WorldWideScience

Sample records for surface-barrier edge effects

  1. Photoelectric effect in surface-barrier structures

    International Nuclear Information System (INIS)

    Kononenko, V.K.; Tupenevich, P.A.

    1985-08-01

    Deviations from the Fowler law were observed when investigating photoelectric emission in p-type ZnTe surface-barrier structures. The revealed peculiarities of the structure photosensitivity spectrum are explained by the electron transitions involving surface states at the metal-semiconductor interface. (author)

  2. Study of araldite in edge protection of n-type and p-type surface barrier detectors

    International Nuclear Information System (INIS)

    Alencar, M.A.V.; Jesus, E.F.O.; Lopes, R.T.

    1995-01-01

    The aim of this work is the realization of a comparative study between the surface barrier detectors performance n and type using the epoxy resin Araldite as edge protection material with the purpose of determining which type of detector (n or p) the use of Araldite is more indicated. The surface barrier detectors were constructed using n and p type silicon wafer with resistivity of 3350Ω.cm and 5850 Ω.cm respectively. In the n type detectors, the metals used as ohmic and rectifier contacts were the Al and Au respectively, while in the p type detectors, the ohmic and rectifier contacts were Au and Al. All metallic contacts were done by evaporation in high vacuum (∼10 -4 Torr) and with deposit of 40 μm/cm 2 . The obtained results for the detectors (reverse current of -350nA and resolution from 21 to 26 keV for p type detectors and reserve current of 1μA and resolution from 44 to 49 keV for n type detectors) tend to demonstrate that use of epoxy resin Araldite in the edge protection is more indicated to p type surface barrier detectors. (author). 3 refs., 4 figs., 1 tab

  3. Critical current density of BiSrCaCuO superconductors: effect of surface barriers

    International Nuclear Information System (INIS)

    Konczykowski, M.; Chikumoto, N.

    1992-01-01

    Effects of surface barriers on vortex motion in BiSrCaCuO-2212 high-temperature superconducting crystals is summarized. Characteristic features of this phenomenon appear in the hysteresis loop (shape of its ascending and descending branches), in the effect of 2.5 MeV electron irradiation, and in flux creep measurements (magnetization dependence to the crystal lateral dimension, size of the flux-creep barrier and the crossover as a function of temperature and time persistent current density). (A.B.). 25 refs., 3 figs

  4. Test Plan to Assess Fire Effects on the Function of an Engineered Surface Barrier

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Anderson L.; Berlin, Gregory T.; Cammann, Jerry W.; Leary, Kevin D.; Link, Steven O.

    2008-09-29

    Wildfire is a frequent perturbation in shrub steppe ecosystems, altering the flora, fauna, atmosphere, and soil of these systems. Research on the fire effects has focused mostly on natural ecosystems with essentially no attention on engineered systems like surface barriers. The scope of the project is to use a simulated wildfire to induce changes in an engineered surface barrier and document the effects on barrier performance. The main objective is to quantify the effects of burning and the resulting post-fire conditions on alterations in soil physical properties; hydrologic response, particularly the water balance; geochemical properties; and biological properties. A secondary objective is to use the lessons learned to maximize fire protection in the design of long-term monitoring systems based on electronic sensors. A simulated wildfire will be initiated, controlled and monitored at the 200-BP-1 barrier in collaboration with the Hanford Fire Department during the fall of 2008. The north half of the barrier will be divided into nine 12 x 12 m plots, each of which will be randomly assigned a fuel load of 2 kg m-2 or 4 kg m-2. Each plot will be ignited around the perimeter and flames allowed to carry to the centre. Any remaining unburned vegetation will be manually burned off using a drip torch. Progress of the fire and its effects will be monitored using point measurements of thermal, hydrologic, and biotic variables. Three measures of fire intensity will be used to characterize fire behavior: (1) flame height, (2) the maximum temperature at three vertical profile levels, and (3) total duration of elevated temperature at these levels. Pre-burn plant information, including species diversity, plant height, and canopy diameter will be measured on shrubs from the plots to be burned and from control plots at the McGee ranch. General assessments of shrub survival, recovery, and recruitment will be made after the fire. Near-surface soil samples will be collected pre- and

  5. Test Plan to Assess Fire Effects on the Function of an Engineered Surface Barrier

    International Nuclear Information System (INIS)

    Ward, Anderson L.; Berlin, Gregory T.; Cammann, Jerry W.; Leary, Kevin D.; Link, Steven O.

    2008-01-01

    Wildfire is a frequent perturbation in shrub steppe ecosystems, altering the flora, fauna, atmosphere, and soil of these systems. Research on the fire effects has focused mostly on natural ecosystems with essentially no attention on engineered systems like surface barriers. The scope of the project is to use a simulated wildfire to induce changes in an engineered surface barrier and document the effects on barrier performance. The main objective is to quantify the effects of burning and the resulting post-fire conditions on alterations in soil physical properties; hydrologic response, particularly the water balance; geochemical properties; and biological properties. A secondary objective is to use the lessons learned to maximize fire protection in the design of long-term monitoring systems based on electronic sensors. A simulated wildfire will be initiated, controlled and monitored at the 200-BP-1 barrier in collaboration with the Hanford Fire Department during the fall of 2008. The north half of the barrier will be divided into nine 12 x 12 m plots, each of which will be randomly assigned a fuel load of 2 kg m-2 or 4 kg m-2. Each plot will be ignited around the perimeter and flames allowed to carry to the centre. Any remaining unburned vegetation will be manually burned off using a drip torch. Progress of the fire and its effects will be monitored using point measurements of thermal, hydrologic, and biotic variables. Three measures of fire intensity will be used to characterize fire behavior: (1) flame height, (2) the maximum temperature at three vertical profile levels, and (3) total duration of elevated temperature at these levels. Pre-burn plant information, including species diversity, plant height, and canopy diameter will be measured on shrubs from the plots to be burned and from control plots at the McGee ranch. General assessments of shrub survival, recovery, and recruitment will be made after the fire. Near-surface soil samples will be collected pre- and

  6. Edge effects in composites

    International Nuclear Information System (INIS)

    Guz, A.N.; Kokhanenko, Yu.V.

    1995-01-01

    In the present article we survey papers on edge effects investigated by the rigorous approach. We interpret edge effects as stressed states created in a composite as a result of zones in which the stresses exhibit a rapidly changing behavior in comparison with the slow variation of the stresses outside such zones. Here the range of the edge effect is defined as the distance from the point of its inception to the boundary of the edge zone in a given direction. The transition of the stresses to the slowly varying state is determined within prescribed error limits. The size and configuration of the edge zone depends on the tolerated error. Clearly, the main difficulty associated with the rigorous approach is finding solutions of the elasticity problems. The finite-difference approach is suggested for the approximate solution of these problems. In light of the comparative time consumption of the finite-difference approach, it is best directed at certain classes of problems rather than at particular individual problems. Not too many papers on the investigation of edge effects by the rigorous approach have been published to date. Below, following in their footsteps, we formulate edge effect problems in composites, determine classes of problems, and investigate edge effects in composite materials and structural elements using them in Cartesian (planar and three-dimensional problems) and cylindrical (axisymmetric problems) coordinate frames. We note that the division of approaches to the study of edge effects into qualitative (nonrigorous) and quantitative (rigorous) reflects the authors own point of view. Of course, other schemes of classification of the approaches to the investigation of the regions of rapidly varying states in composites are possible

  7. Monitoring the Vadose Zone Moisture Regime Below a Surface Barrier

    Science.gov (United States)

    Zhang, Z. F.; Strickland, C. E.; Field, J. G.

    2009-12-01

    A 6000 m2 interim surface barrier has been constructed over a portion of the T Tank Farm in the Depart of Energy’s Hanford site. The purpose of using a surface barrier was to reduce or eliminate the infiltration of meteoric precipitation into the contaminated soil zone due to past leaks from Tank T-106 and hence to reduce the rate of movement of the plume. As part of the demonstration effort, vadose zone moisture is being monitored to assess the effectiveness of the barrier on the reduction of soil moisture flow. A vadose zone monitoring system was installed to measure soil water conditions at four horizontal locations (i.e., instrument Nests A, B, C, and D) outside, near the edge of, and beneath the barrier. Each instrument nest consists of a capacitance probe with multiple sensors, multiple heat-dissipation units, and a neutron probe access tube used to measure soil-water content and soil-water pressure. Nest A serves as a control by providing subsurface conditions outside the influence of the surface barrier. Nest B provides subsurface measurements to assess barrier edge effects. Nests C and D are used to assess the impact of the surface barrier on soil-moisture conditions beneath it. Monitoring began in September 2006 and continues to the present. To date, the monitoring system has provided high-quality data. Results show that the soil beneath the barrier has been draining from the shallower depth. The lack of climate-caused seasonal variation of soil water condition beneath the barrier indicates that the surface barrier has minimized water exchange between the soil and the atmosphere.

  8. The Effects of Fire on the Function of the 200-BP-1 Engineered Surface Barrier

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Anderson L.; Link, Steven O.; Hasan, Nazmul; Draper, Kathryn E.

    2009-09-01

    A critical unknown in use of barrier technology for long-term waste isolation is performance after a major disturbance especially when institutional controls are intact, but there are no resources to implement corrective actions. The objective of this study was to quantify the effects of wild fire on alterations the function of an engineered barrier. A controlled burn September 26, 2008 was used to remove all the vegetation from the north side of the barrier. Flame heights exceeded 9 m and temperatures ranged from 250 oC at 1.5 cm below the surface to over 700 oC at 1 m above the surface. Post-fire analysis of soil properties show significant decreases in wettability, hydraulic conductivity, air entry pressure, organic matter, and porosity relative to pre-fire conditions whereas dry bulk density increased. Decreases in hydraulic conductivity and wettabilty immediately after the fire are implicated in a surface runoff event that occurred in January 2009, the first in 13 years. There was a significant increase in macro-nutrients, pH, and electrical conductivity. After one year, hydrophobicity has returned to pre-burn levels with only 16% of samples still showing signs of decreased wettability. Over the same period, hydraulic conductivity and air entry pressure returned to pre-burn levels at one third of the locations but remained identical to values recorded immediately after the fire at the other two thirds. Soil nutrients, pH, and electrical conductivity remain elevated after 1 year. Species composition on the burned surface changed markedly from prior years and relative to the unburned surface and two analog sites. An increase in the proportion of annuals and biennials is characteristic of burned surfaces that have become dominated by ruderal species. Greenhouse seedling emergence tests conducted to assess the seed bank of pre- and post-burn soils and of two analog sites at the McGee Ranch show no difference in the number of species emerging from soils collected

  9. The strain effect in the surface barrier structures prepared on the basis of n-Si and p-Si

    International Nuclear Information System (INIS)

    Mamatkarimov, O.O.; Tuychiev, U.A.

    2004-01-01

    Full text: One of the ways of creation of large deformations in small volume of the semiconductor is the deformation created by a needle. At insignificant change of external influence the large deformation under a needle in small volume of the semiconductor the significant change of electrophysical parameters of the semiconductor in small volume is created. Therefore, in the present work the results of researches of local pressure influence on physical properties of surface barrier structures has been performed on the basis of silicon with Ni and Mn impurity. The relative changes of a direct current made on the basis n-Si and p-Si from a different degree of compensation are given depending on size of local pressure are shown. Change of current in structures Au-Si -Sb with specific resistance of base ρ=80 Ω·cm and ρ=200 Ω·cm are I p /I 0 =3-3.5 times and I P /I ) =2-2.5 times at pressure P=1.6·10 8 Pa respectively. These data show, that in structures received on the basis of initial silicon, change of a direct current with pressure is in inverse proportion to size of resistance of base of the diode. And in structures Au-Si -Sb with specific resistance of base ρ=5·10 2 Ω·cm and ρ=3·10 3 Ω·cm these changes accordingly are I P /I 0 =7 and I P /I 0 =14. Changes of direct current relative to initial value for structures on the basis p-Si with specific resistance ρ=7·10 2 Ω·cm and ρ=4·10 3 Ω·cm) are I P /I 0 =9 and I P /I 0 =16 respectively. The same changes of direct current of structures on the basis P-Si at local pressure are I P /I 0 =2-2.5. The given values I P /I 0 testify that as in structures Au-Si -Sb, and structures Sb-p-Si -Au, unlike structures on the basis of initial silicon, the values I P /I 0 are increased with increase of specific resistance of base of structures

  10. Edge effect on weevils and spiders

    Directory of Open Access Journals (Sweden)

    R. Horváth

    2002-05-01

    Full Text Available The edge effect on weevils and spiders was tested along oak forest – meadow transects using sweep-net samples at the Síkfökút Project in Hungary. For spiders the species richness was significantly higher in the forest edge than either in the meadow or the forest interior. For weevils the species richness of the forest edge was higher than that of the meadow, but the difference was not statistically significant whereas the species richness of the forest interior was significantly lower than that of the forest edge and the meadow. The composition of the spider assemblage of the edge was more similar to the forest, while the composition of weevils in the edge was more similar to the meadow. Our results based on two invertebrate groups operating on different trophic levels suggest that there is a significant edge effect for the studied taxa resulting in higher species richness in the edge.

  11. Development of edge effects around experimental ecosystem hotspots is affected by edge density and matrix type

    Science.gov (United States)

    Ecological edge effects are sensitive to landscape context. In particular, edge effects can be altered by matrix type and by the presence of other nearby edges. We experimentally altered patch configurations in an African savanna to determine how edge density and matrix type influence edge effect de...

  12. Ab initio transport across bismuth selenide surface barriers

    KAUST Repository

    Narayan, Awadhesh

    2014-11-24

    © 2014 American Physical Society. We investigate the effect of potential barriers in the form of step edges on the scattering properties of Bi2Se3(111) topological surface states by means of large-scale ab initio transport simulations. Our results demonstrate the suppression of perfect backscattering, while all other scattering processes, which do not entail a complete spin and momentum reversal, are allowed. Furthermore, we find that the spin of the surface state develops an out-of-plane component as it traverses the barrier. Our calculations reveal the existence of quasibound states in the vicinity of the surface barriers, which appear in the form of an enhanced density of states in the energy window corresponding to the topological state. For double barriers we demonstrate the formation of quantum well states. To complement our first-principles results we construct a two-dimensional low-energy effective model and illustrate its shortcomings. Our findings are discussed in the context of a number of recent experimental works.

  13. Edge effect on weevils and spiders

    OpenAIRE

    Horváth, R.; Magura, T.; Péter, G.; Tóthmérész, B.

    2002-01-01

    The edge effect on weevils and spiders was tested along oak forest – meadow transects using sweep-net samples at the Síkfökút Project in Hungary. For spiders the species richness was significantly higher in the forest edge than either in the meadow or the forest interior. For weevils the species richness of the forest edge was higher than that of the meadow, but the difference was not statistically significant whereas the species richness of the forest...

  14. Predicted solar cell edge radiation effects

    International Nuclear Information System (INIS)

    Gates, M.T.

    1993-01-01

    The Advanced Solar Cell Orbital Test (ASCOT) will test six types of solar cells in a high energy proton environment. During the design of the experiment a question was raised about the effects of proton radiation incident on the edge of the solar cells and whether edge radiation shielding was required. Historical geosynchronous data indicated that edge radiation damage is not detectable over the normal end of life solar cell degradation; however because the ASCOT radiation environment has a much higher and more energetic fluence of protons, considerably more edge damage is expected. A computer analysis of the problem was made by modeling the expected radiation damage at the cell edge and using a network model of small interconnected solar cells to predict degradation in the cell's electrical output. The model indicated that the deepest penetration of edge radiation was at the top of the cell near the junction where the protons have access to the cell through the low density cell/cover adhesive layer. The network model indicated that the cells could tolerate high fluences at their edge as long as there was high electrical resistance between the edge radiated region and the contact system on top of the cell. The predicted edge radiation related loss was less than 2% of maximum power for GaAs/Ge solar cells. As a result, no edge radiation protection was used for ASCOT

  15. Permanent isolation surface barrier: Functional performance

    International Nuclear Information System (INIS)

    Wing, N.R.

    1993-10-01

    This document presents the functional performance parameters for permanent isolation surface barriers. Permanent isolation surface barriers have been proposed for use at the Hanford Site (and elsewhere) to isolate and dispose of certain types of waste in place. Much of the waste that would be disposed of using in-place isolation techniques is located in subsurface structures, such as solid waste burial grounds, tanks, vaults, and cribs. Unless protected in some way, the wastes could be transported to the accessible environment via transport pathways, such as water infiltration, biointrusion, wind and water erosion, human interference, and/or gaseous release

  16. Edge effect correction using ion beam figuring.

    Science.gov (United States)

    Yang, Bing; Xie, Xuhui; Li, Furen; Zhou, Lin

    2017-11-10

    The edge effect is regarded as one of the most difficult technical issues for fabricating large primary mirrors, as it can greatly reduce the key performance of the optical system. Ion beam figuring (IBF) has the advantage of no edge effect, so we can use it to remove high points on the edge and improve surface accuracy. The edge local correction method (ELCM) of IBF processes only the surface edge zone, and is very different from the current full caliber figuring method (FCFM). Therefore, it is necessary to study the ELCM of IBF. In this paper, the key factors of ELCM are analyzed, such as dwell time algorithm, edge data extension methods, and the outward dimension of the starting figuring point. At the same time, the distinctions between ELCM and FCFM are compared. Finally, a 142 mm diameter fused silica mirror is fabricated to verify the validity of the theoretical of ELCM. The experimental results indicate that the figuring precision and efficiency can be obviously improved by ELCM.

  17. Edge effects in composites by moire interferometry

    Science.gov (United States)

    Czarnek, R.; Post, D.; Herakovich, C.

    1983-01-01

    The very high sensitivity of moire interferometry has permitted the present edge effect experiments to be conducted at a low average stress and strain level, assuring linear and elastic behavior in the composite material samples tested. Sensitivity corresponding to 2450 line/mm moire was achieved with a 0.408 micron/fringe. Simultaneous observations of the specimen face and edge displacement fields showed good fringe definition despite the 1-mm thickness of the specimens and the high gradients, and it is noted that the use of a carrier pattern and optical filtering was effective in even these conditions. Edge effects and dramatic displacement gradients were confirmed in angle-ply composite laminates.

  18. X-point effect on edge stability

    International Nuclear Information System (INIS)

    Saarelma, S; Kirk, A; Kwon, O J

    2011-01-01

    We study the effects of the X-point configuration on edge localized mode (ELM) triggering peeling and ballooning modes using fixed boundary equilibria and modifying the plasma shape to approach the limit of a true X-point. The current driven pure peeling modes are asymptotically stabilized by the X-point while the stabilizing effect on ballooning modes depends on the poloidal location of the X-point. The coupled peeling-ballooning modes experience the elimination of the peeling component as the X-point is introduced. This can significantly affect the edge stability diagrams used to analyse the ELM triggering mechanisms.

  19. Prototype Hanford Surface Barrier: Design basis document

    International Nuclear Information System (INIS)

    Myers, D.R.; Duranceau, D.A.

    1994-11-01

    The Hanford Site Surface Barrier Development Program (BDP) was organized in 1985 to develop the technology needed to provide a long-term surface barrier capability for the Hanford Site and other arid sites. This document provides the basis of the prototype barrier. Engineers and scientists have momentarily frozen evolving barrier designs and incorporated the latest findings from BDP tasks. The design and construction of the prototype barrier has required that all of the various components of the barrier be brought together into an integrated system. This integration is particularly important because some of the components of the protective barreir have been developed independently of other barreir components. This document serves as the baseline by which future modifications or other barrier designs can be compared. Also, this document contains the minutes of meeting convened during the definitive design process in which critical decisions affecting the prototype barrier's design were made and the construction drawings

  20. Permanent isolation surface barrier development plan

    International Nuclear Information System (INIS)

    Wing, N.R.

    1994-01-01

    The exhumation and treatment of wastes may not always be the preferred alternative in the remediation of a waste site. In-place disposal alternatives, under certain circumstances, may be the most desirable alternatives to use in the protection of human health and the environment. The implementation of an in-place disposal alternative will likely require some type of protective covering that will provide long-term isolation of the wastes from the accessible environment. Even if the wastes are exhumed and treated, a long-term barrier may still be needed to adequately dispose of the treated wastes or any remaining waste residuals. Currently, no open-quotes provenclose quotes long-term barrier is available. The Hanford Site Permanent Isolation Surface Barrier Development Program (BDP) was organized to develop the technology needed to provide a long-term surface barrier capability for the Hanford Site. The permanent isolation barrier technology also could be used at other sites. Permanent isolation barriers use engineered layers of natural materials to create an integrated structure with redundant protective features. Drawings of conceptual permanent isolation surface barriers are shown. The natural construction materials (e.g., fine soil, sand, gravel, riprap, asphalt) have been selected to optimize barrier performance and longevity. The objective of current designs is to use natural materials to develop a maintenance-free permanent isolation surface barrier that isolates wastes for a minimum of 1,000 years by limiting water drainage to near-zero amounts; reducing the likelihood of plant, animal, and human intrusion; controlling the exhalation of noxious gases; and minimizing erosion-related problems

  1. Permanent isolation surface barrier development plan

    Energy Technology Data Exchange (ETDEWEB)

    Wing, N.R.

    1994-01-01

    The exhumation and treatment of wastes may not always be the preferred alternative in the remediation of a waste site. In-place disposal alternatives, under certain circumstances, may be the most desirable alternatives to use in the protection of human health and the environment. The implementation of an in-place disposal alternative will likely require some type of protective covering that will provide long-term isolation of the wastes from the accessible environment. Even if the wastes are exhumed and treated, a long-term barrier may still be needed to adequately dispose of the treated wastes or any remaining waste residuals. Currently, no {open_quotes}proven{close_quotes} long-term barrier is available. The Hanford Site Permanent Isolation Surface Barrier Development Program (BDP) was organized to develop the technology needed to provide a long-term surface barrier capability for the Hanford Site. The permanent isolation barrier technology also could be used at other sites. Permanent isolation barriers use engineered layers of natural materials to create an integrated structure with redundant protective features. Drawings of conceptual permanent isolation surface barriers are shown. The natural construction materials (e.g., fine soil, sand, gravel, riprap, asphalt) have been selected to optimize barrier performance and longevity. The objective of current designs is to use natural materials to develop a maintenance-free permanent isolation surface barrier that isolates wastes for a minimum of 1,000 years by limiting water drainage to near-zero amounts; reducing the likelihood of plant, animal, and human intrusion; controlling the exhalation of noxious gases; and minimizing erosion-related problems.

  2. Plasma measurements with surface barrier detectors

    International Nuclear Information System (INIS)

    Futch, A.H. Jr.; Bradley, A.E.

    1969-01-01

    A surface barrier detector system for measuring the loss rate of protons from a hydrogen plasma and their energy spectrum is described. A full width at half maximum (FWHM) resolution of 1.4 keV for 15-keV hydrogen atoms was obtained using a selected detector having a sensitive area of 3 mm 2 and a depletion depth of 700 microns

  3. Zone edge effects with variable rate irrigation

    Science.gov (United States)

    Variable rate irrigation (VRI) systems may offer solutions to enhance water use efficiency by addressing variability within a field. However, the design of VRI systems should be considered to maximize application uniformity within sprinkler zones, while minimizing edge effects between such zones alo...

  4. Long-Term Drainage from the Riprap Side Slope of a Surface Barrier

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhuanfang

    2017-07-01

    Surface barriers designed to isolate underground nuclear waste in place are expected to function for at least 1000 years. To achieve this long design life, such barriers need to be protected with side slopes against wind- and water-induced erosion and damage by natural or human activities. However, the side slopes are usually constructed with materials coarser than the barrier. Their hydrological characteristics must be understood so that any drainage from them is considered in the barrier design and will not compromise the barrier function. The Prototype Hanford Barrier, an evapotranspiration-capillary (ETC) barrier, was constructed in 1994 at the Hanford Site in southeastern Washington state, with a gravel side slope and a riprap side slope. The soil water content in the gravel side slope and drainage from both side slopes have been monitored since the completion of construction. The monitoring results show that under natural precipitation the annual drainage rates from the two types of side slopes were very similar and about 5 times the typical recharge from local soil with natural vegetation and 40 times the barrier design criterion. The higher recharge from the side slopes results in some of the drainage migrating laterally to the region beneath the ETC barrier. This edge effect of the enhanced drainage was evaluated for a period of 1000 years by numerical simulation. The edge effect was quantified by the amount of water across the barrier edges and the affecting distance of the barrier edges. These results indicate that design features can be adjusted to reduce the edge effect when necessary.

  5. Edge-effect interactions in fragmented and patchy landscapes.

    Science.gov (United States)

    Porensky, Lauren M; Young, Truman P

    2013-06-01

    Ecological edges are increasingly recognized as drivers of landscape patterns and ecosystem processes. In fragmented and patchy landscapes (e.g., a fragmented forest or a savanna with scattered termite mounds), edges can become so numerous that their effects pervade the entire landscape. Results of recent studies in such landscapes show that edge effects can be altered by the presence or proximity of other nearby edges. We considered the theoretical significance of edge-effect interactions, illustrated various landscape configurations that support them and reviewed existing research on this topic. Results of studies from a variety of locations and ecosystem types show that edge-effect interactions can have significant consequences for ecosystems and conservation, including higher tree mortality rates in tropical rainforest fragments, reduced bird densities in grassland fragments, and bush encroachment and reduced wildlife densities in a tropical savanna. To clarify this underappreciated concept and synthesize existing work, we devised a conceptual framework for edge-effect interactions. We first worked to reduce terminological confusion by clarifying differences among terms such as edge intersection and edge interaction. For cases in which nearby edge effects interact, we proposed three possible forms of interaction: strengthening (presence of a second edge causes stronger edge effects), weakening (presence of a second edge causes weaker edge effects), and emergent (edge effects change completely in the presence of a second edge). By clarifying terms and concepts, this framework enables more precise descriptions of edge-effect interactions and facilitates comparisons of results among disparate study systems and response variables. A better understanding of edge-effect interactions will pave the way for more appropriate modeling, conservation, and management in complex landscapes. © 2013 Society for Conservation Biology.

  6. The effect of defocus on edge contrast sensitivity

    NARCIS (Netherlands)

    Jansonius, NM; Kooijman, AC

    The effect of optical blur (defocus) on edge contrast sensitivity was studied. Edge contrast sensitivity detoriates with fairly small amounts of blur (similar to 0.5 D) and is roughly reduced by half for each dioptre of blur. The effect of blur on edge contrast sensitivity equals the effect of blur

  7. Suppression of surface barriers in superconductors by columnar defects

    International Nuclear Information System (INIS)

    Koshelev, A. E.; Vinokur, V. M.

    2001-01-01

    We investigate the influence of columnar defects in layered superconductors on the thermally activated penetration of pancake vortices through the surface barrier. Columnar defects, located near the surface, facilitate penetration of vortices through the surface barrier, by creating ''weak spots,'' through which pancakes can penetrate into the superconductor. Penetration of a pancake mediated by an isolated column, located near the surface, is a two-stage process involving hopping from the surface to the column and the detachment from the column into the bulk; each stage is controlled by its own activation barrier. The resulting effective energy is equal to the maximum of those two barriers. For a given external field there exists an optimum location of the column for which the barriers for the both processes are equal and the reduction of the effective penetration barrier is maximal. At high fields the effective penetration field is approximately 2 times smaller than in unirradiated samples. We also estimate the suppression of the effective penetration field by column clusters. This mechanism provides further reduction of the penetration field at low temperatures

  8. Forests on the edge: Microenvironmental drivers of carbon cycle response to edge effects

    Science.gov (United States)

    Reinmann, A.; Hutyra, L.; Smith, I. A.; Thompson, J.

    2017-12-01

    Twenty percent of the world's forest is within 100 m of a forest edge, but much of our understanding of forest carbon (C) cycling comes from large, intact ecosystems, which creates an important mismatch between the landscapes we study and those we aim to characterize. The temperate broadleaf forest is the most heavily fragmented forest biome in the world and its growth and carbon storage responses to forest edge effects appear to be the opposite of those in the tropical and boreal regions. We used field measurements to quantify the drivers of temperate forest C cycling response to edge effects, characterizing vegetative growth, respiration, and forest structure. We find large gradients in air and soil temperature from the forest interior to edge (up to 4 and 10° C, respectively) and the magnitude of this gradient is inversely correlated to the size of the forest edge growth enhancement. Further, leaf area index increases with proximity to the forest edge. While we also find increases in soil respiration between the forest interior and edge, this flux is small relative to aboveground growth enhancement near the edge. These findings represent an important advancement in our understanding of forest C cycle response to edge effects and will greatly improve our capacity to constrain biogenic C fluxes in fragmented and heterogeneous landscapes.

  9. Research on reducing the edge effect in magnetorheological finishing.

    Science.gov (United States)

    Hu, Hao; Dai, Yifan; Peng, Xiaoqiang; Wang, Jianmin

    2011-03-20

    The edge effect could not be avoided in most optical manufacturing methods based on the theory of computer controlled optical surfacing. The difference between the removal function at the workpiece edge and that inside it is also the primary cause for edge effect in magnetorheological finishing (MRF). The change of physical dimension and removal ratio of the removal function is investigated through experiments. The results demonstrate that the situation is different when MRF "spot" is at the leading edge or at the trailing edge. Two methods for reducing the edge effect are put into practice after analysis of the processing results. One is adopting a small removal function for dealing with the workpiece edge, and the other is utilizing the removal function compensation. The actual processing results show that these two ways are both effective on reducing the edge effect in MRF.

  10. Bulk Versus Edge in the Quantum Hall Effect

    OpenAIRE

    Kao, Y. -C.; Lee, D. -H.

    1996-01-01

    The manifestation of the bulk quantum Hall effect on edge is the chiral anomaly. The chiral anomaly {\\it is} the underlying principle of the ``edge approach'' of quantum Hall effect. In that approach, $\\sxy$ should not be taken as the conductance derived from the space-local current-current correlation function of the pure one-dimensional edge problem.

  11. Collective phenomena in volume and surface barrier discharges

    Science.gov (United States)

    Kogelschatz, U.

    2010-11-01

    Barrier discharges are increasingly used as a cost-effective configuration to produce non-equilibrium plasmas at atmospheric pressure. This way, copious amounts of electrons, ions, free radicals and excited species can be generated without significant heating of the background gas. In most applications the barrier is made of dielectric material. Major applications utilizing mainly dielectric barriers include ozone generation, surface cleaning and modification, polymer and textile treatment, sterilization, pollution control, CO2 lasers, excimer lamps, plasma display panels (flat TV screens). More recent research efforts are devoted to biomedical applications and to plasma actuators for flow control. Sinusoidal feeding voltages at various frequencies as well as pulsed excitation schemes are used. Volume as well as surface barrier discharges can exist in the form of filamentary, regularly patterned or diffuse, laterally homogeneous discharges. The physical effects leading to collective phenomena in volume and surface barrier discharges are discussed in detail. Special attention is paid to self-organization of current filaments and pattern formation. Major similarities of the two types of barrier discharges are elaborated.

  12. Size effect model for the edge strength of glass with cut and ground edge finishing

    NARCIS (Netherlands)

    Vandebroek, M.; Louter, C.; Caspeele, R.; Ensslen, F.; Belis, J.L.I.F.

    2014-01-01

    The edge strength of glass is influenced by the size of the surface (near the edge) which is subjected to tensile stresses. To quantify this size effect, 8 series of single layer annealed glass beam specimens (as-received glass) were subjected to in-plane four-point bending with linearly increased

  13. Beta dosimetry with surface barrier detectors

    International Nuclear Information System (INIS)

    Heinzelmann, M.F.M.; Schuren, H.; Dreesen, K.

    1980-01-01

    A small dosimeter to measure the dose rate due to β-radiation in an energy independent fashion is described in detail. A surface barrier semi-conductor detector is used whose thickness of sensitive layer is changed by varying the detector voltage. The integral count rate can then be determined as a function of applied voltage and discrimination thresholds. The integral count rate can be related to β dose rate in an energy independent fashion only for a time constant of 0.25 μs. However, the use of a single channel analyzer permits an energy-independent determination of the β-dose rate with 0.25 or 0.5 μs time constants. The sensitivity of the device as a function of dose rate is investigation up to 600 rad/hr. Furthermore, the sensitivity of the device at a constant dose rate was shown to be uniform up to a dose of 50,000 rads. (UK)

  14. Balancing the edge effects budget: bay scallop settlement and loss along a seagrass edge.

    Science.gov (United States)

    Carroll, John M; Furman, Bradley T; Tettelbach, Stephen T; Peterson, Bradley J

    2012-07-01

    Edge effects are a dominant subject in landscape ecology literature, yet they are highly variable and poorly understood. Often, the literature suggests simple models for edge effects-positive (enhancement at the edge), negative (enhancement at the interior), or no effect (neutral)--on a variety of metrics, including abundance, diversity, and mortality. In the marine realm, much of this work has focused on fragmented seagrass habitats due to their importance for a variety of commercially important species. In this study, the settlement, recruitment, and survival of bay scallops was investigated across a variety of seagrass patch treatments. By simultaneously collecting settlers (those viable larvae available to settle and metamorphose) and recruits (those settlers that survive some period of time, in this case, 6 weeks) on the same collectors, we were able to demonstrate a "balance" between positive and negative edge effects, resulting in a net neutral effect. Scallop settlement was significantly enhanced along seagrass edges, regardless of patch type while survival was elevated within patch interiors. However, recruitment (the net result of settlement and post-settlement loss) did not vary significantly from edge to center, representing a neutral effect. Further, results suggest that post-settlement loss, most likely due to predation, appears to be the dominant mechanism structuring scallop abundance, not patterns in settlement. These data illustrate the complexity of edge effects, and suggest that the metric used to investigate the effect (be it abundance, survival, or other metrics) can often influence the magnitude and direction of the perceived effect. Traditionally, high predation along a habitat edge would have indicated an "ecological trap" for the species in question; however, this study demonstrates that, at the population level, an ecological trap may not exist.

  15. Surface barrier research at the Hanford Site

    International Nuclear Information System (INIS)

    Gee, G.W.; Ward, A.L.; Fayer, M.J.

    1997-01-01

    At the DOE Hanford Site, a field-scale prototype surface barrier was constructed in 1994 over an existing waste site as a part of a CERCLA treatability test. The above-grade barrier consists of a fine-soil layer overlying coarse layers of sands, gravels, basalt rock (riprap), and a low permeability asphalt layer. Two sideslope configurations, clean-fill gravel on a 10:1 slope and basalt riprap on a 2:1 slope, were built and are being tested. Design considerations included: constructability; drainage and water balance monitoring, wind and water erosion control and monitoring; surface revegetation and biotic intrusion; subsidence and sideslope stability, and durability of the asphalt layer. The barrier is currently in the final year of a three-year test designed to answer specific questions related to stability and long-term performance. One half of the barrier is irrigated such that the total water applied, including precipitation, is 480 mm/yr (three times the long-term annual average). Each year for the past two years, an extreme precipitation event (71 mm in 8 hr) representing a 1,000-yr return storm was applied in late March, when soil water storage was at a maximum. While the protective sideslopes have drained significant amounts of water, the soil cover (2-m of silt-loam soil overlying coarse sand and rock) has never drained. During the past year there was no measurable surface runoff or wind erosion. This is attributed to extensive revegetation of the surface. In addition, the barrier elevation has shown a small increase of 2 to 3 cm that is attributed to a combination of root proliferation and freeze/thaw activity. Testing will continue through September 1997. Performance data from the prototype barrier will be used by DOE in site-closure decisions at Hanford

  16. Edge states in quantum Hall effect in graphene

    International Nuclear Information System (INIS)

    Gusynin, V.P.; Miransky, V.A.; Sharapov, S.G.; Shovkovy, I.A.

    2008-01-01

    We review recent results concerning the spectrum of edge states in the quantum Hall effect in graphene. In particular, special attention is paid to the derivation of the conditions under which gapless edge states exist in the spectrum of graphene with 'zigzag' and 'armchair' edges. It is found that in the case of a half-plane or a ribbon with zigzag edges, there are gapless edge states only when a spin gap dominates over a Dirac mass gap. In the case of a half-plane with an armchair edge, the existence of the gapless edge states depends on the specific type of Dirac mass gaps. The implications of these results for the dynamics in the quantum Hall effect in graphene are discussed

  17. Urbanization Impacts on Mammals across Urban-Forest Edges and a Predictive Model of Edge Effects

    OpenAIRE

    Villaseñor, Nélida R.; Driscoll, Don A.; Escobar, Martín A. H.; Gibbons, Philip; Lindenmayer, David B.

    2014-01-01

    With accelerating rates of urbanization worldwide, a better understanding of ecological processes at the wildland-urban interface is critical to conserve biodiversity. We explored the effects of high and low-density housing developments on forest-dwelling mammals. Based on habitat characteristics, we expected a gradual decline in species abundance across forest-urban edges and an increased decline rate in higher contrast edges. We surveyed arboreal mammals in sites of high and low housing den...

  18. Edge effect modeling of small tool polishing in planetary movement

    Science.gov (United States)

    Li, Qi-xin; Ma, Zhen; Jiang, Bo; Yao, Yong-sheng

    2018-03-01

    As one of the most challenging problems in Computer Controlled Optical Surfacing (CCOS), the edge effect greatly affects the polishing accuracy and efficiency. CCOS rely on stable tool influence function (TIF), however, at the edge of the mirror surface,with the grinding head out of the mirror ,the contact area and pressure distribution changes, which resulting in a non-linear change of TIF, and leads to tilting or sagging at the edge of the mirror. In order reduce the adverse effects and improve the polishing accuracy and efficiency. In this paper, we used the finite element simulation to analyze the pressure distribution at the mirror edge and combined with the improved traditional method to establish a new model. The new method fully considered the non-uniformity of pressure distribution. After modeling the TIFs in different locations, the description and prediction of the edge effects are realized, which has a positive significance on the control and suppression of edge effects

  19. Collective Phenomena In Volume And Surface Barrier Discharges

    Science.gov (United States)

    Kogelschatz, U.

    2010-07-01

    Barrier discharges are increasingly used as a cost-effective means to produce non-equilibrium plasmas at atmospheric pressure. This way, copious amounts of electrons, ions, free radicals and excited species can be generated without appreciable gas heating. In most applications the barrier is made of dielectric material. In laboratory experiments also the use of resistive, ferroelectric and semiconducting materials has been investigated, also porous ceramic layers and dielectric barriers with controlled surface conductivity. Major applications utilizing mainly dielectric barriers include ozone generation, surface cleaning and modification, polymer and textile treatment, sterilization, pollution control, CO2 lasers, excimer lamps, plasma display panels (flat TV screens). More recent research efforts are also devoted to biomedical applications and to plasma actuators for flow control. Sinu- soidal feeding voltages at various frequencies as well as pulsed excitation schemes are used. Volume as well as surface barrier discharges can exist in the form of filamentary, regularly patterned or laterally homogeneous discharges. Reviews of the subject and the older literature on barrier discharges were published by Kogelschatz (2002, 2003), by Wagner et al. (2003) and by Fridman et al. (2005). A detailed discussion of various properties of barrier discharges can also be found in the recent book "Non-Equilibrium Air Plasmas at Atmospheric Pressure" by Becker et al. (2005). The physical effects leading to collective phenomena in volume and surface barrier discharges will be discussed in detail. Special attention will be given to self-organization of current filaments. Main similarities and differences of the two types of barrier discharges will be elaborated.

  20. Urbanization impacts on mammals across urban-forest edges and a predictive model of edge effects.

    Science.gov (United States)

    Villaseñor, Nélida R; Driscoll, Don A; Escobar, Martín A H; Gibbons, Philip; Lindenmayer, David B

    2014-01-01

    With accelerating rates of urbanization worldwide, a better understanding of ecological processes at the wildland-urban interface is critical to conserve biodiversity. We explored the effects of high and low-density housing developments on forest-dwelling mammals. Based on habitat characteristics, we expected a gradual decline in species abundance across forest-urban edges and an increased decline rate in higher contrast edges. We surveyed arboreal mammals in sites of high and low housing density along 600 m transects that spanned urban areas and areas turn on adjacent native forest. We also surveyed forest controls to test whether edge effects extended beyond our edge transects. We fitted models describing richness, total abundance and individual species abundance. Low-density housing developments provided suitable habitat for most arboreal mammals. In contrast, high-density housing developments had lower species richness, total abundance and individual species abundance, but supported the highest abundances of an urban adapter (Trichosurus vulpecula). We did not find the predicted gradual decline in species abundance. Of four species analysed, three exhibited no response to the proximity of urban boundaries, but spilled over into adjacent urban habitat to differing extents. One species (Petaurus australis) had an extended negative response to urban boundaries, suggesting that urban development has impacts beyond 300 m into adjacent forest. Our empirical work demonstrates that high-density housing developments have negative effects on both community and species level responses, except for one urban adapter. We developed a new predictive model of edge effects based on our results and the literature. To predict animal responses across edges, our framework integrates for first time: (1) habitat quality/preference, (2) species response with the proximity to the adjacent habitat, and (3) spillover extent/sensitivity to adjacent habitat boundaries. This framework will

  1. Urbanization impacts on mammals across urban-forest edges and a predictive model of edge effects.

    Directory of Open Access Journals (Sweden)

    Nélida R Villaseñor

    Full Text Available With accelerating rates of urbanization worldwide, a better understanding of ecological processes at the wildland-urban interface is critical to conserve biodiversity. We explored the effects of high and low-density housing developments on forest-dwelling mammals. Based on habitat characteristics, we expected a gradual decline in species abundance across forest-urban edges and an increased decline rate in higher contrast edges. We surveyed arboreal mammals in sites of high and low housing density along 600 m transects that spanned urban areas and areas turn on adjacent native forest. We also surveyed forest controls to test whether edge effects extended beyond our edge transects. We fitted models describing richness, total abundance and individual species abundance. Low-density housing developments provided suitable habitat for most arboreal mammals. In contrast, high-density housing developments had lower species richness, total abundance and individual species abundance, but supported the highest abundances of an urban adapter (Trichosurus vulpecula. We did not find the predicted gradual decline in species abundance. Of four species analysed, three exhibited no response to the proximity of urban boundaries, but spilled over into adjacent urban habitat to differing extents. One species (Petaurus australis had an extended negative response to urban boundaries, suggesting that urban development has impacts beyond 300 m into adjacent forest. Our empirical work demonstrates that high-density housing developments have negative effects on both community and species level responses, except for one urban adapter. We developed a new predictive model of edge effects based on our results and the literature. To predict animal responses across edges, our framework integrates for first time: (1 habitat quality/preference, (2 species response with the proximity to the adjacent habitat, and (3 spillover extent/sensitivity to adjacent habitat boundaries. This

  2. Edge effects on the electronic properties of phosphorene nanoribbons

    International Nuclear Information System (INIS)

    Peng, Xihong; Copple, Andrew; Wei, Qun

    2014-01-01

    Two dimensional few-layer black phosphorus crystal structures have recently been fabricated and have demonstrated great potential in electronic applications. In this work, we employed first principles density functional theory calculations to study the edge and quantum confinement effects on the electronic properties of the phosphorene nanoribbons (PNR). Different edge functionalization groups, such as H, F, Cl, OH, O, S, and Se, in addition to a pristine case were studied for a series of ribbon widths up to 3.5 nm. It was found that the armchair-PNRs (APNRs) are semiconductors for all edge groups considered in this work. However, the zigzag-PNRs (ZPNRs) show either semiconductor or metallic behavior in dependence on their edge chemical species. Family 1 edges (i.e., H, F, Cl, OH) form saturated bonds with P atoms in the APNRs and ZPNRs, and the edge states keep far away from the band gap. However, Family 2 edges (pristine, O, S, Se) form weak unsaturated bonds with the p z orbital of the phosphorus atoms and bring edge states within the band gap of the ribbons. For the ZPNRs, the edge states of Family 2 are present around the Fermi level within the band gap, which close up the band gap of the ZPNRs. For the APNRs, these edge states are located at the bottom of the conduction band and result in a reduced band gap.

  3. Edge effects on the electronic properties of phosphorene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Xihong, E-mail: xihong.peng@asu.edu [School of Letters and Sciences, Arizona State University, Mesa, Arizona 85212 (United States); Copple, Andrew [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Wei, Qun [School of Letters and Sciences, Arizona State University, Mesa, Arizona 85212 (United States); School of Physics and Optoelectronic Engineering, Xidian University, Xi' an 710071 (China)

    2014-10-14

    Two dimensional few-layer black phosphorus crystal structures have recently been fabricated and have demonstrated great potential in electronic applications. In this work, we employed first principles density functional theory calculations to study the edge and quantum confinement effects on the electronic properties of the phosphorene nanoribbons (PNR). Different edge functionalization groups, such as H, F, Cl, OH, O, S, and Se, in addition to a pristine case were studied for a series of ribbon widths up to 3.5 nm. It was found that the armchair-PNRs (APNRs) are semiconductors for all edge groups considered in this work. However, the zigzag-PNRs (ZPNRs) show either semiconductor or metallic behavior in dependence on their edge chemical species. Family 1 edges (i.e., H, F, Cl, OH) form saturated bonds with P atoms in the APNRs and ZPNRs, and the edge states keep far away from the band gap. However, Family 2 edges (pristine, O, S, Se) form weak unsaturated bonds with the p{sub z} orbital of the phosphorus atoms and bring edge states within the band gap of the ribbons. For the ZPNRs, the edge states of Family 2 are present around the Fermi level within the band gap, which close up the band gap of the ZPNRs. For the APNRs, these edge states are located at the bottom of the conduction band and result in a reduced band gap.

  4. Understanding the edge effect in wetting: a thermodynamic approach.

    Science.gov (United States)

    Fang, Guoping; Amirfazli, A

    2012-06-26

    Edge effect is known to hinder spreading of a sessile drop. However, the underlying thermodynamic mechanisms responsible for the edge effect still is not well-understood. In this study, a free energy model has been developed to investigate the energetic state of drops on a single pillar (from upright frustum to inverted frustum geometries). An analysis of drop free energy levels before and after crossing the edge allows us to understand the thermodynamic origin of the edge effect. In particular, four wetting cases for a drop on a single pillar with different edge angles have been determined by understanding the characteristics of FE plots. A wetting map describing the four wetting cases is given in terms of edge angle and intrinsic contact angle. The results show that the free energy barrier observed near the edge plays an important role in determining the drop states, i.e., (1) stable or metastable drop states at the pillar's edge, and (2) drop collapse by liquid spilling over the edge completely or staying at an intermediate sidewall position of the pillar. This thermodynamic model presents an energetic framework to describe the functioning of the so-called "re-entrant" structures. Results show good consistency with the literature and expand the current understanding of Gibbs' inequality condition.

  5. Tank Farm Interim Surface Barrier Materials And Runoff Alternatives Study

    International Nuclear Information System (INIS)

    Holm, M.J.

    2009-01-01

    This report identifies candidate materials and concepts for interim surface barriers in the single-shell tank farms. An analysis of these materials for application to the TY tank farm is also provided.

  6. Effective Hamiltonian for protected edge states in graphene

    International Nuclear Information System (INIS)

    Winkler, R.; Deshpande, H.

    2017-01-01

    Edge states in topological insulators (TIs) disperse symmetrically about one of the time-reversal invariant momenta Λ in the Brillouin zone (BZ) with protected degeneracies at Λ. Commonly TIs are distinguished from trivial insulators by the values of one or multiple topological invariants that require an analysis of the bulk band structure across the BZ. We propose an effective two-band Hamiltonian for the electronic states in graphene based on a Taylor expansion of the tight-binding Hamiltonian about the time-reversal invariant M point at the edge of the BZ. This Hamiltonian provides a faithful description of the protected edge states for both zigzag and armchair ribbons, though the concept of a BZ is not part of such an effective model. In conclusion, we show that the edge states are determined by a band inversion in both reciprocal and real space, which allows one to select Λ for the edge states without affecting the bulk spectrum.

  7. High-resolution investigations of edge effects in neutron imaging

    International Nuclear Information System (INIS)

    Strobl, M.; Kardjilov, N.; Hilger, A.; Kuehne, G.; Frei, G.; Manke, I.

    2009-01-01

    Edge enhancement is the main effect measured by the so-called inline or propagation-based neutron phase contrast imaging method. The effect has originally been explained by diffraction, and high spatial coherence has been claimed to be a necessary precondition. However, edge enhancement has also been found in conventional imaging with high resolution. In such cases the effects can produce artefacts and hinder quantification. In this letter the edge effects at cylindrical shaped samples and long straight edges have been studied in detail. The enhancement can be explained by refraction and total reflection. Using high-resolution imaging, where spatial resolutions better than 50 μm could be achieved, refraction and total reflection peaks - similar to diffraction patterns - could be separated and distinguished.

  8. Effect of surface wettability on microfluidic EDGE emulsification

    NARCIS (Netherlands)

    Maan, A.A.; Sahin, S.; Mujawar, L.H.; Boom, R.M.; Schroen, C.G.P.H.

    2013-01-01

    The effect of wettability on microfluidic EDGE emulsification was investigated at dispersed phase contact angles between 90 and 160. The highest contact angle (160) produced monodispersed emulsions with droplet size 5.0 lm and coefficient of variation

  9. Effect of random edge failure on the average path length

    Energy Technology Data Exchange (ETDEWEB)

    Guo Dongchao; Liang Mangui; Li Dandan; Jiang Zhongyuan, E-mail: mgliang58@gmail.com, E-mail: 08112070@bjtu.edu.cn [Institute of Information Science, Beijing Jiaotong University, 100044, Beijing (China)

    2011-10-14

    We study the effect of random removal of edges on the average path length (APL) in a large class of uncorrelated random networks in which vertices are characterized by hidden variables controlling the attachment of edges between pairs of vertices. A formula for approximating the APL of networks suffering random edge removal is derived first. Then, the formula is confirmed by simulations for classical ER (Erdoes and Renyi) random graphs, BA (Barabasi and Albert) networks, networks with exponential degree distributions as well as random networks with asymptotic power-law degree distributions with exponent {alpha} > 2. (paper)

  10. An edge index for the quantum spin-Hall effect

    International Nuclear Information System (INIS)

    Prodan, Emil

    2009-01-01

    Quantum spin-Hall systems are topological insulators displaying dissipationless spin currents flowing at the edges of the samples. In contradistinction to the quantum Hall systems where the charge conductance of the edge modes is quantized, the spin conductance is not and it remained an open problem to find the observable whose edge current is quantized. In this paper, we define a particular observable and the edge current corresponding to this observable. We show that this current is quantized and that the quantization is given by the index of a certain Fredholm operator. This provides a new topological invariant that is shown to take the generic values 0 and 2, in line with the Z 2 topological classification of time-reversal invariant systems. The result gives an effective tool for the investigation of the edge structure in quantum spin-Hall systems. Based on a reasonable assumption, we also show that the edge conducting channels are not destroyed by a random edge. (fast track communication)

  11. Edge effect modeling and experiments on active lap processing.

    Science.gov (United States)

    Liu, Haitao; Wu, Fan; Zeng, Zhige; Fan, Bin; Wan, Yongjian

    2014-05-05

    Edge effect is regarded as one of the most difficult technical issues for fabricating large primary mirrors, especially for large polishing tools. Computer controlled active lap (CCAL) uses a large size pad (e.g., 1/3 to 1/5 workpiece diameters) to grind and polish the primary mirror. Edge effect also exists in the CCAL process in our previous fabrication. In this paper the material removal rules when edge effects happen (i.e. edge tool influence functions (TIFs)) are obtained through experiments, which are carried out on a Φ1090-mm circular flat mirror with a 375-mm-diameter lap. Two methods are proposed to model the edge TIFs for CCAL. One is adopting the pressure distribution which is calculated based on the finite element analysis method. The other is building up a parametric equivalent pressure model to fit the removed material curve directly. Experimental results show that these two methods both effectively model the edge TIF of CCAL.

  12. Symmetric airfoil geometry effects on leading edge noise.

    Science.gov (United States)

    Gill, James; Zhang, X; Joseph, P

    2013-10-01

    Computational aeroacoustic methods are applied to the modeling of noise due to interactions between gusts and the leading edge of real symmetric airfoils. Single frequency harmonic gusts are interacted with various airfoil geometries at zero angle of attack. The effects of airfoil thickness and leading edge radius on noise are investigated systematically and independently for the first time, at higher frequencies than previously used in computational methods. Increases in both leading edge radius and thickness are found to reduce the predicted noise. This noise reduction effect becomes greater with increasing frequency and Mach number. The dominant noise reduction mechanism for airfoils with real geometry is found to be related to the leading edge stagnation region. It is shown that accurate leading edge noise predictions can be made when assuming an inviscid meanflow, but that it is not valid to assume a uniform meanflow. Analytic flat plate predictions are found to over-predict the noise due to a NACA 0002 airfoil by up to 3 dB at high frequencies. The accuracy of analytic flat plate solutions can be expected to decrease with increasing airfoil thickness, leading edge radius, gust frequency, and Mach number.

  13. Dynamics of the edge excitations in the FQH effects

    International Nuclear Information System (INIS)

    Wen, X.G.

    1994-01-01

    Fractional quantum Hall effects (FQHE) discovered by Tsui, Stormer and Gossard open a new era in theory of strongly correlated system. In the first time the authors have to completely abandon the theories based on the single-body picture and use an intrinsic many-body theory proposed by Laughlin and others to describe the FQHE. Due to the repulsive interaction, the strongly correlated FQH liquid is an incompressible state despite the first Landau level is only partially filled. All the bulk excitations in the FQH states have finite energy gaps. The FQH states and insulators are similar in the sense that both states have finite energy gap and short ranged electron propagators. Because of this similarity, it is puzzling that the FQH systems apparently have very different transport properties than ordinary insulators. Halperin first point out that the integral quantum Hall (IQH) states contain gapless edge excitations. Although the electronic states in the bulk are localized, the electronic states at the edge of the sample are extended. Therefore the nontrivial transport properties of the IQH states come from the gapless edge excitations. Such an edge transport picture has been supported by many experiments. One also found that the edge excitations in the IQH states are described by a chiral 1D Fermi liquid theory. Here, the authors review the dynamical theory of the edge excitations in the FQH effects

  14. Automatic α-spectrometry using surface barrier detectors

    International Nuclear Information System (INIS)

    Czarwinski, R.; Loessner, V.; Klucke, H.; Krause, J.

    1984-01-01

    A measurement system has been developed for the routine determination of transuranics in biosamples by α-spectrometry. It employs high-resolution surface-barrier detectors and can be operated automatically by means of an integrated CAMAC system. For 241 Am, the minimum detectable activity is 2.4 x 10 -3 Bq. (author)

  15. Silicon surface barrier detectors used for liquid hydrogen density measurement

    Science.gov (United States)

    James, D. T.; Milam, J. K.; Winslett, H. B.

    1968-01-01

    Multichannel system employing a radioisotope radiation source, strontium-90, radiation detector, and a silicon surface barrier detector, measures the local density of liquid hydrogen at various levels in a storage tank. The instrument contains electronic equipment for collecting the density information, and a data handling system for processing this information.

  16. Ab initio transport across bismuth selenide surface barriers

    KAUST Repository

    Narayan, Awadhesh; Rungger, Ivan; Droghetti, Andrea; Sanvito, Stefano

    2014-01-01

    © 2014 American Physical Society. We investigate the effect of potential barriers in the form of step edges on the scattering properties of Bi2Se3(111) topological surface states by means of large-scale ab initio transport simulations. Our results

  17. Surface barrier analysis of semi-insulating and n{sup +}-type GaAs(0 0 1) following passivation with n-alkanethiol SAMs

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Gregory M. [Laboratory for Quantum Semiconductors and Photon-Based BioNanotechnology, Department of Electrical and Computer Engineering, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1 (Canada); Institute for Chemical Process and Environmental Technology, National Research Council of Canada, Ottawa, Ontario, K1A 0R6 (Canada); Bensebaa, Farid [Institute for Chemical Process and Environmental Technology, National Research Council of Canada, Ottawa, Ontario, K1A 0R6 (Canada); Dubowski, Jan J., E-mail: jan.j.dubowski@usherbrooke.ca [Laboratory for Quantum Semiconductors and Photon-Based BioNanotechnology, Department of Electrical and Computer Engineering, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1 (Canada)

    2011-02-15

    The surface Fermi level of semi-insulating and n{sup +}-type GaAs(0 0 1) was determined before and after passivation with n-alkanethiol self-assembled monolayers (SAMs) by X-ray photoelectron spectroscopy. Fermi level positioning was achieved using Au calibration pads integrated directly onto the GaAs surface, prior to SAM deposition, in order to provide a surface equipotential binding energy reference. Fermi level pinning within 50 meV and surface barrier characteristics according to the Advanced Unified Defect Model were observed. Our results demonstrate the effectiveness of the Au integration technique for the determination of band-edge referenced Fermi level positions and are relevant to an understanding of emerging technologies based on the molecular-semiconductor junction.

  18. Edge Effects and Ecological Traps: Effects on Shrubland Birds in Missouri

    Science.gov (United States)

    April A. Woodward; Alix D. Fink; Frank R. Thompson III

    2001-01-01

    The effect of habitat edge on avian nesting success has been the focus of considerable debate. We studied relationships between habitat edges, locations of nests, and predation. We tested the ecological trap hypothesis for 5 shrubland bird species in the Missouri Ozarks. We compared habitat selection and daily nest predation rates among 3 distance-to-edge categories....

  19. The effect of edge and impurities sites properties on their localized states in semi-infinite zigzag edged 2D honeycomb graphene sheet

    OpenAIRE

    Ahmed, Maher

    2011-01-01

    In this work, the tridiagonal method is used to distinguish between edges modes and area modes to study the edge sites properties effect on edge localized states of semi-infinite zigzag 2D honeycomb graphene sheet. The results show a realistic behavior for the dependance of edge localized states of zigzag graphene on the edge sites properties which explaining the experimental results of measured local density of states at the edge of graphene, while at the same time removing the inconsistence...

  20. Feasibility of compensating for EUV field edge effects through OPC

    Science.gov (United States)

    Maloney, Chris; Word, James; Fenger, Germain L.; Niroomand, Ardavan; Lorusso, Gian F.; Jonckheere, Rik; Hendrickx, Eric; Smith, Bruce W.

    2014-04-01

    As EUV Lithography (EUVL) continues to evolve, it offers a possible solution to the problems of additional masks and lithography steps that drive up the cost and complexity of 193i multiple patterning. EUVL requires a non-telecentric reflective optical system for operation. This requirement causes EUV specific effects such as shadowing. The absorber physically shadows the reflective multilayer (ML) on an EUV reticle resulting in pattern fidelity degradation. To reduce this degradation, a thinner absorber may help. Yet, as the absorber thickness decreases, reflectivity increases in the `dark' region around the image field, resulting in a loss of contrast. The region around the edge of the die on the mask of unpatterned absorber material deposited on top of ML, known as the image border, is also susceptible to undesirable reflections in an ideally dark region. For EUVL to be enabled for high-volume manufacturing (HVM), reticle masking (REMA) blades are used to shield light from the image border to allow for the printing of densely spaced die. When die are printed densely, the image border of each neighboring die will overlap with the edge of a given die resulting in an increase of dose that overexposes features at the edge of the field. This effect is convolved with a fingerprint from the edge of the REMA blades. This phenomenon will be referred to as a field edge effect. One such mitigation strategy that has been investigated to reduce the field edge effect is to fully remove the ML along the image border to ensure that no actinic-EUV radiation can be reflected onto neighboring die. This has proven to suppress the effect, but residual out-of-band radiation still provides additional dose to features near the image border, especially in the corners where three neighboring fields overlap. Measurements of dense contact holes (CHs) have been made along the image border with and without a ML-etched border at IMEC in collaboration with Micron using the ASML NXE:3100. The

  1. Charged particle discrimination with silicon surface barrier detectors

    International Nuclear Information System (INIS)

    Coote, G.E.; Pithie, J.; Vickridge, I.C.

    1996-01-01

    The application for materials analysis of nuclear reactions that give rise to charged particles is a powerful surface analytical and concentration depth profiling technique. Spectra of charged particles, with energies in the range 0.1 to 15 MeV, emitted from materials irradiated with beams of light nuclei such as deuterons are measured with silicon surface barrier detectors. The spectra from multi-elemental materials typically encountered in materials research are usually composed of an overlapping superposition of proton, alpha, and other charged particle spectra. Interpretation of such complex spectra would be simplified if a means were available to electronically discriminate between the detector response to the different kinds of charged particle. We have investigated two methods of discriminating between different types of charged particles. The fast charge pulses from a surface barrier detector have different shapes, depending on the spatial distribution of energy deposition of the incident particle. Fast digitisation of the pulses, followed by digital signal processing provides one avenue for discrimination. A second approach is to use a thin transmission detector in front of a thick detector as a detector telescope. For a given incident energy, different types of charged particles will lose different amounts of energy in the thin detector, providing an alternative means of discrimination. We show that both approaches can provide significant simplification in the interpretation of charged particle spectra in practical situations, and suggest that silicon surface barrier detectors having graded electronic properties could provide improved discrimination compared to the current generation of detectors having homogeneous electronic properties. (author).12 refs., 2 tabs., 28 figs

  2. Hanford protoype surface barrier status report: FY 1994

    International Nuclear Information System (INIS)

    Gee, G.W.; Freeman, H.D.; Walters, W.H. Jr.; Ligotke, M.W.; Campbell, M.D.; Ward, A.L.; Link, S.O.; Smith, S.K.; Gilmore, B.G.; Romine, R.A.

    1994-12-01

    A full-scale prototype surface barrier has been constructed at the 200 BP-1 Operable Unit in the 200 East Area of the Hanford Site. The prototype barrier has been built to evaluate design, construction, and performance features of a surface barrier that may be used for in-place disposal of wastes at the Hanford Site. The design basis and construction of the prototype have been documented. A testing and monitoring plan has been published outlining specific tests planned for the prototype. The current report describes initial testing activities conducted in FY 1994 and outlines activities for testing and monitoring at the prototype barrier in the future. Asphalt permeability was tested during construction of the prototype in April and May 1994. Cores taken from the asphalt concrete layer were tested in the laboratory and found to have hydraulic conductivities below 1E-09 cm/s. Field measurements of hydraulic conductivity taken on the asphalt concrete using a specially-designed falling head permeameter were more than ten times higher than those from core tests. The higher values are attributed to transient flow through the permeameter seal. In spite of this difficulty, the more rapid field measurements (1-day tests in the field compared to 3 months in the laboratory) gave values as low as IE-09 cm/s and averaged about IE-08 cm/s. Samples of fluid-applied asphalt material, used as a sealant on the asphalt concrete layer, were. tested in the laboratory and found to have hydraulic conductivities below IE-10 cm/s. Measurements of hydraulic conductivity taken on an adjacent asphalt test pad using a sealed double-ring infiltrometer (SDRI) were initiated in September 1994 and are expected to be completed in November 1994. Construction of the prototype surface barrier was completed in August 1994

  3. Variation in Local-Scale Edge Effects: Mechanisms and landscape Context

    Science.gov (United States)

    Therese M. Donovan; Peter W. Jones; Elizabeth M. Annand; Frank R. Thompson III

    1997-01-01

    Ecological processes near habitat edges often differ from processes away from edges. Yet, the generality of "edge effects" has been hotly debated because results vary tremendously. To understand the factors responsible for this variation, we described nest predation and cowbird distribution patterns in forest edge and forest core habitats on 36 randomly...

  4. Core-edge coupling and the effect of the edge on overall plasma performance

    International Nuclear Information System (INIS)

    Fichtmueller, M.; Corrigan, G.; Lauro-Taroni, L.

    1999-01-01

    Several attempts to model the entire plasma cross section have been reported in the last few years. Two possibilities are to either couple a core code to a scrape-off layer (SOL) code at a specified interface or to extend the computational region of an SOL-code all the way to the plasma centre. The most advanced global code is the code COCONUT which is based on the former principle and comprises the Monte-Carlo code NIMBUS, the 2D scrape-off layer code EDGE2D, the core transport code JETTO and the core impurity transport code SANCO. A main feature of COCONUT is its modular structure which ensures a high degree of flexibility and the capability to cover a large range of time-scales. The influence of the SOL on the core is illustrated with a range of global simulations carried out with COCONUT. The simulations show that the primary effect of the SOL is the control of the particle sources and sinks with a secondary effect on plasma dilution, radiation and perhaps pedestal temperatures. (author)

  5. Edge-on gating effect in molecular wires.

    Science.gov (United States)

    Lo, Wai-Yip; Bi, Wuguo; Li, Lianwei; Jung, In Hwan; Yu, Luping

    2015-02-11

    This work demonstrates edge-on chemical gating effect in molecular wires utilizing the pyridinoparacyclophane (PC) moiety as the gate. Different substituents with varied electronic demands are attached to the gate to simulate the effect of varying gating voltages similar to that in field-effect transistor (FET). It was observed that the orbital energy level and charge carrier's tunneling barriers can be tuned by changing the gating group from strong electron acceptors to strong electron donors. The single molecule conductance and current-voltage characteristics of this molecular system are truly similar to those expected for an actual single molecular transistor.

  6. Clusterin Seals the Ocular Surface Barrier in Mouse Dry Eye.

    Science.gov (United States)

    Bauskar, Aditi; Mack, Wendy J; Mauris, Jerome; Argüeso, Pablo; Heur, Martin; Nagel, Barbara A; Kolar, Grant R; Gleave, Martin E; Nakamura, Takahiro; Kinoshita, Shigeru; Moradian-Oldak, Janet; Panjwani, Noorjahan; Pflugfelder, Stephen C; Wilson, Mark R; Fini, M Elizabeth; Jeong, Shinwu

    2015-01-01

    Dry eye is a common disorder caused by inadequate hydration of the ocular surface that results in disruption of barrier function. The homeostatic protein clusterin (CLU) is prominent at fluid-tissue interfaces throughout the body. CLU levels are reduced at the ocular surface in human inflammatory disorders that manifest as severe dry eye, as well as in a preclinical mouse model for desiccating stress that mimics dry eye. Using this mouse model, we show here that CLU prevents and ameliorates ocular surface barrier disruption by a remarkable sealing mechanism dependent on attainment of a critical all-or-none concentration. When the CLU level drops below the critical all-or-none threshold, the barrier becomes vulnerable to desiccating stress. CLU binds selectively to the ocular surface subjected to desiccating stress in vivo, and in vitro to the galectin LGALS3, a key barrier component. Positioned in this way, CLU not only physically seals the ocular surface barrier, but it also protects the barrier cells and prevents further damage to barrier structure. These findings define a fundamentally new mechanism for ocular surface protection and suggest CLU as a biotherapeutic for dry eye.

  7. Directional mass transport in an atmospheric pressure surface barrier discharge.

    Science.gov (United States)

    Dickenson, A; Morabit, Y; Hasan, M I; Walsh, J L

    2017-10-25

    In an atmospheric pressure surface barrier discharge the inherent physical separation between the plasma generation region and downstream point of application reduces the flux of reactive chemical species reaching the sample, potentially limiting application efficacy. This contribution explores the impact of manipulating the phase angle of the applied voltage to exert a level of control over the electrohydrodynamic forces generated by the plasma. As these forces produce a convective flow which is the primary mechanism of species transport, the technique facilitates the targeted delivery of reactive species to a downstream point without compromising the underpinning species generation mechanisms. Particle Imaging Velocimetry measurements are used to demonstrate that a phase shift between sinusoidal voltages applied to adjacent electrodes in a surface barrier discharge results in a significant deviation in the direction of the plasma induced gas flow. Using a two-dimensional numerical air plasma model, it is shown that the phase shift impacts the spatial distribution of the deposited charge on the dielectric surface between the adjacent electrodes. The modified surface charge distribution reduces the propagation length of the discharge ignited on the lagging electrode, causing an imbalance in the generated forces and consequently a variation in the direction of the resulting gas flow.

  8. Clusterin Seals the Ocular Surface Barrier in Mouse Dry Eye.

    Directory of Open Access Journals (Sweden)

    Aditi Bauskar

    Full Text Available Dry eye is a common disorder caused by inadequate hydration of the ocular surface that results in disruption of barrier function. The homeostatic protein clusterin (CLU is prominent at fluid-tissue interfaces throughout the body. CLU levels are reduced at the ocular surface in human inflammatory disorders that manifest as severe dry eye, as well as in a preclinical mouse model for desiccating stress that mimics dry eye. Using this mouse model, we show here that CLU prevents and ameliorates ocular surface barrier disruption by a remarkable sealing mechanism dependent on attainment of a critical all-or-none concentration. When the CLU level drops below the critical all-or-none threshold, the barrier becomes vulnerable to desiccating stress. CLU binds selectively to the ocular surface subjected to desiccating stress in vivo, and in vitro to the galectin LGALS3, a key barrier component. Positioned in this way, CLU not only physically seals the ocular surface barrier, but it also protects the barrier cells and prevents further damage to barrier structure. These findings define a fundamentally new mechanism for ocular surface protection and suggest CLU as a biotherapeutic for dry eye.

  9. Atmospheric Water Harvesting: Role of Surface Wettability and Edge Effect

    KAUST Repository

    Jin, Yong

    2017-06-23

    Atmospheric water is emerging as an important potable water source. The present work experimentally and theoretically investigates water condensation and collection on flat surfaces with contrasting contact angles and contact angle hysteresis (CAH) to elucidate their roles on water mass collection efficiency. The experimental results indicate that a hydrophilic surface promotes nucleation and individual droplets growth, and a surface with a low CAH tends to let a smaller droplet to slide down, but the overall water mass collection efficiency is independent of both surface contact angle and CAH. The experimental results agree well with our theoretical calculations. During water condensation, a balance has to be struck between single droplet growth and droplet density on a surface so as to maintain a constant water droplet surface coverage ratio, which renders the role of both surface wettability and hysteresis insignificant to the ultimate water mass collection. Moreover, water droplets on the edges of a surface grow much faster than those on the non-edge areas and thus dominate the contribution to the water mass collection by the entire surface, directly pointing out the very important role of edge effect on water condensation and collection.

