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Sample records for demonstration erosion control

  1. Emergency wind erosion control

    Science.gov (United States)

    February through May is the critical time for wind erosion in Kansas, but wind erosion can happen any time when high winds occur on smooth, wide fields with low vegetation and poor soil structure. The most effective wind erosion control is to ensure a protective cover of residue or growing crop thro...

  2. Coastal Erosion Control Methods

    Science.gov (United States)

    Greene, V.

    2016-12-01

    Coastal erosion is bad because the ecosystem there will be washed away and the animals could drown or be displaced and have to adapt to a new ecosystem that they are not prepared for. I'm interested in this problem because if there aren't beaches when I grow up I won't be able to do the things I would really like to do. I would like to be a marine biologist. Secondly, I don't want to see beach houses washed away. I would like to see people live in harmony with their environment. So, to study ways in which to preserve beaches I will make and use models that test different erosion controls. Two different ideas for erosion control I tested are using seaweed or a rock berm. I think the rock berm will work better than the model of seaweed because the seaweed is under water and the waves can carry the sand over the seaweed, and the rock berm will work better because the rocks will help break the waves up before they reach the shore and the waves can not carry the sand over the rocks that are above the water. To investigate this I got a container to use to model the Gulf of Mexico coastline. I performed several test runs using sand and water in the container to mimic the beach and waves from the Gulf of Mexico hitting the shoreline. I did three trials for the control (no erosion control), seaweed and a rock berm. Rock berms are a border of a raised area of rock. The model for seaweed that I used was plastic shopping bags cut into strips and glued to the bottom of my container to mimic seaweed. My results were that the control had the most erosion which ranged from 2.75 - 3 inches over 3 trials. The seaweed was a little better than the control but was very variable and ranged from 1.5 - 3 inches over 3 trials. The rock berm worked the best out of all at controlling erosion with erosion ranging from 1.5 - 2 inches. My hypothesis was correct because the rock berm did best to control erosion compared to the control which had no erosion control and the model with seaweed.

  3. Can control of soil erosion mitigate water pollution by sediments?

    Science.gov (United States)

    Rickson, R J

    2014-01-15

    The detrimental impact of sediment and associated pollutants on water quality is widely acknowledged, with many watercourses in the UK failing to meet the standard of 'good ecological status'. Catchment sediment budgets show that hill slope erosion processes can be significant sources of waterborne sediment, with rates of erosion likely to increase given predicted future weather patterns. However, linking on-site erosion rates with off-site impacts is complicated because of the limited data on soil erosion rates in the UK and the dynamic nature of the source-pathway-receptor continuum over space and time. Even so, soil erosion control measures are designed to reduce sediment production (source) and mobilisation/transport (pathway) on hill slopes, with consequent mitigation of pollution incidents in watercourses (receptors). The purpose of this paper is to review the scientific evidence of the effectiveness of erosion control measures used in the UK to reduce sediment loads of hill slope origin in watercourses. Although over 73 soil erosion mitigation measures have been identified from the literature, empirical data on erosion control effectiveness are limited. Baseline comparisons for the 18 measures where data do exist reveal erosion control effectiveness is highly variable over time and between study locations. Given the limitations of the evidence base in terms of geographical coverage and duration of monitoring, performance of the different measures cannot be extrapolated to other areas. This uncertainty in effectiveness has implications for implementing erosion/sediment risk reduction policies, where quantified targets are stipulated, as is the case in the EU Freshwater Fish and draft Soil Framework Directives. Also, demonstrating technical effectiveness of erosion control measures alone will not encourage uptake by land managers: quantifying the costs and benefits of adopting erosion mitigation is equally important, but these are uncertain and difficult to

  4. Emission Facilities - Erosion & Sediment Control Facilities

    Data.gov (United States)

    NSGIC Education | GIS Inventory — An Erosion and Sediment Control Facility is a DEP primary facility type related to the Water Pollution Control program. The following sub-facility types related to...

  5. Geophysical Processes - Erosion & Sediment Control Facilities

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — An Erosion and Sediment Control Facility is a DEP primary facility type related to the Water Pollution Control program. The following sub-facility types related to...

  6. Can we manipulate root system architecture to control soil erosion?

    Science.gov (United States)

    Ola, A.; Dodd, I. C.; Quinton, J. N.

    2015-09-01

    Soil erosion is a major threat to soil functioning. The use of vegetation to control erosion has long been a topic for research. Much of this research has focused on the above-ground properties of plants, demonstrating the important role that canopy structure and cover plays in the reduction of water erosion processes. Less attention has been paid to plant roots. Plant roots are a crucial yet under-researched factor for reducing water erosion through their ability to alter soil properties, such as aggregate stability, hydraulic function and shear strength. However, there have been few attempts to specifically manipulate plant root system properties to reduce soil erosion. Therefore, this review aims to explore the effects that plant roots have on soil erosion and hydrological processes, and how plant root architecture might be manipulated to enhance its erosion control properties. We demonstrate the importance of root system architecture for the control of soil erosion. We also show that some plant species respond to nutrient-enriched patches by increasing lateral root proliferation. The erosional response to root proliferation will depend upon its location: at the soil surface dense mats of roots may reduce soil erodibility but block soil pores thereby limiting infiltration, enhancing runoff. Additionally, in nutrient-deprived regions, root hair development may be stimulated and larger amounts of root exudates released, thereby improving aggregate stability and decreasing erodibility. Utilizing nutrient placement at specific depths may represent a potentially new, easily implemented, management strategy on nutrient-poor agricultural land or constructed slopes to control erosion, and further research in this area is needed.

  7. Field Jet Erosion Tests on the Mississippi River Collocated Demonstration Section, Plaquemines Parish, Louisiana

    Science.gov (United States)

    2015-06-01

    ER D C/ G SL T R- 15 -1 3 Field Jet Erosion Tests on the Mississippi River Collocated Demonstration Section, Plaquemines Parish...default. ERDC/GSL TR-15-13 June 2015 Field Jet Erosion Tests on the Mississippi River Collocated Demonstration Section, Plaquemines Parish...Prepared for U.S. Army Corps of Engineers Washington, DC 20314-1000 ERDC/GSL TR-15-13 ii Abstract Field jet erosion tests (JETs) were

  8. CONTROL OF GULLY EROSION USING STIFF GRASSES

    Institute of Scientific and Technical Information of China (English)

    F. D. SHIELDS, Jr.; S. M. DABNEY; E. J. LANGENDOEN; D. M. TEMPLE

    2005-01-01

    Concentrated flow can cause gully formation on sloping lands and in riparian zones. Current practice for riparian gully erosion control involves blocking the gully with a structure comprised of an earthen embankment and a metal or plastic pipe. Measures involving native vegetation would be more attractive for habitat recovery and economic reasons. To test the hypothesis that switchgrass (Panicum virgatum L.) hedges planted at 0.5-m vertical intervals within a gully would control erosion,a series of hedges was established in four concentrated flow channels. Two of the channels were previously eroded trapezoidal channels cut into compacted fill in an outdoor laboratory. The other two channels were natural gullies located at the edge of floodplain fields adjacent to an incised stream.While vegetation was dormant, artificial runoff events were created in the two laboratory gullies and one of the natural gullies using synthetic trapezoidal-shaped hydrographs with peak discharge rates of approximately 0.03, 0.07, and 0.16 m3/s. During these tests flow depth, velocity, turbidity, and soil pore water pressures were monitored. The fourth gully was subjected to a series of natural runoff events over a five-month period with peaks up to 0.09 m3/s. Flow depths in all tests were generally < 0.3 m, and flow velocities varied spatially and exceeded 2.0 m/s at the steepest points of the gullies.Erosion rates were negligible for controlled flow experiments, but natural flows in the fourth gully resulted in 1 m of thalweg degradation, destroying the central portions of the grass hedges, most likely due to the highly erodible nature of the soils at this site. Geotechnical modeling of soil steps reinforced with switchgrass roots showed factors of safety > 1 for step heights < 0.5 m, but instability was indicated for step heights > 1 m, consistent with the experimental observations.

