be characteristic of areas near other submarine canyons that interrupt or have interrupted the longshore drift of sediments. ?? 1979.

Buckling analysis of stiff thin films suspended on a substrate with tripod surface relief structure

NASA Astrophysics Data System (ADS)

Yu, Qingmin; Chen, Furong; Li, Ming; Cheng, Huanyu

2017-09-01

A wavy configuration is a simple yet powerful structural design strategy, which has been widely used in flexible and stretchable electronics. A buckled structure created from a prestretch-contact-release process represents an early effort. Substrates with engineered surface relief structures (e.g., rectangular islands or tripod structure) have enabled stretchability to the devices without sacrificing their electric performance (e.g., high areal coverage for LEDs/photovoltaics/batteries/supercapacitors). In particular, the substrate with a tripod surface relief structure allows wrinkled devices to be suspended on a soft tripod substrate. This minimizes the contact area between devices and the deformed substrate, which contributes to a significantly reduced interfacial stress/strain. To uncover the underlying mechanism of such a design, we exploit the energy method to analytically investigate the buckling and postbuckling behaviors of stiff films suspended on a stretchable polymeric substrate with a tripod surface relief structure. Validated by finite element analysis, the predications from such an analytical study elucidate the deformed profile and maximum strain in the buckled and postbuckled stiff thin device films, providing a useful toolkit for future experimental designs.

Pyramidal pits created by single highly charged ions in BaF{sub 2} single crystals

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

El-Said, A. S.; Physics Department, Faculty of Science, Mansoura University, 35516 Mansoura; Heller, R.

2010-07-15

In various insulators, the impact of individual slow highly charged ions (eV-keV) creates surface nanostructures, whose size depends on the deposited potential energy. Here we report on the damage created on a cleaved BaF{sub 2} (111) surface by irradiation with 4.5xq keV highly charged xenon ions from a room-temperature electron-beam ion trap. Up to charge states q=36, no surface topographic changes on the BaF{sub 2} surface are observed by scanning force microscopy. The hidden stored damage, however, can be made visible using the technique of selective chemical etching. Each individual ion impact develops into a pyramidal etch pits, as canmore » be concluded from a comparison of the areal density of observed etch pits with the applied ion fluence (typically 10{sup 8} ions/cm{sup 2}). The dimensional analysis of the measured pits reveals the significance of the deposited potential energy in the creation of lattice distortions/defects in BaF{sub 2}.« less

Infrared Surveys of Hawaiian Volcanoes: Aerial surveys with infrared imaging radiometer depict volcanic thermal patterns and structural features.

PubMed

Fisher, W A; Moxham, R M; Polcyn, F; Landis, G H

1964-11-06

Aerial infrared-sensor surveys of Kilauea volcano have depicted the areal extent and the relative intensity of abnormal thermal features in the caldera area of the volcano and along its associated rift zones. Many of these anomalies show correlation with visible steaming and reflect convective transfer of heat to the surface from subterranean sources. Structural details of the volcano, some not evident from surface observation, are also delineated by their thermal abnormalities. Several changes were observed in the patterns of infrared emission during the period of study; two such changes show correlation in location with subsequent eruptions, but the cause-and-effect relationship is uncertain. Thermal anomalies were also observed on the southwest flank of Mauna Loa; images of other volcanoes on the island of Hawaii, and of Haleakala on the island of Maui, revealed no thermal abnormalities. Approximately 25 large springs issuing into the ocean around the periphery of Hawaii have been detected. Infrared emission varies widely with surface texture and composition, suggesting that similar observations may have value for estimating surface conditions on the moon or planets.

Infrared surveys of Hawaiian volcanoes

USGS Publications Warehouse

Fischer, W. A.; Moxham, R.M.; Polcyn, F.; Landis, G.H.

1964-01-01

Aerial infrared-sensor surveys of Kilauea volcano have depicted the areal extent and the relative intensity of abnormal thermal features in the caldera area of the volcano and along its associated rift zones. Many of these anomalies show correlation with visible steaming and reflect convective transfer of heat to the surface from subterranean sources. Structural details of the volcano, some not evident from surface observation, are also delineated by their thermal abnormalities. Several changes were observed in the patterns of infrared emission during the period of study; two such changes show correlation in location with subsequent eruptions, but the cause-and-effect relationship is uncertain.Thermal anomalies were also observed on the southwest flank of Mauna Loa; images of other volcanoes on the island of Hawaii, and of Haleakala on the island of Maui, revealed no thermal abnormalities.Approximately 25 large springs issuing into the ocean around the periphery of Hawaii have been detected.Infrared emission varies widely with surface texture and composition, suggesting that similar observations may have value for estimating surface conditions on the moon or planets.

Ablation from calving and surface melt at lake-terminating Bridge Glacier, British Columbia, 1984-2013

NASA Astrophysics Data System (ADS)

Chernos, M.; Koppes, M.; Moore, R. D.

2016-01-01

Bridge Glacier is a lake-calving glacier in the Coast Mountains of British Columbia and has retreated over 3.55 km since 1972. The majority of this retreat has occurred since 1991. This retreat is substantially greater than what has been inferred from regional climate indices, suggesting that it has been driven primarily by calving as the glacier retreated across an overdeepened basin. In order to better understand the primary drivers of ablation, surface melt (below the equilibrium line altitude, ELA) and calving were quantified during the 2013 melt season using a distributed energy balance model (DEBM) and time-lapse imagery. Calving, estimated using areal change, velocity measurements, and assuming flotation were responsible for 23 % of the glacier's ablation below the ELA during the 2013 melt season and were limited by modest flow speeds and a small terminus cross-section. Calving and surface melt estimates from 1984 to 2013 suggest that calving was consistently a smaller contributor of ablation. Although calving was estimated to be responsible for up to 49 % of the glacier's ablation for individual seasons, averaged over multiple summers it accounted between 10 and 25 %. Calving was enhanced primarily by buoyancy and water depths, and fluxes were greatest between 2005 and 2010 as the glacier retreated over the deepest part of Bridge Lake. The recent rapid rate of calving is part of a transient stage in the glacier's retreat and is expected to diminish within 10 years as the terminus recedes into shallower water at the proximal end of the lake. These findings are in line with observations from other lake-calving glacier studies across the globe and suggest a common large-scale pattern in calving-induced retreat in lake-terminating alpine glaciers. Despite enhancing glacial retreat, calving remains a relatively small component of ablation and is expected to decrease in importance in the future. Hence, surface melt remains the primary driver of ablation at Bridge Glacier and thus projections of future retreat should be more closely tied to climate.

Poco Graphite Inc. SuperSiC 0.25m Mirror Cryogenic Test Result

NASA Technical Reports Server (NTRS)

Eng, Ron; Stahl, Phil; Hogue, Bill; Hadaway, James

2004-01-01

SuperSiC, a low areal density material, developed by POCO Graphite, have been used as mirror substrate for high energy lasers, laser radar systems, surveillance, telescopes, scan mirrors and satellites. SuperSiC has excellent thermal properties and cryogenic stability. It exhibits exceptional polishability for reflective optics with high strength, stiffness, and excellent thermal conductivity. A lightweighted 0.2-diameter polished SuperSic mirror was tested at cryogenic temperature at NASMSFC. Optical test results showed 6nm cry0 deformation from ambient to 30 degrees Kelvin and little to no change in its surface figure due to cry0 cycling.

A Survey of High Explosive-Induced Damage and Spall in Selected Metals Using Proton Radiography

NASA Astrophysics Data System (ADS)

Holtkamp, D. B.; Clark, D. A.; Ferm, E. N.; Gallegos, R. A.; Hammon, D.; Hemsing, W. F.; Hogan, G. E.; Holmes, V. H.; King, N. S. P.; Liljestrand, R.; Lopez, R. P.; Merrill, F. E.; Morris, C. L.; Morley, K. B.; Murray, M. M.; Pazuchanics, P. D.; Prestridge, K. P.; Quintana, J. P.; Saunders, A.; Schafer, T.; Shinas, M. A.; Stacy, H. L.

2004-07-01

Multiple spall and damage layers can be created in metal when the free surface reflects a Taylor wave generated by high explosives. These phenomena have been explored in different thicknesses of several metals (tantalum, copper, 6061 T6-aluminum, and tin) using high-energy proton radiography. Multiple images (up to 21) can be produced of the dynamic evolution of damaged material on the microsecond time scale with a <50 ns "shutter" time. Movies and multiframe still images of areal and (Abel inverted) volume densities are presented. An example of material that is likely melted on release (tin) is also presented.

Hydraulic model and flood-inundation maps developed for the Pee Dee National Wildlife Refuge, North Carolina

USGS Publications Warehouse

Smith, Douglas G.; Wagner, Chad R.

2016-04-08

A series of digital flood-inundation maps were developed on the basis of the water-surface profiles produced by the model. The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Program Web site at http://water.usgs.gov/osw/flood_inundation, depict estimates of the areal extent and depth of flooding corresponding to selected water levels at the USGS streamgage Pee Dee River at Pee Dee Refuge near Ansonville, N.C. These maps, when combined with real-time water-level information from USGS streamgages, provide managers with critical information to help plan flood-response activities and resource protection efforts.

Proposed hydrologic analyses of streamflow for Brazil

USGS Publications Warehouse

Riggs, Henry Chiles

1974-01-01

Streamflow records are evaluated for the Rio Jacui basin in the state of Rio Grande Sul, Brazil, in reference to data reliability, length of record, and density of areal coverage. Availability of water is a factor in the development of a country, and surface water is of especial importance in Brazil. This report is intended as a reference for further investigation of the flow characteristic of the basin to provide (1) information for utilization of streamflow and (2) information to improve the data collection and analytic procedures. In addition the evaluation study can serve as a pilot for other developing river basins in Brazil. (Woodard-USGS)

An all-solid-state yarn supercapacitor using cotton yarn electrodes coated with polypyrrole nanotubes.

PubMed

Wei, Chengzhuo; Xu, Qi; Chen, Zeqi; Rao, Weida; Fan, Lingling; Yuan, Ye; Bai, Zikui; Xu, Jie

2017-08-01

A novel all-solid-state yarn supercapacitor (YSC) has been fabricated by using the cotton yarns coated with polypyrrole (PPy) nanotubes. The interconnected network structure of PPy can increase the surface area as well as the electrode/electrolyte interface area, thus resulting in improved electrochemical performance. For the proposed YSC, a high areal-specific capacitance of 74.0mFcm -2 and a desirable energy density of 7.5μWhcm -2 are achieved. The flexibility of the YSC demonstrates that it is suitable for the integration as flexible power sources in wearable electronic textiles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Surface topography characterization of brass alloys: lead brass (CuZn39Pb3) and lead free brass (CuZn21Si3P)

NASA Astrophysics Data System (ADS)

Reddy, Vijeth V.; Vedantha Krishna, Amogh; Schultheiss, Fredrik; Rosén, B.-G.

2017-06-01

Manufactured surfaces usually consist of topographical features which include both those put forth by the manufacturing process, and micro-features caused by disturbances during this process. Surface characterization basically involves study of these features which influence the functionality of the surface. This article focuses on characterization of the surface topography of machined lead brass and lead free brass. The adverse effect of lead on human health and the environment has led the manufacturing sector to focus on sustainable manufacturing of lead free brass, as well as how to maintain control of the surface integrity when substituting the lead content in the brass with silicon. The investigation includes defined areal surface parameters measured on the turned samples of lead- and lead free brass using an optical coherence scanning interferometer, CSI. This paper deals with the study of surface topography of turned samples of lead- and lead free brass. It is important to study the topographical characteristics of the brass samples which are the intermediate link between the manufacturing process variables and the functional behaviour of the surface. To numerically evaluate the sample’s surface topography and to validate the measurements for a significant study, a general statistical methodology is implemented. The results indicate higher surface roughness in turned samples of lead brass compared to lead free brass.

Vegetation changes caused by fire in the Florida flatwoods as observed by remote sensing

NASA Technical Reports Server (NTRS)

Mealor, W. T., Jr.; Prunty, M. C., Jr.

1969-01-01

The nature of the flatwoods and the role that ground fires have played in maintaining them are discussed. Emphasis is placed on the areal and temporal extent of burns as recorded uniformly by remote sensors. Thermal infrared, color infrared, and Ektachrome imagery were obtained from sensors flown by a NASA aircraft at 15,000 feet over a test site in Osceola County, Florida, in March 1968. The overall pattern of burning can be sequenced and mapped uniformly from the imagery. By comparing the various imagery, areal and temporal extent of burned areas can be determined. It was concluded that remote sensed imagery provides more accurate and areally comprehensive media for assessing the impact of ground fires on the landscape of the flatwoods region than are available from any other data source.

Flash Kα radiography of laser-driven solid sphere compression for fast ignition

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

Sawada, H.; Lee, S.; Shiroto, T.

2016-06-20

Time-resolved compression of a laser-driven solid deuterated plastic sphere with a cone was measured with flash Kα x-ray radiography. A spherically converging shockwave launched by nanosecond GEKKO XII beams was used for compression while a flash of 4.51 keV Ti Kα x-ray backlighter was produced by a high-intensity, picosecond laser LFEX (Laser for Fast ignition EXperiment) near peak compression for radiography. Areal densities of the compressed core were inferred from two-dimensional backlit x-ray images recorded with a narrow-band spherical crystal imager. The maximum areal density in the experiment was estimated to be 87 ± 26 mg/cm 2. Lastly, the temporalmore » evolution of the experimental and simulated areal densities with a 2-D radiation-hydrodynamics code is in good agreement.« less

Using gamma-ray emission to measure areal density of inertial confinement fusion capsulesa)

NASA Astrophysics Data System (ADS)

Hoffman, N. M.; Wilson, D. C.; Herrmann, H. W.; Young, C. S.

2010-10-01

Fusion neutrons streaming from a burning inertial confinement fusion capsule generate gamma rays via inelastic nuclear scattering in the ablator of the capsule. The intensity of gamma-ray emission is proportional to the product of the ablator areal density (ρR) and the yield of fusion neutrons, so by detecting the gamma rays we can infer the ablator areal density, provided we also have a measurement of the capsule's total neutron yield. In plastic-shell capsules, for example, C12 nuclei emit gamma rays at 4.44 MeV after excitation by 14.1 MeV neutrons from D+T fusion. These gamma rays can be measured by a new gamma-ray detector under development. Analysis of predicted signals is in progress, with results to date indicating that the method promises to be useful for diagnosing imploded capsules.

Reducing economic risk in areally anisotropic formations with multiple-lateral horizontal wells

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

Smith, J.; Economides, M.J.; Frick, T.P.

1995-12-31

Well orientation is critical to horizontal well performance in areally anisotropic reservoirs. A horizontal well, drilled normal to the direction of maximum permeability, will have higher productivity than one drilled in any other arbitrary direction. Currently, horizontal permeability magnitudes and even indications of direction are rarely measured in the field. Based on well performance modeling and economic evaluation, this study attempts to determine the relative attractiveness of horizontal wells with multiple-laterals. The work exposes the economic risk in ignoring horizontal permeability magnitudes and directions and demonstrates the importance of adequate reservoir testing. A new rationalization for multiple-lateral horizontal wells ismore » the reduction of the economic risk associated with poor reservoir characterization in areally anisotropic formations while increasing the incremental net present value (NPV) over single-horizontal wells.« less

Individual and areal risk factors for road traffic injury deaths: nationwide study in South Korea.

PubMed

Park, Kunhee; Hwang, Seung-Sik; Lee, Jin-Seok; Kim, Yoon; Kwon, Soonman

2010-07-01

This study determines the individual and areal risk factors for road traffic injury deaths in South Korea. The risk factors that influence road traffic injury deaths are defined by multilevel Poisson regression analysis. It is seen that not only demographic factors but also individual educational level, which represents socioeconomic status, influences road traffic injury deaths. The material deprivation index, which represents areal socioeconomic status, and W statistics, as a measure of the quality of the emergency medical system in an area, also influence road traffic injury deaths. Based on this study, the most vulnerable group for road traffic injury deaths is elderly men with a low level of education who live in the most deprived areas.Therefore, preventive policies focusing on both these areas and this population demographic should be established.

Flash Kα radiography of laser-driven solid sphere compression for fast ignition

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

Sawada, H.; Lee, S.; Nagatomo, H.

2016-06-20

Time-resolved compression of a laser-driven solid deuterated plastic sphere with a cone was measured with flash Kα x-ray radiography. A spherically converging shockwave launched by nanosecond GEKKO XII beams was used for compression while a flash of 4.51 keV Ti Kα x-ray backlighter was produced by a high-intensity, picosecond laser LFEX (Laser for Fast ignition EXperiment) near peak compression for radiography. Areal densities of the compressed core were inferred from two-dimensional backlit x-ray images recorded with a narrow-band spherical crystal imager. The maximum areal density in the experiment was estimated to be 87 ± 26 mg/cm{sup 2}. The temporal evolution of the experimental andmore » simulated areal densities with a 2-D radiation-hydrodynamics code is in good agreement.« less

Heat-assisted magnetic recording of bit-patterned media beyond 10 Tb/in2

NASA Astrophysics Data System (ADS)

Vogler, Christoph; Abert, Claas; Bruckner, Florian; Suess, Dieter; Praetorius, Dirk

2016-03-01

The limits of areal storage density that is achievable with heat-assisted magnetic recording are unknown. We addressed this central question and investigated the areal density of bit-patterned media. We analyzed the detailed switching behavior of a recording bit under various external conditions, allowing us to compute the bit error rate of a write process (shingled and conventional) for various grain spacings, write head positions, and write temperatures. Hence, we were able to optimize the areal density yielding values beyond 10 Tb/in2. Our model is based on the Landau-Lifshitz-Bloch equation and uses hard magnetic recording grains with a 5-nm diameter and 10-nm height. It assumes a realistic distribution of the Curie temperature of the underlying material, grain size, as well as grain and head position.

Facile preparation of polypyrrole/graphene oxide nanocomposites with large areal capacitance using electrochemical codeposition for supercapacitors

NASA Astrophysics Data System (ADS)

Zhou, Haihan; Han, Gaoyi; Xiao, Yaoming; Chang, Yunzhen; Zhai, Hua-Jin

2014-10-01

A simple and low-cost electrochemical codeposition method has been introduced to fabricate polypyrrole/graphene oxide (PPy/GO) nanocomposites and the areal capacitance of conducting polymer/GO composites is reported for the first time. Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) are implemented to determine the PPy/GO nanocomposites are successfully prepared and the interaction between PPy and GO. The as-prepared PPy/GO nanocomposites show the curly sheet-like morphology, superior capacitive behaviors and cyclic stability. Furthermore, the varying deposition time is implemented to investigate the impact of the loading amount on electrochemical behavior of the composites, and a high areal capacitance of 152 mF cm-2 is achieved at 10 mV s-1 CV scan. However, the thicker films caused by the long deposition time would result in larger diffusion resistance of electrolyte ions, consequently exhibit the relatively lower capacitance value at the high current density. The GCD tests indicate moderate deposition time is more suitable for the fast charge/discharge. Considering the very simple and effective synthetic process, the PPy/GO nanocomposites with relatively high areal capacitance are competitive candidate for supercapacitor application, and its capacitive performances can be easily tuned by varying the deposition time.