  10. Effect of neutral atoms on tokamak edge plasmas

    International Nuclear Information System (INIS)

    Fueloep, T.; Catto, Peter J.; Helander, P.

    2001-01-01

    Neutral atoms can significantly influence the physics of tokamak edge plasmas, e.g., by affecting the radial electric field and plasma flow there, which may, in turn, be important for plasma confinement. Earlier work [Fueloep et al., Phys. Plasmas 5, 3969 (1998)], assuming short mean-free path neutrals and Pfirsch-Schlueter ions, has shown that the ion-neutral coupling through charge-exchange affects the neoclassical flow velocity significantly. However, the mean-free path of the neutrals is not always small in comparison with the radial scale length of densities and temperatures in the edge pedestal. It is therefore desirable to determine what happens in the limit when the neutral mean-free path is comparable with the scale length. In the present work a self-similar solution for the neutral distribution function allowing for strong temperature and density variation is used, following the analysis of Helander and Krasheninnikov [Phys. Plasmas 3, 226 (1995)]. The self-similar solution is possible if the ratio of the mean-free path to the temperature and density scale length is constant throughout the edge plasma. The resulting neutral distribution function is used to investigate the neutral effects on the ion flow and electrostatic potential as this ratio varies from much less than one to order unity

  11. TECHNICAL BASIS FOR EVALUATING SURFACE BARRIERS TO PROTECT GROUNDWATER FROM DEEP VADOSE ZONE CONTAMINATION

    International Nuclear Information System (INIS)

    Fayer, J.M.; Freedman, V.L.; Ward, A.L.; Chronister, G.B.

    2010-01-01

    The U.S. DOE and its predecessors released nearly 2 trillion liters (450 billion gallons) of contaminated liquid into the vadose zone at the Hanford Site. Some of the contaminants currently reside in the deeper parts of the vadose zone where they are much less accessible to characterization, monitoring, and typical remediation activities. The DOE Richland Operations Office (DOE-RL) prepared a treatability test plan in 2008 to examine remediation options for addressing contaminants in the deep vadose zone; one of the technologies identified was surface barriers (also known as engineered barriers, covers, and caps). In the typical configuration, the contaminants are located relatively close to the surface, generally within 15 m, and thus they are close to the base of the surface barrier. The proximity of the surface barrier under these conditions yielded few concerns about the effectiveness of the barrier at depth, particularly for cases in which the contaminants were in a lined facility. At Hanford, however, some unlined sites have contaminants located well below depths of 15 m. The issue raised about these sites is the degree of effectiveness of a surface barrier in isolating contaminants in the deep vadose zone. Previous studies by Hanford Site and PNNL researchers suggest that surface barriers have the potential to provide a significant degree of isolation of deep vadose zone contaminants. The studies show that the actual degree of isolation is site-specific and depends on many factors, including recharge rates, barrier size, depth of contaminants, geohydrologic properties ofthe sediments, and the geochemical interactions between the contaminants and the sediments. After the DOE-RL treatability test plan was published, Pacific Northwest National Laboratory was contracted to review the information available to support surface barrier evaluation for the deep vadose zone, identify gaps in the information and outcomes necessary to fill the data gaps, and outline

  12. Pile-up and defective pulse rejection by pulse shape discrimination in surface barrier detectors

    International Nuclear Information System (INIS)

    Sjoeland, K.A.; Kristiansson, P.

    1994-01-01

    A technique to reject pile-up pulses and defective tail pulses from surface barrier detectors by the use of pulse shape discrimination is demonstrated. The electronic implementation of the pulse shape discrimination is based upon the zero crossing technique and for data reduction multiparameter techniques are used. The characteristic τ value for pile-up rejection is shown to be less than 56 ns. Its effect on detection limits from tail reduction in Particle Elastic Scattering Analysis (PESA) and pile-up peak suppression is discussed. ((orig.))

  13. Edge reconstruction effect in pristine and H-passivated zigzag silicon carbide nanoribbons.

    Science.gov (United States)

    Lou, Ping

    2011-10-14

    The edge reconstruction effect of the zigzag silicon carbide nanoribbons (zz SiC NRs) to a stable line of alternatively fused seven and five membered rings without and with H passivation have been studied using first principles density functional theory (DFT). The both side's edges of the pristine SiC are respectively terminated by Si and C atoms and are called the Si-edge and the C-edge, respectively. In the un-passivated systems, the C-edge reconstructed (Crc) could effectively lower the edge energy of the system, while the Si-edge reconstructed (Sirc) could raise the edge energy of the system. Thus, the Crc edge is the best edge for the edge reconstruction of the system, while the both edge reconstructed (brc) system is the metastability. Moreover, the brc system has a nonmagnetic metallic state, whereas the Crc system, as well as Sirc system, has a ferromagnetic metallic state. The edge reconstructed destroys the magnetic moment of the corresponding edge atoms. The magnetic moment arises from the unreconstructed zigzag edges. The pristine zz edge system has a ferrimagnetic metallic state. However, in the H-passivated systems, the unreconstructed zigzag edge (zz-H) is the best edge. The Crc-H system is the metastability. The Sirc-H system has only slightly higher energy than the Crc-H system, whereas the brc-H system of the pristine SiC NR has the highest edge energy. Thus, the H passivation would prevent the occurrence of edge reconstruction. Moreover, H passivation induces a metal-semiconductor transition in the zz and brc SiC NRs. Additionally, except for brc-H system which has non-magnetic semiconducting state, the zz-H, Crc-H, and Sirc-H systems have the magnetic state.

  14. Low energy pion detection by a silicon surface barrier telescope

    International Nuclear Information System (INIS)

    Sealock, R.M.; Caplan, H.S.; Leung, M.K.

    1978-01-01

    Four telescopes of three (2-ΔE, 1-E) silicon surface barrier detectors each, mounted in the focal plane of a magnetic spectrometer, have been used to detect positive pions in the energy range from 4.7-17.9 MeV and negative pions from 14.1-17.9 MeV. Positive pions from 4.7-12.7 MeV were stopped in the third detector while positive and negative pions from 14.1-17.9 MeV were detected in transmission. For energies greater than 7.4 MeV aluminum moderators were placed in front of the first detector to degrade the pion energy. Energy spectra show well resolved pion peaks with extremely low background. Double differential cross sections for the 12 C(e,π + ) 12 B,e' reaction have been measured. (Auth.)

  15. Planar UV excilamp excited by a surface barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Guivan, N N [Department of Quantum Electronics, Uzhgorod National University, Pidgirna 46, Uzhgorod 88000 (Ukraine); Janca, J [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); Brablec, A [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); Stahel, P [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); SlavIcek, P [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); Shimon, L L [Department of Quantum Electronics, Uzhgorod National University, Pidgirna 46, Uzhgorod 88000 (Ukraine)

    2005-09-07

    In this paper, the typical characteristics of a planar excilamp based on KrCl* and XeCl* exciplex molecules are presented. The excitation of the working mixture Kr/Xe/Cl{sub 2} is realized by means of the surface barrier discharge at pressures of 0.1-1 bar. The following properties are measured and discussed: spectra emitted by the plasma in the UV/VIS/NIR spectral range, intensity of emitted light versus total pressure in the discharge, the composition of the working mixture and the power of emitted light. The radiation power versus input electric power, and space distribution of the emitted light including basic electrical parameters of the discharge were also measured. It was shown that the characteristic power of UV radiation emitted in the spectral range 200-400 nm is about 6 mW cm{sup -2} while the efficiency could be about 8%.

  16. T Tank Farm Interim Surface Barrier Demonstration -- Vadose Zone Monitoring FY07 Report

    International Nuclear Information System (INIS)

    Zhang, Z. F.; Strickland, Christopher E.; Keller, Jason M.; Wittreich, Curtis D.; Sydnor, Harold A.

    2008-01-01

    CH2M HILL Hanford Group, Inc. is currently in the process of constructing a temporary surface barrier over a portion of the T Tank Farm as part of the T farm Interim Surface Barrier Demonstration Project. The surface barrier is designed to prevent the infiltration of precipitation into the contaminated soil zone created by the Tank T-106 leak and minimize movement of the contamination. As part of the demonstration effort, vadose zone moisture monitoring is being performed to assess the effectiveness of the barrier at reducing soil moisture. A solar-powered and remotely-controlled system was installed to continuously monitor soil water conditions in four instrument nests (i.e., A, B, C, and D) and the site meteorological condition. Each instrument nest was composed of a capacitance probe with multiple sensors, multiple heat-dissipation units, a neutron probe access tube and a datalogger. Nests A and B also contained a drain gauge each. The principle variables monitored for this purpose are soil-water content, soil-water pressure, and soil-water flux. In addition to these, soil temperature, precipitation, and air temperature are measured. Data from each of the dataloggers were transmitted remotely to the receiving computer. The neutron probe access tube was used to perform quarterly manual measurements of soil-water content using a neutron probe. This monitoring system was used to assess the soil water conditions in the soil outside and within the footprint of the surface barrier to be emplaced in the Hanford T Tank Farm. Data to date is baseline under the condition without the interim surface barrier in place. All the instruments except the two drain gauges were functional in FY07. The capacitance-probe measurements showed that the soil-moisture content at relatively shallow depths (e.g., 0.6 and 0.9 m) was increasing since October 2006 and reached the highest in early January 2007 followed by a slight decrease. Soil-moisture contents at the depths of 1.3 m and

  17. Competition of edge effects on the electronic properties and excitonic effects in short graphene nanoribbons

    International Nuclear Information System (INIS)

    Lu, Yan; Wei, Sheng; Jin, Jing; Wang, Li; Lu, Wengang

    2016-01-01

    We explore the electronic properties and exciton effects in short graphene nanoribbons (SGNRs), which have two armchair edges and two zigzag edges. Our results show that both of these two types of edges have profound effects on the electronic properties and exciton effects. Both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) states are alternatively changed between the bulk and the edge states as the lengths of the zigzag edges increase, due to the competition between the states of the two types of edges. The energy gaps, as a function of the lengths of the armchair edges, will then induce two kinds of trends. Furthermore, two kinds of exciton energies and exciton binding energies are found, which can be understood through the two kinds of HOMO and LUMO states in SGNRs. In addition, we find that the three triplet exciton states are not totally energy degenerate in SGNRs due to the spin-polarized states on the zigzag edges. (paper)

  18. Effects of suture position on left ventricular fluid mechanics under mitral valve edge-to-edge repair.

    Science.gov (United States)

    Du, Dongxing; Jiang, Song; Wang, Ze; Hu, Yingying; He, Zhaoming

    2014-01-01

    Mitral valve (MV) edge-to-edge repair (ETER) is a surgical procedure for the correction of mitral valve regurgitation by suturing the free edge of the leaflets. The leaflets are often sutured at three different positions: central, lateral and commissural portions. To study the effects of position of suture on left ventricular (LV) fluid mechanics under mitral valve ETER, a parametric model of MV-LV system during diastole was developed. The distribution and development of vortex and atrio-ventricular pressure under different suture position were investigated. Results show that the MV sutured at central and lateral in ETER creates two vortex rings around two jets, compared with single vortex ring around one jet of the MV sutured at commissure. Smaller total orifices lead to a higher pressure difference across the atrio-ventricular leaflets in diastole. The central suture generates smaller wall shear stresses than the lateral suture, while the commissural suture generated the minimum wall shear stresses in ETER.

  19. Diagnostic x-ray spectra measurements using a silicon surface barrier detector

    International Nuclear Information System (INIS)

    Pani, R.; Laitano, R.F.

    1987-01-01

    A silicon surface barrier detector having a low efficiency for x-ray is used to analyse diagnostic x-ray spectra. This characteristic is advantageous in overcoming experimental problems caused by high fluence rates typical of diagnostic x-ray beams. The pulse height distribution obtained with silicon surface barrier detectors is very different from the true photon spectra because of the presence of escaped Compton photons and the fact that detection efficiency falls abruptly when photon energy increases. A detailed analysis of the spurious effects involved in detection is made by a Monte Carlo method. A stripping procedure is described for implementation on a personal computer. The validity of this method is tested by comparison with experimental results obtained with a Ge detector. The spectra obtained with the Si detector are in fairly good agreement with the analogous spectra measured with a Ge detector. The advantages of using Si as opposed to Ge detectors in x-ray spectrometry are: its simplicity of use, its greater economy for use in routine diagnostic x-ray spectroscopy and the possibility that the stripping procedure can be implemented on a personal computer. (author)

  20. The development of surface barriers at the Hanford Site

    International Nuclear Information System (INIS)

    Wing, N.R.; Gee, G.W.

    1994-03-01

    Engineered barriers are being developed to isolate wastes disposed of near the earth's surface at the US Department of Energy's (DOE) Hanford Site near Richland, Washington. Much of the waste that would be disposed of by in-place stabilization currently is located in relatively shallow subsurface structures such as solid waste burial grounds, tanks, vaults, and cribs. Unless protected in some way, the wastes could be transported to the accessible environment via the following pathways: plant, animal, and human intrusion; water infiltration; erosion; and the exhalation of noxious gases. Permanent isolation surface barriers have been proposed to protect wastes disposed of ''in place'' from the transport pathways identified previously (Figure 1). The protective barrier consists of a variety of different materials (e.g., fine soil, sand, gravel, riprap, asphalt, etc.) placed in layers to form an above-grade mound directly over the waste zone. Surface markers are being considered for placement around the periphery of the waste sites to inform future generations of the nature and hazards of the buried wastes. In addition, throughout the protective barrier, subsurface markers could be placed to warn any inadvertent human intruders of the dangers of the buried wastes (Figure 2)

  1. Investigation of the characteristics of atmospheric pressure surface barrier discharges

    International Nuclear Information System (INIS)

    Zhang Rui; Zhan Rujuan; Wen Xiaohui; Wang Lei

    2003-01-01

    Experiments were performed on atmospheric pressure surface barrier discharges. Two types of panels were used. Both have pectinate high voltage electrodes on their upper surface, but the difference is that in type I, the grounded electrode consists of the same pectinate electrodes on the lower surface, whereas type II has an extended grounded plane electrode on the lower surface. The excitation temperature was determined from a Fermi-Dirac model and a temperature near 0.7 eV is obtained. The electron density was estimated from an electrical conductivity approach (Ohmic heating model) - an equivalent circuit model is proposed and the electron density is found to be of the order of 10 11 cm -3 . The electrical behaviour was studied, and it was found that the average power consumed in the discharge plasma increases with increasing strip width in the type I discharge, whereas it remains almost constant with increasing strip width in the type II discharge. The average discharge power remains almost constant with variation in the strip-to-strip distance. The type II discharge consumes much higher average discharge power than type I. We also find that panels with a larger height of high voltage electrodes can generate brighter and thicker discharge plasmas. The equivalent circuit model was used to interpret these phenomena

  2. Control of Eolian soil erosion from waste site surface barriers

    International Nuclear Information System (INIS)

    Ligotke, M.W.

    1994-11-01

    Physical models were tested in a wind tunnel to determine optimum surface-ravel admixtures for protecting silt-loam soil from erosion by, wind and saltating, sand stresses. The tests were performed to support the development of a natural-material surface barrier for and waste sites. Plans call for a 2-m deep silt-loam soil reservoir to retain infiltrating water from rainfall and snowmelt. The objective of the study was to develop a gravel admixture that would produce an erosion-resistant surface layer during, periods of extended dry climatic stress. Thus, tests were performed using simulated surfaces representing dry, unvegetated conditions present just after construction, after a wildfire, or during an extended drought. Surfaces were prepared using silt-loam soil mixed with various grades of sand and Travel. Wind-induced surface shear stresses were controlled over the test surfaces, as were saltating, sand mass flow rates and intensities. Tests were performed at wind speeds that approximated and exceeded local 100-year peak gust intensities. Surface armors produced by pea gravel admixtures were shown to provide the best protection from wind and saltating sand stresses. Compared with unprotected silt-loam surfaces, armored surfaces reduced erosion rates by more than 96%. Based in part on wind tunnel results, a pea gravel admixture of 15% will be added to the top 1 in of soil in a prototype barrier under construction in 1994. Field tests are planned at the prototype site to provide data for comparison with wind tunnel results

  3. Gamma detection: an unusual application for surface barrier detectors

    Energy Technology Data Exchange (ETDEWEB)

    Fichtenbaum de Iacub, S; Matatagui, E

    1983-02-01

    The silicon surface barrier detectors (SBD), may be ideal devices to be used in dose indicators for the monitoring of gamma radiations; the SBD working as a cavity sensor. The measurement consists in counting the number of pulses that exceeds a certain level of discrimination, this number being proportional to the absorbed dose. The spectral distribution of the pulses gives an idea of the existing photon field's energy. Characteristic spectra obtained with different gamma and X-ray sources are described and analyzed, and tests are carried out by using different sensitive volumes of the detector in order to determine significant parameters for a gamma-monitor system. The results from the measurements indicate: a) high sensitivity of the system with SBD (high density of material); b) low background: enviromental backgrounds are reliably registered (approx. 10 R/h); c) minimum detectable energies of the order of 60 keV; d) possibility to determine high exposure rates (approx. 100 R/h); e) for emitters of low Z, the result is approximately independent from the gamma energy. These results suggest the possibility of constructing fixed and portable systems, appropriate for gamma monitoring, which utilize SBD as sensors; these devices are adequate for working at enviroment temperatures, being compact, reliable, with low polarization voltages, and of relatively low cost.

  4. Gamma detection: an unusual application for surface barrier detectors

    International Nuclear Information System (INIS)

    Fichtenbaum de Iacub, Silvana; Matatagui, Emilio

    1983-01-01

    The silicon surface barrier detectors (SBD), may be ideal devices to be used in dose indicators for the monitoring of gamma radiations; the SBD working as a cavity sensor. The measurement consists in counting the number of pulses that exceeds a certain level of discrimination, this number being proportional to the absorbed dose. The spectral distribution of the pulses gives an idea of the existing photons field's energy. Characteristic spectra obtained with different gamma-and X ray sources are described and analyzed, and tests are carried out by using different sensitive volumes of the detector in order to determine significant parameters for a gamma-monitor system. The results from the measurements indicate: a) high sensitivity of the system with SBD (high density of material); b) low background: enviromental backgrounds are reliably registered (approx. 10μ R/h); c) minimum detectable energies of the order of 60 keV; d) possibility to determine high exposure rates (approx. 100 R/h); e) for emitters of low Z, the result is approximately independent from the gamma energy. These results suggest the possibility of constructing fixed and portable systems, appropriate for gamma monitoring, which utilize SBD as sensors; these devices are adequate for working at enviroment temperatures, being compact, reliable, with low polarization voltages, and of relatively low cost. (M.E.L.) [es

  5. Habitat edges have weak effects on duck nest survival at local spatial scales

    Science.gov (United States)

    Raquel, Amelia J; Ringelman, Kevin M.; Ackerman, Joshua T.; Eadie, John M.

    2015-01-01

    Edge effects on nesting success have been documented in breeding birds in a variety of contexts, but there is still uncertainty in how edge type and spatial scale determine the magnitude and detectability of edge effects. Habitat edges are often viewed as predator corridors that surround or penetrate core habitat and increase the risk of predation for nearby nests. We studied the effects of three different types of potential predator corridors (main perimeter roads, field boundaries, and ATV trails within fields) on waterfowl nest survival in California. We measured the distance from duck nests to the nearest edge of each type, and used distance as a covariate in a logistic exposure analysis of nest survival. We found only weak evidence for edge effects due to predation. The best supported model of nest survival included all three distance categories, and while all coefficient estimates were positive (indicating that survival increased with distance from edge), 85% coefficient confidence intervals approached or bounded zero indicating an overall weak effect of habitat edges on nest success. We suggest that given the configuration of edges at our site, there may be few areas far enough from hard edges to be considered ‘core’ habitat, making edge effects on nest survival particularly difficult to detect.

  6. Effect of Edge Roughness on Static Characteristics of Graphene Nanoribbon Field Effect Transistor

    Directory of Open Access Journals (Sweden)

    Yaser M. Banadaki

    2016-03-01

    Full Text Available In this paper, we present a physics-based analytical model of GNR FET, which allows for the evaluation of GNR FET performance including the effects of line-edge roughness as its practical specific non-ideality. The line-edge roughness is modeled in edge-enhanced band-to-band-tunneling and localization regimes, and then verified for various roughness amplitudes. Corresponding to these two regimes, the off-current is initially increased, then decreased; while, on the other hand, the on-current is continuously decreased by increasing the roughness amplitude.

  7. Effect of the edge type and strain on the structural, electronic and magnetic properties of the BNRs.

    Science.gov (United States)

    Bhattacharyya, Swastibrata; Kawazoe, Yoshiyuki; Singhl, Abhishek K

    2012-03-01

    We present the effect of edge structures on the edge energy and stress of BN nanoribbons. Ab initio density functional calculations show that the armchair edge is lower in energy than the zigzag edge by 0.43 eV/angstrom. Both types of the edges are under the compressive stress. The zigzag edges are mechanically more stable than the armchair edges. Based on the calculated edge energies, the equilibrium shape of the BN flakes are found to be regular hexagonal, and dominated by the armchair edges. The zigzag ribbons are found to be half-metallic, whereas the armchair ribbons are semiconducting.

  8. Nonlinear simulations of particle source effects on edge localized mode

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J.; Tang, C. J. [College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Chen, S. Y., E-mail: sychen531@163.com [College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Southwestern Institute of Physics, Chengdu 610041 (China); Wang, Z. H. [Southwestern Institute of Physics, Chengdu 610041 (China)

    2015-12-15

    The effects of particle source (PS) with different intensities and located positions on Edge Localized Mode (ELM) are systematically studied with BOUT++ code. The results show the ELM size strongly decreases with increasing the PS intensity once the PS is located in the middle or bottom of the pedestal. The effects of PS on ELM depend on the located position of PS. When it is located at the top of the pedestal, peeling-ballooning (P-B) modes can extract more free energy from the pressure gradient and grow up to be a large filament at the initial crash phase and the broadening of mode spectrum can be suppressed by PS, which leads to more energy loss. When it is located in the middle or bottom of the pedestal, the extraction of free energy by P-B modes can be suppressed, and a small filament is generated. During the turbulence transport phase, the broader mode spectrum suppresses the turbulence transport when PS is located in the middle, while the zonal flow plays an important role in damping the turbulence transport when PS is located at the bottom.

  9. Potential environmental effects of the leading edge hydrokinetic energy technology.

    Science.gov (United States)

    2017-05-01

    The Volpe Center evaluated potential environmental challenges and benefits of the ARPA-E funded research project, Marine Hydrokinetic Energy Harvesting Using Cyber-Physical Systems, led by Brown University. The Leading Edge research team develo...

  10. Longitudinal Proximity Effect Superconducting Transition-Edge Sensor

    Data.gov (United States)

    National Aeronautics and Space Administration — Superconducting Transition-Edge Sensors (TESs) hold the highest energy resolving power of any nondispersive spectrometer.   They are used for imaging spectroscopy...

  11. Finite size effects on the helical edge states on the Lieb lattice

    International Nuclear Information System (INIS)

    Chen Rui; Zhou Bin

    2016-01-01

    For a two-dimensional Lieb lattice, that is, a line-centered square lattice, the inclusion of the intrinsic spin–orbit (ISO) coupling opens a topologically nontrivial gap, and gives rise to the quantum spin Hall (QSH) effect characterized by two pairs of gapless helical edge states within the bulk gap. Generally, due to the finite size effect in QSH systems, the edge states on the two sides of a strip of finite width can couple together to open a gap in the spectrum. In this paper, we investigate the finite size effect of helical edge states on the Lieb lattice with ISO coupling under three different kinds of boundary conditions, i.e., the straight, bearded and asymmetry edges. The spectrum and wave function of edge modes are derived analytically for a tight-binding model on the Lieb lattice. For a strip Lieb lattice with two straight edges, the ISO coupling induces the Dirac-like bulk states to localize at the edges to become the helical edge states with the same Dirac-like spectrum. Moreover, it is found that in the case with two straight edges the gapless Dirac-like spectrum remains unchanged with decreasing the width of the strip Lieb lattice, and no gap is opened in the edge band. It is concluded that the finite size effect of QSH states is absent in the case with the straight edges. However, in the other two cases with the bearded and asymmetry edges, the energy gap induced by the finite size effect is still opened with decreasing the width of the strip. It is also proposed that the edge band dispersion can be controlled by applying an on-site potential energy on the outermost atoms. (paper)

  12. Roughness Effects on the Formation of a Leading Edge Vortex

    Science.gov (United States)

    Elliott, Cassidy; Lang, Amy; Wahidi, Redha; Wilroy, Jacob

    2016-11-01

    Microscopic scales cover the wings of Monarch butterflies, creating a patterned surface. This patterning is an important natural flow control mechanism that is thought to delay the growth of the leading edge vortex (LEV) produced by the flapping motion of a wing. The increased skin friction caused by the scales leads to a weaker LEV being shed into the butterfly's wake, lessening drag and increasing flight efficiency. To test this theory, a plate of random roughness was designed in SolidWorks and printed on the Objet 30 Pro 3D printer. A 2x3x5 cubic foot tow tank was used to test the rough plate at Reynold's numbers of 1500, 3000, and 6000 (velocities of 8, 16, and 32 mm/s) at an angle of attack of 45 degrees. Particle Image Velocimetry (PIV) captured images of the LEV generated by the plate when towed upwards through the particle-seeded flow. Codes written in MatLab were used to automatically track and determine the strength of the LEV. Circulation values for the randomly-rough plate were then compared to the same values generated in a previous experiment that used a smooth plate and a grooved plate to determine the effect of the patterning on vortex development. Funding provided by NSF REU site Grant EEC 1358991 and CBET 1628600.

  13. Effect of Internal and Edge Transport Barriers in ITER Simulations

    International Nuclear Information System (INIS)

    Pianroj, Y.; Onjun, T.; Suwanna, S.; Picha, R.; Poolyarat, N.

    2009-07-01

    Full text: Predictive simulations of ITER with the presence of both an edge transport barrier (ETB) and an internal transport barrier (ITB) are carried out using the BALDUR integrated predictive modeling code. In these simulations, the boundary is taken at the top of the pedestal, where the pedestal values are described using the theory-based pedestal models. These pedestal temperature models are based on three different pedestal width scalings: magnetic and flow shear stabilization (δ α ρ ζ 2 ), flow shear stabilization (δ α Root ρ Rq), and normalized poloidal pressure (δ α R Root βθ, ped). The pedestal width scalings are combined with a pedestal pressure gradient scaling based on ballooning mode limit to predict the pedestal temperature. A version of the semi-empirical Mixed Bohm/gyro Bohm (Mixed B/gB) core transport model that includes ITB effects is used to compute the evolution of plasma profiles and plasma performance, which defined by Fusion Q factor. The results from the cases excluding and including ITB are compared. The preliminary results show the Q value resulted from ITB-excluded simulation is less than the one with ITB included

  14. Fabrication and characterization of surface barrier detector from commercial silicon substrate

    International Nuclear Information System (INIS)

    Silva, Julio Batista Rodrigues

    2016-01-01

    In this work it was developed radiation detectors silicon surface barrier that were capable of detecting the presence of gamma radiation from a low energy of iodine-125 seeds used in brachytherapy treatments. >From commercial silicon substrates detectors were developed, one sequence left of chemical treatments to the surfaces of these substrates with the intention of minimizing the possible noise generated, validation of the samples obtained as diodes, ensuring detector characteristics and effective use as detector for Iodine-125 radioactive sources with energy of about 25 keV and Americium-251 with energy on the order of 59 keV. Finished performing the analysis of the obtained energy spectra and so it was possible to observe the ability of these detectors to measure the energy from these seeds. (author)

  15. Study of the round edge disk hole's effects on the frequency and wakefield in disc structure

    International Nuclear Information System (INIS)

    Wang Lanfa; Hou Mi; Zhang Chuang

    2001-01-01

    The effects of the round edge beam hole on the frequency and wake field are studied using variational method, which allows for rounded iris disk hole without any approximation in shape treatment. The frequencies and wake fields of accelerating mode and dipole mode are studied for different edge radius cases, including the flat edge shape that is often used to approximately represent the actual structure geometry. The edge hole shape has weak effect on the frequency, but strong effect on the wakefield. The study shows that the amounts of wake fields are not precise enough with the assumption of the flat edge beam hole as of round edge. The shape assumption brings loss factor 15% err for the most dangerous EH 16 mode

  16. Edge effects on moisture reduce wood decomposition rate in a temperate forest.

    Science.gov (United States)

    Crockatt, Martha E; Bebber, Daniel P

    2015-02-01

    Forests around the world are increasingly fragmented, and edge effects on forest microclimates have the potential to affect ecosystem functions such as carbon and nutrient cycling. Edges tend to be drier and warmer due to the effects of insolation, wind, and evapotranspiration and these gradients can penetrate hundreds of metres into the forest. Litter decomposition is a key component of the carbon cycle, which is largely controlled by saprotrophic fungi that respond to variation in temperature and moisture. However, the impact of forest fragmentation on litter decay is poorly understood. Here, we investigate edge effects on the decay of wood in a temperate forest using an experimental approach, whereby mass loss in wood blocks placed along 100 m transects from the forest edge to core was monitored over 2 years. Decomposition rate increased with distance from the edge, and was correlated with increasing humidity and moisture content of the decaying wood, such that the decay constant at 100 m was nearly twice that at the edge. Mean air temperature decreased slightly with distance from the edge. The variation in decay constant due to edge effects was larger than that expected from any reasonable estimates of climatic variation, based on a published regional model. We modelled the influence of edge effects on the decay constant at the landscape scale using functions for forest area within different distances from edge across the UK. We found that taking edge effects into account would decrease the decay rate by nearly one quarter, compared with estimates that assumed no edge effect. © 2014 John Wiley & Sons Ltd.

  17. Roughness Effects on the Formation of a Leading Edge Vortex

    Science.gov (United States)

    Elliott, Cassidy; Lang, Amy; Wahidi, Redha; Wilroy, Jacob

    2017-11-01

    Microscopic scales cover the wings of Monarch butterflies, creating a patterned surface that acts as a natural energy capture mechanism. This patterning is thought to delay the growth of the leading edge vortex (LEV) produced by the flapping motion of a wing. Increased skin friction caused by the scales leads to a weaker LEV being shed into the butterfly's wake, lessening drag and increasing flight efficiency. To test how this roughness effects LEV formation, a plate of random roughness was designed in SolidWorks and printed on the Objet 30 Pro 3D printer. A 2x3x5 cubic foot tow tank was used to test the rough plate at Reynold's numbers of 1500, 3000, and 6000 (velocities of 8, 16, and 32 mm/s) at an angle of attack of 45 degrees. Images were captured of the LEV generated when the plate was towed upwards through the particle-seeded flow. These images were used to determine the XY velocity of the particles using a technique called Digital Particle Image Velocimetry (DPIV). Codes written in MATLAB were used to track and measure the strength of the LEV. Circulation values for the randomly-rough plate were then compared to the same values generated in a previous experiment that used a smooth plate and a grooved plate to determine the effect of the patterning on vortex development. Funding for this research project was provided by the National Science Foundation under the Research Experience for Undergraduates (REU) program (REU Supplement CBET 1628600 under CBET 1335848).

  18. Edge effects and geometric constraints: a landscape-level empirical test.

    Science.gov (United States)

    Ribeiro, Suzy E; Prevedello, Jayme A; Delciellos, Ana Cláudia; Vieira, Marcus Vinícius

    2016-01-01

    Edge effects are pervasive in landscapes yet their causal mechanisms are still poorly understood. Traditionally, edge effects have been attributed to differences in habitat quality along the edge-interior gradient of habitat patches, under the assumption that no edge effects would occur if habitat quality was uniform. This assumption was questioned recently after the recognition that geometric constraints tend to reduce population abundances near the edges of habitat patches, the so-called geometric edge effect (GEE). Here, we present the first empirical, landscape-level evaluation of the importance of the GEE in shaping abundance patterns in fragmented landscapes. Using a data set on the distribution of small mammals across 18 forest fragments, we assessed whether the incorporation of the GEE into the analysis changes the interpretation of edge effects and the degree to which predictions based on the GEE match observed responses. Quantitative predictions were generated for each fragment using simulations that took into account home range, density and matrix use for each species. The incorporation of the GEE into the analysis changed substantially the interpretation of overall observed edge responses at the landscape scale. Observed abundances alone would lead to the conclusion that the small mammals as a group have no consistent preference for forest edges or interiors and that the black-eared opossum Didelphis aurita (a numerically dominant species in the community) has on average a preference for forest interiors. In contrast, incorporation of the GEE suggested that the small mammal community as a whole has a preference for forest edges, whereas D. aurita has no preference for forest edges or interiors. Unexplained variance in edge responses was reduced by the incorporation of GEE, but remained large, varying greatly on a fragment-by-fragment basis. This study demonstrates how to model and incorporate the GEE in analyses of edge effects and that this

  19. Effects of Edge on-Site Potential in a Honeycomb Topological Magnon Insulator

    Science.gov (United States)

    Pantaleón, Pierre A.; Xian, Yang

    2018-06-01

    While the deviation of the edge on-site potential from the bulk values in a magnonic topological honeycomb lattice leads to the formation of edge states in a bearded boundary, this is not the case for a zigzag termination, where no edge state is found. In a semi-infinite lattice, the intrinsic on-site interactions along the boundary sites generate an effective defect and this gives rise to Tamm-like edge states. If a nontrivial gap is induced, both Tamm-like and topologically protected edge states appear in the band structure. The effective defect can be strengthened by an external on-site potential, and the dispersion relation, velocity and magnon density of the edge states all become tunable.

  20. Evaluating the Performance of a Surface Barrier on Reducing Soil-Water Flow

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z. F.; Strickland, Christopher E.; Field, Jim G.; Parker, Danny L.; Clayton, Ray E.

    2012-08-31

    One of the most common effective techniques for contaminant remediation in the vadose zone is to use a surface barrier to reduce or eliminate soil-water flow to reduce the contaminant flux to the underlying groundwater. Confirming the reduction of the soil-water flux rate is challenging because of the difficulty of determining the very low soil-water flux beneath the barrier. We propose a hydraulic-conductivity factor, fK, as a conservative indicator for quantifying the reduction of soil-water flow. The factor can be calculated using the measured soil-water content or pressure but does not require the knowledge of the saturated hydraulic conductivity or the hydraulic gradient. The formulas were tested by comparing with changes in hydraulic conductivity, K, from a drainage experiment. The pressure-based formula was further applied to evaluate the performance of the interim surface barrier at T Tank Farm on Hanford Site. Three years after barrier emplacement, the hydraulic conductivity decreased by a factor between 3.8 and 13.0 at the 1-, 2- and 5-m depths. The difference between the conductivity-reduction factor and the flux-rate-reduction factor, fq, was quantified with a numerical simulation. With the calculated fK, the numerically determined fK/fq ratio, and the assumed pre-barrier soil-water flux rate of 100 mm yr-1, the estimated soil-water flux rate 3 years after barrier emplacement was no more than 8.5 mm yr-1 at or above the 5-m depth.

  1. Nonneutralized charge effects on tokamak edge magnetohydrodynamic stability

    International Nuclear Information System (INIS)

    Zheng, Linjin; Horton, W.; Miura, H.; Shi, T.H.; Wang, H.Q.

    2016-01-01

    Owing to the large ion orbits, excessive electrons can accumulate at tokamak edge. We find that the nonneutralized electrons at tokamak edge can contribute an electric compressive stress in the direction parallel to magnetic field by their mutual repulsive force. By extending the Chew–Goldburger–Low theory (Chew et al., 1956 [13]), it is shown that this newly recognized compressive stress can significantly change the plasma average magnetic well, so that a stabilization of magnetohydrodynamic modes in the pedestal can result. This linear stability regime helps to explain why in certain parameter regimes the tokamak high confinement can be rather quiet as observed experimentally.

  2. Truncation effects in connected arrays: Analytical models to describe the edge-induced wave phenomena

    NARCIS (Netherlands)

    Neto, A.; Cavallo, D.; Gerini, G.

    2011-01-01

    This paper presents a Green's function based procedure to assess edge effects in finite wideband connected arrays. Truncation effects are more severe in broadband arrays, since the inter-element mutual coupling facilitates the propagation of edge-born waves that can become dominant over large

  3. Edge Effects in a Composite Weakly Reinforced with Fibers of Rectangular Cross Section

    Science.gov (United States)

    Boichuk, V. Yu.

    2001-05-01

    This paper deal with the edge effect in a composite weakly reinforced with fibers of rectangular cross section and subjected to biaxial uniform loading. The edge effects due to the difference between Poisson's ratios of the composite components are studied. Numerical results are presented

  4. Edge effect of strained bilayer nanofilms for tunable multistability and actuation.

    Science.gov (United States)

    Hu, N; Han, X; Huang, S; Grover, H M; Yu, X; Zhang, L N; Trase, I; Zhang, J X J; Zhang, L; Dong, L X; Chen, Z

    2017-03-02

    We employed both theoretical and computational models supported by experiments to study the multistable behavior of an edge-effect driven Si/Cr micro-claw. Our study showed that individual micro-claws demonstrate either monostability or bistability as the magnitude of the edge effect is varied.

  5. EDGE EFFECT INFLUENCE TO REFLECTED IMPEDANCE OF EDDY-CURRENT PROBE

    Directory of Open Access Journals (Sweden)

    О. Закревський

    2012-04-01

    Full Text Available This work is dedicated to solve analytically the edge effect Eddy-Current Probe (ECP problem which helpto carry out mathematical research the edge effect influence to ECP precision and sensitivity ultrasonictransducer mechanical amplitude oscillation measurement mathematical research, pointed to cylindricalconductive objects radius control possibility with superimposed ECP.

  6. Edge effect in charged-particle analyzing magnets

    NARCIS (Netherlands)

    Braams, C.M.

    The manner in which local saturation of pole pieces with sharp edges affects the fall-off of the magnetic induction in the fringing-field region is discussed and measured. Local saturation appears to set in at a field strength well below that at which over-all saturation of the pole pieces becomes

  7. Edge effects on understory epiphytic ferns and epiphyllous bryophytes in moist afromontane forests of Ethiopia

    Directory of Open Access Journals (Sweden)

    Hylander Kristoffer

    2013-12-01

    Full Text Available Most studies on edge effects in tropical forests have been conducted in landscapes with low human population density and in situations where the edges have been left unused after logging of the adjacent area. Here we studied forest margins heavily used by local farmers in a forest/agriculture mosaic landscape in Ethiopia. We compared forest structure and plant species composition across 41 forest-agriculture ecotones from 200 m out into the agricultural area to 200 m into the forest. There are strong edge effects from the edge and into the forest on canopy cover and number of stumps and apparently these forest-agricultural edges are intensively used by humans. They are penetrated by paths, beehives are found in the trees, timber of various dimensions is harvested and there is sometimes substantial cover of perennial wild (or semi-wild crops such as coffee and spices. The number of understory epiphytic fern species as well as number of epiphyllous (i.e., growing on leaves bryophyte species was lower at 20 m than at 75 m from the edge. The number of fern species was higher in newly created edges and thereafter they declined, which indicates an extinction debt. This pattern was not seen for the epiphyllous bryophytes. It is likely that different human management activities are responsible for many of the found edge effects besides wind and sun effects from the edge. Tropical forest margins provide important resources for people in many landscapes. It is important to understand how such use affects the biota of the forests. This study shows that there are substantial edge effects, but that the edge effects do not seem to become worse over time for epiphyllous bryophytes and only slightly so for ferns.

  8. Modeling of edge effect in subaperture tool influence functions of computer controlled optical surfacing.

    Science.gov (United States)

    Wan, Songlin; Zhang, Xiangchao; He, Xiaoying; Xu, Min

    2016-12-20

    Computer controlled optical surfacing requires an accurate tool influence function (TIF) for reliable path planning and deterministic fabrication. Near the edge of the workpieces, the TIF has a nonlinear removal behavior, which will cause a severe edge-roll phenomenon. In the present paper, a new edge pressure model is developed based on the finite element analysis results. The model is represented as the product of a basic pressure function and a correcting function. The basic pressure distribution is calculated according to the surface shape of the polishing pad, and the correcting function is used to compensate the errors caused by the edge effect. Practical experimental results demonstrate that the new model can accurately predict the edge TIFs with different overhang ratios. The relative error of the new edge model can be reduced to 15%.

  9. Awareness of Central Luminance Edge is Crucial for the Craik-O'Brien-Cornsweet Effect.

    Science.gov (United States)

    Masuda, Ayako; Watanabe, Junji; Terao, Masahiko; Watanabe, Masataka; Yagi, Akihiro; Maruya, Kazushi

    2011-01-01

    The Craik-O'Brien-Cornsweet (COC) effect demonstrates that perceived lightness depends not only on the retinal input at corresponding visual areas but also on distal retinal inputs. In the COC effect, the central edge of an opposing pair of luminance gradients (COC edge) makes adjoining regions with identical luminance appear to be different. To investigate the underlying mechanisms of the effect, we examined whether the subjective awareness of the COC edge is necessary for the generation of the effect. We manipulated the visibility of the COC edge using visual backward masking and continuous flash suppression while monitoring subjective reports regarding online percepts and aftereffects of adaptation. Psychophysical results showed that the online percept of the COC effect nearly vanishes in conditions where the COC edge is rendered invisible. On the other hand, the results of adaptation experiments showed that the COC edge is still processed at the early stage even under the perceptual suppression. These results suggest that processing of the COC edge at the early stage is not sufficient for generating the COC effect, and that subjective awareness of the COC edge is necessary.

  10. Inverted edge effects on carbon stocks in human-dominated landscapes

    Science.gov (United States)

    Romitelli, I.; Keller, M.; Vieira, S. A.; Metzger, J. P.; Reverberi Tambosi, L.

    2017-12-01

    Although the importance of tropical forests to regulate greenhouse gases is well documented, little is known about what factors affect the ability of these forests to store carbon in human-dominated landscapes. Among those factors, the landscape structure, particularly the amount of forest cover, the type of matrix and edge effects, can have important roles. We tested how carbon stock is influenced by a combination of factors of landscape composition (pasture and forest cover), landscape configuration (edge effect) and relief factors (slope, elevation and aspect). To test those relationships, we performed a robust carbon stock estimation with inventory and LiDAR data in human-dominated landscapes from the Brazilian Atlantic forest region. The study area showed carbon stock mean 45.49 ± 9.34 Mg ha-1. The interaction between forest cover, edge effect and slope was the best combination explanatory of carbon stock. We observed an inverted edge effect pattern where carbon stock is higher close to the edges of the studied secondary forests. This inverted edge effect observed contradicts the usual pattern reported in the literature for mature forests. We suppose this pattern is related with a positive effect that edge conditions can have stimulating forest regeneration, but the underlying processes to explain the observed pattern should still be tested. Those results suggest that Carbon stocks in human-dominated and fragmented landscapes can be highly affected by the landscape structure, and particularly that edges conditions can favor carbon sequestration in regenerating tropical forests.

  11. Edge effects in phase-shifting masks for 0.25-µm lithography

    Science.gov (United States)

    Wong, Alfred K. K.; Neureuther, Andrew R.

    1993-03-01

    The impact on image quality of scattering from phase-shifter edges and of interactions between phase-shifter and chrome edges is assessed using rigorous electromagnetic simulation. Effects of edge taper in phase-shift masks, spacing between phase-shifter and chrome edges, small outrigger features with a trench phase-shifter, and of the repair of phase defects by etching to 360 degree(s) are considered. Near field distributions and diffraction efficiencies are examined and images are compared with more approximate results from the commonly used Hopkins' theory of imaging.

  12. Understanding and tuning the quantum-confinement effect and edge magnetism in zigzag graphene nanoribbon.

    Science.gov (United States)

    Huang, Liang Feng; Zhang, Guo Ren; Zheng, Xiao Hong; Gong, Peng Lai; Cao, Teng Fei; Zeng, Zhi

    2013-02-06

    The electronic structure of zigzag graphene nanoribbon (ZGNR) is studied using density functional theory. The mechanisms underlying the quantum-confinement effect and edge magnetism in ZGNR are systematically investigated by combining the simulated results and some useful analytic models. The quantum-confinement effect and the inter-edge superexchange interaction can be tuned by varying the ribbon width, and the spin polarization and direct exchange splitting of the edge states can be tuned by varying their electronic occupations. The two edges of ZGNR can be equally or unequally tuned by charge doping or Li adsorption, respectively. The Li adatom has a site-selective adsorption on ZGNR, and it is a nondestructive and memorable approach to effectively modify the edge states in ZGNR. These systematic understanding and effective tuning of ZGNR electronics presented in this work are helpful for further investigation and application of ZGNR and other magnetic graphene systems.

  13. Crop type influences edge effects on the reproduction of songbirds in sagebrush habitat near agriculture

    Directory of Open Access Journals (Sweden)

    Elly C. Knight

    2014-06-01

    Full Text Available Extensive fragmentation of the sagebrush shrubsteppe of western North America could be contributing to observed population declines of songbirds in sagebrush habitat. We examined whether habitat fragmentation impacts the reproduction of songbirds in sagebrush edge habitat near agriculture, and if potential impacts vary depending on the adjacent crop type. Specifically, we evaluated whether nest abundance and nest survival varied between orchard edge habitat, vineyard edge habitat, and interior habitat. We then examined whether the local nest predator community and vegetation could explain the differences detected. We detected fewer nests in edge than interior habitat. Nest abundance per songbird was also lower in edge than interior habitat, although only adjacent to vineyards. Nest predation was more frequent in orchard edge habitat than vineyard edge or interior habitat. Predators identified with nest cameras were primarily snakes, however, reduced nest survival in orchard edge habitat was not explained by differences in the abundance of snakes or any other predator species identified. Information theoretic analysis of daily survival rates showed that greater study plot shrub cover and lower grass height at nests were partially responsible for the lower rate of predation-specific daily nest survival rate (PDSR observed in orchard edge habitat, but additional factors are likely important. Results of this study suggest that different crop types have different edge effects on songbirds nesting in sagebrush shrubsteppe, and that these reproductive edge effects may contribute to observed declines of these species. Habitat managers should avoid the creation of new orchard-sagebrush habitat edges to avoid further impacts on already declining songbird populations.

  14. Edge modes in the fractional quantum Hall effect without extra edge fermions

    Science.gov (United States)

    Lima, G. L. S.; Dias, S. A.

    2011-05-01

    We show that the Chern-Simons-Landau-Ginsburg theory that describes the quantum Hall effect on a bounded sample is anomaly free and thus does not require the addition of extra chiral fermions on the boundary to restore local gauge invariance.

  15. Effects of edge reconstruction on the common groups terminated zigzag phosphorene nanoribbon

    International Nuclear Information System (INIS)

    Xiao, Huaping; Guo, Sumei; Zhang, Chunxiao; He, Chaoyu; Zhong, Jianxin

    2017-01-01

    Edge configuration plays an important role in the electronic properties of nano-structures. In this work, we perform first-principles calculations to study the effects of the cooperation between neighbor groups on the edge configuration and the electronic properties of zigzag-PNRs (ZPNRs) terminated by common groups H, F, O, S and OH. We find that the cooperation has little effect on the H(F)-terminated ZPNRs, but gives rise to an edge reconstruction for the O(S)-terminated ZPNRs. The edge reconstruction derives from the repulsion between neighbor O atoms and the distortion of the P skeleton induced by the p state coupling among the edge, second edge and third edge P atoms. In comparison to the H-terminated ZPNRs, O-terminated ZPNRs are also a semiconductor and enlarge the band gap, but bring about an extra transport channel for the charge transport at the edge and decreases the effective mass of the electron and hole. OH-terminated ZPNRs also undergo a doubling of the unit cell (UC) along the periodic direction because of the different directions of the neighbor O–H bonds. In comparison with the H-terminated ZPNRs, OH-terminated ZPNRs show a similar band gap and electronic effective mass, but increase the effective mass of the hole. (paper)

  16. Surface barrier and bulk pinning in MgB$_2$ superconductor

    OpenAIRE

    Pissas, M.; Moraitakis, E.; Stamopoulos, D.; Papavassiliou, G.; Psycharis, V.; Koutandos, S.

    2001-01-01

    We present a modified method of preparation of the new superconductor MgB$_2$. The polycrystalline samples were characterized using x-ray and magnetic measurements. The surface barriers control the isothermal magnetization loops in powder samples. In bulk as prepared samples we always observed symmetric magnetization loops indicative of the presence of a bulk pinning mechanism. Magnetic relaxation measurements in the bulk sample reveal a crossover of surface barrier to bulk pinning.

  17. On the conductance sum rule for the hierarchical edge states of the fractional quantum hall effect

    International Nuclear Information System (INIS)

    Ma Zhongshui; Chen Yixin; Su Zhaobin.

    1993-09-01

    The conductance sum rule for the hierarchical edge channel currents of a Fractional Quantum Hall Effect state is derived analytically within the Haldane-Halperin hierarchy scheme. We provide also an intuitive interpretation for the hierarchical drift velocities of the edge excitations. (author). 12 refs

  18. Piecing together the fragments: Elucidating edge effects on forest carbon dynamics

    Science.gov (United States)

    Hutyra, L.; Smith, I. A.; Reinmann, A.; Marrs, J.; Thompson, J.

    2017-12-01

    Forest fragmentation is pervasive throughout the world's forests, impacting growing conditions and carbon dynamics through edge effects that produce gradients in microclimate, biogeochemistry, and stand structure. Despite the majority of the world's forests being biome, but current forest carbon accounting methods and ecosystem models largely do not include edge effects, highlighting an important gap in our understanding of the terrestrial carbon cycle. Characterizing the role of forest fragmentation in regional and global biogeochemical cycles necessitates advancing our understanding of how shifts in microenvironment at the forest edge interact with local prevailing drivers of global change and limitations to microbial activity and forest growth. This study synthesizes the literature related to edge effects and the carbon cycle, considering how fragmentation affects the growing conditions of the world's remaining forests based on risks and opportunities for forests near the edge.

  19. Edge geometry effects on resonance response of electroplated cylindrical Ni/PZT/Ni magnetoelectric composites

    Science.gov (United States)

    Yakubov, Vladislav; Xu, Lirong; Volinsky, Alex A.; Qiao, Lijie; Pan, De'an

    2017-08-01

    Trilayer Ni/PZT/Ni cylindrical magnetoelectric (ME) composites were prepared by electrodeposition, a process, which creates sub-millimeter raised edges due to current concentration near sharp points. The ME response in both axial and vertical modes was measured with the edges, with only outer edges removed, and with both outer and inner edges removed. The ME voltage coefficient improved at resonance by 40% and 147% without the edges in the vertical and axial modes, respectively. The observed improvements in three different samples were only present at the ME resonance and no changes were detected outside of the ME resonance. Mechanical quality factor at resonance also improved with no effect on the resonant frequency. Experimentally demonstrated minor geometry changes resulted in substantial ME improvement at resonant frequency. This study demonstrates device performance optimization. The observed effects have been attributed to improved vibrations in terms of decreased damping coefficient and enhanced vibration amplitude at resonance.

  20. Edge geometry effects on resonance response of electroplated cylindrical Ni/PZT/Ni magnetoelectric composites

    Directory of Open Access Journals (Sweden)

    Vladislav Yakubov

    2017-08-01

    Full Text Available Trilayer Ni/PZT/Ni cylindrical magnetoelectric (ME composites were prepared by electrodeposition, a process, which creates sub-millimeter raised edges due to current concentration near sharp points. The ME response in both axial and vertical modes was measured with the edges, with only outer edges removed, and with both outer and inner edges removed. The ME voltage coefficient improved at resonance by 40% and 147% without the edges in the vertical and axial modes, respectively. The observed improvements in three different samples were only present at the ME resonance and no changes were detected outside of the ME resonance. Mechanical quality factor at resonance also improved with no effect on the resonant frequency. Experimentally demonstrated minor geometry changes resulted in substantial ME improvement at resonant frequency. This study demonstrates device performance optimization. The observed effects have been attributed to improved vibrations in terms of decreased damping coefficient and enhanced vibration amplitude at resonance.

  1. Effect of the Curved Fin Top Edge on the Electrical Characteristics of FinFETs.

    Science.gov (United States)

    Ahn, Joonsung; Kim, Tae Whan

    2018-03-01

    The effect of the curved fin top edge on the electrical characteristics of FinFETs was investigated. The curvature radius of the fin top edge for the FinFETs was changed from 0 to 5 nm in order to determine the optimum condition of the electrical characteristics for the devices. The on-current level of the FinFETs with a curvature radius of 5 nm of fin top edge was 24.45% larger than that of the FinFETs with a cuboid fin. The electron current density and the electron mobility of the fin top edge for the FinFETs were larger than those for the FinFETs with a cuboid fin. The electrical characteristics of the FinFETs with a curvature radius of 5 nm for the fin top edge showed the best performance due to the largest expansion of the effective channel region.

  2. Unexpected Nonlinear Effects in Superconducting Transition-Edge Sensors

    Science.gov (United States)

    Sadleir, John

    2016-01-01

    When a normal metal transitions into the superconducting state the DC resistance drops from a finite value to zero over some finite transition width in temperature, current, and magnetic field. Superconducting transition-edge sensors (TESs) operate within this transition region and uses resistive changes to measure deposited thermal energy. This resistive transition is not perfectly smooth and a wide range of TES designs and materials show sub-structure in the resistive transition (as seen in smooth nonmonotonic behavior, jump discontinuities, and hysteresis in the devices current-voltage relation and derivatives of the resistance with respect to temperature, bias current, and magnetic field). TES technology has advanced to the point where for many applications this structure is the limiting factor in performance and optimization consists of finding operating points away from these structures. For example, operating at or near this structure can lead to nonlinearity in the detectors response and gain scale, limit the spectral range of the detector by limiting the usable resistive range, and degrade energy resolution. The origin of much of this substructure is unknown. This presentation investigates a number of possible sources in turn. First we model the TES as a superconducting weak-link and solve for the characteristic differential equations current and voltage time dependence. We find:(1) measured DC biased current-voltage relationship is the time-average of a much higher frequency limit cycle solution.(2) We calculate the fundamental frequency and estimate the power radiated from the TES treating the bias leads as an antennae.(3) The solution for a set of circuit parameters becomes multivalued leading to current transitions between levels.(4)The circuit parameters can change the measure resistance and mask the true critical current. As a consequence the TES resistance surface is not just a function of temperature, current, and magnetic field but is also a

  3. Valley-filtered edge states and quantum valley Hall effect in gated bilayer graphene.

    Science.gov (United States)

    Zhang, Xu-Long; Xu, Lei; Zhang, Jun

    2017-05-10

    Electron edge states in gated bilayer graphene in the quantum valley Hall (QVH) effect regime can carry both charge and valley currents. We show that an interlayer potential splits the zero-energy level and opens a bulk gap, yielding counter-propagating edge modes with different valleys. A rich variety of valley current states can be obtained by tuning the applied boundary potential and lead to the QVH effect, as well as to the unbalanced QVH effect. A method to individually manipulate the edge states by the boundary potentials is proposed.

  4. EFFECTS OF EDGE COVERING ON TENSILE STRENGTH OF MDF

    Directory of Open Access Journals (Sweden)

    Yalçın ÖRS

    1999-03-01

    Full Text Available Dowels, 6, 8 and 10 mm ? diameters were bonded with PVAc adhesive on Medium Density Fiberboard (MDF. Edges were covered with 5, 8 and 12 mm beech wood materials, drilled 25 mm depth. Tensile strength measurments were made on the samples. The highest tensile strength value was given as 6 mm ? dowel and MDF covered with 8 mm thickness beech wood material (2.294 N/mm2, the lowest value was obtained with 10 mm ? dowel and with unprocessed MDF (1.314 N/mm2.

  5. Leading edge effect in laminar boundary layer excitation by sound

    International Nuclear Information System (INIS)

    Leehey, P.; Shapiro, P.

    1980-01-01

    Essentially plane pure tone sound waves were directed downstream over a heavily damped smooth flat plate installed in a low turbulence (0.04%) subsonic wind tunnel. Laminar boundary layer disturbance growth rates were measured with and without sound excitation and compared with numerical results from spatial stability theory. The data indicate that the sound field and Tollmien-Schlichting (T-S) waves coexist with comparable amplitudes when the latter are damped; moreover, the response is linear. Higher early growth rates occur for excitation by sound than by stream turbulence. Theoretical considerations indicate that the boundary layer is receptive to sound excitation primarily at the test plate leading edge. (orig.)

  6. Flux surface shaping effects on tokamak edge turbulence and flows

    International Nuclear Information System (INIS)

    Kendl, A.; Scott, B.D.

    2004-01-01

    The influence of shaping of magnetic flux surfaces in tokamaks on gyro-fluid edge turbulence is studied numerically. Magnetic field shaping in tokamaks is mainly due to elongation, triangularity, shift and the presence of a divertor X-point. A series of tokamak configurations with varying elongation 1 ≤ κ ≥ 2 and triangularity 0 ≤ δ ≤ 0.4, and an actual ASDEX Upgrade divertor configuration are obtained with the equilibrium code HELENA and implemented into the gyro-fluid turbulence code GEM. The study finds minimal impact on the zonal flow physics itself, but strong impact on the turbulence and transport. (authors)

  7. Flux surface shaping effects on tokamak edge turbulence and flows

    Energy Technology Data Exchange (ETDEWEB)

    Kendl, A. [Innsbruck Univ., Institut fuer Theoretische Physik, Association EURATOM (Austria); Scott, B.D. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Garching bei Muenchen (Germany)

    2004-07-01

    The influence of shaping of magnetic flux surfaces in tokamaks on gyro-fluid edge turbulence is studied numerically. Magnetic field shaping in tokamaks is mainly due to elongation, triangularity, shift and the presence of a divertor X-point. A series of tokamak configurations with varying elongation 1 {<=} {kappa} {>=} 2 and triangularity 0 {<=} {delta} {<=} 0.4, and an actual ASDEX Upgrade divertor configuration are obtained with the equilibrium code HELENA and implemented into the gyro-fluid turbulence code GEM. The study finds minimal impact on the zonal flow physics itself, but strong impact on the turbulence and transport. (authors)

  8. Diversity of galling insects in Styrax pohlii (Styracaceae): edge effect and use as bioindicators.

    Science.gov (United States)

    de Araújol, Walter Santos; Julião, Genimar Rebouças; Ribeiro, Bárbara Araújo; Silva, Isadora Portes Abraham; dos Santos, Benedito Baptista

    2011-12-01

    Impacts of forest fragmentation and edge effect on plant-herbivores interactions are relatively unknown, and the relationships between galling insects and their host plants are very susceptible to environmental variations. The goal of our study was to test the edge effect hypothesis for galling insects associated with Styrax pohlii (Styracaceae) host plant. Samplings were conducted at a fragment of semi-deciduous forest in Goiânia, Goiás, Brazil. Thirty host plant individuals (15 at fragment edge and 15 in its interior) were sampled in July of 2007; in each plant, 10 apical branches were collected at the top, middle and bottom crown levels. Our results supported the prediction of greater richness of gall morphotypes in the edge habitat compared with remnant interior. In a similar way, gall abundance and frequency of attacked leaves were also greater in the fragment edge. These findings consequently suggest a positive response of galling insect diversity to edge effect; in the Saint-Hilaire forest, this effect probably operates through the changes in microclimatic conditions of edge habitats, which results in an increased hygrothermal stress, a determinant factor to distribution patterns of galling insects. We also concluded that these organisms could be employed as biological indicators (i) because of their host-specificity, (ii) they are sensitive to changes in plant quality, and (iii) present dissimilar and specific responses to local variation in habitat conditions.

  9. Graphene nanoribbons on gold: understanding superlubricity and edge effects

    Science.gov (United States)

    Gigli, L.; Manini, N.; Benassi, A.; Tosatti, E.; Vanossi, A.; Guerra, R.

    2017-12-01

    We address the atomistic nature of the longitudinal static friction against sliding of graphene nanoribbons (GNRs) deposited on gold, a system whose structural and mechanical properties have been recently the subject of intense experimental investigation. By means of numerical simulations and modeling we show that the GNR interior is structurally lubric (‘superlubric’) so that the static friction is dominated by the front/tail regions of the GNR, where the residual uncompensated lateral forces arising from the interaction with the underneath gold surface opposes the free sliding. As a result of this edge pinning the static friction does not grow with the GNR length, but oscillates around a fairly constant mean value. These friction oscillations are explained in terms of the GNR-Au(111) lattice mismatch: at certain GNR lengths close to an integer number of the beat (or moiré) length there is good force compensation and superlubric sliding; whereas close to half odd-integer periods there is significant pinning of the edge with larger friction. These results make qualitative contact with recent state-of-the-art atomic force microscopy experiment, as well as with the sliding of other different incommensurate systems.

  10. Edge effects in vertically-oriented graphene based electric double-layer capacitors

    Science.gov (United States)

    Yang, Huachao; Yang, Jinyuan; Bo, Zheng; Zhang, Shuo; Yan, Jianhua; Cen, Kefa

    2016-08-01

    Vertically-oriented graphenes (VGs) have been demonstrated as a promising active material for electric double-layer capacitors (EDLCs), partially due to their edge-enriched structure. In this work, the 'edge effects', i.e., edges as the promoters of high capacitance, in VG based EDLCs are investigated with experimental research and numerical simulations. VGs with diverse heights (i.e., edge-to-basal ratios) and edge densities are prepared with varying the plasma-enabled growth time and employing different plasma sources. Electrochemical measurements show that the edges play a predominant role on the charge storage behavior of VGs. A simulation is further conducted to unveil the roles of the edges on the separation and adsorption of ions within VG channels. The initial charge distribution of a VG plane is obtained with density functional theory (DFT) calculations, which is subsequently applied to a molecular dynamics (MD) simulation system to gain the insights into the microscope EDLC structures. Compared with the basal planes, the edges present higher initial charge density (by 4.2 times), higher ion packing density (by 2.6 times), closer ion packing location (by 0.8 Å), and larger ion separation degree (by 14%). The as-obtained findings will be instructive in designing the morphology and structure of VGs for enhanced capacitive performances.

  11. Edge effects on N2O, NO and CH4 fluxes in two temperate forests.

    Science.gov (United States)

    Remy, Elyn; Gasche, Rainer; Kiese, Ralf; Wuyts, Karen; Verheyen, Kris; Boeckx, Pascal

    2017-01-01

    Forest ecosystems may act as sinks or sources of nitrogen (N) and carbon (C) compounds, such as the climate relevant trace gases nitrous oxide (N 2 O), nitric oxide (NO) and methane (CH 4 ). Forest edges, which catch more atmospheric deposition, have become important features in European landscapes and elsewhere. Here, we implemented a fully automated measuring system, comprising static and dynamic measuring chambers determining N 2 O, NO and CH 4 fluxes along an edge-to-interior transect in an oak (Q. robur) and a pine (P. nigra) forest in northern Belgium. Each forest was monitored during a 2-week measurement campaign with continuous measurements every 2h. NO emissions were 9-fold higher than N 2 O emissions. The fluxes of NO and CH 4 differed between forest edge and interior, but not for N 2 O. This edge effect was more pronounced in the oak than in the pine forest. In the oak forest, edges emitted less NO (on average 60%) and took up more CH 4 (on average 177%). This suggests that landscape structure can play a role in the atmospheric budgets of these climate relevant trace gases. Soil moisture variation between forest edge and interior was a key variable explaining the magnitude of NO and CH 4 fluxes in our measurement campaign. To better understand the environmental impact of N and C trace gas fluxes from forest edges, additional and long-term measurements in other forest edges are required. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Role of edge effect on small mammal populations in a forest fragment

    International Nuclear Information System (INIS)

    Wike, L.D.

    2000-01-01

    In many cases, edge effect may determine the distribution and densities of small mammal populations. In 1995 and 1998, a mark and recapture study was conducted at the Savannah River Site (SRS), Aiken, SC, to evaluate the role of forest edge habitat. The area studied was an abandoned home site that had been recently isolated by a timber harvest. Harvest activities left a distinct edge of old field and planted pine contrasting with a relatively xeric, mixed hardwood stand. Trapping was conducted for 17 days in 1995 and 14 days in 1998. Three 30 m by 150 m grids were placed in the clear-cut, edge, and hardwood interior habitats. For both years the principal species captured were Peromyscus gossypinus, P. polionotus, and Neotoma floridana. The edge habitat accounted for approximately 55 percent of all captures and nearly four times as many recaptures as the interior and clear-cut habitats. In 1998, greater numbers of N. floridana were trapped than in 1995. The results indicate that the use of edge habitat can be pronounced even within simple communities. Stewards of managed or restored habitats need to carefully consider the role of edge in these systems. In managed areas such as waste sites, movement of material within the food chain could be reduced by minimizing edge habitat around the points of contamination

  13. Effect of readout direction in the edge profile on the modulation transfer function of computed radiographic systems by use of the edge method.

    Science.gov (United States)

    Tanaka, Nobukazu; Morishita, Junji; Tsuda, Norisato; Ohki, Masafumi

    2013-07-01

    We investigated the effect of the readout direction of the edge profile obtained by the edge method on the presampled modulation transfer function (MTF) in various computed radiographic (CR) systems. There were no differences in the MTFs derived from two edge profiles in the sub-scanning direction of four CR systems used in this study. On the other hand, the MTFs measured at a readout direction from the low (edge) to the high (direct exposure) exposure region were higher than those measured at a readout direction from the high to the low exposure region in the laser-beam scanning direction for three of the four CR systems. Although this phenomenon depends on the CR system, it is important to understand and indicate both MTFs at the two edge profiles in the laser-beam scanning direction for accurate assessment of the resolution property.

  14. Effect of finite edge radius on ductile fracture ahead of the cutting tool edge in micro-cutting of Al2024-T3

    International Nuclear Information System (INIS)

    Subbiah, Sathyan; Melkote, Shreyes N.

    2008-01-01

    Evidence of ductile fracture leading to material separation has been reported recently in ductile metal cutting [S. Subbiah, S.N. Melkote, ASME J. Manuf. Sci. Eng. 28(3) (2006)]. This paper investigates the effect of finite edge radius on such ductile fracture. The basic question of whether such ductile fracture occurs in the presence of a finite edge radius is explored by performing a series of experiments with inserts of different edge radii at various uncut chip thickness values ranging from 15 to 105 μm. Chip-roots are obtained in these experiments using a quick-stop device and examined in a scanning electron microscope. Clear evidence of material separation is seen at the interface zone between the chip and machined surface even when the edge radius is large compared to the uncut chip thickness. Failure is seen to occur at the upper, middle, and/or the lower edges of the interface zone. Based on these observations, a hypothesis is presented for the events leading to the occurrence of this failure when cutting with an edge radius tool. Finite element simulations are performed to study the nature of stress state ahead of the tool edge with and without edge radius. Hydrostatic stress is seen to be tensile in front of the tool and hence favors the occurrence of ductile fracture leading to material separation. The stress components are, however lower than those seen with a sharp tool

  15. Edge, height and visibility effects on nest predation by birds and mammals in the Brazilian cerrado

    Science.gov (United States)

    Dodonov, Pavel; Paneczko, Ingrid Toledo; Telles, Marina

    2017-08-01

    Edge influence is one of the main impacts in fragmented landscapes; yet, most of studies on edge influence have focused on high-contrast edges, and the impacts of low-contrast edges and narrow linear openings are less understood. Edge influence often affects bird nest predation, but these effects are not ubiquitous and may depend on characteristics such as nest height and visibility. We performed an experiment on nest predation in a migratory passerine, Elaenia chiriquensis (Lesser Elaenia; Passeriformes: Tyrannidae), in a savanna vegetation of the Brazilian Cerrado biome in South-Eastern Brazil. We used 89 real E. chiriquensis nests, collected during previous reproductive seasons, with two plasticine eggs in each, and randomly distributed them at two locations (edge - up to 20 m from a firebreak edge and interior - approx. 150-350 m from the edge) and two heights (low - 60-175 cm and high - 190-315 cm above ground). We also measured leaf and branch density around each nest. We performed this study on two 15-days campaigns, checking the nests every 2-3 days and removing those with predation marks. We sorted the predation marks into those made by birds, mammals, or unidentified predators, and used generalized linear models to assess the effects of location, height and leaf density on survival time and predator type. Only four nests had not been predated during the experiment; 55 nests were predated by birds, 7 by mammals, and 23 by unidentified predators. Low nests in the interior tended to have larger survival times whereas high nests at the edge tended to be more predated by birds and less predated by mammals. Thus, even a low-contrast (firebreak) edge may significantly increase nest predation, which is also affected by the nest's height, mainly due to predation by birds. These effects may be due to predator movement along the edge as well as to edge-related changes in vegetation structure. We suggest that higher-contrast edges which may also be used as movement

  16. Effects of edge magnetism on the Kohn anomalies of zigzag graphene nanoribbons

    International Nuclear Information System (INIS)

    Culchac, F J; Capaz, Rodrigo B

    2016-01-01

    The effects of edge magnetism on the Kohn anomaly (KA) of the G-band phonons of zigzag graphene nanoribbons (ZGNRs) are studied using a combination of the tight-binding and mean-field Hubbard models. We show that the opening of an energy gap, induced by magnetic ordering, significantly changes the KA effects, particularly for narrow ribbons in which the gap is larger than the phonon energy. Therefore, the G-band phonon frequency and lifetime are altered for a magnetically-ordered edge state with respect to an unpolarized edge state. The effects of temperature, ZGNR width, doping and transverse electric fields are systematically investigated. We propose using this effect to probe the magnetic order of edge states in graphene nanoribbons using Raman spectroscopy. (paper)

  17. An effective method for smoothing the staggered dose distribution of multi-leaf collimator field edge

    International Nuclear Information System (INIS)

    Hwang, I.-M.; Lin, S.-Y.; Lee, M.-S.; Wang, C.-J.; Chuang, K.-S.; Ding, H.-J.