  9. Buhne Point Shoreline Erosion Demonstration Project. Volume 2. Appendices E.

    Science.gov (United States)

    1987-08-01

    indoo -ne mranr.port c., beach material in the study area. Hoiw.-ver, durinq stro. J north-:erly and northweste-rly wind~s. it ,as beer n: scr.,ed thaL...alternate features were :natvzed in more detail to more confidently1assess comparativi= qualities . Little comparative dif-ference ias found between...construction of D’uhne Point Road; and coordin- ation with Coastal Zone Commission and Regional Water Quality Control Board. The following persons have

  10. Robotic weld overlay coatings for erosion control

    Science.gov (United States)

    The erosion of materials by the impact of solid particles has received increasing attention during the past twenty years. Recently, research has been initiated with the event of advanced coal conversion processes in which erosion plays an important role. The resulting damage, termed Solid Particle Erosion (SPE), is of concern primarily because of the significantly increased operating costs which result in material failures. Reduced power plant efficiency due to solid particle erosion of boiler tubes and waterfalls has led to various methods to combat SPE. One method is to apply coatings to the components subjected to erosive environments. Protective weld overlay coatings are particularly advantageous in terms of coating quality. The weld overlay coatings are essentially immune to spallation due to a strong metallurgical bond with the substrate material. By using powder mixtures, multiple alloys can be mixed in order to achieve the best performance in an erosive environment. However, a review of the literature revealed a lack of information on weld overlay coating performance in erosive environments which makes the selection of weld overlay alloys a difficult task. The objective of this project is to determine the effects of weld overlay coating composition and microstructure on erosion resistance. These results will lead to a better understanding of erosion mitigation in CFB's.

  11. Demonstration of Active Combustion Control

    Science.gov (United States)

    Lovett, Jeffrey A.; Teerlinck, Karen A.; Cohen, Jeffrey M.

    2008-01-01

    The primary objective of this effort was to demonstrate active control of combustion instabilities in a direct-injection gas turbine combustor that accurately simulates engine operating conditions and reproduces an engine-type instability. This report documents the second phase of a two-phase effort. The first phase involved the analysis of an instability observed in a developmental aeroengine and the design of a single-nozzle test rig to replicate that phenomenon. This was successfully completed in 2001 and is documented in the Phase I report. This second phase was directed toward demonstration of active control strategies to mitigate this instability and thereby demonstrate the viability of active control for aircraft engine combustors. This involved development of high-speed actuator technology, testing and analysis of how the actuation system was integrated with the combustion system, control algorithm development, and demonstration testing in the single-nozzle test rig. A 30 percent reduction in the amplitude of the high-frequency (570 Hz) instability was achieved using actuation systems and control algorithms developed within this effort. Even larger reductions were shown with a low-frequency (270 Hz) instability. This represents a unique achievement in the development and practical demonstration of active combustion control systems for gas turbine applications.

  12. Slope stability and erosion control: Ecotechnological solutions

    NARCIS (Netherlands)

    Norris, J.E.; Stokes, A.; Mickovski, S.B.; Cammeraat, E.; van Beek, R.; Nicoll, B.C.; Achim, A.

    2008-01-01

    This book is designed to assist the civil and geotechnical engineer, geomorphologist, forester, landscape architect or ecologist in choosing ecotechnological solutions for slopes that are prone to a variety of mass movements e.g. shallow failure or erosion. Within this book, the 'engineer' is used i

  13. Slope stability and erosion control: Ecotechnological solutions

    NARCIS (Netherlands)

    Norris, J.E.; Stokes, A.; Mickovski, S.B.; Cammeraat, E.; van Beek, R.; Nicoll, B.C.; Achim, A.

    2008-01-01

    This book is designed to assist the civil and geotechnical engineer, geomorphologist, forester, landscape architect or ecologist in choosing ecotechnological solutions for slopes that are prone to a variety of mass movements e.g. shallow failure or erosion. Within this book, the 'engineer' is used

  14. Slope stability and erosion control: Ecotechnological solutions

    NARCIS (Netherlands)

    Norris, J.E.; Stokes, A.; Mickovski, S.B.; Cammeraat, E.; van Beek, R.; Nicoll, B.C.; Achim, A.

    2008-01-01

    This book is designed to assist the civil and geotechnical engineer, geomorphologist, forester, landscape architect or ecologist in choosing ecotechnological solutions for slopes that are prone to a variety of mass movements e.g. shallow failure or erosion. Within this book, the 'engineer' is used i

  15. Control of erosive tooth wear: possibilities and rationale

    Directory of Open Access Journals (Sweden)

    Mônica Campos Serra

    2009-06-01

    Full Text Available Dental erosion is a type of wear caused by non bacterial acids or chelation. There is evidence of a significant increase in the prevalence of dental wear in the deciduous and permanent teeth as a consequence of the frequent intake of acidic foods and drinks, or due to gastric acid which may reach the oral cavity following reflux or vomiting episodes. The presence of acids is a prerequisite for dental erosion, but the erosive wear is complex and depends on the interaction of biological, chemical and behavioral factors. Even though erosion may be defined or described as an isolated process, in clinical situations other wear phenomena are expected to occur concomitantly, such as abrasive wear (which occurs, e.g, due to tooth brushing or mastication. In order to control dental loss due to erosive wear it is crucial to take into account its multifactorial nature, which predisposes some individuals to the condition.

  16. Profitability of soil erosion control technologies in eastern Uganda ...

    African Journals Online (AJOL)

    Profitability of soil erosion control technologies in eastern Uganda Highlands. ... Log in or Register to get access to full text downloads. ... Abstract. The lack of farmer awareness of costs and benefits associated with the use of sustainable land ...

  17. Quantitative evaluation of strategies for erosion control on a railway embankment batter

    Science.gov (United States)

    Gyasi-Agyei, Y.; Sibley, J.; Ashwath, N.

    2001-12-01

    Strategies for erosion control on a railway embankment batter (side slope) are quantitatively evaluated in this paper. The strategies were centred on control (do nothing treatment), grass seeding, gypsum application, jute mat (an erosion control blanket) placement and planting hedgerows of Monto vetiver grass. Rainfall and runoff were monitored at 1 min intervals on 10 m wide embankment batter plots during 1998 and 1999. Total bedload and suspended sediment eroded from the plots were also measured but only for a group of storm events within sampling intervals. It has been demonstrated that vetiver grass is not cost-effective in controlling erosion on railway batters within Central Queensland region. Seeding alone could cause 60% reduction in the erosion rate compared with the control treatment. Applying gypsum to the calcium-deficient soil before seeding yielded an additional 25% reduction in the erosion rate. This is the result, primarily, of 100% grass cover establishment within seven months of sowing. Therefore, for railway embankment batter erosion control, the emphasis needs to be on rapid establishment of 100% grass cover. For rapid establishment of grass cover, irrigation is necessary during the initial stages of growth as the rainfall is unpredictable and the potential evaporation exceeds rainfall in the study region. The risk of seeds and fertilizers being washed out by short-duration and high-intensity rainfall events during the establishment phase may be reduced by the use of erosion control blankets on sections of the batters. Accidental burning of grasses on some plots caused serious erosion problems, resulting in very slow recovery of grass growth. It is therefore recommended that controlled burning of grasses on railway batters should be avoided to protect batters from being exposed to severe erosion.