A multivariate spatial mixture model for areal data: examining regional differences in standardized test scores

PubMed Central

Neelon, Brian; Gelfand, Alan E.; Miranda, Marie Lynn

2013-01-01

Summary Researchers in the health and social sciences often wish to examine joint spatial patterns for two or more related outcomes. Examples include infant birth weight and gestational length, psychosocial and behavioral indices, and educational test scores from different cognitive domains. We propose a multivariate spatial mixture model for the joint analysis of continuous individual-level outcomes that are referenced to areal units. The responses are modeled as a finite mixture of multivariate normals, which accommodates a wide range of marginal response distributions and allows investigators to examine covariate effects within subpopulations of interest. The model has a hierarchical structure built at the individual level (i.e., individuals are nested within areal units), and thus incorporates both individual- and areal-level predictors as well as spatial random effects for each mixture component. Conditional autoregressive (CAR) priors on the random effects provide spatial smoothing and allow the shape of the multivariate distribution to vary flexibly across geographic regions. We adopt a Bayesian modeling approach and develop an efficient Markov chain Monte Carlo model fitting algorithm that relies primarily on closed-form full conditionals. We use the model to explore geographic patterns in end-of-grade math and reading test scores among school-age children in North Carolina. PMID:26401059

Observation of strong oscillations of areal mass in an unsupported shock wave produced by a short laser pulse

NASA Astrophysics Data System (ADS)

Aglitskiy, Y.; Karasik, M.; Velikovich, A. L.; Serlin, V.; Weaver, J. L.; Kessler, T. J.; Schmitt, A. J.; Obenschain, S. P.; Metzler, N.; Oh, J.

2011-10-01

The first experimental study of hydrodynamic perturbation evolution in a strong unsupported shock wave, which is immediately followed by a rarefaction wave, is reported. Our planar solid polystyrene laser-machined targets, 50 to 100 μm thick, rippled from the front side with a single-mode wavelength 30 or 45 μm and peak-to-valley amplitude 4 to 6 μm, were irradiated with a 350 ps long Nike KrF laser pulse at peak intensity of up to 330 TW/cm2. The perturbation evolution in the target was observed using face-on monochromatic x-ray radiography while the pulse lasted and for 3 to 4 ns after it ended. While the driving pulse was on, the areal mass modulation amplitude in the target was observed to grow by a factor of up to ~4 due to the ablative Richtmyer-Meshkov instability. After the end of the pulse, while the strong unsupported shock wave propagated through the unperturbed target, the theoretically predicted large oscillations of the areal mass [A. L. Velikovich et al., Phys. Plasmas 10, 3270 (2003)] were observed. Multiple phase reversals of the areal mass modulation have been detected. Work supported by DOE/NNSA and Office of Naval Research.

A data-management system for detailed areal interpretive data

USGS Publications Warehouse

Ferrigno, C.F.

1986-01-01

A data storage and retrieval system has been developed to organize and preserve areal interpretive data. This system can be used by any study where there is a need to store areal interpretive data that generally is presented in map form. This system provides the capability to grid areal interpretive data for input to groundwater flow models at any spacing and orientation. The data storage and retrieval system is designed to be used for studies that cover small areas such as counties. The system is built around a hierarchically structured data base consisting of related latitude-longitude blocks. The information in the data base can be stored at different levels of detail, with the finest detail being a block of 6 sec of latitude by 6 sec of longitude (approximately 0.01 sq mi). This system was implemented on a mainframe computer using a hierarchical data base management system. The computer programs are written in Fortran IV and PL/1. The design and capabilities of the data storage and retrieval system, and the computer programs that are used to implement the system are described. Supplemental sections contain the data dictionary, user documentation of the data-system software, changes that would need to be made to use this system for other studies, and information on the computer software tape. (Lantz-PTT)

An application of sample entropy to precipitation in Paraíba State, Brazil

NASA Astrophysics Data System (ADS)

Xavier, Sílvio Fernando Alves; da Silva Jale, Jader; Stosic, Tatijana; dos Santos, Carlos Antonio Costa; Singh, Vijay P.

2018-05-01

A climate system is characterized to be a complex non-linear system. In order to describe the complex characteristics of precipitation series in Paraíba State, Brazil, we aim the use of sample entropy, a kind of entropy-based algorithm, to evaluate the complexity of precipitation series. Sixty-nine meteorological stations are distributed over four macroregions: Zona da Mata, Agreste, Borborema, and Sertão. The results of the analysis show that intricacies of monthly average precipitation have differences in the macroregions. Sample entropy is able to reflect the dynamic change of precipitation series providing a new way to investigate complexity of hydrological series. The complexity exhibits areal variation of local water resource systems which can influence the basis for utilizing and developing resources in dry areas.

Hydrogeology and water quality of at the management systems evaluation area near Piketon, Ohio

USGS Publications Warehouse

Jagucki, M.L.; Finton, C.D.; Springer, A.E.; Bair, E.S.

1995-01-01

This report presents the results of a study by the U.S. Geological Survey, The Ohio State University, and the U.S. Department of Agriculture to describe the hydrology, water quality, and geochemical factors controlling water quality at the Ohio Management Systems Evaluation Area (MSEA). The Ohio MSEA is located on a 650-acre farm in the Scioto River Valley in Pike County, south-central Ohio. The farm is underlain by an incised bedrock valley filled with about 70 feet of sand and gravel outwash deposits that are covered by a veneer of silty clay alluvium and silty loam and sandy loam soils. Outwash sediment are composed predominantly of dolomite, quartz, and calcite, and have a median organic carbon concentration of 0.39 weight percent. Horizontal hydraulic conductivity of the sediment based on results of multiple-well aquifer tests ranges from 400 to 560 feet per day. Ground-water flow is from east to west-southwest at an average velocity of 1.5 to 2.5 feet per day. Ground water and surface water at the site are highly interconnected. Big Beaver Creek recharges the outwash aquifer along the eastern edge of the study area, and ground water discharges to the Scioto River at the western edge of the study area. High-stage events on the Scioto River cause frequent flow reversals in the aquifer that allow streamwater to travel a maximum observed distance of 190 feet inland. A zone of oxidizing waters (characterized by high dissolved oxygen concentration and Eh) is found in shallow ground water for several hundred feet adjacent to Big Beaver Creek and the Scioto River. This zone of oxidizing ground water is caused by the periodic inflow of surface waters to the aquifer. A ground-water budget for the study area indicates that the aquifer received 17.7 inches of recharge during water year 1992; of this amount, 72 percent originated as infiltrating precipitation, 28 percent as infiltration of surface water from Big Beaver Creek, and 0.2 percent as leakage from bedrock. Areal variation in water quality is caused by areal differences in the relative importance of these three recharge sources. The effects of bedrock leakage are evident only in the northeast corner of the study area. Here, deep outwash waters are transitional in composition between the calcium magnesium bicarbonate waters found elsewhere in the outwash aquifer and the calcium sodium chloride waters of the bedrock aquifer. Mixing calculations indicate that these deep outwash waters are composed of as much as 26 percent bedrock water. In the southern part of the MSEA, ground water is diluted by surface water from Big Beaver Creek as it recharges the aquifer through a sand and gravel streambed. At the northeast corner of the MSEA, however, Big Beaver Creek flows across a shale streambed through which no infiltration occurs. Redox reactions in the outwash aquifer control variations in aquifer chemistry with depth. From the water table to about 40 feet below land surface, oxidizing conditions are characterized by the presence of dissolved oxygen and nitrates in ground water, Eh greater than 200 millivolts, ferrihydrite coatings on sediment grains, and the absence of dissolved iron and manganese. From about 40 feet below land surface to the base of the aquifer, reducing conditions are characterized by dissolved oxygen concentrations less than 2 mg/L, Eh less than 200 millivolts, and the presence of dissolved iron and manganese. Denitrification in the reducing zone naturally remediates anthropogenic nitrate contamination of the aquifer while oxidizing pyrite in the aquifer sediment. ? The Ohio State University, Department of Geological Sciences, Columbus, Ohio.

Evaluating earthquake hazards in the Los Angeles region; an earth-science perspective

USGS Publications Warehouse

Ziony, Joseph I.

1985-01-01

Potentially destructive earthquakes are inevitable in the Los Angeles region of California, but hazards prediction can provide a basis for reducing damage and loss. This volume identifies the principal geologically controlled earthquake hazards of the region (surface faulting, strong shaking, ground failure, and tsunamis), summarizes methods for characterizing their extent and severity, and suggests opportunities for their reduction. Two systems of active faults generate earthquakes in the Los Angeles region: northwest-trending, chiefly horizontal-slip faults, such as the San Andreas, and west-trending, chiefly vertical-slip faults, such as those of the Transverse Ranges. Faults in these two systems have produced more than 40 damaging earthquakes since 1800. Ninety-five faults have slipped in late Quaternary time (approximately the past 750,000 yr) and are judged capable of generating future moderate to large earthquakes and displacing the ground surface. Average rates of late Quaternary slip or separation along these faults provide an index of their relative activity. The San Andreas and San Jacinto faults have slip rates measured in tens of millimeters per year, but most other faults have rates of about 1 mm/yr or less. Intermediate rates of as much as 6 mm/yr characterize a belt of Transverse Ranges faults that extends from near Santa Barbara to near San Bernardino. The dimensions of late Quaternary faults provide a basis for estimating the maximum sizes of likely future earthquakes in the Los Angeles region: moment magnitude .(M) 8 for the San Andreas, M 7 for the other northwest-trending elements of that fault system, and M 7.5 for the Transverse Ranges faults. Geologic and seismologic evidence along these faults, however, suggests that, for planning and designing noncritical facilities, appropriate sizes would be M 8 for the San Andreas, M 7 for the San Jacinto, M 6.5 for other northwest-trending faults, and M 6.5 to 7 for the Transverse Ranges faults. The geologic and seismologic record indicates that parts of the San Andreas and San Jacinto faults have generated major earthquakes having recurrence intervals of several tens to a few hundred years. In contrast, the geologic evidence at points along other active faults suggests recurrence intervals measured in many hundreds to several thousands of years. The distribution and character of late Quaternary surface faulting permit estimation of the likely location, style, and amount of future surface displacements. An extensive body of geologic and geotechnical information is used to evaluate areal differences in future levels of shaking. Bedrock and alluvial deposits are differentiated according to the physical properties that control shaking response; maps of these properties are prepared by analyzing existing geologic and soils maps, the geomorphology of surficial units, and. geotechnical data obtained from boreholes. The shear-wave velocities of near-surface geologic units must be estimated for some methods of evaluating shaking potential. Regional-scale maps of highly generalized shearwave velocity groups, based on the age and texture of exposed geologic units and on a simple two-dimensional model of Quaternary sediment distribution, provide a first approximation of the areal variability in shaking response. More accurate depictions of near-surface shear-wave velocity useful for predicting ground-motion parameters take into account the thickness of the Quaternary deposits, vertical variations in sediment .type, and the correlation of shear-wave velocity with standard penetration resistance of different sediments. A map of the upper Santa Ana River basin showing shear-wave velocities to depths equal to one-quarter wavelength of a 1-s shear wave demonstrates the three-dimensional mapping procedure. Four methods for predicting the distribution and strength of shaking from future earthquakes are presented. These techniques use different measures of strong-motion

Creating surfactant nanoparticles for block copolymer composites through surface chemistry.

PubMed

Kim, Bumjoon J; Bang, Joona; Hawker, Craig J; Chiu, Julia J; Pine, David J; Jang, Se Gyu; Yang, Seung-Man; Kramer, Edward J

2007-12-04

A simple strategy to tailor the surface of nanoparticles for their specific adsorption to and localization at block copolymer interfaces was explored. Gold nanoparticles coated by a mixture of low molecular weight thiol end-functional polystyrene (PS-SH) (Mn = 1.5 and 3.4 kg/mol) and poly(2-vinylpyridine) homopolymers (P2VP-SH) (Mn = 1.5 and 3.0 kg/mol) were incorporated into a lamellar poly(styrene-b-2-vinylpyridine) diblock copolymer (PS-b-P2VP) (Mn = 196 kg/mol). A library of nanoparticles with varying PS and P2VP surface compositions (FPS) and high polymer ligand areal chain densities was synthesized. The location of the nanoparticles in the PS-b-P2VP block copolymer was determined by transmission electron microscopy. Sharp transitions in particle location from the PS domain to the PS/P2VP interface, and subsequently to the P2VP domain, were observed at FPS = 0.9 and 0.1, respectively. This extremely wide window of FPS values where the polymer-coated gold nanoparticles adsorb to the interface suggests a redistribution of PS and P2VP polymers on the Au surface, inducing the formation of amphiphilic nanoparticles at the PS/P2VP interface. In a second and synthetically more challenging approach, gold nanoparticles were covered with a thiol terminated random copolymer of styrene and 2-vinylpyridine synthesized by RAFT polymerization. Two different random copolymers were considered, where the molecular weight was fixed at 3.5 kg/mol and the relative incorporation of styrene and 2-vinylpyridine repeat units varied (FPS = 0.52 and 0.40). The areal chain density of these random copolymers on Au is unfortunately not high enough to preclude any contact between the P2VP block of the block copolymer and the Au surface. Interestingly, gold nanoparticles coated by the random copolymer with FPS = 0.4 were dispersed in the P2VP domain, while those with FPS = 0.52 were located at the interface. A simple calculation for the adsorption energy to the interface of the nanoparticles with different surface arrangements of PS and P2VP ligands supports evidence for the rearrangement of thiol terminated homopolymers. An upper limit estimate of the adsorption energy of nanoparticles uniformly coated with a random arrangement of PS and P2VP ligands where a 10% surface area was occupied by P2VP -mers or chains was approximately 1 kBT, which indicates that such nanoparticles are unlikely to be segregated along the interface, in contrast to the experimental results for nanoparticles with mixed ligand-coated surfaces.

A Fluorinated Ether Electrolyte Enabled High Performance Prelithiated Graphite/Sulfur Batteries

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

Chen, Shuru; Yu, Zhaoxin; Gordin, Mikhail L.

Lithium/sulfur (Li/S) batteries have attracted great attention as a promising energy storage technology, but so far their practical applications are greatly hindered by issues of polysulfide shuttling and unstable lithium/electrolyte interface. To address these issues, a feasible strategy is to construct a rechargeable prelithiated graphite/sulfur batteries. In this study, a fluorinated ether of bis(2,2,2-trifluoroethyl) ether (BTFE) was reported to blend with 1,3-dioxolane (DOL) for making a multifunctional electrolyte of 1.0 M LiTFSI DOL/BTFE (1:1, v/v) to enable high performance prelithiated graphite/S batteries. First, the electrolyte significantly reduces polysulfide solubility to suppress the deleterious polysulfide shuttling and thus improves capacity retentionmore » of sulfur cathodes. Second, thanks to the low viscosity and good wettability, the fluorinated electrolyte dramatically enhances the reaction kinetics and sulfur utilization of high-areal-loading sulfur cathodes. More importantly, this electrolyte forms a stable solid-electrolyte interphase (SEI) layer on graphite surface and thus enables remarkable cyclability of graphite anodes. Lastly, by coupling prelithiated graphite anodes with sulfur cathodes with high areal capacity of ~3 mAh cm -2, we demonstrate prelithiated graphite/sulfur batteries that show high sulfur-specific capacity of ~1000 mAh g -1 and an excellent capacity retention of >65% after 450 cycles at C/10.« less

High-performance lithium-ion batteries with 1.5 μm thin copper nanowire foil as a current collector

NASA Astrophysics Data System (ADS)

Chu, Hsun-Chen; Tuan, Hsing-Yu

2017-04-01

Cu Foil, a thin sheet of Cu, is the common anode current collector in commercial lithium ion batteries (LIBs) which accounts for ∼ 10 wt% of the total cell weight. However, thickness reduction of LIB-based Cu foils below 6 μm has been limited by the incapability of conventional rolling annealing or electrodeposition process. We here report a new type of Cu foil, so called Cu nanowire foil (CuNW foil), for use as an LIB anode current collector. We fabricate Cu NW foils by rolling press Cu nanowire fabric to reduce the thickness down to ∼1.5 μm with an areal weight down to ∼1.2 mg cm-2 and a density approximately 96% to that of bulk Cu. The rough surface and porous structure of CuNW foil enable better wetting and adhering properties of graphite slurry on foil. In full cell examination, a cell of a areal capacity of 3 mAh cm-2 exhibits 83.6% capacity retention for 600 cycles at 0.6 C that meets the standard specification of most commercial LIBs. As a proof-of-concept of demonstration, we fabricate a 700 mA pouch-type battery implemented with graphite-Cu NWs foil anodes to serve as energy supply to operate electronic devices.

Neuronal correlates of the five factor model (FFM) of human personality: Multimodal imaging in a large healthy sample.

PubMed

Bjørnebekk, Astrid; Fjell, Anders M; Walhovd, Kristine B; Grydeland, Håkon; Torgersen, Svenn; Westlye, Lars T

2013-01-15

Advances in neuroimaging techniques have recently provided glimpse into the neurobiology of complex traits of human personality. Whereas some intriguing findings have connected aspects of personality to variations in brain morphology, the relations are complex and our current understanding is incomplete. Therefore, we aimed to provide a comprehensive investigation of brain-personality relations using a multimodal neuroimaging approach in a large sample comprising 265 healthy individuals. The NEO Personality Inventory was used to provide measures of core aspects of human personality, and imaging phenotypes included measures of total and regional brain volumes, regional cortical thickness and arealization, and diffusion tensor imaging indices of white matter (WM) microstructure. Neuroticism was the trait most clearly linked to brain structure. Higher neuroticism including facets reflecting anxiety, depression and vulnerability to stress was associated with smaller total brain volume, widespread decrease in WM microstructure, and smaller frontotemporal surface area. Higher scores on extraversion were associated with thinner inferior frontal gyrus, and conscientiousness was negatively associated with arealization of the temporoparietal junction. No reliable associations between brain structure and agreeableness and openness, respectively, were found. The results provide novel evidence of the associations between brain structure and variations in human personality, and corroborate previous findings of a consistent neuroanatomical basis of negative emotionality. Copyright © 2012 Elsevier Inc. All rights reserved.

A Fluorinated Ether Electrolyte Enabled High Performance Prelithiated Graphite/Sulfur Batteries

DOE PAGES

Chen, Shuru; Yu, Zhaoxin; Gordin, Mikhail L.; ...

2017-02-03

Lithium/sulfur (Li/S) batteries have attracted great attention as a promising energy storage technology, but so far their practical applications are greatly hindered by issues of polysulfide shuttling and unstable lithium/electrolyte interface. To address these issues, a feasible strategy is to construct a rechargeable prelithiated graphite/sulfur batteries. In this study, a fluorinated ether of bis(2,2,2-trifluoroethyl) ether (BTFE) was reported to blend with 1,3-dioxolane (DOL) for making a multifunctional electrolyte of 1.0 M LiTFSI DOL/BTFE (1:1, v/v) to enable high performance prelithiated graphite/S batteries. First, the electrolyte significantly reduces polysulfide solubility to suppress the deleterious polysulfide shuttling and thus improves capacity retentionmore » of sulfur cathodes. Second, thanks to the low viscosity and good wettability, the fluorinated electrolyte dramatically enhances the reaction kinetics and sulfur utilization of high-areal-loading sulfur cathodes. More importantly, this electrolyte forms a stable solid-electrolyte interphase (SEI) layer on graphite surface and thus enables remarkable cyclability of graphite anodes. Lastly, by coupling prelithiated graphite anodes with sulfur cathodes with high areal capacity of ~3 mAh cm -2, we demonstrate prelithiated graphite/sulfur batteries that show high sulfur-specific capacity of ~1000 mAh g -1 and an excellent capacity retention of >65% after 450 cycles at C/10.« less

Chemical Analyses of Ground Water in the Carson Desert near Stillwater, Churchill County, Nevada, 2005

USGS Publications Warehouse

Fosbury, DeEtta; Walker, Mark; Stillings, Lisa L.