    2002-01-01

    Purpose: To smooth the staggered dose distribution that occurs in stepped leaves defined by a multi-leaf collimator (MLC). Materials and methods: The MLC Shaper program controlled the stepped leaves, which were shifted in a traveling range, the pattern of shift was from the position of out-bound to in-bound with a one-segment (cross-bound), three-segment, and five-segment shifts. Film was placed at a depth of 1.5 cm and irradiated with the same irradiation dose used for the cerrobend block experiment. Four field edges with the MLC defining at 15 deg., 30 deg., 45 deg., 60 deg. angels relative to the jaw edge were performed, respectively, in this study. For the field edge defined by the multi-segment technique, the amplitude of the isodose lines for 50% isodose line and both the 80% and 20% isodose lines were measured. The effective penumbra widths with 90-10% and 80-20% distances for different irradiations were determined at four field edges with the MLC defining at 15 deg., 30 deg., 45 deg., 60 deg. angels relative to the jaw edge. Results: Use of the five-segment technique for multi-leaf collimation at the 60 deg. angle field edge smoothes each isodose line into an effectively straight line, similar to the pattern achieved using a cerrobend block. The separation of these lines is also important. The 80-20% effective penumbra width with five-segment techniques (8.23 mm) at 60 deg. angle relative to the jaw edge is little wider (1.9 times) than the penumbra of cerrobend block field edge (4.23 mm). We also found that the 90-10% effective penumbra width with five-segment techniques (12.68 mm) at 60 deg. angle relative to the jaw edge is little wider (1.28 times) than the penumbra of cerrobend block field edge (9.89 mm). Conclusion: The multi-segment technique is effective in smoothing the MLC staggered field edge. The effective penumbra width with more segment techniques at larger degree angles relative to the field edge is little wider than the penumbra for a

  18. Experimental Study of Electronic Quantum Interference, Photonic Crystal Cavity, Photonic Band Edge Effects for Optical Amplification

    Science.gov (United States)

    2016-01-26

    AFRL-RV-PS- AFRL-RV-PS- TR-2016-0003 TR-2016-0003 EXPERIMENTAL STUDY OF ELECTRONIC QUANTUM INTERFERENCE , PHOTONIC CRYSTAL CAVITY, PHOTONIC BAND...EDGE EFFECTS FOR OPTICAL AMPLIFICATION Shawn-Yu Lin Rensselaer Polytechnic Institute 110 8th Street Troy, New York 12180 26 Jan 2016 Final Report...2014 – 11 Jan 2016 4. TITLE AND SUBTITLE Experimental Study of Electronic Quantum Interference , Photonic Crystal Cavity, Photonic Band Edge Effects

  19. Large spin Seebeck effects in zigzag-edge silicene nanoribbons

    International Nuclear Information System (INIS)

    Yang, Xi-Feng; Liu, Yu-Shen; Feng, Jin-Fu; Wang, Xue-Feng

    2014-01-01

    Using the first-principles methods, we investigate the thermospin properties of a two-probe model based on zigzag-edge silicene nanoribbons (ZSiNRs). Compared with the odd-width ZSiNRs, the spin Seebeck coefficient of the even-width ZSiNRs is obviously enhanced at room temperature. This fact is attributed to a nearly perfect symmetry of the linear conductance gap with the different spin index with respect to the Fermi level induced by the different parity of the wave functions. More interestingly, the corresponding charge Seebeck coefficient is near zero. Therefore, when a thermal bias is presented in the even-width ZSiNRs, a nearly pure spin current is achieved. Meanwhile, the spin polarization of the current approaches infinite

  20. Outsourcing CIS to achieve a cost-effective competitive edge

    International Nuclear Information System (INIS)

    Haines, A.

    2000-01-01

    The ability to survive in a competitive electricity market is a function of the ability of a service provider to deliver superior levels of customer service and develop new and innovative products and services. More and more, the foundation of these new services and products is the customer information system which has the capability to provide vast amounts of usage data and billing information; access to this data enables service providers to introduce new and innovative services and implement targeted marketing initiatives. Recent trend by progressive electricity providers appears to be to outsource specific information technology functions such as customer information systems (CIS) as a way to minimize capital investment, take advantage of leading edge technologies and leverage the expertise of niche service providers. Advantages of outsourcing, and factors important in the selection of an outsourcing partner are discussed

  1. Effect of gender on results of percutaneous edge-to-edge mitral valve repair with MitraClip system.

    Science.gov (United States)

    Estévez-Loureiro, Rodrigo; Settergren, Magnus; Winter, Reidar; Jacobsen, Per; Dall'Ara, Gianni; Sondergaard, Lars; Cheung, Gary; Pighi, Michele; Ghione, Matteo; Ihlemann, Nikolaj; Moat, Neil E; Price, Susanna; Streit Rosenberg, Tine; Di Mario, Carlo; Franzen, Olaf

    2015-07-15

    Knowledge regarding gender-specific results of percutaneous edge-to-edge mitral valve repair is scarce. The aim of this study was to investigate gender differences in outcomes in a cohort of patients treated with MitraClip implantation. A multicenter registry of 173 patients treated with MitraClip prostheses from 2009 to 2012 at 3 experienced centers was performed. One hundred nine patients (63%) were men. Men were younger (mean age 73 ± 10 vs 79 ± 9 years, p = 0.001) and had a higher prevalence of previous coronary bypass graft surgery (34% vs 13%, p = 0.002), previous myocardial infarction (46% vs 20%, p = 0.001), and diabetes mellitus (26% vs 11%, p = 0.020). There were no differences regarding New York Heart Association (NYHA) functional class before the intervention (NYHA class III or IV in 95% of men vs 97% of women, p = 0.472) or the cause of mitral regurgitation (MR) (functional in 58% of men vs 48% of women, p = 0.233). Men exhibited significantly larger ventricles (mean indexed left ventricular end-systolic diameter 2.4 ± 0.8 vs 2.0 ± 1.6 cm/m(2), p = 0.002, and mean indexed left ventricular end-diastolic volume 92.7 ± 46.1 vs 59.9 ± 24.6 ml/m(2), p effective treatment of MR in men and women. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Hanford Site Long-term Surface Barrier Development Program: Fiscal year 1994 highlights

    International Nuclear Information System (INIS)

    Petersen, K.L.; Link, S.O.; Gee, G.W.

    1995-08-01

    The Hanford Site Surface Barrier Development Program was organized in 1985 to test the effectiveness of various barrier designs in minimizing the effects of water infiltration; plant, animal and human intrusion; and wind and water erosion on buried wastes, plus preventing or minimizing the emanation of noxious gases. A team of scientists from the Pacific Northwest Laboratory (PNL) and engineers from Westinghouse Hanford Company (WHC) direct the barrier development effort. ICF Kaiser Hanford Company, in conjunction with WHC and PNL, developed design drawings and construction specifications for a 5-acre prototype barrier. The highlight of efforts in FY 1994 was the construction of the prototype barrier. The prototype barrier was constructed on the Hanford Site at the 200 BP-1 Operable Unit of the 200 East Area. Construction was completed in August 1994 and monitoring instruments are being installed so experiments on the prototype barrier can begin in FY 1995. The purpose of the prototype barrier is to provide insights and experience with issues regarding barrier design, construction, and performance that have not been possible with individual tests and experiments conducted to date. Additional knowledge and experience was gained in FY 1994 on erosion control, physical stability, water infiltration control, model testing, Resource Conservation and Recovery Act (RCRA) comparisons, biointrusion control, long-term performance, and technology transfer

  3. Edge Effects on Community and Social Structure of Northern Temperate Deciduous Forest Ants

    Directory of Open Access Journals (Sweden)

    Valerie S. Banschbach

    2012-01-01

    Full Text Available Determining how ant communities are impacted by challenges from habitat fragmentation, such as edge effects, will help us understand how ants may be used as a bioindicator taxon. To assess the impacts of edge effects upon the ant community in a northern temperate deciduous forest, we studied edge and interior sites in Jericho, VT, USA. The edges we focused upon were created by recreational trails. We censused the ants at these sites for two consecutive growing seasons using pitfall traps and litter plot excavations. We also collected nests of the most common ant species at our study sites, Aphaenogaster rudis, for study of colony demography. Significantly greater total numbers of ants and ant nests were found in the edge sites compared to the interior sites but rarefaction analysis showed no significant difference in species richness. Aphaenogaster rudis was the numerically dominant ant in the habitats sampled but had a greater relative abundance in the interior sites than in the edge sites both in pitfall and litter plot data. Queen number of A. rudis significantly differed between the nests collected in the edge versus the interior sites. Habitat-dependent changes in social structure of ants represent another possible indicator of ecosystem health.

  4. Hygrothermal effects on the tensile strength of carbon/epoxy laminates with molded edges

    Directory of Open Access Journals (Sweden)

    Cândido Geraldo Maurício

    2000-01-01

    Full Text Available The interlaminar stresses are confined to a region near the free edge. Therefore, the laminate stacking sequence and the free edge finishing are some of the factors that affect the strength of the laminate and limit its life. The use of molded edges eliminates the need for trimming and machining the laminates edges thus improving productivity. However, this fabrication technique may have a detrimental effect on the laminate strength for certain stacking sequences. This effect in the presence of moisture has not been characterized. This work presents the results of a comparative study of the resistance to delamination of laminates with machined edges and molded edges. Additionally, two environmental conditions were considered: dry laminates and laminates saturated with moisture. The tensile strength of the laminates were measured and micrographs were used to analyze the microstructure of the laminates near the free edges. It is concluded that the mechanical properties of advanced composites depend on the environmental conditions and the fabrication techniques used to produce the laminates. Therefore, it is necessary to account for these factors when experimentally determining the design allowables.

  5. How strong is the edge effect in the adsorption of anticancer drugs on a graphene cluster?

    Science.gov (United States)

    Rungnim, Chompoonut; Chanajaree, Rungroj; Rungrotmongkol, Thanyada; Hannongbua, Supot; Kungwan, Nawee; Wolschann, Peter; Karpfen, Alfred; Parasuk, Vudhichai

    2016-04-01

    The adsorption of nucleobase-analog anticancer drugs (fluorouracil, thioguanine, and mercaptopurine) on a graphene flake (C54H18) was investigated by shifting the site at which adsorption occurs from one end of the sheet to the other end. The counterpoise-corrected M06-2X/cc-pVDZ binding energies revealed that the binding stability decreases in the sequence thioguanine > mercaptopurine > fluorouracil. We found that adsorption near the middle of the sheet is more favorable than adsorption near the edge due to the edge effect. This edge effect is stronger for the adsorption of thioguanine or mercaptopurine than for fluorouracil adsorption. However, the edge effect reduces the binding energy of the drug to the flake by only a small amount, <5 kcal/mol, depending on the adsorption site and the alignment of the drug at this site.

  6. Stability of edge states and edge magnetism in graphene nanoribbons

    OpenAIRE

    Kunstmann, Jens; Özdoğan, Cem; Quandt, Alexander; Fehske, Holger

    2010-01-01

    We critically discuss the stability of edge states and edge magnetism in zigzag edge graphene nanoribbons (ZGNRs). We point out that magnetic edge states might not exist in real systems, and show that there are at least three very natural mechanisms - edge reconstruction, edge passivation, and edge closure - which dramatically reduce the effect of edge states in ZGNRs or even totally eliminate them. Even if systems with magnetic edge states could be made, the intrinsic magnetism would not be ...

  7. T Tank Farm Interim Surface Barrier Demonstration--Vadose Zone Monitoring Plan

    International Nuclear Information System (INIS)

    Zhang, Z. F.; Keller, Jason M.; Strickland, Christopher E.

    2007-01-01

    The Hanford Site has 149 underground single-shell tanks that store hazardous radioactive waste. Many of these tanks and their associated infrastructure (e.g., pipelines, diversion boxes) have leaked. Some of the leaked waste has entered the groundwater. The largest known leak occurred from the T-106 Tank in 1973. Many of the contaminants from that leak still reside within the vadose zone beneath the T Tank Farm. CH2M Hill Hanford Group, Inc. seeks to minimize movement of this residual contaminant plume by placing an interim barrier on the surface. Such a barrier is expected to prevent infiltrating water from reaching the plume and moving it further. A plan has been prepared to monitor and determine the effectiveness of the interim surface barrier. Soil water content and water pressure will be monitored using off-the-shelf equipment that can be installed by the hydraulic hammer technique. In fiscal year 2006, two instrument nests were installed. Each instrument nest contains a neutron probe access tube, a capacitance probe, four heat-dissipation units, and a drain gauge to measure soil water flux. A meteorological station has been installed outside of the fence. In fiscal year 2007, two additional instrument nests are planned to be installed beneath the proposed barrier.

  8. Hanford Site protective isolation surface barrier: Taking research and development to engineered application

    International Nuclear Information System (INIS)

    Myers, D.R.; Wing, N.R.

    1994-01-01

    The development of the Protective Isolation Surface Barrier has been an ongoing program since 1985. This development effort has focused on several technical areas. These technical areas include water infiltration, biointrusion, human intrusion, erosion/deposition, physical stability, barrier materials, computer modeling, long-term climate effects, natural analogs, and barrier design. This paper briefly reviews the results of the research and development in the technical areas and then explains how the results of this work have influenced the design features of the prototype barrier. A good example of this is to explain how the type and depth of the soil layer used in the barrier is related to water infiltration, biointrusion, modeling, climate, analogs, and barrier materials. Another good example is to explain the relationship of the barrier sideslopes (basalt riprap and native soil) with human intrusion, biointrusion, barrier materials, and barrier design. In general, the design features of the prototype barrier will be explained in terms of the results of the testing and development program. After the basis for prototype barrier design has been established, the paper will close by reviewing the construction of the prototype barrier, sharing the lessons learned during construction, and explaining the ongoing testing and monitoring program which will determine the success or failure of this barrier concept and the need for additional design modifications

  9. Effects of plasma shape and profiles on edge stability in DIII-D

    International Nuclear Information System (INIS)

    Lao, L.L.; Chan, V.S.; Chen, L.

    1998-12-01

    The results of recent experimental and theoretical studies concerning the effects of plasma shape and current and pressure profiles on edge instabilities in DIII-D are presented. Magnetic oscillations with toroidal mode number n ∼ 2--9 and a fast growth time γ -1 = 20--150 micros are often observed prior to the first giant type 1 ELM in discharges with moderate squareness. High n ideal ballooning second stability access encourages edge instabilities by facilitating the buildup of the edge pressure gradient and bootstrap current density which destabilize the intermediate to low n modes. Analysis suggests that discharges with large edge pressure gradient and bootstrap current density are more unstable to n > 1 modes. Calculations and experimental results show that ELM amplitude and frequency can be varied by controlling access to the second ballooning stability regime at the edge through variation of the squareness of the discharge shape. A new method is proposed to control edge instabilities by reducing access to the second ballooning stability regime at the edge using high order local perturbation of the plasma shape in the outboard bad curvature region

  10. Effects of plasma shape and profiles on edge stability in DIII-D

    International Nuclear Information System (INIS)

    Lao, L.L.; Ferron, J.R.; Miller, R.L.

    2001-01-01

    The results of recent experimental and theoretical studies concerning the effects of plasma shape and current and pressure profiles on edge instabilities in DIII-D are presented. Magnetic oscillations with toroidal mode number n∼2-9 and a fast growth time γ -1 =20-150μs are often observed prior to the first giant type I ELM in discharges with moderate squareness. High n ideal ballooning second stability access encourages edge instabilities by facilitating the buildup of the edge pressure gradient and bootstrap current density which destabilize the intermediate to low n modes. Analysis suggests that discharges with large edge pressure gradient and bootstrap current density are more unstable to n>1 modes. Calculations and experimental results show that ELM amplitude and frequency can be varied by controlling access to the second ballooning stability regime at the edge through variation of the squareness of the discharge shape. A new method is proposed to control edge instabilities by reducing access to the second ballooning stability regime at the edge using high order local perturbation of the plasma shape in the outboard bad curvature region. (author)

  11. The effects of habitat edges and trampling intensity on vegetation in urban forests

    OpenAIRE

    Hamberg, Leena

    2009-01-01

    Although changes in urban forest vegetation have been documented in previous Finnish studies, the reasons for these changes have not been studied explicitly. Especially, the consequences of forest fragmentation, i.e. the fact that forest edges receive more solar radiation, wind and air-borne nutrients than interiors have been ignored. In order to limit the change in urban forest vegetation we need to know why it occurs. Therefore, the effects of edges and recreational use of urban forests on ...

  12. Investigation of non thermal effects from the Dα line wings in edge plasmas

    International Nuclear Information System (INIS)

    Marandet, Y.; Godbert-Mouret, L.; Koubiti, M.; Stamm, R.; Capes, H.; Guirlet, R.

    2002-01-01

    The far wings of intense Dα lines measured at the edge of the Tore Supra Tokamak are found to exhibit a power-law behavior. The characteristic exponent is not far from two. Since the low density rules out thermal Stark broadening, we discuss non thermal effects which may arise from the edge plasma drift-wave turbulence. We suggest that both the Stark and the Doppler profile could be affected by the turbulence

  13. Experimental investigation of edge sheared flow development and configuration effects in the TJ-II stellarator

    International Nuclear Information System (INIS)

    Pedrosa, M.A.; Hidalgo, C.; Alonso, A.; Calderon, E.; Orozco, O.; Pablos, J.L. de

    2005-01-01

    Experimental results have shown that the generation of spontaneous perpendicular sheared flow (i.e. the naturally occurring shear layer) requires a minimum plasma density or gradient in the TJ-II stellarator. This finding has been observed by means of multiple plasma diagnostics, including probes, fast cameras, reflectometry and HIBP. The obtained shearing rate of the naturally occurring shear layer results in general comparable to the one observed during biasing-improved confinement regimes. It has been found that there is a coupling between the onset of sheared flow development and an increase in the level of plasma edge fluctuations pointing to turbulence as the main ingredient of the radial electric field drive; once the shear flow develops the level of turbulence tends to decrease. The link between the development of sheared flows and plasma density in TJ-II has been observed in different magnetic configurations and plasma regimes. Preliminary results show that the threshold density value depends on the iota value and on the magnetic ripple (plasma volume). Recent experiments carried out in the LHD stellarator have shown that edge sheared flows are also affected by the magnitude of edge magnetic ripple: the threshold density to trigger edge sheared flows increases with magnetic ripple . Those results have been interpreted as an evidence of the importance of neoclassical effect in the physics of ExB sheared flows. For some TJ-II magnetic configurations with higher edge iota (ι/2π≥ 1.8) there is a sharp increase in the edge density gradient simultaneous to a strong reduction of fluctuations and transport and a slight increase of the shearing rate and perpendicular rotation (≥2 km/s) as density increases above the threshold. The role of the edge ripple, the presence of edge rational surfaces and properties of turbulent transport are considered as possible ingredients to explain the spontaneous development of edge sheared flows in TJ-II. (author)

  14. The impact of edge effect on termite community (Blattodea: Isoptera) in fragments of Brazilian Atlantic Rainforest.

    Science.gov (United States)

    Almeida, C S; Cristaldo, P F; Florencio, D F; Ribeiro, E J M; Cruz, N G; Silva, E A; Costa, D A; Araújo, A P A

    2017-01-01

    Habitat fragmentation is considered to be one of the biggest threats to tropical ecosystem functioning. In this region, termites perform an important ecological role as decomposers and ecosystem engineers. In the present study, we tested whether termite community is negatively affected by edge effects on three fragments of Brazilian Atlantic Rainforest. Termite abundance and vegetation structure were sampled in 10 transects (15 × 2 m), while termite richness, activity, and soil litter biomass were measured in 16 quadrants (5 × 2 m) at forest edge and interior of each fragment. Habitat structure (i.e. number of tree, diameter at breast height and soil litter biomass) did not differ between forest edge and interior of fragments. Termite richness, abundance and activity were not affected by edge effect. However, differences were observed in the β diversity between forest edge and interior as well as in the fragments sampled. The β diversity partitioning indicates that species turnover is the determinant process of termite community composition under edge effect. Our results suggest that conservation strategies should be based on the selection of several distinct sites instead of few rich sites (e.g. nesting).

  15. Effect of ion temperature gradient driven turbulence on the edge-core connection for transient edge temperature sink

    International Nuclear Information System (INIS)

    Miyato, Naoaki

    2014-01-01

    Ion temperature gradient (ITG) driven turbulence simulation for a transient edge temperature sink localized in the poloidal plane is performed using a global Landau-fluid code in the electrostatic limit. Pressure perturbations with (m, n) = (±1, 0) are induced by the edge sink, where m and n are poloidal and toroidal mode numbers, respectively. It was found in the previous simulation that the nonlinear dynamics of these perturbations are responsible for the nonlocal plasma response/transport connecting edge and core in a toroidal plasma. Present simulation shows, however, that the ITG turbulence in the core region dissipates the large-scale (m, n) = (±1, 0) perturbations and weakens the edge-core connection observed in the previous simulation. (author)

  16. Determination of equilibrium factor between radon and its progeny using surface barrier detector for various shapes of passive radon dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, K. [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group; Fazal-ur-Rehman [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group; Ali, S. [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group; Khan, H.A. [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group

    1997-03-21

    In the field of radon dosimetry, it is customary to measure radon ({sup 222}Rn) concentration while potential health hazard is due to the radon short-lived progeny. When radon is in secular equilibrium, the measured activity of radon equals the activity of radon`s progeny. However, in practical cases an inequilibrium between radon and its progeny exists which is measured in terms of the equilibrium factor. To determine the equilibrium factor between radon and its progeny in a closed environment various shapes of passive dosimeters based upon solid state nuclear track detectors (SSNTDs) are employed. In order to observe the dependence of equilibrium factor upon shapes or effective volumes, experiments have been performed replacing the SSNTDs with a surface barrier detector in Karlsruhe diffusion chamber, pen-type and box-type dosimeters. Using the collected alpha spectra, the equilibrium factor has been determined for a radon-air mixture in a custom designed radon chamber simulating a closed environment of a room. The results show that the radon equilibrium factor is about 0.20 for different shapes of dosimeters studied in this research. It is concluded that the determination of equilibrium factor between radon and its progeny does not depend upon effective volume or shape of the passive dosimeters using alpha spectroscopic data acquired by surface barrier detector. (orig.).

  17. Determination of equilibrium factor between radon and its progeny using surface barrier detector for various shapes of passive radon dosimeters

    International Nuclear Information System (INIS)

    Jamil, K.; Fazal-ur-Rehman; Ali, S.; Khan, H.A.

    1997-01-01

    In the field of radon dosimetry, it is customary to measure radon ( 222 Rn) concentration while potential health hazard is due to the radon short-lived progeny. When radon is in secular equilibrium, the measured activity of radon equals the activity of radon's progeny. However, in practical cases an inequilibrium between radon and its progeny exists which is measured in terms of the equilibrium factor. To determine the equilibrium factor between radon and its progeny in a closed environment various shapes of passive dosimeters based upon solid state nuclear track detectors (SSNTDs) are employed. In order to observe the dependence of equilibrium factor upon shapes or effective volumes, experiments have been performed replacing the SSNTDs with a surface barrier detector in Karlsruhe diffusion chamber, pen-type and box-type dosimeters. Using the collected alpha spectra, the equilibrium factor has been determined for a radon-air mixture in a custom designed radon chamber simulating a closed environment of a room. The results show that the radon equilibrium factor is about 0.20 for different shapes of dosimeters studied in this research. It is concluded that the determination of equilibrium factor between radon and its progeny does not depend upon effective volume or shape of the passive dosimeters using alpha spectroscopic data acquired by surface barrier detector. (orig.)

  18. Risk Reduction Effects Due to the Start Time Extension of EDGs in OPR-1000

    International Nuclear Information System (INIS)

    Lim, Ho-Gon; Yang, Joon-Eon; Hwang, Mee-Jeong

    2006-01-01

    Under the condition that the ECCS rule in Korea will be revised based on the new U.S. 10 CFR 50.46, the risk impact due to the EDG start time extension is analyzed in the present study. This paper is composed of 6 sections. In the section 2, the LOCA break size that cannot be mitigable under the condition of extended EDG start time is obtained from the thermal hydraulic analysis. The section 3 discusses the frequency of the immitigable LOCA and the probability of the LOOP given a LOCA. In the section 4, the effect of the EDG start time extension on its failure probability is discussed with a qualitative manner. Finally, the whole risk change due to the EDG start time extension is calculated in the section 5 with the conclusions given in the section 6

  19. Does the edge effect influence plant community structure in a tropical dry forest?

    Directory of Open Access Journals (Sweden)

    Diogo Gallo Oliveira

    2013-04-01

    Full Text Available Edge effects are considered a key factor in regulating the structure of plant communities in different ecosystems. However, regardless to few studies, edge influence does not seem to be decisive in semiarid regions such as the Brazilian tropical dry forest known as Caatinga but this issue remains inconclusive. The present study tests the null hypothesis that the plant community of shrubs and trees does not change in its structure due to edge effects. Twenty-four plots (20 x 20 m were set up in a fragment of Caatinga, in which 12 plots were in the forest edges and 12 plots were inside the fragment. Tree richness, abundance and species composition did not differ between edge and interior plots. The results of this study are in agreement with the pattern previously found for semiarid environments and contrasts with previous results obtained in different environments such as Rainforests, Savanna and Forest of Araucaria, which indicate abrupt differences between the border and interior of the plant communities in these ecosystems, and suggest that the community of woody plants of the Caatinga is not ecologically affected by the presence of edges.

  20. The influence of anthropogenic edge effects on primate populations and their habitat in a fragmented rainforest in Costa Rica.

    Science.gov (United States)

    Bolt, Laura M; Schreier, Amy L; Voss, Kristofor A; Sheehan, Elizabeth A; Barrickman, Nancy L; Pryor, Nathaniel P; Barton, Matthew C

    2018-05-01

    When a forest is fragmented, this increases the amount of forest edge relative to the interior. Edge effects can lead to loss of animal and plant species and decreased plant biomass near forest edges. We examined the influence of an anthropogenic forest edge comprising cattle pasture, coconut plantations, and human settlement on the mantled howler (Alouatta palliata), white-faced capuchin (Cebus capucinus), Central American spider monkey (Ateles geoffroyi), and plant populations at La Suerte Biological Research Station (LSBRS), Costa Rica. We predicted that there would be lower monkey encounter rate, mean tree species richness, and diameter at breast height (DBH) in forest edge versus interior, and that monkeys would show species-specific responses to edge based on diet, body size, and canopy height preferences. Specifically, we predicted that howler monkeys would show positive or neutral edge effects due to their flexible folivorous diet, large body size, and preference for high canopy, capuchins would show positive edge effects due to their diverse diet, small body size, and preference for low to middle canopy, and spider monkeys would show negative edge effects due their reliance on ripe fruit, large body size, and preference for high upper canopy. We conducted population and vegetation surveys along edge and interior transects at LSBRS. Contrary to predictions, total monkey encounter rate did not vary between the forest edge and forest interior. Furthermore, all three species showed neutral edge effects with no significant differences in encounter rate between forest edge and interior. Interior transects had significantly higher mean tree species richness than edge transects, and interior trees had greater DBH than edge trees, although this difference was not significant. These results suggest that forest edges negatively impact plant populations at La Suerte but that the monkeys are able to withstand these differences in vegetation.

  1. Cerrado ground-dwelling ants (Hymenoptera: Formicidae as indicators of edge effects

    Directory of Open Access Journals (Sweden)

    Carlos Roberto F. Brandão

    2011-06-01

    Full Text Available Large-scale agricultural production in Brazil preferentially occupies plateaus reclaimed from areas originally covered by Cerrado (savanna. Depending on the region, a percentage of the pristine vegetation coverage must be preserved by law, resulting in the creation of fragmented legal Cerrado reserves. The geometry of these relatively small legal reserves creates new habitat edges and ecotones, whose effects on the invertebrate fauna are poorly understood. This study aimed to assess the effects of abrupt edges resulting from soy production on ground-dwelling ant assemblages in the Brazilian Cerrado. The study sites are located within the Amazon region, in the state of Maranhão, northern Brazil, but were covered by Cerrado on a relatively low plateau, irregularly inter-spaced with gallery forests along streams. We compared species richness and species composition of ground-dwelling ants along eight transects set 0, 50, 100, 150, 200, and 250 m into the sensu stricto Cerrado and 50 and 100 m into the soy field. The collecting periods covered the wet and dry seasons. Effects on ant species richness were non-significant, although composition of the assemblages was significantly affected by edge effects, which were, in part, found to be species specific. We hypothesize that edge effects are probably greater than estimated because of the shape and complexity of reserves. Consideration of edge effects in the Cerrado Biome should enable the design of appropriate reserve sizes and shapes to meet conservation goals.

  2. Application of dielectric surface barrier discharge for food storage

    Directory of Open Access Journals (Sweden)

    Yassine BELLEBNA

    2015-12-01

    Full Text Available Ozone (O3 is a powerful oxidizer and has much higher disinfection potential than chlorine and other disinfectants. Ozone finds its application mainly in water treatment and air purification Dielectric barrier discharge (DBD method has proved to be the best method to produce ozone. Dried air or oxygen is forced to pass through a 1-2 mm gap. The aim of this study was to show that disinfection system using ozone generated by dielectric barrier discharge (DBD is an effective alternative to be used in food industry and ensures a safe quality of air for optimum preservation of fruits and vegetables. The DBDs are specific kind of discharges because one (or sometimes both electrodes is covered by a dielectric material, thereby preventing the discharge to move towards electrical breakdown. A succession of microdischarges occurs rapidly; their "lifetime" is in the range of a few nanoseconds. One of their most important applications is the production of ozone for air treatment, used mainly in the area of food industry, for extending the storage life of foods. After the achievement of a surface DBD reactor of cylindrical shape and its electrical characterization, it was then used as an ozone generator for air disinfection. Obtained results have shown that this reactor used as an ozone generator is effective for disinfection of air by removing viruses, bacteria and pathogens, causing the slowdown of the ripening process of fruits and vegetables.

  3. Edge effects and beta diversity in ground and canopy beetle communities of fragmented subtropical forest.

    Science.gov (United States)

    Stone, Marisa J; Catterall, Carla P; Stork, Nigel E

    2018-01-01

    Clearing of dry forests globally creates edges between remnant forest and open anthropogenic habitats. We used flight intercept traps to evaluate how forest beetle communities are influenced by distance from such edges, together with vertical height, spatial location, and local vegetation structure, in an urbanising region (Brisbane, Australia). Species composition (but not total abundance or richness) differed greatly between ground and canopy. Species composition also varied strongly among sites at both ground and canopy levels, but almost all other significant effects occurred only at ground level, where: species richness declined from edge to interior; composition differed between positions near edges ( 50 m); high local canopy cover was associated with greater total abundance and richness and differing composition; and greater distances to the city centre were associated with increased total abundances and altered composition. Analyses of individual indicator species associated with this variation enabled further biological interpretations. A global literature synthesis showed that most spatially well-replicated studies of edge effects on ground-level beetles within forest fragments have likewise found that positions within tens of metres from edges with open anthropogenic habitats had increased species richness and different compositions from forest interior sites, with fewer effects on abundance. Accordingly, negative edge effects will not prevent relatively small compact fragments (if >10-20 ha) from supporting forest-like beetle communities, although indirect consequences of habitat degradation remain a threat. Retention of multiple spatially scattered forest areas will also be important in conserving forest-dependent beetles, given high levels of between-site diversity.

  4. Edge effects and beta diversity in ground and canopy beetle communities of fragmented subtropical forest

    Science.gov (United States)

    Catterall, Carla P.; Stork, Nigel E.

    2018-01-01

    Clearing of dry forests globally creates edges between remnant forest and open anthropogenic habitats. We used flight intercept traps to evaluate how forest beetle communities are influenced by distance from such edges, together with vertical height, spatial location, and local vegetation structure, in an urbanising region (Brisbane, Australia). Species composition (but not total abundance or richness) differed greatly between ground and canopy. Species composition also varied strongly among sites at both ground and canopy levels, but almost all other significant effects occurred only at ground level, where: species richness declined from edge to interior; composition differed between positions near edges ( 50 m); high local canopy cover was associated with greater total abundance and richness and differing composition; and greater distances to the city centre were associated with increased total abundances and altered composition. Analyses of individual indicator species associated with this variation enabled further biological interpretations. A global literature synthesis showed that most spatially well-replicated studies of edge effects on ground-level beetles within forest fragments have likewise found that positions within tens of metres from edges with open anthropogenic habitats had increased species richness and different compositions from forest interior sites, with fewer effects on abundance. Accordingly, negative edge effects will not prevent relatively small compact fragments (if >10–20 ha) from supporting forest-like beetle communities, although indirect consequences of habitat degradation remain a threat. Retention of multiple spatially scattered forest areas will also be important in conserving forest-dependent beetles, given high levels of between-site diversity. PMID:29494680

  5. Low-temperature hydrogenation of diamond nanoparticles using diffuse coplanar surface barrier discharge at atmospheric pressure

    Czech Academy of Sciences Publication Activity Database

    Kromka, Alexander; Čech, J.; Kozak, Halyna; Artemenko, Anna; Ižák, Tibor; Čermák, Jan; Rezek, Bohuslav; Černák, M.

    2015-01-01

    Roč. 252, č. 11 (2015), s. 2602-2607 ISSN 0370-1972 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:68378271 Keywords : atmospheric plasma * diamond nanoparticles * diffuse coplanar surface barrier discharge * FTIR * XPS Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.522, year: 2015

  6. Finite element method calculations of GMI in thin films and sandwiched structures: Size and edge effects

    International Nuclear Information System (INIS)

    Garcia-Arribas, A.; Barandiaran, J.M.; Cos, D. de

    2008-01-01

    The impedance values of magnetic thin films and magnetic/conductor/magnetic sandwiched structures with different widths are computed using the finite element method (FEM). The giant magneto-impedance (GMI) is calculated from the difference of the impedance values obtained with high and low permeability of the magnetic material. The results depend considerably on the width of the sample, demonstrating that edge effects are decisive for the GMI performance. It is shown that, besides the usual skin effect that is responsible for GMI, an 'unexpected' increase of the current density takes place at the lateral edge of the sample. In magnetic thin films this effect is dominant when the permeability is low. In the trilayers, it is combined with the lack of shielding of the central conductor at the edge. The resulting effects on GMI are shown to be large for both kinds of samples. The conclusions of this study are of great importance for the successful design of miniaturized GMI devices

  7. Edge effects enhance carbon uptake and its vulnerability to climate change in temperate broadleaf forests.

    Science.gov (United States)

    Reinmann, Andrew B; Hutyra, Lucy R

    2017-01-03

    Forest fragmentation is a ubiquitous, ongoing global phenomenon with profound impacts on the growing conditions of the world's remaining forest. The temperate broadleaf forest makes a large contribution to the global terrestrial carbon sink but is also the most heavily fragmented forest biome in the world. We use field measurements and geospatial analyses to characterize carbon dynamics in temperate broadleaf forest fragments. We show that forest growth and biomass increase by 89 ± 17% and 64 ± 12%, respectively, from the forest interior to edge, but ecosystem edge enhancements are not currently captured by models or approaches to quantifying regional C balance. To the extent that the findings from our research represent the forest of southern New England in the United States, we provide a preliminary estimate that edge growth enhancement could increase estimates of the region's carbon uptake and storage by 13 ± 3% and 10 ± 1%, respectively. However, we also find that forest growth near the edge declines three times faster than that in the interior in response to heat stress during the growing season. Using climate projections, we show that future heat stress could reduce the forest edge growth enhancement by one-third by the end of the century. These findings contrast studies of edge effects in the world's other major forest biomes and indicate that the strength of the temperate broadleaf forest carbon sink and its capacity to mitigate anthropogenic carbon emissions may be stronger, but also more sensitive to climate change than previous estimates suggest.

  8. Effect of interaction strength on robustness of controlling edge dynamics in complex networks

    Science.gov (United States)

    Pang, Shao-Peng; Hao, Fei

    2018-05-01

    Robustness plays a critical role in the controllability of complex networks to withstand failures and perturbations. Recent advances in the edge controllability show that the interaction strength among edges plays a more important role than network structure. Therefore, we focus on the effect of interaction strength on the robustness of edge controllability. Using three categories of all edges to quantify the robustness, we develop a universal framework to evaluate and analyze the robustness in complex networks with arbitrary structures and interaction strengths. Applying our framework to a large number of model and real-world networks, we find that the interaction strength is a dominant factor for the robustness in undirected networks. Meanwhile, the strongest robustness and the optimal edge controllability in undirected networks can be achieved simultaneously. Different from the case of undirected networks, the robustness in directed networks is determined jointly by the interaction strength and the network's degree distribution. Moreover, a stronger robustness is usually associated with a larger number of driver nodes required to maintain full control in directed networks. This prompts us to provide an optimization method by adjusting the interaction strength to optimize the robustness of edge controllability.

  9. Edge effect and phenology in Erythroxylum tortuosum (Erythroxylaceae), a typical plant of the Brazilian Cerrado.

    Science.gov (United States)

    Ishino, M N; De Sibio, P R; Rossi, M N

    2012-08-01

    The edge of a forest fragment can be considered a zone of transition between the interior of the fragment and the surrounding habitat matrix. Plants along the edge are more exposed to disturbance and microclimate variation than interior plants, resulting in the so-called edge effect. In this study, we compared leaf area, fluctuating asymmetry and chemical (water, nitrogen and tannins) leaf traits between Erythroxylum tortuosum plants inhabiting the edge with those growing in the interior of a cerrado fragment in Brazil. We also describe the temporal variation in the vegetative and reproductive phenological events of E. tortuosum plants throughout the season. Nitrogen, leaf area and fluctuating asymmetry did not differ between the two plant groups. Young leaves of the edge plants had significantly higher levels of tannins and lower levels of water than those of interior plants. We suggest that differences in leaf chemical concentrations between edge and interior plants may occur due to factors such as light intensity, wind, temperature and leaf age rather than plant stress. With respect to plant phenology, most reproductive events occurred during the spring. Leaf buds and young leaves prevailed during the rainy season. In the dry season, however, the vegetative events decreased due to leaf senescence followed by leaf abscission.

  10. Effect of a serrated trailing edge on sound radiation from nearby quadrupoles.

    Science.gov (United States)

    Karimi, Mahmoud; Croaker, Paul; Kinns, Roger; Kessissoglou, Nicole

    2017-05-01

    A periodic boundary element technique is implemented to study the noise reduction capability of a plate with a serrated trailing edge under quadrupole excitation. It is assumed for this purpose that the quadrupole source tensor is independent of the trailing edge configuration and that the effect of the trailing edge shape is to modify sound radiation from prescribed boundary layer sources. The flat plate is modelled as a continuous structure with a finite repetition of small spanwise segments. The matrix equation formulated by the periodic boundary element method for this 3D acoustic scattering problem is represented as a block Toeplitz matrix. The discrete Fourier transform is employed in an iterative algorithm to solve the block Toeplitz system. The noise reduction mechanism for a serrated trailing edge in the near field is investigated by comparing contour plots obtained from each component of the quadrupole for unserrated and serrated trailing edge plate models. The noise reduction due to the serrated trailing edge is also examined as a function of the source location.

  11. An evaluation of edge effects in nutritional accessibility and availability measures: a simulation study.

    Science.gov (United States)

    Van Meter, Emily M; Lawson, Andrew B; Colabianchi, Natalie; Nichols, Michele; Hibbert, James; Porter, Dwayne E; Liese, Angela D

    2010-07-27

    This paper addresses the statistical use of accessibility and availability indices and the effect of study boundaries on these measures. The measures are evaluated via an extensive simulation based on cluster models for local outlet density. We define outlet to mean either food retail store (convenience store, supermarket, gas station) or restaurant (limited service or full service restaurants). We designed a simulation whereby a cluster outlet model is assumed in a large study window and an internal subset of that window is constructed. We performed simulations on various criteria including one scenario representing an urban area with 2000 outlets as well as a non-urban area simulated with only 300 outlets. A comparison is made between estimates obtained with the full study area and estimates using only the subset area. This allows the study of the effect of edge censoring on accessibility measures. The results suggest that considerable bias is found at the edges of study regions in particular for accessibility measures. Edge effects are smaller for availability measures (when not smoothed) and also for short range accessibility It is recommended that any study utilizing these measures should correct for edge effects. The use of edge correction via guard areas is recommended and the avoidance of large range distance-based accessibility measures is also proposed.

  12. An evaluation of edge effects in nutritional accessibility and availability measures: a simulation study

    Directory of Open Access Journals (Sweden)

    Porter Dwayne E

    2010-07-01

    Full Text Available Abstract Background This paper addresses the statistical use of accessibility and availability indices and the effect of study boundaries on these measures. The measures are evaluated via an extensive simulation based on cluster models for local outlet density. We define outlet to mean either food retail store (convenience store, supermarket, gas station or restaurant (limited service or full service restaurants. We designed a simulation whereby a cluster outlet model is assumed in a large study window and an internal subset of that window is constructed. We performed simulations on various criteria including one scenario representing an urban area with 2000 outlets as well as a non-urban area simulated with only 300 outlets. A comparison is made between estimates obtained with the full study area and estimates using only the subset area. This allows the study of the effect of edge censoring on accessibility measures. Results The results suggest that considerable bias is found at the edges of study regions in particular for accessibility measures. Edge effects are smaller for availability measures (when not smoothed and also for short range accessibility Conclusions It is recommended that any study utilizing these measures should correct for edge effects. The use of edge correction via guard areas is recommended and the avoidance of large range distance-based accessibility measures is also proposed.

  13. Edge effect on post-dispersal artificial seed predation in the southeastern Amazonia, Brazil

    Directory of Open Access Journals (Sweden)

    G. Penido

    Full Text Available This paper evaluates the post-dispersal artificial seed predation rates in two areas of the southeastern Amazon forest-savanna boundary, central Brazil. We conducted the survey in a disturbance regime controlled research site to verify if exists an edge effect in these rates and if the disturbance (in this case annual fire and no fire affects seed predation. We placed 800 peanuts seeds in each area at regular distance intervals from the fragment`s edge. Data were analyzed by a likelihood ratio model selection in generalized linear models (GLM. The complete model (with effects from edge distance and site and its interaction was significative (F3=4.43; p=0.005. Seeds had a larger predation rates in fragment’s interior in both areas, but in the controlled area (no disturbance this effect was less linear. This suggests an edge effect for post-dispersal seed predation, and that disturbances might alter these effects. Even if we exclude the site effect (grouping both areas together there is still a strong edge effect on seed predation rates (F3=32.679; p>0.001. We did not verify predator’s species in this study; however, the presence of several species of ants was extremely common in the seeds. The detection of an edge effect in only a short survey time suggests that there is heterogeneity in predation rates and that this variation might affect plant recruitment in fragmented areas of the Amazon forest. Henceforth, this seed predation should be taken in consideration in reforestation projects, where the main source of plants species is from seed distribution.

  14. Edge effect on post-dispersal artificial seed predation in the southeastern Amazonia, Brazil.

    Science.gov (United States)

    Penido, G; Ribeiro, V; Fortunato, D S

    2015-05-01

    This paper evaluates the post-dispersal artificial seed predation rates in two areas of the southeastern Amazon forest-savanna boundary, central Brazil. We conducted the survey in a disturbance regime controlled research site to verify if exists an edge effect in these rates and if the disturbance (in this case annual fire and no fire) affects seed predation. We placed 800 peanuts seeds in each area at regular distance intervals from the fragment`s edge. Data were analyzed by a likelihood ratio model selection in generalized linear models (GLM). The complete model (with effects from edge distance and site and its interaction) was significative (F3=4.43; p=0.005). Seeds had a larger predation rates in fragment's interior in both areas, but in the controlled area (no disturbance) this effect was less linear. This suggests an edge effect for post-dispersal seed predation, and that disturbances might alter these effects. Even if we exclude the site effect (grouping both areas together) there is still a strong edge effect on seed predation rates (F3=32.679; p>0.001). We did not verify predator's species in this study; however, the presence of several species of ants was extremely common in the seeds. The detection of an edge effect in only a short survey time suggests that there is heterogeneity in predation rates and that this variation might affect plant recruitment in fragmented areas of the Amazon forest. Henceforth, this seed predation should be taken in consideration in reforestation projects, where the main source of plants species is from seed distribution.

  15. The effective action for edge states in higher-dimensional quantum Hall systems

    International Nuclear Information System (INIS)

    Karabali, Dimitra; Nair, V.P.

    2004-01-01

    We show that the effective action for the edge excitations of a quantum Hall droplet of fermions in higher dimensions is generically given by a chiral bosonic action. We explicitly analyze the quantum Hall effect on complex projective spaces CP k , with a U(1) background magnetic field. The edge excitations are described by Abelian bosonic fields on S 2k-1 with only one spatial direction along the boundary of the droplet relevant for the dynamics. Our analysis also leads to an action for edge excitations for the case of the Zhang-Hu four-dimensional quantum Hall effect defined on S 4 with an SU(2) background magnetic field, using the fact that CP 3 is an S 2 -bundle over S 4

  16. Parity effect of bipolar quantum Hall edge transport around graphene antidots.

    Science.gov (United States)

    Matsuo, Sadashige; Nakaharai, Shu; Komatsu, Katsuyoshi; Tsukagoshi, Kazuhito; Moriyama, Takahiro; Ono, Teruo; Kobayashi, Kensuke

    2015-06-30

    Parity effect, which means that even-odd property of an integer physical parameter results in an essential difference, ubiquitously appears and enables us to grasp its physical essence as the microscopic mechanism is less significant in coarse graining. Here we report a new parity effect of quantum Hall edge transport in graphene antidot devices with pn junctions (PNJs). We found and experimentally verified that the bipolar quantum Hall edge transport is drastically affected by the parity of the number of PNJs. This parity effect is universal in bipolar quantum Hall edge transport of not only graphene but also massless Dirac electron systems. These results offer a promising way to design electron interferometers in graphene.

  17. Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects

    Energy Technology Data Exchange (ETDEWEB)

    Pankin, Alexei Y.; Kritz, Arnold H.

    2011-07-19

    Topics covered are: anomalous transport and E x B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies.

  18. Effects of density gradients and fluctuations at the plasma edge on ECEI measurements at ASDEX Upgrade

    NARCIS (Netherlands)

    Vanovac, B.; Wolfrum, E.; Denk, S. S.; Mink, F.; Laggner, F. M.; Birkenmeier, G.; Willensdorfer, M.; Viezzer, E.; Hoelzl, M.; Freethy, S. J.; Dunne, M. G.; Lessig, A.; Luhmann, N. C.; ASDEX Upgrade team,; EUROfusion MST1 Team,

    2018-01-01

    Electron cyclotron emission imaging (ECEI) provides measurements of electron temperature (T-e) and its fluctuations (delta T-e). However, when measuring at the plasma edge, in the steep gradient region, radiation transport effects must be taken into account. It is shown that due to these effects,

  19. Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects

    International Nuclear Information System (INIS)

    Pankin, Alexei Y.; Kritz, Arnold H.

    2011-01-01

    Topics covered are: anomalous transport and E f- B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies

  20. A Field-Based Technique for Teaching about Habitat Fragmentation and Edge Effects

    Science.gov (United States)

    Resler, Lynn M.; Kolivras, Korine N.

    2009-01-01

    This article presents a field technique that exposes students to the indirect effects of habitat fragmentation on plant distributions through studying edge effects. This assignment, suited for students in an introductory biogeography or resource geography class, increases students' knowledge of basic biogeographic concepts such as environmental…

  1. Does the edge effect impact on the measure of spatial accessibility to healthcare providers?

    Science.gov (United States)

    Gao, Fei; Kihal, Wahida; Le Meur, Nolwenn; Souris, Marc; Deguen, Séverine

    2017-12-11

    Spatial accessibility indices are increasingly applied when investigating inequalities in health. Although most studies are making mentions of potential errors caused by the edge effect, many acknowledge having neglected to consider this concern by establishing spatial analyses within a finite region, settling for hypothesizing that accessibility to facilities will be under-reported. Our study seeks to assess the effect of edge on the accuracy of defining healthcare provider access by comparing healthcare provider accessibility accounting or not for the edge effect, in a real-world application. This study was carried out in the department of Nord, France. The statistical unit we use is the French census block known as 'IRIS' (Ilot Regroupé pour l'Information Statistique), defined by the National Institute of Statistics and Economic Studies. The geographical accessibility indicator used is the "Index of Spatial Accessibility" (ISA), based on the E2SFCA algorithm. We calculated ISA for the pregnant women population by selecting three types of healthcare providers: general practitioners, gynecologists and midwives. We compared ISA variation when accounting or not edge effect in urban and rural zones. The GIS method was then employed to determine global and local autocorrelation. Lastly, we compared the relationship between socioeconomic distress index and ISA, when accounting or not for the edge effect, to fully evaluate its impact. The results revealed that on average ISA when offer and demand beyond the boundary were included is slightly below ISA when not accounting for the edge effect, and we found that the IRIS value was more likely to deteriorate than improve. Moreover, edge effect impact can vary widely by health provider type. There is greater variability within the rural IRIS group than within the urban IRIS group. We found a positive correlation between socioeconomic distress variables and composite ISA. Spatial analysis results (such as Moran's spatial

  2. Atomic physics effects on tokamak edge drift-tearing modes

    International Nuclear Information System (INIS)

    Hahm, T.S.

    1993-01-01

    The effects of ionization and charge exchange on the linear stability of drift-tearing modes are analytically investigated. In particular, the linear instability threshold Δ Th , produced by ion sound wave coupling [Phys. Rev. Lett. 40, 1500 (1978)] is modified. In the strongly collisional regime, the ionization breaks up the near cancellation of the perturbed electric field and the pressure gradient along the magnetic field, and increases the threshold. In the semicollisional regime, both ionization and charge exchange act as drag on the ion parallel velocity [Phys. Fluids B 4, 2567 (1992)], and consequently decrease the threshold by reducing the effectiveness of ion sound wave propagation

  3. Positive edge effects on forest-interior cryptogams in clear-cuts.

    Directory of Open Access Journals (Sweden)

    Alexandro Caruso

    Full Text Available Biological edge effects are often assessed in high quality focal habitats that are negatively influenced by human-modified low quality matrix habitats. A deeper understanding of the possibilities for positive edge effects in matrix habitats bordering focal habitats (e.g. spillover effects is, however, essential for enhancing landscape-level resilience to human alterations. We surveyed epixylic (dead wood inhabiting forest-interior cryptogams (lichens, bryophytes, and fungi associated with mature old-growth forests in 30 young managed Swedish boreal forest stands bordering a mature forest of high conservation value. In each young stand we registered species occurrences on coarse dead wood in transects 0-50 m from the border between stand types. We quantified the effect of distance from the mature forest on the occurrence of forest-interior species in the young stands, while accounting for local environment and propagule sources. For comparison we also surveyed epixylic open-habitat (associated with open forests and generalist cryptogams. Species composition of epixylic cryptogams in young stands differed with distance from the mature forest: the frequency of occurrence of forest-interior species decreased with increasing distance whereas it increased for open-habitat species. Generalists were unaffected by distance. Epixylic, boreal forest-interior cryptogams do occur in matrix habitats such as clear-cuts. In addition, they are associated with the matrix edge because of a favourable microclimate closer to the mature forest on southern matrix edges. Retention and creation of dead wood in clear-cuts along the edges to focal habitats is a feasible way to enhance the long-term persistence of epixylic habitat specialists in fragmented landscapes. The proposed management measures should be performed in the whole stand as it matures, since microclimatic edge effects diminish as the matrix habitat matures. We argue that management that aims to increase

  4. T-TY Tank Farm Interim Surface Barrier Demonstration - Vadose Zone Monitoring Plan

    International Nuclear Information System (INIS)

    Zhang, Z.F.; Strickland, Christopher E.; Field, Jim G.; Parker, Danny L.

    2010-01-01

    The Hanford Site has 149 underground single-shell tanks that store hazardous radioactive waste. Many of these tanks and their associated infrastructure (e.g., pipelines, diversion boxes) have leaked. Some of the leaked waste has entered the groundwater. The largest known leak occurred from the T-106 Tank of the 241-T Tank Farm in 1973. Five tanks are assumed to have leaked in the TY Farm. Many of the contaminants from those leaks still reside within the vadose zone within the T and TY Tank Farms. The Department of Energy's Office of River Protection seeks to minimize the movement of these contaminant plumes by placing interim barriers on the ground surface. Such barriers are expected to prevent infiltrating water from reaching the plumes and moving them further. The soil water regime is monitored to determine the effectiveness of the interim surface barriers. Soil-water content and water pressure are monitored using off-the-shelf equipment that can be installed by the hydraulic hammer technique. Four instrument nests were installed in the T Farm in fiscal year (FY) 2006 and FY2007; two nests were installed in the TY Farm in FY2010. Each instrument nest contains a neutron probe access tube, a capacitance probe, and four heat-dissipation units. A meteorological station has been installed at the north side of the fence of the T Farm. This document summarizes the monitoring methods, the instrument calibration and installation, and the vadose zone monitoring plan for interim barriers in T farm and TY Farm.

  5. On the effect of leading edge blowing on circulation control airfoil aerodynamics

    Science.gov (United States)

    Mclachlan, B. G.

    1987-01-01

    In the present context the term circulation control is used to denote a method of lift generation that utilizes tangential jet blowing over the upper surface of a rounded trailing edge airfoil to determine the location of the boundary layer separation points, thus setting an effective Kutta condition. At present little information exists on the flow structure generated by circulation control airfoils under leading edge blowing. Consequently, no theoretical methods exist to predict airfoil performance under such conditions. An experimental study of the flow field generated by a two dimensional circulation control airfoil under steady leading and trailing edge blowing was undertaken. The objective was to fundamentally understand the overall flow structure generated and its relation to airfoil performance. Flow visualization was performed to define the overall flow field structure. Measurements of the airfoil forces were also made to provide a correlation of the observed flow field structure to airfoil performance. Preliminary results are presented, specifically on the effect on the flow field structure of leading edge blowing, alone and in conjunction with trailing edge blowing.

  6. The agile edge managing projects effectively using agile scrum

    CERN Document Server

    Vanderjack, Brian

    2015-01-01

    This concise book is an effective source for understanding Agile Scrum development; why we use it and how it works. It will explain how work gets done in manageable iterations (sprints) and the team meetings that keep work on track (ceremonies). Also, since risk is a constant threat to any team-based project, managing risk in an Agile Scrum environment is specii cally discussed. This book is for: New Agile Scrum team members. Team leaders - this book describes the foundation of Agile Scrum, which can save time getting team members on the same page. Trainer/Educator of Agile Scrum - this book clearly defines Agile Scrum in a structured way so that students can learn how to effectively serve on an Agile team to improve their marketability. If you need to know Agile Scrum, this book will show you how to own it.

  7. The Double-Edged Effects of Social Media Terror Communication

    DEFF Research Database (Denmark)

    Nickel, Sandro

    2014-01-01

    This paper connects the effects of social media on terror/anti-terror communication with dynamics and consequences of surveillance. Citizens become via social media more independent from mass media and more interconnected. This is also valid when citizens engage in terror/anti-terror communication...... that social media contribute to extending surveillance: by being a temptation for intelligence services, by not resisting state authorities and via constructing threat perceptions among populations which in effect deliver security politicians ‘windows of opportunity’ in order to implement ever more....... However, via social media citizens also become targets of the ‘collect-it-all’ surveillance, which was revealed to the global public in 2013. I argue that due to such surveillance some citizens might start to censor themselves and that surveillance inflicts with a number of human rights. I further argue...

  8. Finite Element Analysis of the Effect on Edge Distance of the Tensile Bearing Capacity of Embedded Hanging Parts

    Directory of Open Access Journals (Sweden)

    Meng Xian Hong

    2016-01-01

    Full Text Available In order to explore the trend of tensile bearing capacity of embedded hanging parts when change the edge distance. Based on the finite element analysis software ABAQUS, the four simulation model was established. The buried depth and strength of concrete remain unchanged, but the edge distance was gradient change. By the load - displacement curve of every model known, the greater the edge distance, the greater the bearing capacity. When the edge distance reaches 1.5 times buried depth, the effect of increasing edge distance for improving the bearing capacity will be impaired.

  9. Effect of dynamical phase on the resonant interaction among tsunami edge wave modes

    Science.gov (United States)

    Geist, Eric L.

    2018-01-01

    Different modes of tsunami edge waves can interact through nonlinear resonance. During this process, edge waves that have very small initial amplitude can grow to be as large or larger than the initially dominant edge wave modes. In this study, the effects of dynamical phase are established for a single triad of edge waves that participate in resonant interactions. In previous studies, Jacobi elliptic functions were used to describe the slow variation in amplitude associated with the interaction. This analytical approach assumes that one of the edge waves in the triad has zero initial amplitude and that the combined phase of the three waves φ = θ1 + θ2 − θ3 is constant at the value for maximum energy exchange (φ = 0). To obtain a more general solution, dynamical phase effects and non-zero initial amplitudes for all three waves are incorporated using numerical methods for the governing differential equations. Results were obtained using initial conditions calculated from a subduction zone, inter-plate thrust fault geometry and a stochastic earthquake slip model. The effect of dynamical phase is most apparent when the initial amplitudes and frequencies of the three waves are within an order of magnitude. In this case, non-zero initial phase results in a marked decrease in energy exchange and a slight decrease in the period of the interaction. When there are large differences in frequency and/or initial amplitude, dynamical phase has less of an effect and typically one wave of the triad has very little energy exchange with the other two waves. Results from this study help elucidate under what conditions edge waves might be implicated in late, large-amplitude arrivals.

  10. Effect of Dynamical Phase on the Resonant Interaction Among Tsunami Edge Wave Modes

    Science.gov (United States)

    Geist, Eric L.

    2018-04-01

    Different modes of tsunami edge waves can interact through nonlinear resonance. During this process, edge waves that have very small initial amplitude can grow to be as large or larger than the initially dominant edge wave modes. In this study, the effects of dynamical phase are established for a single triad of edge waves that participate in resonant interactions. In previous studies, Jacobi elliptic functions were used to describe the slow variation in amplitude associated with the interaction. This analytical approach assumes that one of the edge waves in the triad has zero initial amplitude and that the combined phase of the three waves φ = θ 1 + θ 2 - θ 3 is constant at the value for maximum energy exchange ( φ = 0). To obtain a more general solution, dynamical phase effects and non-zero initial amplitudes for all three waves are incorporated using numerical methods for the governing differential equations. Results were obtained using initial conditions calculated from a subduction zone, inter-plate thrust fault geometry and a stochastic earthquake slip model. The effect of dynamical phase is most apparent when the initial amplitudes and frequencies of the three waves are within an order of magnitude. In this case, non-zero initial phase results in a marked decrease in energy exchange and a slight decrease in the period of the interaction. When there are large differences in frequency and/or initial amplitude, dynamical phase has less of an effect and typically one wave of the triad has very little energy exchange with the other two waves. Results from this study help elucidate under what conditions edge waves might be implicated in late, large-amplitude arrivals.

  11. Effect of Dynamical Phase on the Resonant Interaction Among Tsunami Edge Wave Modes

    Science.gov (United States)

    Geist, Eric L.

    2018-02-01

    Different modes of tsunami edge waves can interact through nonlinear resonance. During this process, edge waves that have very small initial amplitude can grow to be as large or larger than the initially dominant edge wave modes. In this study, the effects of dynamical phase are established for a single triad of edge waves that participate in resonant interactions. In previous studies, Jacobi elliptic functions were used to describe the slow variation in amplitude associated with the interaction. This analytical approach assumes that one of the edge waves in the triad has zero initial amplitude and that the combined phase of the three waves φ = θ 1 + θ 2 - θ 3 is constant at the value for maximum energy exchange (φ = 0). To obtain a more general solution, dynamical phase effects and non-zero initial amplitudes for all three waves are incorporated using numerical methods for the governing differential equations. Results were obtained using initial conditions calculated from a subduction zone, inter-plate thrust fault geometry and a stochastic earthquake slip model. The effect of dynamical phase is most apparent when the initial amplitudes and frequencies of the three waves are within an order of magnitude. In this case, non-zero initial phase results in a marked decrease in energy exchange and a slight decrease in the period of the interaction. When there are large differences in frequency and/or initial amplitude, dynamical phase has less of an effect and typically one wave of the triad has very little energy exchange with the other two waves. Results from this study help elucidate under what conditions edge waves might be implicated in late, large-amplitude arrivals.

  12. Modulation of electronic and magnetic properties in InSe nanoribbons: edge effect

    Science.gov (United States)

    Wu, Meng; Shi, Jun-jie; Zhang, Min; Ding, Yi-min; Wang, Hui; Cen, Yu-lang; Guo, Wen-hui; Pan, Shu-hang; Zhu, Yao-hui

    2018-05-01

    Quite recently, the two-dimensional (2D) InSe nanosheet has become a hot material with great promise for advanced functional nano-devices. In this work, for the first time, we perform first-principles calculations on the structural, electronic, magnetic and transport properties of 1D InSe nanoribbons with/without hydrogen or halogen saturation. We find that armchair ribbons, with various edges and distortions, are all nonmagnetic semiconductors, with a direct bandgap of 1.3 (1.4) eV for bare (H-saturated) ribbons, and have the same high electron mobility of about 103 cm2V‑1s‑1 as the 2D InSe nanosheet. Zigzag InSe nanoribbons exhibit metallic behavior and diverse intrinsic ferromagnetic properties, with the magnetic moment of 0.5–0.7 μ B per unit cell, especially for their single-edge spin polarization. The edge spin orientation, mainly dominated by the unpaired electrons of the edge atoms, depends sensitively on the edge chirality. Hydrogen or halogen saturation can effectively recover the structural distortion, and modulate the electronic and magnetic properties. The binding energy calculations show that the stability of InSe nanoribbons is analogous to that of graphene and better than in 2D InSe nanosheets. These InSe nanoribbons, with novel electronic and magnetic properties, are thus very promising for use in electronic, spintronic and magnetoresistive nano-devices.

  13. Disorder effects on helical edge transport in graphene under a strong tilted magnetic field

    Science.gov (United States)

    Huang, Chunli; Cazalilla, Miguel A.

    2015-10-01

    In a recent experiment, Young et al. [Nature (London) 505, 528 (2014), 10.1038/nature12800] observed a metal to insulator transition as well as transport through helical edge states in monolayer graphene under a strong, tilted magnetic field. Under such conditions, the bulk is a magnetic insulator which can exhibit metallic conduction through helical edges. It was found that the two-terminal conductance of the helical channels deviates from the expected quantized value (=e2/h per edge, at zero temperature). Motivated by this observation, we study the effect of disorder on the conduction through the edge channels. We show that, unlike for helical edges of topological insulators in semiconducting quantum wells, a disorder Rashba spin-orbit coupling does not lead to backscattering, at least to leading order. Instead, we find that the lack of perfect antialignment of the electron spins in the helical channels to be the most likely cause for backscattering arising from scalar (i.e., spin-independent) impurities. The intrinsic spin-orbit coupling and other time-reversal symmetry-breaking and/or sublattice parity-breaking potentials also lead to (subleading) corrections to the channel conductance.

  14. Numerical Analysis of Edge Over Coating and Baffle Effect on Hot-Dip Galvanizing

    Science.gov (United States)

    Bao, Chengren; Kang, Yonglin; Li, Yan

    2017-06-01

    In hot-dip galvanizing process, air jet wiping control is so crucial to determine the coating thickness and uniformity of the zinc layer on the steel strip. A numerical simulation of gas-jet wiping in hot-dip galvanizing was conducted to minimize the occurrence of edge over coating (EOC). The causes of EOC were identified by contrasting and analyzing the airflow fields on the strip edge with and without a baffle. The factors influencing the airflow field on the strip edge during the change in the gap between the baffle and the strip edge were also analyzed. The effect of the distance between the air knife and the strip was evaluated. Technological parameters with on-site guidance role were obtained by combining them with the actual production to elucidate the role of the baffle in restraining the occurrence of EOC. The uniform distribution of pressure and coating thickness on the strip is achieved when the distance of the baffle from the strip edge is about 0.3 times of the jetting distance.

  15. Effects of phonon broadening on x-ray near-edge spectra in molecular crystals

    Science.gov (United States)

    Vinson, John; Jach, Terrence; Elam, Tim; Denlinger, Jonathon

    2014-03-01

    Calculations of near-edge x-ray spectra are often carried out using the average atomic coordinates from x-ray or neutron scattering experiments or from density functional theory (DFT) energy minimization. This neglects disorder from thermal and zero-point vibrations. Here we look at the nitrogen K-edge of ammonium chloride and ammonium nitrate, comparing Bethe-Salpeter calculations of absorption and fluorescence to experiment. We find that intra-molecular vibrational effects lead to significant, non-uniform broadening of the spectra, and that for some features zero-point motion is the primary source of the observed shape.

  16. A model for the neoclassical toroidal viscosity effect on Edge plasma toroidal rotation

    Energy Technology Data Exchange (ETDEWEB)

    Miron, I.G. [National Institute for Laser, Plasma and Radiation Physics, Euratom-MEdC Association, Bucharest (Romania)

    2013-11-15

    A semianalytic expression for the edge plasma angular toroidal rotation frequency that includes the neoclassical toroidal viscosity braking influence is obtained. Based on the model presented in a previous paper [I.G. Miron, Contrib. Plasma Phys. 53, 214 (2013)], the less destabilizing error field spectrum is found in order to minimize the nonlinear effect of the NTV on the toroidal rotation of the edge of the plasma. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Soft X-Ray Magneto-optical Faraday Effect around Ni M2,3 Edges

    International Nuclear Information System (INIS)

    Kai, Chen; Ming-Qi, Cui; Fen, Yan; Li-Juan, Sun; Lei, Zheng; Chen-Yan, Ma; Shi-Bo, Xi; Yi-Dong, Zhao; Jia, Zhao

    2008-01-01

    We present magneto-optical (MO) Faraday spectra measured around the M 2,3 edges (60–70eV) of Ni films at the Beijing Synchrotron Radiation Facility (BSRF). A polarization analysis of the final state of the transmitted radiation from the Ni film is employed to determine the Faraday rotation at the edges. The MO effect becomes resonantly enhanced at the M 2,3 edges, and accordingly large values for the rotation angle β of 1.85 ± 0.19° for this ferromagnetic Ni film with thickness of 31 nm are measured. Without the magnetic field, the azimuthal angles do not shift; with parallel and antiparallel magnetic field the rotation angles shift in the opposite way and they are symmetrical. The uncertainty of Faraday rotation angles mainly comes from the data fitting and the state change of the beamline when the angles are measured

  18. Many-body effects in the mesoscopic x-ray edge problem

    International Nuclear Information System (INIS)

    Hentschel, Martina; Roeder, Georg; Ullmo, Denis

    2007-01-01

    Many-body phenomena, a key interest in the investigation of bulk solid state systems, are studied here in the context of the x-ray edge problem for mesoscopic systems. We investigate the many-body effects associated with the sudden perturbation following the x-ray exciton of a core electron into the conduction band. For small systems with dimensions at the nanoscale we find considerable deviations from the well-understood metallic case where Anderson orthogonality catastrophe and the Mahan-Nozieres-DeDominicis response cause characteristic deviations of the photoabsorption cross section from the naive expectation. Whereas the K-edge is typically rounded in metallic systems, we find a slightly peaked K-edge in generic mesoscopic systems with chaotic-coherent electron dynamics. Thus the behavior of the photoabsorption cross section at threshold depends on the system size and is different for the metallic and the mesoscopic case. (author)

  19. Effect of ICRH on the JET edge plasma with carbon and beryllium coated limiters

    International Nuclear Information System (INIS)

    Clement, S.; Erents, S.K.; Tagle, J.A.; Brinkschulte, H.; Bures, M.; De Kock, L.

    1990-01-01

    Investigation of the scrape-off Layer (SOL) at different poloidal positions has been carried out with Langmuir probes for limiter discharges with ion cyclotron resonance heating (ICRH) at JET. A comparison of the effects of ICRH on the edge is presented for operation with all carbon limiters, and for operation with a beryllium layer evaporated on the walls and limiters of JET. The behaviour of the SOL parameters is similar for both cases, although edge temperatures tend to be lower in the Be case. Measurements with probes between the belt limiters and close to the ICRH antennas show that the edge parameters in this region are strongly influenced by the vicinity of an active antenna. (orig.)

  20. INVESTIGATION OF THE EFFECTS OF DIFFERENT EDGE JOINT ELEMENTS ON DIAGONAL TENSILE STRENGTH IN FURNITURE EDGE JOINTS

    Directory of Open Access Journals (Sweden)

    Arif GÜRAY

    2002-01-01

    Full Text Available In this work, the diagonal tensile strength of furniture edge joints such as wooden dowel, minifix, and alyan screw was investigated in panel-constructed boards for Suntalam and MDF Lam. For this purpose, a diagonal tensile strength test was applied to the 72 samples. According to the results, the maximum diagonal tensile strength was found to be in MDF Lam boards that jointed with alyan screw.