  18. Climatic controls on the pace of glacier erosion

    Science.gov (United States)

    Koppes, Michele; Hallet, Bernard; Rignot, Eric; Mouginot, Jeremie; Wellner, Julia; Love, Katherine

    2016-04-01

    Mountain ranges worldwide have undergone large-scale modification due the erosive action of ice, yet the mechanisms that control the timing of this modification and the rate by which ice erodes remain poorly understood. Available data report a wide range of erosion rates from individual ice masses over varying timescales, suggesting that modern erosion rates exceed orogenic rates by 2-3 orders of magnitude. These modern rates are presumed to be due to dynamic acceleration of the ice masses during deglaciation and retreat. Recent numerical models have focused on replicating the processes that produce the geomorphic signatures of glacial landscapes. Central to these models is a simple quantitative index that relates erosion rate to ice dynamics and to climate. To provide such an index, we examined explicitly the factors controlling modern glacier erosion rates across climatic regimes. Holding tectonic history, bedrock lithology and glacier hypsometries relatively constant across a latitudinal transect from Patagonia to the Antarctic Peninsula, we find that modern, basin-averaged erosion rates vary by three orders of magnitude, from 1->10 mm yr-1 for temperate tidewater glaciers to 0.01-ELA, in accord with theory. The general relationship between ice dynamics and erosion suggests that the erosion rate scales non-linearly with basal sliding speed, with an exponent n ≈ 2-2.62. Notably, erosion rates decrease by over two orders of magnitude between temperate and polar glaciers with similar ice discharge rates. The difference in erosion rates between temperate and colder glaciers of similar shape and size is primarily related to the abundance of meltwater accessing the bed. Since all glaciers worldwide have experienced colder than current climatic conditions, the 100-fold decrease in long-term relative to modern erosion rates may in part reflect the temporal averaging of warm and cold-based conditions over the lifecycle of these glaciers. Higher temperatures and

  19. Use of palm-mat geotextiles for rainsplash erosion control

    Science.gov (United States)

    Bhattacharyya, R.; Fullen, M. A.; Davies, K.; Booth, C. A.

    2010-07-01

    Soil detachment by raindrop action (rainsplash erosion) is a very important subprocess of erosion by water. It is a particular problem in the UK as most soils are sandy or loamy sand in texture and lands have gentle to medium slope. However, few studies report potential rainsplash erosion control options under field conditions. Hence, the utilization of palm-mat geotextiles as a rainsplash erosion control technique was investigated at Hilton, east Shropshire, U.K. (52°33'5.7″ N, 2°19'18.3″ W). Geotextile-mats constructed from Borassus aethiopum (Borassus palm of West Africa) and Mauritia flexuosa (Buriti palm of South America) leaves are termed Borassus mats and Buriti mats, respectively. Two-year field experiments were conducted at Hilton to study the effects of emplacing Borassus and Buriti mats on rainsplash erosion of a loamy sand soil. Two sets (12 plots each) of experiments were established to study the effects of these mats on splash height and splash erosion. Splash height needs to be known to assess the transport mechanism of major soil fraction and its constituents on sloping land by rainsplash. In both sets, six randomly-selected plots were covered with mats, and the rest were bare. Results (during 22/01/2007‒23/01/2009; total precipitation = 1731.5 mm) show that Borassus mat-covered plots had ˜ 89% ( P 0.05) effect in rainsplash erosion control during that period, although plots with Buriti mats significantly ( P 0.05) improve selected soil properties (i.e., soil organic matter, particle size distribution, aggregate stability and total soil carbon) as soil organic matter (SOM) input from mat-decomposition was much less than total SOM content. However, the changes in fine and medium sand contents (after 2 years) in the Borassus covered plots were significantly ( P < 0.05; n = 6) related to the total rainsplash erosion during 2007‒2009. Emplacement of Borassus and Buriti mats on bare soils did not decrease SOM contents after 2 years, indicating

  20. The success of headwater rehabilitation towards gully erosion control

    Science.gov (United States)

    Frankl, Amaury; Poesen, Jean; Nyssen, Jan

    2017-04-01

    The ill-management of headwaters has frequently shown to have adverse effects on both humans and the environment. Historical examples often refer to altered hydrological conditions and stream incision resulting from deforestation. Agricultural expansion and intensification - often accompanied with land reforms in the 20th century - also showed to severely impact the fluvial environment, with stream incision and gully erosion hazards increasingly affecting many headwater areas around the world. To counter this, many regions have adopted improved management schemes aiming at restoring the physical, biological and hydrological integrity of the soil- and landscape. In terms of hydrogeomorpology, the objective was to minimize dynamics to a lower level so that runoff, sediment and pollutant transfers do not cause danger to human life, environmental/natural resources deterioration or economic stress. Therefore, much attention was given to the rehabilitation and re-naturalization of headwater streams and gullies, which are the conduits of these transfers. This is done in both indirect and direct ways, i.e. reducing the delivery of runoff and sediment to the gullies and interventions in the incised channels. Although much has been published on gully erosion development and control, few studies assess the success of gully rehabilitation on the mid- to long term or confront results against the gully life-cycle. The latter refers to the rate law in fluvial geomorphology, whereby gully morphological changes (increases in length, area, volume) are initially rapid, followed by a much slower development towards a new equilibrium state. Here, we present a review of headwater rehabilitation measures and their success towards gully erosion control. By confronting this to the life-cycle of a gully, we also want to shed light on our understanding of when and where gully erosion control needs to be applied; making land management more efficient and effective. Keywords: land

  1. Does control of soil erosion inhibit aquatic eutrophication?

    Science.gov (United States)

    Ekholm, Petri; Lehtoranta, Jouni

    2012-01-01

    Much of the phosphorus (P) from erosive soils is transported to water bodies together with eroded soil. Studies clarifying the impact of soil erosion on eutrophication have sought largely to quantify the reserves of P in soil particles that can be desorbed in different types of receiving waters. Aquatic microbiology has revealed that the cycling of P is coupled to the availability of common electron acceptors, Fe oxides and SO₄, through anaerobic mineralization in sediments. Eroded soil is also rich in Fe oxides, and their effect on the coupled cycling of C, Fe, S, and P has been neglected in eutrophication research. Soil erosion, and its control, should therefore be studied by considering not only the processes occurring in the water phase but also those taking place after the soil particles have settled to the bottom. We propose that in SO₄-rich systems, Fe oxides transported by eroded soil may promote Fe cycling, inhibit microbial SO₄ reduction and maintain the ability of sediment to retain P. We discuss the mechanisms through which eroded soil may affect benthic mineralization processes and the manner in which soil erosion may contribute to or counteract eutrophication.

  2. Morphopedologic approach for diagnosis and control of erosion

    Directory of Open Access Journals (Sweden)

    Thiago de Oliveira Faria

    2013-08-01

    Full Text Available This paper describes a morphopedological approach applied to the Sapo River sub-basin to support territorial management for soil and water conservation. The approach follows the conception of the morphopedological compartment presented by Salomão (1994, which considers terrain homogenous units based on soil, relief and geological substrate. Three thematic maps of 1:50,000 scale were made to characterize the morphopedology. Afterwards, spatial analyses techniques were developed in GIS to outline the morphopedological compartments considering the hydraulic functions of the relief inclination. As a result, 11 compartments of the physical environment with specific characteristics have been identified. Relatively smooth terrains predominated, formed by sandy soils in 76.41% of the studied area, represented by the MP-06 and MP-08 morphopedological compartments. These two units, together with the Quartzarenic Neosol, the MP-10 compartment with erosive amphitheaters of drainage head waters, the colluvial slopes and slope talus from the MP-07, and the median and low mountain sides of median hills of the MP-05 compartment, constitute the regions most vulnerable to erosion. Erosion occurs predominantly at the bottom of fluvial valleys from MP-05 and MP-06 and at drainage head waters, resulting in direct impacts on soil and waters of the basin due to silt build-up, hydromorphism losses and decrease of the water level. It was concluded that preventive actions are necessary to control erosion, especially in the most fragile areas.