2008-01-01

This report presents the chemical analyses of ground-water samples collected in 2005 from domestic wells located in the Stillwater area of the Carson Desert (fig. 1). These data were evaluated for evidence of mixing with nearby geothermal waters (Fosbury, 2007). That study used several methods to identify mixing zones of ground and geothermal waters using trace elements, chemical equilibria, water temperature, geothermometer estimates, and statistical techniques. In some regions, geothermal sources influence the chemical quality of ground water used for drinking water supplies. Typical geothermal contaminants include arsenic, mercury, antimony, selenium, thallium, boron, lithium, and fluoride (Webster and Nordstrom, 2003). The Environmental Protection Agency has established primary drinking water standards for these, with the exception of boron and lithium. Concentrations of some trace metals in geothermal water may exceed drinking water standards by several orders of magnitude. Geothermal influences on water quality are likely to be localized, depending on directions of ground water flow, the relative volumes of geothermal sources and ground water originating from other sources, and depth below the surface from which water is withdrawn. It is important to understand the areal extent of shallow mixing of geothermal water because it may have adverse chemical and aesthetic effects on domestic drinking water. It would be useful to understand the areal extent of these effects.

Dome growth at Mount Cleveland, Aleutian Arc, quantified by time-series TerraSAR-X imagery

USGS Publications Warehouse

Wang, Teng; Poland, Michael; Lu, Zhong

2016-01-01

Synthetic aperture radar imagery is widely used to study surface deformation induced by volcanic activity; however, it is rarely applied to quantify the evolution of lava domes, which is important for understanding hazards and magmatic system characteristics. We studied dome formation associated with eruptive activity at Mount Cleveland, Aleutian Volcanic Arc, in 2011–2012 using TerraSAR-X imagery. Interferometry and offset tracking show no consistent deformation and only motion of the crater rim, suggesting that ascending magma may pass through a preexisting conduit system without causing appreciable surface deformation. Amplitude imagery has proven useful for quantifying rates of vertical and areal growth of the lava dome within the crater from formation to removal by explosive activity to rebirth. We expect that this approach can be applied at other volcanoes that host growing lava domes and where hazards are highly dependent on dome geometry and growth rates.

Geoelectrical mapping and groundwater contamination

NASA Astrophysics Data System (ADS)

Blum, Rainer

Specific electrical resistivity of near-surface materials is mainly controlled by the groundwater content and thus reacts extremely sensitive to any change in the ion content. Geoelectric mapping is a well-established, simple, and inexpensive technique for observing areal distributions of apparent specific electrical resistivities. These are a composite result of the true resistivities in the underground, and with some additional information the mapping of apparent resistivities can help to delineate low-resistivity groundwater contaminations, typically observed downstream from sanitary landfills and other waste sites. The presence of other good conductors close to the surface, mainly clays, is a serious noise source and has to be sorted out by supporting observations of conductivities in wells and geoelectric depth soundings. The method may be used to monitor the extent of groundwater contamination at a specific time as well as the change of a contamination plume with time, by carrying out repeated measurements. Examples for both are presented.

Geophysical, geochemical, and geological investigations of the Dunes geothermal system, Imperial Valley, California

NASA Technical Reports Server (NTRS)

Elders, W. A.; Combs, J.; Coplen, T. B.; Kolesar, P.; Bird, D. K.

1974-01-01

The Dunes anomaly is a water-dominated geothermal system in the alluvium of the Salton Trough, lacking any surface expression. It was discovered by shallow-temperature gradient measurements. A 612-meter-deep test well encountered several temperature-gradient reversals, with a maximum of 105 C at 114 meters. The program involves surface geophysics, including electrical, gravity, and seismic methods, down-hole geophysics and petrophysics of core samples, isotopic and chemical studies of water samples, and petrological and geochemical studies of the cores and cuttings. The aim is (1) to determine the source and temperature history of the brines, (2) to understand the interaction between the brines and rocks, and (3) to determine the areal extent, nature, origin, and history of the geothermal system. These studies are designed to provide better definition of exploration targets for hidden geothermal anomalies and to contribute to improved techniques of exploration and resource assessment.

A kilobyte rewritable atomic memory

NASA Astrophysics Data System (ADS)

Kalff, Floris; Rebergen, Marnix; Fahrenfort, Nora; Girovsky, Jan; Toskovic, Ranko; Lado, Jose; FernáNdez-Rossier, JoaquíN.; Otte, Sander

The ability to manipulate individual atoms by means of scanning tunneling microscopy (STM) opens op opportunities for storage of digital data on the atomic scale. Recent achievements in this direction include data storage based on bits encoded in the charge state, the magnetic state, or the local presence of single atoms or atomic assemblies. However, a key challenge at this stage is the extension of such technologies into large-scale rewritable bit arrays. We demonstrate a digital atomic-scale memory of up to 1 kilobyte (8000 bits) using an array of individual surface vacancies in a chlorine terminated Cu(100) surface. The chlorine vacancies are found to be stable at temperatures up to 77 K. The memory, crafted using scanning tunneling microscopy at low temperature, can be read and re-written automatically by means of atomic-scale markers, and offers an areal density of 502 Terabits per square inch, outperforming state-of-the-art hard disk drives by three orders of magnitude.

Using Levee Setbacks to Increase Floodplain Connectivity and Reduce Flood Risk

NASA Astrophysics Data System (ADS)

Dahl, T. A.; Echevarria-Doyle, W.

2017-12-01

Levees typically constrain flood flows to within the main channel, isolating the river from its natural floodplain. Levees limit the areal and temporal extents of flooding, but can increase flood peaks, alter ecosystems, and cause scour. In order to mitigate these effects, some groups have begun moving portions of levees further away from the main channel, creating setback levees. Here we describe a series of levee setback scenarios for a hypothetical river that were modeled with the unsteady, 2D-hydraulic model AdH. In our scenarios, the water surface elevations were reduced both at the location of the levee setback and for some distance upstream. The models also show that the floodplain roughness can have a greater effect on the reduction in water surface elevation than the size of the levee setback. Groups planning levee setbacks can use these results to help guide their designs.

Large deployable antenna program. Phase 1: Technology assessment and mission architecture

NASA Technical Reports Server (NTRS)

Rogers, Craig A.; Stutzman, Warren L.

1991-01-01

The program was initiated to investigate the availability of critical large deployable antenna technologies which would enable microwave remote sensing missions from geostationary orbits as required for Mission to Planet Earth. Program goals for the large antenna were: 40-meter diameter, offset-fed paraboloid, and surface precision of 0.1 mm rms. Phase 1 goals were: to review the state-of-the-art for large, precise, wide-scanning radiometers up to 60 GHz; to assess critical technologies necessary for selected concepts; to develop mission architecture for these concepts; and to evaluate generic technologies to support the large deployable reflectors necessary for these missions. Selected results of the study show that deployable reflectors using furlable segments are limited by surface precision goals to 12 meters in diameter, current launch vehicles can place in geostationary only a 20-meter class antenna, and conceptual designs using stiff reflectors are possible with areal densities of 2.4 deg/sq m.

The spatial distribution of rocks on Mars

NASA Astrophysics Data System (ADS)

Christensen, P. R.

1986-11-01

A Viking IR Thematic Mapper observations-based mapping of the spatial distribution of rocks exposed on the planet's surface exhibits a 6-percent areal coverage rock abundance. A model for the determination of rock abundance relates the thermal emission in each of the four Thematic Mapper bands to temperature contrasts in the field of view as well as to nonunit thermal emissivity due to absorption bands in the surface materials and the scattering of the outgoing energy by atmospheric dust and water ice; since each of these produces characteristic spectral and diurnal signatures, they can be readily separated. Dual-polarization radar measurements show the Tharsis volcanic region to be very rough, while thermal measurements indicate few rocks, accompanied by a dust covering. These observations suggest an approximately 1-km thick mantle of fines, overlying a rough subsurface, on which both erosional and depositional aeolian processes have exerted considerable influence.

Quaternary geologic map of the Lake Erie 4 degrees x 6 degrees quadrangle, United States and Canada

USGS Publications Warehouse

Fullerton, David S.; Richmond, Gerald M.; state compilations by Fullerton, David S.; Cowan, W.R.; Sevon, W.D.; Goldthwait, R.P.; Farrand, W.R.; Muller, E.H.; Behling, R.E.; Stravers, J.A.; edited and integrated by Fullerton, David S.; Richmond, Gerald Martin

1991-01-01

The Quaternary Geologic Map of the Lake Erie 4? x 6? Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

Quaternary geologic map of the Quebec 4 degrees x 6 degrees quadrangle, United States and Canada

USGS Publications Warehouse

State compilations by Borns, H. W.; Gadd, N.R.; LaSalle, Pierre; Martineau, Ghismond; Chauvin, Luc; Fulton, R.J.; Chapman, W.F.; Wagner, W.P.; Grant, D.R.; edited and integrated by Richmond, Gerald Martin; Fullerton, David S.

1987-01-01

The Quaternary Geologic Map of the Quebec 4? x 6? Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the Earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

Quaternary geologic map of the Chicago 4 degrees x 6 degrees quadrangle, United States

USGS Publications Warehouse

State compilations by Lineback, Jerry A.; Bleuer, Ned K.; Mickelson, David M.; Farrand, William R.; Goldthwait, Richard P.; Edited and integrated by Richmond, Gerald M.; Fullerton, David S.

1983-01-01

The Quaternary Geologic Map of the Chicago 4 degree x 6 degree Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

Quaternary geologic map of the Sudbury 4 degree by 6 degree quadrangle, United States and Canada

USGS Publications Warehouse

Fullerton, David S.; Sado, Edward V.; Baker, C.L.; Farrand, William R.

2004-01-01

The Quaternary Geologic Map of the Sudbury 4 degrees x 6 degrees Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

Quaternary geologic map of the Ottawa 4 degrees x 6 degrees quadrangle, United States and Canada

USGS Publications Warehouse

Fullerton, David S.; Gadd, N. R.; Veillette, J.J.; Wagner, P.W.; Chapman, W.F.

1993-01-01

The Quaternary Geologic Map of the Ottawa 4 degree x 6 degree Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

Quaternary geologic map of the Dallas 4° x 6° quadrangle, United States

USGS Publications Warehouse

State compilations by Luza, Kenneth V.; Jensen, Kathryn M.; Fishman, W.D.; Wermund, E.G.; Richmond, Gerald Martin; edited and integrated by Richmond, Gerald Martin; Christiansen, Ann Coe; Bush, Charles A.

1994-01-01

The Quaternary Geologic Map of the Dallas 4° x 6° Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the Earth. They make up the ground on which we walk, the dirt in which we dig foundations, and the soil in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

Quaternary geologic map of the Chesapeake Bay 4 degrees x 6 degrees quadrangle, United States

USGS Publications Warehouse

State compilations by Cleaves, Emery T.; Glaser, John D.; Howard, Alan D.; Johnson, Gerald H.; Wheeler, Walter H.; Sevon, William D.; Judson, Sheldon; Owens, James P.; Peebles, Pamela C.; edited and integrated by Richmond, Gerald Martin; Fullerton, David S.; Weide, David L.

1987-01-01

The Quaternary Geologic Map of the Chesapeake Bay 4? x 6? Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the Earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

Quaternary geologic map of the Lake Superior 4 degrees x 6 degrees quadrangle, United States and Canada

USGS Publications Warehouse

Richmond, Gerald M.; Fullerton, David S.; state compilations by Farrand, William R.; Mickelson, D.M.; Cowan, W.R.; Goebel, J.E.; edited and integrated by Richmond, Gerald Martin

1984-01-01

The Quaternary Geologic Map of the Lake Superior 4? x 6? Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

Quaternary geologic map of the Hudson River 4 degree x 6 degree quadrangle, United States and Canada

USGS Publications Warehouse

State and province compilations by Fullerton, David S.; Sevon, William D.; Muller, Ernest H.; Judson, Sheldon; Black, Robert F.; Wagner, Phillip W.; Hartshorn, Joseph H.; Chapman, William F.; Cowan, William D.; edited and integrated by Fullerton, David S.

1992-01-01

The Quaternary Geologic Map of the Hudson River 4? x 6? Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

Quaternary geologic map of the Ozark Plateau 4 ° x 6 ° quadrangle, United States

USGS Publications Warehouse

State compilations by Whitfield, John William; Ward, R.A.; Denne, J.E.; Holbrook, D.F.; Bush, W.V.; Lineback, J.A.; Luza, K.V.; Jensen, Kathleen M.; Fishman, W.D.; Richmond, Gerald Martin; Weide, David L.; Bush, Charles A.

1993-01-01

The Quaternary Geologic Map of the Ozark Plateau 4° x 6° Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the "ground" on which we walk, the "dirt" in which we dig foundations, and the "soil" in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

Quaternary geologic map of the Boston 4 degrees x 6 degrees quadrangle, United States and Canada

USGS Publications Warehouse

State compilations by Hartshorn, Joseph H.; Thompson, W.B.; Chapman, W.F.; Black, R.F.; Richmond, Gerald Martin; Grant, D.R.; Fullerton, David S.; edited and integrated by Richmond, Gerald Martin

1991-01-01

The Quaternary Geologic Map of the Boston 4 deg x 6 deg Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

Evaluation of the capabilities of satellite imagery for monitoring regional air pollution episodes

NASA Technical Reports Server (NTRS)

Barnes, J. C.; Bowley, C. J.; Burke, H. H. K.

1979-01-01

A comparative analysis of satellite visible channel imagery and ground based aerosol measurements is carried out for three cases representing a significant pollution episodes based on low surface visibility and high sulfate levels. The feasibility of detecting pollution episodes from space is also investigated using a simulation model. The model results are compared to quantitative information derived from digitized satellite data. The results show that when levels are or = 30 micrograms/cu, a haze pattern that correlates closely with the area of reported low surface visibilities and high micrograms sulfate levels can be detected in satellite visible channel imagery. The model simulation demonstrates the potential of the satellite to monitor the magnitude and areal extent of pollution episodes. Quantitative information on total aerosol amount derived from the satellite digitized data using the atmospheric radiative transfer model agrees well with the results obtained from the ground based measurements.

Solution-grown small-molecule organic semiconductor with enhanced crystal alignment and areal coverage for organic thin film transistors

DOE PAGES

Bi, Sheng; He, Zhengran; Chen, Jihua; ...

2015-07-24

Drop casting of small-molecule organic semiconductors typically forms crystals with random orientation and poor areal coverage, which leads to significant performance variations of organic thin-film transistors (OTFTs). In this study, we utilize the controlled evaporative self-assembly (CESA) method combined with binary solvent system to control the crystal growth. A small-molecule organic semiconductor,2,5-Di-(2-ethylhexyl)-3,6-bis(5"-n-hexyl-2,2',5',2"]terthiophen-5-yl)-pyrrolo[3,4-c]pyrrole-1,4-dione (SMDPPEH), is used as an example to demonstrate the effectiveness of our approach. By optimizing the double solvent ratios, well-aligned SMDPPEH crystals with significantly improved areal coverage were achieved. As a result, the SMDPPEH based OTFTs exhibit a mobility of 1.6 × 10 -2 cm 2/V s, whichmore » is the highest mobility from SMDPPEH ever reported.« less

Reduction in the retinotopic early visual cortex with normal aging and magnitude of perceptual learning.

PubMed

Chang, Li-Hung; Yotsumoto, Yuko; Salat, David H; Andersen, George J; Watanabe, Takeo; Sasaki, Yuka

2015-01-01

Although normal aging is known to reduce cortical structures globally, the effects of aging on local structures and functions of early visual cortex are less understood. Here, using standard retinotopic mapping and magnetic resonance imaging morphologic analyses, we investigated whether aging affects areal size of the early visual cortex, which were retinotopically localized, and whether those morphologic measures were associated with individual performance on visual perceptual learning. First, significant age-associated reduction was found in the areal size of V1, V2, and V3. Second, individual ability of visual perceptual learning was significantly correlated with areal size of V3 in older adults. These results demonstrate that aging changes local structures of the early visual cortex, and the degree of change may be associated with individual visual plasticity. Copyright © 2015 Elsevier Inc. All rights reserved.

Impact of radius and skew angle on areal density in heat assisted magnetic recording hard disk drives

NASA Astrophysics Data System (ADS)

Cordle, Michael; Rea, Chris; Jury, Jason; Rausch, Tim; Hardie, Cal; Gage, Edward; Victora, R. H.

2018-05-01

This study aims to investigate the impact that factors such as skew, radius, and transition curvature have on areal density capability in heat-assisted magnetic recording hard disk drives. We explore a "ballistic seek" approach for capturing in-situ scan line images of the magnetization footprint on the recording media, and extract parametric results of recording characteristics such as transition curvature. We take full advantage of the significantly improved cycle time to apply a statistical treatment to relatively large samples of experimental curvature data to evaluate measurement capability. Quantitative analysis of factors that impact transition curvature reveals an asymmetry in the curvature profile that is strongly correlated to skew angle. Another less obvious skew-related effect is an overall decrease in curvature as skew angle increases. Using conventional perpendicular magnetic recording as the reference case, we characterize areal density capability as a function of recording position.

In-line monitoring of Li-ion battery electrode porosity and areal loading using active thermal scanning - modeling and initial experiment

DOE PAGES

Rupnowski, Przemyslaw; Ulsh, Michael J.; Sopori, Bhushan; ...

2017-08-18

This work focuses on a new technique called active thermal scanning for in-line monitoring of porosity and areal loading of Li-ion battery electrodes. In this technique a moving battery electrode is subjected to thermal excitation and the induced temperature rise is monitored using an infra-red camera. Static and dynamic experiments with speeds up to 1.5 m min -1 are performed on both cathodes and anodes and a combined micro- and macro-scale finite element thermal model of the system is developed. It is shown experimentally and through simulations that during thermal scanning the temperature profile generated in an electrode depends onmore » both coating porosity (or area loading) and thickness. Here, it is concluded that by inverting this relation the porosity (or areal loading) can be determined, if thermal response and thickness are simultaneously measured.« less

In-line monitoring of Li-ion battery electrode porosity and areal loading using active thermal scanning - modeling and initial experiment

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

Rupnowski, Przemyslaw; Ulsh, Michael J.; Sopori, Bhushan

This work focuses on a new technique called active thermal scanning for in-line monitoring of porosity and areal loading of Li-ion battery electrodes. In this technique a moving battery electrode is subjected to thermal excitation and the induced temperature rise is monitored using an infra-red camera. Static and dynamic experiments with speeds up to 1.5 m min -1 are performed on both cathodes and anodes and a combined micro- and macro-scale finite element thermal model of the system is developed. It is shown experimentally and through simulations that during thermal scanning the temperature profile generated in an electrode depends onmore » both coating porosity (or area loading) and thickness. Here, it is concluded that by inverting this relation the porosity (or areal loading) can be determined, if thermal response and thickness are simultaneously measured.« less

In-line monitoring of Li-ion battery electrode porosity and areal loading using active thermal scanning - modeling and initial experiment

NASA Astrophysics Data System (ADS)

Rupnowski, Przemyslaw; Ulsh, Michael; Sopori, Bhushan; Green, Brian G.; Wood, David L.; Li, Jianlin; Sheng, Yangping

2018-01-01

This work focuses on a new technique called active thermal scanning for in-line monitoring of porosity and areal loading of Li-ion battery electrodes. In this technique a moving battery electrode is subjected to thermal excitation and the induced temperature rise is monitored using an infra-red camera. Static and dynamic experiments with speeds up to 1.5 m min-1 are performed on both cathodes and anodes and a combined micro- and macro-scale finite element thermal model of the system is developed. It is shown experimentally and through simulations that during thermal scanning the temperature profile generated in an electrode depends on both coating porosity (or area loading) and thickness. It is concluded that by inverting this relation the porosity (or areal loading) can be determined, if thermal response and thickness are simultaneously measured.

Factors affecting projected Arctic surface shortwave heating and albedo change in coupled climate models.