  1. Arthropods on plants in a fragmented Neotropical dry forest: a functional analysis of area loss and edge effects.

    Science.gov (United States)

    González, Ezequiel; Salvo, Adriana; Valladares, Graciela

    2015-02-01

    Loss and fragmentation of natural ecosystems are widely recognized as the most important threats to biodiversity conservation, with Neotropical dry forests among the most endangered ecosystems. Area and edge effects are major factors in fragmented landscapes. Here, we examine area and edge effects and their interaction, on ensembles of arthropods associated to native vegetation in a fragmented Chaco Serrano forest. We analyzed family richness and community composition of herbivores, predators, and parasitoids on three native plant species in 12 fragments of varying size and at edge/interior positions. We also looked for indicator families by using Indicator Species Analysis. Loss of family richness with the reduction of forest fragment area was observed for the three functional groups, with similar magnitude. Herbivores were richer at the edges without interaction between edge and area effects, whereas predators were not affected by edge/interior position and parasitoid richness showed an interaction between area and position, with a steeper area slope at the edges. Family composition of herbivore, predator, and parasitoid assemblages was also affected by forest area and/or edge/interior situation. We found three indicator families for large remnants and five for edges. Our results support the key role of forest area for conservation of arthropods taxonomic and functional diversity in a highly threatened region, and emphasize the need to understand the interactions between area and edge effects on such diversity. © 2014 Institute of Zoology, Chinese Academy of Sciences.

  2. [Edge effect of the plant community structure on land-bridge islands in the Thousand Island Lake].

    Science.gov (United States)

    Su, Xiao-Fei; Yuan, Jin-Feng; Hu, Guang; Xu, Gao-Fu; Yu, Ming-Jian

    2014-01-01

    The research was conducted on 29 land-bridge islands in the Thousand Island Lake (TIL), where long-term monitoring plots were set up during 2009-2010. The community attributes including species richness, Shannon index, plant mean height, plant mean diameter at breast height (DBH) and plant density along the edge-interior gradient from edge to interior forest were calculated to investigate the edge effect. The results showed that the species richness and Shannon index were affected through the whole gradient (larger than 50 m), while the range of edge effect was 20-30 m on mean plant height, and 10 m on plant density and mean DBH. Community attributes differed significantly among the edge gradients. The species richness and Shannon index peaked at the intermediate edge gradient. Plant density decreased and plant mean height increased along the edge to interior gradient. All five community attributes were significantly associated with the edge gradient, also different functional groups, evergreen or deciduous species, trees or shrubs, shade tolerant or shade intolerant species, were differentially influenced by the edge effect. It was demonstrated the influence of edge effect on the fragmented forest community varied with community attributes and functional groups.

  3. The exponential edge-gradient effect in x-ray computed tomography

    International Nuclear Information System (INIS)

    Joseph, P.M.

    1981-01-01

    The exponential edge-gradient effect must arise in any X-ray transmission CT scanner whenever long sharp edges of high contrast are encountered. The effect is non-linear and is due to the interaction of the exponential law of X-ray attenuation and the finite width of the scanning beam in the x-y plane. The error induced in the projection values is proved to be always negative. While the most common effect is lucent streaks emerging from single straight edges, it is demonstrated that dense streaks from pairs of edges are possible. It is shown that an exact correction of the error is possible only under very special (and rather unrealistic) circumstances in which an infinite number of samples per beam width are available and all thin rays making up the beam can be considered parallel. As a practical matter, nevertheless, increased sample density is highly desirable in making good approximate corrections; this is demonstrated with simulated scans. Two classes of approximate correction algorithms are described and their effectiveness evaluated on simulated CT phantom scans. One such algorithm is also shown to work well with a real scan of a physical phantom on a machine that provides approximately four samples per beam width. (author)

  4. Road-edge effects on herpetofauna in a lowland Amazonian rainforest

    Science.gov (United States)

    Ross J. Maynard; Nathalie C. Aall; Daniel Saenz; Paul S. Hamilton; Matthew A. Kwiatkowski

    2016-01-01

    The impact of roads on the flora and fauna of Neotropical rainforest is perhaps the single biggest driver of habitat modification and population declines in these ecosystems. We investigated the road-edge effect of a low-use dirt road on amphibian and reptile abundance, diversity, and...

  5. 2.5D Simulation of basin-edge effects on the ground motion ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    The effects of basin-edge and soil velocity on the ground motion characteristics have been simulated ... Figure 1. 3-D and 2.5-D radial, transverse and vertical components of the radiation for .... sedimentary basin deserve a particular attention.

  6. Film cooling adiabatic effectiveness measurements of pressure side trailing edge cooling configurations

    Directory of Open Access Journals (Sweden)

    R. Becchi

    2015-12-01

    Full Text Available Nowadays total inlet temperature of gas turbine is far above the permissible metal temperature; as a consequence, advanced cooling techniques must be applied to protect from thermal stresses, oxidation and corrosion the components located in the high pressure stages, such as the blade trailing edge. A suitable design of the cooling system for the trailing edge has to cope with geometric constraints and aerodynamic demands; state-of-the-art of cooling concepts often use film cooling on blade pressure side: the air taken from last compressor stages is ejected through discrete holes or slots to provide a cold layer between hot mainstream and the blade surface. With the goal of ensuring a satisfactory lifetime of blades, the design of efficient trailing edge film cooling schemes and, moreover, the possibility to check carefully their behavior, are hence necessary to guarantee an appropriate metal temperature distribution. For this purpose an experimental survey was carried out to investigate the film covering performance of different pressure side trailing edge cooling systems for turbine blades. The experimental test section consists of a scaled-up trailing edge model installed in an open loop suction type test rig. Measurements of adiabatic effectiveness distributions were carried out on three trailing edge cooling system configurations. The baseline geometry is composed by inclined slots separated by elongated pedestals; the second geometry shares the same cutback configuration, with an additional row of circular film cooling holes located upstream; the third model is equipped with three rows of in-line film cooling holes. Experiments have been performed at nearly ambient conditions imposing several blowing ratio values and using carbon dioxide as coolant in order to reproduce a density ratio close to the engine conditions (DR=1.52. To extend the validity of the survey a comparison between adiabatic effectiveness measurements and a prediction by

  7. Effects of Density and Impurity on Edge Localized Modes in Tokamaks

    Science.gov (United States)

    Zhu, Ping

    2017-10-01

    Plasma density and impurity concentration are believed to be two of the key elements governing the edge tokamak plasma conditions. Optimal levels of plasma density and impurity concentration in the edge region have been searched for in order to achieve the desired fusion gain and divertor heat/particle load mitigation. However, how plasma density or impurity would affect the edge pedestal stability may have not been well known. Our recent MHD theory modeling and simulations using the NIMROD code have found novel effects of density and impurity on the dynamics of edge-localized modes (ELMs) in tokamaks. First, previous MHD analyses often predict merely a weak stabilizing effect of toroidal flow on ELMs in experimentally relevant regimes. We find that the stabilizing effects on the high- n ELMs from toroidal flow can be significantly enhanced with the increased edge plasma density. Here n denotes the toroidal mode number. Second, the stabilizing effects of the enhanced edge resistivity due to lithium-conditioning on the low- n ELMs in the high confinement (H-mode) discharges in NSTX have been identified. Linear stability analysis of the experimentally constrained equilibrium suggests that the change in the equilibrium plasma density and pressure profiles alone due to lithium-conditioning may not be sufficient for a complete suppression of the low- n ELMs. The enhanced resistivity due to the increased effective electric charge number Zeff after lithium-conditioning provides additional stabilization of the low- n ELMs. These new effects revealed in our theory analyses may help further understand recent ELM experiments and suggest new control schemes for ELM suppression and mitigation in future experiments. They may also pose additional constraints on the optimal levels of plasma density and impurity concentration in the edge region for H-mode tokamak operation. Supported by National Magnetic Confinement Fusion Science Program of China Grants 2014GB124002 and 2015GB

  8. Modeling the transient aerodynamic effects during the motion of a flexible trailing edge

    International Nuclear Information System (INIS)

    Wolff, T; Seume, J R

    2016-01-01

    Wind turbine blades have been becoming longer and more slender during the last few decades. The longer lever arm results in higher stresses at the blade root. Hence, the unsteady loads induced by turbulence, gust, or wind shear increase. One promising way to control these loads is to use flexible trailing edges near the blade tip. The unsteady effects which appear during the motion of a flexible trailing edge must be considered for the load calculation during the design process because of their high influence on aeroelastic effects and hence on the fatigue loads. This is not yet possible in most of the wind turbine simulation environments. Consequently, an empirical model is developed in the present study which accounts for unsteady effects during the motion of the trailing edge. The model is based on Fourier analyses of results generated with Reynolds-Averaged Navier-Stokes (RANS) simulations of a typical thin airfoil with a deformable trailing edge. The validation showed that the model fits Computational Fluid Dynamics (CFD) results simulated with a random time series of the deflection angle. (paper)

  9. A surface barrier detector for simultaneous detection of α and β particles

    International Nuclear Information System (INIS)

    Shiraishi, Fumio

    1981-01-01

    Semiconductor detectors are indispensable as the solid detectors with high energy resolution. Ge detectors are used for gamma-ray spectroscopy and its applied fields, while Si detectors are used as the detectors for charged particles such as α and β rays and low energy X-ray. In this paper, it is reported that the Si detector developed in the author's laboratory is suitable to monitor very weak radioactivity. The Si detector is a rectifier, but in order to capture radiation, it has large area and increased thickness, and a window is provided for incident charged particles. The Si detectors are classified into three types according to the manufacturing methods, namely surface barrier type, PN joint type and Li drift type. The Si detector introduced here is of surface barrier type, but it is characterized by the use of P-type Si with superhigh purity. The method of manufacturing this detector, its specifications and characteristics are described. Because of the surface barrier type, it can be produced simply in short time, and the yield of products is good. The stability is good, and the sensitivity is high, accordingly very weak radioactivity can be measured. As the examples of measurements, the results of uranium ore and fertilizer on the market are compared. Also the utilization as surface contamination meters is explained. (Kako, I.)

  10. Analyzing the edge effects in a Brazilian seasonally dry tropical forest.

    Science.gov (United States)

    Arruda, D M; Eisenlohr, P V

    2016-02-01

    Due to the deciduous nature of dry forests (widely known as seasonally dry tropical forests) they are subject to microclimatic conditions not experienced in other forest formations. Close examinations of the theory of edge effects in dry forests are still rare and a number of questions arise in terms of this topic. In light of this situation we examined a fragment of the dry forest to respond to the following questions: (I) Are there differences in canopy cover along the edge-interior gradient during the dry season? (II) How does the microclimate (air temperature, soil temperature, and relative humidity) vary along that gradient? (III) How does the microclimate influence tree species richness, evenness and abundance along that gradient? (IV) Are certain tree species more dominant closer to the forest edges? Regressions were performed to address these questions. Their coefficients did not significantly vary from zero. Apparently, the uniform openness of the forest canopy caused a homogeneous internal microclimate, without significant differentiation in habitats that would allow modifications in biotic variables tested. We conclude that the processes of edge effect commonly seen in humid forests, not was shared with the dry forest assessed.

  11. Effect of leading-edge geometry on boundary-layer receptivity to freestream sound

    Science.gov (United States)

    Lin, Nay; Reed, Helen L.; Saric, W. S.

    1991-01-01

    The receptivity to freestream sound of the laminar boundary layer over a semi-infinite flat plate with an elliptic leading edge is simulated numerically. The incompressible flow past the flat plate is computed by solving the full Navier-Stokes equations in general curvilinear coordinates. A finite-difference method which is second-order accurate in space and time is used. Spatial and temporal developments of the Tollmien-Schlichting wave in the boundary layer, due to small-amplitude time-harmonic oscillations of the freestream velocity that closely simulate a sound wave travelling parallel to the plate, are observed. The effect of leading-edge curvature is studied by varying the aspect ratio of the ellipse. The boundary layer over the flat plate with a sharper leading edge is found to be less receptive. The relative contribution of the discontinuity in curvature at the ellipse-flat-plate juncture to receptivity is investigated by smoothing the juncture with a polynomial. Continuous curvature leads to less receptivity. A new geometry of the leading edge, a modified super ellipse, which provides continuous curvature at the juncture with the flat plate, is used to study the effect of continuous curvature and inherent pressure gradient on receptivity.

  12. Mammographic x-ray unit kilovoltage test tool based on k-edge absorption effect.

    Science.gov (United States)

    Napolitano, Mary E; Trueblood, Jon H; Hertel, Nolan E; David, George

    2002-09-01

    A simple tool to determine the peak kilovoltage (kVp) of a mammographic x-ray unit has been designed. Tool design is based on comparing the effect of k-edge discontinuity of the attenuation coefficient for a series of element filters. Compatibility with the mammography accreditation phantom (MAP) to obtain a single quality control film is a second design objective. When the attenuation of a series of sequential elements is studied simultaneously, differences in the absorption characteristics due to the k-edge discontinuities are more evident. Specifically, when the incident photon energy is higher than the k-edge energy of a number of the elements and lower than the remainder, an inflection may be seen in the resulting attenuation data. The maximum energy of the incident photon spectra may be determined based on this inflection point for a series of element filters. Monte Carlo photon transport analysis was used to estimate the photon transmission probabilities for each of the sequential k-edge filter elements. The photon transmission corresponds directly to optical density recorded on mammographic x-ray film. To observe the inflection, the element filters chosen must have k-edge energies that span a range greater than the expected range of the end point energies to be determined. For the design, incident x-ray spectra ranging from 25 to 40 kVp were assumed to be from a molybdenum target. Over this range, the k-edge energy changes by approximately 1.5 keV between sequential elements. For this design 21 elements spanning an energy range from 20 to 50 keV were chosen. Optimum filter element thicknesses were calculated to maximize attenuation differences at the k-edge while maintaining optical densities between 0.10 and 3.00. Calculated relative transmission data show that the kVp could be determined to within +/-1 kV. To obtain experimental data, a phantom was constructed containing 21 different elements placed in an acrylic holder. MAP images were used to determine

  13. Mammographic x-ray unit kilovoltage test tool based on k-edge absorption effect

    International Nuclear Information System (INIS)

    Napolitano, Mary E.; Trueblood, Jon H.; Hertel, Nolan E.; David, George

    2002-01-01

    A simple tool to determine the peak kilovoltage (kVp) of a mammographic x-ray unit has been designed. Tool design is based on comparing the effect of k-edge discontinuity of the attenuation coefficient for a series of element filters. Compatibility with the mammography accreditation phantom (MAP) to obtain a single quality control film is a second design objective. When the attenuation of a series of sequential elements is studied simultaneously, differences in the absorption characteristics due to the k-edge discontinuities are more evident. Specifically, when the incident photon energy is higher than the k-edge energy of a number of the elements and lower than the remainder, an inflection may be seen in the resulting attenuation data. The maximum energy of the incident photon spectra may be determined based on this inflection point for a series of element filters. Monte Carlo photon transport analysis was used to estimate the photon transmission probabilities for each of the sequential k-edge filter elements. The photon transmission corresponds directly to optical density recorded on mammographic x-ray film. To observe the inflection, the element filters chosen must have k-edge energies that span a range greater than the expected range of the end point energies to be determined. For the design, incident x-ray spectra ranging from 25 to 40 kVp were assumed to be from a molybdenum target. Over this range, the k-edge energy changes by approximately 1.5 keV between sequential elements. For this design 21 elements spanning an energy range from 20 to 50 keV were chosen. Optimum filter element thicknesses were calculated to maximize attenuation differences at the k-edge while maintaining optical densities between 0.10 and 3.00. Calculated relative transmission data show that the kVp could be determined to within ±1 kV. To obtain experimental data, a phantom was constructed containing 21 different elements placed in an acrylic holder. MAP images were used to determine

  14. Relative biological effectiveness (RBE) and distal edge effects of proton radiation on early damage in vivo

    DEFF Research Database (Denmark)

    Sørensen, Brita Singers; Bassler, Niels; Nielsen, Steffen

    2017-01-01

    of the SOBP to behind the distal dose fall-off. Irradiations were performed with the same dose plan at all positions, corresponding to a dose of 31.25 Gy in the middle of the SOBP. Endpoint of the study was early skin damage of the foot, assessed by a mouse foot skin scoring system. RESULTS: The MDD50 values......, where LETd,z =1 was 3.3 keV/μm. CONCLUSIONS: Although there is a need to expand the current study to be able to calculate an exact enhancement ratio, an enhanced biological effect in vivo for early skin damage in the distal edge was demonstrated....

  15. Measurement of the effective atomic numbers of compounds with cerium near to the absorption edge

    International Nuclear Information System (INIS)

    Polat, Recep; Icelli, Orhan

    2010-01-01

    In order to measure atomic, molecular and electronic cross-section; the effective atomic number, density of electron and absorption jump factor, we have first measured μ t values of compounds which are determined by mixture rule using transmission method. In order to measure experimentally the effective atomic number within absorption jump factors of compounds with Ce, the X-ray source used Am-241 whose gamma rays were stopped at secondary source (Sm), thus producing Kα and Kβ X-ray emission. The most crucial finding in this study is that measurement of the effective atomic number is not appropriate near to the absorption edge and the effective atomic number is affected by near to the absorption edge. The results obtained have been compared with theoretical values.

  16. Quantifying edge effect extent and its impacts on carbon stocks across a degraded landscape in the Amazon using airborne lidar.

    Science.gov (United States)

    dos-Santos, M. N.; Keller, M.; Morton, D. C.; Longo, M.; Scaranello, M. A., Sr.; Pinagé, E. R.; Correa Pabon, R.

    2017-12-01

    Ongoing tropical forest degradation and forest fragmentation increases forest edge area. Forest edges experience hotter, drier, and windier conditions and greater exposure to fires compared to interior areas, which elevate rates of tree mortality. Previous studies have suggested that forests within 100 m from the edge may lose 36% of biomass during the first two decades following fragmentation, although such estimates are based on a limited number of experimental plots. Degraded forests behave differently from intact forests and quantifying edge effect extension in a degraded forest landscape is more challenging compared to experimental studies. To overcome these limitations, we used airborne lidar data to quantify changes in forest structure near 91 edges in a heavily degraded tropical forest in Paragominas Municipality, eastern Brazilian Amazon. Paragominas was a center of timber production in the 1990s. Today, the landscape is a mosaic of different agricultural uses, degraded, secondary and unmanaged forests. A total of 3000 ha of high density (mean density of 17.9 points/m2) lidar data were acquired in August/September 2013 and June/July 2014 over 30 transects (200 x 5000m), systematically distributed over the study area, using the Optech Orion M-200 laser scanning system. We adopted lidar-measured forest heights as the edge effect criteria and found that mean extent of edge effect was highly variable across degraded forests (150 ± 354m) and secondary forest fragments (265 ± 365m). We related the extent of forest edges to the historical disturbances identified in Landsat imagery since 1984. Contrary to previous studies, we found that carbon stocks along forest edges were not significantly lower than forest core biomass when edges were defined by previously estimated range of 100 and 300m. In frontier forests, ecological edge effect may be masked by the cumulative impact of historic forest degradation - an anthropogenic edge effect that extends beyond the

  17. Combined effect of matrix cracking and stress-free edge on delamination

    Science.gov (United States)

    Salpekar, S. A.; Obrien, T. K.

    1990-01-01

    The effect of the stress-free edge on the growth of local delaminations initiating from a matrix crack in (0 sub 2/90 sub 4) sub s and (+ or - 45.90 sub 4) sub s glass epoxy laminates is investigated using 3-D finite element analysis. The presence of high interlaminar normal stresses at the intersection (corner) of the matrix crack with the stress-free edge, suggests that a mode I delamination may initiate at the corners. The strain energy release rates (G) were calculated by modeling a uniform through-width delamination and two inclined delaminations at 10.6 deg and 45 deg to the matrix crack. All components of G have high values near the free edges. The mode I component of G is high at small delamination length and becomes zero for a delamination length of one-ply thickness. The total G values near the free edge agreed well with previously derived closed form solution. The quasi-3D solutions agreed well with the 3-D interior solutions.

  18. Environmental induced renormalization effects in quantum Hall edge states due to 1/f noise and dissipation

    International Nuclear Information System (INIS)

    Braggio, A; Ferraro, D; Sassetti, M; Carrega, M; Magnoli, N

    2012-01-01

    We propose a general mechanism for the renormalization of the tunnelling exponents in edge states of the fractional quantum Hall effect. Mutual effects of the coupling with out-of-equilibrium 1/f noise and dissipation are considered for both the Laughlin sequence and the composite co- and counter-propagating edge states with Abelian or non-Abelian statistics. For states with counter-propagating modes, we demonstrate the robustness of the proposed mechanism in the so-called disorder-dominated phase. Prototypes of these states, such as ν = 2/3 and ν = 5/2, are discussed in detail, and the rich phenomenology induced by the presence of a noisy environment is presented. The proposed mechanism could help justify the strong renormalizations reported in many experimental observations carried out at low temperatures. We show how environmental effects could affect the relevance of the tunnelling excitations, leading to important implications, in particular for the ν = 5/2 case. (paper)

  19. Edge states and integer quantum Hall effect in topological insulator thin films.

    Science.gov (United States)

    Zhang, Song-Bo; Lu, Hai-Zhou; Shen, Shun-Qing

    2015-08-25

    The integer quantum Hall effect is a topological state of quantum matter in two dimensions, and has recently been observed in three-dimensional topological insulator thin films. Here we study the Landau levels and edge states of surface Dirac fermions in topological insulators under strong magnetic field. We examine the formation of the quantum plateaux of the Hall conductance and find two different patterns, in one pattern the filling number covers all integers while only odd integers in the other. We focus on the quantum plateau closest to zero energy and demonstrate the breakdown of the quantum spin Hall effect resulting from structure inversion asymmetry. The phase diagrams of the quantum Hall states are presented as functions of magnetic field, gate voltage and chemical potential. This work establishes an intuitive picture of the edge states to understand the integer quantum Hall effect for Dirac electrons in topological insulator thin films.

  20. Effect of feed rate, workpiece hardness and cutting edge on subsurface residual stress in the hard turning of bearing steel using chamfer + hone cutting edge geometry

    International Nuclear Information System (INIS)

    Hua Jiang; Shivpuri, Rajiv; Cheng Xiaomin; Bedekar, Vikram; Matsumoto, Yoichi; Hashimoto, Fukuo; Watkins, Thomas R.

    2005-01-01

    Residual stress on the machined surface and the subsurface is known to influence the service quality of a component, such as fatigue life, tribological properties, and distortion. Therefore, it is essential to predict and control it for enhanced performance. In this paper, a newly proposed hardness based flow stress model is incorporated into an elastic-viscoplastic finite element model of hard turning to analyze process variables that affect the residual stress profile of the machined surface. The effects of cutting edge geometry and workpiece hardness as well as cutting conditions, such as feed rate and cutting speed, are investigated. Numerical analysis shows that hone edge plus chamfer cutting edge and aggressive feed rate help to increase both compressive residual stress and penetration depth. These predictions are validated by face turning experiments which were conducted using a chamfer with hone cutting edge for different material hardness and cutting parameters. The residual stresses under the machined surface are measured by X-ray diffraction/electropolishing method. A maximum circumferential residual stress of about 1700 MPa at a depth of 40 μm is reached for hardness of 62 HRc and feed rate of 0.56 mm/rev. This represents a significant increase from previously reported results in literatures. It is found from this analysis that using medium hone radius (0.02-0.05 mm) plus chamfer is good for keeping tool temperature and cutting force low, while obtaining desired residual stress profile

  1. Impact of edge states on device performance of phosphorene heterojunction tunneling field effect transistors.

    Science.gov (United States)

    Liu, Fei; Wang, Jian; Guo, Hong

    2016-10-27

    Black phosphorus (BP) tunneling field effect transistors (TFETs) using heterojunctions (Hes) are investigated by atomistic quantum transport simulations. It is observed that edge states have a great impact on the transport characteristics of BP He-TFETs, which results in the potential pinning effect and deterioration of gate control. However, the on-state current can be effectively enhanced by using hydrogen to saturate the edge dangling bonds in BP He-TFETs, by which means edge states are quenched. By extending layered BP with a smaller band gap to the channel region and modulating the BP thickness, the device performance of BP He-TFETs can be further optimized and can fulfil the requirements of the international technology road-map for semiconductors (ITRS) 2013 for low power applications. In 15 nm 3L-1L and 4L-1L BP He-TFETs along the armchair direction the on-state currents are over two times larger than the current required by ITRS 2013 and can reach above 10 3 μA μm -1 with the fixed off-state current of 10 pA μm -1 . It is also found that the ambipolar effect can be effectively suppressed in BP He-TFETs.

  2. A study of the effect of the position of an edge filter within a ratiometric wavelength measurement system

    International Nuclear Information System (INIS)

    Wu, Qiang; Wang, Pengfei; Semenova, Yuliya; Farrell, Gerald

    2010-01-01

    The effect of the position of an edge filter within a ratiometric wavelength measurement system was investigated based on three cases: (1) the reflected fibre Bragg grating (FBG) signal passes through both the reference arm and the edge filter arm, (2) the reflected FBG signal is connected directly to the edge filter arm and does not pass through the reference arm, (3) the edge filter sits in line with the FBG and thus the source power is filtered prior to reaching the FBG. Both numerical simulations and experimental results show that cases 1 and 2 have similar system performance whilst case 3 is the best arrangement which offers the highest wavelength resolution

  3. Edge turbulence effect on ultra-fast swept reflectometry core measurements in tokamak plasmas

    Science.gov (United States)

    Zadvitskiy, G. V.; Heuraux, S.; Lechte, C.; Hacquin, S.; Sabot, R.

    2018-02-01

    Ultra-fast frequency-swept reflectometry (UFSR) enables one to provide information about the turbulence radial wave-number spectrum and perturbation amplitude with good spatial and temporal resolutions. However, a data interpretation of USFR is quiet tricky. An iterative algorithm to solve this inverse problem was used in past works, Gerbaud (2006 Rev. Sci. Instrum. 77 10E928). For a direct solution, a fast 1D Helmholtz solver was used. Two-dimensional effects are strong and should be taken into account during data interpretation. As 2D full-wave codes are still too time consuming for systematic application, fast 2D approaches based on the Born approximation are of prime interest. Such methods gives good results in the case of small turbulence levels. However in tokamak plasmas, edge turbulence is usually very strong and can distort and broaden the probing beam Sysoeva et al (2015 Nucl. Fusion 55 033016). It was shown that this can change reflectometer phase response from the plasma core. Comparison between 2D full wave computation and the simplified Born approximation was done. The approximated method can provide a right spectral shape, but it is unable to describe a change of the spectral amplitude with an edge turbulence level. Computation for the O-mode wave with the linear density profile in the slab geometry and for realistic Tore-Supra density profile, based on the experimental data turbulence amplitude and spectrum, were performed to investigate the role of strong edge turbulence. It is shown that the spectral peak in the signal amplitude variation spectrum which rises with edge turbulence can be a signature of strong edge turbulence. Moreover, computations for misaligned receiving and emitting antennas were performed. It was found that the signal amplitude variation peak changes its position with a receiving antenna poloidal displacement.

  4. The influence of the edge effect on the skyrmion generation in a magnetic nanotrack

    Directory of Open Access Journals (Sweden)

    N. Ran

    2017-02-01

    Full Text Available Magnetic skyrmions might be used for building next-generation nanomagnetic and spintronic devices, as they have several perspective properties, such as topologically protected stability, nanoscale size, and ultra-low depinning current density. Here we study the influence of the edge effect on the current-induced generation of a magnetic skyrmion in a finite-length thin-film ferromagnetic nanotrack with interface-induced Dzyaloshinskii-Moriya interaction. It shows that a stable skyrmion or a bunch of skyrmions can be successfully generated as long as the distance between the current injection region and the nanotrack terminal is larger than a certain threshold. We investigate the failed skyrmion generation caused by the edge effect, which will lead to an error writing event. We also present the phase diagrams of the skyrmion generation obtained for different material and geometric parameters. Our results could be useful for designing skyrmion-based information storage devices.

  5. Modelling the cutting edge radius size effect for force prediction in micro milling

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; Jan, Slunsky

    2008-01-01

    This paper presents a theoretical model for cutting force prediction in micro milling, taking into account the cutting edge radius size effect, the tool run out and the deviation of the chip flow angle from the inclination angle. A parameterization according to the uncut chip thickness to cutting...... edge radius ratio is used for the parameters involved in the force calculation. The model was verified by means of cutting force measurements in micro milling. The results show good agreement between predicted and measured forces. It is also demonstrated that the use of the Stabler's rule...... is a reasonable approximation and that micro end mill run out is effectively compensated by the deflections induced by the cutting forces....

  6. Effect of flow obstacles with various leading and trailing edges on critical heat flux

    International Nuclear Information System (INIS)

    Pioro, I.L.; Groeneveld, D.C.; Groeneveld, D.C.; Cheng, S.C.; Antoshko, Y.V.

    2001-01-01

    A joint investigation has been performed by the University of Ottawa and Chalk River Laboratories that examined the effect of the shape of the leading and trailing edges of the turbulence enhancing devices ('flow obstacles') on critical heat flux (CHF). The objective of this study was to gain a better overall understanding of the limit of CHF improvement for various obstacle designs and the impact of flow conditions on the improvements. (author)

  7. Timing performances and edge effects of detectors worked from 6-in. silicon slices

    International Nuclear Information System (INIS)

    Aiello, S.; Anzalone, A.; Cardella, G.; Cavallaro, Sl.; De Filippo, E.; Di Pietro, A.; Femino, S.; Geraci, M.; Giustolisi, F.; Guazzoni, P.; Iacono Manno, M.; Lanzalone, G.; Lanzano, G.; Lo Nigro, S.; Musumarra, A.; Pagano, A.; Papa, M.; Pirrone, S.; Politi, G.; Porto, F.; Rizzo, F.; Sambataro, S.; Sperduto, M.L.; Sutera, C.; Zetta, L.

    1997-01-01

    Prototypes of new passivated implanted planar silicon detectors, obtained for the first time from 6 in. silicon slices, have been tested. The time and energy resolutions have been studied as a function of the type and energy of the detected particles, in order to test the performances of these detectors for time of flight measurements in the Chimera project. Some problems arising from edge effects observed in double-pad detectors have been solved by using a guard ring. (orig.)

  8. Role of the pump limiter throat-ergodic divertor effect on edge plasma

    International Nuclear Information System (INIS)

    Grosman, A.; Samain, A.; Ghendrih, P.; Capes, H.; Morera, J.P.

    1988-01-01

    A large part of the Tore Supra programme is devoted to plasma edge studies. Two types of such density control apparatus have been implemented, a set of pumps limiters and the ergodic divertor. The goal of the present paper is to investigate the effect of the pump limiter throat on pumping efficiency. We present also the possibilities of the ergodic divertor device to facilitate plasma pumping and power exhaust

  9. The giant Stark effect in armchair-edge phosphorene nanoribbons under a transverse electric field

    Science.gov (United States)

    Zhou, Benliang; Zhou, Benhu; Liu, Pu; Zhou, Guanghui

    2018-01-01

    We study the variation of electronic properties for armchair-edge phosphorene nanoribbons (APNRs) modulated by a transverse electric field. Within the tight-binding model Hamiltonian, and by solving the differential Schrödinger equation, we find that a band gap closure appears at the critical field due to the giant Stark effect for an APNR. The gap closure has no field polarity, and the gap varies quadratically for small fields but becomes linear for larger ones. We attribute the giant Stark effect to the broken edge degeneracy, i.e., the charge redistributions of the conduction band minimum and valence band maximum states localized at opposite edges induced by the field. By combined with the Green's function approach, it is shown that in the presence of the critical field a gap of density of states (DOS) disappears and a high value DOS turns up at the energy position of the band gap closure. Finally, as the field increases, we find the band gap decreases more rapidly and the gap closure occurs at smaller fields for wider ribbons. Both the band gap and DOS variations with the field show an insulator-metal transition induced by a transverse electric field for the APNR. Our results show that wider APNRs are more appreciable to design field-effect transistors.

  10. Effect of Percutaneous Edge-to-Edge Repair on Mitral Valve Area and Its Association With Pulmonary Hypertension and Outcomes.

    Science.gov (United States)

    Utsunomiya, Hiroto; Itabashi, Yuji; Kobayashi, Sayuki; Rader, Florian; Hussaini, Asma; Makar, Moody; Trento, Alfredo; Siegel, Robert J; Kar, Saibal; Shiota, Takahiro

    2017-08-15

    Percutaneous edge-to-edge repair using the MitraClip system causes reduction in mitral valve area (MVA). However, its clinical impact is not fully elucidated. This study assessed the impact of postprocedural MVA reduction on pulmonary hypertension and outcomes. A total of 92 patients with grades 3 to 4 + mitral regurgitation (MR) who underwent MitraClip therapy were retrospectively reviewed. Using intraprocedural, 3-dimensional transesophageal echocardiography, postprocedural MVA was obtained by 2 optimized planes through the medial and lateral orifices of the repaired valve. MVA was reduced by 60.1% immediately after MitraClip procedure (p <0.001). Postprocedural MVA correlated moderately with mean transmitral pressure gradient (TMPG) in the majority of patients (r = -0.56, p <0.001), but discordance of MVA and TMPG was observed in 40% of patients. In multivariable linear regression analysis, postprocedural MVA ≤1.94 cm 2 was independently associated with a blunted decrease in systolic pulmonary artery pressure at 1-month follow-up (β-estimate -4.63, 95% confidence interval -9.71 to -0.15, p = 0.042). Postprocedural MVA ≤1.94 cm 2 was an independent predictor of all-cause mortality and heart failure hospitalization after MitraClip (hazard ratio 4.28, 95% confidence interval 1.56 to 11.7, p = 0.005) even after adjustment for age, gender, atrial fibrillation, cause of MR, left ventricular systolic function, pre-existing pulmonary hypertension, and residual MR. After further adjustment for TMPG ≥5 mm Hg, postprocedural MVA ≤1.94 cm 2 remained predictive for adverse outcomes (p = 0.048). In conclusion, the intraprocedural assessment of MVA by 3-dimensional transesophageal echocardiography can predict hemodynamic response and postprocedural prognosis after MitraClip therapy. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Design and performance evaluation of a 1000-year evapotranspiration-capillary surface barrier.

    Science.gov (United States)

    Zhang, Zhuanfang Fred; Strickland, Christopher E; Link, Steven O

    2017-02-01

    Surface barrier technology is used to isolate radioactive waste and to reduce or eliminate recharge water to the waste zone for 1000 years or longer. However, the design and evaluation of such a barrier is challenging because of the extremely long design life. After establishing a set of design and performance objectives, a package of design solutions was developed for 1000-year surface barriers over nuclear waste sites. The Prototype Hanford Barrier (PHB) was then constructed in 1994 in the field over an existing waste site as a demonstration. The barrier was tested to evaluate surface-barrier design and performance at the field scale under conditions of enhanced and natural precipitation and of no vegetation. The monitoring data demonstrate that the barrier satisfied nearly all objectives in the past two decades. The PHB far exceeded the Resource Conservation and Recovery Act criteria, functioned in Hanford's semiarid climate, limited drainage to well below the 0.5 mm yr -1 performance criterion, limited runoff, and minimized erosion and bio-intrusion. Given the two-decade record of successful performance and consideration of the processes and mechanisms that could affect barrier stability and hydrology in the future, the results suggest the PHB is very likely to perform for its 1000-year design life. This conclusion is based on two assumptions: (1) the exposed subgrade receives protection against erosion and (2) institutional controls prevent inadvertent human activity at the barrier. The PHB design can serve as the basis for site-specific barriers over waste sites containing underground nuclear waste, uranium mine tailings, and hazardous mine waste. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. The influence of fast neutron irradiation on the noise properties of silicon surface-barrier detectors

    International Nuclear Information System (INIS)

    Dabrowski, W.; Korbel, K.

    1988-01-01

    The susceptibility to the fast neutron irradiation of silicon surface-barrier detectors has been investigated. It was shown that the 1/f-noise decreases substantially with increasing fluence in the range from 10 10 n/cm 2 to 10 11 n/cm 2 . The deterioration of the detector performance is caused mainly by the positively-charged defects induced by the radiation. The critical value of the neutron fluence, at which the detector performance begins to be worsened was also determined. 5 refs., 5 figs. (author)

  13. A peer review of the Hanford Site Permanent Isolation Surface Barrier Development Program

    International Nuclear Information System (INIS)

    Wing, N.R.

    1992-09-01

    A panel of technical experts was organized to peer review the Hanford Site Permanent Isolation Surface Barrier Development Program (BDP) and to provide a specific review of a preconceptual prototype barrier design initiated during fiscal year (FY) 1990. The technical peer review of the BDP and the prototype is being conducted in three phases, two of which have been completed. This document presents the peer review panel's findings on the first two phases of the peer review process. Biointrusion and water intrusion control are discussed, along with design life, vegetation, and climate impact

  14. Cooling Strategies for Vane Leading Edges in a Syngas Environment Including Effects of Deposition and Turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Ames, Forrest [Univ. of North Dakota, Grand Forks, ND (United States); Bons, Jeffrey [Univ. of North Dakota, Grand Forks, ND (United States)

    2014-09-30

    The Department of Energy has goals to move land based gas turbine systems to alternate fuels including coal derived synthetic gas and hydrogen. Coal is the most abundant energy resource in the US and in the world and it is economically advantageous to develop power systems which can use coal. Integrated gasification combined cycles are (IGCC) expected to allow the clean use of coal derived fuels while improving the ability to capture and sequester carbon dioxide. These cycles will need to maintain or increase turbine entry temperatures to develop competitive efficiencies. The use of coal derived syngas introduces a range of potential contaminants into the hot section of the gas turbine including sulfur, iron, calcium, and various alkali metals. Depending on the effectiveness of the gas clean up processes, there exists significant likelihood that the remaining materials will become molten in the combustion process and potentially deposit on downstream turbine surfaces. Past evidence suggests that deposition will be a strong function of increasing temperature. Currently, even with the best gas cleanup processes a small level of particulate matter in the syngas is expected. Consequently, particulate deposition is expected to be an important consideration in the design of turbine components. The leading edge region of first stage vanes most often have higher deposition rates than other areas due to strong fluid acceleration and streamline curvature in the vicinity of the surface. This region remains one of the most difficult areas in a turbine nozzle to cool due to high inlet temperatures and only a small pressure ratio for cooling. The leading edge of a vane often has relatively high heat transfer coefficients and is often cooled using showerhead film cooling arrays. The throat of the first stage nozzle is another area where deposition potentially has a strongly adverse effect on turbine performance as this region meters the turbine inlet flow. Based on roughness

  15. A direct heating model to overcome the edge effect in microplates.

    Science.gov (United States)

    Lau, Chun Yat; Zahidi, Alifa Afiah Ahmad; Liew, Oi Wah; Ng, Tuck Wah

    2015-01-01

    Array-based tests in a microplate format are complicated by the regional variation in results of the outer against the inner wells of the plate. Analysis of the evaporation mechanics of sessile drops showed that evaporation rate increase with temperature was due to changes in the heat of vaporization, density and diffusion coefficient. In simulations of direct bottom heating of standard microplates, considerable heat transfer via conduction from the side walls was found to be responsible for lower temperatures in the liquid in wells close to the edge. Applying a two temperature heating mode, 304 K at the side compared to 310 K at the bottom, allowed for a more uniform temperature distribution. Transparency microplates were found to inherently possess immunity to the edge effect problem due to the presence of air between the liquid and solid wall. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Uncovering edge states and electrical inhomogeneity in MoS2 field-effect transistors.

    Science.gov (United States)

    Wu, Di; Li, Xiao; Luan, Lan; Wu, Xiaoyu; Li, Wei; Yogeesh, Maruthi N; Ghosh, Rudresh; Chu, Zhaodong; Akinwande, Deji; Niu, Qian; Lai, Keji

    2016-08-02

    The understanding of various types of disorders in atomically thin transition metal dichalcogenides (TMDs), including dangling bonds at the edges, chalcogen deficiencies in the bulk, and charges in the substrate, is of fundamental importance for TMD applications in electronics and photonics. Because of the imperfections, electrons moving on these 2D crystals experience a spatially nonuniform Coulomb environment, whose effect on the charge transport has not been microscopically studied. Here, we report the mesoscopic conductance mapping in monolayer and few-layer MoS2 field-effect transistors by microwave impedance microscopy (MIM). The spatial evolution of the insulator-to-metal transition is clearly resolved. Interestingly, as the transistors are gradually turned on, electrical conduction emerges initially at the edges before appearing in the bulk of MoS2 flakes, which can be explained by our first-principles calculations. The results unambiguously confirm that the contribution of edge states to the channel conductance is significant under the threshold voltage but negligible once the bulk of the TMD device becomes conductive. Strong conductance inhomogeneity, which is associated with the fluctuations of disorder potential in the 2D sheets, is also observed in the MIM images, providing a guideline for future improvement of the device performance.

  17. Simulations of Turbulence in Tokamak Edge and Effects of Self-Consistent Zonal Flows

    Science.gov (United States)

    Cohen, Bruce; Umansky, Maxim

    2013-10-01

    Progress is reported on simulations of electromagnetic drift-resistive ballooning turbulence in the tokamak edge. This extends previous work to include self-consistent zonal flows and their effects. The previous work addressed simulation of L-mode tokamak edge turbulence using the turbulence code BOUT that solves Braginskii-based plasma fluid equations in tokamak edge domain. The calculations use realistic single-null geometry and plasma parameters of the DIII-D tokamak and produce fluctuation amplitudes, fluctuation spectra, and particle and thermal fluxes that compare favorably to experimental data. In the effect of sheared ExB poloidal rotation is included with an imposed static radial electric field fitted to experimental data. In the new work here we include the radial electric field self-consistently driven by the microturbulence, which contributes to the sheared ExB poloidal rotation (zonal flow generation). We present simulations with/without zonal flows for both cylindrical geometry, as in the UCLA Large Plasma Device, and for the DIII-D tokamak L-mode cases in to quantify the influence of self-consistent zonal flows on the microturbulence and the concomitant transport. This work was performed under the auspices of the U.S. Department of Energy under contract DE-AC52-07NA27344 at the Lawrence Livermore National Laboratory.

  18. Contextual influences in texture-segmentation: distinct effects from elements along the edge and in the texture-region.

    Science.gov (United States)

    Robol, Valentina; Grassi, Massimo; Casco, Clara

    2013-08-09

    Both neurophysiological and psychophysical evidence suggest a strong influence of context on texture-segmentation. Here we extend and further analyse this issue, with a particular focus on the underlying mechanism. Specifically, we use a texture-edge discrimination task and separately investigate the effect of elements far from and along the edge. Consistent with previous studies, we report both an iso-near contextual effect - whereby performance is better if elements along the edge are iso-oriented compared to ortho-oriented to the edge - as well as an ortho-far effect - whereby discrimination is higher when elements far from the edge are orthogonal to the edge. We found that backward mask, which is known to interrupt re-entrant processing from extrastriate areas, only interferes with the iso-near effect whereas perturbing orientation, position or contrast polarity of elements far from the edge only abolishes the ortho-far effect. This suggests that feedback processes may be involved in the iso-near effect. Instead, the ortho-far effect may be accounted for by recurrent interactions among 1st order filters. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Evaluation of edge enhancement effect of phase contrast imaging using newly-developed photostimulable phosphor plate

    International Nuclear Information System (INIS)

    Matsuo, Satoru; Morishita, Junji; Katafuchi, Tetsuro; Fujita, Hiroshi

    2012-01-01

    We investigated whether the use of a newly developed columnar-crystal-type photostimulable-phosphor plate (CP1M200, referred to as system C) helps to provide improved edge-enhanced effect in phase contrast imaging. Physical characteristics of 2 conventional particulate-crystal-type photostimulable-phosphor plates (RP-5PM, referred to as system A and RP-6M, referred to as system B) and system C were measured. Then, an acrylic plate phantom and RMI152 phantom were imaged using 3 types of plates, and the edge-enhancement effects were evaluated based on the profile curve of the acrylic plate phantom. Visual evaluation of the RMI152 phantom images was conducted. The results showed that the modulation transfer function (MTF) of system C was superior to those of the other systems. The WS of system C was superior to those of the other systems in the low frequency band region, and inferior to those of the other systems in the high frequency band region. The presence of an edge-enhanced image was not detectable in the profile curve of the acrylic plate in system A, although that was shown in systems B and C due to their excellent sharpness. In the visual image evaluation of the RMI152 phantom, image quality of system C was superior to those of the other systems. Phase contrast imaging with a digital detector of a columnar-crystal-type photostimulable-phosphor plate is considered to provide improved edge-enhancement over that of conventional plates. (author)

  20. Development of a coincidence system for radio-nuclide standardization using surface barrier detectors

    International Nuclear Information System (INIS)

    Koskinas, M.F.

    1988-01-01

    A system for the standardization of alpha-gamma or electron-X radionuclide emitters has been developed in the present work. The system consists of one or two surface barrier detectors for alpha or electron detection which are coupled to thin-window NaI (T1) crystals suitable for low energy X or gamma ray detection. The performance of the system has been verified by means of the standardization of 241 Am, 137 Cs and 109 Cd solutions. The activity has been obtained using the extrapolation method applied to the 4Πα-γ and 2Πe c -X coincidence technique. The surface barrier detection efficiency was varied by placing absorbers over the radioactive sources or by changing the source to detector distance. The results were compared to those obtained using conventional absolute systems based on gas-flow and pressurized 4Π proportional counters, or using radioactive solutions standardized in international comparisons spondored by the Bureau International des Poids et Mesures. The expect and measured activities agree within the experimental uncertainties which were: 0.2 % for 241 Am, 0.7% for 137 Cs and 0.6% for 109 Cd. The ratio between the probabilities of (electron capture + internal conversion) and internal conversion for the K-shell of 109 Cd has been determined. The result is: 2.8883 ± 0.016. (author) [pt

  1. P-type silicon surface barrier detector used for x-ray dosimetry

    International Nuclear Information System (INIS)

    Yamamoto, Hisao; Hatakeyama, Satoru; Norimura, Toshiyuki; Tsuchiya, Takehiko

    1983-01-01

    Responses to X-rays of a P-type surface barrier detector fabricated in our laboratory were studied, taking into consideration the dependence on the temperature in order to examine its applicability to dosimetry of short-range radiation. The study was also made in the case of N-type surface barrier detector. At room temperature, the short-circuit current increased linearly with exposure dose rate (15 - 50 R/min) for N- and P-type detectors. The open-circuit voltage showed a nonlinear dependence. With increasing temperature, the short-circuit current for the N-type detector was approximately constant up to 30 0 C and then decreased, though the open-circuit voltage decreased linearly. For the P- type detector, both open-circuit voltage and short-circuit current decreased almost linearly with increasing temperature. While a P-type detector is still open to some improvements, these results indicate that it can be used as a dosimeter. (author)

  2. Impact of electrode geometry on an atmospheric pressure surface barrier discharge

    Science.gov (United States)

    Hasan, M. I.; Morabit, Y.; Dickenson, A.; Walsh, J. L.

    2017-06-01

    Several of the key characteristics of an atmospheric pressure surface barrier discharge (SBD) are heavily dependent on the geometrical configuration of the plasma generating electrodes. This paper reveals that increasing the surface area of an SBD device by reducing the gaps within the electrodes can have major and unforeseen consequence on the discharge properties. It is experimentally demonstrated that a critical limit exists when reducing the diameter of a circular electrode gap below 5 mm, beyond which the required breakdown voltage increases exponentially and the power deposited in the discharge is impeded. Using a numerical model, it is shown that a reduced electrode gap diameter yields a decrease in the voltage difference between the electrode and dielectric surface, thus lowering the maximum electric field. This study indicates a link between the electrode geometry and the nature of the reactive chemistry produced in the plasma, findings which have wide-reaching implications for many applications where multiple closely packed surface barrier discharges are employed to achieve uniform and large area plasma processing.

  3. Design and performance evaluation of a 1000-year evapotranspiration-capillary surface barrier

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhuanfang Fred; Strickland, Christopher E.; Link, Steven O.

    2017-02-01

    Surface barrier technology is used to isolate radioactive waste and to reduce or eliminate recharge water to the waste zone for 1000 years or longer. However, the design and evaluation of such a barrier is challenging because of the extremely long design life. The Prototype Hanford Barrier (PHB) was designed as a 1000-year barrier with pre-determined design and performance objectives and demonstrated in field from 1994 to present. The barrier was tested to evaluate surface-barrier design and performance at the field scale under conditions of enhanced and natural precipitation and of no vegetation. The monitoring data demonstrate that the barrier satisfied nearly all key objectives. The PHB far exceeded the Resource Conservation and Recovery Act criteria, functioned in Hanford’s semiarid climate, limited drainage to well below the 0.5 mm yr-1 performance criterion, limited runoff, and minimized erosion. Given the two-decade record of successful performance and consideration of all the processes and mechanisms that could degrade the stability and hydrology in the future, the results suggest the PHB is very likely to perform for its 1000-year design life. This conclusion is based on two assumptions: (1) the exposed subgrade receives protection against erosion and (2) institutional controls prevent inadvertent human activity at the barrier. The PHB design can serve as the base for site-specific barriers over waste sites containing underground nuclear waste, uranium mine tailings, and hazardous mine waste.

  4. Disorder effect on chiral edge modes and anomalous Hall conductance in Weyl semimetals

    International Nuclear Information System (INIS)

    Takane, Yositake

    2016-01-01

    Typical Weyl semimetals host chiral surface states and hence show an anomalous Hall response. Although a Weyl semimetal phase is known to be robust against weak disorder, the effect of disorder on chiral states has not been fully clarified so far. We study the behavior of such chiral states in the presence of disorder and its consequences on an anomalous Hall response, focusing on a thin slab of Weyl semimetal with chiral surface states along its edge. It is shown that weak disorder does not disrupt chiral edge states but crucially affects them owing to the renormalization of a mass parameter: the number of chiral edge states changes depending on the strength of disorder. It is also shown that the Hall conductance is quantized when the Fermi level is located near Weyl nodes within a finite-size gap. This quantization of the Hall conductance collapses once the strength of disorder exceeds a critical value, suggesting that it serves as a probe to distinguish a Weyl semimetal phase from a diffusive anomalous Hall metal phase. (author)

  5. Investigation of the effects on Charpy impact characteristics by shape of pendulum striking edge

    International Nuclear Information System (INIS)

    Kawai, Toshihiko; Etoh, Mikio; Hanawa, Namio; Shibaike, Masayuki; Inoue, Kazuo.

    1983-01-01

    Charpy impact test is used versatilely and practically as the method of evaluating the toughness of metals. In Japan, usually the JIS type testing machines are used, but recently, the test with ASTM type testing machines has been often demanded for steel materials for export or for nuclear use. Accordingly, the testing machines of both types must be installed, the testing works become troublesome, and the costs of initial investment, maintenance, management and so on increase. When the standards in various countries were investigated, the stipulation on the various particulars of the testing machines was almost similar except the shape of striking edges, which are 8mm radius in ASTM and 2mm radius in other standards. Recently it was clarified that there was some difference between the impact values of high toughness steel using JIS and ASTM machines. In order to clarify the cause of this difference and to unify the shape of edges, the investigation was carried out by the working group. The investigation of the effect of the difference of edge shapes on impact values, the analysis of fracture phenomena in impact test and the consideration on the results are reported. ASTM type testing machines should not be used for mild steel when absorbed energy exceeds 10kgf-m. (Kako, I.)

  6. Numerical investigation of rarefaction effects in the vicinity of a sharp leading edge

    Science.gov (United States)

    Pan, Shaowu; Gao, Zhenxun; Lee, Chunhian

    2014-12-01

    This paper presents a study of rarefaction effect on hypersonic flow over a sharp leading edge. Both continuum approach and kinetic method: a widely spread commercial Computational Fluid Dynamics-Navior-Stokes-Fourier (CFD-NSF) software - Fluent together with a direct simulation Monte Carlo (DSMC) code developed by the authors are employed for simulation of transition regime with Knudsen number ranging from 0.005 to 0.2. It is found that Fluent can predict the wall fluxes in the case of hypersonic argon flow over the sharp leading edge for the lowest Kn case (Kn = 0.005) in current paper while for other cases it also has a good agreement with DSMC except at the location near the sharp leading edge. Among all of the wall fluxes, it is found that coefficient of pressure is the most sensitive to rarefaction while heat transfer is the least one. A parameter based on translational nonequilibrium and a cut-off value of 0.34 is proposed for continuum breakdown in this paper. The structure of entropy and velocity profile in boundary layer is analyzed. Also, it is found that the ratio of heat transfer coefficient to skin friction coefficient remains uniform along the surface for the four cases in this paper.

  7. Edge effects in a small pixel CdTe for X-ray imaging

    Science.gov (United States)

    Duarte, D. D.; Bell, S. J.; Lipp, J.; Schneider, A.; Seller, P.; Veale, M. C.; Wilson, M. D.; Baker, M. A.; Sellin, P. J.; Kachkanov, V.; Sawhney, K. J. S.

    2013-10-01

    Large area detectors capable of operating with high detection efficiency at energies above 30 keV are required in many contemporary X-ray imaging applications. The properties of high Z compound semiconductors, such as CdTe, make them ideally suitable to these applications. The STFC Rutherford Appleton Laboratory has developed a small pixel CdTe detector with 80 × 80 pixels on a 250 μm pitch. Historically, these detectors have included a 200 μm wide guard band around the pixelated anode to reduce the effect of defects in the crystal edge. The latest version of the detector ASIC is capable of four-side butting that allows the tiling of N × N flat panel arrays. To limit the dead space between modules to the width of one pixel, edgeless detector geometries have been developed where the active volume of the detector extends to the physical edge of the crystal. The spectroscopic performance of an edgeless CdTe detector bump bonded to the HEXITEC ASIC was tested with sealed radiation sources and compared with a monochromatic X-ray micro-beam mapping measurements made at the Diamond Light Source, U.K. The average energy resolution at 59.54 keV of bulk and edge pixels was 1.23 keV and 1.58 keV, respectively. 87% of the edge pixels present fully spectroscopic performance demonstrating that edgeless CdTe detectors are a promising technology for the production of large panel radiation detectors for X-ray imaging.

  8. CFD analysis of cascade effects in marine propellers with trailing edge modification

    DEFF Research Database (Denmark)

    Shin, Keun Woo; Andersen, Poul

    2015-01-01

    investigated intensively by viscous flow solvers, although RANS CFD is prevalent in marine industry nowadays. In the current work, the cascade effect of a marine propeller is analyzed by CFD simulations on a threedimensional propeller model with varying the number of blades. The influence of trailing......-edge configurations on the cascade effect is also investigated by simulating CFD with varying trailingedge thickness and slope. The reason why the trailingedge is handled rather than other parts of bladegeometry is that it can be modified without altering overall blade thrust significantly, because the loading...

  9. Diversity of galling insects in Styrax pohlii (Styracaceae: edge effect and use as bioindicators

    Directory of Open Access Journals (Sweden)

    Walter Santos de Araújo

    2011-12-01

    Full Text Available Impacts of forest fragmentation and edge effect on plant-herbivores interactions are relatively unknown, and the relationships between galling insects and their host plants are very susceptible to environmental variations. The goal of our study was to test the edge effect hypothesis for galling insects associated with Styrax pohlii (Styracaceae host plant. Samplings were conducted at a fragment of semi-deciduous forest in Goiânia, Goiás, Brazil. Thirty host plant individuals (15 at fragment edge and 15 in its interior were sampled in July of 2007; in each plant, 10 apical branches were collected at the top, middle and bottom crown levels. Our results supported the prediction of greater richness of gall morphotypes in the edge habitat compared with remnant interior. In a similar way, gall abundance and frequency of attacked leaves were also greater in the fragment edge. These findings consequently suggest a positive response of galling insect diversity to edge effect; in the Saint-Hilaire forest, this effect probably operates through the changes in microclimatic conditions of edge habitats, which results in an increased hygrothermal stress, a determinant factor to distribution patterns of galling insects. We also concluded that these organisms could be employed as biological indicators (i because of their host-specificity, (ii they are sensitive to changes in plant quality, and (iii present dissimilar and specific responses to local variation in habitat conditions. Rev. Biol. Trop. 59 (4: 1589-1597. Epub 2011 December 01.Los impactos de la fragmentación de los bosques y el efecto de borde sobre las interacciones planta-herbívoros son relativamente desconocidos, y las relaciones entre los insectos inductores de agallas y sus plantas hospederas son muy susceptibles a las variaciones ambientales. El objetivo de nuestro estudio fue probar la hipótesis de efecto de borde en los insectos inductores de agallas asociados con la planta hospedera

  10. Analyzing the effect of tool edge radius on cutting temperature in micro-milling process

    Science.gov (United States)

    Liang, Y. C.; Yang, K.; Zheng, K. N.; Bai, Q. S.; Chen, W. Q.; Sun, G. Y.

    2010-10-01

    Cutting heat is one of the important physical subjects in the cutting process. Cutting heat together with cutting temperature produced by the cutting process will directly have effects on the tool wear and the life as well as on the workpiece processing precision and surface quality. The feature size of the workpiece is usually several microns. Thus, the tiny changes of cutting temperature will affect the workpiece on the surface quality and accuracy. Therefore, cutting heat and temperature generated in micro-milling will have significantly different effect than the one in the traditional tools cutting. In this paper, a two-dimensional coupled thermal-mechanical finite element model is adopted to determine thermal fields and cutting temperature during the Micro-milling process, by using software Deform-2D. The effect of tool edge radius on effective stress, effective strain, velocity field and cutting temperature distribution in micro-milling of aluminum alloy Al2024-T6 were investigated and analyzed. Also, the transient cutting temperature distribution was simulated dynamically. The simulation results show that the cutting temperature in Micro-milling is lower than those occurring in conventional milling processes due to the small loads and low cutting velocity. With increase of tool edge radius, the maximum temperature region gradually occurs on the contact region between finished surfaced and flank face of micro-cutter, instead of the rake face or the corner of micro-cutter. And this phenomenon shows an obvious size effect.

  11. Effects of substrate anisotropy and edge diffusion on submonolayer growth during molecular beam epitaxy: A Kinetic Monte Carlo study

    International Nuclear Information System (INIS)

    Devkota, J.; Shrestha, S.P.

    2007-12-01

    We have performed Kinetic Monte Carlo simulation work to study the effect of diffusion anisotropy, bonding anisotropy and edge diffusion on island formation at different temperatures during the sub-monolayer film growth in Molecular Beam Epitaxy. We use simple cubic solid on solid model and event based Bortz, Kalos and Labowitch (BKL) algorithm on the Kinetic Monte Carlo method to simulate the physical phenomena. We have found that the island morphology and growth exponent are found to be influenced by substrate anisotropy as well as edge diffusion, however they do not play a significant role in island elongation. The growth exponent and island size distribution are observed to be influenced by substrate anisotropy but are negligibly influenced by edge diffusion. We have found fractal islands when edge diffusion is excluded and compact islands when edge diffusion is included. (author)

  12. Edge effects on foliar stable isotope values in a Madagascan tropical dry forest.

    Directory of Open Access Journals (Sweden)

    Brooke E Crowley

    Full Text Available Edge effects represent an inevitable and important consequence of habitat loss and fragmentation. These effects include changes in microclimate, solar radiation, or temperature. Such abiotic effects can, in turn, impact biotic factors. They can have a substantial impact on species, communities, and ecosystems. Here we examine clinal variations in stable carbon and nitrogen isotope values for trees along an edge-interior gradient in the dry deciduous forest at Ankarafantsika National Park. We predicted that soil respiration and differences in solar irradiance would result in stratified δ¹³C values where leaves collected close to the forest floor would have lower δ¹³C values than those growing higher up in the canopy. We also anticipated that plants growing at the savannah-forest boundary would have higher δ¹³C and δ¹⁵N values than plants growing in the forest interior. As expected, we detected a small but significant canopy effect. Leaves growing below 2 m from the forest floor exhibit δ¹³C values that are, on average, 1.1‰ lower than those growing above this threshold. We did not, however, find any relationship between foliar δ¹³C and distance from the edge. Unpredictably, we detected a striking positive relationship between foliar δ¹⁵N values and increasing distance into the forest interior. Variability in physiology among species, anthropogenic influence, organic input, and rooting depth cannot adequately explain this trend. Instead, this unexpected relationship most likely reflects decreasing nutrient or water availability, or a shift in N-sources with increasing distance from the savannah. Unlike most forest communities, the trees at Ampijoroa are growing in nutrient-limited sands. In addition to being nutrient poor, these well-drained soils likely decrease the amount of soil water available to forest vegetation. Continued research on plant responses to edge effects will improve our understanding of the conservation

  13. Effect of a Finite Trailing Edge Thickness on the Drag of Rectangular and Delta Wings at Supersonic Speeds

    National Research Council Canada - National Science Library

    Klunker, E

    1952-01-01

    The effect of a finite trailing-edge thickness on the pressure drag of rectangular and delta wings with truncated diamond-shaped airfoil sections with a given thickness ratio is studied for supersonic...

  14. HIGHER ORDER SPECIATION EFFECTS ON PLUTONIUM L3 X-RAY ABSORPTION NEAR EDGE SPECTRA.

    Energy Technology Data Exchange (ETDEWEB)

    Conradson, Steven D.; Abney, Kent D.; Begg, Bruce D.; Brady, Erik D.; Clark, David L.; den Auwer, Christophe; Ding, Mei; Dorhout, Peter K.; Espinosa-Faller, Francisco J.; Gordon, Pamela L.; Hess, Nancy J.; Hess, Ryan F.; Keogh, D. Webster; Lander, Gerard H.; Lupinetti, Anthony J.; Neu, Mary P.; Palmer, Phillip D.; Paviet-Hartmann, Patricia; Reilly, Sean D.; Runde, Wolfgang H.; Tait, C. Drew; Veirs, D. Kirk

    2003-06-09

    Pu L{sub 3} X-ray Near Edge Absorption Spectra for Pu(0-VII) are reported for more than 50 chalcogenides, chlorides, hydrates, hydroxides, nitrates, carbonates, oxy-hydroxides, and other compounds both as solids and in solution, and substituted in zirconlite, perovksite, and borosilicate glass. This large data base extends the known correlations between the energy and shape of these spectra from the usual association of the XANES with valence and site symmetry to higher order chemical effects. Because of the large number of compounds of these different types a number of novel and unexpected behaviors are observed.

  15. Effect of alpha drift and instabilities on tokamak plasma edge conditions

    International Nuclear Information System (INIS)

    Miley, G.H.; Choi, C.K.

    1983-01-01

    As suprathermal fusion products slow down in a Tokamak, their average drift is inward. The effect of this drift on the alpha heating and thermalization profiles is examined. In smaller TFTR-type devices, heating in the outer region can be cut in half. Also, the fusion-product energy-distribution near the plasma edge has a positive slope with increasing energy, representing a possible driving mechanism for micro-instabilities. Another instability that can seriously affect outer plasma conditions and shear Alfven transport of alphas is also considered

  16. The Effects of Vegetative Type, Edges, Fire History, Rainfall and Management in Fire-Maintained Habitat

    Science.gov (United States)

    Breininger, David R.; Foster, Tammy E.; Carter, Geoffrey M.; Duncan, Brean W.; Stolen, Eric D.; Lyon, James E.

    2018-01-01

    The combined effects of fire history, climate, and landscape features (e.g., edges) on habitat specialists need greater focus in fire ecology studies, which usually only emphasize characteristics of the most recent fire. Florida scrub-jays are an imperiled, territorial species that prefer medium (1.2-1.7 m) shrub heights, which are dynamic because of frequent fires. We measured short, medium, and tall habitat quality states annually within 10 ha grid cells (that represented potential territories) because fires and vegetative recovery cause annual variation in habitat quality. We used multistate models and model selection to test competing hypotheses about how transition probabilities vary between states as functions of environmental covariates. Covariates included vegetative type, edges (e.g., roads, forests), precipitation, openings (gaps between shrubs), mechanical cutting, and fire characteristics. Fire characteristics not only included an annual presence/absence of fire covariate, but also fire history covariates: time since the previous fire, the longest fire-free interval, and the number of repeated fires. Statistical models with support included many covariates for each transition probability, often including fire history, interactions and nonlinear relationships. Tall territories resulted from 28 years of fire suppression and habitat fragmentation that reduced the spread of fires across landscapes. Despite 35 years of habitat restoration and prescribed fires, half the territories remained tall suggesting a regime shift to a less desirable habitat condition. Edges reduced the effectiveness of fires in setting degraded scrub and flatwoods into earlier successional states making mechanical cutting an important tool to compliment frequent prescribed fires.

  17. Enhanced piezoelectric effect at the edges of stepped molybdenum disulfide nanosheets.

    Science.gov (United States)

    Song, Xiaoxue; Hui, Fei; Gilmore, Keith; Wang, Bingru; Jing, Guangyin; Fan, Zhongchao; Grustan-Gutierrez, Enric; Shi, Yuanyuan; Lombardi, Lucia; Hodge, Stephen A; Ferrari, Andrea C; Lanza, Mario

    2017-05-18

    The development of piezoelectric layered materials may be one of the key elements enabling expansion of nanotechnology, as they offer a solution for the construction of efficient transducers for a wide range of applications, including self-powered devices. Here, we investigate the piezoelectric effect in multilayer (ML) stepped MoS 2 flakes obtained by liquid-phase exfoliation, which is especially interesting because it may allow the scalable fabrication of electronic devices using large area deposition techniques (e.g. solution casting, spray coating, inkjet printing). By using a conductive atomic force microscope we map the piezoelectricity of the MoS 2 flakes at the nanoscale. Our experiments demonstrate the presence of electrical current densities above 100 A cm -2 when the flakes are strained in the absence of bias, and the current increases proportional to the bias. Simultaneously collected topographic and current maps demonstrate that the edges of stepped ML MoS 2 flakes promote the piezoelectric effect, where the largest currents are observed. Density functional theory calculations are consistent with the ring-like piezoelectric potential generated when the flakes are strained, as well as the enhanced piezoelectric effect at edges. Our results pave the way to the design of piezoelectric devices using layered materials.

  18. A model for managing edge effects in harvest scheduling using spatial optimization

    Science.gov (United States)

    Kai L. Ross; Sándor F. Tóth

    2016-01-01

    Actively managed forest stands can create new forest edges. If left unchecked over time and across space, forest operations such as clear-cuts can create complex networks of forest edges. Newly created edges alter the landscape and can affect many environmental factors. These altered environmental factors have a variety of impacts on forest growth and structure and can...

  19. Edge effect on palm diversity in rain forest fragments in western Ecuador

    DEFF Research Database (Denmark)

    Baez, S.; Balslev, Henrik

    2007-01-01

    to be idiosyncratic and to depend on the level of disturbance at edges. This paper explores how variation in forest structure at the edges of two old-growth forest fragments in a tropical rain forest in western Ecuador affects palms of different species, life-forms, and size classes. We investigate (1) how edge...

  20. Fabrication and characterization of surface barrier detector from commercial silicon substrate

    International Nuclear Information System (INIS)

    Costa, Fabio Eduardo da; Silva, Julio Batista Rodrigues da

    2015-01-01

    This work used 5 silicon substrates, n-type with resistivity between 500-20,000 Ω.cm, with 12 mm diameter and 1 mm thickness, from Wacker - Chemitronic, Germany. To produce the surface barrier detectors, the substrates were first cleaned, then, they were etched with HNO 3 solution. After this, a deposition of suitable materials on the crystal was made, to produce the desired population inversion of the crystal characteristics. The substrates received a 10 mm diameter gold contact in one of the surfaces and a 5 mm diameter aluminum in the other. The curves I x V and the energy spectra for 28 keV and 59 keV, for each of the produced detectors, were measured. From the 5 substrates, 4 of them resulted in detectors and one did not present even diode characteristics. The results showed that the procedures used are suitable to produce detectors with this type of silicon substrates. (author)

  1. The development of permanent isolation surface barriers: Hanford Site, Richland, Washington, U.S.A

    International Nuclear Information System (INIS)

    Wing, N.R.; Gee, G.W.

    1993-01-01

    Permanent isolation surface barriers are being developed to isolate wastes disposed of in situ (in place) at the US Department of Energy's Hanford Site in Washington State (USA). The current focus of development efforts is to design barriers that will function in a semiarid to subhumid climate, Emit infiltration and percolation of water through the waste zone to near-zero amounts, be maintenance free, and last up to 1000 years or more. A series of field tests, experiments, and lysimeter studies have been conducted for several years. The results of tests to date confirm that the Hanford barrier concepts are valid for both present and wetter climatic conditions. The data collected also have provided the foundation for the design of a large prototype barrier to be constructed later in 1993. This paper presents the results of some of the field tests, experiments, and lysimeter studies

  2. Engineered surface barriers for waste disposal sites: lysimeter facility design and construction

    International Nuclear Information System (INIS)

    Phillips, S.J.; Ruben, M.S.; Kirkham, R.R.