  3. Estimating soil erosion risk and evaluating erosion control measures for soil conservation planning at Koga watershed in the highlands of Ethiopia

    Science.gov (United States)

    Molla, Tegegne; Sisheber, Biniam

    2017-01-01

    Soil erosion is one of the major factors affecting sustainability of agricultural production in Ethiopia. The objective of this paper is to estimate soil erosion using the universal soil loss equation (RUSLE) model and to evaluate soil conservation practices in a data-scarce watershed region. For this purpose, soil data, rainfall, erosion control practices, satellite images and topographic maps were collected to determine the RUSLE factors. In addition, measurements of randomly selected soil and water conservation structures were done at three sub-watersheds (Asanat, Debreyakob and Rim). This study was conducted in Koga watershed at upper part of the Blue Nile basin which is affected by high soil erosion rates. The area is characterized by undulating topography caused by intensive agricultural practices with poor soil conservation practices. The soil loss rates were determined and conservation strategies have been evaluated under different slope classes and land uses. The results showed that the watershed is affected by high soil erosion rates (on average 42 t ha-1 yr-1), greater than the maximum tolerable soil loss (18 t ha-1 yr-1). The highest soil loss (456 t ha-1 yr-1) estimated from the upper watershed occurred on cultivated lands of steep slopes. As a result, soil erosion is mainly aggravated by land-use conflicts and topographic factors and the rugged topographic land forms of the area. The study also demonstrated that the contribution of existing soil conservation structures to erosion control is very small due to incorrect design and poor management. About 35 % out of the existing structures can reduce soil loss significantly since they were constructed correctly. Most of the existing structures were demolished due to the sediment overload, vulnerability to livestock damage and intense rainfall. Therefore, appropriate and standardized soil and water conservation measures for different erosion-prone land uses and land forms need to be implemented in Koga

  4. Vegetative Erosion Control Studies Tennessee-Tombigbee Waterway.

    Science.gov (United States)

    1981-01-01

    available. All cultivars of rye were developed for rye grain production and its use for soil stabilization is secondary. Reseeding of rye will occur to a...FORESTRY EXPERIMENT STATION MISSISSIPPI STATE, MISSISSIPPI PRINCIPLE INVESTIGATOR JEFFREY V. KRANS RESEARCH ASSOCIATES CLIFFORD TRAMMEL RICHARD HARROD...with nitrogen fertilization. Its principle use in seeding mixtures for soil erosion control is for rapid establishment and persistant growth under

  5. Native plants for erosion control in urban river slopes

    Directory of Open Access Journals (Sweden)

    Virginia Alvarado

    2014-03-01

    Full Text Available Mechanical and structural erosion of soils is produced by the loss of the vegetal cover and the action of rain on unprotected surfaces. Raindrop impact, transport and sediment deposition leads to landslides and slope instability and soil loss. In Costa Rica, water bodies have been negatively impacted by urban development and both water resources and soils have become more vulnerable. This is the case of the Pirro river micro watershed where riverbed vegetation has been replaced by constructions producing erosion problems in its slopes. In order to evaluate how native plants favor sediment control and prevent this sediment from been deposited in the river, eight experimental plots were installed. Four treatments were established: A (Costus pulverulentus Presl, B (Heliconia tortuosa (Griggs Standl., C (Vetiveria zizanioides (L. Nash and D (control. Sediments were collected weekly during the rainy and transitional seasons. A clear relation between rainfall intensity and sediment production was determined, particularly for intensities higher than 50 mm h-1. Significant differences were also determined between the treatments and the efficiency order was B >A > C >D, with the native plants being the most efficient in terms of sediment control. The use of native plants is recommended for the management and rehabilitation of slopes near urban rivers due to their ecological value and their capability for sediment control.

  6. Global carbon export from the terrestrial biosphere controlled by erosion.

    Science.gov (United States)

    Galy, Valier; Peucker-Ehrenbrink, Bernhard; Eglinton, Timothy

    2015-05-14

    Riverine export of particulate organic carbon (POC) to the ocean affects the atmospheric carbon inventory over a broad range of timescales. On geological timescales, the balance between sequestration of POC from the terrestrial biosphere and oxidation of rock-derived (petrogenic) organic carbon sets the magnitude of the atmospheric carbon and oxygen reservoirs. Over shorter timescales, variations in the rate of exchange between carbon reservoirs, such as soils and marine sediments, also modulate atmospheric carbon dioxide levels. The respective fluxes of biospheric and petrogenic organic carbon are poorly constrained, however, and mechanisms controlling POC export have remained elusive, limiting our ability to predict POC fluxes quantitatively as a result of climatic or tectonic changes. Here we estimate biospheric and petrogenic POC fluxes for a suite of river systems representative of the natural variability in catchment properties. We show that export yields of both biospheric and petrogenic POC are positively related to the yield of suspended sediment, revealing that POC export is mostly controlled by physical erosion. Using a global compilation of gauged suspended sediment flux, we derive separate estimates of global biospheric and petrogenic POC fluxes of 157(+74)(-50) and 43(+61)(-25) megatonnes of carbon per year, respectively. We find that biospheric POC export is primarily controlled by the capacity of rivers to mobilize and transport POC, and is largely insensitive to the magnitude of terrestrial primary production. Globally, physical erosion rates affect the rate of biospheric POC burial in marine sediments more strongly than carbon sequestration through silicate weathering. We conclude that burial of biospheric POC in marine sediments becomes the dominant long-term atmospheric carbon dioxide sink under enhanced physical erosion.

  7. Use of gabions and vegetation in erosion-control works

    Directory of Open Access Journals (Sweden)

    Matić Vjačeslava

    2009-01-01

    Full Text Available Heavy winter and spring rainfall during the years 2005, -06, -07, and -08 brought about numerous torrential floods and landslides throughout the world and in Serbia. They endangered people, animals, settlements, fields, and roads. This reminded us of a readily available, cheap, and efficient material: stone in wire baskets of doubly galvanized wire of various sizes and forms - gabions - which are also long-lasting, flexible, and ecological. If made according to prescribed standards, they offer a permanent solution for many erosion-control problems. In addition, they can be used in urgent interventions to protect the lives of humans, animals, and plants and prevent of immense material losses. This paper calls attention to an unjustifiably neglected but important material, easily manipulated and with significant advantages compared to other structural materials, as well as to the possibility of its successful combination with vegetation, viz., willow (Salix sp. cuttings and grasses.

  8. Structural practices for controlling sediment transport from erosion

    Science.gov (United States)

    Gabriels, Donald; Verbist, Koen; Van de Linden, Bruno

    2013-04-01

    Erosion on agricultural fields in the hilly regions of Flanders, Belgium has been recognized as an important economical and ecological problem that requires effective control measures. This has led to the implementation of on-site and off-site measures such as reduced tillage and the installation of grass buffers trips, and dams made of vegetative materials. Dams made out of coir (coconut) and wood chips were evaluated on three different levels of complexity. Under laboratory conditions, one meter long dams were submitted to two different discharges and three sediment concentrations under two different slopes, to assess the sediment delivery ratios under variable conditions. At the field scale, discharge and sediment concentrations were monitored under natural rainfall conditions on six 3 m wide plots, of which three were equipped with coir dams, while the other three served as control plots. The same plots were also used for rainfall simulations, which allowed controlling sediment delivery boundary conditions more precisely. Results show a clear advantage of these dams to reduce discharge by minimum 49% under both field and laboratory conditions. Sediment delivery ratios (SDR) were very small under laboratory and field rainfall simulations (4-9% and 2% respectively), while larger SDRs were observed under natural conditions (43%), probably due to the small sediment concentrations (1-5 g l-1) observed and as such a larger influence of boundary effects. Also a clear enrichment of larger sand particles (+167%) could be observed behind the dams, showing a significant selective filtering effect.

  9. Ground test for vibration control demonstrator

    Science.gov (United States)

    Meyer, C.; Prodigue, J.; Broux, G.; Cantinaud, O.; Poussot-Vassal, C.

    2016-09-01

    In the objective of maximizing comfort in Falcon jets, Dassault Aviation is developing an innovative vibration control technology. Vibrations of the structure are measured at several locations and sent to a dedicated high performance vibration control computer. Control laws are implemented in this computer to analyse the vibrations in real time, and then elaborate orders sent to the existing control surfaces to counteract vibrations. After detailing the technology principles, this paper focuses on the vibration control ground demonstration that was performed by Dassault Aviation in May 2015 on Falcon 7X business jet. The goal of this test was to attenuate vibrations resulting from fixed forced excitation delivered by shakers. The ground test demonstrated the capability to implement an efficient closed-loop vibration control with a significant vibration level reduction and validated the vibration control law design methodology. This successful ground test was a prerequisite before the flight test demonstration that is now being prepared. This study has been partly supported by the JTI CleanSky SFWA-ITD.

  10. 48 CFR 436.574 - Control of erosion, sedimentation, and pollution.