PubMed

Holland, Marika M; Landrum, Laura

2015-07-13

We use a large ensemble of simulations from the Community Earth System Model to quantify simulated changes in the twentieth and twenty-first century Arctic surface shortwave heating associated with changing incoming solar radiation and changing ice conditions. For increases in shortwave absorption associated with albedo reductions, the relative influence of changing sea ice surface properties and changing sea ice areal coverage is assessed. Changes in the surface sea ice properties are associated with an earlier melt season onset, a longer snow-free season and enhanced surface ponding. Because many of these changes occur during peak solar insolation, they have a considerable influence on Arctic surface shortwave heating that is comparable to the influence of ice area loss in the early twenty-first century. As ice area loss continues through the twenty-first century, it overwhelms the influence of changes in the sea ice surface state, and is responsible for a majority of the net shortwave increases by the mid-twenty-first century. A comparison with the Arctic surface albedo and shortwave heating in CMIP5 models indicates a large spread in projected twenty-first century change. This is in part related to different ice loss rates among the models and different representations of the late twentieth century ice albedo and associated sea ice surface state. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Factors affecting projected Arctic surface shortwave heating and albedo change in coupled climate models

PubMed Central

Holland, Marika M.; Landrum, Laura

2015-01-01

We use a large ensemble of simulations from the Community Earth System Model to quantify simulated changes in the twentieth and twenty-first century Arctic surface shortwave heating associated with changing incoming solar radiation and changing ice conditions. For increases in shortwave absorption associated with albedo reductions, the relative influence of changing sea ice surface properties and changing sea ice areal coverage is assessed. Changes in the surface sea ice properties are associated with an earlier melt season onset, a longer snow-free season and enhanced surface ponding. Because many of these changes occur during peak solar insolation, they have a considerable influence on Arctic surface shortwave heating that is comparable to the influence of ice area loss in the early twenty-first century. As ice area loss continues through the twenty-first century, it overwhelms the influence of changes in the sea ice surface state, and is responsible for a majority of the net shortwave increases by the mid-twenty-first century. A comparison with the Arctic surface albedo and shortwave heating in CMIP5 models indicates a large spread in projected twenty-first century change. This is in part related to different ice loss rates among the models and different representations of the late twentieth century ice albedo and associated sea ice surface state. PMID:26032318

Precipitation areal-reduction factor estimation using an annual-maxima centered approach

USGS Publications Warehouse

Asquith, W.H.; Famiglietti, J.S.

2000-01-01

The adjustment of precipitation depth of a point storm to an effective (mean) depth over a watershed is important for characterizing rainfall-runoff relations and for cost-effective designs of hydraulic structures when design storms are considered. A design storm is the precipitation point depth having a specified duration and frequency (recurrence interval). Effective depths are often computed by multiplying point depths by areal-reduction factors (ARF). ARF range from 0 to 1, vary according to storm characteristics, such as recurrence interval; and are a function of watershed characteristics, such as watershed size, shape, and geographic location. This paper presents a new approach for estimating ARF and includes applications for the 1-day design storm in Austin, Dallas, and Houston, Texas. The approach, termed 'annual-maxima centered,' specifically considers the distribution of concurrent precipitation surrounding an annual-precipitation maxima, which is a feature not seen in other approaches. The approach does not require the prior spatial averaging of precipitation, explicit determination of spatial correlation coefficients, nor explicit definition of a representative area of a particular storm in the analysis. The annual-maxima centered approach was designed to exploit the wide availability of dense precipitation gauge data in many regions of the world. The approach produces ARF that decrease more rapidly than those from TP-29. Furthermore, the ARF from the approach decay rapidly with increasing recurrence interval of the annual-precipitation maxima. (C) 2000 Elsevier Science B.V.The adjustment of precipitation depth of a point storm to an effective (mean) depth over a watershed is important for characterizing rainfall-runoff relations and for cost-effective designs of hydraulic structures when design storms are considered. A design storm is the precipitation point depth having a specified duration and frequency (recurrence interval). Effective depths are often computed by multiplying point depths by areal-reduction factors (ARF). ARF range from 0 to 1, vary according to storm characteristics, such as recurrence interval; and are a function of watershed characteristics, such as watershed size, shape, and geographic location. This paper presents a new approach for estimating ARF and includes applications for the 1-day design storm in Austin, Dallas, and Houston, Texas. The approach, termed 'annual-maxima centered,' specifically considers the distribution of concurrent precipitation surrounding an annual-precipitation maxima, which is a feature not seen in other approaches. The approach does not require the prior spatial averaging of precipitation, explicit determination of spatial correlation coefficients, nor explicit definition of a representative area of a particular storm in the analysis. The annual-maxima centered approach was designed to exploit the wide availability of dense precipitation gauge data in many regions of the world. The approach produces ARF that decrease more rapidly than those from TP-29. Furthermore, the ARF from the approach decay rapidly with increasing recurrence interval of the annual-precipitation maxima.

On buoyancy-driven natural ventilation of a room with a heated floor

NASA Astrophysics Data System (ADS)

Gladstone, Charlotte; Woods, Andrew W.

2001-08-01

The natural ventilation of a room, both with a heated floor and connected to a cold exterior through two openings, is investigated by combining quantitative models with analogue laboratory experiments. The heated floor generates an areal source of buoyancy while the openings allow displacement ventilation to operate. When combined, these produce a steady state in which the air in the room is well-mixed, and the heat provided by the floor equals the heat lost by displacement. We develop a quantitative model describing this process, in which the advective heat transfer through the openings is balanced with the heat flux supplied at the floor. This model is successfully tested with observations from small-scale analogue laboratory experiments. We compare our results with the steady-state flow associated with a point source of buoyancy: for a given applied heat flux, an areal source produces heated air of lower temperature but a greater volume flux of air circulates through the room. We generalize the model to account for the effects of (i) a cooled roof as well as a heated floor, and (ii) an external wind or temperature gradient. In the former case, the direction of the flow through the openings depends on the temperature of the exterior air relative to an averaged roof and floor temperature. In the latter case, the flow is either buoyancy dominated or wind dominated depending on the strength of the pressure associated with the wind. Furthermore, there is an intermediate multiple-solution regime in which either flow regime may develop.

Delineation of areas contributing groundwater to selected receiving surface water bodies for long-term average hydrologic conditions from 1968 to 1983 for Long Island, New York

USGS Publications Warehouse

Misut, Paul E.; Monti,, Jack

2016-10-05

To assist resource managers and planners in developing informed strategies to address nitrogen loading to coastal water bodies of Long Island, New York, the U.S. Geological Survey and the New York State Department of Environmental Conservation initiated a program to delineate a comprehensive dataset of groundwater recharge areas (or areas contributing groundwater), travel times, and outflows to streams and saline embayments on Long Island. A four-layer regional three-dimensional finite-difference groundwater-flow model of hydrologic conditions from 1968 to 1983 was used to provide delineations of 48 groundwater watersheds on Long Island. Sixteen particle starting points were evenly spaced within each of the 4,000- by 4,000-foot model cells that receive water-table recharge and tracked using forward particle-tracking analysis modeling software to outflow zones. For each particle, simulated travel times were grouped by age as follows: less than or equal to 10 years, greater than 10 years and less than or equal to 100 years, greater than 100 years and less than or equal to 1,000 years, and greater than 1,000 years; and simulated ending zones were grouped into 48 receiving water bodies, based on the New York State Department of Environmental Conservation Waterbody Inventory/Priority Waterbodies List. Areal delineation of travel time zones and groundwater contributing areas were generated and a table was prepared presenting the sum of groundwater outflow for each area.

Influence of Climate Oscillations on Extreme Precipitation in Texas

NASA Astrophysics Data System (ADS)

Bhatia, N.; Singh, V. P.; Srivastav, R. K.

2016-12-01

Much research in the field of hydroclimatology is focusing on the impact of climate variability on hydrologic extremes. Recent studies show that the unique geographical location and the enormous areal extent, coupled with extensive variations in climate oscillations, have intensified the regional hydrologic cycle of Texas. The state-wide extreme precipitation events can actually be attributed to sea-surface pressure and temperature anomalies, such as Bermuda High and Jet Streams, which are further triggered by such climate oscillations. This study aims to quantify the impact of five major Atlantic and Pacific Ocean related climate oscillations: (i) Atlantic Multidecadal Oscillation (AMO), (ii) North Atlantic Oscillation (NAO), (iii) Pacific Decadal Oscillation (PDO), (iv) Pacific North American Pattern (PNA), and (v) Southern Oscillation Index (SOI), on extreme precipitation in Texas. Their respective effects will be determined for both climate divisions delineated by the National Climatic Data Centre (NCDC) and climate regions defined by the Köppen Climate Classification System. This study will adopt a weighted correlation approach to attain the robust correlation coefficients while addressing the regionally variable data outliers for extreme precipitation. Further, the variation of robust correlation coefficients across Texas is found to be related to the station elevation, historical average temperature, and total precipitation in the months of extremes. The research will shed light on the relationship between precipitation extremes and climate variability, thus aiding regional water boards in planning, designing, and managing the respective systems as per the future climate change.

Sediment diffusion method improves wastewater nitrogen removal in the receiving lake sediments.

PubMed

Aalto, Sanni L; Saarenheimo, Jatta; Ropponen, Janne; Juntunen, Janne; Rissanen, Antti J; Tiirola, Marja

2018-07-01

Sediment microbes have a great potential to transform reactive N to harmless N 2 , thus decreasing wastewater nitrogen load into aquatic ecosystems. Here, we examined if spatial allocation of the wastewater discharge by a specially constructed sediment diffuser pipe system enhanced the microbial nitrate reduction processes. Full-scale experiments were set on two Finnish lake sites, Keuruu and Petäjävesi, and effects on the nitrate removal processes were studied using the stable isotope pairing technique. All nitrate reduction rates followed nitrate concentrations, being highest at the wastewater-influenced sampling points. Complete denitrification with N 2 as an end-product was the main nitrate reduction process, indicating that the high nitrate and organic matter concentrations of wastewater did not promote nitrous oxide (N 2 O) production (truncated denitrification) or ammonification (dissimilatory nitrate reduction to ammonium; DNRA). Using 3D simulation, we demonstrated that the sediment diffusion method enhanced the contact time and amount of wastewater near the sediment surface especially in spring and in autumn, altering organic matter concentration and oxygen levels, and increasing the denitrification capacity of the sediment. We estimated that natural denitrification potentially removed 3-10% of discharged wastewater nitrate in the 33 ha study area of Keuruu, and the sediment diffusion method increased this areal denitrification capacity on average 45%. Overall, our results indicate that sediment diffusion method can supplement wastewater treatment plant (WWTP) nitrate removal without enhancing alternative harmful processes. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Surface Chemistry in Cobalt Phosphide-Stabilized Lithium-Sulfur Batteries.

PubMed

Zhong, Yiren; Yin, Lichang; He, Peng; Liu, Wen; Wu, Zishan; Wang, Hailiang

2018-01-31

Chemistry at the cathode/electrolyte interface plays an important role for lithium-sulfur batteries in which stable cycling of the sulfur cathode requires confinement of the lithium polysulfide intermediates and their fast electrochemical conversion on the electrode surface. While many materials have been found to be effective for confining polysulfides, the underlying chemical interactions remain poorly understood. We report a new and general lithium polysulfide-binding mechanism enabled by surface oxidation layers of transition-metal phosphide and chalcogenide materials. We for the first time find that CoP nanoparticles strongly adsorb polysulfides because their natural oxidation (forming Co-O-P-like species) activates the surface Co sites for binding polysulfides via strong Co-S bonding. With a surface oxidation layer capable of confining polysulfides and an inner core suitable for conducting electrons, the CoP nanoparticles are thus a desirable candidate for stabilizing and improving the performance of sulfur cathodes in lithium-sulfur batteries. We demonstrate that sulfur electrodes that hold a high mass loading of 7 mg cm -2 and a high areal capacity of 5.6 mAh cm -2 can be stably cycled for 200 cycles. We further reveal that this new surface oxidation-induced polysulfide-binding scheme applies to a series of transition-metal phosphide and chalcogenide materials and can explain their stabilizing effects for lithium-sulfur batteries.

Water-quality conditions and an evaluation of ground- and surface-water sampling programs in the Livermore-Amador Valley, California

USGS Publications Warehouse

Sorenson, S.K.; Cascos, P.V.; Glass, R.L.

1984-01-01

A program to monitor the ground- and surface water quality in the Livermore-Amador Valley has been operated since 1976. As of 1982, this monitoring network consisted of approximately 130 wells, about 100 of which were constructed specifically for this program, and 9 surface water stations. Increased demand on the groundwater for municipal and industrial water supply in the past has caused a decline in water levels and a gradual buildup of salts from natural surface-water recharge and land disposal of treated wastewater from waste treatment plants. Results of this study identify the salt buildup to be the major problem with the groundwater quality. Established water quality objectives for dissolved solids are exceeded in 52 of 130 wells. Concentrations of dissolved nitrate are also in excess of basin objectives and health standards. Water quality in both surface and groundwater is highly variable areally. Magnesium to calcium magnesium bicarbonate groundwater are found in the areas where most of the high volume municipal wells are located. Large areas of sodium bicarbonate water occur in the northern part of the valley. Except for two stations on Arroyo Las Positas which has sodium chloride water, surface water is mixed-cation bicarbonate water. (USGS)

Inverse-collimated proton radiography for imaging thin materials

NASA Astrophysics Data System (ADS)

Freeman, Matthew S.; Allison, Jason; Andrews, Malcolm; Ferm, Eric; Goett, John J.; Kwiatkowski, Kris; Lopez, Julian; Mariam, Fesseha; Marr-Lyon, Mark; Martinez, Michael; Medina, Jason; Medina, Patrick; Merrill, Frank E.; Morris, Chris L.; Murray, Matthew M.; Nedrow, Paul; Neukirch, Levi P.; Prestridge, Katherine; Rigg, Paolo; Saunders, Alexander; Schurman, Tamsen; Tainter, Amy; Trouw, Frans; Tupa, Dale; Tybo, Josh; Vogan-McNeil, Wendy; Wilde, Carl

2017-01-01

Relativistic, magnetically focused proton radiography was invented at Los Alamos National Laboratory using the 800 MeV LANSCE beam and is inherently well-suited to imaging dense objects, at areal densities >20 g cm-2. However, if the unscattered portion of the transmitted beam is removed at the Fourier plane through inverse-collimation, this system becomes highly sensitive to very thin media, of areal densities <100 mg cm-2. Here, this inverse-collimation scheme is described in detail and demonstrated by imaging Xe gas with a shockwave generated by an aluminum plate compressing the gas at Mach 8.8. With a 5-mrad inverse collimator, an areal density change of just 49 mg cm-2 across the shock front is discernible with a contrast-to-noise ratio of 3. Geant4 modeling of idealized and realistic proton transports can guide the design of inverse-collimators optimized for specific experimental conditions and show that this technique performs better for thin targets with reduced incident proton beam emittance. This work increases the range of areal densities to which the system is sensitive to span from ˜25 mg cm-2 to 100 g cm-2, exceeding three orders of magnitude. This enables the simultaneous imaging of a dense system as well as thin jets and ejecta material that are otherwise difficult to characterize with high-energy proton radiography.

Inverse-collimated proton radiography for imaging thin materials.

PubMed

Freeman, Matthew S; Allison, Jason; Andrews, Malcolm; Ferm, Eric; Goett, John J; Kwiatkowski, Kris; Lopez, Julian; Mariam, Fesseha; Marr-Lyon, Mark; Martinez, Michael; Medina, Jason; Medina, Patrick; Merrill, Frank E; Morris, Chris L; Murray, Matthew M; Nedrow, Paul; Neukirch, Levi P; Prestridge, Katherine; Rigg, Paolo; Saunders, Alexander; Schurman, Tamsen; Tainter, Amy; Trouw, Frans; Tupa, Dale; Tybo, Josh; Vogan-McNeil, Wendy; Wilde, Carl

2017-01-01

Relativistic, magnetically focused proton radiography was invented at Los Alamos National Laboratory using the 800 MeV LANSCE beam and is inherently well-suited to imaging dense objects, at areal densities >20 g cm -2 . However, if the unscattered portion of the transmitted beam is removed at the Fourier plane through inverse-collimation, this system becomes highly sensitive to very thin media, of areal densities <100 mg cm -2 . Here, this inverse-collimation scheme is described in detail and demonstrated by imaging Xe gas with a shockwave generated by an aluminum plate compressing the gas at Mach 8.8. With a 5-mrad inverse collimator, an areal density change of just 49 mg cm -2 across the shock front is discernible with a contrast-to-noise ratio of 3. Geant4 modeling of idealized and realistic proton transports can guide the design of inverse-collimators optimized for specific experimental conditions and show that this technique performs better for thin targets with reduced incident proton beam emittance. This work increases the range of areal densities to which the system is sensitive to span from ∼25 mg cm -2 to 100 g cm -2 , exceeding three orders of magnitude. This enables the simultaneous imaging of a dense system as well as thin jets and ejecta material that are otherwise difficult to characterize with high-energy proton radiography.

Porous-Shell Vanadium Nitride Nanobubbles with Ultrahigh Areal Sulfur Loading for High-Capacity and Long-Life Lithium-Sulfur Batteries.

PubMed

Ma, Lianbo; Yuan, Hao; Zhang, Wenjun; Zhu, Guoyin; Wang, Yanrong; Hu, Yi; Zhao, Peiyang; Chen, Renpeng; Chen, Tao; Liu, Jie; Hu, Zheng; Jin, Zhong

2017-12-13

Lithium-sulfur (Li-S) batteries hold great promise for the applications of high energy density storage. However, the performances of Li-S batteries are restricted by the low electrical conductivity of sulfur and shuttle effect of intermediate polysulfides. Moreover, the areal loading weights of sulfur in previous studies are usually low (around 1-3 mg cm -2 ) and thus cannot fulfill the requirement for practical deployment. Herein, we report that porous-shell vanadium nitride nanobubbles (VN-NBs) can serve as an efficient sulfur host in Li-S batteries, exhibiting remarkable electrochemical performances even with ultrahigh areal sulfur loading weights (5.4-6.8 mg cm -2 ). The large inner space of VN-NBs can afford a high sulfur content and accommodate the volume expansion, and the high electrical conductivity of VN-NBs ensures the effective utilization and fast redox kinetics of polysulfides. Moreover, VN-NBs present strong chemical affinity/adsorption with polysulfides and thus can efficiently suppress the shuttle effect via both capillary confinement and chemical binding, and promote the fast conversion of polysulfides. Benefiting from the above merits, the Li-S batteries based on sulfur-filled VN-NBs cathodes with 5.4 mg cm -2 sulfur exhibit impressively high areal/specific capacity (5.81 mAh cm -2 ), superior rate capability (632 mAh g -1 at 5.0 C), and long cycling stability.

Localized and Areally Extensive Alterations in Marathon Valley, Endeavour Crater Rim, Mars

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.; Gellert, Ralf; Van Bommel, Scott; Arvidson, Raymond E.; Clark, Benton C.; Cohen, Barbara A.; Farrand, William H.; Ming, Douglas W.; Schroeder, Christian; Yen, Albert S.;

Fabrication and Deployment Testing of Solar Sail Quadrants for a 20-Meter Solar Sail Ground Test System Demonstration

NASA Technical Reports Server (NTRS)

Laue, Greg; Case, David; Moore, Jim

2005-01-01

A 20-meter Scalable Square Solar Sail (S(sup 4)) System was produced and successfully completed functional vacuum testing in NASA Glenn's Space Power Facility at Plum Brook Station Ohio in May 2005. The S(sup 4) system was designed and developed by ATK Space Systems, and the design and production of the Solar Sails for this system was carried out by SRS Technologies. The S(sup 4) system consists of a central structure with four deployable carbon fiber masts that support four triangular sails. SRS has developed an effective and efficient design for triangular sail quadrants that are supported at three points and provide a flat reflective surface with a high fill factor. This sail design is robust enough for deployments in a one atmosphere, one gravity environment and incorporates several advanced features including adhesiveless seaming of membrane strips, compliant edge borders to allow for film membrane cord strain mismatch without causing wrinkling and low mass (3% of total sail mass) ripstop. This paper will outline some of the sail design and fabrication processes and the mature production, packaging and deployment processes that have been developed. This paper will also detail the successful ambient and vacuum testing of the sails and the ATK spacecraft structure. Based on recent experience and testing, SRS is confidant that high Technology Readiness Level (TRL) 5-6 solar sails in the 40-120-meter size range with areal density in the 4-5 grams per square meters (sail minus structure) range can be produced with existing technology. Additional film production research will lead to further reductions in film thickness to less than 1 micron enabling production of sails with areal densities as low as 2.0 grams per square meters using the current design, resulting in a system areal densities as low as 5.3 grams per square meters (sail and structure). These areal densities are low enough to allow nearly all of the Solar Sail missions that have been proposed by the scientific community. The fundamental technologies required to produce these systems has been demonstrated on the 20-meter S(sup 4) sails that have recently completed ground testing demonstrating a mature and technology suitable for incorporation into future flight validation and future mission. Solar Sails can support NASA's Vision for Space Exploration by allowing communication satellite orbits that can maintain continuous communication with the polar regions of the Moon and Mars and to support solar weather monitoring to provide early warning of solar flares and storms that could threaten the safety of astronauts and other spacecraft.