    1988-01-01

    A facility to evaluate performance of engineered surface carriers for confinement of buried wastes has been designed, constructed, and operations initiated. The Field Lysimeter Test Facility is located at the US Department of Energy's Hanford Site in Richland, Washington. The facility consists of 18 one-dimensional drainage and weighing lysimeters used to evaluate 7 replicated barrier treatments. Distinct layers of natural earth materials were used to construct layered soil and rock barriers in each lysimeter. These barrier designs are capable in principal of significantly reducing or precluding infiltration of meteoric water through barriers into underlying contaminated zones. This paper summarizes salient facility design and construction features used in testing of the Hanford Site's engineered surface barriers

  3. Correlation of DT and DD fusion neutron damage in silicon surface barrier detector

    International Nuclear Information System (INIS)

    Iida, Toshiyuki; Sueyoshi, Yasuhiro; Sunarno; Takahashi, Akito

    1994-01-01

    In order to examine the correlation of DT and DD fusion neutron damage in Si, a silicon surface barrier detector (Si-SBD) was irradiation with neutrons from a deuteron accelerator. The leakage current increased proportionally with neutron fluence, which determined the neutron damage constant for the Si-SBD. The correlation factor of the DT and DD neutron damage in the Si-SBD was determined from the ratio of the DT and DD neutron damage constants and was found to be 2.3. We also calculated the rate of DT and DD neutron displacement damage for Si by using the TRIM-90 computer program and actual data on neutron reactions in the Si-SBD. The correlation factor of DT and DD neutron damage from the calculation agreed with that from the Si-SBD irradiation experiment. (author)

  4. Silicon surface barrier detector and study of energy spectrum of alpha particles from radioactive source

    International Nuclear Information System (INIS)

    Verma, S.D.; Sinha, Vijaya

    1986-01-01

    The principles of working of three commonly used radiation detectors, namely ionization chambers, scintillation counters with photomultiplier tube (PMT) systems and semiconductor detectors are briefly discussed. Out of the semiconductor detectors, the silicon surface barrier (SSB) detector has distinct advantages for detection of radiations, alpha particles in particular. The experimental setup to obtain the energy spectrum of alpha particles from 241 Am source using SSB fabricated in the Physics Department of Gujarat University, Ahmedabad is described. Its performance is compared with scintillation counter using PMT. SSB detector shows a sharp peak of #approx # 3 per cent energy resolution. The factors affecting the peak, namely, electronic noise, source dependent factors and detector-dependent factors are discussed. A method of calibrating SSB detectors based on energy loss mechanism of alpha particles in thin absorbers is described. Applications of such detectors are indicated. (M.G.B.)

  5. Edge effects enhance selfing and seed harvesting efforts in the insect-pollinated Neotropical tree Copaifera langsdorffii (Fabaceae).

    Science.gov (United States)

    Tarazi, R; Sebbenn, A M; Kageyama, P Y; Vencovsky, R

    2013-06-01

    Edge effects may affect the mating system of tropical tree species and reduce the genetic diversity and variance effective size of collected seeds at the boundaries of forest fragments because of a reduction in the density of reproductive trees, neighbour size and changes in the behaviour of pollinators. Here, edge effects on the genetic diversity, mating system and pollen pool of the insect-pollinated Neotropical tree Copaifera langsdorffii were investigated using eight microsatellite loci. Open-pollinated seeds were collected from 17 seed trees within continuous savannah woodland (SW) and were compared with seeds from 11 seed trees at the edge of the savannah remnant. Seeds collected from the SW had significantly higher heterozygosity levels (Ho=0.780; He=0.831) than seeds from the edge (Ho=0.702; He=0.800). The multilocus outcrossing rate was significantly higher in the SW (tm=0.859) than in the edge (tm=0.759). Pollen pool differentiation was significant, however, it did not differ between the SW (=0.105) and the edge (=0.135). The variance effective size within the progenies was significantly higher in the SW (Ne=2.65) than at the edge (Ne=2.30). The number of seed trees to retain the reference variance effective size of 500 was 189 at the SW and 217 at the edge. Therefore, it is preferable that seed harvesting for conservation and environmental restoration strategies be conducted in the SW, where genetic diversity and variance effective size within progenies are higher.

  6. Effect of gender on results of percutaneous edge-to-edge mitral valve repair with MitraClip system

    DEFF Research Database (Denmark)

    Estévez-Loureiro, Rodrigo; Settergren, Magnus; Winter, Reidar

    2015-01-01

    ≤II in 73.1% of men vs 74.2% of women, p = 0.912). After a mean follow-up period of 16.1 ± 11.1 months, no difference was found between groups in the incidence of death or admission for heart failure (log-rank p = 0.798). In conclusion, MitraClip implantation seems to be an equally safe and effective...

  7. Non-LTE effects on the strength of the Lyman edge in quasar accretion disks

    Science.gov (United States)

    Stoerzer, H.; Hauschildt, P. H.; Allard, F.

    1994-01-01

    We have calculated UV/EUV (300 A which is less than or equal to lambda which is less than or equal to 1500 A) continuous energy distributions of accretion disks in the centers of active galactic nuclei (AGNs) for disk luminosities in the range 0.1 L(sub Edd) less than or equal to L(sub acc) less than 1.0 L(sub Edd) and central masses ranging from 10(exp 8) solar mass to 10(exp 9) solar mass. The vertical gas pressure structure of the disk and the disk height are obtained analytically; the temperature stratification and the resulting continuum radiation fields are calculated numerically. We have included non-Local Thermodynamic Equilibrium (LTE) effects of both the ionization equilibrium and the level populations of hydrogen and helium. We show that these non-LTE effects reduce the strength of the Lyman edge when comapred to the LTE case. In non-LTE we find that the edge can be weakly in emission or absorption for disks seen face-on, depending on the disk parameters.

  8. Effect of laminate edge conditions on the formation of microvoids in composite laminates

    Science.gov (United States)

    Anderson, J. P.; Altan, M. C.

    2015-05-01

    Manufacturing defects such as microvoids are common in thermoset composite components and are known to negatively affect their strength. The resin pressure developed in and the resin flow out from the laminates during cure have been reported to be the primary factors influencing the final void content of a composite component. In this work, the effect of laminate edge conditions during the cure process on the formation of microvoids was experimentally investigated. This was achieved by fabricating eight-ply laminates from TenCate® BT250/7781 prepreg in a hot-press at a constant cure pressure of 170 kPa while limiting the laminate perimeter available for resin flow by 0%, 25%, 50%, 75%, and 100%. The individual plies of these five laminates were conditioned at 99% relative humidity before curing to maximize the moisture present in the lay-up before fabrication. The presence of moisture in the lay-ups was expected to promote void formation and allow the effect of restricting flow at the edges of a laminate to be better identified. The restriction of resin outflow was found to cause the average characteristic void diameter to decrease by 17% and void content to rise by 33%. This phenomenon was identified to be a result of the outflow restriction increasing the number of voids trapped within the laminate and indicates that for laminates cured at low pressures resin outflow is the dominant mechanism for void reduction.

  9. EDGE EFFECT MODELING AND STUDY FOR THREE-CHIP RGB LIGHT-EMITTING DIODES

    Directory of Open Access Journals (Sweden)

    A. I. Podosinnikov

    2015-03-01

    Full Text Available Subject of study. The paper deals with light quality improvement of multi–chip RGB light-emitting diodes (LEDs and luminaries on their basis. In particular, we have studied the issues of the edge effect reducing, which is non–uniformity of color when observing the source of light under different angles as well as non-uniformity of color distribution on the illuminated surface. Methods. Experimental study of the edge effect has been performed, namely, the analysis of the halo at the periphery of the illuminated area and the non–uniformity of area at the surface of the screen illuminated with RGB LEDs with and without light concentrators. Modeling of illumination distribution at various distances from the source for the system containing four RGB LEDs with reflectors by ZEMAX software has been carried out. Assessment of the uniformity for light distribution via calculating the chromaticity coordinates has been performed. Main results. The possibility of modeling application at the stage of a luminary design is shown on the example of RGB LEDs for assessing the efficiency of light flux usage and colorimetric parameters. Suggested method simplifies significantly the design of luminaries and reduces associated costs. Practical relevance. The findings can be used in the design of luminaries based on RGB LEDs, including the ones with secondary optics elements.

  10. Effect of trailing edge ramp on cavity flow structures and pressure drag

    International Nuclear Information System (INIS)

    Pey, Yin Yin; Chua, Leok Poh; Siauw, Wei Long

    2014-01-01

    Highlights: • Trailing edge ramps were used to reduce unsteadiness and pressure drag of a cavity. • Proper Orthogonal Decomposition was used to educe the coherent structures. • The 30° ramp was successful in redistributing the energy content within the cavity. • The 30° ramp guides the flow smoothly out of the cavity, reducing flow impingement. • A substantial reduction of pressure drag was achieved by the 30° ramp. -- Abstract: The effects of trailing edge ramp modifications on time-averaged velocity and pressure distributions within a cavity with a length to depth ratio of 2, at a speed of 15 m/s were investigated. The ramp angles were varied at 30°, 45° and 60° and ramp heights were varied at 0.25 times and 0.5 times of cavity depth. The mean flow within the cavity differed significantly from the baseline case when ramp angle was 30° and 45° with ramp height 0.5 times of cavity depth. At these 2 configurations, moment about the center of the cavity floor was reduced significantly. These could be attributed to the more steady flow within the cavity as compared to the baseline case. Spatial correlation of velocity in the cavity of ramp angle 30° showed that internal cavity flow was less sensitive to flow changes in the shear layer as compared to the baseline case. In the same cavity, snapshot Proper Orthogonal Decomposition revealed a redistribution of energy content where energetic structures exist only in the shear layer as opposed to energetic structures in both the shear layer and internal cavity for the baseline case. A reduction of pressure drag was also observed as the gentle ramp angle of 30° guides the flow smoothly out of the cavity and reduces trailing edge impingement

  11. Structure of edge-state inner products in the fractional quantum Hall effect

    Science.gov (United States)

    Fern, R.; Bondesan, R.; Simon, S. H.

    2018-04-01

    We analyze the inner products of edge state wave functions in the fractional quantum Hall effect, specifically for the Laughlin and Moore-Read states. We use an effective description for these inner products given by a large-N expansion ansatz proposed in a recent work by J. Dubail, N. Read, and E. Rezayi [Phys. Rev. B 86, 245310 (2012), 10.1103/PhysRevB.86.245310]. As noted by these authors, the terms in this ansatz can be constrained using symmetry, a procedure we perform to high orders. We then check this conjecture by calculating the overlaps exactly for small system sizes and compare the numerics with our high-order expansion. We find the effective description to be very accurate.

  12. Numerical analysis of edge effects in side illuminated strip detectors for digital radiology

    CERN Document Server

    Krizaj, D

    2000-01-01

    The influence of edge defects on side illuminated X-ray strip detectors for digital radiology is investigated by numerical device modeling. By assuming positive fixed oxide charges on side and top surfaces simulations have shown strong curvature of the equipotential lines in the edge region. A fraction of the edge generated current surpasses the edge guard-ring junction and is collected by the readout strips. As a consequence, strips cannot be placed close to the edge of the structure and collection efficiency is reduced. An n-on-n instead of a p-on-n strip detector is proposed enabling collection of edge generated carriers by a very narrow guard-ring junction and placement of the readout strip close to the edge without increase of the strip leakage current.

  13. Effects of nuclear spins on the transport properties of the edge of two-dimensional topological insulators

    Science.gov (United States)

    Hsu, Chen-Hsuan; Stano, Peter; Klinovaja, Jelena; Loss, Daniel

    2018-03-01

    The electrons in the edge channels of two-dimensional topological insulators can be described as a helical Tomonaga-Luttinger liquid. They couple to nuclear spins embedded in the host materials through the hyperfine interaction, and are therefore subject to elastic spin-flip backscattering on the nuclear spins. We investigate the nuclear-spin-induced edge resistance due to such backscattering by performing a renormalization-group analysis. Remarkably, the effect of this backscattering mechanism is stronger in a helical edge than in nonhelical channels, which are believed to be present in the trivial regime of InAs/GaSb quantum wells. In a system with sufficiently long edges, the disordered nuclear spins lead to an edge resistance which grows exponentially upon lowering the temperature. On the other hand, electrons from the edge states mediate an anisotropic Ruderman-Kittel-Kasuya-Yosida nuclear spin-spin interaction, which induces a spiral nuclear spin order below the transition temperature. We discuss the features of the spiral order, as well as its experimental signatures. In the ordered phase, we identify two backscattering mechanisms, due to charge impurities and magnons. The backscattering on charge impurities is allowed by the internally generated magnetic field, and leads to an Anderson-type localization of the edge states. The magnon-mediated backscattering results in a power-law resistance, which is suppressed at zero temperature. Overall, we find that in a sufficiently long edge the nuclear spins, whether ordered or not, suppress the edge conductance to zero as the temperature approaches zero.

  14. Finite-size effect on the dynamic and sensing performances of graphene resonators: the role of edge stress.

    Science.gov (United States)

    Kim, Chang-Wan; Dai, Mai Duc; Eom, Kilho

    2016-01-01

    We have studied the finite-size effect on the dynamic behavior of graphene resonators and their applications in atomic mass detection using a continuum elastic model such as modified plate theory. In particular, we developed a model based on von Karman plate theory with including the edge stress, which arises from the imbalance between the coordination numbers of bulk atoms and edge atoms of graphene. It is shown that as the size of a graphene resonator decreases, the edge stress depending on the edge structure of a graphene resonator plays a critical role on both its dynamic and sensing performances. We found that the resonance behavior of graphene can be tuned not only through edge stress but also through nonlinear vibration, and that the detection sensitivity of a graphene resonator can be controlled by using the edge stress. Our study sheds light on the important role of the finite-size effect in the effective design of graphene resonators for their mass sensing applications.

  15. Even–odd effect on the edge states for zigzag phosphorene nanoribbons under a perpendicular electric field

    International Nuclear Information System (INIS)

    Zhou, Benliang; Zhou, Guanghui; Zhou, Benhu; Zhou, Xiaoying

    2017-01-01

    We study the variation of electronic property for zigzag-edge phosphorene nanoribbons (ZPNRs) under a perpendicular electric field (PEF). Using the tight-binding Hamiltonian combined with the surface lattice Green’s function (GF) approach, we show that the response of edge states to PEF for a N -ZPNR with even- or odd- N (number of zigzag chains) is qualitatively different. The field opens a gap between two edge bands near the Fermi energy for even- N ribbons, but for odd- N ones where the two edge bands are always nearly degenerated. This difference is originally from that the Stark-effect-induced energies at the upper and lower edges for even- and odd- N ZPNRs are different due to the peculiar lattice structure of phosphorene. In consequence, the electronic densities are more localized at the edges driven by the field for even- N ZPNRs but not for odd- N ones. This even–odd effect is also reflected in conductance, which indicates that the odd- N ZPNRs may be more suitable for the usage of field-effect transistor. (paper)

  16. ATEFlap aerodynamic model, a dynamic stall model including the effects of trailing edge flap deflection

    Energy Technology Data Exchange (ETDEWEB)

    Bergami, L.; Gaunaa, M.

    2012-02-15

    The report presents the ATEFlap aerodynamic model, which computes the unsteady lift, drag and moment on a 2D airfoil section equipped with Adaptive Trailing Edge Flap. The model captures the unsteady response related to the effects of the vorticity shed into the wake, and the dynamics of flow separation a thin-airfoil potential flow model is merged with a dynamic stall model of the Beddoes-Leishmann type. The inputs required by the model are steady data for lift, drag, and moment coefficients as function of angle of attack and flap deflection. Further steady data used by the Beddoes- Leishmann dynamic stall model are computed in an external preprocessor application, which gives the user the possibility to verify, and eventually correct, the steady data passed to the aerodynamic model. The ATEFlap aerodynamic model is integrated in the aeroelastic simulation tool HAWC2, thus al- lowing to simulate the response of a wind turbine with trailing edge flaps on the rotor. The algorithms used by the preprocessor, and by aerodynamic model are presented, and modifications to previous implementations of the aerodynamic model are briefly discussed. The performance and the validity of the model are verified by comparing the dynamic response computed by the ATEFlap with solutions from CFD simulations. (Author)

  17. Analyses of Effects of Cutting Parameters on Cutting Edge Temperature Using Inverse Heat Conduction Technique

    Directory of Open Access Journals (Sweden)

    Marcelo Ribeiro dos Santos

    2014-01-01

    Full Text Available During machining energy is transformed into heat due to plastic deformation of the workpiece surface and friction between tool and workpiece. High temperatures are generated in the region of the cutting edge, which have a very important influence on wear rate of the cutting tool and on tool life. This work proposes the estimation of heat flux at the chip-tool interface using inverse techniques. Factors which influence the temperature distribution at the AISI M32C high speed steel tool rake face during machining of a ABNT 12L14 steel workpiece were also investigated. The temperature distribution was predicted using finite volume elements. A transient 3D numerical code using irregular and nonstaggered mesh was developed to solve the nonlinear heat diffusion equation. To validate the software, experimental tests were made. The inverse problem was solved using the function specification method. Heat fluxes at the tool-workpiece interface were estimated using inverse problems techniques and experimental temperatures. Tests were performed to study the effect of cutting parameters on cutting edge temperature. The results were compared with those of the tool-work thermocouple technique and a fair agreement was obtained.

  18. Influence of edge effects on single event upset susceptibility of SOI SRAMs

    International Nuclear Information System (INIS)

    Gu, Song; Liu, Jie; Zhao, Fazhan; Zhang, Zhangang; Bi, Jinshun; Geng, Chao; Hou, Mingdong; Liu, Gang; Liu, Tianqi; Xi, Kai

    2015-01-01

    An experimental investigation of the single event upset (SEU) susceptibility for heavy ions at tilted incidence was performed. The differences of SEU cross-sections between tilted incidence and normal incidence at equivalent effective linear energy transfer were 21% and 57% for the silicon-on-insulator (SOI) static random access memories (SRAMs) of 0.5 μm and 0.18 μm feature size, respectively. The difference of SEU cross-section raised dramatically with increasing tilt angle for SOI SRAM of deep-submicron technology. The result of CRÈME-MC simulation for tilted irradiation of the sensitive volume indicates that the energy deposition spectrum has a substantial tail extending into the low energy region. The experimental results show that the influence of edge effects on SEU susceptibility cannot be ignored in particular with device scaling down

  19. Impurity and neutral effects on the dissipative drift wave in tokamak edge plasmas

    International Nuclear Information System (INIS)

    Zhang, Y.Z.; Mahajan, S.M.

    1991-05-01

    Possible destabilizing mechanisms for the liner electrostatic dissipative drift waves (in tokamak edge plasmas) are investigated in slab geometry. The effects of processes such as ionization, charge exchange, radiation, and rippling are examined. In particular, the impurity condensation associated with radiation cooling is evaluated appropriately for the drift wave ordering, which is found to be an important driving mechanism in contrast to the results of earlier studies. It also shown that the role of ionization is quite complicated, and depends strongly on the manner in which the equilibrium is achieved. The linear eigenmode equation is studied both analytically and numerically. For the range of parameters relevant to TEXT tokamak, both the charge exchange of the rippling effect are found to be unimportant for instability. 25 refs., 6 figs

  20. Influence of MHD effects and edge conditions on ITER helium ash accumulation and sustained ignition

    International Nuclear Information System (INIS)

    Redi, M.H.; Cohen, S.A.

    1990-06-01

    Dilution of reacting species by build-up of helium ash and its effect on ignition in the ITER tokamak have been studies in a series of simulations with the one-dimensional BALDUR transport code. Thermal diffusivities, obtained from ITER scaling laws and with radial variations observed in JET, gave τ E ∼ 2--4 sec. Refueling of deuterium and tritium maintained constant electron density, while carbon recycling was 100% and the helium ash recycling was varied from 1.0 to 0.5. Including MHD effects, specifically sawteeth and beta limits, we find that ignition can be sustained for 200 seconds with R helium = 0.95. These simulations, the only non-zero-dimensional, time-dependent simulations thus far made for ITER plasmas, emphasize that edge plasma conditions, MHD behavior, and helium particle transport are critical synergistic issues for sustained ignition. 27 refs., 2 figs., 1 tab

  1. Conveying Cutting-Edge Discoveries to Nonscientists: Effective Communication with Media

    Science.gov (United States)

    Gupta, Nikhil; Hamilton, Kathleen; Chamot, Joshua

    2013-07-01

    The benefits of using information and news media for disseminating cutting-edge scientific discoveries to the public are well known. Taxpayers and lawmakers need to be informed about the implications of public investments, young students' interest can be molded toward science- and technology-based careers, and public awareness of important issues can be raised by effectively using media. However, communication with news media is different from the means commonly used by scientists—journal publications and conference presentations. This article is intended to provide information on three basic aspects of media interactions—why, what, and how to communicate. The increasing importance of this mode of dissemination in this information age cannot be ignored; rather, it can be effectively utilized for educating a wider population base.

  2. Blanking Clearance and Punch Velocity Effects on The Sheared Edge Characteristic in Micro-Blanking of Commercially Pure Copper Sheet

    Directory of Open Access Journals (Sweden)

    Didin Zakaria Lubis

    2017-11-01

    Full Text Available This study aims to identify the influences between clearance and punch velocity on the part edge quality of blanked parts. Experiments have been conducted using material copper, punch-die clearance and punch velocity variations. In order to determine the reachable punch-die clearance and punch velocity required for blanking. The quality of the part-edge characteristics shows that higher punch velocity and decreases clearance value can improve the part-edge quality, resulting in smaller burr height and rollover, and a larger shear zone. Furthermore, it could be observed that the part-edge quality improvement when blanking with high punch velocity is much more distinct for stele than for copper. According to blanking theory, this improvement was expected because copper have much higher heat conduction coefficients. Therefore, the heat dissipates faster and the desired stress relief effect does not take place to the same degree as for stele.

  3. Harvest-related edge effects on prey availability and foraging of hooded warblers in a bottomland hardwood forest.

    Energy Technology Data Exchange (ETDEWEB)

    John Kilgo

    2005-04-20

    The effects of harvest-created canopy gaps in bottomland hardwood forests on arthropod abundance and, hence, the foraging ecology of birds are poorly understood. I predicted that arthropod abundance would be high near edges of group-selection harvest gaps and lower in the surrounding forest, and that male Hooded Warblers (Wilsonia citrina) foraging near gaps would find more prey per unit time than those foraging in the surrounding forest. In fact, arthropod abundance was greater >100 m from a gap edge than at 0-30 m or 30-100 m from an edge, due to their abundance on switchcane (Arundinaria gigantea); arthropods did not differ in abundance among distances from gaps on oaks (Quercus spp.) or red maple (Acer rubrum). Similarly, Hooded Warbler foraging attack rates were not higher near gap edges: when foraging for fledglings, attack rate did not differ among distances from gaps, but when foraging for themselves, attack rates actually were lower 0-30 m from gap edges than 30-100 m or >100 m from a gap edge. Foraging attack rate was positively associated with arthropod abundance. Hooded Warblers apparently encountered fewer prey and presumably foraged less efficiently where arthropods were least abundant, i.e., near gaps. That attack rates among birds foraging for fledglings were not affected by distance from gap (and hence arthropod abundance) suggests that prey availability may not be limiting at any location across the forest, despite the depressing effects of gaps on arthropod abundance.

  4. Natural vegetation cover in the landscape and edge effects: differential responses of insect orders in a fragmented forest.

    Science.gov (United States)

    González, Ezequiel; Salvo, Adriana; Valladares, Graciela

    2017-10-01

    Human activities have led to global simplification of ecosystems, among which Neotropical dry forests are some of the most threatened. Habitat loss as well as edge effects may affect insect communities. Here, we analyzed insects sampled with pan traps in 9 landscapes (at 5 scales, in 100-500 m diameter circles) comprising cultivated fields and Chaco Serrano forests, at overall community and taxonomic order level. In total 7043 specimens and 456 species of hexapods were captured, with abundance and richness being directly related to forest cover at 500 m and higher at edges in comparison with forest interior. Community composition also varied with forest cover and edge/interior location. Different responses were detected among the 8 dominant orders. Collembola, Hemiptera, and Orthoptera richness and/or abundance were positively related to forest cover at the larger scale, while Thysanoptera abundance increased with forest cover only at the edge. Hymenoptera abundance and richness were negatively related to forest cover at 100 m. Coleoptera, Diptera, and Hymenoptera were more diverse and abundant at the forest edge. The generally negative influence of forest loss on insect communities could have functional consequences for both natural and cultivated systems, and highlights the relevance of forest conservation. Higher diversity at the edges could result from the simultaneous presence of forest and matrix species, although "resource mapping" might be involved for orders that were richer and more abundant at edges. Adjacent crops could benefit from forest proximity since natural enemies and pollinators are well represented in the orders showing positive edge effects. © 2016 Institute of Zoology, Chinese Academy of Sciences.

  5. Atomistic study of drag, surface and inertial effects on edge dislocations in face-centered cubic metals

    International Nuclear Information System (INIS)

    Bitzek, Erik; Gumbsch, Peter

    2004-01-01

    Atomistic simulations of an accelerating edge dislocation were carried out to study the effects of drag and inertia. Using an embedded atom potential for nickel, the Peierls stress, the effective mass and the drag coefficient of an edge dislocation were determined for different temperatures and stresses in a simple slab geometry. The effect of {1 1 1} surfaces on an intersecting edge dislocation were studied by appropriately cutting the slab. A dislocation intersecting a surface step was used as a model system to demonstrate the importance of inertial effects for dynamically overcoming short range obstacles. Significant effects were found even at room temperature. A simple model based on the dislocation-obstacle interaction energies was used to describe the findings

  6. Dynamic anthropogenic edge effects on the distribution and diversity of fungi in fragmented old-growth forests.

    Science.gov (United States)

    Ruete, Alejandro; Snäll, Tord; Jönsson, Mari

    2016-07-01

    Diversity patterns and dynamics at forest edges are not well understood. We disentangle the relative importance of edge-effect variables on spatio-temporal patterns in species richness and occupancy of deadwood-dwelling fungi in fragmented old-growth forests. We related richness and log occupancy by 10 old-growth forest indicator fungi and by two common fungi to log conditions in natural and anthropogenic edge habitats of 31 old-growth Picea abies forest stands in central Sweden. We compared edge-to-interior gradients (100 m) to the forest interior (beyond 100 m), and we analyzed stand-level changes after 10 yr. Both richness and occupancy of logs by indicator species was negatively related to adjacent young clear-cut edges, but this effect decreased with increasing clear-cut age. The occupancy of logs by indicator species also increased with increasing distance to the natural edges. In contrast, the occupancy of logs by common species was positively related or unrelated to distance to clear-cut edges regardless of the edge age, and this was partly explained by fungal specificity to substrate quality. Stand-level mean richness and mean occupancy of logs did not change for indicator or common species over a decade. By illustrating the importance of spatial and temporal dimensions of edge effects, we extend the general understanding of the distribution and diversity of substrate-confined fungi in fragmented old-growth forests. Our results highlight the importance of longer forest rotation times adjacent to small protected areas and forest set-asides, where it may take more than 50 yr for indicator species richness levels to recover to occupancy levels observed in the forest interior. Also, non-simultaneous clear-cutting of surrounding productive forests in a way that reduces the edge effect over time (i.e., dynamic buffers) may increase the effective core area of small forest set-asides and improve their performance on protecting species of special concern for

  7. Effects of density gradients and fluctuations at the plasma edge on ECEI measurements at ASDEX Upgrade

    Science.gov (United States)

    Vanovac, B.; Wolfrum, E.; Denk, S. S.; Mink, F.; Laggner, F. M.; Birkenmeier, G.; Willensdorfer, M.; Viezzer, E.; Hoelzl, M.; Freethy, S. J.; Dunne, M. G.; Lessig, A.; Luhmann, N. C., Jr.; the ASDEX Upgrade Team; the EUROfusion MST1 Team

    2018-04-01

    Electron cyclotron emission imaging (ECEI) provides measurements of electron temperature (T e ) and its fluctuations (δT e ). However, when measuring at the plasma edge, in the steep gradient region, radiation transport effects must be taken into account. It is shown that due to these effects, the scrape-off layer region is not accessible to the ECEI measurements in steady state conditions and that the signal is dominated by the shine-through emission. Transient effects, such as filaments, can change the radiation transport locally, but cannot be distinguished from the shine-through. Local density measurements are essential for the correct interpretation of the electron cyclotron emission, since the density fluctuations influence the temperature measurements at the plasma edge. As an example, a low frequency 8 kHz mode, which causes 10%-15% fluctuations in the signal level of the ECEI, is analysed. The same mode has been measured with the lithium beam emission spectroscopy density diagnostic, and is very well correlated in time with high frequency magnetic fluctuations. With radiation transport modelling of the electron cyclotron radiation in the ECEI geometry, it is shown that the density contributes significantly to the radiation temperature (T rad) and the experimental observations have shown the amplitude modulation in both density and temperature measurements. The poloidal velocity of the low frequency mode measured by the ECEI is 3 km s-1. The calculated velocity of the high frequency mode measured with the magnetic pick-up coils is about 25 km s-1. Velocities are compared with the E × B background flow velocity and possible explanations for the origin of the low frequency mode are discussed.

  8. Use of Debye's series to determine the optimal edge-effect terms for computing the extinction efficiencies of spheroids.

    Science.gov (United States)

    Lin, Wushao; Bi, Lei; Liu, Dong; Zhang, Kejun

    2017-08-21

    The extinction efficiencies of atmospheric particles are essential to determining radiation attenuation and thus are fundamentally related to atmospheric radiative transfer. The extinction efficiencies can also be used to retrieve particle sizes or refractive indices through particle characterization techniques. This study first uses the Debye series to improve the accuracy of high-frequency extinction formulae for spheroids in the context of Complex angular momentum theory by determining an optimal number of edge-effect terms. We show that the optimal edge-effect terms can be accurately obtained by comparing the results from the approximate formula with their counterparts computed from the invariant imbedding Debye series and T-matrix methods. An invariant imbedding T-matrix method is employed for particles with strong absorption, in which case the extinction efficiency is equivalent to two plus the edge-effect efficiency. For weakly absorptive or non-absorptive particles, the T-matrix results contain the interference between the diffraction and higher-order transmitted rays. Therefore, the Debye series was used to compute the edge-effect efficiency by separating the interference from the transmission on the extinction efficiency. We found that the optimal number strongly depends on the refractive index and is relatively insensitive to the particle geometry and size parameter. By building a table of optimal numbers of edge-effect terms, we developed an efficient and accurate extinction simulator that has been fully tested for randomly oriented spheroids with various aspect ratios and a wide range of refractive indices.

  9. Conduction band edge effective mass of La-doped BaSnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    James Allen, S., E-mail: allen@itst.ucsb.edu; Law, Ka-Ming [Physics Department, University of California, Santa Barbara, California 93106-5100 (United States); Raghavan, Santosh; Schumann, Timo; Stemmer, Susanne [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)

    2016-06-20

    BaSnO{sub 3} has attracted attention as a promising material for applications requiring wide band gap, high electron mobility semiconductors, and moreover possesses the same perovskite crystal structure as many functional oxides. A key parameter for these applications and for the interpretation of its properties is the conduction band effective mass. We measure the plasma frequency of La-doped BaSnO{sub 3} thin films by glancing incidence, parallel-polarized resonant reflectivity. Using the known optical dielectric constant and measured electron density, the resonant frequency determines the band edge electron mass to be 0.19 ± 0.01. The results allow for testing band structure calculations and transport models.

  10. Effects of knife edge angle and speed on peak force and specific energy when cutting vegetables of diverse texture

    Directory of Open Access Journals (Sweden)

    Vishal Singh

    2016-04-01

    Full Text Available Cutting tool parameters such as edge-sharpness and speed of cut directly influence the shape of final samples and the required cutting force and specific energy for slicing or cutting operations. Cutting force and specific energy studies on different vegetables help to design the appropriate slicing or cutting devices. Peak cutting force and specific energy requirements for the transverse cutting of nine vegetables, differing in their textural characteristics of rind and flesh, were determined at cutting speeds of 20, 30, 40 mm min-1 and single-cut knife-edge angles of 15, 20 and 25° using a Universal Testing Machine. Low speed (20 mm min-1 cutting with a sharper knife-edge angle (15° required less peak force and specific energy than that of high-speed cutting (40 mm min-1 with a wider knife-edge angle (25°. The vegetables with the maximum and minimum variation in the average peak cutting force were aubergine, at 79.05 (for knife speed 20 mm min-1 and edge angle 150 to 285.1 N (40 mm min-1 and 250, and cucumber, at 11.61 (20 mm min-1 and 150 to 21.41 N (40 mm min-1 and 250, respectively. High speed (40 mm min-1, with a large knife-edge angle (25°, required the highest force and specific energy to cut the vegetables, however, low speed (20 mm min-1, with a small knife-edge angle (150, is preferred. Effects of cutting speed and knife-edge angle on peak force and specific energy responses were found significant (p<0.05. Linear or quadratic regressions gave a good fit of these variables. 

  11. Edge effects in four-point direct current potential drop measurements on metal plates

    International Nuclear Information System (INIS)

    Lu, Y; Bowler, N; Bowler, J R; Huang, Y

    2009-01-01

    Four-point direct current potential drop (DCPD) measurements are commonly used to measure the conductivity (or resistivity) of semiconductors and ferrous or non-ferrous metals. The measured electrical potential difference is often interpreted in terms of analytic expressions developed for large plates that are either 'thin' or 'thick' relative to the probe length. It is well known that the presence of the back surface of a plate leads to a solution expressed in terms of an infinite series representing the current source and its images. This approach can be generalized to account for multiple surfaces in order to obtain a solution for a finite plate, but convergence of the series is poor when the plate dimensions are similar to or smaller than the separation of the current injection and extraction points. Here, Fourier series representations of the infinite sums are obtained. It is shown that the Fourier series converge with many fewer terms than the series obtained from image theory, for plates with dimensions similar to or smaller than the separation of the current injection and extraction points. Comparing calculated results for the potential drop obtained by a four-point probe centred on finite plates of varying dimension, with those for a probe in contact with a large (laterally infinite) plate, estimates are given of the uncertainty due to edge effects in measurements on small plates interpreted using analytic formulae developed for large plates. It is also shown that these uncertainties due to edge effects are reduced, for a given plate size, if the probe pick-up points are moved closer to the current injection points, rather than adopting the common arrangement in which the four probe points are equally spaced. Calculated values of DCPD are compared with experimental data taken on aluminium and spring-steel plates of various sizes and excellent agreement is obtained.

  12. Edge effects in four-point direct current potential drop measurements on metal plates

    Science.gov (United States)

    Lu, Y.; Bowler, N.; Bowler, J. R.; Huang, Y.

    2009-07-01

    Four-point direct current potential drop (DCPD) measurements are commonly used to measure the conductivity (or resistivity) of semiconductors and ferrous or non-ferrous metals. The measured electrical potential difference is often interpreted in terms of analytic expressions developed for large plates that are either 'thin' or 'thick' relative to the probe length. It is well known that the presence of the back surface of a plate leads to a solution expressed in terms of an infinite series representing the current source and its images. This approach can be generalized to account for multiple surfaces in order to obtain a solution for a finite plate, but convergence of the series is poor when the plate dimensions are similar to or smaller than the separation of the current injection and extraction points. Here, Fourier series representations of the infinite sums are obtained. It is shown that the Fourier series converge with many fewer terms than the series obtained from image theory, for plates with dimensions similar to or smaller than the separation of the current injection and extraction points. Comparing calculated results for the potential drop obtained by a four-point probe centred on finite plates of varying dimension, with those for a probe in contact with a large (laterally infinite) plate, estimates are given of the uncertainty due to edge effects in measurements on small plates interpreted using analytic formulae developed for large plates. It is also shown that these uncertainties due to edge effects are reduced, for a given plate size, if the probe pick-up points are moved closer to the current injection points, rather than adopting the common arrangement in which the four probe points are equally spaced. Calculated values of DCPD are compared with experimental data taken on aluminium and spring-steel plates of various sizes and excellent agreement is obtained.

  13. The Effects of Vegetative Type, Edges, Fire History, Rainfall and Management in Fire-Maintained Ecosystems

    Science.gov (United States)

    Breininger, David R.; Foster, Tammy E.; Carter, Geoffrey M.; Duncan, Brean W.; Stolen, Eric D.; Lyon, James E.

    2017-01-01

    The combined effects of repeated fires, climate, and landscape features (e.g., edges) need greater focus in fire ecology studies, which usually emphasize characteristics of the most recent fire and not fire history. Florida scrub-jays are an imperiled, territorial species that prefer medium (1.2-1.7 m) shrub heights. We measured short, medium, and tall habitat quality states annually within 10 ha grid cells that represented potential territories because frequent fires and vegetative recovery cause annual variation in habitat quality. We used multistate models and model selection to test competing hypotheses about how transition probabilities between states varied annually as functions of environmental covariates. Covariates included vegetative type, edges, precipitation, openings (gaps between shrubs), mechanical cutting, and fire characteristics. Fire characteristics not only included an annual presenceabsence of fire covariate, but also fire history covariates: time since the previous fire, the maximum fire-free interval, and the number of repeated fires. Statistical models with support included many covariates for each transition probability, often including fire history, interactions and nonlinear relationships. Tall territories resulted from 28 years of fire suppression and habitat fragmentation that reduced the spread of fires across landscapes. Despite 35 years of habitat restoration and prescribed fires, half the territories remained tall suggesting a regime shift to a less desirable habitat condition. Measuring territory quality states and environmental covariates each year combined with multistate modeling provided a useful empirical approach to quantify the effects of repeated fire in combinations with environmental variables on transition probabilities that drive management strategies and ecosystem change.

  14. Living edge

    DEFF Research Database (Denmark)

    Earon, Ofri

    2014-01-01

    was originally introduced to enhance indoor qualities including light and view. Throughout the paper, it is argued that these ecological motives have grown to architectural and urban dimensions. The paper analyzes the characteristics and potentials of these dimensions and their interconnections. The paper...... on the ground level, but there is a lack of recognition in the significance of communicative characters as well at the higher part of the edge. The city’s planning approach is “Consider urban life before urban space. Consider urban space before buildings” This urban strategy neglects the possible architectural...... contribution to the street atmosphere and its effect on urban life. Bay balcony has been a common architectural element in Copenhagen’s residential buildings, since the end of the twenties. It is a domestic border with an architectural thickness combining window, door, windowsill and balcony. The bay balcony...

  15. Detection alpha particles and Cf-252 fission fragments with track solid detectors and with surface barrier detectors: efficiency determination

    International Nuclear Information System (INIS)

    Khouri, M.T.F.C.; Koskinas, M.F.; Andrade, C. de; Vilela, E.C.; Hinostroza, H.; Kaschiny, J.R.A.; Costa, M.S. da; Rizzo, P.; Santos, W.M.S.

    1990-01-01

    The technique of particle detection by solid track detectors, types of developing and analysis of results are presented. Efficiency measurements of alpha particle detection with Makrofol e and surface barrier detector are made. Detection of Cf-252 fission fragments is shown. (L.C.)

  16. Detection of alpha particles and Cf-252 fission fragments with solid track detectors and surface barrier detector. Efficiency calculation

    International Nuclear Information System (INIS)

    Khouri, M.T.F.C.; Koskinas, M.F.; Andrade, C. de; Vilela, E.C.; Hinostroza, H.; Kaschiny, J.E.A.; Costa, M.S. da; Rizzo, P.; Santos, W.M.S.

    1990-01-01

    A technique for particle detection by using track solid detector and also types of revealing and result analysis are presented concerned to Cf-252 fission fragments detection. Measurements of alpha particles detection efficiency using Makrofol E and surface barrier detector are performed. (L.C.J.A.)

  17. Wild pigs (Sus scrofa) mediate large-scale edge effects in a lowland tropical rainforest in Peninsular Malaysia.

    Science.gov (United States)

    Fujinuma, Junichi; Harrison, Rhett D

    2012-01-01

    Edge-effects greatly extend the area of tropical forests degraded through human activities. At Pasoh, Peninsular Malaysia, it has been suggested that soil disturbance by highly abundant wild pigs (Sus scrofa), which feed in adjacent Oil Palm plantations, may have mediated the invasion of Clidemia hirta (Melastomataceae) into the diverse tropical lowland rain forest. To investigate this hypothesis, we established three 1 km transects from the forest/Oil Palm plantation boundary into the forest interior. We recorded the distribution of soil disturbance by wild pigs, C. hirta abundance, and environmental variables. These data were analyzed using a hierarchical Bayesian model that incorporated spatial auto-correlation in the environmental variables. As predicted, soil disturbance by wild pigs declined with distance from forest edge and C. hirta abundance was correlated with the level of soil disturbance. Importantly there was no effect of distance on C. hirta abundance, after controlling for the effect of soil disturbance. Clidemia hirta abundance was also correlated with the presence of canopy openings, but there was no significant association between the occurrence of canopy openings and distance from the edge. Increased levels of soil disturbance and C. hirta abundance were still detectable approximately 1 km from the edge, demonstrating the potential for exceptionally large-scale animal mediated edge effects.

  18. An edge pedestal model

    International Nuclear Information System (INIS)

    Stacev, W.M.

    2001-01-01

    A new model for calculation of the gradient scale lengths in the edge pedestal region and of the edge transport barrier width in H-mode tokamak plasmas will be described. Model problem calculations which demonstrate the promise of this model for predicting experimental pedestal properties will be discussed. The density and Prague gradient scale lengths (L) in the edge are calculated from the particle and ion and electron energy radial transport equations, making use of (presumed) known particle and energy fluxes flowing across the edge transport barrier from the core into the SOL and of edge transport coefficients. The average values of the particle and heat fluxes in the edge transport barrier are calculated in terms of the fluxes crossing into the SOL and the atomic physics reaction rates (ionisation, charge-exchange, elastic scattering, impurity radiation) in the edge by integrating the respective transport equations from the pedestal to the separatrix. An important implication of this model is that the pedestal gradient scale lengths depend not just on local pedestal platers properties but also on particle and energy fluxes from the core plasma and on recycling neutral fluxes that penetrate into the plasma edge, both of which in turn depend on the pedestal properties. The MHD edge pressure gradient constraint α≤ α C is used to determine the pressure width of the edge transport barrier, Δ TB = Δ TB (α c ). Three different models for the MHD edge pressure gradient constraint have been investigated: (1) nominal ideal ballooning mode theory, (2) ballooning mode theory taking into account the edge geometry and shear to access He second stability region; and pedestal β-limit theory when the ballooning modes are stabilised by diamagnetic effects. A series of calculations have been made for a DIII-D model problem. The calculated gradient scale lengths and edge transport barrier widths are of the magnitude of values observed experimentally, and certain trends

  19. Electric field strength and plasma delay in silicon surface barrier detector

    International Nuclear Information System (INIS)

    Kanno, I.; Inbe, T.; Kanazawa, S.; Kimura, I.

    1994-01-01

    The resistivity change of a silicon irradiated by high energy neutrons became an interest of study associated with the large scale accelerator projects . The increase of the resistivity of the silicon of a silicon surface barrier detector (SSBD) was studied as a function of neutron fluence. The plasma delay, which was an interesting but not favorite timing property of the SSBD, was reported being dependent on the resistivity of silicon . The neutron irradiation brings the change of timing property as well as the resistivity change on the SSBD. The resistivity dependence of the plasma delay should be studied for the purpose of high energy accelerator experiments. Some empirical formulae of the plasma delay were reported, however, there were no discussions on the physical meanings of the resistivity dependence of the plasma delay. The plasma delay in a SSBD is discussed in the light of electric field strength in the depletion layer of the SSBD. The explanation of the plasma delay is presented taking into account of the competing two electric forces. The resistivity of the silicon affects the plasma delay through the electric forces. 3 figs, 3 refs. (author)

  20. Hanford Site Permanent Isolation Surface Barrier Development Program: Fiscal year 1992 and 1993 highlights

    International Nuclear Information System (INIS)

    Cadwell, L.L.; Link, S.O.; Gee, G.W.

    1993-09-01

    The Hanford Site Permanent Isolation Surface Barrier Development Program was jointly developed by the Pacific Northwest Laboratory and Westinghouse Hanford Company to design and test an earthen cover system that can be used to inhibit water infiltration; plant, animal, and human intrusion; and wind and water erosion. Kaiser Engineers Hanford Company provided engineering design support for the program. Work on barrier design has been under way at Hanford for nearly 10 years. The comprehensive development of a long-term barrier, formerly the Hanford Site Protective Barrier Development Program, was initiated in FY 1986, and a general field-tested design is expected to be completed by FY 1998. Highlights of efforts in FY 1992 and FY 1993 included the resumption of field testing, the completion of the prototype barrier design, and the convening of an external peer review panel, which met twice with the barrier development team. The review panel provided helpful guidance on current and future barrier development activities, while commending the program for its significant technical contributions to innovative barrier technology development

  1. Pulse-height response of silicon surface-barrier detectors to high-energy heavy ions

    International Nuclear Information System (INIS)

    Smith, G.D.

    1973-01-01

    The pulse-height defect (PHD) of high-energy heavy ions in silicon surface-barrier detectors can be divided into three components: (1) energy loss in the gold-surface layer, (2) a nuclear-stopping defect, and (3) a defect due to recombination of electron-hole pairs in the plasma created by the heavy ion. The plasma recombination portion of the PHD was the subject of this study using the variation of the PHD with (1) the angle of incidence of incoming heavy ions, and (2) changes in the detector bias. The Tandem Van de Graaff accelerator at Argonne National Laboratory was used to produce scattered beam ions ( 32 S, 35 Cl) and heavy target recoils (Ni, Cu, 98 Mo, Ag, Au) at sufficient energies to produce a significant recombination defect. The results confirm the existence of a recombination zone at the front surface of these detectors and the significance of plasma recombination as a portion of the pulse-height defect. (Diss. Abstr. Int., B)

  2. Project and construction of a spectrometer for alpha particles using surface barrier detectors

    International Nuclear Information System (INIS)

    Terini, R.A.

    1986-01-01

    The project, construction, tests and some applications of a system for alpha and beta spectrometry, using surface barrier detector are described. The device includes a solid state detector ORTEC-Series F coupled to a system for amplifying the charges produced by passage of an ionizing particle through the detector. The amplifying system is composed by a charge sensitive pre-amplifier, which employs an operational amplifier CA 3140, and a low noise linear amplifier, which is based on the operational amplifiers CA 3140 and LM 301. The pre-amplifier stage input impedance is on the order of TΩ and produces output pulses which heights are proportional to total charge produced by passage of particle through the detector sensitive volume. The main advantage to use charge sensitive system lies in obtention of independent pulse heights of the distributed capacity of connecting cable between the detector and the pre-amplifier. The total system amplification ca reach a maximum of 50.000 in the linear region. Pulses are analysed in a multichannel system ORTEC, model 6240. The amplifier system is easily constructed and low cost using components available in the national market, and it can be employed with ionization chambers, proportional counters, scitillation counters and semiconductor detectors. The results of spectrometer application for alpha spectrometry of AM 241 source were compared to systems made with imported stages. (Author) [pt

  3. Effect of Hardwood Sawmill Edging and Trimming Practices on Furniture Part Production

    Science.gov (United States)

    D. Earl Kline; Carmen Regalado; Eugene M. Wengert; Fred M. Lamb; Philip A. Araman

    1993-01-01

    In a recent edging and trimming study at three hardwood sawmills, it was observed that the lumber volume produced was approximately 10 percent less than would be necessary to make the most valuable lumber. Furthermore, the excess portion of wood that was removed from the edging and trimming process contained a large percentage of clear wood. In light of rising costs...

  4. Effects of edge contrast on redback salamander distribution in even-aged northern hardwoods

    Science.gov (United States)

    Richard M. DeGraaf; Mariko. Yamasaki

    2002-01-01

    Terrestrial salamanders are sensitive to forest disturbance associated with even-aged management. We studied the distribution of redback salamanders (Plethodon cinereus) for 4 yr at edges between even-aged northern hardwood stands along three replicate transects in each of three edge contrast types: regeneration/mature, sapling/mature, and...

  5. Edge effects at an induced forest-grassland boundary: forest birds in ...

    African Journals Online (AJOL)

    Bird species diversity and guild composition between the edge (5-10 m from the margin) of primary forest abutting grassland and the deep interior (> 500 m from the margin) in the Dngoye Forest Reserve were compared. Edge and interior sites were chosen that were homogeneous with respect to habitat physiognomy i.e. ...

  6. The effect of edge interlaminar stresses on the strength of carbon/epoxy laminates of different stacking geometry

    OpenAIRE

    MOMCILO STEVANOVIC; MILAN GORDIC; DANIELA SEKULIC; ISIDOR DJORDJEVIC

    2006-01-01

    The effect of edge interlaminar stresses on strength of carbon/epoxy laminates of different stacking geometry: cross-ply, quasi-isotropic and angle-ply laminates with additional 0º and 90º ply was studied. Coupons with two widths of laminates with an inverse stacking sequence were tested in static tensile tests. The effect of edge interlaminar stresses on strength was studied, by comparing the values of the tensile strength of laminate coupons of the same width with an inverse stacking sequen...

  7. Edge-defect induced spin-dependent Seebeck effect and spin figure of merit in graphene nanoribbons.

    Science.gov (United States)

    Liu, Qing-Bo; Wu, Dan-Dan; Fu, Hua-Hua

    2017-10-11

    By using the first-principle calculations combined with the non-equilibrium Green's function approach, we have studied spin caloritronic properties of graphene nanoribbons (GNRs) with different edge defects. The theoretical results show that the edge-defected GNRs with sawtooth shapes can exhibit spin-dependent currents with opposite flowing directions by applying temperature gradients, indicating the occurrence of the spin-dependent Seebeck effect (SDSE). The edge defects bring about two opposite effects on the thermal spin currents: the enhancement of the symmetry of thermal spin-dependent currents, which contributes to the realization of pure thermal spin currents, and the decreasing of the spin thermoelectric conversion efficiency of the devices. It is fortunate that applying a gate voltage is an efficient route to optimize these two opposite spin thermoelectric properties towards realistic device applications. Moreover, due to the existence of spin-splitting band gaps, the edge-defected GNRs can be designed as spin-dependent Seebeck diodes and rectifiers, indicating that the edge-defected GNRs are potential candidates for room-temperature spin caloritronic devices.

  8. Effects of a sheared toroidal rotation on the stability boundary of the MHD modes in the tokamak edge pedestal

    International Nuclear Information System (INIS)

    Aiba, N.; Tokuda, S.; Oyama, N.; Ozeki, T.; Furukawa, M.

    2009-01-01

    Effects of a sheared toroidal rotation are investigated numerically on the stability of the MHD modes in the tokamak edge pedestal, which relate to the type-I edge-localized mode. A linear MHD stability code MINERVA is newly developed for solving the Frieman-Rotenberg equation that is the linear ideal MHD equation with flow. Numerical stability analyses with this code reveal that the sheared toroidal rotation destabilizes edge localized MHD modes for rotation frequencies which are experimentally achievable, though the ballooning mode stability changes little by rotation. This rotation effect on the edge MHD stability becomes stronger as the toroidal mode number of the unstable MHD mode increases when the stability analysis was performed for MHD modes with toroidal mode numbers smaller than 40. The toroidal mode number of the unstable MHD mode depends on the stabilization of the current-driven mode and the ballooning mode by increasing the safety factor. This dependence of the toroidal mode number of the unstable mode on the safety factor is considered to be the reason that the destabilization by toroidal rotation is stronger for smaller edge safety factors.

  9. Analytical model based on cohesive energy to indicate the edge and corner effects on melting temperature of metallic nanoparticles

    International Nuclear Information System (INIS)

    Shidpour, Reza; Hamid, Delavari H.; Vossoughi, M.

    2010-01-01

    Graphical abstract: The effect of edge and corner atoms of nanoparticle (solid line) cause melting temperature drops more compared to considering them as same as only surface atoms (dash line). This reduction is significant especially when the size of nanoparticle is below 10 nm. - Abstract: An analytical model based on cohesive energy has been conducted to study the effects of edge, corner, and inward surface relaxation as varying parameters on melting temperature of nanoparticles. It is shown that taking into account the edge and corner (EC) atoms of nanoparticle, causes to drop melting temperature more, when compared to consider them the same as only surface atoms. This reduction is significant especially when the size of nanoparticle is below 10 nm. The results are supported by available experimental results of tin, lead and gold melting temperature (T m ). Finally, it is shown that inward relaxation increases melting temperature slightly.

  10. Non-linear effects in transition edge sensors for X-ray detection

    International Nuclear Information System (INIS)

    Bandler, S.R.; Figueroa-Feliciano, E.; Iyomoto, N.; Kelley, R.L.; Kilbourne, C.A.; Murphy, K.D.; Porter, F.S.; Saab, T.; Sadleir, J.

    2006-01-01

    In a microcalorimeter that uses a transition-edge sensor to detect energy depositions, the small signal energy resolution improves with decreasing heat capacity. This improvement remains true up to the point where non-linear and saturation effects become significant. This happens when the energy deposition causes a significant change in the sensor resistance. Not only does the signal size become a non-linear function of the energy deposited, but also the noise becomes non-stationary over the duration of the pulse. Algorithms have been developed that can calculate the optimal performance given this non-linear behavior that typically requires significant processing and calibration work-both of which are impractical for space missions. We have investigated the relative importance of the various non-linear effects, with the hope that a computationally simple transformation can overcome the largest of the non-linear and non-stationary effects, producing a highly linear 'gain' for pulse-height versus energy, and close to the best energy resolution at all energies when using a Wiener filter

  11. Edge loading has a paradoxical effect on wear in metal-on-polyethylene total hip arthroplasties.

    Science.gov (United States)

    Harris, William H

    2012-11-01

    Edge wear is an adverse factor that can negatively impact certain THAs. In some metal-on-metal THAs, it can lead to adverse tissue reactions including aseptic lymphocytic vasculitis-associated lesions and even to pseudotumor formation. In some ceramic-on-ceramic THAs, it can lead to squeaking and/or stripe wear. Edge wear in metal-on-metal and ceramic-on-ceramic THAs can also be associated with accelerated wear across the articulation of these joints. I asked: Does edge wear occur in metal-on-polyethylene (MOP) articulations? And if so, does it increase joint wear? I examined the evidence in the literature for edge wear occurring in MOP THA and then assessed the evidence in the literature for data supporting the concept that edge wear in MOP hips could accelerate wear across the articulation over time. Extensive data in the literature confirm edge wear is common in MOP THA. Surprisingly, the evidence does not support that it accelerates wear across the articulation. In fact, substantial data support the concept that it does not. These observations suggest, in terms of edge wear accelerating overall wear, MOP articulation may have a privileged position compared to hard-on-hard THA articulations.

  12. Effects of Cutting Edge Microgeometry on Residual Stress in Orthogonal Cutting of Inconel 718 by FEM.

    Science.gov (United States)

    Shen, Qi; Liu, Zhanqiang; Hua, Yang; Zhao, Jinfu; Lv, Woyun; Mohsan, Aziz Ul Hassan

    2018-06-14

    Service performance of components such as fatigue life are dramatically influenced by the machined surface and subsurface residual stresses. This paper aims at achieving a better understanding of the influence of cutting edge microgeometry on machined surface residual stresses during orthogonal dry cutting of Inconel 718. Numerical and experimental investigations have been conducted in this research. The cutting edge microgeometry factors of average cutting edge radius S¯, form-factor K , and chamfer were investigated. An increasing trend for the magnitudes of both tensile and compressive residual stresses was observed by using larger S¯ or introducing a chamfer on the cutting edges. The ploughing depth has been predicted based on the stagnation zone. The increase of ploughing depth means that more material was ironed on the workpiece subsurface, which resulted in an increase in the compressive residual stress. The thermal loads were leading factors that affected the surface tensile residual stress. For the unsymmetrical honed cutting edge with K = 2, the friction between tool and workpiece and tensile residual stress tended to be high, while for the unsymmetrical honed cutting edge with K = 0.5, the high ploughing depth led to a higher compressive residual stress. This paper provides guidance for regulating machine-induced residual stress by edge preparation.

  13. Breeding Guild Determines Frog Distributions in Response to Edge Effects and Habitat Conversion in the Brazil's Atlantic Forest.

    Directory of Open Access Journals (Sweden)

    Rodrigo B Ferreira

    Full Text Available Understanding the response of species with differing life-history traits to habitat edges and habitat conversion helps predict their likelihood of persistence across changing landscape. In Brazil's Atlantic Forest, we evaluated frog richness and abundance by breeding guild at four distances from the edge of a reserve: i 200 m inside the forest, ii 50 m inside the forest, iii at the forest edge, and iv 50 m inside three different converted habitats (coffee plantation, non-native Eucalyptus plantation, and abandoned pastures, hereafter matrix types. By sampling a dry and a wet season, we recorded 622 individual frogs representing 29 species, of which three were undescribed. Breeding guild (i.e. bromeliad, leaf-litter, and water-body breeders was the most important variable explaining frog distributions in relation to edge effects and matrix types. Leaf-litter and bromeliad breeders decreased in richness and abundance from the forest interior toward the matrix habitats. Water-body breeders increased in richness toward the matrix and remained relatively stable in abundance across distances. Number of large trees (i.e. DBH > 15 cm and bromeliads best explained frog richness and abundance across distances. Twenty species found in the interior of the forest were not found in any matrix habitat. Richness and abundance across breeding guilds were higher in the rainy season but frog distributions were similar across the four distances in the two seasons. Across matrix types, leaf-litter species primarily used Eucalyptus plantations, whereas water-body species primarily used coffee plantations. Bromeliad breeders were not found inside any matrix habitat. Our study highlights the importance of primary forest for bromeliad and leaf-litter breeders. We propose that water-body breeders use edge and matrix habitats to reach breeding habitats along the valleys. Including life-history characteristics, such as breeding guild, can improve predictions of frog

  14. Breeding Guild Determines Frog Distributions in Response to Edge Effects and Habitat Conversion in the Brazil's Atlantic Forest.

    Science.gov (United States)

    Ferreira, Rodrigo B; Beard, Karen H; Crump, Martha L

    2016-01-01

    Understanding the response of species with differing life-history traits to habitat edges and habitat conversion helps predict their likelihood of persistence across changing landscape. In Brazil's Atlantic Forest, we evaluated frog richness and abundance by breeding guild at four distances from the edge of a reserve: i) 200 m inside the forest, ii) 50 m inside the forest, iii) at the forest edge, and iv) 50 m inside three different converted habitats (coffee plantation, non-native Eucalyptus plantation, and abandoned pastures, hereafter matrix types). By sampling a dry and a wet season, we recorded 622 individual frogs representing 29 species, of which three were undescribed. Breeding guild (i.e. bromeliad, leaf-litter, and water-body breeders) was the most important variable explaining frog distributions in relation to edge effects and matrix types. Leaf-litter and bromeliad breeders decreased in richness and abundance from the forest interior toward the matrix habitats. Water-body breeders increased in richness toward the matrix and remained relatively stable in abundance across distances. Number of large trees (i.e. DBH > 15 cm) and bromeliads best explained frog richness and abundance across distances. Twenty species found in the interior of the forest were not found in any matrix habitat. Richness and abundance across breeding guilds were higher in the rainy season but frog distributions were similar across the four distances in the two seasons. Across matrix types, leaf-litter species primarily used Eucalyptus plantations, whereas water-body species primarily used coffee plantations. Bromeliad breeders were not found inside any matrix habitat. Our study highlights the importance of primary forest for bromeliad and leaf-litter breeders. We propose that water-body breeders use edge and matrix habitats to reach breeding habitats along the valleys. Including life-history characteristics, such as breeding guild, can improve predictions of frog distributions in

  15. A statistical investigation of the effects of edge localized modes on the equilibrium reconstruction in JET

    International Nuclear Information System (INIS)

    Murari, A; Peluso, E; Gaudio, P; Gelfusa, M; Maviglia, F; Hawkes, N

    2012-01-01

    The configuration of magnetic fields is an essential ingredient of tokamak physics. In modern day devices, the magnetic topology is normally derived from equilibrium codes, which solve the Grad–Shafranov equation with constraints imposed by the available measurements. On JET, the main code used for this purpose is EFIT and the more commonly used diagnostics are external pick-up coils. Both the code and the measurements present worse performance during edge localized modes (ELMs). To quantify this aspect, various statistical indicators, based on the values of the residuals and their probability distribution, are defined and calculated. They all show that the quality of EFIT reconstructions is clearly better in the absence of ELMs. To investigate the possible causes of the detrimental effects of ELMs on the reconstruction, the pick-up coils are characterized individually and both the spatial distribution and time behaviour of their residuals are analysed in detail. The coils with a faster time response are the ones reproduced less well by EFIT. The constraints of current and pressure at the separatrix are also varied but the effects of such modifications do not result in decisive improvements in the quality of the reconstructions. The interpretation of this experimental evidence is not absolutely compelling but strongly indicative of deficiencies in the physics model on which the JET reconstruction code is based. (paper)

  16. Solute effects on edge dislocation pinning in complex alpha-Fe alloys

    Science.gov (United States)

    Pascuet, M. I.; Martínez, E.; Monnet, G.; Malerba, L.

    2017-10-01

    Reactor pressure vessel steels are well-known to harden and embrittle under neutron irradiation, mainly because of the formation of obstacles to the motion of dislocations, in particular, precipitates and clusters composed of Cu, Ni, Mn, Si and P. In this paper, we employ two complementary atomistic modelling techniques to study the heterogeneous precipitation and segregation of these elements and their effects on the edge dislocations in BCC iron. We use a special and highly computationally efficient Monte Carlo algorithm in a constrained semi-grand canonical ensemble to compute the equilibrium configurations for solute clusters around the dislocation core. Next, we use standard molecular dynamics to predict and analyze the effect of this segregation on the dislocation mobility. Consistently with expectations our results confirm that the required stress for dislocation unpinning from the precipitates formed on top of it is quite large. The identification of the precipitate resistance allows a quantitative treatment of atomistic results, enabling scale transition towards larger scale simulations, such as dislocation dynamics or phase field.

  17. Curvature Effects on the Vibration Characteristics of Doubly Curved Shallow Shells with General Elastic Edge Restraints

    Directory of Open Access Journals (Sweden)

    Hui Shi

    2015-01-01

    Full Text Available Effects of curvature upon the vibration characteristics of doubly curved shallow shells are assessed in this paper. Boundary conditions of the shell are generally specified in terms of distributed elastic restraints along the edges. The classical homogeneous boundary supports can be easily simulated by setting the stiffnesses of restraining springs to either zero or infinite. Vibration problems of the shell are solved by a modified Fourier series method that each of the displacements is invariably expressed as a simple trigonometric series which converges uniformly and acceleratedly over the solution domain. All the unknown expansion coefficients are treated equally as a set of independent generalized coordinates and solved using the Rayleigh-Ritz technique. The current method provides a unified solution to the vibration problems of curved shallow shells involving different geometric properties and boundary conditions with no need of modifying the formulations and solution procedures. Extensive tabular and graphical results are presented to show the curvature effects on the natural frequencies of the shell with various boundary conditions.

  18. Soil and fertilizer amendments and edge effects on the floral succession of pulverized fuel ash

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, P. [Roehampton University, London (United Kingdom). Whitelands College

    2009-01-15

    Plots of fresh pulverized fuel ash (PFA, an industrial waste) were inoculated with soils from existing PFA sites and fertilizers in a factorial design, then left unmanaged for 12 years during which time the floral development and soil chemistry were monitored annually. For the first 3 years, the site supported a sparse mix of chenopods (including the scarce Chenopodium glaucum) and halophytes. As salinity declined, ruderals, legumes, and grasses plus the fire-site moss Funaria hygrometrica colonized, followed by Festuca arundinacea grassland (NVC community MG12) and Hippophae rhamnoides scrub. Dactylorhiza incarnata (orchidacea) appeared after 7 years, but only in plots that had received soil from existing orchid colonies. Four years later, a larger second generation of Dactylorhiza appeared, but only in the central zone of the site where vegetation was thinnest. By year 12, the site was dominated by coarse grasses and scrub, with early successional species persisting only in the sparsely vegetated center, where nitrate levels were lowest. This edge effect is interpreted as centripetal encroachment, a process of potentially wider concern for the conservation of low-fertility habitat patches. Overall, seed bank inoculation seems to have introduced few but desirable species (D. incarnata, Pyrola rotundifolia, some halophytes, and annuals), whereas initial application of organic fertilizer had long-lasting ({ge} 10 years) effects on cover and soil composition.

  19. Performance of a Surface Barrier for Waste Isolation and Flux Reduction at the Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z. F.; Wellman, Dawn M.; Morse, John G.; Leary, Kevin D.; Freshley, Mark D.

    2016-05-13

    Based on the knowledge gained from a decade of laboratory, field, and numerical studies, the Prototype Hanford Barrier (PHB) was designed and constructed between late 1993 and late 1994 over the 216-B-57 Crib in the 200-BP-1 Operable Unit at the Hanford Site. The PHB has been monitored since 1994 to evaluate the physical, hydrologic, and ecological performance. Two stress tests were carried out in the past: (1) an enhanced (about 3 times the multi-year average of 160 mm/year) precipitation test from water year (WY) 1995 to WY1997, which included a man-made 1000-year return 24-hour rainstorms in March each year, and (2) a controlled fire test in 2008. The purpose of this article is to present the main findings of the PHB demonstration since 1994. From 1994 to present, the PHB has limited drainage of less than 0.2 mm yr-1, which is below the 0.5 mm yr-1 design goal, and minimized erosion. The observations suggest the PHB is robust enough to endure the hydrological stress of three times average precipitation and 1000-year return 24-hour rainstorms. After the controlled fire, far less vegetation grows and grasses are the dominant vegetation (compared to shrubs on the unburned section). Even so, the grasses can remove nearly all the stored water in the burned section, although during a longer period of time than in the unburned section. The findings at the PHB are useful for the design and monitoring of future surface barriers at Hanford and elsewhere.

  20. Effects of higher-coordination shells in garnets detected by XAS at the Al K-edge

    International Nuclear Information System (INIS)

    Marcelli, A.; Wu, Z.; Mottana, A.; Giuli, G.; Paris, E.; Seifert, F.

    1996-03-01

    The aluminium 1 s x-ray-absorption spectra of a series of garnets, pyrope, almandine, spessartine and grossular, are compared to full multiple-scattering calculation using cluster models. An overall good agreement between experiment and calculation, extended also to the edge region,is obtained in the energy range in up to 60 e V above the threshold, provided cluster containing at least 40 atoms are used. The analysis of these garnet XAS spectra provides clear evidence on the effect of probe, XANES spectroscopy at the edge of low Z elements appears to be a perfect tool to investigate the role played by atoms located in higher-coordination shells

  1. Effects of higher-coordination shells in garnets detected by XAS at the Al K-edge

    Energy Technology Data Exchange (ETDEWEB)

    Marcelli, A. [Istituto Nazionale di Fisica Nucleare, Frascati (Italy). Lab. Nazionale di Frascati; Wu, Z. [CNRS UMR 110, Laboratoire de Chimie des Solides, Nantes Cedex (France). Institut de materiaux de Nantes; Mottana, A. [Roma III Univ., Rome (Italy). Dipartimento di Scienze Geologiche; Giuli, G.; Paris, E. [Camerino Univ., Camerino (Italy).Diparimento di Scienze della Terra; Seifert, F [Univ. Bayreuth, Bayreuth (Italy). Bayerisches Geoinstitut (Germany)

    1996-03-01

    The aluminium 1 s x-ray-absorption spectra of a series of garnets, pyrope, almandine, spessartine and grossular, are compared to full multiple-scattering calculation using cluster models. An overall good agreement between experiment and calculation, extended also to the edge region,is obtained in the energy range in up to 60 e V above the threshold, provided cluster containing at least 40 atoms are used. The analysis of these garnet XAS spectra provides clear evidence on the effect of probe, XANES spectroscopy at the edge of low Z elements appears to be a perfect tool to investigate the role played by atoms located in higher-coordination shells.

  2. Study of edge effects in the breakdown process of p sup + on n-bulk silicon diodes

    CERN Document Server

    Militaru, O; Bozzi, C; Rold, M D; Dell'Orso, R; Dutta, S; Messineo, A; Mihul, A; Tonelli, G; Verdini, P G; Wheadon, R; Xie, Z

    2000-01-01

    The paper describes the role of the n sup + edge implants in the breakdown process of p sup + on n-bulk silicon diodes. Laboratory measurements and simulation studies are presented on a series of test structures aimed at an optimization of the design in the edge region. The dependence of the breakdown voltage on the geometrical parameters of the devices is discussed in detail. Design rules are extracted for the use of n sup + -layers along the scribe line to avoid surface conduction of current generated by the exposed edges. The effect of neutron irradiation has been studied up to a fluence of 1.8x10 sup 1 sup 5 cm sup - sup 2.