    Science.gov (United States)

    2010-10-01

    ..., sedimentation, and pollution. 436.574 Section 436.574 Federal Acquisition Regulations System DEPARTMENT OF... 436.574 Control of erosion, sedimentation, and pollution. The contracting officer shall insert the clause at 452.236-74, Control of Erosion, Sedimentation and Pollution, if there is a need for applying...

  11. 48 CFR 452.236-74 - Control of Erosion, Sedimentation, and Pollution.

    Science.gov (United States)

    2010-10-01

    ..., Sedimentation, and Pollution. 452.236-74 Section 452.236-74 Federal Acquisition Regulations System DEPARTMENT OF....236-74 Control of Erosion, Sedimentation, and Pollution. As prescribed in 436.574, insert the following clause: Control of Erosion, Sedimentation, and Pollution (NOV 1996) (a) Operations shall be...

  12. Bedload transport controls bedrock erosion under sediment-starved conditions

    Science.gov (United States)

    Beer, A. R.; Turowski, J. M.

    2015-07-01

    Fluvial bedrock incision constrains the pace of mountainous landscape evolution. Bedrock erosion processes have been described with incision models that are widely applied in river-reach and catchment-scale studies. However, so far no linked field data set at the process scale had been published that permits the assessment of model plausibility and accuracy. Here, we evaluate the predictive power of various incision models using independent data on hydraulics, bedload transport and erosion recorded on an artificial bedrock slab installed in a steep bedrock stream section for a single bedload transport event. The influence of transported bedload on the erosion rate (the "tools effect") is shown to be dominant, while other sediment effects are of minor importance. Hence, a simple temporally distributed incision model, in which erosion rate is proportional to bedload transport rate, is proposed for transient local studies under detachment-limited conditions. This model can be site-calibrated with temporally lumped bedload and erosion data and its applicability can be assessed by visual inspection of the study site. For the event at hand, basic discharge-based models, such as derivatives of the stream power model family, are adequate to reproduce the overall trend of the observed erosion rate. This may be relevant for long-term studies of landscape evolution without specific interest in transient local behavior. However, it remains to be seen whether the same model calibration can reliably predict erosion in future events.

  13. Demonstration and Research Pest Control. Manual 91.

    Science.gov (United States)

    Missouri Univ., Columbia. Agricultural Experiment Station.

    This training manual provides information needed to meet the minimum EPA standards for certification as a commercial applicator of pesticides in the demonstration and research pest control category. The text discusses pesticide-organism interactions such as penetration, transport, accumulation, and biological magnification. Integrating pesticides…

  14. Cloud forest restoration for erosion control in a Kichwa community of the Ecuadorian central Andes Mountains

    Science.gov (United States)

    Backus, L.; Giordanengo, J.; Sacatoro, I.

    2013-12-01

    The Denver Professional Chapter of Engineers Without Borders (EWB) has begun conducting erosion control projects in the Kichwa communities of Malingua Pamba in the Andes Mountains south of Quito, Ecuador. In many high elevation areas in this region, erosion of volcanic soils on steep hillsides (i.e., teach these skills to adjacent villages.

  15. Remote control of an impact demonstration vehicle

    Science.gov (United States)

    Harney, P. F.; Craft, J. B., Jr.; Johnson, R. G.

    1985-01-01

    Uplink and downlink telemetry systems were installed in a Boeing 720 aircraft that was remotely flown from Rogers Dry Lake at Edwards Air Force Base and impacted into a designated crash site on the lake bed. The controlled impact demonstration (CID) program was a joint venture by the National Aeronautics and Space Administration (NASA) and the Federal Aviation Administration (FAA) to test passenger survivability using antimisting kerosene (AMK) to inhibit postcrash fires, improve passenger seats and restraints, and improve fire-retardent materials. The uplink telemetry system was used to remotely control the aircraft and activate onboard systems from takeoff until after impact. Aircraft systems for remote control, aircraft structural response, passenger seat and restraint systems, and anthropomorphic dummy responses were recorded and displayed by the downlink stems. The instrumentation uplink and downlink systems are described.

  16. Precise spatial control of cavitation erosion in a vessel phantom by using an ultrasonic standing wave.

    Science.gov (United States)

    Shi, Aiwei; Huang, Peixuan; Guo, Shifang; Zhao, Lu; Jia, Yingjie; Zong, Yujin; Wan, Mingxi

    2016-07-01

    In atherosclerotic inducement in animal models, the conventionally used balloon injury is invasive, produces excessive vessel injuries at unpredictable locations and is inconvenient in arterioles. Fortunately, cavitation erosion, which plays an important role in therapeutic ultrasound in blood vessels, has the potential to induce atherosclerosis noninvasively at predictable sites. In this study, precise spatial control of cavitation erosion for superficial lesions in a vessel phantom was realised by using an ultrasonic standing wave (USW) with the participation of cavitation nuclei and medium-intensity ultrasound pulses. The superficial vessel erosions were restricted between adjacent pressure nodes, which were 0.87 mm apart in the USW field of 1 MHz. The erosion positions could be shifted along the vessel by nodal modulation under a submillimetre-scale accuracy without moving the ultrasound transducers. Moreover, the cavitation erosion of the proximal or distal wall could be determined by the types of cavitation nuclei and their corresponding cavitation pulses, i.e., phase-change microbubbles with cavitation pulses of 5 MHz and SonoVue microbubbles with cavitation pulses of 1 MHz. Effects of acoustic parameters of the cavitation pulses on the cavitation erosions were investigated. The flow conditions in the experiments were considered and discussed. Compared to only using travelling waves, the proposed method in this paper improves the controllability of the cavitation erosion and reduces the erosion depth, providing a more suitable approach for vessel endothelial injury while avoiding haemorrhage.

  17. Control of erosion and water pollution during exploitation of the Meirama lignites. Control de la erosion y contaminacion de las aguas en la explotacion de lignitos de Meirama

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Jimeno, E. (Lignitos de Meirama, S.A. (Spain))

    1989-01-01

    The required reclamation of land disturbed by surface coal mining often results in the creation of some slopes and soils that are prone to rapid erosion and sediment production. The are two general methods of preventing or controlling soil erosion from rainfall and water running. These two methods are the building of mechanical structures and covering the soil with live vegetation. This paper discusses the water control methods, the design of the drainage and acid water treatment plant of Lignitos de Meirama. 5 refs., 10 figs.

  18. Control of water erosion and sediment in open cut coal mines in tropical areas

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, T.; Nugraha, C.; Matsui, K.; Shimada, H.; Ichinose, M.; Gottfried, J. [Kyushu University, Fukuoka (Japan). Department of Earth Resources Engineering

    2005-07-01

    The purpose is to reduce the environmental impacts from open cut mining in tropical areas, such as Indonesia and Vietnam. Research conducted on methods for the control of water erosion and sediment from open cut coal mines is described. Data were collected on climate and weathering in tropical areas, mechanism of water erosion and sedimentation, characteristics of rocks in coal measures under wet conditions, water management at pits and haul roads and ramps, and construction of waste dumps and water management. The results will be applied to the optimum control and management of erosion and sediments in open cut mining. 6 refs., 8 figs.

  19. Can anti-erosion dentifrices also provide effective plaque control?

    Science.gov (United States)

    Bellamy, P G; Prendergast, M; Strand, R; Yu, Z; Day, T N; Barker, M L; Mussett, A J

    2011-08-01

    While gingivitis and caries continue to be prevalent issues, there is growing concern about dental erosion induced by dietary acids. An oral hygiene product that protects against all these conditions would be beneficial. This study investigated the potential of two anti-erosion dentifrices to inhibit plaque. This was a randomized, three-period, two-treatment, double-blind, crossover study evaluating a stannous chloride/sodium fluoride dentifrice (SnCl(2)/NaF, blend-a-med(®) Pro Expert) and a popular anti-erosion dentifrice (NaF, Sensodyne(®) ProNamel(™)). During Period 3, subjects were randomized to repeat one treatment to evaluate any product carryover effects. Each treatment period was 17 days. Test dentifrices were used with a standard manual toothbrush. Digital plaque image analysis (DPIA) was employed at the end of each period to evaluate plaque levels (i) overnight (am prebrush); (ii) post-brushing with the test product (am post-brush); and (iii) mid-afternoon (pm). Analysis was conducted via an objective computer algorithm, which calculated total area of visible plaque. Twenty-seven subjects completed the study. At all time points, subjects had statistically significantly (P ≤ 0.0001) lower plaque levels after using the SnCl(2)/NaF dentifrice than the NaF dentifrice. The antiplaque benefit for the SnCl(2)/NaF dentifrice versus the NaF dentifrice was: am prebrush = 26.0%; am post-brushing = 27.9%; pm = 25.7%. The SnCl(2)/NaF dentifrice provided significantly greater daytime and overnight plaque inhibition than the NaF toothpaste. When recommending dentifrice to patients susceptible to dental erosion, clinicians can consider one that also inhibits plaque. © 2010 John Wiley & Sons A/S.