Possibility of the real-time dynamic strain field monitoring deduced from GNSS data: case study of the 2016 Kumamoto earthquake sequence

NASA Astrophysics Data System (ADS)

Ohta, Y.; Ohzono, M.; Takahashi, H.; Kawamoto, S.; Hino, R.

2017-12-01

A large and destructive earthquake (Mjma 7.3) occurred on April 15, 2016 in Kumamoto region, southwestern Japan. This earthquake was accompanied approximately 32 s later by an M 6 earthquake in central Oita region, which hypocenter located 80 km northeast from the hypocenter of the mainshock of the Kumamoto earthquake. This triggered earthquake also had the many aftershocks in and around the Oita region. It is important to understand how to occur such chain-reacted earthquake sequences. We used the 1Hz dual-frequency phase and range data from GEONET in Kyushu island. The data were processed using GIPSY-OASIS (version 6.4). We adopoted kinematic PPP strategy for the coordinate estimation. The reference GPS satellite orbit and 5 s clock information were obtained using the CODE product. We also applied simple sidereal filter technique for the estimated time series. Based on the obtained 1Hz GNSS time series, we estimated the areal strain and principle strain field using the method of the Shen et al. (1996). For the assessment of the dynamic strain, firstly we calculated the averaged absolute value of areal strain field between 60-85s after the origin time of the mainshock of the Kumamoto earthquake which was used as the "reference" static strain field. Secondly, we estimated the absolute value of areal strain in each time step. Finally, we calculated the strain ratio in each time step relative to the "reference". Based on this procedure, we can extract the spatial and temporal characteristic of the dynamic strain in each time step. Extracted strain ratio clearly shows the spatial and temporal dynamic strain characteristic. When an attention is paid to a region of triggered Oita earthquake, the timing of maximum dynamic strain ratio in the epicenter just corresponds to the origin time of the triggered event. It strongly suggested that the large dynamic strain may trigger the Oita event. The epicenter of the triggered earthquake located within the geothermal region. In the geothermal region, the crustal materials are more sensitive to stress perturbations, and the earthquakes are more easily triggered compared with other typical regions. Our result also suggested that the real-time strain field monitoring may be useful information for the understanding of the possibility of the remotely triggered earthquake in the future.

Loop and void damage during heavy ion irradiation on nanocrystalline and coarse grained tungsten: Microstructure, effect of dpa rate, temperature, and grain size

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

El-Atwani, O.; Esquivel, E.; Efe, M.

Displacement damage, through heavy ion irradiation was studied on two tungsten grades (coarse grained tungsten (CGW) and nanocrystalline and ultrafine grained tungsten (NCW)) using different displacement per atom rates and different irradiation temperatures (RT and 1050 K). Percentage of <111> and <100> type loops at the irradiation conditions was determined. Irradiation damage in the microstructure was quantified using average loop areas and densities (method A) and loop areal fraction in the grain matrices under 2-beam diffraction conditions (method B). Average values of <111> and <100> loops were calculated from method A. Loop coalescence was shown to occur for CGW atmore » 0.25 dpa. Using both methods of quantifying microstructural damage, no effect of dpa rate was observed and damage in CGW was shown to be the same at RT and 1050 K. Swelling from voids observed at 1050 K was quantified. The loop damage in NCW was compared to CGW at the same diffraction and imaging conditions. NCW was shown to possess enhanced irradiation resistance at RT regarding loop damage and higher swelling resistance at 1050 K compared to CGW. For irradiation at 1050 K, the NCW was shown to have a similar defect densities to the CGW which is attributed to higher surface effects in the CGW, vacancy loop growth to voids and a better sink efficiency in the CGW deduced from the vacancy distribution profiles from Kinetic Monte Carlo simulations. Loop density and swelling was shown to have similar values in grains sizes that range from 80-600 nm. No loop or void denuded zones occurred at any of the irradiation conditions. This work has a collection of experiments and conclusions that are of vital importance to materials and nuclear communities.« less

Loop and void damage during heavy ion irradiation on nanocrystalline and coarse grained tungsten: Microstructure, effect of dpa rate, temperature, and grain size

DOE PAGES

El-Atwani, O.; Esquivel, E.; Efe, M.; ...

2018-02-20

Displacement damage, through heavy ion irradiation was studied on two tungsten grades (coarse grained tungsten (CGW) and nanocrystalline and ultrafine grained tungsten (NCW)) using different displacement per atom rates and different irradiation temperatures (RT and 1050 K). Percentage of <111> and <100> type loops at the irradiation conditions was determined. Irradiation damage in the microstructure was quantified using average loop areas and densities (method A) and loop areal fraction in the grain matrices under 2-beam diffraction conditions (method B). Average values of <111> and <100> loops were calculated from method A. Loop coalescence was shown to occur for CGW atmore » 0.25 dpa. Using both methods of quantifying microstructural damage, no effect of dpa rate was observed and damage in CGW was shown to be the same at RT and 1050 K. Swelling from voids observed at 1050 K was quantified. The loop damage in NCW was compared to CGW at the same diffraction and imaging conditions. NCW was shown to possess enhanced irradiation resistance at RT regarding loop damage and higher swelling resistance at 1050 K compared to CGW. For irradiation at 1050 K, the NCW was shown to have a similar defect densities to the CGW which is attributed to higher surface effects in the CGW, vacancy loop growth to voids and a better sink efficiency in the CGW deduced from the vacancy distribution profiles from Kinetic Monte Carlo simulations. Loop density and swelling was shown to have similar values in grains sizes that range from 80-600 nm. No loop or void denuded zones occurred at any of the irradiation conditions. This work has a collection of experiments and conclusions that are of vital importance to materials and nuclear communities.« less

Hybrids of Solar Sail, Solar Electric, and Solar Thermal Propulsion for Solar-System Exploration

NASA Technical Reports Server (NTRS)

Wilcox, Brian H.

2012-01-01

Solar sails have long been known to be an attractive method of propulsion in the inner solar system if the areal density of the overall spacecraft (S/C) could be reduced to approx.10 g/sq m. It has also long been recognized that the figure (precise shape) of useful solar sails needs to be reasonably good, so that the reflected light goes mostly in the desired direction. If one could make large reflective surfaces with reasonable figure at an areal density of approx.10 g/sq m, then several other attractive options emerge. One is to use such sails as solar concentrators for solar-electric propulsion. Current flight solar arrays have a specific output of approx. 100W/kg at 1 Astronomical Unit (AU) from the sun, and near-term advances promise to significantly increase this figure. A S/C with an areal density of 10 g/sq m could accelerate up to 29 km/s per year as a solar sail at 1 AU. Using the same sail as a concentrator at 30 AU, the same spacecraft could have up to approx. 45 W of electric power per kg of total S/C mass available for electric propulsion (EP). With an EP system that is 50% power-efficient, exhausting 10% of the initial S/C mass per year as propellant, the exhaust velocity is approx. 119 km/s and the acceleration is approx. 12 km/s per year. This hybrid thus opens attractive options for missions to the outer solar system, including sample-return missions. If solar-thermal propulsion were perfected, it would offer an attractive intermediate between solar sailing in the inner solar system and solar electric propulsion for the outer solar system. In the example above, both the solar sail and solar electric systems don't have a specific impulse that is near-optimal for the mission. Solar thermal propulsion, with an exhaust velocity of the order of 10 km/s, is better matched to many solar system exploration missions. This paper derives the basic relationships between these three propulsion options and gives examples of missions that might be enabled by such hybrids.

Geological-morphological description of the Ishtar Terra (photomap of the Venusian surface sheet B-5)

NASA Technical Reports Server (NTRS)

Sukhanov, A. L.; Pronin, A. A.; Tyuflin, Y. S.; Ostrovskiy, M. V.; Kotelnikov, V. A.; Rzhiga, O. N.; Petrov, G. I.; Sidorenko, A. I.; Aleksandrov, Y. N.; Zakharov, A. I.

1986-01-01

The main part of the Ishtar Terra east of the Maxwell Montes is covered with systems of areal dislocations of several directions, which are called Parquet. According to the structural patterns these may be divided into: (1) the central stable block; (2) the lesser peripheral blocks separated from the central one by gaps and grabens; (3) the zones of mobilized parquet, whose substance flowed downward at an incline in the directions away from the central block in the form of plastic flows; and (4) the partially parqueted lava sheets. The Maxwell Montes were formed as a result of the collision between the central parquet block and the Lakshmi Planum.

Neutron Spectroscopy on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Knauer, J. P.

2012-10-01

The performance of cryogenic fuel implosion experiments in progress at the National Ignition Facility (NIF) is measured by an experimental threshold factorfootnotetextM. J. Edwards et al., Phys. Plasmas 18, 051003 (2011). (ITFX) and a generalized Lawson Criterion.footnotetextC. D. Zhou and R. Betti, Phys. Plasmas 15, 102707 (2008); P. Y. Chang et al., Phys. Rev. Lett. 104, 135002 (2010); and R. Betti et al., Phys. Plasmas 17, 058102 (2010). The ITFX metric is determined by the fusion yield and the areal density of an assembled deuterium-tritium (DT) fuel mass. Typical neutron yields from NIF implosions are greater than 10^14 allowing the neutron energy spectrum to be measured with unprecedented precision. A NIF spectrum is composed of neutrons created by fusion (DT, DD, and TT reactions) and neutrons scattered by the dense, cold fuel layer. Neutron scattering is used to determine the areal density of a NIF implosion and is measured along four lines of sight by two neutron time-of-flight detectors, a neutron imaging system, and the magnetic recoil spectrometer. An accurate measurement of the instrument response function for these detectors allows for the routine production of neutron spectra showing DT fuel areal densities up to 1.3 g/cm^2. Spectra over neutron energies of 10 to 17 MeV show areal-density asymmetries of 20% that are inconsistent with simulations. New calibrations and analyses have expended the spectral coverage down to energies less than the deuterium backscatter edge (1.5 MeV for 14 MeV neutrons). These data and analyses are presented along with a compilation of other nuclear diagnostic data that show a larger-than-expected variation in the areal density over the cold fuel mass. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No DE-FC52-08NA28302. In collaboration with NIC.

Changes in the areal extents of the Athabasca River, Birch River, and Cree Creek Deltas, 1950-2014, Peace-Athabasca Delta, Canada

NASA Astrophysics Data System (ADS)

Timoney, Kevin; Lee, Peter

2016-04-01

Deltas form where riverborne sediment accumulates at the interface of river mouths and their receiving water bodies. Their areal extent is determined by the net effect of processes that increase their extent, such as sediment accumulation, and processes that decrease their extent, such as erosion and subsidence. Through sequential mapping and construction of river discharge and sediment histories, this study examined changes in the subaerial extents of the Cree Creek and Athabasca River Deltas (both on the Athabasca River system) and the Birch River Delta in northern Canada over the period 1950-2014. The purpose of the study was to determine how, when, and why the deltas changed in areal extent. Temporal growth patterns were similar across the Athabasca and Birch River systems indicative of a climatic signal. Little or no areal growth occurred from 1950 to 1968; moderate growth occurred between 1968 and the early to mid-1980s; and rapid growth occurred between 1992 and 2012. Factors that affected delta progradation included dredging, sediment supply, isostatic drowning, delta front bathymetry, sediment capture efficiency, and storms. In relation to sediment delivered, areal growth rates were lowest in the Athabasca Delta, intermediate in the Birch Delta, and highest in the Cree Creek Delta. Annual sediment delivery is increasing in the Cree Creek Delta; there were no significant trends in annual sediment delivery in the Birch and Athabasca Deltas. There was a lag of up to several years between sediment delivery events and progradation. Periods of delta progradation were associated with low water levels of the receiving basins. Predicted climate-change driven declines in river discharge and lake levels may accelerate delta progradation in the region. In the changing ecosystems of northeastern Alberta, inadequate monitoring of vegetation, landforms, and sediment regimes hampers the elucidation of the nature, rate, and causality of ecosystem changes.

Satellite derived estimates of forest leaf area index in South-west Western Australia are not tightly coupled to inter-annual variations in rainfall: implications for groundwater decline in a drying climate.

NASA Astrophysics Data System (ADS)

Smettem, Keith; Waring, Richard; Callow, Nik; Wilson, Melissa; Mu, Qiaozhen

2013-04-01

There is increasing concern that widespread forest decline could occur in regions of the world where droughts are predicted to increase in frequency and severity as a result of climate change. Ecological optimality proposes that the long term average canopy size of undisturbed perennial vegetation is tightly coupled to climate. The average annual leaf area index (LAI) is an indicator of canopy cover and the difference between the annual maximum and minimum LAI is an indicator of annual leaf turnover. In this study we analysed satellite-derived estimates of monthly LAI across forested coastal catchments of South-west Western Australia over a 12 year period (2000-2011) that included the driest year on record for the last 60 years. We observed that over the 12 year study period, the spatial pattern of average annual satellite-derived LAI values was linearly related to mean annual rainfall. However, inter-annual changes to LAI in response to changes in annual rainfall were far less than expected from the long-term LAI-rainfall trend. This buffered response was investigated using a physiological growth model and attributed to availability of deep soil moisture and/or groundwater storage. The maintenance of high LAIs may be linked to a long term decline in areal average underground water storage storage and diminished summer flows, with a trend towards more ephemeral flow regimes.

Nanoscale modeling for ultrathin liquid films: Spreading and coupled layering

NASA Astrophysics Data System (ADS)

Phillips, David Michael

The hard disk drive (HDD) industry is currently experiencing a compound annual growth rate of 100% for the areal density. Current production drives have an areal density of 80 Gbit in-2, and drives with an areal density of 100 Gbit in-2 have been recently demonstrated. While much of this growth has been fueled by the development of new read/write heads, some of this gain was achieved by reducing the spacing between the heads and the magnetic media. This in turn reduces the spacing at the head-disk interface (HDI). The HDI in a HDD system consists of a slider, which contains the read/write heads, flying over the disk surface on an air bearing. The current designed separation distance, or fly height, is less than 10 nm. This spacing is expected to reduce to a mere 5 nm within the next few years. With the reduced fly height, intermittent contacts at the HDI become more probable. Only a thin lubricant film of perfluoropolyether (PFPE) and a sputtered carbon overcoat on the disk surface protect the slider and the stored data from mechanical and thermal damage. The PFPE film is quite thin, with a thickness of less than 2 nm or about a monolayer of molecules. During an HDI contact, the PFPE film is considered sacrificial and is often depleted in the contact area. In order to maintain adequate protection for the disk surface, PFPE molecules from the surrounding film must replenish the depleted area. This replenishment ability directly opposes the requirement that the PFPE film must not spin-off of the disk surface due to the disk rotation rate, which is as high as 10,000 RPM in current drives. To balance the PFPE films to sufficiently meet both requirements, HDD manufacturers functionalized the endgroups of the PFPE molecules to allow some portion of the lubricant film to reversibly bond with the disk overcoat. The result is a lubricant film that has a slower replenishment but does not spin-off. The work presented here focuses on the replenishment ability of thin films of liquid PFPE. The experimental analogue of replenishment is the one-dimensional spreading analysis. PFPEs with functional endgroups demonstrated coupled molecular layering and dewetting phenomena during the spreading analysis, while PFPEs with nonfunctional endgroups did not. All of the PFPE thin films spread via a diffusive process and had diffusion coefficients that depended on the local film thickness. A theoretical analysis is presented here for both the governing equation and the disjoining pressure driving force for the PFPE thin film spreading. For PFPEs with non-functional endgroups, a reasonable analysis is performed on the diffusion coefficient for two classes of film: submonolayer and multilayer. The diffusion coefficient of PFPEs with functional endgroups are qualitatively linked to the gradient of the film disjoining pressure. To augment this theory, both lattice-based and off-lattice Monte Carlo simulations are conducted for PFPE film models. The lattice-based model shows the existence of a critical functional endgroup interaction strength. It is also used to study the break-up of molecular layers for a spreading film via a fractal analysis. The off-lattice model is used to calculate the anisotropic pressure tensor for the model PFPE thin film and subsequently the film disjoining pressure. The model also qualitatively analyzes of the self diffusion in the film.

New World Vistas: New Models of Computation Lattice Based Quantum Computation

DTIC Science & Technology

1996-07-25

ro ns Eniac (18,000 vacuum tubes) UNIVAC II (core memory) Digital Devices magnetostrictive delay line Intel 1103 integrated circuit IBM 3340 disk...in areal size of a bit for the last fifty years since the 1946 Eniac computer. 1 Planned Research I propose to consider the feasibility of implement...tech- nology. Fiqure 1 is a log-linear plot of data for the areal size of a bit over the last fifty years (from 18,000 bits in the 1946 Eniac computer

Effect of solar-cell junction geometry on open-circuit voltage

NASA Technical Reports Server (NTRS)

Weizer, V. G.; Godlewski, M. P.

1985-01-01

Simple analytical models have been found that adequately describe the voltage behavior of both the stripe junction and dot junction grating cells as a function of junction area. While the voltage in the former case is found to be insensitive to junction area reduction, significant voltage increases are shown to be possible for the dot junction cell. With regard to cells in which the junction area has been increased in a quest for better performance, it was found that (1) texturation does not affect the average saturation current density J0, indicating that the texturation process is equivalent to a simple extension of junction area by a factor of square root of 3 and (2) the vertical junction cell geometry produces a sizable decrease in J0 that, unfortunately, is more than offset by the effects of attendant areal increases.

Integrated Vertical Bloch Line (VBL) memory

NASA Technical Reports Server (NTRS)

Katti, R. R.; Wu, J. C.; Stadler, H. L.

1991-01-01

Vertical Bloch Line (VBL) Memory is a recently conceived, integrated, solid state, block access, VLSI memory which offers the potential of 1 Gbit/sq cm areal storage density, data rates of hundreds of megabits/sec, and submillisecond average access time simultaneously at relatively low mass, volume, and power values when compared to alternative technologies. VBLs are micromagnetic structures within magnetic domain walls which can be manipulated using magnetic fields from integrated conductors. The presence or absence of BVL pairs are used to store binary information. At present, efforts are being directed at developing a single chip memory using 25 Mbit/sq cm technology in magnetic garnet material which integrates, at a single operating point, the writing, storage, reading, and amplification functions needed in a memory. The current design architecture, functional elements, and supercomputer simulation results are described which are used to assist the design process.

Carbon coated textiles for flexible energy storage

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

Jost, Kristy; Perez, Carlos R.; McDonough, John K.