  3. Effects of Leading Edge Defect on the Aerodynamic and Flow Characteristics of an S809 Airfoil.

    Science.gov (United States)

    Wang, Yan; Zheng, Xiaojing; Hu, Ruifeng; Wang, Ping

    Unexpected performance degradation occurs in wind turbine blades due to leading edge defect when suffering from continuous impacts with rain drops, hails, insects, or solid particles during its operation life. To assess this issue, this paper numerically investigates the steady and dynamic stall characteristics of an S809 airfoil with various leading edge defects. More leading edge defect sizes and much closer to practical parameters are investigated in the paper. Numerical computation is conducted using the SST k-ω turbulence model, and the method has been validated by comparison with existed published data. In order to ensure the calculation convergence, the residuals for the continuity equation are set to be less than 10-7 and 10-6 in steady state and dynamic stall cases. The simulations are conducted with the software ANSYS Fluent 13.0. It is found that the characteristics of aerodynamic coefficients and flow fields are sensitive to leading edge defect both in steady and dynamic conditions. For airfoils with the defect thickness of 6%tc, leading edge defect has a relative small influence on the aerodynamics of S809 airfoil. For other investigated defect thicknesses, leading edge defect has much greater influence on the flow field structures, pressure coefficients and aerodynamic characteristics of airfoil at relative small defect lengths. For example, the lift coefficients decrease and drag coefficients increase sharply after the appearance of leading edge defect. However, the aerodynamic characteristics could reach a constant value when the defect length is large enough. The flow field, pressure coefficient distribution and aerodynamic coefficients do not change a lot when the defect lengths reach to 0.5%c,1%c, 2%c and 3%c with defect thicknesses of 6%tc, 12%tc,18%tc and 25%tc, respectively. In addition, the results also show that the critical defect length/thickness ratio is 0.5, beyond which the aerodynamic characteristics nearly remain unchanged. In

  4. Effects of Leading Edge Defect on the Aerodynamic and Flow Characteristics of an S809 Airfoil.

    Directory of Open Access Journals (Sweden)

    Yan Wang

    Full Text Available Unexpected performance degradation occurs in wind turbine blades due to leading edge defect when suffering from continuous impacts with rain drops, hails, insects, or solid particles during its operation life. To assess this issue, this paper numerically investigates the steady and dynamic stall characteristics of an S809 airfoil with various leading edge defects. More leading edge defect sizes and much closer to practical parameters are investigated in the paper.Numerical computation is conducted using the SST k-ω turbulence model, and the method has been validated by comparison with existed published data. In order to ensure the calculation convergence, the residuals for the continuity equation are set to be less than 10-7 and 10-6 in steady state and dynamic stall cases. The simulations are conducted with the software ANSYS Fluent 13.0.It is found that the characteristics of aerodynamic coefficients and flow fields are sensitive to leading edge defect both in steady and dynamic conditions. For airfoils with the defect thickness of 6%tc, leading edge defect has a relative small influence on the aerodynamics of S809 airfoil. For other investigated defect thicknesses, leading edge defect has much greater influence on the flow field structures, pressure coefficients and aerodynamic characteristics of airfoil at relative small defect lengths. For example, the lift coefficients decrease and drag coefficients increase sharply after the appearance of leading edge defect. However, the aerodynamic characteristics could reach a constant value when the defect length is large enough. The flow field, pressure coefficient distribution and aerodynamic coefficients do not change a lot when the defect lengths reach to 0.5%c,1%c, 2%c and 3%c with defect thicknesses of 6%tc, 12%tc,18%tc and 25%tc, respectively. In addition, the results also show that the critical defect length/thickness ratio is 0.5, beyond which the aerodynamic characteristics nearly remain

  5. Separately contacted edge states: A new spectroscopic tool for the investigation of the quantum Hall effect

    OpenAIRE

    Wuertz, A.; Wildfeuer, R.; Lorke, A.; Deviatov, E. V.; Dolgopolov, V. T.

    2001-01-01

    Using an innovative combination of a quasi-Corbino sample geometry and the cross-gate technique, we have developed a method that enables us to separately contact single edge channels in the quantum Hall regime and investigate equilibration among them. Performing 4-point resistance measurements, we directly obtain information on the energetic and geometric structure of the edge region and the equilibration-length for current transport across the Landau- as well as the spin-gap. Based on an alm...

  6. Edge Matters

    DEFF Research Database (Denmark)

    Earon, Ofri

    2013-01-01

    of this container is to separate inside from outside and to protect and provide privacy, psychological as well as physical (Venturi, 1966). But, if dwelling phenomenon takes place both inside and outside the private house – why is the urban house an enclosed box? What is the differentiation between inside...... and outside the contemporary urban house? And what is the interplay between them? The research argues for re-thinking the edge zone between inside and outside the urban house. Therefore, although, residential buildings in the city are the objects of study, the focal point here is the edge zone along...... the building. The research explores and develops the architectural characteristics of correlations between the resident, the singular unit, the building and the given location at the edge zone. It approaches the edge zone of the urban house as a platform for dynamic interactions between these behaviours...

  7. Effect of Wavy Trailing Edge on 100meter Flatback Wind Turbine Blade

    International Nuclear Information System (INIS)

    Yang, SJ; Baeder, J D

    2016-01-01

    The flatback trailing edge design for modern 100meter wind turbine blade has been developed and proposed to make wind turbine blade to be slender and lighter. On the other hand, it will increase aerodynamic drag; consequently the increased drag diminishes turbine power generation. Thus, an aerodynamic drag reducing technique should be accompanied with the flatback trailing edge in order to prevent loss of turbine power generation. In this work, a drag mitigation design, span-wise wavy trailing edge blade, has been applied to a modern 100meter blade. The span-wise trailing edge acts as a vortex generator, and breaks up the strong span-wise coherent trailing edge vortex structure at the flatback airfoil trailing edge which is a major source of large drag. Three-dimensional unsteady Computational Fluid Dynamics (CFD) simulations have been performed for real scale wind turbine blade geometries. Delayed Detached Eddy Simulation (DDES) with the modified laminar-turbulent transition model has been applied to obtain accurate flow field predictions. Graphical Processor Unit (GPU)-accelerated computation has been conducted to reduce computational costs of the real scale wind turbine blade simulations. To verify the structural reliability of the wavy modification of the blade a simple Eigen buckling analysis has been performed in the current study. (paper)

  8. Harvest-related edge effects on prey availability and foraging of hooded warblers in a bottomland hardwood forest

    Science.gov (United States)

    John C. Kilgo

    2005-01-01

    The effects of harvest-created canopy gaps in bottomland hardwood forests on arthropod abundance and, hence, the foraging ecology of birds are poorly understood. I predicted that arthropod abundance would be high near edges of group-selection harvest gaps and lower in the surrounding forest, and that male Hooded Warblers (Wilsonia citrina) foraging...

  9. Investigation of CeO2 Buffer Layer Effects on the Voltage Response of YBCO Transition-Edge Bolometers

    DEFF Research Database (Denmark)

    Mohajeri, Roya; Nazifi, Rana; Wulff, Anders Christian

    2016-01-01

    The effect on the thermal parameters of superconducting transition-edge bolometers produced on a single crystalline SrTiO3 (STO) substrate with and without a CeO2 buffer layer was investigated. Metal-organic deposition was used to deposit the 20-nm CeO2 buffer layer, whereas RF magnetron sputtering...

  10. Edge effect of low-traffic forest roads on bird communities in secondary production forests in central Europe

    Czech Academy of Sciences Publication Activity Database

    Šálek, M.; Svobodová, Jana; Zasadil, P.

    2010-01-01

    Roč. 25, č. 7 (2010), s. 1113-1124 ISSN 0921-2973 Institutional research plan: CEZ:AV0Z60930519 Keywords : Biodiversity * Bird assemblages * Czech Republic * Edge effect * Habitat fragmentation * Landscape structure * Point count method Subject RIV: EH - Ecology, Behaviour Impact factor: 3.200, year: 2010

  11. On the Cutting Edge Professional Development Program - An effective model built from years of experience

    Science.gov (United States)

    Bruckner, M. Z.; Macdonald, H.; Beane, R. J.; Manduca, C. A.; Mcconnell, D. A.; Mogk, D. W.; Tewksbury, B. J.; Wiese, K.; Wysession, M. E.; Iverson, E. A. R.; Fox, S.

    2015-12-01

    The On the Cutting Edge (CE) program offers a successful model for designing and convening professional development events. Information about the model is now available on the CE website. The program model has evolved from more than 12 years of experience, building with input from strong leaders and participants. CE offers face-to-face, virtual, and hybrid events, and features a rich website that supports these professional development events as well as a growing community with a shared interest in effective geoscience teaching. Data from national surveys, participant feedback, and self-report data indicate the program's success in improving undergraduate geoscience education. Successes are also demonstrated in classroom observations using RTOP, indicating a significant difference in teaching style among participants and non-participants. A suite of web pages, with a planning timeline, provides guidance to those interested in designing and convening face-to-face or virtual events based on the CE model. The pages suggest ways to develop robust event goals and evaluation tools, how to choose strong leaders and recruit diverse participants, advice for designing effective event programs that utilize participant expertise, websites, and web tools, and suggestions for effectively disseminating event results and producing useful products. The CE model has been successfully transferred to projects that vary in scale and discipline. Best practices from the CE model include (1) thinking of the workshop as shared enterprise among conveners and participants; (2) incorporating conveners and participants who bring diverse viewpoints and approaches; (3) promoting structured discussions that utilize participants' expertise; (4) emphasizing practical strategies to effect change; and (5) using the website as a platform to prepare for the workshop, share ideas, and problem-solve challenges. Learn more about how to utilize this model for your project at:serc.carleton.edu/NAGTWorkshops/workshops/convene

  12. An investigation of unsteady 3-D effects on trailing edge flaps

    Directory of Open Access Journals (Sweden)

    E. Jost

    2017-05-01

    Full Text Available The present study investigates the impact of unsteady 3-D aerodynamic effects on a wind turbine blade with trailing edge flap by means of computational fluid dynamics (CFD. Harmonic oscillations are simulated on the DTU 10 MW rotor with a morphing flap of 10 % chord extent ranging from 70 to 80 % blade radius. The deflection frequency is varied in the range between 1 and 6 p. To quantify 3-D effects, rotor simulations are compared to 2-D airfoil computations and the 2-D theory by Theodorsen. It was found that the deflection of the flap on the 3-D rotor causes a complex wake development and induction which influences the loads over large parts of the blade. In particular, the rotor near wake with its trailing and shed vortex structures revealed a great impact. Trailing vorticity, a 3-D phenomenon, is caused by the gradient of bound circulation along the blade span. Shed vorticity originates from the temporal bound circulation gradient and is thus also apparent in 2-D. Both lead to an amplitude reduction and shed vorticity additionally to a hysteresis of the lift response with regard to the deflection signal in the flap section. A greater amplitude reduction and a less pronounced hysteresis is observed on the 3-D rotor compared to the 2-D airfoil case. Blade sections neighboring the flap experience, however, an opposing impact and hence partly compensate for the negative effect of trailing vortices in the flap section with respect to integral loads. Comparisons to steady flap deflections at the 3-D rotor revealed the high influence of dynamic inflow effects.

  13. Defining the effect of sweep tillage tool cutting edge geometry on tillage forces using 3D discrete element modelling

    Directory of Open Access Journals (Sweden)

    Mustafa Ucgul

    2015-09-01

    Full Text Available The energy required for tillage processes accounts for a significant proportion of total energy used in crop production. In many tillage processes decreasing the draft and upward vertical forces is often desired for reduced fuel use and improved penetration, respectively. Recent studies have proved that the discrete element modelling (DEM can effectively be used to model the soil–tool interaction. In his study, Fielke (1994 [1] examined the effect of the various tool cutting edge geometries, namely; cutting edge height, length of underside rub, angle of underside clearance, on draft and vertical forces. In this paper the experimental parameters of Fielke (1994 [1] were simulated using 3D discrete element modelling techniques. In the simulations a hysteretic spring contact model integrated with a linear cohesion model that considers the plastic deformation behaviour of the soil hence provides better vertical force prediction was employed. DEM parameters were determined by comparing the experimental and simulation results of angle of repose and penetration tests. The results of the study showed that the simulation results of the soil-various tool cutting edge geometries agreed well with the experimental results of Fielke (1994 [1]. The modelling was then used to simulate a further range of cutting edge geometries to better define the effect of sweep tool cutting edge geometry parameters on tillage forces. The extra simulations were able to show that by using a sharper cutting edge with zero vertical cutting edge height the draft and upward vertical force were further reduced indicating there is benefit from having a really sharp cutting edge. The extra simulations also confirmed that the interpolated trends for angle of underside clearance as suggested by Fielke (1994 [1] where correct with a linear reduction in draft and upward vertical force for angle of underside clearance between the ranges of −25 and −5°, and between −5 and 0°. The

  14. Prediction of Film Cooling Effectiveness on a Gas Turbine Blade Leading Edge Using ANN and CFD

    Science.gov (United States)

    Dávalos, J. O.; García, J. C.; Urquiza, G.; Huicochea, A.; De Santiago, O.

    2018-05-01

    In this work, the area-averaged film cooling effectiveness (AAFCE) on a gas turbine blade leading edge was predicted by employing an artificial neural network (ANN) using as input variables: hole diameter, injection angle, blowing ratio, hole and columns pitch. The database used to train the network was built using computational fluid dynamics (CFD) based on a two level full factorial design of experiments. The CFD numerical model was validated with an experimental rig, where a first stage blade of a gas turbine was represented by a cylindrical specimen. The ANN architecture was composed of three layers with four neurons in hidden layer and Levenberg-Marquardt was selected as ANN optimization algorithm. The AAFCE was successfully predicted by the ANN with a regression coefficient R2<0.99 and a root mean square error RMSE=0.0038. The ANN weight coefficients were used to estimate the relative importance of the input parameters. Blowing ratio was the most influential parameter with relative importance of 40.36 % followed by hole diameter. Additionally, by using the ANN model, the relationship between input parameters was analyzed.

  15. Effects of Roof-Edge Roughness on Air Temperature and Pollutant Concentration in Urban Canyons

    Science.gov (United States)

    Aliabadi, Amir A.; Krayenhoff, E. Scott; Nazarian, Negin; Chew, Lup Wai; Armstrong, Peter R.; Afshari, Afshin; Norford, Leslie K.

    2017-08-01

    The influence of roof-edge roughness elements on airflow, heat transfer, and street-level pollutant transport inside and above a two-dimensional urban canyon is analyzed using an urban energy balance model coupled to a large-eddy simulation model. Simulations are performed for cold (early morning) and hot (mid afternoon) periods during the hottest month of the year (August) for the climate of Abu Dhabi, United Arab Emirates. The analysis suggests that early in the morning, and when the tallest roughness elements are implemented, the temperature above the street level increases on average by 0.5 K, while the pollutant concentration decreases by 2% of the street-level concentration. For the same conditions in mid afternoon, the temperature decreases conservatively by 1 K, while the pollutant concentration increases by 7% of the street-level concentration. As a passive or active architectural solution, the roof roughness element shows promise for improving thermal comfort and air quality in the canyon for specific times, but this should be further verified experimentally. The results also warrant a closer look at the effects of mid-range roughness elements in the urban morphology on atmospheric dynamics so as to improve parametrizations in mesoscale modelling.

  16. Effect of static charge fluctuations on the conduction along the edge of two-dimensional topological insulator

    Science.gov (United States)

    Vayrynen, Jukka; Goldstein, Moshe; Glazman, Leonid

    2013-03-01

    Static charge disorder may create electron puddles in the bulk of a material which nominally is in the insulating state. A single puddle - quantum dot - coupled to the helical edge of a two-dimensional topological insulator enhances the electron backscattering within the edge. The backscattering rate increases with the electron dwelling time in the dot. While remaining inelastic, the backscattering off a dot may be far more effective than the proposed earlier inelastic processes involving a local scatterer with no internal structure. We find the temperature dependence of the dot-induced correction to the universal conductance of the edge. In addition to the single-dot effect, we calculate the classical temperature-independent conductance correction caused by a weakly conducting bulk. We use our theory to assess the effect of static charge fluctuations in a heterostructure on the edge electron transport in a two-dimensional topological insulator. The work at Yale University is supported by NSF DMR Grant No. 1206612 and the Simons Foundation.

  17. Adjustment of Sentinel-2 Multi-Spectral Instrument (MSI Red-Edge Band Reflectance to Nadir BRDF Adjusted Reflectance (NBAR and Quantification of Red-Edge Band BRDF Effects

    Directory of Open Access Journals (Sweden)

    David P. Roy

    2017-12-01

    Full Text Available Optical wavelength satellite data have directional reflectance effects over non-Lambertian surfaces, described by the bidirectional reflectance distribution function (BRDF. The Sentinel-2 multi-spectral instrument (MSI acquires data over a 20.6° field of view that have been shown to have non-negligible BRDF effects in the visible, near-infrared, and short wave infrared bands. MSI red-edge BRDF effects have not been investigated. In this study, they are quantified by an examination of 6.6 million (January 2016 and 10.7 million (April 2016 pairs of forward and back scatter reflectance observations extracted over approximately 20° × 10° of southern Africa. Non-negligible MSI red-edge BRDF effects up to 0.08 (reflectance units across the 290 km wide MSI swath are documented. A recently published MODIS BRDF parameter c-factor approach to adjust MSI visible, near-infrared, and short wave infrared reflectance to nadir BRDF-adjusted reflectance (NBAR is adapted for application to the MSI red-edge bands. The red-edge band BRDF parameters needed to implement the algorithm are provided. The parameters are derived by a linear wavelength interpolation of fixed global MODIS red and NIR BRDF model parameters. The efficacy of the interpolation is investigated using POLDER red, red-edge, and NIR BRDF model parameters, and is shown to be appropriate for the c-factor NBAR generation approach. After adjustment to NBAR, red-edge MSI BRDF effects were reduced for the January data (acquired close to the solar principal where BRDF effects are maximal and the April data (acquired close to the orthogonal plane for all the MSI red-edge bands.

  18. Influence of the voltage polarity on the properties of a nanosecond surface barrier discharge in atmospheric-pressure air

    International Nuclear Information System (INIS)

    Nudnova, M. M.; Aleksandrov, N. L.; Starikovskii, A. Yu.

    2010-01-01

    The properties of a surface barrier discharge in atmospheric-pressure air at different polarities of applied voltage were studied experimentally. The influence of the voltage polarity on the spatial structure of the discharge and the electric field in the discharge plasma was determined by means of spectroscopic measurements. It is found that the energy deposited in the discharge does not depend on the voltage polarity and that discharges of positive polarity are more homogenous and the electric fields in them are higher.

  19. Measuring variation of indoor radon concentration using bare nuclear tracks detectors, scintillation counters and surface barrier detectors

    International Nuclear Information System (INIS)

    Ishak, I.; Mahat, R.H.; Amin, Y.M.

    1996-01-01

    Bare LRI 15 nuclear track detectors , scintillators counter and surface barrier detectors were used to measured the indoor radon concentration in various location within two rooms. Spatial variation of the radon concentration is caused by positioning of the door, windows, furniture, cracks in the building and also distances from floor, wall and ceiling. It is found that the change in temperature are causing radon concentration to increase at certain time of the day

  20. Design and construction of a system for determination of Radon-222 by a surface-barrier detector

    International Nuclear Information System (INIS)

    Bonifacio M, J.; Iturbe, J.L.

    1993-01-01

    In the present work the design and construction of a system for the determination of 222 Rn is described, which utilizes silicon surface-barrier detectors. The 222 Rn gas was obtained a source of 226 Ra electrodeposited on stainless-steel discs. The well separated energies with this system makes possible the measurement and identification of alpha particles of 222 Rn, and its daughters 210 Po, 218 Po and 214 Po. (Author) 3 figs, 19 refs

  1. Effects of free-stream turbulence intensity and blowing ratio on film cooling of turbine blade leading edge

    International Nuclear Information System (INIS)

    Kim, S. M.; Kim, Youn J.; Cho, H. H.

    2001-01-01

    We used a cylindrical model which simulates turbine blade leading edge to investigate the effects of free-stream turbulence intensity and blowing ratio on film cooling of turbine blade leading edge. Tests are carried out in a low-speed wind tunnel on a cylindrical model with three rows of injection holes. Mainstream Reynolds number based on the cylinder diameter was 7.1x10 4 . Two types of turbulence grid are used to increase a free-stream turbulence intensity. The effect of coolant blowing ratio was studied for various blowing ratios. For each blowing ratios, wall temperatures around the surface of the test model are measured by thermocouples installed inside the model. Results show that blowing ratios have small effect on spanwise-averaged film effectiveness at high free-stream turbulence intensity. However, an increase in free-stream turbulence intensity enhances significantly spanwise-averaged film effectiveness at low blowing ratio

  2. Modeling and Simulation of Long-Term Performance of Near-Surface Barriers

    International Nuclear Information System (INIS)

    Piet, S. J.; Jacobson, J. J.; Martian, P.; Martineau, R.; Soto, R.

    2003-01-01

    Society has and will continue to generate hazardous wastes whose risks must be managed. For exceptionally toxic, long-lived, and feared waste, the solution is deep burial, e.g., deep geological disposal at Yucca Mtn. For some waste, recycle or destruction/treatment is possible. The alternative for other wastes is storage at or near the ground level (in someone's back yard); most of these storage sites include a surface barrier (cap) to prevent migration of the waste due to infiltration of surface water. The design lifespan for such barriers ranges from 30 to 1000 years, depending on hazard and regulations. In light of historical performance, society needs a better basis for predicting barrier performance over long time periods and tools for optimizing maintenance of barriers while in service. We believe that, as in other industries, better understanding of the dynamics of barrier system degradation will enable improved barriers (cheaper, longer-lived, simpler, easier to maintain) and improved maintenance. We are focusing our research on earthen caps, especially those with evapo-transpiration and capillary breaks. Typical cap assessments treat the barrier's structure as static prior to some defined lifetime. Environmental boundary conditions such as precipitation and temperature are treated as time dependent. However, other key elements of the barrier system are regarded as constant, including engineered inputs (e.g., fire management strategy, irrigation, vegetation control), surface ecology (critical to assessment of plant transpiration), capillary break interface, material properties, surface erosion rate, etc. Further, to be conservative, only harmful processes are typically considered. A more holistic examination of both harmful and beneficial processes will provide more realistic pre-service prediction and in-service assessment of performance as well as provide designers a tool to encourage beneficial processes while discouraging harmful processes. Thus, the

  3. Development of a alpha spectrometer system with the surface barrier detector

    International Nuclear Information System (INIS)

    Alencar, Marcus Alexandre Vallini de

    1994-04-01

    The aim of this work is the development of an α spectrometer of low cost and home made technology. The spectrometer is mounted in a double NIM module and includes a surface barrier detector and dedicate electronic system. Six barrier surface detectors were made, three of which with η type silicon wafer 3350 Ω.cm, 270mm 2 and three other with ρ type silicon wafer 5850 Ω.cm and 220mm 2 . The rectifier and the ohmic contacts were prepared at high vacuum (10 -2 to 10 -3 Pa) evaporation with 40μg/cm 2 of Au and Al respectively for the η type detectors, and with Al and Au respectively for the ρ type detectors. The electronic system is composed by a low noise charge sensitive preamplifier with the operational amplifier LF-356 mounted with 1OOMΩ feedback resistor and a 0.5 pF capacitor. The linear amplifier is also based in the LF-356 and the LM-310 operational amplifier. The bipolar output is formatted through a (CR) 2- (RC) 4 shaping network and the unipolar output is obtained through a CR-(RC) 4 shaping system which is sufficient to realize a almost true Gaussian shaping pulse with a time constant of 3.0μs. This format was chosen because we can expect a low counting rate and the gaussian pulse can improve the signal/noise ratio. The first CR differentiation has also a active pole-zero cancellation network.The resolution of detectors for 241 Am α particles at room temperature (24 degree) vary 21 to 44 keV FWHM. The electronic noise of the noise of the system is 7.5 keV FWHM at OpF input capacitance. The overall resolution of the spectrometer was found to be 62 keV FWHM at room temperature. The simplicity of the electronic system, the low cost of the construction and the overall resolution show that this alpha spectrometer can be readily used in measurements where high resolution is not a premium. (author)

  4. Elevated Levels of Herbivory in Urban Landscapes: Are Declines in Tree Health More Than an Edge Effect?

    Directory of Open Access Journals (Sweden)

    Fiona J. Christie

    2005-06-01

    Full Text Available Urbanization is one of the most extreme and rapidly growing anthropogenic pressures on the natural world. Urban development has led to substantial fragmentation of areas of natural habitat, resulting in significant impacts on biodiversity and disruptions to ecological processes. We investigated the levels of leaf damage caused by invertebrates in a dominant canopy species in urban remnants in a highly fragmented urban landscape in Sydney, Australia, by assessing the frequency and extent of chewing and surface damage of leaves in urban remnants compared to the edges and interiors of continuous areas of vegetation. Although no difference was detected in the frequency of leaves showing signs of damage at small, edge, and interior sites, small sites suffered significantly greater levels of leaf damage than did interior sites. Trees at edge sites showed intermediate levels of damage, suggesting that edge effects alone are not the cause of higher levels of herbivory. These findings are the first to demonstrate the effects of urbanization on invertebrate damage in dominant trees at coarse scales. This is consistent with hypotheses predicting that changes in species composition through urban fragmentation affect ecological interactions.

  5. Plasma-surface interaction at sharp edges and corners during ion-assisted physical vapor deposition. Part I: Edge-related effects and their influence on coating morphology and composition

    International Nuclear Information System (INIS)

    Macak, E.B.; Muenz, W.-D.; Rodenburg, J.M.

    2003-01-01

    Ion-assisted physical vapor deposition (PVD) is a common industrial method for growing thin coatings of various interstitial nitride alloys. The interaction between the ions and three-dimensional nonflat samples during the deposition can, however, lead to unwanted local changes in the properties of the coating and thus its performance. We analyze the characteristics of the ion bombardment during ion-assisted PVD on sharp convex substrates and their effect on the growing coating. We show that the magnitude and the spatial extent of the edge-related changes are directly related to the characteristics of the plasma sheath around the biased edges. We examine the influence of the edge geometry and the deposition conditions. The edge-related effects are studied on the example of wedge-shaped samples coated with TiAlN/VN by closed-field unbalanced magnetron deposition process using high-flux low-energy Ar + -ion irradiation (J i /J me ∼4, E i =75-150 eV). The samples are analyzed by scanning electron microscopy and energy-dispersive x-ray spectroscopy. Significant changes in the morphology, thickness, and composition of the coatings are found in the edge region. In order to account for the changes, we apply a self-consistent model of the plasma sheath around wedge-shaped samples proposed by Watterson [J. Phys. D 22, 1300 (1989)], to our conditions. For a 30 deg. wedge coated at -150 V, the resputtering rate in the edge region is found to be increased by up to ten times as compared to flat substrate areas. The effect is due to the combined action of an increased ion flux and increased sputtering yield as a result of the nonperpendicular angle of incidence of ions in the edge region. The situation at sharp corners, where even more severe effects are observed, is analyzed and modeled in the companion article E. B. Macak et al., J. Appl. Phys. (2003) (Part II)

  6. Enhancement of broadband optical absorption in photovoltaic devices by band-edge effect of photonic crystals.

    Science.gov (United States)

    Tanaka, Yoshinori; Kawamoto, Yosuke; Fujita, Masayuki; Noda, Susumu

    2013-08-26

    We numerically investigate broadband optical absorption enhancement in thin, 400-nm thick microcrystalline silicon (µc-Si) photovoltaic devices by photonic crystals (PCs). We realize absorption enhancement by coupling the light from the free space to the large area resonant modes at the photonic band-edge induced by the photonic crystals. We show that multiple photonic band-edge modes can be produced by higher order modes in the vertical direction of the Si photovoltaic layer, which can enhance the absorption on multiple wavelengths. Moreover, we reveal that the photonic superlattice structure can produce more photonic band-edge modes that lead to further optical absorption. The absorption average in wavelengths of 500-1000 nm weighted to the solar spectrum (AM 1.5) increases almost twice: from 33% without photonic crystal to 58% with a 4 × 4 period superlattice photonic crystal; our result outperforms the Lambertian textured structure.

  7. The effect of spin-orbit coupling in band structure and edge states of bilayer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Sahdan, Muhammad Fauzi; Darma, Yudi, E-mail: yudi@fi.itb.ac.id [Department of Physics, InstitutTeknologi Bandung, Jalan Ganesa 10, Bandung 40132 (Indonesia)

    2015-04-16

    Topological insulators are predicted to be useful ranging from spintronics to quantum computation. Graphene was first predicted to be the precursor of topological insulator by Kane-Mele. They developed a Hamiltonian model to describe the gap opening in graphene. In this work, we investigate the band structure of bilayer grapheme and also its edge states by using this model with analytical approach. The results of our calculation show that the gap opening occurs at K and K’ point in bilayer graphene.In addition, a pair of gapless edge modes occurs both in the zigzag and arm-chair configurations are no longer exist. There are gap created at the edge even though thery are very small.

  8. The effect of motion patterns on edge-loading of metal-on-metal hip resurfacing.

    Science.gov (United States)

    Mellon, S J; Kwon, Y-M; Glyn-Jones, S; Murray, D W; Gill, H S

    2011-12-01

    The occurrence of pseudotumours (soft tissue masses relating to the hip joint) following metal-on-metal hip resurfacing arthroplasty (MoMHRA) has been associated with high serum metal ion levels and consequently higher than normal bearing wear. We investigated the relationship between serum metal ion levels and contact stress on the acetabular component of MoMHRA patients for two functional activities; gait and stair descent. Four subjects with MoMHRA, who had their serum metal ion levels measured, underwent motion analysis followed by CT scanning. Their motion capture data was combined with published hip contact forces and finite element models representing 14% (peak force) and 60% (end of stance) of the gait cycle and 52% (peak force) of stair descent activity were created. The inclination angle of the acetabular component was increased by 10° in 1° intervals and the contact stresses were determined at each interval for each subject. When the inclination angle was altered in such a way as to cause the hip contact force to pass through the edge of the acetabular component edge-loading occurred. Edge-loading increased the contact stress by at least 50%; the maximum increase was 108%. Patients with low serum metal ion levels showed no increase in contact stress at peak force during gait or stair descent. Patients with high serum metal ion levels exhibited edge-loading with an increase to the inclination angle of their acetabular components. The increase in inclination angle that induced edge-loading for these subjects was less than the inter-subject variability in the angle of published hip contact forces. The results of this study suggest that high serum metal ion levels are the result of inclination angle influenced edge-loading but that edge-loading cannot be attributed to inclination angle alone and that an individual's activity patterns can reduce or even override the influence of a steep acetabular component and prevent edge-loading. Copyright © 2011 IPEM

  9. Effect of smile index and incisal edge position on perception of attractiveness in different age groups.

    Science.gov (United States)

    Chou, J-C; Nelson, A; Katwal, D; Elathamna, E N; Durski, M T

    2016-11-01

    Changes in occlusal vertical dimension (OVD) and age have been found to affect Smile Index (SI, width/height of smile). Limited information is available regarding the aesthetic effects of these changes. The objective of this study was to evaluate the attractiveness of digitally manipulated smile images with differences in SI and incisal edge position (IEP) judged by respondents in different age groups. A total of 12 smile images were generated with varying SI (3·5, 5·3, 7·2, 9·0) and IEP (High, Medium, Low). Fifty respondents each in four age groups (15-24, 25-39, 40-54, 55+) evaluated the attractiveness of the 12 images using a 0-10 visual analog scale (VAS, 10 being most attractive). A repeated-measures three-factorial mixed model assessed differences. SI, IEP and age of respondents were found to significantly influence attractiveness score (P age groups combined, SI = 7·2/IEP = Medium was most attractive (VAS = 7·22), followed by SI = 9·0/IEP = Medium, and SI = 5·3/IEP = Medium (VAS = 6·53 and 6·48, respectively). SI = 3·5/IEP = High and SI = 3·5/IEP = Low were least attractive (VAS = 1·99 and VAS = 2·58, respectively). Age group significantly influenced aesthetic perception, with younger respondents more critical in differences in SI and IEP. SI and IEP significantly influenced attractiveness of the smile in all respondent age groups. Low SI (i.e. 3·5) combined with high or low IEP was unattractive. Medium SI to high SI (i.e. 5·3-9·0) combined with medium IEP were considered attractive. © 2016 John Wiley & Sons Ltd.

  10. The effect of butterfly-scale inspired patterning on leading-edge vortex growth

    Science.gov (United States)

    Wilroy, Jacob Aaron

    Leading edge vortices (LEVs) are important for generating thrust and lift in flapping flight, and the surface patterning (scales) on butterfly wings is hypothesized to play a role in the vortex formation of the LEV. To simplify this complex flow problem, an experiment was designed to focus on the alteration of 2-D vortex development with a variation in surface patterning. Specifically, the secondary vorticity generated by the LEV interacting at the patterned surface was studied, as well as the subsequent effect on the LEV's growth rate and peak circulation. For this experiment, rapid-prototyped grooves based on the scale geometry of the Monarch butterfly (Danaus plexippus) were created using additive manufacturing and were attached to a flat plate with a chordwise orientation, thus increasing plate surface area. The vortex generated by the grooved plate was then compared to a smooth plate case in an experiment where the plate translated vertically through a 2 x 3 x 5 cubic foot tow tank. The plate was impulsively started in quiescent water and flow fields at Rec = 1416, 2833, and 5667 are examined using Digital Particle Image Velocimetry (DPIV). The maximum vortex formation number is 2.8 and is based on the flat plate travel length and chord length. Flow fields from each case show the generation of a secondary vortex whose interaction with the shear layer and LEV caused different behaviors depending upon the surface type. The vortex development process varied for each Reynolds number and it was found that for the lowest Reynolds number case a significant difference does not exist between surface types, however, for the other two cases the grooves affected the secondary vortex's behavior and the LEV's ability to grow at a rate similar to the smooth plate case.

  11. The effect of microstructure on the sheared edge quality and hole expansion ratio of hot-rolled 700 MPa steel

    Science.gov (United States)

    Kaijalainen, A.; Kesti, V.; Vierelä, R.; Ylitolva, M.; Porter, D.; Kömi, J.

    2017-09-01

    The effects of microstructure on the cutting and hole expansion properties of three thermomechanically rolled steels have been investigated. The yield strength of the studied 3 mm thick strip steels was approximately 700 MPa. Detailed microstructural studies using laser scanning confocal microscopy (LCSM), FESEM and FESEM-EBSD revealed that the three investigated materials consist of 1) single-phase polygonal ferrite, 2) polygonal ferrite with precipitates and 3) granular bainite. The quality of mechanically sheared edges were evaluated using visual inspection and LSCM, while hole expansion properties were characterised according to the methods described in ISO 16630. Roughness values (Ra and Rz) of the sheet edge with different cutting clearances varied between 12 µm to 21 µm and 133 µm to 225 µm, respectively. Mean hole expansion ratios varied from 28.4% to 40.5%. It was shown that granular bainite produced the finest cutting edge, but the hole expansion ratio remained at the same level as in the steel comprising single-phase ferrite. This indicates that a single-phase ferritic matrix enhances hole expansion properties even with low quality edges. A brief discussion of the microstructural features controlling the cutting quality and hole expansion properties is given.

  12. Computational nanometrology of line-edge roughness: noise effects, cross-line correlations and the role of etch transfer

    Science.gov (United States)

    Constantoudis, Vassilios; Papavieros, George; Lorusso, Gian; Rutigliani, Vito; Van Roey, Frieda; Gogolides, Evangelos

    2018-03-01

    The aim of this paper is to investigate the role of etch transfer in two challenges of LER metrology raised by recent evolutions in lithography: the effects of SEM noise and the cross-line and edge correlations. The first comes from the ongoing scaling down of linewidths, which dictates SEM imaging with less scanning frames to reduce specimen damage and hence with more noise. During the last decade, it has been shown that image noise can be an important budget of the measured LER while systematically affects and alter the PSD curve of LER at high frequencies. A recent method for unbiased LER measurement is based on the systematic Fourier or correlation analysis to decompose the effects of noise from true LER (Fourier-Correlation filtering method). The success of the method depends on the PSD and HHCF curve. Previous experimental and model works have revealed that etch transfer affects the PSD of LER reducing its high frequency values. In this work, we estimate the noise contribution to the biased LER through PSD flat floor at high frequencies and relate it with the differences between the PSDs of lithography and etched LER. Based on this comparison, we propose an improvement of the PSD/HHCF-based method for noise-free LER measurement to include the missed high frequency real LER. The second issue is related with the increased density of lithographic patterns and the special characteristics of DSA and MP lithography patterns exhibits. In a previous work, we presented an enlarged LER characterization methodology for such patterns, which includes updated versions of the old metrics along with new metrics defined and developed to capture cross-edge and cross-line correlations. The fundamental concept has been the Line Center Roughness (LCR), the edge c-factor and the line c-factor correlation function and length quantifying the line fluctuations and the extent of cross-edge and cross-line correlations. In this work, we focus on the role of etch steps on cross-edge and

  13. Effect of guide wall on jet impingement cooling in blade leading edge channel

    International Nuclear Information System (INIS)

    Zhao, Qing-Yang; Chung, Heeyoon; Choi, Seok Min; Cho, Hyung Hee

    2016-01-01

    The characteristics of fluid flow and heat transfer, which are affected by the guide wall in a jet impinged leading edge channel, have been investigated numerically using three-dimensional Reynolds-averaged Navier-Stokes analysis via the shear stress transport turbulence model and gamma theta transitional turbulence model. A constant wall heat flux condition has been applied to the leading edge surface. The jet-to-surface distance is constant, which is three times that of the jet diameter. The arrangement of the guide wall near the jet hole is set as a variable. Results presented in this study include the Nusselt number contour, velocity vector, streamline with velocity, and local Nusselt number distribution along the central line on the leading edge surface. The average Nusselt number and average pressure loss between jet nozzle and channel exit are calculated to assess the thermal performance. The application of the guide wall is aimed at improving heat transfer uniformity on the leading edge surface. Results indicated that the streamwise guide wall ensures the vertical jet impingement flow intensity and prevents the flow after impingement to reflux into jet flow. Thus, a combined rectangular guide wall benefits the average heat transfer, thermal performance and heat transfer distribution uniformity

  14. Thermal Edge-Effects Model for Automated Tape Placement of Thermoplastic Composites

    Science.gov (United States)

    Costen, Robert C.

    2000-01-01

    Two-dimensional thermal models for automated tape placement (ATP) of thermoplastic composites neglect the diffusive heat transport that occurs between the newly placed tape and the cool substrate beside it. Such lateral transport can cool the tape edges prematurely and weaken the bond. The three-dimensional, steady state, thermal transport equation is solved by the Green's function method for a tape of finite width being placed on an infinitely wide substrate. The isotherm for the glass transition temperature on the weld interface is used to determine the distance inward from the tape edge that is prematurely cooled, called the cooling incursion Delta a. For the Langley ATP robot, Delta a = 0.4 mm for a unidirectional lay-up of PEEK/carbon fiber composite, and Delta a = 1.2 mm for an isotropic lay-up. A formula for Delta a is developed and applied to a wide range of operating conditions. A surprise finding is that Delta a need not decrease as the Peclet number Pe becomes very large, where Pe is the dimensionless ratio of inertial to diffusive heat transport. Conformable rollers that increase the consolidation length would also increase Delta a, unless other changes are made, such as proportionally increasing the material speed. To compensate for premature edge cooling, the thermal input could be extended past the tape edges by the amount Delta a. This method should help achieve uniform weld strength and crystallinity across the width of the tape.

  15. Nickel doping effect on resistance to movement of edge dislocations in α-Fe

    International Nuclear Information System (INIS)

    Brovkov, V.A.; Dudarev, E.F.

    1984-01-01

    Microplastic deformation of α-Fe polycrystals and Fe-Ni solid solutions is studied. Data on concentration and temperature dependences of a resistance to movement of edge dislocation at the expense of elastic interaction with atoms of the doping element are obtained

  16. Edge effects on forces and magnetic fields produced by a conductor moving past a magnet

    Energy Technology Data Exchange (ETDEWEB)

    Mulcahy, T.M.; Hull, J.R.; Almer, J.D. (Argonne National Lab., IL (United States)); Rossing, T.D. (Northern Illinois Univ., De Kalb, IL (United States))

    1992-01-01

    Experiments have been performed to further understand the forces acting on magnets moving along and over the edge of a continuous conducting sheet and to produce a comprehensive data set for the validation of analysis methods. Mapping the magnetic field gives information about the eddy currents induced in the conductor, which agrees with numerical calculations.

  17. Edge effects on forces and magnetic fields produced by a conductor moving past a magnet

    Energy Technology Data Exchange (ETDEWEB)

    Mulcahy, T.M.; Hull, J.R.; Almer, J.D. [Argonne National Lab., IL (United States); Rossing, T.D. [Northern Illinois Univ., De Kalb, IL (United States)

    1992-04-01

    Experiments have been performed to further understand the forces acting on magnets moving along and over the edge of a continuous conducting sheet and to produce a comprehensive data set for the validation of analysis methods. Mapping the magnetic field gives information about the eddy currents induced in the conductor, which agrees with numerical calculations.

  18. Nickel doping effect on resistance to movement of edge dislocations in. cap alpha. -Fe

    Energy Technology Data Exchange (ETDEWEB)

    Brovkov, V.A.; Dudarev, E.F. (Tomskij Gosudarstvennyj Univ. (USSR). Sibirskij Fiziko-Tekhnicheskij Inst.)

    1984-03-01

    Microplastic deformation of ..cap alpha..-Fe polycrystals and Fe-Ni solid solutions is studied. Data on the concentration and temperature dependences of resistance to movement of edge dislocation at the expense of elastic interaction with atoms of the doping element are obtained.

  19. Helical edge states and fractional quantum Hall effect in a graphene electron-hole bilayer.

    Science.gov (United States)

    Sanchez-Yamagishi, Javier D; Luo, Jason Y; Young, Andrea F; Hunt, Benjamin M; Watanabe, Kenji; Taniguchi, Takashi; Ashoori, Raymond C; Jarillo-Herrero, Pablo

    2017-02-01

    Helical 1D electronic systems are a promising route towards realizing circuits of topological quantum states that exhibit non-Abelian statistics. Here, we demonstrate a versatile platform to realize 1D systems made by combining quantum Hall (QH) edge states of opposite chiralities in a graphene electron-hole bilayer at moderate magnetic fields. Using this approach, we engineer helical 1D edge conductors where the counterpropagating modes are localized in separate electron and hole layers by a tunable electric field. These helical conductors exhibit strong non-local transport signals and suppressed backscattering due to the opposite spin polarizations of the counterpropagating modes. Unlike other approaches used for realizing helical states, the graphene electron-hole bilayer can be used to build new 1D systems incorporating fractional edge states. Indeed, we are able to tune the bilayer devices into a regime hosting fractional and integer edge states of opposite chiralities, paving the way towards 1D helical conductors with fractional quantum statistics.

  20. Neutral particle and radiation effects on Pfirsch - Schlueter fluxes near the edge

    International Nuclear Information System (INIS)

    Catto, P.J.; Helander, P.; Connor, J.W.; Hazeltine, R.D.

    1998-01-01

    The edge plasma of a tokamak is affected by atomic physics processes and can have density and temperature variations along the magnetic field that strongly modify edge transport. A closed system of equations in the Pfirsch - Schlueter regime is presented that can be solved for the radial and poloidal variation of the plasma density, electron and ion temperatures, and the electrostatic potential in the presence of neutrals and a poloidally asymmetric energy radiation sink due to inelastic electron collisions. Neutrals have a large diffusivity so their viscosity and heat flux can become important even when their density is not high, in which case the neutral viscosity alters the electrostatic potential at the edge by introducing strong radial variation. The strong parallel gradient in the electron temperature that can arise in the presence of a localized radiation sink drives a convective flow of particles and heat across the field. This plasma transport mechanism can balance the neutral influx and is particularly strong if multifaceted asymmetric radiation from the edge (MARFE) occurs, since the electron temperature then varies substantially over the flux surface. copyright 1998 American Institute of Physics

  1. Edge placement error control and Mask3D effects in High-NA anamorphic EUV lithography

    Science.gov (United States)

    van Setten, Eelco; Bottiglieri, Gerardo; de Winter, Laurens; McNamara, John; Rusu, Paul; Lubkoll, Jan; Rispens, Gijsbert; van Schoot, Jan; Neumann, Jens Timo; Roesch, Matthias; Kneer, Bernhard

    2017-10-01

    To enable cost-effective shrink at the 3nm node and beyond, and to extend Moore's law into the next decade, ASML is developing a new high-NA EUV platform. The high-NA system is targeted to feature a numerical aperture (NA) of 0.55 to extend the single exposure resolution limit to 8nm half pitch. The system is being designed to achieve an on-product-overlay (OPO) performance well below 2nm, a high image contrast to drive down local CD errors and to obtain global CDU at sub-1nm level to be able to meet customer edge placement error (EPE) requirements for the devices of the future. EUV scanners employ reflective Bragg multi-layer mirrors in the mask and in the Projection Optics Box (POB) that is used to project the mask pattern into the photoresist on the silicon wafer. These MoSi multi-layer mirrors are tuned for maximum reflectivity, and thus productivity, at 13.5nm wavelength. The angular range of incident light for which a high reflectivity at the reticle can be obtained is limited to +/- 11o, exceeding the maximum angle occurring in current 0.33NA scanners at 4x demagnification. At 0.55NA the maximum angle at reticle level would extend up to 17o in the critical (scanning) direction and compromise the imaging performance of horizontal features severely. To circumvent this issue a novel anamorphic optics design has been introduced, which has a 4x demagnification in the X- (slit) direction and 8x demagnification in the Y- (scanning) direction as well as a central obscuration in the exit pupil. In this work we will show that the EUV high-NA anamorphic concept can successfully solve the angular reflectivity issues and provide good imaging performance in both directions. Several unique imaging challenges in comparison to the 0.33NA isomorphic baseline are being studied, such as the impact of the central obscuration in the POB and Mask-3D effects at increased NA that seem most pronounced for vertical features. These include M3D induced contrast loss and non

  2. Effect of stand edge on the natural regeneration of spruce, beech and Douglas-fir

    Directory of Open Access Journals (Sweden)

    Lumír Dobrovolný

    2012-01-01

    Full Text Available Our work aimed at studying the strategy of woody plants regeneration during the regeneration of a spruce stand with the admixture of beech and Douglas-fir by border cutting (NW-SE aspect on acidic sites of higher elevations in the Bohemian-Moravian Upland. Spruce is better adapted to bear shade than Douglas-fir. Nevertheless, in optimal light conditions up to a distance of ca. 35 m (about 16% DIFFSF from the stand edge, the Douglas-fir can put the spruce into danger as to height growth. By contrast to beech, the density of spruce is significantly higher within the distance of 45 m (about 15% DIFFSF from the stand edge but further on the situation would change to the benefit of beech. The density of Douglas-fir significantly dominates over beech within a distance of 35 m from the stand edge; from 55 m (less than 15% DIFFSF, the situation changes in favour of beech. Beech can survive in full shade deep in the stand core waiting for its opportunity to come. As compared to spruce and Douglas-fir, the height growth of beech was at all times significantly greater at a distance of 25 m from the stand edge. Converted to practical conditions, spruce and Douglas-fir with individually admixed beech seedlings showed good prosperity approximately up to a distance of one stand height from the edge. A mixture of spruce and beech did well at a greater distance but good prosperity at a distance of 2–3 stand heights was shown only by beech. Thus, border regeneration eliminates disadvantages of the climatic extremes of clear-cutting and specifics of shelterwood felling during which one – usually shade-tolerant tree species dominates in the natural regeneration (e.g. beech.

  3. Exploratory study of the effects of wing-leading-edge modifications on the stall/spin behavior of a light general aviation airplane

    Science.gov (United States)

    1979-01-01

    Configurations with full-span and segmented leading-edge flaps and full-span and segmented leading-edge droop were tested. Studies were conducted with wind-tunnel models, with an outdoor radio-controlled model, and with a full-scale airplane. Results show that wing-leading-edge modifications can produce large effects on stall/spin characteristics, particularly on spin resistance. One outboard wing-leading-edge modification tested significantly improved lateral stability at stall, spin resistance, and developed spin characteristics.

  4. Edge effects resulting from forest fragmentation enhance carbon uptake and its vulnerability to climate change in temperate broadleaf forests

    Science.gov (United States)

    Reinmann, A.; Hutyra, L.

    2016-12-01

    Forest fragmentation resulting from land use and land cover change is a ubiquitous, ongoing global phenomenon with profound impacts on the growing conditions of the world's remaining forest. However, our understanding of forest carbon dynamics and their response to climate largely comes from unfragmented forest systems, which presents an important mismatch between the landscapes we study and those we aim to characterize. The temperate broadleaf forest makes a large contribution to the global terrestrial carbon sink, but is also the most heavily fragmented forest biome in the world. We use field measurements and geospatial analyses to characterize carbon dynamics in temperate broadleaf forest fragments. We show that forest growth and biomass increase by 89 ± 17% and 64 ± 12%, respectively, from the forest interior to edge. These ecosystem edge enhancements are not currently captured by models or approaches to quantifying regional C balance, but across southern New England, USA it increases carbon uptake and storage by 12.5 ± 2.9% and 9.6 ± 1.4%, respectively. However, we also find that forest growth near the edge declines three times faster than in the interior in response to heat stress during the growing season. Using climate projections, we show that future heat stress could reduce the forest edge growth enhancement by one-third by the end of the century. These findings contrast studies of edge effects in the world's other major forest biomes and indicate that the strength of the temperate broadleaf forest carbon sink and its capacity to mitigate anthropogenic carbon emissions may be stronger, but also more sensitive to climate change than previous estimates suggest.

  5. Effects of microhabitat on leaf traits in Digitalis grandiflora L. (Veronicaceae growing at forest edge and interior

    Directory of Open Access Journals (Sweden)

    Kołodziejek J.

    2014-01-01

    Full Text Available The morphological, anatomical and biochemical traits of the leaves of yellow foxglove (Digitalis grandiflora Mill. from two microhabitats, forest interior (full shade under oak canopy and forest edge (half shade near shrubs, were studied. The microhabitats differed in the mean levels of available light, but did not differ in soil moisture. The mean level of light in the forest edge microhabitat was significantly higher than in the forest interior. Multivariate ANOVA was used to test the effects of microhabitat. Comparison of the available light with soil moisture revealed that both factors significantly influenced the morphological and anatomical variables of D. grandiflora. Leaf area, mass, leaf mass per area (LMA, surface area per unit dry mass (SLA, density and thickness varied greatly between leaves exposed to different light regimes. Leaves that developed in the shade were larger and thinner and had a greater SLA than those that developed in the half shade. In contrast, at higher light irradiances, at the forest edge, leaves tended to be thicker, with higher LMA and density. Stomatal density was higher in the half-shade leaves than in the full-shade ones. LMA was correlated with leaf area and mass and to a lesser extent with thickness and density in the forest edge microsite. The considerable variations in leaf density and thickness recorded here confirm the very high variation in cell size and amounts of structural tissue within species. The leaf plasticity index (PI was the highest for the morphological leaf traits as compared to the anatomical and biochemical ones. The nitrogen content was higher in the “half-shade leaves” than in the “shade leaves”. Denser leaves corresponded to lower nitrogen (N contents. The leaves of plants from the forest edge had more potassium (K than leaves of plants from the forest interior on an area basis but not on a dry mass basis; the reverse was true for phosphorus.

  6. Increased Back-Bonding Explains Step-Edge Reactivity and Particle Size Effect for CO Activation on Ru Nanoparticles.

    Science.gov (United States)

    Foppa, Lucas; Copéret, Christophe; Comas-Vives, Aleix

    2016-12-28

    Carbon monoxide is a ubiquitous molecule, a key feedstock and intermediate in chemical processes. Its adsorption and activation, typically carried out on metallic nanoparticles (NPs), are strongly dependent on the particle size. In particular, small NPs, which in principle contain more corner and step-edge atoms, are surprisingly less reactive than larger ones. Hereby, first-principles calculations on explicit Ru NP models (1-2 nm) show that both small and large NPs can present step-edge sites (e.g., B 5 and B 6 sites). However, such sites display strong particle-size-dependent reactivity because of very subtle differences in local chemical bonding. State-of-the-art crystal orbital Hamilton population analysis allows a detailed molecular orbital picture of adsorbed CO on step-edges, which can be classified as flat (η 1 coordination) and concave (η 2 coordination) sites. Our analysis shows that the CO π-metal d π hybrid band responsible for the electron back-donation is better represented by an oxygen lone pair on flat sites, whereas it is delocalized on both C and O atoms on concave sites, increasing the back-bonding on these sites compared to flat step-edges or low-index surface sites. The bonding analysis also rationalizes why CO cleavage is easier on step-edge sites of large NPs compared to small ones irrespective of the site geometry. The lower reactivity of small NPs is due to the smaller extent of the Ru-O interaction in the η 2 adsorption mode, which destabilizes the η 2 transition-state structure for CO direct cleavage. Our findings provide a molecular understanding of the reactivity of CO on NPs, which is consistent with the observed particle size effect.

  7. The effect of seated pelvic tilt on posterior edge-loading in total hip arthroplasty: A finite element investigation.

    Science.gov (United States)

    Pierrepont, Jim; Yang, Long; Arulampalam, Jevan; Stambouzou, Catherine; Miles, Brad; Li, Qing

    2018-03-01

    Edge-loading of a ceramic-on-ceramic total hip replacement can lead to reproducible squeaking and revision. A patient's functional acetabular cup orientation, driven by their pelvic tilt, has been shown to be a significant factor in squeaking during hip flexion. The aim of this study was to investigate the effect of seated pelvic tilt on the contact mechanics at the ceramic bearing surface. A finite element model of a ceramic-on-ceramic total hip replacement was created. The cup was orientated at 40° inclination and 15° anteversion relative to the anterior pelvic plane. The stem was flexed 90° to replicate sitting in a chair. The model was loaded using data from in vivo measurements taken during a sit-to-stand activity. The pelvis was modelled in seven different sagittal positions, ranging from -30° to 30° of pelvic tilt, where a positive value denotes anterior pelvic tilt. Three different head sizes were investigated: 32, 36 and 40 mm. The maximum contact pressure and contact patch to rim distance were determined for each of the 21 simulations. Edge-loading (contact patch to rim distance Edge-loading initiated at seated pelvic tilts of 7°, 9° and 5° for the 32, 36 and 40 mm heads, respectively. Patients with anterior pelvic tilts in the seated position are susceptible to posterior edge-loading. As the position of the pelvis when seated is patient specific, cup orientation should be adjusted on an individual basis to minimise edge-loading.

  8. Facebook and its effects on users' empathic social skills and life satisfaction: a double-edged sword effect.

    Science.gov (United States)

    Chan, Terri H

    2014-05-01

    This study examines how Facebook usage affects individual's empathic social skills and life satisfaction. Following the self-presentational theory, the study explores a key component of the Internet paradox-whether Facebook suppresses or enhances users' interpersonal competence (specifically empathic social skills), given their respective personality makeup. Going further, the study assesses these events' subsequent impacts on users' psychological well-being. Analogous to a double-edged sword, Facebook activities are hypothesized to suppress the positive effect of a user's extraversion orientation on empathic social skills but lessen the negative effect of neuroticism on these skills. The study examines a sample of college-aged Facebook users (n=515), who responded to a large-scale online survey. The findings from a structural equation modeling analysis indicate that while empathic social skills are positively associated with life satisfaction, Facebook activities mainly exert suppression effects. Only upon low usage can Facebook activities lessen the negative effect of neuroticism on empathic social skills, suggesting that Facebook may appear as a less threatening platform for social interactions among neurotics. Yet, results in general suggest that undesirable effects may occur at high levels of Facebook usage whereby both extroverted and neurotic users displace real world social ties to online ones. The findings point to the complex ways in which social media usage may impact the livelihood of users.

  9. Wild Pigs (Sus scrofa) Mediate Large-Scale Edge Effects in a Lowland Tropical Rainforest in Peninsular Malaysia

    OpenAIRE

    Fujinuma, Junichi; Harrison, Rhett D.

    2012-01-01

    Edge-effects greatly extend the area of tropical forests degraded through human activities. At Pasoh, Peninsular Malaysia, it has been suggested that soil disturbance by highly abundant wild pigs (Sus scrofa), which feed in adjacent Oil Palm plantations, may have mediated the invasion of Clidemia hirta (Melastomataceae) into the diverse tropical lowland rain forest. To investigate this hypothesis, we established three 1 km transects from the forest/Oil Palm plantation boundary into the forest...

  10. Strong influence of long-distance edge effect on herb-layer vegetation in forest fragments in an agricultural landscape

    Czech Academy of Sciences Publication Activity Database

    Hofmeister, J.; Hošek, J.; Brabec, Marek; Hédl, Radim; Modrý, M.

    2013-01-01

    Roč. 15, č. 6 (2013), s. 293-303 ISSN 1433-8319 Grant - others:GA MŽP(CZ) SM/6/69/05; GA MŽP(CZ) SP/2D3/139/07 Institutional support: RVO:67985807 ; RVO:67985939 Keywords : ancient forest * edge effect * habitat fragmentation * light condition * soil nutrients * species richness Subject RIV: BB - Applied Statistics, Operational Research; EH - Ecology, Behaviour (BU-J) Impact factor: 3.324, year: 2013

  11. Effect of cutting edge preparation on tool performance in hard-turning of DF-3 tool steel with ceramic tools

    International Nuclear Information System (INIS)

    Davoudinejad, A.; Noordin, M. Y.

    2014-01-01

    This study presents an experimental investigation on turning hardened DF-3 tool steel (∼ 58HRC) with PVD-TiN coated mixed ceramic. We focused on the effect of chamfer and honed edge geometry on tool wear, tool life, cutting forces and surface finish of the machined work piece. The effects of the process parameters on performance characteristics were investigated using ANOVA. It was found that longer tool life was recorded with chamfered edge geometry at various cutting conditions. The typical damage observed as flank and crater wear for ceramic tools and abrasive wear was found as the main mechanism.The optimal cutting speed was 155 m/min, with which a tolerable tool life and volume of material removal was obtained for both edges geometry. Finer machined surface was left by chamfered tool with feeds and speeds in the range of 0.125-0.05 mm/rev and 155-210 m/min, respectively; also, cutting forces decrease with increased cutting speed. The obtained consequence of cutting forces shows that tool wear has a considerable effect on cutting forces and greater forces values recorded with honed tools.

  12. Effect of cutting edge preparation on tool performance in hard-turning of DF-3 tool steel with ceramic tools

    Energy Technology Data Exchange (ETDEWEB)

    Davoudinejad, A.; Noordin, M. Y. [Universiti Teknologi Malaysia, Skudai (Malaysia)

    2014-11-15

    This study presents an experimental investigation on turning hardened DF-3 tool steel (∼ 58HRC) with PVD-TiN coated mixed ceramic. We focused on the effect of chamfer and honed edge geometry on tool wear, tool life, cutting forces and surface finish of the machined work piece. The effects of the process parameters on performance characteristics were investigated using ANOVA. It was found that longer tool life was recorded with chamfered edge geometry at various cutting conditions. The typical damage observed as flank and crater wear for ceramic tools and abrasive wear was found as the main mechanism.The optimal cutting speed was 155 m/min, with which a tolerable tool life and volume of material removal was obtained for both edges geometry. Finer machined surface was left by chamfered tool with feeds and speeds in the range of 0.125-0.05 mm/rev and 155-210 m/min, respectively; also, cutting forces decrease with increased cutting speed. The obtained consequence of cutting forces shows that tool wear has a considerable effect on cutting forces and greater forces values recorded with honed tools.

  13. Time evolution of the energy confinement time, internal inductance and effective edge safety factor on IR-T1 tokamak

    International Nuclear Information System (INIS)

    Salar Elahi, A; Ghoranneviss, M

    2010-01-01

    An attempt is made to investigate the time evolution of the energy confinement time, internal inductance and effective edge safety factor on IR-T1 tokamak. For this purpose, four magnetic pickup coils were designed, constructed and installed on the outer surface of the IR-T1 and then the Shafranov parameter (asymmetry factor) was obtained from them. On the other hand, also a diamagnetic loop was designed and installed on IR-T1 and poloidal beta was determined from it. Therefore, the internal inductance and effective edge safety factor were measured. Also, the time evolution of the energy confinement time was measured using the diamagnetic loop. Experimental results on IR-T1 show that the maximum energy confinement time (which corresponds to minimum collisions, minimum microinstabilities and minimum transport) is at low values of the effective edge safety factor (2.5 eff (a) i <0.72). The results obtained are in agreement with those obtained with the theoretical approach [1-5].

  14. Experimental investigation of edge sheared flow development and configuration effects in the TJ-II stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Pedrosa, M. A.; Hidalgo, C.; Alonso, A.; Calderon, E.; Orozco, R. O.; Pablos, J. L. de

    2005-07-01

    It is well known the importance of the shear as a stabilizing mechanism to control plasma fluctuations in magnetically confined plasmas [1]. It has been clearly established that Ex B shear stabilization mechanisms are an important piece for the improvement of confinement on fusion devices. In particular both edge and core transport barriers are related to a large increase in the Ex B sheared flow. As a consequence clarifying the driving mechanisms of sheared flow in fusion plasmas is a main issue. The existence of parallel and perpendicular sheared flows at the plasma edge, and the interplay between them in different plasma conditions has been studied in the TJ-II [2]. Recent experiments carried out by means of different approaches in the TJ-II stellarator have shown that the generation of spontaneous edge perpendicular sheared flow can be externally controlled by means of plasma density with good reproducibility and reliability [3, 4]. Although experimentally the plasma density has been used as an external control knob, it would be more appropriate to characterize experimental results in terms of edge plasma gradient (e.g. ion saturation current gradient) [3]. It has also been found that there exists a coupling between the onset of sheared flow development and an increase in the level of plasma edge turbulence; once sheared flow is fully developed the level of fluctuations and turbulent transport slightly decreases whereas edge gradients and plasma density increase. It has been experimentally established that the minimum plasma density (or/and minimum level of plasma turbulence) essential for the development of the shear layer depends on the plasma magnetic configuration [5, 6]. For some plasma magnetic configurations with high iota value a sheared flow-induced regime with characteristics resembling those of an improved confinement one has been found. The similarity in the structure of the velocity shear layer and in the turbulence characteristics [7] in different

  15. Simulated Nano scale Peeling Process of Monolayer Graphene Sheet: Effect of Edge Structure and Lifting Position

    International Nuclear Information System (INIS)

    Sasaki, N.; Okamoto, H.; Masuda, S.; Itamura, N.; Miura, K.

    2010-01-01

    The nanoscale peeling of the graphene sheet on the graphite surface is numerically studied by molecular mechanics simulation. For center-lifting case, the successive partial peelings of the graphene around the lifting center appear as discrete jumps in the force curve, which induce the arched deformation of the graphene sheet. For edge-lifting case, marked atomic-scale friction of the graphene sheet during the nanoscale peeling process is found. During the surface contact, the graphene sheet takes the atomic-scale sliding motion. The period of the peeling force curve during the surface contact decreases to the lattice period of the graphite. During the line contact, the graphene sheet also takes the stick-slip sliding motion. These findings indicate the possibility of not only the direct observation of the atomic-scale friction of the graphene sheet at the tip/surface interface but also the identification of the lattice orientation and the edge structure of the graphene sheet.

  16. The stabilizing effect of core pressure on the edge pedestal in MAST plasmas

    International Nuclear Information System (INIS)

    Chapman, I.T.; Simpson, J.; Saarelma, S.; Kirk, A.; O'Gorman, T.; Scannell, R.

    2015-01-01

    The pedestal pressure measured in Mega Ampere Spherical Tokamak plasmas has been shown to increase as the global plasma pressure increases. By deliberately suppressing the transition into the high-confinement regime, the core plasma pressure was systematically altered at the time of the first edge localized mode. Stability analysis shows that the enhanced Shafranov shift at higher core pressure stabilizes the ballooning modes driven by the pedestal pressure gradient, consequently allowing the pedestal to reach higher pressures. (paper)

  17. On the effects of leading edge vortex generators on an OA209 airfoil

    OpenAIRE

    Heine, Benjamin; Mulleners, Karen; Gardner, Anthony; Mai, Holger

    2009-01-01

    Leading edge vortex generators have been found to significantly increase the aerodynamic performance of an airfoil under dynamic stall conditions. However, the principle of operation of these devices is still unclear. Therefore static wind and water tunnel experiments as well as CFD simulations have been conducted on a rotary aircraft wing profile OA209. A POD analysis applied to the vector fields generated by PIV measurements showed that the vortex generators break larger flow structures...

  18. Simulation study of CD variation caused by field edge effects and out-of-band radiation in EUVL

    Science.gov (United States)

    Gao, Weimin; Niroomand, Ardavan; Lorusso, Gian F.; Boone, Robert; Lucas, Kevin; Demmerle, Wolfgang

    2013-09-01

    Although extreme ultraviolet lithography (EUVL) remains a promising candidate for semiconductor device manufacturing of the 1x nm half pitch node and beyond, many technological burdens have to be overcome. The "field edge effect" in EUVL is one of them. The image border region of an EUV mask,also known as the "black border" (BB), reflects a few percent of the incident EUV light, resulting in a leakage of light into neighboring exposure fields, especially at the corner of the field where three adjacent exposures take place. This effect significantly impacts on CD uniformity (CDU) across the exposure field. To avoid this phenomenon, a light-shielding border is introduced by etching away the entire absorber and multi-layer (ML)at the image border region of the EUV mask. In this paper, we present a method of modeling the field edge effect (also called the BB effect) by using rigorous lithography simulation with a calibrated resist model. An additional "flare level" at the field edge is introduced on top of the exposure tool flare map to account for the BB effect. The parameters in this model include the reflectivity and the width of the BB, which are mainly determining the leakage of EUV light and its influence range, respectively. Another parameter is the transition width which represents the half shadow effect of the reticle masking blades. By setting the corresponding parameters, the simulation results match well the experimental results obtained at the imec's NXE:3100 EUV exposure tool. Moreover, these results indicate that the out-of-band (OoB) radiation also contributes to the CDU. Using simulation we can also determine the OoB effect rigorouslyusing the methodology of an "effective mask blank". The study in this paper demonstrates that the impact of BB and OoB effects on CDU can be well predicted by simulations.

  19. Photon-response spectrum of surface barrier diodes on GaAssub(1-x)Psub(x) mixed crystals

    International Nuclear Information System (INIS)

    Omar, O.A.

    1981-07-01

    Surface barrier diodes have been prepared by chemical deposition of thin gold film on samples of GaAssub(1-x)Psub(x) with x=0.3. The spectrum of the photo-response over a spectral range covering the photo-injection from the metal and the intrinsic absorption regions of the semiconductor has been measured. From the photo-threshold corresponding to each region, the height of the energy barrier and the forbidden gap width of the semiconductor have been determined and are found to be 0.96 e.v. and 1.78 e.v. respectively for the investigated composition. (author)

  20. Iridium Coating Deposited by Double Glow Plasma Technique — Effect of Glow Plasma on Structure of Coating at Single Substrate Edge

    International Nuclear Information System (INIS)

    Wu Wangping; Chen Zhaofeng; Liu Yong

    2012-01-01

    Double glow plasma technique has a high deposition rate for preparing iridium coating. However, the glow plasma can influence the structure of the coating at the single substrate edge. In this study, the iridium coating was prepared by double glow plasma on the surface of single niobium substrate. The microstructure of iridium coating at the substrate edge was observed by scanning electron microscopy. The composition of the coating was confirmed by energy dispersive spectroscopy and X-ray diffraction. There was a boundary between the coating and the substrate edge. The covered area for the iridium coating at the substrate edge became fewer and fewer from the inner area to the outer flange-area. The bamboo sprout-like particles on the surface of the substrate edge were composed of elemental niobium. The substrate edge was composed of the Nb coating and there was a transition zone between the Ir coating and the Nb coating. The interesting phenomenon of the substrate edge could be attributed to the effects of the bias voltages and the plasma cloud in the deposition chamber. The substrate edge effect could be mitigated or eliminated by adding lots of small niobium plates around the substrate in a deposition process. (plasma technology)

  1. Local shifts in floral biotic interactions in habitat edges and their effect on quantity and quality of plant offspring

    Science.gov (United States)

    Fenu, Giuseppe; Bernardo, Liliana

    2017-01-01

    Abstract Spatial shifts in insect fauna due to ecological heterogeneity can severely constrain plant reproduction. Nonetheless, data showing effects of insect visit patterns and intensity of mutualistic and/or antagonistic plant–insect interactions on plant reproduction over structured ecological gradients remain scarce. We investigated how changes in flower-visitor abundance, identity and behaviour over a forest-open habitat gradient affect plant biotic interactions, and quantitative and qualitative fitness in the edge-specialist Dianthus balbisii. Composition and behaviour of the insects visiting flowers of D. balbisii strongly varied over the study gradient, influencing strength and patterns of plant biotic interactions (i.e. herbivory and pollination likelihood). Seed set comparison in free- and manually pollinated flowers suggested spatial variations in the extent of quantitative pollen limitation, which appeared more pronounced at the gradient extremes. Such variations were congruent to patterns of flower visit and plant biotic interactions. The analyses on seed and seedling viability evidenced that spatial variation in amount and type of pollinators, and frequency of herbivory affected qualitative fitness of D. balbisii by influencing selfing and outcrossing rates. Our work emphasizes the role of plant biotic interactions as a fine-scale mediator of plant fitness in ecotones, highlighting that optimal plant reproduction can take place into a restricted interval of the ecological gradients occurring at forest edges. Reducing the habitat complexity typical of such transition contexts can threat edge-adapted plants. PMID:28775831

  2. Effects of Alternate Leading Edge Cutback on the Space Shuttle Main Engine Low Pressure Fuel Pump

    Science.gov (United States)

    Mulder, Andrew; Skelley, Stephen

    2016-01-01

    A higher order cavitation oscillation observed in the SSME low pressure fuel pump has been eliminated in water flow testing of a modified subscale replica of the inducer. The low pressure pump was modified by removing the outboard sections of two opposing blades of the four-bladed inducer, blending the "cutback" regions into the blades at the leading edge and tip, and removing material on the suction sides to decrease the exposed leading edge thickness. The leading edge tips of the cutback blades were moved approximately 25 degrees from their previous locations, thereby increasing one blade to blade spacing, decreasing the second, while simultaneously moving the cutback tips downstream. The test was conducted in MSFC's inducer test loop at scaled operating conditions in degassed and filtered water. In addition to eliminating HOC across the entire scaled operating regime, rotating cavitation was suppressed while the range of both alternate blade and asymmetric cavitation were increased. These latter phenomena, and more significantly, the shifts between these cavitation modes also resulted in significant changes to the head coefficient at low cavitation numbers. Reverse flow was detected at a slightly larger flow coefficient with the cutback inducer and suction capability was reduced by approximately 1 velocity head at and above approximately 90% of the reference flow coefficient. These performance changes along with more intense reverse flow are consistent with poor flow area management and increased incidence in the cutback region. Although the test demonstrated that the inducer modification was successful at eliminating the higher order cavitation across the entire scaled operating regime, different, previously unobserved, cavitation oscillations were introduced and significant performance penalties were imposed.