  20. Wind tunnel experimental study on the effect of PAM on soil wind erosion control.

    Science.gov (United States)

    He, Ji-Jun; Cai, Qiang-Guo; Tang, Ze-Jun

    2008-10-01

    In recent years, high-molecular-weight anionic polyacrylamide (PAM) have been widely tested on a variety of soils, primarily in water erosion control. However, little information is available regarding the effectiveness of PAM on preventing soil loss from wind erosion. The research adopted room wind tunnel experiment, two kinds of soils were used which were from the agro-pastoral area of Inner Mongolia, the northwest of China, the clay content of soils were 22.0 and 13.7%, respectively. For these tests, all the treatments were performed under the condition of wind velocity of 14 m s(-1) and a blown angle of 8.75%, according to the actual situation of experimented area. The study results indicated that using PAM on the soil surface could enhance the capability of avoiding the wind erosion, at the same time, the effect of controlling wind soil erosion with 4 g m(-2) PAM was better than 2 g m(-2) PAM's. Economically, the 2 g m(-2) PAM used in soil surface can control wind erosion effectively in this region. The prophase PAM accumulated in soil could not improve the capability of avoiding the wind erosion, owing to the degradation of PAM in the soil and the continual tillage year after year. The texture of soil is a main factor influencing the capability of soil avoiding wind erosion. Soil with higher clay content has the higher capability of preventing soil from wind erosion than one with the opposite one under the together action of PAM and water.

  1. Alternatives for erosion control by using conventional coverage, non-conventional coverage and revegetation

    Directory of Open Access Journals (Sweden)

    Claudia Díaz Mendoza

    2011-08-01

    Full Text Available Humankind’s unsustainable behaviour regarding landuse has negative effects on the environment, leading to loss of fertility and degradation and desertification; this has a direct impact on the decline and deterioration of water resources, soil erosion and thus changes in the weather leading to drier conditions. The foregoing are caused by the misuse of soil2. The way soil resources have suffered gradual deterioration has become evident in Colombia during recent years; this has been produced by erosion and the removal of mass caused by various factors including physical and chemical erosion. All the above, together with negative events such as global climate change and the sedimentation of rivers, means a negative environmental impact . Soil erosion and desertification are major environmental issues regarding disturbances and threats affecting the arid, semiarid and dry sub-humid Mediterranean region’s geo-ecosystems in the third millennium; additionally, economic global change may exacerbate such problems (Ingram et al., 1996; Williams et al., 1996. Regarding soil deterioration, soil vegetation cover and erosion control and mitigation measures should be introduced by using mechanisms which should be as natural as possible and do not induce fresh impacts on the environment. This literature review has thus documented the state of the art regarding several alternatives for erosion control currently involving bioengineering.

  2. Large-scale performance and design for construction activity erosion control best management practices.

    Science.gov (United States)

    Faucette, L B; Scholl, B; Beighley, R E; Governo, J

    2009-01-01

    The National Pollutant Discharge Elimination System (NPDES) Phase II requires construction activities to have erosion and sediment control best management practices (BMPs) designed and installed for site storm water management. Although BMPs are specified on storm water pollution prevention plans (SWPPPs) as part of the construction general permit (GP), there is little evidence in the research literature as to how BMPs perform or should be designed. The objectives of this study were to: (i) comparatively evaluate the performance of common construction activity erosion control BMPs under a standardized test method, (ii) evaluate the performance of compost erosion control blanket thickness, (iii) evaluate the performance of compost erosion control blankets (CECBs) on a variety of slope angles, and (iv) determine Universal Soil Loss Equation (USLE) cover management factors (C factors) for these BMPs to assist site designers and engineers. Twenty-three erosion control BMPs were evaluated using American Society of Testing and Materials (ASTM) D-6459, standard test method for determination of ECB performance in protecting hill slopes from rainfall induced erosion, on 4:1 (H:V), 3:1, and 2:1 slopes. Soil loss reduction for treatments exposed to 5 cm of rainfall on a 2:1 slope ranged from-7 to 99%. For rainfall exposure of 10 cm, treatment soil loss reduction ranged from 8 to 99%. The 2.5 and 5 cm CECBs significantly reduced erosion on slopes up to 2:1, while CECBs or= 4:1 when rainfall totals reach 5 cm. Based on the soil loss results, USLE C factors ranged from 0.01 to 0.9. These performance and design criteria should aid site planners and designers in decision-making processes.

  3. Training for Certification: Demonstration & Research Pest Control.

    Science.gov (United States)

    Mississippi State Univ., State College. Cooperative Extension Service.

    This Cooperative Extension Service publication from Mississippi State University is a training guide for commercial pesticide applicators. Focusing on agricultural pest control, this publication includes a full range of topics from uses of pesticides for agricultural animal pest control to the toxicity of common pesticides to fish and bees.…

  4. Climatic controls on steady state erosion using the relationship between channel steepness and cosmogenic 10Be-derived catchment averaged erosion rates

    Science.gov (United States)

    Rossi, M. W.; Whipple, K. X.; DiBiase, R. A.; Heimsath, A. M.

    2011-12-01

    To understand landscape response to climate change, baseline controls on erosion rates must be established for given climate conditions. Theory suggests a number of climate metrics should be important to erosion (i.e. precipitation, temperature, storminess, seasonality, snow fraction). Nevertheless, definitive field evidence quantifying how climate affects erosion rate has proven difficult to obtain. This is at least partly due to the difficulty of isolating climatic influences on erosion rates from topographic and rock strength influences. We circumvent this problem by evaluating how climate influences the relationship between erosion rate and topography in settings with similar rock types. At steady state, tectonic uplift dictates erosion rate, and climate and rock strength are manifest as changes in erosional efficiency - the topographic relief necessary to maintain the tectonically imposed erosion rate. In fluvial landscapes, bedrock rivers set the relevant scale of topographic relief, which can be described by the channel steepness index. A number of recent studies have shown that the relationship between channel steepness and millennial scale erosion rates is non-linear, implying that erosional efficiency increases with relief. Work in the San Gabriel Mountains suggests this relationship is due to erosion thresholds that limit incision of channels in low relief landscapes. By using a fluvial incision model that incorporates a range of daily discharge events coupled with an erosion threshold (Lague et al., 2005), the influence of flood frequency on the relationship between channel steepness and erosion rate can be explored. We apply this same modeling approach to five other landscapes that exhibit a range of channel steepness, have similar rock types (granitoids), but that are in dramatically different climate regimes ranging from desert to rainforest (annual rainfall, P, from 0.25 to 3 m/yr). Specifically, we present new cosmogenic 10Be erosion rate data from

  5. Effectiveness of the GAEC standard of cross compliance Management of set aside on soil erosion control

    Directory of Open Access Journals (Sweden)