This paper describes a flexible and lightweight fabric supercapacitor electrode as a possible energy source in smart garments. We examined the electrochemical behavior of porous carbon materials impregnated into woven cotton and polyester fabrics using a traditional printmaking technique (screen printing). The porous structure of such fabrics makes them attractive for supercapacitor applications that need porous films for ion transfer between electrodes. We used cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy to study the capacitive behaviour of carbon materials using nontoxic aqueous electrolytes including sodium sulfate and lithium sulfate. Electrodes coated with activated carbon (YP17) and tested at ~0.25more » A·g⁻¹ achieved a high gravimetric and areal capacitance, an average of 85 F·g⁻¹ on cotton lawn and polyester microfiber, both corresponding to ~0.43 F·cm⁻².« less

Carbon coated textiles for flexible energy storage

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

Jost, Kristy; Perez, Carlos O; Mcdonough, John

This paper describes a flexible and lightweight fabric supercapacitor electrode as a possible energy source in smart garments. We examined the electrochemical behavior of porous carbon materials impregnated into woven cotton and polyester fabrics using a traditional printmaking technique (screen printing). The porous structure of such fabrics makes them attractive for supercapacitor applications that need porous films for ion transfer between electrodes. We used cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy to study the capacitive behaviour of carbon materials using nontoxic aqueous electrolytes including sodium sulfate and lithium sulfate. Electrodes coated with activated carbon (YP17) and tested at 0.25more » A$g1 achieved a high gravimetric and areal capacitance, an average of 85 F$g1 on cotton lawn and polyester microfiber, both corresponding to 0.43 F$cm2.« less

All-Printed, Self-Aligned Carbon Nanotube Thin-Film Transistors on Imprinted Plastic Substrates.

PubMed

Song, Donghoon; Zare Bidoky, Fazel; Hyun, Woo Jin; Walker, S Brett; Lewis, Jennifer A; Frisbie, C Daniel

2018-05-09

We present a self-aligned process for printing thin-film transistors (TFTs) on plastic with single-walled carbon nanotube (SWCNT) networks as the channel material. The SCALE (self-aligned capillarity-assisted lithography for electronics) process combines imprint lithography with inkjet printing. Specifically, inks are jetted into imprinted reservoirs, where they then flow into narrow device cavities due to capillarity. Here, we incorporate a composite high- k gate dielectric and an aligned conducting polymer gate electrode in the SCALE process to enable a smaller areal footprint than prior designs that yields low-voltage SWCNT TFTs with average p-type carrier mobilities of 4 cm 2 /V·s and ON/OFF current ratios of 10 4 . Our work demonstrates the promising potential of the SCALE process to fabricate SWCNT-based TFTs with favorable I- V characteristics on plastic substrates.

Evaluation of Thermal Control Coatings for Flexible Ceramic Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius; Carroll, Carol; Smith, Dane; Guzinski, Mike; Marschall, Jochen; Pallix, Joan; Ridge, Jerry; Tran, Duoc

1997-01-01

This report summarizes the evaluation and testing of high emissivity protective coatings applied to flexible insulations for the Reusable Launch Vehicle technology program. Ceramic coatings were evaluated for their thermal properties, durability, and potential for reuse. One of the major goals was to determine the mechanism by which these coated blanket surfaces become brittle and try to modify the coatings to reduce or eliminate embrittlement. Coatings were prepared from colloidal silica with a small percentage of either SiC or SiB6 as the emissivity agent. These coatings are referred to as gray C-9 and protective ceramic coating (PCC), respectively. The colloidal solutions were either brushed or sprayed onto advanced flexible reusable surface insulation blankets. The blankets were instrumented with thermocouples and exposed to reentry heating conditions in the Ames Aeroheating Arc Jet Facility. Post-test samples were then characterized through impact testing, emissivity measurements, chemical analysis, and observation of changes in surface morphology. The results show that both coatings performed well in arc jet tests with backface temperatures slightly lower for the PCC coating than with gray C-9. Impact testing showed that the least extensive surface destruction was experienced on blankets with lower areal density coatings.

Laser Scanning on Road Pavements: A New Approach for Characterizing Surface Texture

PubMed Central

Bitelli, Gabriele; Simone, Andrea; Girardi, Fabrizio; Lantieri, Claudio

2012-01-01

The surface layer of road pavement has a particular importance in relation to the satisfaction of the primary demands of locomotion, such as security and eco-compatibility. Among those pavement surface characteristics, the “texture” appears to be one of the most interesting with regard to the attainment of skid resistance. Specifications and regulations, providing a wide range of functional indicators, act as guidelines to satisfy the performance requirements. This paper describes an experiment on the use of laser scanner techniques on various types of asphalt for texture characterization. The use of high precision laser scanners, such as the triangulation types, is proposed to expand the analysis of road pavement from the commonly and currently used two-dimensional method to a three-dimensional one, with the aim of extending the range of the most important parameters for these kinds of applications. Laser scanners can be used in an innovative way to obtain information on areal surface layer through a single measurement, with data homogeneity and representativeness. The described experience highlights how the laser scanner is used for both laboratory experiments and tests in situ, with a particular attention paid to factors that could potentially affect the survey. PMID:23012535

Microzooplankton biomass distribution in Terra Nova Bay, Ross Sea (Antarctica)

NASA Astrophysics Data System (ADS)

Fonda Umani, S.; Monti, M.; Nuccio, C.

1998-11-01

This work describes the spatial and vertical distribution of microzooplankton (20-200 μm) abundance and biomass of the upper layers (0-100 m), collected during the first oceanographic Italian expedition in Antarctica (1987/1988) in Terra Nova Bay (Ross Sea). Biomass was estimated by using biovolume calculations and literature conversion factors. Sampling was carried out at three depths, surface, 50 and 100 m. The dominant taxa were made up of tintinnid ciliates, ciliates other than tintinnids, larvae of micrometazoa and heterotrophic dinoflagellates. The abundance of the total microplankton fraction had its absolute maximum in the center of Terra Nova Bay at the surface with 31 042 ind. dm -3. The areal and vertical distribution of heterotrophic microplankton biomass differs from that of abundance. On the basis of hydrological conditions, phytoplankton composition and biomass and microzooplankton biomass and structure it is possible to identify three groups of stations: 1—northern coastal stations (intermediate chlorophyll maxima, microphytoplankton prevalence, low microzooplankton biomass); 2—central stations (high surface chlorophyll, nanoplankton prevalence, high abundance of microzooplankton); 3—northern stations (deeper pycnocline, nanoplankton prevalence, high microzooplankton biomass at intermediate depths).

Pāhoehoe flow cooling, discharge, and coverage rates from thermal image chronometry

USGS Publications Warehouse

Dehn, Jonathan; Hamilton, Christopher M.; Harris, A. J. L.; Herd, Richard A.; James, M.R.; Lodato, Luigi; Steffke, Andrea

2007-01-01

Theoretically- and empirically-derived cooling rates for active pāhoehoe lava flows show that surface cooling is controlled by conductive heat loss through a crust that is thickening with the square root of time. The model is based on a linear relationship that links log(time) with surface cooling. This predictable cooling behavior can be used assess the age of recently emplaced sheet flows from their surface temperatures. Using a single thermal image, or image mosaic, this allows quantification of the variation in areal coverage rates and lava discharge rates over 48 hour periods prior to image capture. For pāhoehoe sheet flow at Kīlauea (Hawai`i) this gives coverage rates of 1–5 m2/min at discharge rates of 0.01–0.05 m3/s, increasing to ∼40 m2/min at 0.4–0.5 m3/s. Our thermal chronometry approach represents a quick and easy method of tracking flow advance over a three-day period using a single, thermal snap-shot.

System-morphological approach: Another look at morphology research and geomorphological mapping

NASA Astrophysics Data System (ADS)

Lastochkin, Alexander N.; Zhirov, Andrey I.; Boltramovich, Sergei F.

2018-02-01

A large number of studies require a clear and unambiguous morphological basis. For over thirty years, Russian scientists have been applying a system-morphological approach for the Arctic and Antarctic research, ocean floor investigation, for various infrastructure construction projects (oil and gas, sports, etc.), in landscape and environmental studies. This article is a review aimed to introduce this methodological approach to the international scientific community. The details of the methods and techniques can be found in a series of earlier papers published in the Russian language in 1987-2016. The proposed system-morphological approach includes: 1) partitioning of the Earth surface, i.e. precise identification of linear, point, and areal elements of topography considered as a two-dimensional surface without any geological substance; 2) further identification of larger formations: geomorphological systems and regions; 3) analysis of structural relations and symmetry of topography; and 4) various dynamic (litho- and glaciodynamic, tectonic, etc.) interpretations of the observed morphology. This method can be used to study the morphology of the surface topography as well as less accessible interfaces such as submarine and subglacial ones.

A versatile optical profilometer based on conoscopic holography sensors for acquisition of specular and diffusive surfaces in artworks

NASA Astrophysics Data System (ADS)

Gaburro, Nicola; Marchioro, Giacomo; Daffara, Claudia

2017-07-01

Surface metrology of artworks requires the design of suitable devices for in-situ non-destructive measurement together with reliable procedures for an effective analysis of such non-engineered variegate objects. To advance the state-of-the-art it has been implemented a versatile optical micro-profilometry taking advantage of the adapt- ability of conoscopic holography sensors, able to operate with irregular shapes and composite materials (diffusive, specular, and polychrome) of artworks. The scanning technique is used to obtain wide field and high spatially resolved areal profilometry. The prototype has a modular scheme based on a set of conoscopic sensors, extending the typical design based on a scanning stage and a single probe with a limited bandwidth, thus allowing the collection of heights data from surface with different scales and materials with variegate optical response. The system was optimized by characterizing the quality of the measurement with the probes triggered in continuous scanning modality. The results obtained on examples of cultural heritage objects (2D paintings, 3D height-relief) and materials (pictorial, metallic) demonstrate the versatility of the implemented device.

Simulation of gas phase transport of carbon-14 at Yucca Mountain, Nevada, USA

USGS Publications Warehouse

Lu, N.; Ross, B.

1994-01-01

We have simulated gas phase transport of Carbon-14 at Yucca Mountain, Nevada. Three models were established to calculate travel time of Carbon-14 from the potential repository to the mountain surface: a geochemical model for retardation factors, a coupled gas-flow and heat transfer model for temperature and gas flow fields, and a particle tracker for travel time calculation. The simulations used three parallel, east-west cross-sections that were taken from the Sandia National Laboratories Interactive Graphics Information System (IGIS). Assuming that the repository is filled with 30- year-old waste at an initial areal power density of 57 kw/acre, we found that repository temperatures remain above 60??C for more than 10,000 years. For a tuff permeability of 10-7 cm2, Carbon-14 travel times to the surface are mostly less than 1,000 years, for particles starting at any time within the first 10,000 years. If the tuff permeability is 10-8 cm2, however, Carbon- 14 travel times to the surface range from 3,000 to 12,000 years, for particle starting within the 10,000 years.

The potential of freshwater macroalgae as a biofuels feedstock and the influence of nutrient availability on freshwater macroalgal biomass production

NASA Astrophysics Data System (ADS)

Yun, Jin-Ho

Extensive efforts have been made to evaluate the potential of microalgae as a biofuel feedstock during the past 4-5 decades. However, filamentous freshwater macroalgae have numerous characteristics that favor their potential use as an alternative algal feedstock for biofuels production. Freshwater macroalgae exhibit high rates of areal productivity, and their tendency to form dense floating mats on the water surface imply significant reductions in harvesting and dewater costs compared to microalgae. In Chapter 1, I reviewed the published literature on the elemental composition and energy content of five genera of freshwater macroalgae. This review suggested that freshwater macroalgae compare favorably with traditional bio-based energy sources, including terrestrial residues, wood, and coal. In addition, I performed a semi-continuous culture experiment using the common Chlorophyte genus Oedogonium to investigate whether nutrient availability can influence its higher heating value (HHV), productivity, and proximate analysis. The experimental study suggested that the most nutrient-limited growth conditions resulted in a significant increase in the HHV of the Oedogonium biomass (14.4 MJ/kg to 16.1 MJ/kg). Although there was no significant difference in productivity between the treatments, the average dry weight productivity of Oedogonium (3.37 g/m2/day) was found to be much higher than is achievable with common terrestrial plant crops. Although filamentous freshwater macroalgae, therefore, have significant potential as a renewable source of bioenergy, the ultimate success of freshwater macroalgae as a biofuel feedstock will depend upon the ability to produce biomass at the commercial-scale in a cost-effective and sustainable manner. Aquatic ecology can play an important role to achieve the scale-up of algal crop production by informing the supply rates of nutrients to the cultivation systems, and by helping to create adaptive production systems that are resilient to environmental change. In Chapter 2, I performed a review and an analysis of data from the published literature on the large-cultivation of freshwater macroalgae. This study revealed that the large-scale cultivation of freshwater macroalgae is feasible at relatively low cost using currently available technologies such as the Algal Turf Scrubber system (ATS). In addition, graphical analyses of published data obtained from ATS systems of varying sizes in operation worldwide revealed that both macroalgal biomass productivity and nutrient removal rates are hyperbolically related to the areal loading rates of both total nitrogen and total phosphorus. An assessment of the limited existing literature on carbon dioxide amendments suggested that the effectiveness and need for CO2 supplementation of macroalgal production systems like the ATS has not yet been conclusively demonstrated. Overall, this thesis demonstrates that filamentous freshwater macroalgae have great potential as a feedstock for both liquid and solid fuels, especially if nutrient-rich wastewater can be used as the supply of water and mineral nutrients. In addition, this thesis highlights the importance of studying the algal cultivation conditions that influence trade-offs between nutrient loading, biomass productivity, and biomass energy content. In particular, the hyperbolic relationship between algal biomass productivity and the areal loading rates of both total nitrogen and total phosphorus should provide critical insight when considering the production costs of macroalgal biomass at the commercial-scale.

Influencing factors on the size uniformity of self-assembled SiGe quantum rings grown by molecular beam epitaxy.

PubMed

Cui, J; Lv, Y; Yang, X J; Fan, Y L; Zhong, Z; Jiang, Z M

2011-03-25

The size uniformity of self-assembled SiGe quantum rings, which are formed by capping SiGe quantum dots with a thin Si layer, is found to be greatly influenced by the growth temperature and the areal density of SiGe quantum dots. Higher growth temperature benefits the size uniformity of quantum dots, but results in low Ge concentration as well as asymmetric Ge distribution in the dots, which induces the subsequently formed quantum rings to be asymmetric in shape or even broken somewhere in the ridge of rings. Low growth temperature degrades the size uniformity of quantum dots, and thus that of quantum rings. A high areal density results in the expansion and coalescence of neighboring quantum dots to form a chain, rather than quantum rings. Uniform quantum rings with a size dispersion of 4.6% and an areal density of 7.8×10(8) cm(-2) are obtained at the optimized growth temperature of 640°C.

Structure, mechanical and tribological properties of TiSiC films deposited by magnetron sputtering segment target

NASA Astrophysics Data System (ADS)

Jiang, Jinlong; He, Kaichen; He, XingXing; Huang, Hao; Pang, Xianjuan; Wei, Zhiqiang

2017-12-01

In this work, the TiSiC films were deposited by magnetron sputtering segment target with various areal ratio of Ti80Si20 to C. The effects of segment target component on the structure, mechanical and tribological properties of the films were investigated. The results revealed that the deposited films exhibited a structural transform from a cubic TiC structure to a nanocomposite structure with nanocrystalline TiC in a-C:Si matrix, and finally x-ray amorphous structures with decreasing areal ratio of Ti80Si20 to C. The TiSiC film deposited at the Ti80Si20:C areal ratio of 7:7 showed superior mechanical and tribological properties such as high hardness (18.6 Gpa), good scratch resistant (46 N), low friction coefficient (0.2) and low wear rate (8.6  ×  10-7 mm3 Nm-1), which suggests that it is a promising candidate for the protective films.

Positron Radiography of Ignition-Relevant ICF Capsules

NASA Astrophysics Data System (ADS)

Williams, Jackson; Chen, Hui; Field, John; Landen, Nino; Strozzi, David

2017-10-01

X-ray and neutron radiography are currently used to infer residual ICF shell and fuel asymmetries and areal density non-uniformities near and at peak compression that can impede ignition. Charged particles offer an alternative probe source that, in principle, are capable of radiographing the shell shape and areal density at arbitrary times, even in the presence of large x-ray self-emission. Laser-generated positrons are evaluated as a source to radiograph ICF capsules where current ultraintense laser facilities are capable of producing 2 ×1012 relativistic positrons in a narrow energy bandwidth and short duration. Monte Carlo simulations suggest that both the areal density and shell radius can be reconstructed for ignition-relevant capsules conditions between 0.002-2 g/cm2, and that this technique might be better suited to direct-drive. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the LDRD Program under project tracking code 17-ERD-010.

Use of 41Ar production to measure ablator areal density in NIF beryllium implosions

DOE PAGES

Wilson, Douglas Carl; Cassata, W. S.; Sepke, S. M.; ...

2017-02-06

For the first time, 41Ar produced by the (n,Υ) reaction from 40Ar in the beryllium shell of a DT filled Inertial Confinement Fusion capsule has been measured. Ar is co-deposited with beryllium in the sputter deposition of the capsule shell. Combined with a measurement of the neutron yield, the radioactive 41Ar then quantifies the areal density of beryllium during the DT neutron production. Here, the measured 1.15 ± 0.17 × 10 +8 atoms of 41Ar are 2.5 times that from the best post-shot calculation, suggesting that the Ar and Be areal densities are correspondingly higher than those calculated. Possible explanationsmore » are that (1) the beryllium shell is compressed more than calculated, (2) beryllium has mixed into the cold DT ice, or more likely (3) less beryllium is ablated than calculated. Since only one DT filled beryllium capsule has been fielded at NIF, these results can be confirmed and expanded in the future.« less

Pie-like electrode design for high-energy density lithium–sulfur batteries

PubMed Central

Li, Zhen; Zhang, Jin Tao; Chen, Yu Ming; Li, Ju; Lou, Xiong Wen (David)

2015-01-01

Owing to the overwhelming advantage in energy density, lithium–sulfur (Li–S) battery is a promising next-generation electrochemical energy storage system. Despite many efforts in pursuing long cycle life, relatively little emphasis has been placed on increasing the areal energy density. Herein, we have designed and developed a ‘pie' structured electrode, which provides an excellent balance between gravimetric and areal energy densities. Combining lotus root-like multichannel carbon nanofibers ‘filling' and amino-functionalized graphene ‘crust', the free-standing paper electrode (S mass loading: 3.6 mg cm−2) delivers high specific capacity of 1,314 mAh g−1 (4.7 mAh cm−2) at 0.1 C (0.6 mA cm−2) accompanied with good cycling stability. Moreover, the areal capacity can be further boosted to more than 8 mAh cm−2 by stacking three layers of paper electrodes with S mass loading of 10.8 mg cm−2. PMID:26608228

Improved transfer of graphene for gated Schottky-junction, vertical, organic, field-effect transistors.

PubMed

Lemaitre, Maxime G; Donoghue, Evan P; McCarthy, Mitchell A; Liu, Bo; Tongay, Sefaattin; Gila, Brent; Kumar, Purushottam; Singh, Rajiv K; Appleton, Bill R; Rinzler, Andrew G

2012-10-23

An improved process for graphene transfer was used to demonstrate high performance graphene enabled vertical organic field effect transistors (G-VFETs). The process reduces disorder and eliminates the polymeric residue that typically plagues transferred films. The method also allows for purposely creating pores in the graphene of a controlled areal density. Transconductance observed in G-VFETs fabricated with a continuous (pore-free) graphene source electrode is attributed to modulation of the contact barrier height between the graphene and organic semiconductor due to a gate field induced Fermi level shift in the low density of electronic-states graphene electrode. Pores introduced in the graphene source electrode are shown to boost the G-VFET performance, which scales with the areal pore density taking advantage of both barrier height lowering and tunnel barrier thinning. Devices with areal pore densities of 20% exhibit on/off ratios and output current densities exceeding 10(6) and 200 mA/cm(2), respectively, at drain voltages below 5 V.