  3. Temperature measurement of flat glass edge during grinding and effect of wheel and workpiece speeds

    International Nuclear Information System (INIS)

    Moussa, Tala; Garnier, Bertrand; Peerhossaini, Hassan

    2017-01-01

    Flat glass temperature at the vicinity of the grinding wheel during grinding can become very high and reach that of the glass transition (typically around 550–600 °C). In such cases, the mechanical strength of glass is greatly affected and the grinding process cannot be carried out properly. Hence, thermal phenomena must be managed by adjusting the machining parameters to avoid overheating. For this purpose, it is very important to be able to measure the glass temperature, especially at the grinding interface. However, measuring the interfacial glass temperature is difficult and none of the existing methods for metal grinding is adequate for glass grinding. This work shows a novel temperature method that uses constantan and copper strips on both sides of the glass plates; thermoelectric contact being provided by the metallic binder of diamond particles in the grinding wheel. This new technique allows the measurement of the glass edge temperature during the wheel displacement around the glass plate. The experimental results show an average glass edge temperature between 300 and 600 °C depending on the value of the machining parameters such as work speed, wheel speed, depth of cut and water coolant flow rate. As this new thermal instrumentation is rather intrusive, glass temperature biases were analysed using a 3D heat transfer model with a moving source. Model computations performed using finite elements show that the temperature biases are less than 70 °C, which is smaller than the standard deviation of the glass edge temperatures measured during grinding. (paper)

  4. X transport and its effect on H-mode and edge pedestal in tokamaks

    International Nuclear Information System (INIS)

    Chang, C.S.; Darrow, D.; White, R.; Lin, Z.; Lee, W.; Ku, S.H.; Weitzner, H.; Carlstrom, T.N.; Grassie, J.S. de

    2001-01-01

    A new classical non-ambipolar transport mechanism has been identified which can be a dominant source of strong Er and edge pedestal layer formation immediately inside the separatrix in a diverted tokamak. Due to vanishingly small poloidal B-field and grad-B drift toward x-point, plasma ions with small ν parallel in the X-region do not have confined single particle orbits. This leads to a non-ambipolar convective transport in the X-region (X-transport), either collisional or collisionless, inducing a strong negative Er-shear layer. The X-transport can provide basic understanding of many of the experimental observations. (author)

  5. Analyses of edge effects on residual stresses in film strip/substrate systems

    International Nuclear Information System (INIS)

    Hsueh, Chun-Hway

    2000-01-01

    The residual stress distribution in a thin-film strip overlaid on a substrate is influenced by the edges of the strip. An analytical model is developed to derive a closed-form solution for the stress distribution along the film width. Because the film is much thinner than the substrate, the stress variation through the film thickness is ignored; however, the stress variation through the substrate thickness is considered in the analysis. Compared to the existing analytical models, the present model is more rigorous and the analytical results agree better with both finite element results and experimental measurements. (c) 2000 American Institute of Physics

  6. Edge Detection,

    Science.gov (United States)

    1985-09-01

    PROJECT. T ASK0 Artificial Inteligence Laboratory AREA It WORK UNIT NUMBERS V 545 Technology Square ( Cambridge, HA 02139 I I* CONTOOL1LIN@4OFFICE NAME...ARD-A1t62 62 EDGE DETECTION(U) NASSACNUSETTS INST OF TECH CAMBRIDGE 1/1 ARTIFICIAL INTELLIGENCE LAB E C HILDRETH SEP 85 AI-M-8 N99SI4-8S-C-6595...used to carry out this analysis. cce~iO a N) ’.~" D LI’BL. P p ------------ Sj. t i MASSACHUSETTS INSTITUTE OF TECHNOLOGY i ARTIFICIAL INTELLIGENCE

  7. Modeling hydrology and reactive transport in roads: The effect of cracks, the edge, and contaminant properties

    International Nuclear Information System (INIS)

    Apul, Defne S.; Gardner, Kevin H.; Eighmy, T. Taylor

    2007-01-01

    The goal of this research was to provide a tool for regulators to evaluate the groundwater contamination from the use of virgin and secondary materials in road construction. A finite element model, HYDRUS2D, was used to evaluate generic scenarios for secondary material use in base layers. Use of generic model results for particular applications was demonstrated through a steel slag example. The hydrology and reactive transport of contaminants were modeled in a two-dimensional cross section of a road. Model simulations showed that in an intact pavement, lateral velocities from the edge towards the centerline may transport contaminants in the base layer. The dominant transport mechanisms are advection closer to the edge and diffusion closer to the centerline. A shoulder joint in the pavement allows 0.03 to 0.45 m 3 /day of infiltration per meter of joint length as a function of the base and subgrade hydrology and the rain intensity. Scenario simulations showed that salts in the base layer of pavements are depleted by 99% in the first 20 years, whereas the metals may not reach the groundwater in 20 years at any significant concentrations if the pavement is built on adsorbing soils

  8. Edge gradient and safety factor effects on electrostatic turbulent transport in tokamaks

    International Nuclear Information System (INIS)

    Tan, Ing Hwie.

    1992-05-01

    Electrostatic turbulence and transport measurements are performed on the Tokapole-II tokamak at the University of Wisconsin-Madison, as the safety-factor and the edge equilibrium gradients and varied substantially. Tokapole-II is a poloidal divertor tokamak capable of operating at a wide range of safety factors due to its unique magnetic limiter configuration. It also has retractable material limiters in a large scrape-off region, which permits the study of edge boundary conditions like density and temperature gradients. The turbulence is independent of safety factor, but strongly sensitive to the local density gradient, which itself depends upon the limiter configuration. When a material limiter is inserted in a high discharge, the density gradient is increased locally together with a local increase of the turbulence. On the other hand, limiter insertion in low discharges did not increase the density gradient as much and the turbulence properties are unchanged with respect to the magnetic limiter case. It is conducted then, that electrostatic turbulence is caused by the density gradient. Although the electrostatic fluctuation driven transport is enhanced in the large density gradient case, it is in all cases to small to explain the observed energy confinement times. To explore instabilities with small wavelengths, a 0.5 mm diameter shperical Langmuir probe was constructed, and its power compared with the power measured by larger cylindrical probes

  9. Effects of interface edge configuration on residual stress in the bonded structures for a divertor application

    International Nuclear Information System (INIS)

    Kitamura, K.; Nagata, K.; Shibui, M.; Tachikawa, N.; Araki, M.

    1998-01-01

    Residual stresses in the interface region, that developed at the cool down during the brazing, were evaluated for several bonded structures to assess the mechanical strength of the bonded interface, using thermoelasto-plastic stress analysis. Normal stress components of the residual stresses around the interface edge of graphite-copper (C-Cu) bonded structures were compared for three types of bonded features such as flat-type, monoblock-type and saddle-type. The saddle-type structure was found to be favorable for its relatively low residual stress, easy fabrication accuracy on bonded interface and armor replacement. Residual stresses around the interface edge in three armor materials/copper bonded structures for a divertor plate were also examined for the C-Cu, tungsten-copper (W-Cu) and molybdenum alloy-copper (TZM-Cu), varying the interface wedge angle from 45 to 135 . An optimal bonded configuration for the least value of residual stress was found to have a wedge angle of 45 for the C-Cu, and 135 for both the W-Cu and TZM-Cu bonded ones. (orig.)

  10. Gust-Tunnel Investigation of the Effect of a Sharp-Edge Gust on the Flapwise Blade Bending Moments of a Model Helicopter Rotor

    National Research Council Canada - National Science Library

    Maglieri, Domenic

    1955-01-01

    Preliminary investigations have been made in the Langley gust tunnel to determine the effects of a sharp-edge vertical gust on the blade flapwise vibratory bending moments of small model rotors having...

  11. Effect of the X-point on the stability of the edge-current-driven MHD mode in Tokamaks

    International Nuclear Information System (INIS)

    Kwon, Ohjin

    2010-01-01

    Quasi-periodic bursts of edge magnetohydrodynamic (MHD) activities, called edge localized modes (ELMs), have been observed in many tokamaks during the H-mode. The high level of heat and particle transport associated with ELMs may cause serious damage to divertors or plasma facing components. It is therefore important to understand the underlying physics of ELMs. We have numerically investigated the effect of the X-point on the stability of the peeling mode, which is thought to be one of the MHD instabilities responsible for small ELMs. Equilibria with pressure and current profiles, which are unstable to the pure peeling mode for moderately elongated plasma, have been used. The X-point in a diverted plasma has been simulated by introducing of a hump in the plasma boundary. The position, depth and width of the X-point have been varied, and their effect on the stability of the peeling mode has been investigated. We have shown that the peeling mode growth rate decreases as the depth increases. This effect is greater for smaller widths for all positions of the X-point considered. Therefore, a sharper X-point is more efficient in stabilizing the peeling mode. Increasing the depth acts to increase the magnetic shear, the stabilizing effect of which has been shown to have very little dependence on the position or the width of the X-point.

  12. Effect of magnetic boundary on edge plasma profiles studied using probe measurements in EXTRAP T2R

    OpenAIRE

    Moustaphawi, Hawra

    2012-01-01

    In this Master’s thesis project, several experiments are conducted under three different conditions in order to study their effect on the edge plasma profiles. In the first case, the standard case, there is no external interference and the plasma is studied under normal lab environments. In the second case, the plasma position inside the EXTRAP T2R device is changed by a few millimeters and in the third case a magnetic boundary is inserted into the experiment. For each set of the experiment, ...

  13. Lithium line radiation in turbulent edge plasmas: Effects of low and high frequency temperature fluctuations

    Science.gov (United States)

    Rosato, J.; Capes, H.; Catoire, F.; Kadomtsev, M. B.; Levashova, M. G.; Lisitsa, V. S.; Marandet, Y.; Rosmej, F. B.; Stamm, R.

    2011-08-01

    In lithium-wall-conditioned tokamaks, the line radiation due to the intrinsic impurities (Li/Li+/Li++) plays a significant role on the power balance. Calculations of the radiation losses are usually performed using a stationary collisional-radiative model, assuming constant values for the plasma parameters (Ne, Te,…). Such an approach is not suitable for turbulent plasmas where the various parameters are time-dependent. This is critical especially for the edge region, where the fluctuation rates can reach several tens of percents [e.g. J.A. Boedo, J. Nucl. Mater. 390-391 (2009) 29-37]. In this work, the role of turbulence on the radiated power is investigated with a statistical formalism. A special emphasis is devoted to the role of temperature fluctuations, successively for low-frequency fluctuations and in the general case where the characteristic turbulence frequencies can be comparable to the collisional and radiative rates.

  14. Supersymmetric Hamiltonian approach to edge excitations in ν=5/2 fractional quantum Hall effect

    International Nuclear Information System (INIS)

    Yu Ming; Zhang Xin

    2008-01-01

    A supersymmetric Hamiltonian is constructed for the edge excitations of the Moore-Read (Pfaffian) like state, which is a realization of the N=2 supersymmetric CS model. Fermionic generators and their conjugates are introduced to deal with the fermion pairing, whose condensation form a BCS like state. After Bogoliubov transformation, an N=2 supersymmetric and nonrelativistic Hamiltonian is found to take a known form, which is integrable. The main difference between the Moore-Read state and our BCS like state is that the number of fermion pairs in our formalism is not fixed. However, we have also found that the excited states in our model looks similar but not exactly the same as Moore and Read's

  15. Effect of dried sunflower seeds on incisal edge abrasion: A rare case report.

    Science.gov (United States)

    Rath, Avita; Ramamurthy, Priyadarshini H; Fernandes, Bennete Aloysius; Sidhu, Preena

    2017-01-01

    Tooth surface loss (TSL) is a complex phenomenon characterized by the loss of hard tooth structure at various locations of the teeth, usually due to more than one factor. TSL due to abrasion can be significant in patients consuming coarse, abrasive diet. The present case reports an interesting incisal edge abrasion in a female patient, attributed to a particular dietary behavior of long-term consumption of sunflower seeds. All her family members and most of the people from her native place were also reported to have similar lesions by the patient. Larger epidemiological studies to assess the prevalence and severity of such abrasive lesions in geographic areas with this particular dietary habit need to be carried out so that people may be made aware and educated about alternative ways of eating sunflower seeds that will not cause any form of tooth wear.

  16. Effect of low density H-mode operation on edge and divertor plasma parameters

    International Nuclear Information System (INIS)

    Maingi, R.; Mioduszewski, P.K.; Cuthbertson, J.W.

    1994-07-01

    We present a study of the impact of H-mode operation at low density on divertor plasma parameters on the DIII-D tokamak. The line-average density in H-mode was scanned by variation of the particle exhaust rate, using the recently installed divertor cryo-condensation pump. The maximum decrease (50%) in line-average electron density was accompanied by a factor of 2 increase in the edge electron temperature, and 10% and 20% reductions in the measured core and divertor radiated power, respectively. The measured total power to the inboard divertor target increased by a factor of 3, with the major contribution coming from a factor of 5 increase in the peak heat flux very close to the inner strike point. The measured increase in power at the inboard divertor target was approximately equal to the measured decrease in core and divertor radiation

  17. Effects of Rotation at Different Channel Orientations on the Flow Field inside a Trailing Edge Internal Cooling Channel

    Directory of Open Access Journals (Sweden)

    Matteo Pascotto

    2013-01-01

    Full Text Available The flow field inside a cooling channel for the trailing edge of gas turbine blades has been numerically investigated with the aim to highlight the effects of channel rotation and orientation. A commercial 3D RANS solver including a SST turbulence model has been used to compute the isothermal steady air flow inside both static and rotating passages. Simulations were performed at a Reynolds number equal to 20000, a rotation number (Ro of 0, 0.23, and 0.46, and channel orientations of γ=0∘, 22.5°, and 45°, extending previous results towards new engine-like working conditions. The numerical results have been carefully validated against experimental data obtained by the same authors for conditions γ=0∘ and Ro = 0, 0.23. Rotation effects are shown to alter significantly the flow field inside both inlet and trailing edge regions. These effects are attenuated by an increase of the channel orientation from γ=0∘ to 45°.

  18. Energy response of silicon surface barrier detector in view of charge collection process

    International Nuclear Information System (INIS)

    Kanno, Ikuo; Nishio, Katsuhisa; Inbe, Takashi; Kanazawa, Satoshi; Kimura, Itsuro

    1994-01-01

    In this report, the recombination effect is estimated. We take the recombination effect as the combined effect of the timing response and the energy response. With the establishment of the estimation method of the recombination effect, the consistency between the energy measurements and timing measurements will be judged. (J.P.N.)

  19. [Edge effect on lichen's distribution and chlorophyll content, in fragments of Polylepis quadrijuga (Rosaceae) in Páramo de la Rusia (Boyacá-Colombia)].

    Science.gov (United States)

    Pulido Herrera, Karen; Ramos Montaño, Carolina

    2016-12-01

    The ecosystems fragmentation is one of the anthropic phenomena with highest impact at global level and the edge effect causes that only the fragments interior conserve their original biotic and abiotic characteristics. Lichens are organisms especially susceptible to environmental variability, what could be useful for bio-indication of edge effect. In this work, we evaluated the edge effect in two fragments of Polylepis quadrijuga in the Páramo de la Rusia (Boyacá-Colombia) to determine if there is an edge effect on distribution of lichens associated to P. quadrijuga and their chlorophyll content. We used three transects of 70 m across the matrix-edge-interior gradient in each fragment. We chose nine phorophytes per transect to measure the environmental variables: photosynthetically active radiation, relative humidity and air temperature, and the biological variables: richness and cover per species. Besides, we employed the species that were present in all the three zones of the gradient to quantify the content of chlorophylls a and b, and determine if there are changes in the ratio of chlorophylls a/b that could suggest physiological plasticity as a response to the edge effect. Our results showed that fragment 2 had a higher edge exposition because of its high relation perimeter/area, allowing to an environmental homogenization and lose of biodiversity in relation with fragment 1. Overall, we found 55 differentially distributed species in relation with the fragments and the matrix-edge-interior gradient. The interior of fragment 1 was the most conserved zone, harboring a composition different in more than 40 % to the composition of any other zone. We classified the lichens according with their habits: gelatinous, fruticose, crusty or foliose, but we did not find any relationship between the habit distribution and the edge effect. Six species of wide distribution showed changes in the chlorophyll content along the matrix-edge-interior gradient, what is an evidence

  20. Molecular anisotropy effects in carbon K-edge scattering: depolarized diffuse scattering and optical anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Stone, Kevin H.

    2014-07-14

    Some polymer properties, such as conductivity, are very sensitive to short- and intermediate-range orientational and positional ordering of anisotropic molecular functional groups, and yet means to characterize orientational order in disordered systems are very limited. We demonstrate that resonant scattering at the carbon K-edge is uniquely sensitive to short-range orientation correlations in polymers through depolarized scattering at high momentum transfers, using atactic polystyrene as a well-characterized test system. Depolarized scattering is found to coexist with unpolarized fluorescence, and to exhibit pronounced anisotropy. We also quantify the spatially averaged optical anisotropy from low-angle reflectivity measurements, finding anisotropy consistent with prior visible, x-ray absorption, and theoretical studies. The average anisotropy is much smaller than that in the depolarized scattering and the two have different character. Both measurements exhibit clear spectral signatures from the phenyl rings and the polyethylene-like backbone. Discussion focuses on analysis considerations and prospects for using this depolarized scattering for studies of disorder in soft condensed matter.

  1. Lithium line radiation in turbulent edge plasmas: Effects of low and high frequency temperature fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Rosato, J., E-mail: joel.rosato@univ-provence.fr [PIIM, UMR 6633, Universite de Provence/CNRS, Centre de St.-Jerome, Case 232, F-13397 Marseille Cedex 20 (France); Capes, H.; Catoire, F. [PIIM, UMR 6633, Universite de Provence/CNRS, Centre de St.-Jerome, Case 232, F-13397 Marseille Cedex 20 (France); Kadomtsev, M.B.; Levashova, M.G.; Lisitsa, V.S. [ITP, Russian Research Center ' Kurchatov Institute' , Moscow (Russian Federation); Marandet, Y. [PIIM, UMR 6633, Universite de Provence/CNRS, Centre de St.-Jerome, Case 232, F-13397 Marseille Cedex 20 (France); Rosmej, F.B. [LULI, UMR 7605, Universite Pierre et Marie Curie/CNRS, 4 Place Jussieu, Case 128, F-75252 Paris Cedex 05 (France); Stamm, R. [PIIM, UMR 6633, Universite de Provence/CNRS, Centre de St.-Jerome, Case 232, F-13397 Marseille Cedex 20 (France)

    2011-08-01

    In lithium-wall-conditioned tokamaks, the line radiation due to the intrinsic impurities (Li/Li{sup +}/Li{sup ++}) plays a significant role on the power balance. Calculations of the radiation losses are usually performed using a stationary collisional-radiative model, assuming constant values for the plasma parameters (N{sub e}, T{sub e},...). Such an approach is not suitable for turbulent plasmas where the various parameters are time-dependent. This is critical especially for the edge region, where the fluctuation rates can reach several tens of percents [e.g. J.A. Boedo, J. Nucl. Mater. 390-391 (2009) 29-37]. In this work, the role of turbulence on the radiated power is investigated with a statistical formalism. A special emphasis is devoted to the role of temperature fluctuations, successively for low-frequency fluctuations and in the general case where the characteristic turbulence frequencies can be comparable to the collisional and radiative rates.

  2. Effect of sputtered lanthanum hexaboride film thickness on field emission from metallic knife edge cathodes

    Science.gov (United States)

    Kirley, M. P.; Novakovic, B.; Sule, N.; Weber, M. J.; Knezevic, I.; Booske, J. H.

    2012-03-01

    We report experiments and analysis of field emission from metallic knife-edge cathodes, which are sputter-coated with thin films of lanthanum hexaboride (LaB6), a low-work function material. The emission current is found to depend sensitively on the thickness of the LaB6 layer. We find that films thinner than 10 nm greatly enhance the emitted current. However, cathodes coated with a thicker layer of LaB6 are observed to emit less current than the uncoated metallic cathode. This result is unexpected due to the higher work function of the bare metal cathode. We show, based on numerical calculation of the electrostatic potential throughout the structure, that the external (LaB6/vacuum) barrier is reduced with respect to uncoated samples for both thin and thick coatings. However, this behavior is not exhibited at the internal (metal/LaB6) barrier. In thinly coated samples, electrons tunnel efficiently through both the internal and external barrier, resulting in current enhancement with respect to the uncoated case. In contrast, the thick internal barrier in thickly coated samples suppresses current below the value for uncoated samples in spite of the lowered external barrier. We argue that this coating thickness variation stems from a relatively low (no higher than 1018 cm-3) free carrier density in the sputtered polycrystalline LaB6.

  3. Cutting Edge Localisation in an Edge Profile Milling Head

    NARCIS (Netherlands)

    Fernandez Robles, Laura; Azzopardi, George; Alegre, Enrique; Petkov, Nicolai

    2015-01-01

    Wear evaluation of cutting tools is a key issue for prolonging their lifetime and ensuring high quality of products. In this paper, we present a method for the effective localisation of cutting edges of inserts in digital images of an edge profile milling head. We introduce a new image data set of

  4. Using the fluorescence red edge effect to assess the long-term stability of lyophilized protein formulations.

    Science.gov (United States)

    Qian, Ken K; Grobelny, Pawel J; Tyagi, Madhusudan; Cicerone, Marcus T

    2015-04-06

    Nanosecond relaxation processes in sugar matrices are causally linked through diffusional processes to protein stability in lyophilized formulations. Long-term protein degradation rates track mean-squared displacement (⟨u(2)⟩) of hydrogen atoms in sugar glasses, a parameter describing dynamics on a time scale of picoseconds to nanoseconds. However, measurements of ⟨u(2)⟩ are usually performed by neutron scattering, which is not conducive to rapid formulation screening in early development. Here, we present a benchtop technique to derive a ⟨u(2)⟩ surrogate based on the fluorescence red edge effect. Glycerol, lyophilized trehalose, and lyophilized sucrose were used as model systems. Samples containing 10(-6) mole fraction of rhodamine 6G, a fluorophore, were excited at either 532 nm (main peak) or 566 nm (red edge), and the ⟨u(2)⟩ surrogate was determined based the corresponding Stokes shifts. Results showed reasonable agreement between ⟨u(2)⟩ from neutron scattering and the surrogate from fluorescence, although deviations were observed at very low temperatures. We discuss the sources of the deviations and suggest technique improvements to ameliorate these. We expect that this method will be a valuable tool to evaluate lyophilized sugar matrices with respect to their ability to protect proteins from diffusion-limited degradation processes during long-term storage. Additionally, the method may have broader applications in amorphous pharmaceutical solids.

  5. [Edge effects of forest gap in Pinus massoniana plantations on the decomposition of leaf litter recalcitrant components of Cinnamomum camphora and Toona ciliata.

    Science.gov (United States)

    Zhang, Yan; Zhang, Dan Ju; Li, Xun; Liu, Hua; Zhang, Ming Jin; Yang, Wan Qin; Zhang, Jian

    2016-04-22

    The objective of the study was to evaluate the dynamics of recalcitrant components during foliar litter decomposition under edge effects of forest gap in Pinus massoniana plantations in the low hilly land, Sichuan basin. A field litterbag experiment was conducted in seven forest gaps with different sizes (100, 225, 400, 625, 900, 1225, 1600 m 2 ) which were generated by thinning P. massoniana plantations. The degradation rate of four recalcitrant components, i.e., condensed tannins, total phenol, lignin and cellulose in foliar litter of two native species (Cinnamomum camphora and Toona ciliata) at the gap edge and under the closed canopy were measured. The results showed that the degradation rate of recalcitrant components in T. ciliata litter except for cellulose at the gap edge were significantly higher than that under the closed canopy. For C. camphora litter, only the degradation of lignin at the gap edge was higher than that under the closed canopy. After one-year decomposition, four recalcitrant components in two types of foliar litter exhibited an increment of degradation rate, and the degradation rate of condensed tannin was the fastest, followed by total phenol and cellulose, but the lignin degradation rate was the slowest. With the increase of gap size, except for cellulose, the degradation rate ofthe other three recalcitrant components of the T. ciliata at the edge of medium sized gaps (400 and 625 m 2 ) were significantly higher than at the edge of other gaps. However, lignin in the C. camphora litter at the 625 m 2 gap edge showed the greatest degradation rate. Both temperature and litter initial content were significantly correlated with litter recalcitrant component degradation. Our results suggested that medium sized gaps (400-625 m 2 ) had a more significant edge effect on the degradation of litter recalcitrant components in the two native species in P. massoniana plantations, however, the effect also depended on species.

  6. Adjustment of Sentinel-2 Multi-Spectral Instrument (MSI) Red-Edge Band Reflectance to Nadir BRDF Adjusted Reflectance (NBAR) and Quantification of Red-Edge Band BRDF Effects

    OpenAIRE

    David P. Roy; Zhongbin Li; Hankui K. Zhang

    2017-01-01

    Optical wavelength satellite data have directional reflectance effects over non-Lambertian surfaces, described by the bidirectional reflectance distribution function (BRDF). The Sentinel-2 multi-spectral instrument (MSI) acquires data over a 20.6° field of view that have been shown to have non-negligible BRDF effects in the visible, near-infrared, and short wave infrared bands. MSI red-edge BRDF effects have not been investigated. In this study, they are quantified by an examination of 6.6 mi...

  7. An application of the edge effect in measuring accessibility to multiple food retailer types in Southwestern Ontario, Canada

    Science.gov (United States)

    2011-01-01

    Background Trends in food retailing associated with the consolidation of smaller-format retailers into fewer, larger-format supercentres have left some rural areas with fewer sources of nutritious, affordable food. Access to nutritious, affordable food is essential for good dietary habits and combating health issues such as type-2 diabetes, obesity, and cardiovascular disease. Many studies on food environments use inaccurate or incomplete methods for locating food retailers, which may be responsible for mischaracterising food deserts. This study uses databases of every residence in and every food retailer in and around Middlesex County, Ontario, Canada. Residences were geocoded to their precise address, and network analysis techniques were performed in a geographic information system (GIS) to determine distances between every residence and different types of food retailers (grocery stores, fast food, fruit and vegetable sources, grocery stores plus fruit and vegetable sources, variety stores), both when considering and neglecting facilities outside the area of study, to account for a deficiency in analysis termed the 'edge effect'. Results Analysis of household accessibility to food outlets by neighbourhood socioeconomic distress level indicated that residents in the most distressed neighbourhoods tended to have better accessibility to all types of food retailers. In the most distressed neighbourhoods, 79 percent of residences were within walking distance of a grocery store, compared to only 10 percent in the least distressed neighbourhoods. When the edge effect was neglected, 37 percent of distance estimates proved inaccurate. Average accessibility to all food retailer types improved dramatically when food outlets adjacent to the study area were considered, thereby controlling for the edge effect. Conclusion By neglecting to consider food retailers just outside study area boundaries, previous studies may significantly over-report the actual distance necessary to

  8. An application of the edge effect in measuring accessibility to multiple food retailer types in southwestern Ontario, Canada.

    Science.gov (United States)

    Sadler, Richard C; Gilliland, Jason A; Arku, Godwin

    2011-05-15

    Trends in food retailing associated with the consolidation of smaller-format retailers into fewer, larger-format supercentres have left some rural areas with fewer sources of nutritious, affordable food. Access to nutritious, affordable food is essential for good dietary habits and combating health issues such as type-2 diabetes, obesity, and cardiovascular disease. Many studies on food environments use inaccurate or incomplete methods for locating food retailers, which may be responsible for mischaracterising food deserts. This study uses databases of every residence in and every food retailer in and around Middlesex County, Ontario, Canada. Residences were geocoded to their precise address, and network analysis techniques were performed in a geographic information system (GIS) to determine distances between every residence and different types of food retailers (grocery stores, fast food, fruit and vegetable sources, grocery stores plus fruit and vegetable sources, variety stores), both when considering and neglecting facilities outside the area of study, to account for a deficiency in analysis termed the 'edge effect'. Analysis of household accessibility to food outlets by neighbourhood socioeconomic distress level indicated that residents in the most distressed neighbourhoods tended to have better accessibility to all types of food retailers. In the most distressed neighbourhoods, 79 percent of residences were within walking distance of a grocery store, compared to only 10 percent in the least distressed neighbourhoods. When the edge effect was neglected, 37 percent of distance estimates proved inaccurate. Average accessibility to all food retailer types improved dramatically when food outlets adjacent to the study area were considered, thereby controlling for the edge effect. By neglecting to consider food retailers just outside study area boundaries, previous studies may significantly over-report the actual distance necessary to travel for food. Research on

  9. An application of the edge effect in measuring accessibility to multiple food retailer types in Southwestern Ontario, Canada

    Directory of Open Access Journals (Sweden)

    Arku Godwin

    2011-05-01

    Full Text Available Abstract Background Trends in food retailing associated with the consolidation of smaller-format retailers into fewer, larger-format supercentres have left some rural areas with fewer sources of nutritious, affordable food. Access to nutritious, affordable food is essential for good dietary habits and combating health issues such as type-2 diabetes, obesity, and cardiovascular disease. Many studies on food environments use inaccurate or incomplete methods for locating food retailers, which may be responsible for mischaracterising food deserts. This study uses databases of every residence in and every food retailer in and around Middlesex County, Ontario, Canada. Residences were geocoded to their precise address, and network analysis techniques were performed in a geographic information system (GIS to determine distances between every residence and different types of food retailers (grocery stores, fast food, fruit and vegetable sources, grocery stores plus fruit and vegetable sources, variety stores, both when considering and neglecting facilities outside the area of study, to account for a deficiency in analysis termed the 'edge effect'. Results Analysis of household accessibility to food outlets by neighbourhood socioeconomic distress level indicated that residents in the most distressed neighbourhoods tended to have better accessibility to all types of food retailers. In the most distressed neighbourhoods, 79 percent of residences were within walking distance of a grocery store, compared to only 10 percent in the least distressed neighbourhoods. When the edge effect was neglected, 37 percent of distance estimates proved inaccurate. Average accessibility to all food retailer types improved dramatically when food outlets adjacent to the study area were considered, thereby controlling for the edge effect. Conclusion By neglecting to consider food retailers just outside study area boundaries, previous studies may significantly over-report the

  10. Measurement of the modulation transfer function of a charge-coupled device array by the combination of the self-imaging effect and slanted edge method.

    Science.gov (United States)

    Najafi, Sedigheh; Madanipour, Khosro

    2013-07-01

    In this paper, by a combination of the self-imaging effect for Ronchi gratings and the standard slanted edge modulation transfer function (MTF) measurement method for CCD cameras, the MTF of the CCD array without optics is measured. For this purpose, a Ronchi-type grating is illuminated by an expanded He-Ne laser. A self-image of the grating appears without optics on the CCD array that is located on the Talbot distance. The lines of the self-image of the grating are used as a slanted edge array. This method has all the advantages of the slanted edge method, and also since the array of the edge is ready, the total area of the CCD can be tested. The measured MTF is related to the CCD array without optics.

  11. Aerodynamic forces and flow structures of the leading edge vortex on a flapping wing considering ground effect

    International Nuclear Information System (INIS)

    Truong, Tien Van; Yoon, Kwang Joon; Byun, Doyoung; Kim, Min Jun; Park, Hoon Cheol

    2013-01-01

    The aim of this work is to provide an insight into the aerodynamic performance of the beetle during takeoff, which has been estimated in previous investigations. We employed a scaled-up electromechanical model flapping wing to measure the aerodynamic forces and the three-dimensional flow structures on the flapping wing. The ground effect on the unsteady forces and flow structures were also characterized. The dynamically scaled wing model could replicate the general stroke pattern of the beetle's hind wing kinematics during takeoff flight. Two wing kinematic models have been studied to examine the influences of wing kinematics on unsteady aerodynamic forces. In the first model, the angle of attack is asymmetric and varies during the translational motion, which is the flapping motion of the beetle's hind wing. In the second model, the angle of attack is constant during the translational motion. The instantaneous aerodynamic forces were measured for four strokes during the beetle's takeoff by the force sensor attached at the wing base. Flow visualization provided a general picture of the evolution of the three-dimensional leading edge vortex (LEV) on the beetle hind wing model. The LEV is stable during each stroke, and increases radically from the root to the tip, forming a leading-edge spiral vortex. The force measurement results show that the vertical force generated by the hind wing is large enough to lift the beetle. For the beetle hind wing kinematics, the total vertical force production increases 18.4% and 8.6% for the first and second strokes, respectively, due to the ground effect. However, for the model with a constant angle of attack during translation, the vertical force is reduced during the first stroke. During the third and fourth strokes, the ground effect is negligible for both wing kinematic patterns. This finding suggests that the beetle's flapping mechanism induces a ground effect that can efficiently lift its body from the ground during takeoff

  12. Free edge effects study in laminated composites using Digital Image Correlation: effect of material and geometrical singularities

    Directory of Open Access Journals (Sweden)

    Brieu M.

    2010-06-01

    Full Text Available Composite materials are today used for various industrial applications. However, delamination on free edges, where stress gradients are strong, still remain a problem. In the aim of a better understanding of such phenomenons, Digital Image Correlation (DIC measurements have been carried out on [(15n/-15n2]s laminates under uniaxial tensile strain. Three different composites with different mechanical properties and microstructure have been tested as well as two samples geometries: flat and with ply drop. Experimental results show high shear strain concentrations near 15°/-15° interlaminar interfaces on free edges which depend on material mechanical properties and microstructure and increase in the vicinity of a geometrical singularity.

  13. Investigation of the Effect of Tool Edge Geometry upon Cutting Variables, Tool Wear and Burr Formation Using Finite Element Simulation — A Progress Report

    Science.gov (United States)

    Sartkulvanich, Partchapol; Al-Zkeri, Ibrahim; Yen, Yung-Chang; Altan, Taylan

    2004-06-01

    This paper summarizes some of the progress made on FEM simulations of metal cutting processes conducted at the Engineering Research Center (ERC/NSM). Presented research focuses on the performance of various cutting edge geometries (hone and chamfer edges) for different tool materials and specifically on: 1) the effect of round and chamfer edge geometries on the cutting variables in machining carbon steels and 2) the effect of the edge hone size upon the flank wear and burr formation behavior in face milling of A356-T6 aluminum alloy. In the second task, an innovative design of edge preparation with varying hone size around the tool nose is also explored using FEM. In order to model three-dimensional conventional turning and face milling with two-dimensional orthogonal cutting simulations, 2D simulation cross-sections consisting of the cutting speed direction and chip flow direction are selected at different locations along the tool nose radius. Then the geometries of the hone and chamfer edges and their associated tool angles as well as uncut chip thickness are determined on these planes and employed in cutting simulations. The chip flow direction on the tool rake face are obtained by examining the wear grooves on the experimental inserts or estimated by using Oxley's approximation theory of oblique cutting. Simulation results are compared with the available experimental results (e.g. cutting forces) both qualitatively and quantitatively.

  14. Investigation of the effect of tool edge geometry upon cutting variables, tool wear and burr formation using finite element simulation - A progress report

    International Nuclear Information System (INIS)

    Sartkulvanich, Partchapol; Al-Zkeri, Ibrahim; Yen Yungchang; Altan, Taylan

    2004-01-01

    This paper summarizes some of the progress made on FEM simulations of metal cutting processes conducted at the Engineering Research Center (ERC/NSM). Presented research focuses on the performance of various cutting edge geometries (hone and chamfer edges) for different tool materials and specifically on: 1) the effect of round and chamfer edge geometries on the cutting variables in machining carbon steels and 2) the effect of the edge hone size upon the flank wear and burr formation behavior in face milling of A356-T6 aluminum alloy. In the second task, an innovative design of edge preparation with varying hone size around the tool nose is also explored using FEM.In order to model three-dimensional conventional turning and face milling with two-dimensional orthogonal cutting simulations, 2D simulation cross-sections consisting of the cutting speed direction and chip flow direction are selected at different locations along the tool nose radius. Then the geometries of the hone and chamfer edges and their associated tool angles as well as uncut chip thickness are determined on these planes and employed in cutting simulations. The chip flow direction on the tool rake face are obtained by examining the wear grooves on the experimental inserts or estimated by using Oxley's approximation theory of oblique cutting. Simulation results are compared with the available experimental results (e.g. cutting forces) both qualitatively and quantitatively

  15. Flow field analysis inside a gas turbine trailing edge cooling channel under static and rotating conditions: Effect of ribs

    International Nuclear Information System (INIS)

    Mucignat, C.; Armellini, A.; Casarsa, L.

    2013-01-01

    Highlights: • Detailed PIV and Stereo PIV investigation on a rotating test section. • Static channel: absence of guiding effect for inclined ribs. • Static channel: the ribs influence significantly the flow also at the trailing edge. • Rotating channel: opposite flow features with respect to the static case. • The analyzed flow features justify the previously observed thermal performances. -- Abstract: The present work is part of a wider research program which concerns the aero-thermal characterization of cooling channels for the trailing edge of gas turbine blades. The selected passage model is characterized by a trapezoidal cross-section of high aspect-ratio and coolant discharge at the blade tip and along the wedge-shaped trailing edge, where seven elongated pedestals are also installed. In this contribution, a new channel configuration provided with inclined ribs installed inside the radial development region is analyzed, extending the previous results and completing the already available data base, thus providing an overall review of the aero-thermal performance of the considered passage. The velocity field inside the channel was measured by means of 2D and Stereo-PIV techniques in multiple flow planes under static and rotating conditions. The tests were performed under engine similar conditions with respect to both Reynolds (Re = 20,000) and Rotation (Ro = 0, 0.23) numbers. Time averaged flow fields and velocity fluctuation data inside the stationary and rotating channels are analyzed and also critically compared with the data acquired without ribs. In this way the effects on the flow field induced by both rotation and ribs are clearly described. In particular, the ribs modify substantially both the flow field on the channel walls where they are installed and the 3D separation structures that surround the pedestals. If also rotation is taken into account, the relative flow field is characterized by a considerable guiding effect of the ribs coupled

  16. Blanking Clearance and Punch Velocity Effects on The Sheared Edge Characteristic in Micro-Blanking of Commercially Pure Copper Sheet

    OpenAIRE

    Didin Zakaria Lubis; Ichsan Ristiawan

    2017-01-01

    This study aims to identify the influences between clearance and punch velocity on the part edge quality of blanked parts. Experiments have been conducted using material copper, punch-die clearance and punch velocity variations. In order to determine the reachable punch-die clearance and punch velocity required for blanking. The quality of the part-edge characteristics shows that higher punch velocity and decreases clearance value can improve the part-edge quality, resulting in smaller burr h...

  17. Field effect transistors based on phosphorene nanoribbon with selective edge-adsorption: A first-principles study

    Science.gov (United States)

    Hu, Mengli; Yang, Zhixiong; Zhou, Wenzhe; Li, Aolin; Pan, Jiangling; Ouyang, Fangping

    2018-04-01

    By using density functional theory (DFT) and nonequilibrium Green's function (NEGF), field effect transistor (FET) based on zigzag shaped phosphorene nanoribbons (ZPNR) are investigated. The FETs are constructed with bare-edged ZPNRs as electrodes and H, Cl or OH adsorbed ZPNRs as channel. It is found FETs with the three kinds of channel show similar transport properties. The FET is p-type with a maximum current on/off ratio of 104 and a minimum off-current of 1 nA. The working mode of FETs is dependent on the parity of channel length. It can be either enhancement mode or depletion mode and the off-state current shows an even-odd oscillation. The current oscillations are interpreted with density of states (DOS) analysis and methods of evolution operator and tight-binding Hamiltonian. Operating mechanism of the designed FETs is also presented with projected local density of states and band diagrams.

  18. [Effects of highway on the vegetation species composition along a distance gradient from road edge in southeastern margin of Tengeer Desert].

    Science.gov (United States)

    Feng, Li; Li, Xin-Rong; Guo, Qun; Zhang, Jing-Guang; Zhang, Zhi-Shan

    2011-05-01

    Aimed to examine the effects of highway on the vegetation species composition in arid desert area, forty-eight transects perpendicular to the provincial highway 201 from Shapotou to Jing-tai in the southeastern margin of Tengger Desert were installed, with the vegetation species distribution along a distance gradient from the road edge investigated. The results showed that with increasing distance from the road edge, the species number, coverage, biomass, and alpha-diversity of herbaceous plants declined, but had no significant differences with the control beyond 5 m. Within 0-6 m to the road edge, the herbaceous plant height was greater than that of the control, but their density had less change. Within 0-2 m to the road edge, the species turnover rate of herbaceous plants was lower; at 2-5m, this rate was the highest; while beyond 10 m, the species composition of herbaceous plants was similar to that of the control. The herbaceous plant community at the road edge was dominated by gramineous plants, with the disturbance-tolerant species Pennisetum centrasiaticum, Chloris virgata, and Agropyron cristatum accounting for 68.6% of the total. C. virgata beyond 1 m to the road edge had a rapid decrease in its individual number and presence frequency, P. centrasiaticum and A. cristatum beyond 2 m also showed a similar trend, while the composite plants Artemisia capillaris and A. frigida beyond 2 m from the road edge had a rapid increase in its individual number, accounting for 70% of the herbaceous plants. At the road edge, the coverage and density of shrubs were significantly lower than those of the control, but the species composition had no significant difference.

  19. Cutting-edge technology for public health workforce training in comparative effectiveness research.

    Science.gov (United States)

    Salinas-Miranda, Abraham A; Nash, Michelle C; Salemi, Jason L; Mbah, Alfred K; Salihu, Hamisu M

    2013-06-01

    A critical mass of public health practitioners with expertise in analytic techniques and best practices in comparative effectiveness research is needed to fuel informed decisions and improve the quality of health care. The purpose of this case study is to describe the development and formative evaluation of a technology-enhanced comparative effectiveness research learning curriculum and to assess its potential utility to improve core comparative effectiveness research competencies among the public health workforce. Selected public health experts formed a multidisciplinary research collaborative and participated in the development and evaluation of a blended 15-week comprehensive e-comparative effectiveness research training program, which incorporated an array of health informatics technologies. Results indicate that research-based organizations can use a systematic, flexible, and rapid means of instructing their workforce using technology-enhanced authoring tools, learning management systems, survey research software, online communities of practice, and mobile communication for effective and creative comparative effectiveness research training of the public health workforce.

  20. Plasma treatment of detonation and HPHT nanodiamonds in diffuse coplanar surface barrier discharge in H.sub.2./sub./N.sub.2./sub. flow

    Czech Academy of Sciences Publication Activity Database

    Jirásek, Vít; Čech, J.; Kozak, Halyna; Artemenko, Anna; Černák, M.; Kromka, Alexander

    2016-01-01

    Roč. 213, č. 10 (2016), s. 2680-2686 ISSN 1862-6300 R&D Projects: GA ČR(CZ) GA14-04790S Institutional support: RVO:68378271 Keywords : amination * diamond * diffuse coplanar surface barrier discharge * nanomaterials * surface functionalization Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.775, year: 2016

  1. Effect of the van der Waals interaction on the electron energy-loss near edge structure theoretical calculation.

    Science.gov (United States)

    Katsukura, Hirotaka; Miyata, Tomohiro; Tomita, Kota; Mizoguchi, Teruyasu

    2017-07-01

    The effect of the van der Waals (vdW) interaction on the simulation of the electron energy-loss near edge structure (ELNES) by a first-principles band-structure calculation is reported. The effect of the vdW interaction is considered by the Tkatchenko-Scheffler scheme, and the change of the spectrum profile and the energy shift are discussed. We perform calculations on systems in the solid, liquid and gaseous states. The transition energy shifts to lower energy by approximately 0.1eV in the condensed (solid and liquid) systems by introducing the vdW effect into the calculation, whereas the energy shift in the gaseous models is negligible owing to the long intermolecular distance. We reveal that the vdW interaction exhibits a larger effect on the excited state than the ground state owing to the presence of an excited electron in the unoccupied band. Moreover, the vdW effect is found to depend on the local electron density and the molecular coordination. In addition, this study suggests that the detection of the vdW interactions exhibited within materials is possible by a very stable and high resolution observation. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Delocalization and occupancy effects of 5f orbitals in plutonium intermetallics using L3-edge resonant X-ray emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Booth, C. H.; Medling, S. A.; Jiang, Yu; Bauer, E. D.; Tobash, P. H.; Mitchell, J. N.; Veirs, D. K.; Wall, M. A.; Allen, P. G.; Kas, J. J.; Sokaras, D.; Nordlund, D.; Weng, T. -C.

    2014-06-24

    Although actinide (An) L3 -edge X-ray absorption near-edge structure (XANES) spectroscopy has been very effective in determining An oxidation states in insulating, ionically bonded materials, such as in certain coordination compounds and mineral systems, the technique fails in systems featuring more delocalized 5f orbitals, especially in metals. Recently, actinide L3-edge resonant X-ray emission spec- troscopy (RXES) has been shown to be an effective alternative. This technique is further demonstrated here using a parameterized partial unoccupied density of states method to quantify both occupancy and delocalization of the 5f orbital in ?-Pu, ?-Pu, PuCoGa5 , PuCoIn5 , and PuSb2. These new results, supported by FEFF calculations, highlight the effects of strong correlations on RXES spectra and the technique?s ability to differentiate between f-orbital occupation and delocalization.

  3. EFFECT OF THE B DRIFT DIRECTION ON PLASMA EDGE PROPERTIES AND THEL-H TRANSITION ON DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    T.N. CARLSTROM; R.J. GROEBNER; G.R. McKEE; R.A. MOYER; T.L. RHODES; J.C. ROST; G.D. PORTER X.Q. XU; W.M. NEVINS

    2002-07-01

    The power threshold for the L-H transition, P{sub TH}, is low when the ion {del}B drift is toward the X-point and increases significantly when it is away from the X-point. In order to study the cause of this effect, we have compared lower single-null (LSN) discharges with upper single-null (USN) discharges where the ion {del}B drift direction is down in both cases. Since many plasma parameters change with input power, we have made comparisons at the same power level (PTOT=2.3 MW). For these experiments, the LSN discharge is just below PTH (2.7 MW) and the USN discharge is far from P{sub TH} (6.8 MW). We have measured various properties of the edge plasma in an attempt to identify changes that may be responsible for the difference in P{sub TH} for the two cases. The equilibrium flux surfaces and diagnostic measurement locations are shown. The most pronounced difference is the reversal and the increased shear in the poloidal group velocity of the density fluctuations near the plasma edge [1]. These results complement a previous study where the plasma configuration was held fixed and the toroidal field was reversed [2]. In that study, differences in the divertor and X-point plasma were measured. In the present work, the X-point could not be located in the range of the divertor Thomson scattering diagnostic due to top/bottom symmetry issues, and those measurements are not available.

  4. Electric field strength in a silicon surface barrier detector with the presence of a dielectric plasma column

    International Nuclear Information System (INIS)

    Kanno, Ikuo

    1994-01-01

    The dynamic change of the electric field strength in a silicon surface barrier detector (SSBD) is studied. With the presence of a dielectric plasma column in the depletion layer of the SSBD, the electric field strength inside/outside the plasma column is suppressed/enhanced. As the length and the dielectric constant of the plasma column become shorter and smaller, the suppression and enhancement of the electric field strength become less. The electric field strength recovers the initial state, when the plasma column disappears. When the electrons and holes are inside/outside the dielectric plasma column, they have less/more electric potential than the one they have when there is no plasma column. During the movement of the electron/hole outside the plasma column to the positive/negative electrode, the enhanced electric field strength becomes smaller. Electron and hole pairs, which are the parts of the dielectric plasma column, arrive at positive and negative electrodes, having insufficient electric potential to induce the unit charge. This paper shows that the presence of a dielectric plasma column explains the main part of the residual defect in a SSBD. ((orig.))

  5. Electron density in surface barrier discharge emerging at argon/water interface: quantification for streamers and leaders

    Science.gov (United States)

    Cvetanović, Nikola; Galmiz, Oleksandr; Synek, Petr; Zemánek, Miroslav; Brablec, Antonín; Hoder, Tomáš

    2018-02-01

    Optical emission spectroscopy, fast intensified CCD imaging and electrical measurements were applied to investigate the basic plasma parameters of surface barrier discharge emerging from a conductive water electrode. The discharge was generated at the triple-line interface of atmospheric pressure argon gas and conductive water solution at the fused silica dielectrics using a sinusoidal high-voltage waveform. The spectroscopic methods of atomic line broadening and molecular spectroscopy were used to determine the electron densities and the gas temperature in the active plasma. These parameters were obtained for both applied voltage polarities and resolved spatially. Two different spectral signatures were identified in the spatially resolved spectra resulting in electron densities differing by two orders of magnitude. It is shown that two discharge mechanisms take a place: the streamer and the leader one, with electron densities of 1014 and 1016 cm-3, respectively. This spectroscopic evidence is supported by the combined diagnostics of electrical current measurements and phase-resolved intensified CCD camera imaging.

  6. Development of neutron detector using sensor type surface barrier with (n,p) and (n,α) converters

    International Nuclear Information System (INIS)

    Madi Filho, Tufic

    1999-01-01

    A Si semiconductor detector, surface barrier type, with a slim film of a converter material capable to produce charged particles was used as a sensor of neutrons in an environment of a zero power reactor. Two types of converters were used to improve the detection efficiency: (1) the polyethylene, n(CH 2 ), which produces recoil protons from the (n,p) interaction and, (2) the 10 B which generates a particle from the (n,alpha) reaction. The optimal thickness of those converters was determined experimentally and specifically for the polyethylene a mathematical model R(ips) = ε p · N 0 ·(1-e -Σ·Χ ) ·e -μ ·Χ + ε n · N 0 · -Σ · Χ was used to fit to the experimental data. For the polyethylene converter the thickness was of 0.058 cm (62.64 mg.cm -2 ) while for the 10 B it was equal to 6.55 [μm (1.54 mg.cm -2 ). The converter of polyethylene or 10 B improved the detection efficiency to a factor of 4.7 and 3.0 respectively. The comparison of the spectrum of the background radiation with the spectra of the recoil protons and the a radiation from the 10 B it was concluded that the polyethylene presented better performance than the 10 B converter. (author)

  7. Modification of the Absorption Edge of GaAs Arising from Hot-Electron Effects

    DEFF Research Database (Denmark)

    McGroddy, J. C.; Christensen, Ove

    1973-01-01

    We have observed a large enhancement of the electric-field-induced optical absorption arising from hot-electron effects in n-type GaAs at 77 K. The magnitude and field dependence of the enhancement can be approximately accounted for by a theory attributing the effect to broadening of the final...... states of the optical transitions by interaction with the nonequilibrium optical phonons produced by the hot electrons....

  8. ``Trickle Meter Gravimetry'': Precision Interferometry from Residual Berry Phase Edge Effects Involving Atoms Exiting an Accelerating Optical Lattice

    Science.gov (United States)

    Chubb, Scott

    2007-03-01

    From a generalization of conventional band theory, derived from a many-body form of multiple scattering theory, I rigorously showed that the semi-classical theory of cold atom transport in optical lattices could be related to changes in the zero of momentum of the ground state. The new formulation includes finite size effects. When the effects of excitation, associated with the loss of atoms at the boundaries of the lattice are included, in the adiabatic limit, in which the perturbing potential acts sufficiently slowly and weakly, topological changes in phase (which are equivalent to Berry phase effects in the conventional semi-classical theory) take place that introduce discontinuous changes in wave function phase (and flux). In a situation involving an accelerating optical lattice, containing ultra cold atoms in a Bose Einstein Condensate, these changes in wave function phase can be monitored and used to systematically alter the acceleration of the lattice (by altering the chirp frequency of one of one of the counter-propogating lasers), in such a way that a form of edge-effect interferometry can be performed, which, in principle, can be used to make precision measurements of gravity, with unprecedented accuracy. S.R.Chubb, Proc Roy Soc A, submitted (2006).

  9. Extremal surface barriers

    International Nuclear Information System (INIS)

    Engelhardt, Netta; Wall, Aron C.

    2014-01-01

    We present a generic condition for Lorentzian manifolds to have a barrier that limits the reach of boundary-anchored extremal surfaces of arbitrary dimension. We show that any surface with nonpositive extrinsic curvature is a barrier, in the sense that extremal surfaces cannot be continuously deformed past it. Furthermore, the outermost barrier surface has nonnegative extrinsic curvature. Under certain conditions, we show that the existence of trapped surfaces implies a barrier, and conversely. In the context of AdS/CFT, these barriers imply that it is impossible to reconstruct the entire bulk using extremal surfaces. We comment on the implications for the firewall controversy

  10. The Double-Edged Sword Effects of Mechanisms Disconnecting Cash-Flow Rights From Voting Rights

    DEFF Research Database (Denmark)

    Fattoum, Asma; Guedri, Zied

    On the one hand, defensive mechanisms such as dual class shares, pyramid structures and pact agreements may produce positive effects on firm performance because they enable CEOs to make long-term and risky investments without being worried by short-term market forces and risk-averse shareholders....

  11. Effects of V-shaped edge defect and H-saturation on spin-dependent electronic transport of zigzag MoS2 nanoribbons

    International Nuclear Information System (INIS)

    Li, Xin-Mei; Long, Meng-Qiu; Cui, Li-Ling; Xiao, Jin; Zhang, Xiao-Jiao; Zhang, Dan; Xu, Hui

    2014-01-01

    Based on nonequilibrium Green's function in combination with density functional theory calculations, the spin-dependent electronic transport properties of one-dimensional zigzag molybdenum disulfide (MoS 2 ) nanoribbons with V-shaped defect and H-saturation on the edges have been studied. Our results show that the spin-polarized transport properties can be found in all the considered zigzag MoS 2 nanoribbons systems. The edge defects, especially the V-shaped defect on the Mo edge, and H-saturation on the edges can suppress the electronic transport of the systems. Also, the spin-filtering and negative differential resistance behaviors can be observed obviously. The mechanisms are proposed for these phenomena. - Highlights: • The spin-dependent electronic transport of zigzag MoS 2 nanoribbons. • The effects of V-shaped edge defect and H-saturation. • The effects of spin-filter and negative differential resistance can be observed

  12. Influence of the core-hole effect on optical properties of magnesium oxide (MgO) near the Mg L-edge region.

    Science.gov (United States)

    Sinha, Mangalika; Modi, Mohammed H; Ghosh, Haranath; Yadav, P K; Gupta, R K

    2018-05-01

    The influence of the core-hole effect on optical properties of magnesium oxide (MgO) is established through experimental determination of optical constants and first-principles density functional theory studies. Optical constants (δ and β) of MgO thin film are measured in the spectral region 40-300 eV using reflectance spectroscopy techniques at the Indus-1 synchrotron radiation source. The obtained optical constants show strong core exciton features near the Mg L-edge region, causing significant mismatch with Henke's tabulated values. On comparing the experimentally obtained optical constants with Henke's tabulated values, an edge shift of ∼3.0 eV is also observed. Distinct evidence of effects of core exciton on optical constants (δ and β) in the near Mg L-edge absorption spectra are confirmed through first-principles simulations.

  13. Low speed wind tunnel test of ground proximity and deck edge effects on a lift cruise fan V/STOL configuration, volume 1

    Science.gov (United States)

    Stewart, V. R.

    1979-01-01

    The characteristics were determined of a lift cruise fan V/STOL multi-mission configuration in the near proximity to the edge of a small flat surface representation of a ship deck. Tests were conducted at both static and forward speed test conditions. The model (0.12 scale) tested was a four fan configuration with modifications to represent a three fan configuration. Analysis of data showed that the deck edge effects were in general less critical in terms of differences from free air than a full deck (in ground effect) configuration. The one exception to this was when the aft edge of the deck was located under the center of gravity. This condition, representative of an approach from the rear, showed a significant lift loss. Induced moments were generally small compared to the single axis control power requirements, but will likely add to the pilot work load.

  14. Effect of annealing ambient on anisotropic retraction of film edges during solid-state dewetting of thin single crystal films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gye Hyun; Thompson, Carl V., E-mail: cthomp@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239 (United States); Ma, Wen [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239 (United States); Yildiz, Bilge [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239 (United States); Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239 (United States)

    2016-08-21

    During solid-state dewetting of thin single crystal films, film edges retract at a rate that is strongly dependent on their crystallographic orientations. Edges with kinetically stable in-plane orientations remain straight as they retract, while those with other in-plane orientations develop in-plane facets as they retract. Kinetically stable edges have retraction rates that are lower than edges with other orientations and thus determine the shape of the natural holes that form during solid-state dewetting. In this paper, measurements of the retraction rates of kinetically stable edges for single crystal (110) and (100) Ni films on MgO are presented. Relative retraction rates of kinetically stable edges with different crystallographic orientations are observed to change under different annealing conditions, and this accordingly changes the initial shapes of growing holes. The surfaces of (110) and (100) films were also characterized using low energy electron diffraction, and different surface reconstructions were observed under different ambient conditions. The observed surface structures were found to correlate with the observed changes in the relative retraction rates of the kinetically stable edges.

  15. Autophagy and its effects: making sense of double-edged swords.

    Science.gov (United States)

    Thorburn, Andrew

    2014-10-01

    Autophagy is the mechanism by which cellular material is delivered to lysosomes and degraded. This process has become a major focus of biological and biomedical research with thousands of papers published each year and rapidly growing appreciation that autophagy affects many normal and pathological processes. However, as we learn more about this evolutionarily ancient process, we are discovering that autophagy's effects may work for both the good and the bad of an organism. Here, I discuss some of these context-dependent findings and how, as we make sense of them, we can try to apply our knowledge for practical purposes.

  16. Autophagy and its effects: making sense of double-edged swords.

    Directory of Open Access Journals (Sweden)

    Andrew Thorburn

    2014-10-01

    Full Text Available Autophagy is the mechanism by which cellular material is delivered to lysosomes and degraded. This process has become a major focus of biological and biomedical research with thousands of papers published each year and rapidly growing appreciation that autophagy affects many normal and pathological processes. However, as we learn more about this evolutionarily ancient process, we are discovering that autophagy's effects may work for both the good and the bad of an organism. Here, I discuss some of these context-dependent findings and how, as we make sense of them, we can try to apply our knowledge for practical purposes.

  17. [Alcohol intake--a two-edged sword. Part 1: metabolism and pathogenic effects of alcohol].

    Science.gov (United States)

    Ströhle, Alexander; Wolters, Maike; Hahn, Andreas

    2012-08-01

    From the biomedical point of view alcohol is a Janus-faced dietary component with a dose-dependent effect varying from cardiovascular protection to cytotoxicity. Alcohol is absorbed in the upper gastrointestinal tract by passive diffusion, is quickly distributed throughout body water and is mostly eliminated through oxidation. The enzymatically-catalyzed oxidative degradation to acetaldehyde and further to acetate is primarily localized in the liver. In case of a low blood alcohol concentration (0.5 per thousand) are increasingly oxidized by the microsomal ethanoloxidizing system (MEOS). Alcohol consumption induces several metabolic reactions as well as acute effects on the central nervous system. Chronic alcohol consumption to some extent irreparably damages nearly every organ with the liver being particularly concerned. There are three stages of alcohol-induced liver disease (fatty liver, alcohol hepatitis, liver cirrhosis) and the liver damages mainly result from reaction products of alcohol degradation (acetaldehyde, NADH and reactive oxygen species). An especially dreaded clinical complication of the alcohol-induced liver disease is the hepatic encephalopathy. Its pathogenesis is a multifactorial and self-perpetuating process with the swelling of astrocytes being a crucial point. Swollen astrocytes induce several reactions such as oxidative/nitrosative stress, impaired signal transduction, protein modifications and a modified gene expression profile. The swelling of astrocytes and the change in neuronal activity are attributed to several neurotoxins, especially ammonia and aromatic amino acids. In alcohol addicted subjects multiple micronutrient deficiencies are common. The status of folic acid, thiamine, pyridoxine and zinc is especially critical.

  18. Assessing Anthropogenic Influence and Edge Effect Influence on Forested Riparian Buffer Spatial Configuration and Structure: An Example Using Lidar Remote Sensing Methods

    Science.gov (United States)

    Wasser, L. A.; Chasmer, L. E.

    2012-12-01

    Forested riparian buffers (FRB) perform numerous critical ecosystem services. However, globally, FRB spatial configuration and structure have been modified by anthropogenic development resulting in widespread ecological degradation as seen in the Gulf of Mexico and the Chesapeake Bay. Riparian corridors within developed areas are particularly vulnerable to disturbance given two edges - the naturally occurring stream edge and the matrix edge. Increased edge length predisposes riparian vegetation to "edge effects", characterized by modified physical and environmental conditions at the interface between the forested buffer and the adjacent landuse, or matrix and forest fragment degradation. The magnitude and distance of edge influence may be further influenced by adjacent landuse type and the width of the buffer corridor at any given location. There is a need to quantify riparian buffer spatial configuration and structure over broad geographic extents and within multiple riparian systems in support of ecologically sound management and landuse decisions. This study thus assesses the influence of varying landuse types (agriculture, suburban development and undeveloped) on forested riparian buffer 3-dimensional structure and spatial configuration using high resolution Light Detection and Ranging (LiDAR) data collected within a headwater watershed. Few studies have assessed riparian buffer structure and width contiguously for an entire watershed, an integral component of watershed planning and restoration efforts such as those conducted throughout the Chesapeake Bay. The objectives of the study are to 1) quantify differences in vegetation structure at the stream and matrix influenced riparian buffer edges, compared to the forested interior and 2) assess continuous patterns of changes in vegetation structure throughout the buffer corridor beginning at the matrix edge and ending at the stream within buffers a) of varying width and b) that are adjacent to varying landuse

  19. Effect of the van der Waals interaction on the electron energy-loss near edge structure theoretical calculation

    Energy Technology Data Exchange (ETDEWEB)

    Katsukura, Hirotaka; Miyata, Tomohiro; Tomita, Kota; Mizoguchi, Teruyasu, E-mail: teru@iis.u-tokyo.ac.jp

    2017-07-15

    The effect of the van der Waals (vdW) interaction on the simulation of the electron energy-loss near edge structure (ELNES) by a first-principles band-structure calculation is reported. The effect of the vdW interaction is considered by the Tkatchenko-Scheffler scheme, and the change of the spectrum profile and the energy shift are discussed. We perform calculations on systems in the solid, liquid and gaseous states. The transition energy shifts to lower energy by approximately 0.1 eV in the condensed (solid and liquid) systems by introducing the vdW effect into the calculation, whereas the energy shift in the gaseous models is negligible owing to the long intermolecular distance. We reveal that the vdW interaction exhibits a larger effect on the excited state than the ground state owing to the presence of an excited electron in the unoccupied band. Moreover, the vdW effect is found to depend on the local electron density and the molecular coordination. In addition, this study suggests that the detection of the vdW interactions exhibited within materials is possible by a very stable and high resolution observation. - Highlights: • Effect of van der Waals (vdW) interaction in ELNES calculation is investigated. • The vdW interaction influences more to the excited state owing to the presence of excited electron. • The vdW interaction makes spectral shift to lower energy side by 0.1–0.01 eV. • The vdW interaction is negligible in gaseous materials due to long intermolecular distance.

  20. Refractive index of ternary and quaternary compound semiconductors below the fundamental absorption edge: Linear and nonlinear effects

    International Nuclear Information System (INIS)

    Jensen, B.; Torabi, A.

    1985-01-01

    The index of refraction n is calculated as a function of frequency and mole fraction x for the following compounds: Hg/sub l-x/Cd/sub x/Te, Al/sub x/Ga/sub l-x/As, and In/sub l-x/Ga/sub x/As/sub y/P/sub l-y/ lattice matched to InP. Lattice matching of In/sub l-x/Ga/sub x/As/sub y/P/sub l-y/ to InP requires that x = 0.466 y. The theoretical result for the refractive index is obtained from a quantum mechanical calculation of the dielectric constant of a compound semiconductor. It is given in terms of the basic material parameters of band gap energy, effective electron mass m/sub n/, effective heavy hole mass m/sub rho/, spin orbit splitting energy, lattice constant, and carrier concentration n/sub e/ or rho for n-type or rho-type materials, respectively. If these quantities are known as functions of mole fraction x, there are no adjustable parameters involved. A negative change in the refractive index near the fundamental absorption edge is predicted on passing radiation through a crystal if the change in carrier concentration of the initially unoccupied conduction band is assumed proportional to internal intensity I. Comparison of theory with experimental data is given

  1. The effect of dephasing on edge state transport through p-n junctions in HgTe/CdTe quantum wells.

    Science.gov (United States)

    Zhang, Ying-Tao; Song, Juntao; Sun, Qing-Feng

    2014-02-26

    Using the Landauer-Büttiker formula, we study the effect of dephasing on the transport properties of the HgTe/CdTe p-n junction. It is found that in the HgTe/CdTe p-n junction the topologically protected gapless helical edge states manifest a quantized 2e²/h plateau robust against dephasing, in sharp contrast to the case for the normal HgTe/CdTe quantum well. This robustness of the transport properties of the edge states against dephasing should be attributed to the special construction of the HgTe/CdTe p-n junction, which limits the gapless helical edge states to a very narrow region and thus weakens the influence of the dephasing on the gapless edge states to a large extent. Our results demonstrate that the p-n junction could be a substitute device for use in experimentally observing the robust edge states and quantized plateau. Finally, we present a feasible scheme based on current experimental methods.

  2. Effect of an edge at cup rim on contact stress during micro-separation in ceramic-on-ceramic hip joints.

    Science.gov (United States)

    Liu, Feng; Fisher, John

    2017-09-01

    Alumina ceramic total hip joint bearings have shown superior wear properties. The joint bearing may undergo adverse conditions such as micro-separation causing head contact on the cup rim. As a transition, an edge is formed between the cup bearing and the rim. The aim of this study was to predict the effect of the edge on contact stresses in order to better understand the mechanisms of wear. A finite element contact model was developed under the conditions of the head displacements 0.5-2 mm and vertical loads 0.5-3 kN. The edge contact produced the most severe stresses capable of causing elevated wear and damage to ceramic bearings. The study shows that the bearing design should be considered in association with clinical conditions to eliminate severe stress.

  3. Effects of the edge shape and the width on the structural and electronic properties of silicene nanoribbons

    International Nuclear Information System (INIS)

    Song Yuling; Zhang Yan; Zhang Jianmin; Lu Daobang

    2010-01-01

    Under the generalized gradient approximation (GGA), the structural and electronic properties are studied for H-terminated silicene nanoribbons (SiNRs) with either zigzag edge (ZSiNRs) or armchair edge (ASiNRs) by using the first-principles projector-augmented wave potential within the density function theory (DFT) framework. The results show that the length of the Si-H bond is always 1.50 A, but the edge Si-Si bonds are shorter than the inner ones with identical orientation, implying a contraction relaxation of edge Si atoms. An edge state appears at the Fermi level E F in broader ZSiNRs, but does not appear in all ASiNRs due to their dimer Si-Si bond at edge. With increasing width of ASiNRs, the direct band gaps exhibit not only an oscillation behavior, but also a periodic feature of Δ 3n > Δ 3n+1 > Δ 3n+2 for a certain integer n. The charge density contours analysis shows that the Si-H bond is an ionic bond due to a relative larger electronegativity of H atom. However, all kinds of the Si-Si bonds display a typical covalent bonding feature, although their strength depends on not only the bond orientation but also the bond position. That is, the larger deviation of the Si-Si bond orientation from the nanoribbon axis as well as the closer of the Si-Si bond to the nanoribbon edge, the stronger strength of the Si-Si bond. Besides the contraction of the nanoribbon is mainly in its width direction especially near edge, the addition contribution from the terminated H atoms may be the other reason.

  4. EMC3-Eirene simulations of gas puff effects on edge density and ICRF coupling in ASDEX Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei; Noterdaeme, Jean-Marie [Max Planck Institute for Plasma Physics, Garching (Germany); University of Ghent, Ghent (Belgium); Coster, David; Lunt, Tilmann; Bobkov, Volodymyr; Feng, Yuehe [Max Planck Institute for Plasma Physics, Garching (Germany); Collaboration: ASDEX Upgrade team

    2015-05-01

    Ion cyclotron range of frequency (ICRF) heating relies on the Fast Wave (FW) to transport the power from the edge (the antenna) to the plasma center. Since the FW is evanescent below a critical density (typically in the 10{sup 18} m{sup -3} range), the wave does not propagate in the region where the density is below this value in the very edge of the plasma. The coupling depends strongly on the width of this region. The distance between the ICRF antenna and the FW cut-off layer can be made smaller by increasing the edge density in front of the ICRF antenna. Previous experiments in many tokamaks and preliminary simulation results for AUG and JET with EDGE2D-EIRENE show that the edge density could indeed be increased with gas puffing at the top of the vessel or in the midplane. But the 2D code cannot quantitatively reproduce the experimental results, mainly due to the assumptions of toroidal axisymmetry. EMC3-EIRENE is a 3D Edge Monte Carlo plasma fluid transport code. By including the toroidal nonaxisymmetric plasma facing components and 3D positions of gas valves in the code, the simulations can be made more realistic. We will show first simulation results of the code and a comparison to experiments.