    Paolo Bazzoffi

    2011-08-01

    Full Text Available The GAEC standard Management of set aside is applied to arable lands subjected to set aside and kept non-cultivated throughout the year. The standard is also applied to other set aside areas eligible for direct payments. For the implementation of this Standard, the farmer must assure the presence of natural or artificial green cover on the surface throughout the year and adopt consistent agronomic practices as mowing, or other equivalent, in order to maintain the normal state of soil fertility, protect wildlife, prevent the formation of a potential inoculum of fires, especially during drought and prevent the spread of weeds. Up to the CAP Health Check the legislation on the set aside required the farmer to plough the soil by mid-May. Therefore, the natural vegetation cover could neither establish nor express its value against erosion throughout the year. Since mid 2004, cross compliance has banned ploughing of set aside surfaces. This novelty is very important in relation to the effectiveness of the standard in erosion control. In Italy there are only few studies carried out in the field that have measured the effect of set aside on soil erosion. The few existing experiments regarded the effect of set aside managed in accordance with the CAP dictates prior to the CAP Health Check. The results of case studies show very contrasting results regarding soil erosion on set aside plots managed through the annual ploughing in the period in which this rule remained in force. This finding can be explained by considering that most of soil erosion in the Mediterranean environment is determined by extreme events; so, set aside resulted ineffective in protecting the soil, when very erosive events occurred on bare soil (soil in seed bed condition after ploughing and harrowing or when the plant cover of soil was still scarce. In these conditions soil erosion rate resulted similar to that observed in the intensive cropping systems. On the contrary, for events

  6. Biocompatible photocrosslinked poly(ester anhydride) based on functionalized poly(epsilon-caprolactone) prepolymer shows surface erosion controlled drug release in vitro and in vivo.

    Science.gov (United States)

    Mönkäre, J; Hakala, R A; Vlasova, M A; Huotari, A; Kilpeläinen, M; Kiviniemi, A; Meretoja, V; Herzig, K H; Korhonen, H; Seppälä, J V; Järvinen, K

    2010-09-15

    Star-shaped poly(epsilon-caprolactone) oligomers functionalized with succinic anhydride were used as prepolymers to prepare photocrosslinked poly(ester anhydride) to evaluate their in vivo drug delivery functionality and biocompatibility. Thus, in this work, erosion, drug release and safety of the photocrosslinked poly(ester anhydride) were examined in vitro and in vivo. A small water-soluble drug, propranolol HCl (M(w) 296 g/mol, solubility 50 mg/ml), was used as the model drug in an evaluation of the erosion controlled release. Drug-free and drug-loaded (10-60% w/w) poly(ester anhydride) discoids eroded in vitro (pH 7.4 buffer, +37 degrees C) linearly within 24-48 h. A strong correlation between the polymer erosion and the linear drug release in vitro was observed, indicating that the release had been controlled by the erosion of the polymer. Similarly, in vivo studies (s.c. implantation of discoids in rats) indicated that surface erosion controlled drug release from the discoids (drug loading 40% w/w). Oligomers did not decrease cell viability in vitro and the implanted discoids (s.c., rats) did not evoke any cytokine activity in vivo. In summary, surface erosion controlled drug release and the safety of photocrosslinked poly(ester anhydride) were demonstrated in this study.

  7. Model based optimization of wind erosion control by tree shelterbelt for suitable land management

    Science.gov (United States)

    Bartus, M.; Farsang, A.; Szatmári, J.; Barta, K.

    2012-04-01

    The degradation of soil by wind erosion causes huge problem in many parts of the world. The wind erodes the upper, nutrition rich part of the soil, therefore erosion causes soil productivity loss. The length of tree shelterbelts was significantly reduced by the collectivisation (1960-1989) and the wind erosion affected areas expanded in Hungary. The tree shelterbelt is more than just a tool of wind erosion control; by good planning it can increase the yield. The tree shelterbelt reduces the wind speed and changes the microclimate providing better condition to plant growth. The aim of our work is to estimate wind erosion risk and to find the way to reduce it by tree shelterbelts. A GIS based model was created to calculate the risk and the optimal windbreak position was defined to reduce the wind erosion risk to the minimum. The model is based on the DIN 19706 (Ermitlung der Erosiongefährdung von Böden durch Wind, Estimation of Wind Erosion Risk) German standard. The model uses five input data: structure and carbon content of soil, average yearly wind speed at 10 meters height, the cultivated plants and the height and position of windbreak. The study field (16km2) was chosen near Szeged (SE Hungary). In our investigation, the cultivated plant species and the position and height of windbreaks were modified. Different scenarios were made using the data of the land management in the last few years. The best case scenario (zero wind erosion) and the worst case scenario (with no tree shelter belt and the worst land use) were made to find the optimal windbreak position. Finally, the research proved that the tree shelterbelts can provide proper protection against wind erosion, but for optimal land management the cultivated plant types should also controlled. As a result of the research, a land management plan was defined to reduce the wind erosion risk on the study field, which contains the positions of new tree shelterbelts planting and the optimal cultivation.

  8. Real-time monitoring of controllable cavitation erosion in a vessel phantom with passive acoustic mapping.

    Science.gov (United States)

    Lu, Shukuan; Shi, Aiwei; Jing, Bowen; Du, Xuan; Wan, Mingxi

    2017-11-01

    Cavitation erosion in blood vessel plays an important role in ultrasound thrombolysis, drug delivery, and other clinical applications. The controllable superficial vessel erosion based on ultrasonic standing wave (USW) has been used to effectively prevent vessel ruptures and haemorrhages, and optical method is used to observe the experiments. But optical method can only work in transparent media. Compared with standard B-mode imaging, passive acoustic mapping (PAM) can monitor erosion in real time and has better sensitivity of cavitation detection. However, the conventionally used PAM has limitations in imaging resolution and artifacts. In this study, a unique PAM method that combined the robust Capon beamformer (RCB) with the sign coherence factor (SCF) was proposed to monitor the superficial vessel erosion in real time. The performance of the proposed method was validated by simulations. In vitro experiments showed that the lateral (axial) resolution of the proposed PAM was 2.31±0.51 (3.19±0.38) times higher than time exposure acoustics (TEA)-based PAM and 1.73±0.38 (1.76±0.48) times higher than RCB-based PAM, and the cavitation-to-artifact ratio (CAR) of the proposed PAM could be improved by 22.5±3.2dB and 7.1±1.2dB compared with TEA and RCB-based PAM. These results showed that the proposed PAM can precisely monitor the superficial vessel erosion and the erosion shift after USW modulation. This work may have the potential of developing a useful tool for precise spatial control and real-time monitoring of the superficial vessel erosion. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. The implementing of some plant species in erosion control on slopes

    Directory of Open Access Journals (Sweden)

    Matić Vjačeslava

    2010-01-01

    Full Text Available With the need to conserve and improve the environment, it is recommended to employ plant materials in the erosion control of torrents and slopes alongside roads. Considering the well-known properties of some willow species regarding their power of vegetative reproduction, survival in poor soils and often flooded alluvium, we researched into the potentials of the following species: Salix triandra L., Salix purpurea L. and Salix incana Schrk. in the catchment of the warehouse 'Gvozdac', Experimental Estate Goč, Serbia. The research started in 2004 and has continued till the present day. The above-mentioned willow species showed significant efficiency in the bank protection of torrential watercourses and on the moist slopes of embankments and cuts of roads. Some of them can even stand a certain degree of aridity, while other species, on poor, eroded soil exposed to long and extreme drought, could not survive and did not show the expected effect, which is also the consequence of the absence of maintenance and adequate attention to such erosion-control works. In spite of the above, one of the willow species survived even in the most severe conditions, checking the erosion of the road cut slope and the road construction itself, and prevented the impacts of aggressive atmospheric waters, thus halting the erosion ridges and the removal of the asphalt road surface. The above facts prove that, with adequate measures of maintenance, plant materials can be very successfully applied for both longitudinal structures and to check dams in torrent control, as well as in erosion control on the slopes in catchments, both in civil engineering works and in forest exploitation. The research requires closer attention, extending the interests to some grass and shrub species, with the aim of ecological erosion control and reclamation of endangered watercourses, slopes and, in general, environmental protection and nature conservation. .