A VLA (Very Large Array) Search for 5 GHz Radio Transients and Variables at Low Galactic Latitudes

NASA Technical Reports Server (NTRS)

Ofek, E. O.; Frail, D. A.; Breslauer, B.; Kulkarni, S. R.; Chandra, P.; Gal-Yam, A.; Kasliwal, M. M.; Gehrels, N.

2012-01-01

We present the results of a 5GHz survey with the Very Large Array (VLA) and the expanded VLA, designed to search for short-lived (approx < 1 day) transients and to characterize the variability of radio sources at milli-Jansky levels. A total sky area of 2.66 sq. deg, spread over 141 fields at low Galactic latitudes (b approx equals 6 - 8 deg) was observed 16 times with a cadence that was chosen to sample timescales of days, months and years. Most of the data were reduced, analyzed and searched for transients in near real time. Interesting candidates were followed up using visible light telescopes (typical delays of 1 - 2 hr) and the X-Ray Telescope on board the Swift satellite. The final processing of the data revealed a single possible transient with a flux density of f(sub v) approx equals 2.4mJy. This implies a transients sky surface density of kappa(f(sub v) > 1.8mJy) = 0.039(exp +0.13,+0.18) (sub .0.032,.0.038) / sq. deg (1, 2 sigma confidence errors). This areal density is consistent with the sky surface density of transients from the Bower et al. survey extrapolated to 1.8mJy. Our observed transient areal density is consistent with a Neutron Stars (NSs) origin for these events. Furthermore, we use the data to measure the sources variability on days to years time scales, and we present the variability structure function of 5GHz sources. The mean structure function shows a fast increase on approximately 1 day time scale, followed by a slower increase on time scales of up to 10 days. On time scales between 10 - 60 days the structure function is roughly constant. We find that approx > 30% of the unresolved sources brighter than 1.8mJy are variable at the > 4-sigma confidence level, presumably due mainly to refractive scintillation.

Evasion of CO2 from streams - the dominant component of the carbon export through the aquatic conduit in a boreal landscape.

PubMed

Wallin, Marcus B; Grabs, Thomas; Buffam, Ishi; Laudon, Hjalmar; Agren, Ånneli; Öquist, Mats G; Bishop, Kevin

2013-03-01

Evasion of gaseous carbon (C) from streams is often poorly quantified in landscape C budgets. Even though the potential importance of the capillary network of streams as C conduits across the land-water-atmosphere interfaces is sometimes mentioned, low-order streams are often left out of budget estimates due to being poorly characterized in terms of gas exchange and even areal surface coverage. We show that evasion of C is greater than all the total dissolved C (both organic and inorganic) exported downstream in the waters of a boreal landscape. In this study evasion of carbon dioxide (CO2 ) from running waters within a 67 km(2) boreal catchment was studied. During a 4 year period (2006-2009) 13 streams were sampled on 104 different occasions for dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). From a locally determined model of gas exchange properties, we estimated the daily CO2 evasion with a high-resolution (5 × 5 m) grid-based stream evasion model comprising the entire ~100 km stream network. Despite the low areal coverage of stream surface, the evasion of CO2 from the stream network constituted 53% (5.0 (±1.8) g C m(-2)  yr(-1) ) of the entire stream C flux (9.6 (±2.4) g C m(-2)  yr(-1) ) (lateral as DIC, DOC, and vertical as CO2 ). In addition, 72% of the total CO2 loss took place already in the first- and second-order streams. This study demonstrates the importance of including CO2 evasion from low-order boreal streams into landscape C budgets as it more than doubled the magnitude of the aquatic conduit for C from this landscape. Neglecting this term will consequently result in an overestimation of the terrestrial C sink strength in the boreal landscape. © 2012 Blackwell Publishing Ltd.

Estimating changes in urban land and urban population using refined areal interpolation techniques

NASA Astrophysics Data System (ADS)

Zoraghein, Hamidreza; Leyk, Stefan

2018-05-01

The analysis of changes in urban land and population is important because the majority of future population growth will take place in urban areas. U.S. Census historically classifies urban land using population density and various land-use criteria. This study analyzes the reliability of census-defined urban lands for delineating the spatial distribution of urban population and estimating its changes over time. To overcome the problem of incompatible enumeration units between censuses, regular areal interpolation methods including Areal Weighting (AW) and Target Density Weighting (TDW), with and without spatial refinement, are implemented. The goal in this study is to estimate urban population in Massachusetts in 1990 and 2000 (source zones), within tract boundaries of the 2010 census (target zones), respectively, to create a consistent time series of comparable urban population estimates from 1990 to 2010. Spatial refinement is done using ancillary variables such as census-defined urban areas, the National Land Cover Database (NLCD) and the Global Human Settlement Layer (GHSL) as well as different combinations of them. The study results suggest that census-defined urban areas alone are not necessarily the most meaningful delineation of urban land. Instead, it appears that alternative combinations of the above-mentioned ancillary variables can better depict the spatial distribution of urban land, and thus make it possible to reduce the estimation error in transferring the urban population from source zones to target zones when running spatially-refined temporal areal interpolation.

Changing Urbania: Estimating Changes in Urban Land and Urban Population Using Refined Areal Interpolation Techniques

NASA Astrophysics Data System (ADS)

Zoraghein, H.; Leyk, S.; Balk, D.

2017-12-01

The analysis of changes in urban land and population is important because the majority of future population growth will take place in urban areas. The U.S. Census historically classifies urban land using population density and various land-use criteria. This study analyzes the reliability of census-defined urban lands for delineating the spatial distribution of urban population and estimating its changes over time. To overcome the problem of incompatible enumeration units between censuses, regular areal interpolation methods including Areal Weighting (AW) and Target Density Weighting (TDW), with and without spatial refinement, are implemented. The goal in this study is to estimate urban population in Massachusetts in 1990 and 2000 (source zones), within tract boundaries of the 2010 census (target zones), respectively, to create a consistent time series of comparable urban population estimates from 1990 to 2010. Spatial refinement is done using ancillary variables such as census-defined urban areas, the National Land Cover Database (NLCD) and the Global Human Settlement Layer (GHSL) as well as different combinations of them. The study results suggest that census-defined urban areas alone are not necessarily the most meaningful delineation of urban land. Instead it appears that alternative combinations of the above-mentioned ancillary variables can better depict the spatial distribution of urban land, and thus make it possible to reduce the estimation error in transferring the urban population from source zones to target zones when running spatially-refined temporal areal interpolation.

Effect of electrode sub-micron surface feature size on current generation of Shewanella oneidensis in microbial fuel cells

NASA Astrophysics Data System (ADS)

Ye, Zhou; Ellis, Michael W.; Nain, Amrinder S.; Behkam, Bahareh

2017-04-01

Microbial fuel cells (MFCs) are envisioned to serve as compact and sustainable sources of energy; however, low current and power density have hindered their widespread use. Introduction of 3D micro/nanostructures on the MFC anode is known to improve its performance by increasing the surface area available for bacteria attachment; however, the role of the feature size remains poorly understood. To delineate the role of feature size from the ensuing surface area increase, nanostructures with feature heights of 115 nm and 300 nm, both at a height to width aspect ratio of 0.3, are fabricated in a grid pattern on glassy carbon electrodes (GCEs). Areal current densities and bacteria attachment densities of the patterned and unpatterned GCEs are compared using Shewanella oneidensis Δbfe in a three-electrode bioreactor. The 115 nm features elicit a remarkable 40% increase in current density and a 78% increase in bacterial attachment density, whereas the GCE with 300 nm pattern does not exhibit significant change in current density or bacterial attachment density. The current density dependency on feature size is maintained over the entire 160 h experiment. Thus, optimally sized surface features have a substantial effect on current production that is independent of their effect on surface area.

Femtosecond laser full and partial texturing of steel surfaces to reduce friction in lubricated contact

NASA Astrophysics Data System (ADS)

Ancona, Antonio; Carbone, Giuseppe; De Filippis, Michele; Volpe, Annalisa; Lugarà, Pietro Mario

2014-12-01

Minimizing mechanical losses and friction in vehicle engines would have a great impact on reducing fuel consumption and exhaust emissions, to the benefit of environmental protection. With this scope, laser surface texturing (LST) with femtosecond pulses is an emerging technology, which consists of creating, by laser ablation, an array of high-density microdimples on the surface of a mechanical device. The microtexture decreases the effective contact area and, in case of lubricated contact, acts as oil reservoir and trap for wear debris, leading to an overall friction reduction. Depending on the lubrication regime and on the texture geometry, several mechanisms may concur to modify friction such as the local reduction of the shear stress, the generation of a hydrodynamic lift between the surfaces or the formation of eddy-like flows at the bottom of the dimple cavities. All these effects have been investigated by fabricating and characterizing several LST surfaces by femtosecond laser ablation with different features: partial/full texture, circular/elliptical dimples, variable diameters, and depths but equivalent areal density. More than 85% of friction reduction has been obtained from the circular dimple geometry, but the elliptical texture allows adjusting the friction coefficient by changing its orientation with respect to the sliding direction.

Study of adhesion and friction properties on a nanoparticle gradient surface: transition from JKR to DMT contact mechanics.

PubMed

Ramakrishna, Shivaprakash N; Nalam, Prathima C; Clasohm, Lucy Y; Spencer, Nicholas D

2013-01-08

We have previously investigated the dependence of adhesion on nanometer-scale surface roughness by employing a roughness gradient. In this study, we correlate the obtained adhesion forces on nanometer-scale rough surfaces to their frictional properties. A roughness gradient with varying silica particle (diameter ≈ 12 nm) density was prepared, and adhesion and frictional forces were measured across the gradient surface in perfluorodecalin by means of atomic force microscopy with a polyethylene colloidal probe. Similarly to the pull-off measurements, the frictional forces initially showed a reduction with decreasing particle density and later an abrupt increase as the colloidal sphere began to touch the flat substrate beneath, at very low particle densities. The friction-load relation is found to depend on the real contact area (A(real)) between the colloid probe and the underlying particles. At high particle density, the colloidal sphere undergoes large deformations over several nanoparticles, and the contact adhesion (JKR type) dominates the frictional response. However, at low particle density (before the colloidal probe is in contact with the underlying surface), the colloidal sphere is suspended by a few particles only, resulting in local deformations of the colloid sphere, with the frictional response to the applied load being dominated by long-range, noncontact (DMT-type) interactions with the substrate beneath.

Remotely sensing the German Wadden Sea-a new approach to address national and international environmental legislation.

PubMed

Müller, Gabriele; Stelzer, Kerstin; Smollich, Susan; Gade, Martin; Adolph, Winny; Melchionna, Sabrina; Kemme, Linnea; Geißler, Jasmin; Millat, Gerald; Reimers, Hans-Christian; Kohlus, Jörn; Eskildsen, Kai

2016-10-01

The Wadden Sea along the North Sea coasts of Denmark, Germany, and the Netherlands is the largest unbroken system of intertidal sand and mud flats in the world. Its habitats are highly productive and harbour high standing stocks and densities of benthic species, well adapted to the demanding environmental conditions. Therefore, the Wadden Sea is one of the most important areas for migratory birds in the world and thus protected by national and international legislation, which amongst others requires extensive monitoring. Due to the inaccessibility of major areas of the Wadden Sea, a classification approach based on optical and radar remote sensing has been developed to support environmental monitoring programmes. In this study, the general classification framework as well as two specific monitoring cases, mussel beds and seagrass meadows, are presented. The classification of mussel beds profits highly from inclusion of radar data due to their rough surface and achieves agreements of up to 79 % with areal data from the regular monitoring programme. Classification of seagrass meadows reaches even higher agreements with monitoring data (up to 100 %) and furthermore captures seagrass densities as low as 10 %. The main classification results are information on area and location of individual habitats. These are needed to fulfil environmental legislation requirements. One of the major advantages of this approach is the large areal coverage with individual satellite images, allowing simultaneous assessment of both accessible and inaccessible areas and thus providing a more complete overall picture.

In situ growth of NiCo2S4 nanotube arrays on Ni foam for supercapacitors: Maximizing utilization efficiency at high mass loading to achieve ultrahigh areal pseudocapacitance

NASA Astrophysics Data System (ADS)

Chen, Haichao; Jiang, Jianjun; Zhang, Li; Xia, Dandan; Zhao, Yuandong; Guo, Danqing; Qi, Tong; Wan, Houzhao

2014-05-01

Self-standing NiCo2S4 nanotube arrays have been in situ grown on Ni foam by the anion-exchange reaction and directly used as the electrode for supercapacitors. The NiCo2S4 nanotube in the arrays effectively reduces the inactive material and increases the electroactive surface area because of the ultrathin wall, which is quite competent to achieve high utilization efficiency at high electroactive materials mass loading. The NiCo2S4 nanotube arrays hybrid electrode exhibits an ultrahigh specific capacitance of 14.39 F cm-2 at 5 mA cm-2 with excellent rate performance (67.7% retention for current increases 30 times) and cycling stability (92% retention after 5000 cycles) at a high mass loading of 6 mg cm-2. High areal capacitance (4.68 F cm-2 at 10 mA cm-2), high energy density (31.5 Wh kg-1 at 156.6 W kg-1) and high power density (2348.5 W kg-1 at 16.6 Wh kg-1) can be achieved by assembling asymmetric supercapacitor with reduced graphene oxide at a total active material mass loading as high as 49.5 mg. This work demonstrates that NiCo2S4 nanotube arrays structure is a superior electroactive material for high-performance supercapacitors even at a mass loading of potential application-specific scale.

The Role of Phytoplankton Dynamics in the Seasonal and Interannual Variability of Carbon in the Subpolar North Atlantic - a Modeling Study

NASA Technical Reports Server (NTRS)

Signorini, Sergio; Hakkinen, Sirpa; Gudmundsson, K.; Olsen, A.; Omar, A. M.; Olafsson, J.; Reverdin, G.; Henson, S. A.; McClain, C. R.; Worthen, D. L.

2014-01-01

We developed an ecosystem/biogeochemical model system, which includes multiple phytoplankton functional groups and carbon cycle dynamics, and applied it to investigate physical-biological interactions in Icelandic waters. Satellite and in situ data were used to evaluate the model. Surface seasonal cycle amplitudes and biases of key parameters (DIC, TA, pCO2, air-sea CO2 flux, and nutrients) are significantly improved when compared to surface observations by prescribing deep water values and trends, based on available data. The seasonality of the coccolithophore and "other phytoplankton" (diatoms and dinoflagellates) blooms is in general agreement with satellite ocean color products. Nutrient supply, biomass and calcite concentrations are modulated by light and mixed layer depth seasonal cycles. Diatoms are the most abundant phytoplankton, with a large bloom in early spring and a secondary bloom in fall. The diatom bloom is followed by blooms of dinoflagellates and coccolithophores. The effect of biological changes on the seasonal variability of the surface ocean pCO2 is nearly twice the temperature effect, in agreement with previous studies. The inclusion of multiple phytoplankton functional groups in the model played a major role in the accurate representation of CO2 uptake by biology. For instance, at the peak of the bloom, the exclusion of coccolithophores causes an increase in alkalinity of up to 4 µmol kg(sup -1) with a corresponding increase in DIC of up to 16 µmol kg(sup -1). During the peak of the bloom in summer, the net effect of the absence of the coccolithophores bloom is an increase in pCO2 of more than 20 µatm and a reduction of atmospheric CO2 uptake of more than 6 mmolm(sup -2) d(sup -1). On average, the impact of coccolithophores is an increase of air-sea CO2 flux of about 27 %. Considering the areal extent of the bloom from satellite images within the Irminger and Icelandic Basins, this reduction translates into an annual mean of nearly 1500 tonnes C yr(sup -1).

Hydrogeology and simulation of ground-water flow at the Gettysburg Elevator Plant Superfund Site, Adams County, Pennsylvania

USGS Publications Warehouse

Low, Dennis J.; Goode, Daniel J.; Risser, Dennis W.

2000-01-01

Ground water in Triassic-age sedimentary fractured-rock aquifers in the area of Gettysburg, Pa., is used as drinking water and for industrial and commercial supply. In 1983, ground water at the Gettysburg Elevator Plant was found by the Pennsylvania Department of Environmental Resources to be contaminated with trichloroethene, 1,1,1-trichloroethane, and other synthetic organic compounds. As part of the U.S. Environmental Protection Agency?s Comprehensive Environmental Response, Compensation, and Liability Act, 1980 process, a Remedial Investigation was completed in July 1991, a method of site remediation was issued in the Record of Decision dated June 1992, and a Final Design Report was completed in May 1997. In cooperation with the U.S. Environmental Protection Agency in the hydrogeologic assessment of the site remediation, the U.S. Geological Survey began a study in 1997 to determine the effects of the onsite and offsite extraction wells on ground-water flow and contaminant migration from the Gettysburg Elevator Plant. This determination is based on hydrologic and geophysical data collected from 1991 to 1998 and on results of numerical model simulations of the local ground-water flow-system. The Gettysburg Elevator Site is underlain by red, green, gray, and black shales of the Heidlersburg Member of the Gettysburg Formation. Correlation of natural-gamma logs indicates the sedimentary rock strike about N. 23 degrees E. and dip about 23 degrees NW. Depth to bedrock onsite commonly is about 6 feet but offsite may be as deep as 40 feet. The ground-water system consists of two zones?a thin, shallow zone composed of soil, clay, and highly weathered bedrock and a thicker, nonweathered or fractured bedrock zone. The shallow zone overlies the bedrock zone and truncates the dipping beds parallel to land surface. Diabase dikes are barriers to ground-water flow in the bedrock zone. The ground-water system is generally confined or semi-confined, even at shallow depths. Depth to water can range from flowing at land surface to more than 71 feet below land surface. Potentiometric maps based on measured water levels at the Gettysburg Elevator Plant indicate ground water flows from west to east, towards Rock Creek. Multiple-well aquifer tests indicate the system is heterogeneous and flow is primarily in dipping beds that contain discrete secondary openings separated by less permeable beds. Water levels in wells open to the pumped bed, as projected along the dipping stratigraphy, are drawn down more than water levels in wells not open to the pumped bed. Ground-water flow was simulated for steady-state conditions prior to pumping and long-term average pumping conditions. The three-dimensional numerical flow model (MODFLOW) was calibrated by use of a parameter estimation program (MODFLOWP). Steady-state conditions were assumed for the calibration period of 1996. An effective areal recharge rate of 7 inches was used in model calibration. The calibrated flow model was used to evaluate the effectiveness of the current onsite and offsite extraction well system. The simulation results generally indicate that the extraction system effectively captures much of the ground-water recharge at the Gettysburg Elevator Plant and, hence, contaminated ground-water migrating from the site. Some of the extraction wells pump at low rates and have very small contributing areas. Results indicate some areal recharge onsite will move to offsite extraction wells.

Satellite-derived estimates of forest leaf area index in southwest Western Australia are not tightly coupled to interannual variations in rainfall: implications for groundwater decline in a drying climate.

PubMed

Smettem, Keith R J; Waring, Richard H; Callow, John N; Wilson, Melissa; Mu, Qiaozhen

2013-08-01

There is increasing concern that widespread forest decline could occur in regions of the world where droughts are predicted to increase in frequency and severity as a result of climate change. The average annual leaf area index (LAI) is an indicator of canopy cover and the difference between the annual maximum and minimum LAI is an indicator of annual leaf turnover. In this study, we analyzed satellite-derived estimates of monthly LAI across forested coastal catchments of southwest Western Australia over a 12 year period (2000-2011) that included the driest year on record for the last 60 years. We observed that over the 12 year study period, the spatial pattern of average annual satellite-derived LAI values was linearly related to mean annual rainfall. However, interannual changes to LAI in response to changes in annual rainfall were far less than expected from the long-term LAI-rainfall trend. This buffered response was investigated using a physiological growth model and attributed to availability of deep soil moisture and/or groundwater storage. The maintenance of high LAIs may be linked to a long-term decline in areal average underground water storage and diminished summer flows, with an emerging trend toward more ephemeral flow regimes. © 2013 John Wiley & Sons Ltd.