  5. X-ray Faraday effect at the L.sub.2,3./sub. edges of Fe, Co, and Ni: theory and experiment

    Czech Academy of Sciences Publication Activity Database

    Kuneš, Jan; Oppeneer, P. M.; Mertins, H. Ch.; Schäfers, F.; Gaupp, A.; Gudat, W.; Novák, Pavel

    2001-01-01

    Roč. 64, - (2001), s. 174417-1-174417-10 ISSN 0163-1829 Institutional research plan: CEZ:AV0Z1010914 Keywords : X-ray Faraday effect * L 2 * 3 edges * 3d ferromagnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.070, year: 2001

  6. Symmetry-Dependent Spin Transport Properties and Spin-Filter Effects in Zigzag-Edged Germanene Nanoribbons

    Directory of Open Access Journals (Sweden)

    Can Cao

    2015-01-01

    Full Text Available We performed the first-principles calculations to investigate the spin-dependent electronic transport properties of zigzag-edged germanium nanoribbons (ZGeNRs. We choose of ZGeNRs with odd and even widths of 5 and 6, and the symmetry-dependent transport properties have been found, although the σ mirror plane is absent in ZGeNRs. Furthermore, even-N and odd-N ZGeNRs have very different current-voltage relationships. We find that the even 6-ZGeNR shows a dual spin-filter effect in antiparallel (AP magnetism configuration, but the odd 5-ZGeNR behaves as conventional conductors with linear current-voltage dependence. It is found that when the two electrodes are in parallel configuration, the 6-ZGeNR system is in a low resistance state, while it can switch to a much higher resistance state when the electrodes are in AP configuration, and the magnetoresistance of 270% can be observed.

  7. Effect of neutrals localized at torus inboard side on the impurity transport in edge stochastic magnetic field layer of LHD

    International Nuclear Information System (INIS)

    Morita, S.; Oishi, T.; Kobayashi, M.; Goto, M.; Kawamura, G.; Zhang, H.M.; Hunag, X.L.; Wang, E.H.

    2014-01-01

    Two-dimensional (2-D) distribution of impurity line emissions has been measured in Large Helical Device (LHD) based on the 2-D extreme ultraviolet (EUV) spectroscopy for studying the edge impurity transport in stochastic magnetic field layer with three-dimensional (3-D) structure. The impurity behavior in the vicinity of two X-points at inboard and outboard sides of torus becomes separately visible with the 2-D measurement. As a result, it is found that the carbon location changes from inboard to outboard X-points when the plasma axis is shifted from R_a_x=3.6 m to 3.75 m. A 3-D simulation with EMC3-EIRENE code agrees with the result at R_a_x=3.75 m but disagreed with the result at R_a_x=3.60 m. The discrepancy between the measurement and simulation at R_a_x=3.60 m is considerably reduced when the effect of neutral hydrogen localized at the inboard side is taken into account, which can modify the density gradient and friction force along the magnetic field. (author)

  8. Effect of jet nozzle geometry on flow and heat transfer performance of vortex cooling for gas turbine blade leading edge

    International Nuclear Information System (INIS)

    Du, Changhe; Li, Liang; Wu, Xin; Feng, Zhenping

    2016-01-01

    Highlights: • We establish a suitable vortex chamber model for gas turbine blade leading edge. • Mechanism of vortex cooling is further discussed and presented. • Influences of jet nozzle geometry on vortex cooling characteristics are researched. • This paper focuses on assessment of flow field and thermal performance for different jet nozzle aspect ratio and area. - Abstract: In this paper, 3D viscous steady Reynolds Averaged Navier–Stokes (RANS) equations are utilized to investigate the influence of jet nozzle geometry on flow and thermal behavior of vortex cooling for gas turbine blades. Comparison between calculation with different turbulence models and the experimental data is conducted, and results show that the standard k-ω model provides the best accuracy. The grid independence analysis is performed to obtain the proper mesh number. First, the mechanism of vortex cooling is further discussed, and the pronounced impact of kinetic turbulence intensity, thin thermal boundary layer, violent radial convection and complex vortices on enhanced heat transfer performance is confirmed. Then, seven jet nozzle aspect ratios and seven jet nozzle to chamber cross section area ratios are selected to research the flow field and thermal characteristics of vortex cooling focusing on the streamline, static pressure ratio, total pressure loss ratio and Nusselt number. It is presented that the jet nozzle aspect ratio and jet nozzle to chamber cross section area ratio both impose a significant effect on the flow and thermal parameters. The averaged Nusselt number decreases at first and then increases with the increasing jet nozzle aspect ratio, reaching highest when aspect ratio equals to 1. The effect of area ratio on averaged Nusselt number is complex. Finally, the heat transfer results in this study are compared with other previous works. Results indicate that good agreement with previous data is achieved, and the enhanced thermal behavior may be acquired by

  9. Effect of ion orbit loss on the structure in the H-mode tokamak edge pedestal profiles of rotation velocity, radial electric field, density, and temperature

    International Nuclear Information System (INIS)

    Stacey, Weston M.

    2013-01-01

    An investigation of the effect of ion orbit loss of thermal ions and the compensating return ion current directly on the radial ion flux flowing in the plasma, and thereby indirectly on the toroidal and poloidal rotation velocity profiles, the radial electric field, density, and temperature profiles, and the interpretation of diffusive and non-diffusive transport coefficients in the plasma edge, is described. Illustrative calculations for a high-confinement H-mode DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] plasma are presented and compared with experimental results. Taking into account, ion orbit loss of thermal ions and the compensating return ion current is found to have a significant effect on the structure of the radial profiles of these quantities in the edge plasma, indicating the necessity of taking ion orbit loss effects into account in interpreting or predicting these quantities

  10. Nanoindentation near the edge

    Science.gov (United States)

    J.E. Jakes; C.R. Frihart; J.F. Beecher; R.J. Moon; P.J. Resto; Z.H. Melgarejo; O.M. Saurez; H. Baumgart; A.A. Elmustafa; D.S. Stone

    2009-01-01

    Whenever a nanoindent is placed near an edge, such as the free edge of the specimen or heterophase interface intersecting the surface, the elastic discontinuity associated with the edge produces artifacts in the load-depth data. Unless properly handled in the data analysis, the artifacts can produce spurious results that obscure any real trends in properties as...

  11. Edge of polar cap patches

    Science.gov (United States)

    Hosokawa, K.; Taguchi, S.; Ogawa, Y.

    2016-04-01

    On the night of 4 December 2013, a sequence of polar cap patches was captured by an all-sky airglow imager (ASI) in Longyearbyen, Norway (78.1°N, 15.5°E). The 630.0 nm airglow images from the ASI of 4 second exposure time, oversampled the emission of natural lifetime (with quenching) of at least ˜30 sec, introduce no observational blurring effects. By using such high-quality ASI images, we succeeded in visualizing an asymmetry in the gradients between the leading/trailing edges of the patches in a 2-D fashion. The gradient in the leading edge was found to be 2-3 times steeper than that in the trailing edge. We also identified fingerlike structures, appearing only along the trailing edge of the patches, whose horizontal scale size ranged from 55 to 210 km. These fingers are considered to be manifestations of plasma structuring through the gradient-drift instability (GDI), which is known to occur only along the trailing edge of patches. That is, the current 2-D observations visualized, for the first time, how GDI stirs the patch plasma and such a mixing process makes the trailing edge more gradual. This result strongly implies a close connection between the GDI-driven plasma stirring and the asymmetry in the large-scale shape of patches and then suggests that the fingerlike structures can be used as markers to estimate the fine-scale structure in the plasma flow within patches.

  12. Measurements of the edge current evolution and comparison with neoclassical calculations during MAST H-modes using motional Stark effect

    NARCIS (Netherlands)

    de Bock, M. F. M.; Citrin, J.; Saarelma, S.; Temple, D.; Conway, N. J.; Kirk, A.; Meyer, H.; Michael, C. A.

    2012-01-01

    Edge localized modes (ELMs), that are present in most tokamak H-(high confinement) modes, can cause significant damage to plasma facing components in fusion reactors. Controlling ELMs is considered necessary and hence it is vital to understand the underlying physics. The stability of ELMs is

  13. Measurements of the edge current evolution and comparison with neoclassical calculations during MAST H-modes using motional Stark effect

    NARCIS (Netherlands)

    Bock, de M.F.M.; Citrin, J.; Saarelma, S.; Temple, D.; Conway, N.J.; Kirk, A.; Meyer, H.; Michael, C.A.

    2012-01-01

    Edge localized modes (ELMs), that are present in most tokamak H- (high confinement) modes, can cause significant damage to plasma facing components in fusion reactors. Controlling ELMs is considered necessary and hence it is vital to understand the underlying physics. The stability of ELMs is

  14. Effect of edge plasmons on the optical properties of MoS2 monolayer flakes

    DEFF Research Database (Denmark)

    Rossi, Tuomas P.; Winther, Kirsten Trøstrup; Jacobsen, Karsten Wedel

    2017-01-01

    . Thus, we observe that while an evenly-spaced edge configuration supports one-dimensional (1D) plasmon modes similar to those of an ideal 1D electron gas, the relaxed structures show mixed plasmon and single-electron excitations in the low-energy response. Our findings illustrate the sensitivity...

  15. Trans-Boundary Edge Effects in the Western Carpathians: The Influence of Hunting on Large Carnivore Occupancy

    Science.gov (United States)

    Váňa, Martin; Suchomel, Josef; Chapron, Guillaume; López-Bao, José Vicente

    2016-01-01

    The conservation and management of wolves Canis lupus in the periphery of their distribution is challenging. Edges of wolf distribution are characterized by very few and intermittent occurrences of individuals, which are modulated by multiple factors affecting the overall population such as human-caused mortality, management targets and food availability. The knowledge of population dynamics in the edges becomes crucial when hunting takes place nearby the edges, which may preclude population expansion. Here, using as example the occurrence of wolves in the Beskydy Mountains (Czech-Slovak border), which are the edge distribution of the wolf and Eurasian lynx Lynx lynx populations in the West Carpathians, we explored how food availability and hunting in the Slovakian core area affected the dynamics of wolves in the edges of this population. During 2003–2012, we monitored large carnivore occurrence by snow-tracking surveys and tested potential differences in the occurrence of these species in Beskydy Mountains and potential mechanisms behind detected patterns. Despite the proximity to the core area, with several wolf reproductions being confirmed at least in recent years, the wolf was a very rare species in Beskydy and was recorded 14 times less often than the lynx. The expected abundance of wolves in the Beskydy Mountains was inversely related to prey availability in the Slovakian core area. Wolf hunting the year before influenced the expected abundance of wolves in Beskydy area. We discuss how different life histories and legal status of both species probably account for most of the observed difference of occurrence at range margins. PMID:28002475

  16. Trans-Boundary Edge Effects in the Western Carpathians: The Influence of Hunting on Large Carnivore Occupancy.

    Science.gov (United States)

    Kutal, Miroslav; Váňa, Martin; Suchomel, Josef; Chapron, Guillaume; López-Bao, José Vicente

    2016-01-01

    The conservation and management of wolves Canis lupus in the periphery of their distribution is challenging. Edges of wolf distribution are characterized by very few and intermittent occurrences of individuals, which are modulated by multiple factors affecting the overall population such as human-caused mortality, management targets and food availability. The knowledge of population dynamics in the edges becomes crucial when hunting takes place nearby the edges, which may preclude population expansion. Here, using as example the occurrence of wolves in the Beskydy Mountains (Czech-Slovak border), which are the edge distribution of the wolf and Eurasian lynx Lynx lynx populations in the West Carpathians, we explored how food availability and hunting in the Slovakian core area affected the dynamics of wolves in the edges of this population. During 2003-2012, we monitored large carnivore occurrence by snow-tracking surveys and tested potential differences in the occurrence of these species in Beskydy Mountains and potential mechanisms behind detected patterns. Despite the proximity to the core area, with several wolf reproductions being confirmed at least in recent years, the wolf was a very rare species in Beskydy and was recorded 14 times less often than the lynx. The expected abundance of wolves in the Beskydy Mountains was inversely related to prey availability in the Slovakian core area. Wolf hunting the year before influenced the expected abundance of wolves in Beskydy area. We discuss how different life histories and legal status of both species probably account for most of the observed difference of occurrence at range margins.

  17. Soil, plant, and structural considerations for surface barriers in arid environments: Application of results from studies in the Mojave Desert near Beatty, Nevada

    Science.gov (United States)

    Andraski, Brian J.; Prudic, David E.; ,

    1997-01-01

    The suitability of a waste-burial site depends on hydrologic processes that can affect the near-surface water balance. In addition, the loss of burial trench integrity by erosion and subsidence of trench covers may increase the likelihood of infiltration and percolation, thereby reducing the effectiveness of the site in isolating waste. Although the main components of the water balance may be defined, direct measurements can be difficult, and actual data for specific locations are seldom available. A prevalent assumption is that little or no precipitation will percolate to buried wastes at an arid site. Thick unsaturated zones, which are common to arid regions, are thought to slow water movement and minimize the risk of waste migration to the underlying water table. Thus, reliance is commonly placed on the natural system to isolate contaminants at waste-burial sites in the arid West.Few data are available to test assumptions about the natural soil-water flow systems at arid sites, and even less is known about how the natural processes are altered by construction of a waste-burial facility. The lack of data is the result of technical complexity of hydraulic characterization of the dry, stony soils, and insufficient field studies that account for the extreme temporal and spatial variations in precipitation, soils, and plants in arid regions. In 1976, the U.S. Geological Survey (USGS) began a long-term study at a waste site in the Mojave Desert. This paper summarizes the findings of ongoing investigations done under natural-site and waste-burial conditions, and discusses how this information may be applied to the design of surface barriers for waste sites in arid environments.The waste-burial site is in one of the most arid parts of the United States and is about 40 km northeast of Death Valley, near Beatty, Nev. (Figure 1). Precipitation averaged 108 mm/yr during 1981-1992. The water table is 85-115 m below land surface (Fischer, 1992). Sediments are largely alluvial

  18. Experimental investigation of the effects of blowing conditions and Mach number on the unsteady behavior of coolant ejection through a trailing edge cutback

    International Nuclear Information System (INIS)

    Barigozzi, Giovanna; Armellini, Alessandro; Mucignat, Claudio; Casarsa, Luca

    2012-01-01

    Highlights: ► Flow visualization and PIV documented the presence of large coherent structures. ► The presence of coherent structures is documented up to the vane trailing edge. ► Shape and direction of rotation of vortices change with injection conditions. ► Vortices morphology influences the film cooling effectiveness distributions. ► A Mach number increase moves vortices closer to the wall. - Abstract: The present paper shows the results of an experimental investigation into the unsteadiness of coolant ejection at the trailing edge of a highly loaded nozzle vane cascade. The trailing edge cooling scheme features a pressure side cutback with film cooling slots, stiffened by evenly spaced ribs in an inline configuration. Cooling air is also ejected through two rows of cylindrical holes placed upstream of the cutback. Tests were performed with a low inlet turbulence intensity level (Tu 1 = 1.6%), changing the cascade operating conditions from low speed (M 2is = 0.2) up to high subsonic regime (M 2is = 0.6), and with coolant to main stream mass flow ratio varied within the 0.5–2.0% range. Particle Image Velocimetry (PIV) and flow visualizations were used to investigate the unsteady mixing process taking place between coolant and main flow downstream of the cutback, up to the trailing edge. For all the tested conditions, the results show the presence of large coherent structures, which presence is still evident up to the trailing edge. Their shape and direction of rotation change with injection conditions, as a function of coolant to mainstream velocity ratio, strongly influencing the thermal protection capability of the injected coolant flow. The Mach number increase is only responsible for a positioning of such vortical structures closer to the wall, while the Strouhal number almost remains unchanged.

  19. The double-edged effects of annealing MgO underlayers on the efficient synthesis of single-wall carbon nanotube forests.

    Science.gov (United States)

    Tsuji, Takashi; Hata, Kenji; Futaba, Don N; Sakurai, Shunsuke

    2017-11-16

    Recently, the millimetre-scale, highly efficient synthesis of single-wall carbon nanotube (SWCNT) forests from Fe catalysts has been reported through the annealing of the magnesia (MgO) underlayer. Here, we report the double-edged effects of underlayer annealing on the efficiency and structure of the SWCNT forest synthesis through a temperature-dependent examination. Our results showed that the efficiency of the SWCNT forests sharply increased with increased underlayer annealing temperatures from 600 °C up to 900 °C due to a temperature-dependent structural modification, characterized by increased grain size and reduced defects, of the MgO underlayer. Beyond this temperature, the SWCNT fraction also decreased as a result of further structural modification of the MgO underlayer. This exemplifies the double-edged effects of annealing. Specifically, for underlayer annealing below 600 °C, the catalyst subsurface diffusion was found to limit the growth efficiency, and for excessively high underlayer annealing temperatures (>900 °C), catalyst coalescence/ripening led to the formation of double-wall carbon nanotubes. As a result, three distinct regions of synthesis were observed: (i) a "low yield" region below a threshold temperature (∼600 °C); (ii) an "increased yield" region from 600 to 900 °C, and (iii) a "saturation" region above 900 °C. The efficient SWCNT forest synthesis could only occur within a specific annealing temperature window as a result of this double-edged effects of underlayer annealing.

  20. Does the edge effect influence plant community structure in a tropical dry forest? O efeito de borda influencia a estrutura da comunidade vegetal em uma floresta tropical seca?

    Directory of Open Access Journals (Sweden)

    Diogo Gallo Oliveira

    2013-04-01

    Full Text Available Edge effects are considered a key factor in regulating the structure of plant communities in different ecosystems. However, regardless to few studies, edge influence does not seem to be decisive in semiarid regions such as the Brazilian tropical dry forest known as Caatinga but this issue remains inconclusive. The present study tests the null hypothesis that the plant community of shrubs and trees does not change in its structure due to edge effects. Twenty-four plots (20 x 20 m were set up in a fragment of Caatinga, in which 12 plots were in the forest edges and 12 plots were inside the fragment. Tree richness, abundance and species composition did not differ between edge and interior plots. The results of this study are in agreement with the pattern previously found for semiarid environments and contrasts with previous results obtained in different environments such as Rainforests, Savanna and Forest of Araucaria, which indicate abrupt differences between the border and interior of the plant communities in these ecosystems, and suggest that the community of woody plants of the Caatinga is not ecologically affected by the presence of edges.Efeitos de borda são considerados fator-chave na regulação da estrutura de comunidades vegetais em diferentes ecossistemas. Entretanto, apesar dos poucos estudos relacionados, o efeito de borda parece não ser determinante em regiões semiáridas, como a floresta tropical seca brasileira, conhecida como Caatinga. Este estudo testou a hipótese nula de que a comunidade vegetal arbustivo-arbórea não sofre alterações em sua estrutura, riqueza e composição devido ao efeito de borda. Foram instaladas 24 parcelas (20 x 20 m em um fragmento de Caatinga arbórea, sendo 12 parcelas na borda do fragmento e 12 parcelas no seu interior. A riqueza, abundância e composição das espécies não diferiram estatisticamente entre as parcelas de borda e interior. Os resultados deste estudo corroboram um possível padr

  1. Edge-rich MoS_2 Naonosheets Rooting into Polyaniline Nanofibers as Effective Catalyst for Electrochemical Hydrogen Evolution

    International Nuclear Information System (INIS)

    Zhang, Nan; Ma, Weiguang; Wu, Tongshun; Wang, Haoyu; Han, Dongxue; Niu, Li

    2015-01-01

    Graphical abstract: For the first time polyaniline (PANI) was employed as an admirable substrate to construct the hierarchical integrative hybrid with MoS_2 (MoS_2/PANI) for hydrogen evolution reaction (HER), which achieved great active edges exposure and excellent HER performance. - Highlights: • PANI is first applied as the support of MoS_2 for enhanced HER performance. • Great active edges exposure of the hybrid significantly benefits the HER activity. • Superior HER activity and excellent stability of MoS_2/PANI have been achieved. - Abstract: Conductive polymer polyaniline (PANI) with abundant protonated sites which are beneficial to hydrogen evolution reaction (HER), was applied as the support of MoS_2 for enhanced HER performance for the first time. The novel three dimensional (3D) HER catalyst (MoS_2/PANI) was constructed with two dimensional (2D) MoS_2 building blocks rooting into the integrative nanowires. PANI nanofibers acted as excellent substrates for the uniform, dense and approximate vertical growth of MoS_2 nanosheets exposing abundant active edges. Consequently, excellent HER performance has been achieved with a low onset overpotential of 100 mV and a small Tafel slope of 45 mV dec"−"1. Most importantly, it only needed 200 and 247 mV overpotential to reach the current density of 30 and 100 mA/cm"2 respectively. Additionally, MoS_2/PANI has achieved superior stability over other MoS_2-polymer-based HER electrocatalyst. In general, for the first time, employing PANI for the construction of the edge-rich integrative hybrid has successfully achieved an outstanding HER performance.

  2. Magnetic configuration effects on the edge heat flux in the limiter plasma on W7-X measured using the infrared camera and the combined probe

    Science.gov (United States)

    P, DREWS; H, NIEMANN; J, COSFELD; Y, GAO; J, GEIGER; O, GRULKE; M, HENKEL; D, HÖSCHEN; K, HOLLFELD; C, KILLER; A, KRÄMER-FLECKEN; Y, LIANG; S, LIU; D, NICOLAI; O, NEUBAUER; M, RACK; B, SCHWEER; G, SATHEESWARAN; L, RUDISCHHAUSER; N, SANDRI; N, WANG; the W7-X Team

    2018-05-01

    Controlling the heat and particle fluxes in the plasma edge and on the plasma facing components is important for the safe and effective operation of every magnetically confined fusion device. This was attempted on Wendelstein 7-X in the first operational campaign, with the modification of the magnetic configuration by use of the trim coils and tuning the field coil currents, commonly named iota scan. Ideally, the heat loads on the five limiters are equal. However, they differ between each limiter and are non-uniform, due to the (relatively small) error fields caused by the misalignment of components. It is therefore necessary to study the influence of the configuration changes on the transport of heat and particles in the plasma edge caused by the application of error fields and the change of the magnetic configuration. In this paper the up-stream measurements conducted with the combined probe are compared to the downstream measurements with the DIAS infrared camera on the limiter.

  3. Effect of atomic vibrations in XANES: polarization-dependent damping of the fine structure at the Cu K-edge of (creat)2CuCl4.

    Science.gov (United States)

    Šipr, Ondřej; Vackář, Jiří; Kuzmin, Alexei

    2016-11-01

    Polarization-dependent damping of the fine structure in the Cu K-edge spectrum of creatinium tetrachlorocuprate [(creat) 2 CuCl 4 ] in the X-ray absorption near-edge structure (XANES) region is shown to be due to atomic vibrations. These vibrations can be separated into two groups, depending on whether the respective atoms belong to the same molecular block; individual molecular blocks can be treated as semi-rigid entities while the mutual positions of these blocks are subject to large mean relative displacements. The effect of vibrations can be efficiently included in XANES calculations by using the same formula as for static systems but with a modified free-electron propagator which accounts for fluctuations in interatomic distances.

  4. Functional and Biomechanical Effects of the Edge-to-Edge Repair in the Setting of Mitral Regurgitation: Consolidated Knowledge and Novel Tools to Gain Insight into Its Percutaneous Implementation.

    Science.gov (United States)

    Sturla, Francesco; Redaelli, Alberto; Puppini, Giovanni; Onorati, Francesco; Faggian, Giuseppe; Votta, Emiliano

    2015-06-01

    Mitral regurgitation is the most prevalent heart valve disease in the western population. When severe, it requires surgical treatment, repair being the preferred option. The edge-to-edge repair technique treats mitral regurgitation by suturing the leaflets together and creating a double-orifice valve. Due to its relative simplicity and versatility, it has become progressively more widespread. Recently, its percutaneous version has become feasible, and has raised interest thanks to the positive results of the Mitraclip(®) device. Edge-to-edge features and evolution have stimulated debate and multidisciplinary research by both clinicians and engineers. After providing an overview of representative studies in the field, here we propose a novel computational approach to the most recent percutaneous evolution of the edge-to-edge technique. Image-based structural finite element models of three mitral valves affected by posterior prolapse were derived from cine-cardiac magnetic resonance imaging. The models accounted for the patient-specific 3D geometry of the valve, including leaflet compound curvature pattern, patient-specific motion of annulus and papillary muscles, and hyperelastic and anisotropic mechanical properties of tissues. The biomechanics of the three valves throughout the entire cardiac cycle was simulated before and after Mitraclip(®) implantation, assessing the biomechanical impact of the procedure. For all three simulated MVs, Mitraclip(®) implantation significantly improved systolic leaflets coaptation, without inducing major alterations in systolic peak stresses. Diastolic orifice area was decreased, by up to 58.9%, and leaflets diastolic stresses became comparable, although lower, to systolic ones. Despite established knowledge on the edge-to-edge surgical repair, latest technological advances make its percutanoues implementation a challenging field of research. The modeling approach herein proposed may be expanded to analyze clinical scenarios that

  5. Theoretical insights into the effect of terrace width and step edge coverage on CO adsorption and dissociation over stepped Ni surfaces.

    Science.gov (United States)

    Yang, Kuiwei; Zhang, Minhua; Yu, Yingzhe

    2017-07-21

    Vicinal surfaces of Ni are model catalysts of general interest and great importance in computational catalysis. Here we report a comprehensive study conducted with density functional theory on Ni[n(111) × (100)] (n = 2, 3 and 4) surfaces to explore the effect of terrace width and step edge coverage on CO adsorption and dissociation, a probe reaction relevant to many industrial processes. The coordination numbers (CN), the generalized coordination numbers and the d band partial density of states (d-PDOS) of Ni are identified as descriptors to faithfully reflect the difference of the step edge region for Ni[n(111) × (100)]. Based on analysis of the energy diagrams for CO activation and dissociation as well as the structural features of the Ni(311), Ni(211) and Ni(533) surfaces, Ni(211) (n = 3) is proposed as a model of adequate representativeness for Ni[n(111) × (100)] (n≥ 3) surface groups in investigating small molecule activation over such stepped structures. Further, a series of Ni(211) surfaces with the step edge coverage ranging from 1/4 to 1 monolayer (ML) were utilized to assess their effect on CO activation. The results show that CO adsorption is not sensitive to the step edge coverage, which could readily approach 1 ML under a CO-rich atmosphere. In contrast, CO dissociation manifests strong coverage dependence when the coverage exceeds 1/2 ML, indicating that significant adsorbate-adsorbate interactions emerge. These results are conducive to theoretical studies of metal-catalyzed surface processes where the defects play a vital role.

  6. [Effect of medicines for activating blood and reinforcing Qi on angiogenesis in infarcted myocardium edge area of acute myocardial infarction model in rats].

    Science.gov (United States)

    Zang, Wen-Hua; Yin, Shen-Hua; Tang, De-Cai; Li, Bing-Bing

    2014-03-01

    To study the effect of medicines for activating blood and reinforcing Qi on the number of new micro-vessels and the protein expressions of VEGF and bFGF in the infarcted myocardium edge area of acute myocardial infarction (AMI) model in rats. The AMI model of rats was established. After the successful model establishment, rats were randomly divided into the sham-operated group, the model group, the Danshen-Huangqi (1 : 2) group, the Danshen-Huangqi (1 : 1) group, the Chuanxiong-Huangqi (1 : 2) group, the Danshen group, the Chuanxiong group, the Chishao group and the Shexiang Baoxin pill group, with five rats in each group. Rats in each medicated group were orally administered with drugs as per 13.5 g x kg(-1) x d(-1) once everyday for three weeks. The immunohistochemical SP method was adopted to detect the expression of vWF in myocardial tissues, and count the number of micro-vessels (MVC). The protein expression of VEGF and bFGF in myocardial tissues were determined by Western blot. The new micro-vessels stained by vWF factor could be found in the infarcted myocardium edge area of the sham-operated group, the model group and all of medicated groups. The sham-operated group show unobvious new micro-vessels in myocardial tissues. A small amount of new micro-vessels could be seen in the infarcted myocardium edge area of the model group. Whereas a larger number of micro-vessels could be seen in the infarcted myocardium edge area of all of medicated groups. The differences between the sham-operated group and the model group had statistical significance (P effect in promoting angiogenesis. Their mechanism for promoting angiogenesis may be related to the improvement of the protein expressions of VEGF and bFGF, so as to increase the contents of VEGF and bFGF and promote the angiogenesis of new vessels.

  7. Edge remap for solids

    Energy Technology Data Exchange (ETDEWEB)

    Kamm, James R.; Love, Edward; Robinson, Allen C; Young, Joseph G.; Ridzal, Denis

    2013-12-01

    We review the edge element formulation for describing the kinematics of hyperelastic solids. This approach is used to frame the problem of remapping the inverse deformation gradient for Arbitrary Lagrangian-Eulerian (ALE) simulations of solid dynamics. For hyperelastic materials, the stress state is completely determined by the deformation gradient, so remapping this quantity effectively updates the stress state of the material. A method, inspired by the constrained transport remap in electromagnetics, is reviewed, according to which the zero-curl constraint on the inverse deformation gradient is implicitly satisfied. Open issues related to the accuracy of this approach are identified. An optimization-based approach is implemented to enforce positivity of the determinant of the deformation gradient. The efficacy of this approach is illustrated with numerical examples.

  8. Exponential Increase in Relative Biological Effectiveness Along Distal Edge of a Proton Bragg Peak as Measured by Deoxyribonucleic Acid Double-Strand Breaks

    Energy Technology Data Exchange (ETDEWEB)

    Cuaron, John J., E-mail: cuaronj@mskcc.org [Memorial Sloan Kettering Cancer Center, New York, New York (United States); Chang, Chang [Texas Center for Proton Therapy, Irving, Texas (United States); Lovelock, Michael; Higginson, Daniel S. [Memorial Sloan Kettering Cancer Center, New York, New York (United States); Mah, Dennis [Procure Proton Therapy Center, Somerset, New Jersey (United States); Cahlon, Oren; Powell, Simon [Memorial Sloan Kettering Cancer Center, New York, New York (United States)

    2016-05-01

    Purpose: To quantify the relative biological effectiveness (RBE) of the distal edge of the proton Bragg peak, using an in vitro assay of DNA double-strand breaks (DSBs). Methods and Materials: U2OS cells were irradiated within the plateau of a spread-out Bragg peak and at each millimeter position along the distal edge using a custom slide holder, allowing for simultaneous measurement of physical dose. A reference radiation signal was generated using photons. The DNA DSBs at 3 hours (to assess for early damage) and at 24 hours (to assess for residual damage and repair) after irradiation were measured using the γH2AX assay and quantified via flow cytometry. Results were confirmed with clonogenic survival assays. A detailed map of the RBE as a function of depth along the Bragg peak was generated using γH2AX measurements as a biological endpoint. Results: At 3 hours after irradiation, DNA DSBs were higher with protons at every point along the distal edge compared with samples irradiated with photons to similar doses. This effect was even more pronounced after 24 hours, indicating that the impact of DNA repair is less after proton irradiation relative to photons. The RBE demonstrated an exponential increase as a function of depth and was measured to be as high as 4.0 after 3 hours and as high as 6.0 after 24 hours. When the RBE-corrected dose was plotted as a function of depth, the peak effective dose was extended 2-3 mm beyond what would be expected with physical measurement. Conclusions: We generated a highly comprehensive map of the RBE of the distal edge of the Bragg peak, using a direct assay of DNA DSBs in vitro. Our data show that the RBE of the distal edge increases with depth and is significantly higher than previously reported estimates.

  9. Effects of stacking fault energies on the interaction between an edge dislocation and an 8.0-nm-diameter Frank loop of self-interstitial atoms

    Directory of Open Access Journals (Sweden)

    S. Hayakawa

    2016-12-01

    Full Text Available Molecular dynamics simulations were conducted to investigate the effects of stacking fault energy (SFE as a single variable parameter on the interaction between an edge dislocation and a Frank loop of self-interstitial atoms with a diameter of 8.0nm. The physical contact between the edge dislocation and the loop causes constriction of the edge dislocation, followed by the formation of a D-Shockley partial dislocation. The latter process is associated with either the formation of a screw component and its cross-slip, or the direct core reaction between the dislocation and the loop. These processes induce either the absorption of the loop into the dislocation or the transformation of the loop into a perfect loop. The SFE influences the interaction morphologies by determining the separation distance of the two partial dislocations and consequently the rate of constriction. The dependence of the interaction morphology on the SFE varies with the habit plane of the loop. A higher SFE increases the probability of the absorption or transformation interaction; however, only loop shearing is observed at the lower limit of the SFE range of austenitic stainless steels.

  10. Exogenous Antioxidants—Double-Edged Swords in Cellular Redox State: Health Beneficial Effects at Physiologic Doses versus Deleterious Effects at High Doses

    Directory of Open Access Journals (Sweden)

    Jaouad Bouayed

    2010-01-01

    Full Text Available The balance between oxidation and antioxidation is believed to be critical in maintaining healthy biological systems. Under physiological conditions, the human antioxidative defense system including e.g., superoxide dismutase (SOD, catalase (CAT, glutathione peroxidase (GPx, glutathione (GSH and others, allows the elimination of excess reactive oxygen species (ROS including, among others superoxide anions (O2.-, hydroxyl radicals (OH., alkoxyl radicals (RO. and peroxyradicals (ROO.. However, our endogenous antioxidant defense systems are incomplete without exogenous originating reducing compounds such as vitamin C, vitamin E, carotenoids and polyphenols, playing an essential role in many antioxidant mechanisms in living organisms. Therefore, there is continuous demand for exogenous antioxidants in order to prevent oxidative stress, representing a disequilibrium redox state in favor of oxidation. However, high doses of isolated compounds may be toxic, owing to prooxidative effects at high concentrations or their potential to react with beneficial concentrations of ROS normally present at physiological conditions that are required for optimal cellular functioning. This review aims to examine the double-edged effects of dietary originating antioxidants with a focus on the most abundant compounds, especially polyphenols, vitamin C, vitamin E and carotenoids. Different approaches to enrich our body with exogenous antioxidants such as via synthetic antioxidants, diets rich in fruits and vegetables and taking supplements will be reviewed and experimental and epidemiological evidences discussed, highlighting that antioxidants at physiological doses are generally safe, exhibiting interesting health beneficial effects.

  11. Effect of misaligned edges and magnetic field orientation on plasma deposition into gaps during ELMs on ITER

    Czech Academy of Sciences Publication Activity Database

    Dejarnac, Renaud; Komm, Michael; Gunn, J. P.; Pekarek, Z.

    2011-01-01

    Roč. 415, č. 1 (2011), S977-S980 ISSN 0022-3115. [International Conference on Plasma-Surface Interactions in Controlled Fusion (PSI19)/19th./. San Diego, 24.05.2010-28.05.2010] Institutional research plan: CEZ:AV0Z20430508 Keywords : Edge modeling * Plasma-wall interactions * ITER * Sheaths * ELMs Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 2.052, year: 2011 http://www.sciencedirect.com/science/article/pii/S0022311510005520

  12. Effect of centre-edge angle on clinical and quality of life outcomes after arthroscopic acetabular labral debridement.

    Science.gov (United States)

    Wu, Ziying; Chen, Shiyi; Li, Yunxia; Li, Hong; Chen, Jiwu

    2016-07-01

    The aim of this study was to compare clinical and quality of life outcomes following arthroscopic acetabular labral debridement between patients with different centre-edge (CE) angle. A total of 79 patients who underwent hip labral debridement were enrolled in this study. Radiographic measurements of CE angle were collected, and patients were assigned into a normal group (25°  0.05). Additionally, there was a greater improvement in clinical scores post-operatively in the normal group compared with the dysplasia group (P 25° compared with patients with CE angle < 20°.

  13. Effectiveness and tolerability of second-line therapy with vildagliptin vs. other oral agents in type 2 diabetes: A real-life worldwide observational study (EDGE)

    Science.gov (United States)

    Mathieu, C; Barnett, A H; Brath, H; Conget, I; de Castro, J J; Göke, R; Márquez Rodriguez, E; Nilsson, P M; Pagkalos, E; Penfornis, A; Schaper, NC; Wangnoo, S K; Kothny, W; Bader, G

    2013-01-01

    Aim Real-life studies are needed to confirm the clinical relevance of findings from randomised controlled trials (RCTs). This study aimed to assess the effectiveness and tolerability of vildagliptin add-on vs. other oral antihyperglycaemic drugs (OADs) added to OAD monotherapy in a real-life setting, and to explore the advantages and limitations of large-scale ‘pragmatic’ trials. Methods EDGE was a prospective, 1-year, worldwide, real-life observational study in which 2957 physicians reported on the effects of second-line OADs in 45,868 patients with T2DM not reaching glycaemic targets with monotherapy. Physicians could add any OAD, and patients entered either vildagliptin or (pooled) comparator cohort. The primary effectiveness and tolerability end-point (PEP) evaluated proportions of patients decreasing HbA1c > 0.3%, without hypoglycaemia, weight gain, peripheral oedema or gastrointestinal side effects. The most clinically relevant secondary end-point (SEP 3) was attainment of end-point HbA1c vildagliptin-based regimen. The adjusted odds ratio was 1.49 (95% CI: 1.42, 1.55; p vildagliptin-based combination and by 23% of those receiving comparator combinations. The adjusted odds ratio was 1.96 (95% CI: 1.85, 2.07; p vildagliptin and other OADs were consistent with previous data. Conclusion EDGE demonstrates that in a ‘real-life’ setting, vildagliptin as second OAD can lower HbA1c to target without well-recognised OAD side effects, more frequently than comparator OADs. In addition, EDGE illustrates that conducting large-scale, prospective, real-life studies poses challenges but yields valuable clinical information complementary to RCTs. PMID:23961850

  14. Facilitative Effect of a Generalist Herbivore on the Recovery of a Perennial Alga: Consequences for Persistence at the Edge of Their Geographic Range.

    Science.gov (United States)

    Aguilera, Moisés A; Valdivia, Nelson; Broitman, Bernardo R

    2015-01-01

    Understanding the impacts of consumers on the abundance, growth rate, recovery and persistence of their resources across their distributional range can shed light on the role of trophic interactions in determining species range shifts. Here, we examined if consumptive effects of the intertidal grazer Scurria viridula positively influences the abundance and recovery from disturbances of the alga Mazzaella laminarioides at the edge of its geographic distributions in northern-central Chilean rocky shores. Through field experiments conducted at a site in the region where M. laminarioides overlaps with the polar range edge of S. viridula, we estimated the effects of grazing on different life stages of M. laminarioides. We also used long-term abundance surveys conducted across ~700 km of the shore to evaluate co-occurrence patterns of the study species across their range overlap. We found that S. viridula had positive net effects on M. laminarioides by increasing its cover and re-growth from perennial basal crusts. Probability of occurrence of M. laminarioides increased significantly with increasing density of S. viridula across the range overlap. The negative effect of S. viridula on the percentage cover of opportunistic green algae-shown to compete for space with corticated algae-suggests that competitive release may be part of the mechanism driving the positive effect of the limpet on the abundance and recovery from disturbance of M. laminarioides. We suggest that grazer populations contribute to enhance the abundance of M. laminarioides, facilitating its recolonization and persistence at its distributional range edge. Our study highlights that indirect facilitation can determine the recovery and persistence of a resource at the limit of its distribution, and may well contribute to the ecological mechanisms governing species distributions and range shifts.

  15. Facilitative Effect of a Generalist Herbivore on the Recovery of a Perennial Alga: Consequences for Persistence at the Edge of Their Geographic Range.

    Directory of Open Access Journals (Sweden)

    Moisés A Aguilera

    Full Text Available Understanding the impacts of consumers on the abundance, growth rate, recovery and persistence of their resources across their distributional range can shed light on the role of trophic interactions in determining species range shifts. Here, we examined if consumptive effects of the intertidal grazer Scurria viridula positively influences the abundance and recovery from disturbances of the alga Mazzaella laminarioides at the edge of its geographic distributions in northern-central Chilean rocky shores. Through field experiments conducted at a site in the region where M. laminarioides overlaps with the polar range edge of S. viridula, we estimated the effects of grazing on different life stages of M. laminarioides. We also used long-term abundance surveys conducted across ~700 km of the shore to evaluate co-occurrence patterns of the study species across their range overlap. We found that S. viridula had positive net effects on M. laminarioides by increasing its cover and re-growth from perennial basal crusts. Probability of occurrence of M. laminarioides increased significantly with increasing density of S. viridula across the range overlap. The negative effect of S. viridula on the percentage cover of opportunistic green algae-shown to compete for space with corticated algae-suggests that competitive release may be part of the mechanism driving the positive effect of the limpet on the abundance and recovery from disturbance of M. laminarioides. We suggest that grazer populations contribute to enhance the abundance of M. laminarioides, facilitating its recolonization and persistence at its distributional range edge. Our study highlights that indirect facilitation can determine the recovery and persistence of a resource at the limit of its distribution, and may well contribute to the ecological mechanisms governing species distributions and range shifts.

  16. Object detection using categorised 3D edges

    DEFF Research Database (Denmark)

    Kiforenko, Lilita; Buch, Anders Glent; Bodenhagen, Leon

    2015-01-01

    is made possible by the explicit use of edge categories in the feature descriptor. We quantitatively compare our approach with the state-of-the-art template based Linemod method, which also provides an effective way of dealing with texture-less objects, tests were performed on our own object dataset. Our...... categorisation algorithm for describing objects in terms of its different edge types. Relying on edge information allow our system to deal with objects with little or no texture or surface variation. We show that edge categorisation improves matching performance due to the higher level of discrimination, which...

  17. Gate-last TiN/HfO2 band edge effective work functions using low-temperature anneals and selective cladding to control interface composition

    KAUST Repository

    Hinkle, C. L.

    2012-04-09

    Silicon N-metal-oxide-semiconductor (NMOS) and P-metal-oxide-semiconductor (PMOS) band edge effective work functions and the correspondingly low threshold voltages (Vt) are demonstrated using standard fab materials and processes in a gate-last scheme employing low-temperature anneals and selective cladding layers. Al diffusion from the cladding to the TiN/HfO2interface during forming gas anneal together with low O concentration in the TiN enables low NMOS Vt. The use of non-migrating W cladding along with experimentally detected N-induced dipoles, produced by increased oxygen in the TiN, facilitates low PMOS Vt.

  18. Gate-last TiN/HfO2 band edge effective work functions using low-temperature anneals and selective cladding to control interface composition

    KAUST Repository

    Hinkle, C. L.; Galatage, R. V.; Chapman, R. A.; Vogel, E. M.; Alshareef, Husam N.; Freeman, C.; Christensen, M.; Wimmer, E.; Niimi, H.; Li-Fatou, A.; Shaw, J. B.; Chambers, J. J.

    2012-01-01

    Silicon N-metal-oxide-semiconductor (NMOS) and P-metal-oxide-semiconductor (PMOS) band edge effective work functions and the correspondingly low threshold voltages (Vt) are demonstrated using standard fab materials and processes in a gate-last scheme employing low-temperature anneals and selective cladding layers. Al diffusion from the cladding to the TiN/HfO2interface during forming gas anneal together with low O concentration in the TiN enables low NMOS Vt. The use of non-migrating W cladding along with experimentally detected N-induced dipoles, produced by increased oxygen in the TiN, facilitates low PMOS Vt.

  19. Effect of progressively increasing lithium conditioning on edge transport and stability in high triangularity NSTX H-modes

    Energy Technology Data Exchange (ETDEWEB)

    Maingi, R., E-mail: rmaingi@pppl.gov [Princeton Plasma Physics Laboratory, 100 Stellarator Road, Princeton, NJ 08543 (United States); Canik, J.M. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Bell, R.E. [Princeton Plasma Physics Laboratory, 100 Stellarator Road, Princeton, NJ 08543 (United States); Boyle, D.P. [Princeton University, Princeton, NJ (United States); Diallo, A.; Kaita, R.; Kaye, S.M.; LeBlanc, B.P. [Princeton Plasma Physics Laboratory, 100 Stellarator Road, Princeton, NJ 08543 (United States); Sabbagh, S.A. [Columbia University, New York, NY (United States); Scotti, F.; Soukhanovskii, V.A. [Lawrence Livermore National Laboratory, Livermore, CA (United States)

    2017-04-15

    A sequence of H-mode discharges with increasing levels of pre-discharge lithium evaporation (‘dose’) was conducted in high triangularity and elongation boundary shape in NSTX. Energy confinement increased, and recycling decreased with increasing lithium dose, similar to a previous lithium dose scan in medium triangularity and elongation plasmas. Data-constrained SOLPS interpretive modeling quantified the edge transport change: the electron particle diffusivity decreased by 10–30x. The electron thermal diffusivity decreased by 4x just inside the top of the pedestal, but increased by up to 5x very near the separatrix. These results provide a baseline expectation for lithium benefits in NSTX-U, which is optimized for a boundary shape similar to the one in this experiment.

  20. Finite-size effects on electronic structure and local properties in passivated AA -stacked bilayer armchair-edge graphene nanoribbons

    International Nuclear Information System (INIS)

    Chen, Xiongwen; Shi, Zhengang; Xiang, Shaohua; Song, Kehui; Zhou, Guanghui

    2017-01-01

    Based on the tight-binding model and dual-probe scanning tunneling microscopy technology, we theoretically investigate the electronic structure and local property in the passivated AA -stacked bilayer armchair-edge graphene nanoribbons (AABLAGNRs). We show that they are highly sensitive to the size of the ribbons, which is evidently different from the single-layer armchair-edge graphene nanoribbons. The ‘3 p ’ rule only applies to the narrow AABLGNRs. Namely, in the passivated 3 p - and (3 p   +  1)-AABLGNRs, the narrow ribbons are semiconducting while the medium and wide ribbons are metallic. Although the passivated (3 p   +  2)-AABLGNRs are metallic, the ‘3 j ’ rule only applies to the narrow and medium ribbons. Namely, electrons are in the semiconducting states at sites of line 3 j while they are in the metallic states at other sites. This induces a series of parallel and discrete metallic channels, consisting of lines 3 j   −  1 and 3 j   −  2, for the low-energy electronic transports. In the passivated wide (3 p   +  2)-AABLGNRs, all electrons are in the metallic states. Additionally, the ‘3 p ’ and ‘3 j ’ rules are controllable to disappear and reappear by applying an external perpendicular electric field. Resultantly, an electric filed-driven current switch can be realized in the passivated narrow and medium (3 p   +  2)-AABLGNRs. (paper)

  1. Electric field effect on the magnetic properties of zigzag MoS2 nanoribbons with different edge passivation.

    Science.gov (United States)

    Nam, Yeonsig; Cho, Daeheum; Lee, Jin Yong

    2017-11-22

    Electrical control of magnetic exchange coupling interactions is central to designing magnetic materials. In this study, we performed density functional theory calculations to investigate the magnetic spin configuration, magnetic moment, and magnetic coupling strength of zigzag MoS 2 nanoribbons (zMoS 2 NRs) with different edge passivation, that is, pristine (Pristine), hydrogen termination (H-tem), sulfur termination (S-term), and sulfhydryl termination (SH-term). Further, we investigated the influence of an external electric field (F Ext ) on the magnetic properties. Pristine and H-term showed an AFM ground configuration with considerably weak magnetic coupling strength while S-term and SH-term showed a single edge FM ground configuration in the absence of the electric field. When the external electric field was applied, the positive field intensified the original spin configuration, thus increasing the magnetic moment of the system while the negative field weakened the original spin configuration, thus decreasing the magnetic moment and further reversed the spin configuration from AFM to FM and vice versa in most systems. The magnetic coupling strength of the system increased for both Pristine and H-term regardless of the direction of the field. However, the extent of increase was much higher in Pristine due to the existence of relatively easily transferable dangling electrons compared with the constrained electrons of H-term restricted to chemical bonds. Our results demonstrate a possibility of reversible spin control from AFM to FM and vice versa by applying an electric field and the enhancement of the magnetic coupling strength of zMoS 2 NRs.

  2. Edge enhancement improves disruptive camouflage by emphasising false edges and creating pictorial relief.

    Science.gov (United States)

    Egan, John; Sharman, Rebecca J; Scott-Brown, Kenneth C; Lovell, Paul George

    2016-12-06

    Disruptive colouration is a visual camouflage composed of false edges and boundaries. Many disruptively camouflaged animals feature enhanced edges; light patches are surrounded by a lighter outline and/or a dark patches are surrounded by a darker outline. This camouflage is particularly common in amphibians, reptiles and lepidopterans. We explored the role that this pattern has in creating effective camouflage. In a visual search task utilising an ultra-large display area mimicking search tasks that might be found in nature, edge enhanced disruptive camouflage increases crypsis, even on substrates that do not provide an obvious visual match. Specifically, edge enhanced camouflage is effective on backgrounds both with and without shadows; i.e. this is not solely due to background matching of the dark edge enhancement element with the shadows. Furthermore, when the dark component of the edge enhancement is omitted the camouflage still provided better crypsis than control patterns without edge enhancement. This kind of edge enhancement improved camouflage on all background types. Lastly, we show that edge enhancement can create a perception of multiple surfaces. We conclude that edge enhancement increases the effectiveness of disruptive camouflage through mechanisms that may include the improved disruption of the object outline by implying pictorial relief.

  3. Edge colouring by total labellings

    DEFF Research Database (Denmark)

    Brandt, Stephan; Rautenbach, D.; Stiebitz, M.

    2010-01-01

    We introduce the concept of an edge-colouring total k-labelling. This is a labelling of the vertices and the edges of a graph G with labels 1, 2, ..., k such that the weights of the edges define a proper edge colouring of G. Here the weight of an edge is the sum of its label and the labels of its...

  4. Edge-detect interpolation for direct digital periapical images

    International Nuclear Information System (INIS)

    Song, Nam Kyu; Koh, Kwang Joon

    1998-01-01

    The purpose of this study was to aid in the use of the digital images by edge-detect interpolation for direct digital periapical images using edge-deted interpolation. This study was performed by image processing of 20 digital periapical images; pixel replication, linear non-interpolation, linear interpolation, and edge-sensitive interpolation. The obtained results were as follows ; 1. Pixel replication showed blocking artifact and serious image distortion. 2. Linear interpolation showed smoothing effect on the edge. 3. Edge-sensitive interpolation overcame the smoothing effect on the edge and showed better image.

  5. Waning habitats due to climate change: the effects of changes in streamflow and temperature at the rear edge of the distribution of a cold-water fish

    Directory of Open Access Journals (Sweden)

    J. M. Santiago

    2017-08-01

    Full Text Available Climate changes affect aquatic ecosystems by altering temperatures and precipitation patterns, and the rear edges of the distributions of cold-water species are especially sensitive to these effects. The main goal of this study was to predict in detail how changes in air temperature and precipitation will affect streamflow, the thermal habitat of a cold-water fish (the brown trout, Salmo trutta, and the synergistic relationships among these variables at the rear edge of the natural distribution of brown trout. Thirty-one sites in 14 mountain rivers and streams were studied in central Spain. Models of streamflow were built for several of these sites using M5 model trees, and a non-linear regression method was used to estimate stream temperatures. Nine global climate models simulations for Representative Concentration Pathways RCP4.5 and RCP8.5 scenarios were downscaled to the local level. Significant reductions in streamflow were predicted to occur in all of the basins (max. −49 % by the year 2099, and seasonal differences were noted between the basins. The stream temperature models showed relationships between the model parameters, geology and hydrologic responses. Temperature was sensitive to streamflow in one set of streams, and summer reductions in streamflow contributed to additional stream temperature increases (max. 3.6 °C, although the sites that are most dependent on deep aquifers will likely resist warming to a greater degree. The predicted increases in water temperatures were as high as 4.0 °C. Temperature and streamflow changes will cause a shift in the rear edge of the distribution of this species. However, geology will affect the extent of this shift. Approaches like the one used herein have proven to be useful in planning the prevention and mitigation of the negative effects of climate change by differentiating areas based on the risk level and viability of fish populations.

  6. Waning habitats due to climate change: the effects of changes in streamflow and temperature at the rear edge of the distribution of a cold-water fish

    Science.gov (United States)

    María Santiago, José; Muñoz-Mas, Rafael; Solana-Gutiérrez, Joaquín; García de Jalón, Diego; Alonso, Carlos; Martínez-Capel, Francisco; Pórtoles, Javier; Monjo, Robert; Ribalaygua, Jaime

    2017-08-01

    Climate changes affect aquatic ecosystems by altering temperatures and precipitation patterns, and the rear edges of the distributions of cold-water species are especially sensitive to these effects. The main goal of this study was to predict in detail how changes in air temperature and precipitation will affect streamflow, the thermal habitat of a cold-water fish (the brown trout, Salmo trutta), and the synergistic relationships among these variables at the rear edge of the natural distribution of brown trout. Thirty-one sites in 14 mountain rivers and streams were studied in central Spain. Models of streamflow were built for several of these sites using M5 model trees, and a non-linear regression method was used to estimate stream temperatures. Nine global climate models simulations for Representative Concentration Pathways RCP4.5 and RCP8.5 scenarios were downscaled to the local level. Significant reductions in streamflow were predicted to occur in all of the basins (max. -49 %) by the year 2099, and seasonal differences were noted between the basins. The stream temperature models showed relationships between the model parameters, geology and hydrologic responses. Temperature was sensitive to streamflow in one set of streams, and summer reductions in streamflow contributed to additional stream temperature increases (max. 3.6 °C), although the sites that are most dependent on deep aquifers will likely resist warming to a greater degree. The predicted increases in water temperatures were as high as 4.0 °C. Temperature and streamflow changes will cause a shift in the rear edge of the distribution of this species. However, geology will affect the extent of this shift. Approaches like the one used herein have proven to be useful in planning the prevention and mitigation of the negative effects of climate change by differentiating areas based on the risk level and viability of fish populations.

  7. Adobe Edge Quickstart Guide

    CERN Document Server

    Labrecque, Joseph

    2012-01-01

    Adobe Edge Quickstart Guide is a practical guide on creating engaging content for the Web with Adobe's newest HTML5 tool. By taking a chapter-by-chapter look at each major aspect of Adobe Edge, the book lets you digest the available features in small, easily understandable chunks, allowing you to start using Adobe Edge for your web design needs immediately. If you are interested in creating engaging motion and interactive compositions using web standards with professional tooling, then this book is for you. Those with a background in Flash Professional wanting to get started quickly with Adobe

  8. Effectiveness and tolerability of second-line therapy with vildagliptin versus other oral agents in type 2 diabetes (EDGE): post-hoc subanalysis of the Belgian data.

    Science.gov (United States)

    Hoste, J; Daci, E; Mathieu, C

    2014-06-01

    To assess the efficacy and safety of vildagliptin versus other oral glucose-lowering drugs added to antidiabetic monotherapy in Belgian patients with type 2 diabetes mellitus, in comparison to the global EDGE study results. This is a pre-specified post-hoc subanalysis of the Belgian patient cohort from a worldwide 1-year observational study that compared the effectiveness and tolerability of vildagliptin to other oral antidiabetic agents in type 2 diabetes patients failing monotherapy with oral glucose-lowering agents (EDGE). A total of 1793 Belgian patients were enrolled. Physicians could add any oral antidiabetic drug and patients entered either into the vildagliptin or the comparator cohort. The primary effectiveness and tolerability endpoint was defined as the proportion of patients having a treatment response (HbA1c reduction from baseline to month 12 endpoint >0·3%) without hypoglycemia, weight gain, peripheral oedema, or gastrointestinal side-effects. In the Belgian population, 37·8% of patients in the vildagliptin group and 32·8% in the comparator group had a decrease in HbA1c of >0·3% without the predefined tolerability issues of hypoglycemia, weight gain, oedema or, gastrointestinal complaints (primary endpoint), resulting in an unadjusted odds ratio of 1·24 (95% CI: 0·96-1·61). Mean HbA1c change from baseline was -0·81% in the vildagliptin cohort and -0·75% in the comparator cohort. Overall, vildagliptin was well tolerated with similarly low incidences of total adverse events (14·9% versus 14·5% in the compactor group) and serious adverse events (2·7% versus 2·5% in the comparator group). In this EDGE subgroup of Belgian patients with type 2 diabetes who do not achieve the glycemic targets with monotherapy, a similar trend as in the global EDGE study was observed. Adding vildagliptin as a second oral glucose-lowering agent resulted in lowering HbA1c to <7% without weight gain, hypoglycemia or peripheral oedema in a higher proportion of

  9. Adobe Edge Preview 3

    CERN Document Server

    Grover, Chris

    2011-01-01

    Want to use an Adobe tool to design animated web graphics that work on iPhone and iPad? You've come to the right book. Adobe Edge Preview 3: The Missing Manual shows you how to build HTML5 graphics using simple visual tools. No programming experience? No problem. Adobe Edge writes the underlying code for you. With this eBook, you'll be designing great-looking web elements in no time. Get to know the workspace. Learn how Adobe Edge Preview 3 performs its magic.Create and import graphics. Make drawings with Edge's tools, or use art you designed in other programs.Work with text. Build menus, lab

  10. Pavement edge treatment.

    Science.gov (United States)

    2013-01-01

    Four projects were built over two construction seasons using special devices attached to the paving machine that produces a 30 slope on the outside pavement edge instead of the near vertical drop-off common with conventional paving equipment. This ...

  11. Edge Simulation Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Krasheninnikov, Sergei I. [Univ. of California, San Diego, CA (United States); Angus, Justin [Univ. of California, San Diego, CA (United States); Lee, Wonjae [Univ. of California, San Diego, CA (United States)

    2018-01-05

    The goal of the Edge Simulation Laboratory (ESL) multi-institutional project is to advance scientific understanding of the edge plasma region of magnetic fusion devices via a coordinated effort utilizing modern computing resources, advanced algorithms, and ongoing theoretical development. The UCSD team was involved in the development of the COGENT code for kinetic studies across a magnetic separatrix. This work included a kinetic treatment of electrons and multiple ion species (impurities) and accurate collision operators.

  12. Diagnostic accuracy of fracture detection in suspected non-accidental injury: the effect of edge enhancement and digital display on observer performance

    Energy Technology Data Exchange (ETDEWEB)

    Offiah, A.C. [Department of Radiology, Great Ormond Street Hospital for Children, London (United Kingdom) and Institute of Child Health, London (United Kingdom)]. E-mail: amaka.offiah@gosh.nhs.uk; Moon, L. [Department of Radiology, Great Ormond Street Hospital for Children, London (United Kingdom); Hall, C.M. [Department of Radiology, Great Ormond Street Hospital for Children, London (United Kingdom); Todd-Pokropek, A. [Department of Medical Physics and Bioengineering, University College London, London (United Kingdom)

    2006-02-15

    AIM: To compare the effect of varying degrees of edge enhancement and method of digital image display on fracture detection in suspected non-accidental injury (NAI). MATERIALS AND METHODS: Fifty radiographs from post-mortem skeletal surveys in 13 children with suspected NAI were selected. Images were obtained using a Fuji 5000R computed radiography system. Hard copies were printed with edge enhancement factors 0, 0.5 and 1.2. Images (edge enhancement 0.5) were also displayed on a 1K{sup 2} monitor. Six observers independently evaluated all 200 images for the presence of abnormality. Observers also scored each image for visualization of soft tissues, visualization of trabecular markings and overall image quality. The paired Student's t-test and location receiver operating curve (ROC) analysis were used to compare quality scores and diagnostic accuracy of each display method. Individual and pooled true-positive rates (sensitivity) were determined. For the purposes of ROC analysis, histology was taken as the gold standard. RESULTS: There was no difference in duration of hard and soft-copy reading sessions (p=0.76). After image manipulation soft-copy radiographs scored significantly better for image quality than hard copy (p<0.0001). Pooled observer sensitivity (at a specificity of 90%) was below 50% for all display methods. Diagnostic accuracy varied significantly between observers. Diagnostic accuracy of individual observers was not affected by display method. CONCLUSION: In suspected NAI, diagnostic accuracy of fracture detection is generally low. Diagnostic accuracy appears to be affected more by observer-related factors than by the method of digital image display.

  13. Use of a silicon surface-barrier detector for measurement of high-energy end loss electrons in a tandem mirror

    International Nuclear Information System (INIS)

    Saito, T.; Kiwamoto, Y.; Honda, T.; Kasugai, A.; Kurihara, K.; Miyoshi, S.

    1991-01-01

    An apparatus for the measurement of high-energy electrons (10--500 keV) with a silicon surface-barrier detector is described. The apparatus has special features. In particular, a fast CAMAC transient digitizer is used to directly record the wave form of a pulse train from the detector and then pulse heights are analyzed with a computer instead of on a conventional pulse height analyzer. With this method the system is capable of detecting electrons with a count rate as high as ∼300--400 kilocounts/s without serious deterioration of performance. Moreover, piled up signals are reliably eliminated from analysis. The system has been applied to measure electron-cyclotron-resonance-heating-induced end loss electrons in the GAMMA 10 tandem mirror and has yielded information relating to electron heating and diffusion in velocity space

  14. Two very long chain fatty acid acyl-CoA synthetase genes, acs-20 and acs-22, have roles in the cuticle surface barrier in Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Eriko Kage-Nakadai

    Full Text Available In multicellular organisms, the surface barrier is essential for maintaining the internal environment. In mammals, the barrier is the stratum corneum. Fatty acid transport protein 4 (FATP4 is a key factor involved in forming the stratum corneum barrier. Mice lacking Fatp4 display early neonatal lethality with features such as tight, thick, and shiny skin, and a defective skin barrier. These symptoms are strikingly similar to those of a human skin disease called restrictive dermopathy. FATP4 is a member of the FATP family that possesses acyl-CoA synthetase activity for very long chain fatty acids. How Fatp4 contributes to skin barrier function, however, remains to be elucidated. In the present study, we characterized two Caenorhabditis elegans genes, acs-20 and acs-22, that are homologous to mammalian FATPs. Animals with mutant acs-20 exhibited defects in the cuticle barrier, which normally prevents the penetration of small molecules. acs-20 mutant animals also exhibited abnormalities in the cuticle structure, but not in epidermal cell fate or cell integrity. The acs-22 mutants rarely showed a barrier defect, whereas acs-20;acs-22 double mutants had severely disrupted barrier function. Moreover, the barrier defects of acs-20 and acs-20;acs-22 mutants were rescued by acs-20, acs-22, or human Fatp4 transgenes. We further demonstrated that the incorporation of exogenous very long chain fatty acids into sphingomyelin was reduced in acs-20 and acs-22 mutants. These findings indicate that C. elegans Fatp4 homologue(s have a crucial role in the surface barrier function and this model might be useful for studying the fundamental molecular mechanisms underlying human skin barrier and relevant diseases.

  15. The ship edge feature detection based on high and low threshold for remote sensing image

    Science.gov (United States)

    Li, Xuan; Li, Shengyang

    2018-05-01

    In this paper, a method based on high and low threshold is proposed to detect the ship edge feature due to the low accuracy rate caused by the noise. Analyze the relationship between human vision system and the target features, and to determine the ship target by detecting the edge feature. Firstly, using the second-order differential method to enhance the quality of image; Secondly, to improvement the edge operator, we introduction of high and low threshold contrast to enhancement image edge and non-edge points, and the edge as the foreground image, non-edge as a background image using image segmentation to achieve edge detection, and remove the false edges; Finally, the edge features are described based on the result of edge features detection, and determine the ship target. The experimental results show that the proposed method can effectively reduce the number of false edges in edge detection, and has the high accuracy of remote sensing ship edge detection.

  16. [Effects of increased precipitation on the water use of Nitraira tangutorum at southeast edge of Baddain Jaran Desert in China].

    Science.gov (United States)

    Zhu, Ya-Juan; Lu, Qi; Wu, Bo; Li, Yong-Hua; Yao, Bin; Zhang, Jin-Xin

    2013-01-01

    This paper studied the threshold value of the water use of Nitraria tanturorum shrubs at the southeast edge of Baddain Jiran Desert. From the early May to late September in 2009, an irrigation simulating increased precipitation was conducted once every month. Three ratios of increased precipitation (0, 50% and 100%) were designed, based on the local mean annual precipitation (115 mm). On the 1 day before irrigation and the 1, 3 and 7 days after irrigation in May, July and September, the deltaD in the xylem water of N. tangutorum, the soil water at the depths 10 and 30 cm, and the well water and natural rainfall, and the variations of the soil water content were measured. Under natural condition, the N. tangutorum mainly utilize ground water in May and September, and utilize the soil water at the depths 10 and 30 cm in July. After irrigation, the ground water use rate of the N. tangutorum decreased, while the soil water use rate increased. In the treatment of 100% increased precipitation, the deltaD ratio of the water in N. tangutorum xylem was affected significantly, and the water use of the N. tangutorum in May, July and September increased. In the treatment of 50% increased precipitation, the soil water condition in May and July was improved, but the water use rate had little improvement. Only when the increased precipitation reached 100% of the local mean annual precipitation, could the water use rate of the N. tangutorum have an obvious increase.

  17. Differential Effects of Roads and Traffic on Space Use and Movements of Native Forest-Dependent and Introduced Edge-Tolerant Species.

    Directory of Open Access Journals (Sweden)

    Hsiang Ling Chen

    Full Text Available Anthropogenic infrastructure such as roads and non-native species are major causes of species endangerment. Understanding animal behavioral responses to roads and traffic provides insight into causes and mechanisms of effects of linear development on wildlife and aids effective mitigation and conservation. We investigated effects of roads and traffic on space use and movements of two forest-dwelling species: endemic, forest-dependent Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis and introduced, edge-tolerant Abert's squirrels (Sciurus aberti. To assess the effects of roads on space use and movement patterns, we compared the probability that a squirrel home range included roads and random lines in forests, and assessed effects of traffic intensity on rate of road crossing and movement patterns. Red squirrels avoided areas adjacent to roads and rarely crossed roads. In contrast, Abert's squirrels were more likely to include roads in their home ranges compared to random lines in forests. Both red squirrels and Abert's squirrels increased speed when crossing roads, compared to before and after road crossings. Increased hourly traffic volume reduced the rate of road crossings by both species. Behavioral responses of red squirrels to roads and traffic resemble responses to elevated predation risk, including reduced speed near roads and increased tortuosity of movement paths with increased traffic volume. In contrast, Abert's squirrels appeared little affected by roads and traffic with tortuosity of movement paths reduced as distance to roads decreased. We found that species with similar body size category (<1 kg but different habitat preference and foraging strategy responded to roads differently and demonstrated that behavior and ecology are important when considering effects of roads on wildlife. Our results indicate that roads restricted movements and space use of a native forest-dependent species while creating habitat preferred

  18. Differential Effects of Roads and Traffic on Space Use and Movements of Native Forest-Dependent and Introduced Edge-Tolerant Species.

    Science.gov (United States)

    Chen, Hsiang Ling; Koprowski, John L

    2016-01-01

    Anthropogenic infrastructure such as roads and non-native species are major causes of species endangerment. Understanding animal behavioral responses to roads and traffic provides insight into causes and mechanisms of effects of linear development on wildlife and aids effective mitigation and conservation. We investigated effects of roads and traffic on space use and movements of two forest-dwelling species: endemic, forest-dependent Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis) and introduced, edge-tolerant Abert's squirrels (Sciurus aberti). To assess the effects of roads on space use and movement patterns, we compared the probability that a squirrel home range included roads and random lines in forests, and assessed effects of traffic intensity on rate of road crossing and movement patterns. Red squirrels avoided areas adjacent to roads and rarely crossed roads. In contrast, Abert's squirrels were more likely to include roads in their home ranges compared to random lines in forests. Both red squirrels and Abert's squirrels increased speed when crossing roads, compared to before and after road crossings. Increased hourly traffic volume reduced the rate of road crossings by both species. Behavioral responses of red squirrels to roads and traffic resemble responses to elevated predation risk, including reduced speed near roads and increased tortuosity of movement paths with increased traffic volume. In contrast, Abert's squirrels appeared little affected by roads and traffic with tortuosity of movement paths reduced as distance to roads decreased. We found that species with similar body size category (roads differently and demonstrated that behavior and ecology are important when considering effects of roads on wildlife. Our results indicate that roads restricted movements and space use of a native forest-dependent species while creating habitat preferred by an introduced, edge-tolerant species.

  19. Gyrosheath near the tokamak edge

    International Nuclear Information System (INIS)

    Hazeltine, R.D.; Xiao, H.; Valanju, P.M.

    1993-03-01

    A new model for the structure of the radial electric field profile in the edge during the H-mode is proposed. Charge separation caused by the difference between electron and ion gyromotion, or more importantly in a tokamak, the banana motion (halo effect) can self-consistently produce an electric dipole moment that causes the sheared radial electric field. The calculated results based on the model are consistent with D-III D and TEXTOR experimental results

  20. The Edge supersonic transport

    Science.gov (United States)

    Agosta, Roxana; Bilbija, Dushan; Deutsch, Marc; Gallant, David; Rose, Don; Shreve, Gene; Smario, David; Suffredini, Brian

    1992-01-01

    As intercontinental business and tourism volumes continue their rapid expansion, the need to reduce travel times becomes increasingly acute. The Edge Supersonic Transport Aircraft is designed to meet this demand by the year 2015. With a maximum range of 5750 nm, a payload of 294 passengers and a cruising speed of M = 2.4, The Edge will cut current international flight durations in half, while maintaining competitive first class, business class, and economy class comfort levels. Moreover, this transport will render a minimal impact upon the environment, and will meet all Federal Aviation Administration Part 36, Stage III noise requirements. The cornerstone of The Edge's superior flight performance is its aerodynamically efficient, dual-configuration design incorporating variable-geometry wingtips. This arrangement combines the benefits of a high aspect ratio wing at takeoff and low cruising speeds with the high performance of an arrow-wing in supersonic cruise. And while the structural weight concerns relating to swinging wingtips are substantial, The Edge looks to ever-advancing material technologies to further increase its viability. Heeding well the lessons of the past, The Edge design holds economic feasibility as its primary focus. Therefore, in addition to its inherently superior aerodynamic performance, The Edge uses a lightweight, largely windowless configuration, relying on a synthetic vision system for outside viewing by both pilot and passengers. Additionally, a fly-by-light flight control system is incorporated to address aircraft supersonic cruise instability. The Edge will be produced at an estimated volume of 400 aircraft and will be offered to airlines in 2015 at $167 million per transport (1992 dollars).