An ecological analysis of pertussis disease in Minnesota, 2009-2013.

PubMed

Iroh Tam, P Y; Menk, J S; Hughes, J; Kulasingam, S L

2016-03-01

The increase in pertussis cases in Minnesota in the last decade has been mainly attributed to the switch from whole cell to acellular pertussis [as part of the diphtheria, tetanus and acellular pertussis vaccine (DTaP)]. It is unclear, however, to what degree community-level risk factors also contribute. Understanding these factors can help inform public health policy-makers about where else to target resources. We performed an ecological analysis within Minnesota to identify risk factors at the county level using a Bayesian Poisson generalized linear areal model to account for spatial dependence. Univariate analyses suggested an association between increased pertussis rates at the county level and white maternal ethnicity, being US born, urban counties and average household size. In the multivariable analysis, the rate of pertussis was 1·79 times greater for urban vs. rural counties and 4·75 times greater for counties with a one-person larger average household size. Pertussis rates in counties with higher (i.e. 4+DTaP) receipt in children were 0·97 times lower. Examining county-level factors associated with varying levels of pertussis may help identify those counties that would most benefit from targeted interventions and increased resource allocation.

Conceptual design of the gamma-to-electron magnetic spectrometer for the National Ignition Facility

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

Kim, Y., E-mail: yhkim@lanl.gov; Herrmann, H. W.; Jorgenson, H. J.

2014-11-15

The Gamma-to-Electron Magnetic Spectrometer (GEMS) diagnostic is designed to measure the prompt γ-ray energy spectrum during high yield deuterium-tritium (DT) implosions at the National Ignition Facility (NIF). The prompt γ-ray spectrum will provide “burn-averaged” observables, including total DT fusion yield, total areal density (ρR), ablator ρR, and fuel ρR. These burn-averaged observables are unique because they are essentially averaged over 4π, providing a global reference for the line-of-sight-specific measurements typical of x-ray and neutron diagnostics. The GEMS conceptual design meets the physics-based requirements: ΔE/E = 3%–5% can be achieved in the range of 2–25 MeV γ-ray energy. Minimum DT neutronmore » yields required for 15% measurement uncertainty at low-resolution mode are: 5 × 10{sup 14} DT-n for ablator ρR (at 0.2 g/cm{sup 2}); 2 × 10{sup 15} DT-n for total DT yield (at 4.2 × 10{sup −5} γ/n); and 1 × 10{sup 16} DT-n for fuel ρR (at 1 g/cm{sup 2})« less

Estimated areal extent of colonies of black-tailed prairie dogs in the northern Great Plains

USGS Publications Warehouse

Sidle, John G.; Johnson, Douglas H.; Euliss, Betty R.

2001-01-01

During 1997–1998, we undertook an aerial survey, with an aerial line-intercept technique, to estimate the extent of colonies of black-tailed prairie dogs (Cynomys ludovicianus) in the northern Great Plains states of Nebraska, North Dakota, South Dakota, and Wyoming. We stratified the survey based on knowledge of colony locations, computed 2 types of estimates for each stratum, and combined ratio estimates for high-density strata with average density estimates for low-density strata. Estimates of colony areas for black-tailed prairie dogs were derived from the average percentages of lines intercepting prairie dog colonies and ratio estimators. We selected the best estimator based on the correlation between length of transect line and length of intercepted colonies. Active colonies of black-tailed prairie dogs occupied 2,377.8 km2 ± 186.4 SE, whereas inactive colonies occupied 560.4 ± 89.2 km2. These data represent the 1st quantitative assessment of black-tailed prairie dog colonies in the northern Great Plains. The survey dispels popular notions that millions of hectares of colonies of black-tailed prairie dogs exist in the northern Great Plains and can form the basis for future survey efforts.

Conceptual design of the gamma-to-electron magnetic spectrometer for the National Ignition Facility

DOE PAGES

Kim, Y.; Herrmann, H. W.; Jorgenson, H. J.; ...

2014-08-01

The Gamma-to-Electron Magnetic Spectrometer (GEMS) diagnostic is designed to measure the prompt γ-ray energy spectrum during high yield deuterium-tritium (DT) implosions at the National Ignition Facility (NIF). The prompt γ-ray spectrum will provide ‘burn-averaged’ observables, including total DT fusion yield, total areal density (ρR), ablator ρR, and fuel ρR. These burn-averaged observables are unique because they are essentially averaged over 4π, providing a global reference for the line-of-sight-specific measurements typical of x-ray and neutron diagnostics. The GEMS conceptual design meets the physics-based requirements: ΔE/E = 3 - 5% can be achieved in the range of 2 - 25 MeV γ-raymore » energy. Minimum DT neutron yields required for 15% measurement uncertainty at low-resolution mode are: 5×10 14 DT-n for ablator ρR (at 0.2 g/cm 2); 2×10 15 DT-n for total DT yield (at 4.2×10 -5γ /n); and 1×10 16 DT-n for fuel ρR (at 1 g/cm 2).« less

A reconstruction of sea surface temperature variability in the southeastern Gulf of Mexico from 1734 to 2008 C.E. using cross-dated Sr/Ca records from the coral Siderastrea siderea

NASA Astrophysics Data System (ADS)

DeLong, Kristine L.; Flannery, Jennifer A.; Poore, Richard Z.; Quinn, Terrence M.; Maupin, Christopher R.; Lin, Ke; Shen, Chuan-Chou

2014-05-01

This study uses skeletal variations in coral Sr/Ca from three Siderastrea siderea coral colonies within the Dry Tortugas National Park in the southeastern Gulf of Mexico (24°42'N, 82°48'W) to reconstruct monthly sea surface temperature (SST) variations from 1734 to 2008 Common Era (C.E.). Calibration and verification of the replicated coral Sr/Ca-SST reconstruction with local, regional, and historical temperature records reveals that this proxy-temperature relationship is stable back to 1879 C.E. The coral SST reconstruction contains robust interannual ( 2.0°C) and multidecadal variability ( 1.5°C) for the past 274 years, the latter of which does not covary with the Atlantic Multidecadal Oscillation. Winter SST extremes are more variable than summer SST extremes (±2.2°C versus ±1.6°C, 2σ) suggesting that Loop Current transport in the winter dominates variability on interannual and longer time scales. Summer SST maxima are increasing (+1.0°C for 274 years, σMC = ±0.5°C, 2σ), whereas winter SST minima contain no significant trend. Colder decades ( 1.5°C) during the Little Ice Age (LIA) do not coincide with decades of sunspot minima. The coral SST reconstruction contains similar variability to temperature reconstructions from the northern Gulf of Mexico (planktic foraminifer Mg/Ca) and the Caribbean Sea (coral Sr/Ca) suggesting areal reductions in the Western Hemisphere Warm Pool during the LIA. Mean summer coral SST extremes post-1985 C.E. (29.9°C) exceeds the long-term summer average (29.2°C for 1734-2008 C.E.), yet the warming trend after 1985 C.E. (0.04°C for 24 years, σMC = ±0.5, 2σ) is not significant, whereas Caribbean coral Sr/Ca studies contain a warming trend for this interval.

In Situ Multilength-Scale Tracking of Dimensional and Viscoelastic Changes in Composite Battery Electrodes.

PubMed

Dargel, Vadim; Jäckel, Nicolas; Shpigel, Netanel; Sigalov, Sergey; Levi, Mikhael D; Daikhin, Leonid; Presser, Volker; Aurbach, Doron

2017-08-23

Intercalation-induced dimensional changes in a composite battery electrode (comprising a polymeric binder) are one of the major factors limiting electrode cycling performance. Since electrode performance is expressed by the quantities averaged over its entire surface area (e.g., capacity retention, Faradaic efficiency, rate capability), significant efforts have been made to develop a methodology allowing its facile mechanical diagnostics at the same areal scale. Herein we introduce such a generic methodology for a highly sensitive in situ monitoring of intrinsic mechanical properties of composite battery electrodes. The gravimetric, dimensional, viscoelastic, and adhesive changes in the composite electrodes caused by Li-ions intercalation are assessed noninvasively and in real time by electrochemical quartz-crystal microbalance with dissipation monitoring (EQCM-D). Multiharmonic acoustic waves generated by EQCM-D penetrate into thin porous electrodes comprising either rigid or a soft binder resulting in frequency and dissipation changes quantified by analytical acoustic load impedance models. As a first demonstration, we used a composite LiFePO 4 (LFP) electrode containing either polyvinylidene dichloride (PVdF) or Na carboximethyl cellulose (NaCMC) as rigid and viscoelastic binders, respectively, in aqueous electrolytes. The intercalation-induced volume changes of LFP electrode were evaluated from a hydrodynamic correction to the mass effect of the intercalated ions for PVdF, and both components of the effective complex shear modulus (i.e., storage and loss moduli) in case of NaCMC binder have been extracted. The sliding friction coefficients for large particles bound at their bottom to the quartz crystal surface (a measure of the adhesion strength of binders) has also been evaluated. Tracking the mechanical properties of the composite electrodes in different environments and charging/cycling conditions in a self-consistent manner provides all necessary conditions for an optimal selection of the polymeric binders resistant to intercalation-induced volume changes of intercalation particles.

Effects of inhomogeneity at stagnation in 3D simulations of ICF implosions

NASA Astrophysics Data System (ADS)

Appelbe, Brian

2016-10-01

The stagnation phase of an ICF implosion is characterized by a hotspot and dense fuel layer that are spatially and temporally inhomogeneous. Perturbation growth during the implosion results in significant asymmetry at stagnation while the hotspot size, density and temperature change rapidly, even in non-igniting capsules. Diagnosing these inhomogeneities is necessary to increase yield in ICF experiments. In this work, 3D radiation hydrodynamic simulations of perturbed indirect drive ICF capsules are carried out using the CHIMERA code. During the stagnation phase a suite of novel and computationally efficient simulation tools are used to produce synthetic time-resolved neutron spectra and images. These tools allow a detailed study of the effects of hotspot inhomogeneities on diagnostic signals. Results show that the burn-averaged ion temperature drops rapidly during thermonuclear burn as the hotspot evolves from a localised, shock-heated region to a more massive, non-uniform plasma. Primary DD and DT neutron spectra show that there is significant residual bulk fluid motion at stagnation, complicating the measurement of ion temperature. Different perturbation modes cause different levels of anisotropic spectra shifts and broadening. However, in all cases the discrepancies between the DD and DT spectra are a reliable indicator of residual motion at stagnation. The simulations are used to examine the relationship between neutron scattering and areal density (ρR). Three measures of areal density are simulated: downscattered neutron ratio, attenuated primary neutron yield and nT backscatter edge. Each of these diagnoses the magnitude and anisotropy of the ρR with varying success, with accuracy decreasing for higher mode perturbations. Contributions to the neutron energy spectra from T +T reactions, secondary DT reactions and deuteron break-up are also evaluated.

Understory and small trees contribute importantly to stemflow of a lower montane cloud forest

NASA Astrophysics Data System (ADS)

González Martínez, T. M.; Wiliams-Linera, G.; Holwerda, F.

2016-12-01

Stemflow (Sf) measurements in rainforests and montane forests dominated by large trees rarely include the understory and small trees. In the present study, contributions of woody understory (> 1 m height and < 5 cm DBH), small trees (5 < DBH < 10 cm) and upper canopy trees (> 10 cm DBH) to overall Sf of a lower montane cloud forest in central Veracruz, Mexico, were quantified. Incident precipitation (P), Sf volume and vegetation structure were measured. Subsequently, stemflow funneling ratios (SFR) were calculated, and allometric relationships between tree basal area and Sf volume were used to scale up measurements from individual trees to the stand level. Additionally, two other common methods to calculate areal Sf were used for comparative purposes. Understory woody plants, small trees and upper canopy trees represented 96, 2 and 2 %, respectively, of the total density. Upper canopy trees had the lowest SFRs (1.6 ± 0.5 on average), while the lower understory (> 1 m and < 2 m height) had the highest (36.1 ± 6.4). Small trees and upper understory (> 2 m) presented similar SFRs (22.9 ± 5.4 and 20.2 ± 3.9, respectively). Different scaling methods yielded very similar results for all but the upper understory. Overall areal Sf during the study period was 19 mm (3.8 % of rainfall), to which the understory contributed 66.3 % (12.6 mm), small trees 12.6 % (2.4 mm) and upper canopy trees 21.1 % (4.0 mm). Our results suggest that woody understory vegetation and small trees can have an important role in Sf generation of tall humid tropical forests, provided that the density of plants in these groups is high enough.

An overview of beam diagnostic and control systems for 50 MeV AREAL Linac

NASA Astrophysics Data System (ADS)

Sargsyan, A. A.; Amatuni, G. A.; Sahakyan, V. V.; Zanyan, G. S.; Martirosyan, N. W.; Vardanyan, V. V.; Grigoryan, B. A.

2017-03-01

Advanced Research Electron Accelerator Laboratory (AREAL) is an electron linear accelerator project with a laser driven RF gun being constructed at CANDLE Synchrotron Research Institute. After the successful operation of the gun section at 5 MeV, a program of facility energy enhancement up to 50 MeV is launched. In this paper the current status of existing diagnostic and control systems, as well as the results of electron beam parameter measurements are presented. The approaches of intended diagnostic and control systems for the upgrade program are also described.

Electrical and Structural Characterization of Web Dendrite Crystals

NASA Technical Reports Server (NTRS)

Schwuttke, G. H.; Koliwad, K.; Dumas, K. A.

1985-01-01

Minority carrier lifetime distributions in silicon web dendrites are measured. Emphasis is placed on measuring areal homogeneity of lifetime, show its dependency on structural defects, and its unique change during hot processing. The internal gettering action of defect layers present in web crystals and their relation to minority carrier lifetime distributions is discussed. Minority carrier lifetime maps of web dendrites obtained before and after high temperature heat treatment are compared to similar maps obtained from 100 mm diameter Czochralski silicon wafers. Such maps indicate similar or superior areal homogeneity of minority carrier lifetime in webs.

Natural resources inventory and land evaluation in Switzerland

NASA Technical Reports Server (NTRS)

Haefner, H. (Principal Investigator)

1976-01-01

The author has identified the following significant results. Using MSS channels 5 and 7 and a supervised classification system with a PPD classification algorithm, it was possible to map the exact areal extent of the snow cover and of the transition zone with melting snow patches and snow free parts of various sizes over a large area under different aspects such as relief, exposure, shadows etc. A correlation of the data from ground control, areal underflights and earth resources satellites provided a very accurate interpretation of the melting procedure of snow in high mountains.

Surface Monitoring of CFRP Structures for Adhesive Bonding

NASA Technical Reports Server (NTRS)

Ledesma, Rodolfo; Palmieri, Frank L.; Yost, William T.; Connell, John W.; Fitz-Gerald, James M.

2017-01-01

Adhesive bonding of composite materials requires reliable monitoring and detection of surface contaminants to assure robust and durable bonded structures. Surface treatment and effective monitoring prior to bonding is essential in order to obtain a surface free from contaminants that may degrade structural performance. Two techniques which monitor the effectiveness of the laser surface treatment of carbon fiber reinforced polymer (CFRP) materials are being investigated: laser induced breakdown spectroscopy (LIBS) and optically stimulated electron emission (OSEE). The applicability of LIBS to detect silicone contaminants on CFRP composites is studied using 35 ns Nd:YAG laser pulses at 355 nm with a pulse energy of 45 mJ. The LIBS regime in which pulse energies are < 100 mJ is referred to as mLIBS. CFRP surfaces were contaminated with polydimethylsiloxane (PDMS), a major component of silicone based mold release agents. The presence of PDMS is found by inspecting the Si I emission line at 288.2 nm. Untreated CFRP samples and CFRP contaminated with PDMS were tested. The PDMS areal density ranged from 0.36 Â+/- 0.04 to 0.51 Â+/- 0.16 mg/cm2. The results demonstrate the successful detection of PDMS on CFRP using mLIBS. In addition, OSEE was used to measure CFRP surface cleanliness pre- and post-treatment by laser ablation on specimens contaminated with PDMS coatings from 8 nm to 1311 nm in thickness. The results showed a significant increase in the OSEE photocurrent after laser surface treatment.

Buried topography of Utopia, Mars - Persistence of a giant impact depression

NASA Technical Reports Server (NTRS)

Mcgill, George E.

1989-01-01

Knobs, partially buried craters, ring fractures, and some mesas permit a qualitative determination of the topography buried beneath younger northern plains materials. These features are widely distributed in the Utopia area but are absent in a large, roughly circular region centered at about 48 deg N, 240 deg W. This implies the existence of a circular depression about 3300 km in diameter buried beneath Utopia Planitia that is interpreted to represent the central part of a very large impact basin. The presence of buried curved massifs around part of this depression, and a roughly coincident mascon, lend further support. Present topography, areal geology, and paleotopography of buried surfaces all point to the persistence of this major depression for almost the entire history of Mars.

Highly stretchable, transparent ionic touch panel

NASA Astrophysics Data System (ADS)

Kim, Chong-Chan; Lee, Hyun-Hee; Oh, Kyu Hwan; Sun, Jeong-Yun

2016-08-01

Because human-computer interactions are increasingly important, touch panels may require stretchability and biocompatibility in order to allow integration with the human body. However, most touch panels have been developed based on stiff and brittle electrodes. We demonstrate an ionic touch panel based on a polyacrylamide hydrogel containing lithium chloride salts. The panel is soft and stretchable, so it can sustain a large deformation. The panel can freely transmit light information because the hydrogel is transparent, with 98% transmittance for visible light. A surface-capacitive touch system was adopted to sense a touched position. The panel can be operated under more than 1000% areal strain without sacrificing its functionalities. Epidermal touch panel use on skin was demonstrated by writing words, playing a piano, and playing games.

Toward Large-Area Sub-Arcsecond X-Ray Telescopes

NASA Technical Reports Server (NTRS)

ODell, Stephen L.; Aldcroft, Thomas L.; Allured, Ryan; Atkins, Carolyn; Burrows, David N.; Cao, Jian; Chalifoux, Brandon D.; Chan, Kai-Wing; Cotroneo, Vincenzo; Elsner, Ronald F.;

Cortical Cartography and Caret Software

PubMed Central

Van Essen, David C.

2011-01-01

Caret software is widely used for analyzing and visualizing many types of fMRI data, often in conjunction with experimental data from other modalities. This article places Caret’s development in a historical context that spans three decades of brain mapping – from the early days of manually generated flat maps to the nascent field of human connectomics. It also highlights some of Caret’s distinctive capabilities. This includes the ease of visualizing data on surfaces and/or volumes and on atlases as well as individual subjects. Caret can display many types of experimental data using various combinations of overlays (e.g., fMRI activation maps, cortical parcellations, areal boundaries), and it has other features that facilitate the analysis and visualization of complex neuroimaging datasets. PMID:22062192

Positron radiography of ignition-relevant ICF capsules

NASA Astrophysics Data System (ADS)

Williams, G. J.; Chen, Hui; Field, J. E.; Landen, O. L.; Strozzi, D. J.

2017-12-01

Laser-generated positrons are evaluated as a probe source to radiograph in-flight ignition-relevant inertial confinement fusion capsules. Current ultraintense laser facilities are capable of producing 2 × 1012 relativistic positrons in a narrow energy bandwidth and short time duration. Monte Carlo simulations suggest that the unique characteristics of such positrons allow for the reconstruction of both capsule shell radius and areal density between 0.002 and 2 g/cm2. The energy-downshifted positron spectrum and angular scattering of the source particles are sufficient to constrain the conditions of the capsule between preshot and stagnation. We evaluate the effects of magnetic fields near the capsule surface using analytic estimates where it is shown that this diagnostic can tolerate line integrated field strengths of 100 T mm.