  10. Controlled Hydrogen Fleet and Infrastructure Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Scott Staley

    2010-03-31

    This program was undertaken in response to the US Department of Energy Solicitation DE-PS30-03GO93010, resulting in this Cooperative Agreement with the Ford Motor Company and BP to demonstrate and evaluate hydrogen fuel cell vehicles and required fueling infrastructure. Ford initially placed 18 hydrogen fuel cell vehicles (FCV) in three geographic regions of the US (Sacramento, CA; Orlando, FL; and southeast Michigan). Subsequently, 8 advanced technology vehicles were developed and evaluated by the Ford engineering team in Michigan. BP is Ford's principal partner and co-applicant on this project and provided the hydrogen infrastructure to support the fuel cell vehicles. BP ultimately provided three new fueling stations. The Ford-BP program consists of two overlapping phases. The deliverables of this project, combined with those of other industry consortia, are to be used to provide critical input to hydrogen economy commercialization decisions by 2015. The program's goal is to support industry efforts of the US President's Hydrogen Fuel Initiative in developing a path to a hydrogen economy. This program was designed to seek complete systems solutions to address hydrogen infrastructure and vehicle development, and possible synergies between hydrogen fuel electricity generation and transportation applications. This project, in support of that national goal, was designed to gain real world experience with Hydrogen powered Fuel Cell Vehicles (H2FCV) 'on the road' used in everyday activities, and further, to begin the development of the required supporting H2 infrastructure. Implementation of a new hydrogen vehicle technology is, as expected, complex because of the need for parallel introduction of a viable, available fuel delivery system and sufficient numbers of vehicles to buy fuel to justify expansion of the fueling infrastructure. Viability of the fuel structure means widespread, affordable hydrogen which can return a reasonable profit to

  11. Er:YAG laser irradiation to control the progression of enamel erosion: an in situ study.

    Science.gov (United States)

    Scatolin, R S; Colucci, V; Lepri, T P; Alexandria, A K; Maia, L C; Galo, R; Borsatto, M C; Corona, S A M

    2015-07-01

    This in situ study evaluated the effect of Er:YAG laser irradiation in controlling the progression of enamel erosion-like lesions. Fifty-six enamel slabs (330 KHN ± 10 %) with one fourth of the surface covered with resin composite (control area) were submitted to initial erosion-like lesion formation with citric acid. The slabs were divided into two groups: irradiated with Er:YAG laser and non-irradiated. Fourteen volunteers used an intraoral palatal appliance containing two slabs, in two phases of 5 days each. During the intraoral phase, in a crossed-over design, half of the volunteers immersed the appliance in citric acid while the other half used deionized water, both for 5 min, three times per day. Enamel wear was determined by an optical 3D profilometer. ANOVA revealed that when deionized water was used as immersion solution during the intraoral phase, lower values of wear were showed when compared with the groups that were eroded with citric acid, whether irradiated or non-irradiated with Er:YAG laser. When erosion with citric acid was performed, Er:YAG laser was not able to reduce enamel wear. Small changes on enamel surface were observed when it was irradiated with Er:YAG laser. It may be concluded that Er:YAG laser irradiation did not reduce the progression of erosive lesions on enamel submitted to in situ erosion with citric acid.

  12. Fractal Erosion of the Safe Basin in a Helmholtz Oscillator and Its Control by Linear Delayed Velocity Feedback

    Institute of Scientific and Technical Information of China (English)

    SHANG Hui-Lin; WEN Yong-Peng

    2011-01-01

    Fractal erosion of the safe basin in a Helmholtz oscillator system is studied. A linear delayed velocity feedback is employed to suppress the fractal erosion. The necessary basin erosion condition of the delayed feedback controlled system is obtained. The evolution of the boundary and area of the safe basin over time delay is also presented. It follows that the delayed velocity feedback can be used as an effective strategy to control fractal erosion of a safe basin.%Fractal erosion of the safe basin in a Helmholtz oscillator system is studied.A linear delayed velocity feedback is employed to suppress the fractal erosion.The necessary basin erosion condition of the delayed feedback controlled system is obtained.The evolution of the boundary and area of the safe basin over time delay is also presented.It follows that the delayed velocity feedback can be used as an effective strategy to control fractal erosion of a safe basin.Since the safe basin was induced to explain the integrity of dynamical systems,studies on safe basins have attracted much attention.[1-6] Leigh and Armin calculated the survival probability of a ferry in random seas by estimating the erosion of the safe basin during the ship rolling motion by using Monte Carlo simulations.[1] Lenci and Rega induced the erosion of a safe basin to explain pull-in phenomenon in micro-electro mechanical systems.[2

  13. Erosion control and protection from torrential floods in Serbia-spatial aspects

    Directory of Open Access Journals (Sweden)

    Ristić Ratko

    2011-01-01

    Full Text Available Torrential floods represent the most frequent phenomenon within the category of “natural risks” in Serbia. The representative examples are the torrential floods on the experimental watersheds of the rivers Manastirica (June 1996 and Kamišna (May 2007. Hystorical maximal discharges (Qmaxh were reconstructed by use of ″hydraulics flood traces″ method. Computations of maximal discharges (Qmaxc, under hydrological conditions after the restoration of the watersheds, were performed by use of a synthetic unit hydrograph theory and Soil Conservation Service methodology. Area sediment yields and intensity of erosion processes were estimated on the basis of the “Erosion Potential Method”. The actual state of erosion processes is represented by the coefficients of erosion Z=0.475 (Manastirica and Z=0.470 (Kamišna. Restoration works have been planned with a view to decreasing yields of erosive material, increasing water infiltration capacity and reducing flood runoff. The planned state of erosion processes is represented by the coefficients of erosion Z=0.343 (Manastirica and Z=0.385 (Kamišna. The effects of hydrological changes were estimated by the comparison of historical maximal discharges and computed maximal discharges (under the conditions after the planned restoration. The realisation of restoration works will help decrease annual yields of erosive material from Wа=24357 m3 to Wа=16198.0 m3 (Manastirica and from Wа=19974 m3 to Wа=14434 m3 (Kamišna. The values of historical maximal discharges (QmaxhMan=154.9 m3•s-1; QmaxhKam=76.3 m3•s-1 were significantly decreased after the restoration (QmaxcMan=84.5 m3 •s-1; QmaxcKam=43.7 m3•s-1, indicating the improvement of hydrological conditions, as a direct consequence of erosion and torrent control works. Integrated management involves biotechnical works on the watershed, technical works on the hydrographic network within a precisely defined administrative and spatial framework in

  14. Erosion control on a steeply sloped pipeline right-of-way in southwestern Pennsylvania

    Energy Technology Data Exchange (ETDEWEB)

    Zellmer, S.D.; Edgar, D.E. (Argonne National Lab., IL (USA)); Isaacson, H.R. (Gas Research Inst., Chicago, IL (USA))

    1991-01-01

    The results of precipitation on steeply sloped pipeline rights-of-way (ROWs) during the time between ROW rehabilitation and the establishment of a dense, self-sustaining vegetative ground cover can cause locally severe soil erosion. This erosion results in elevated sediment loads in receiving streams and increases the difficulty and costs of ROW maintenance. A field study was completed that compared the environmental effectiveness of nine treatments on a 28% ROW slope in southwestern Pennsylvania. The six erosion-control methods investigated in the study, selected to represent a wide range in material type and installation cost, were (1) heavy application of straw mulch, (2) light application of straw mulch, (3) processed wood fiber, (4) chemical soil binder, (5) paper strips in netting, and (6) light straw mulch with a tacking agent. Each of the test plots also received the basic treatment of limestone, fertilizer, and a seed mixture commonly used to rehabilitate ROWs in the region. Precipitation, runoff volumes, and sediment yields were measured on each of 51 plots for 45 precipitation events during the 18-month study. Vegetation data were collected by the point-intercept method four times during the study to determine the amount of plant cover and species composition. Differences in sediment yield were observed among methods and between ROW location, but plant cover development was not influenced by erosion-control method or location. The relationship between environmental and cost data indicated that, of the six erosion-control methods tested, a light application of straw mulch was the most effective erosion-control treatment. 19 refs., 2 figs., 6 tabs.

  15. Effectiveness of the GAEC cross-compliance standard Short-term measures for runoff water control on sloping land (temporary ditches and grass strips in controlling soil erosion

    Directory of Open Access Journals (Sweden)

    Paolo Bazzoffi

    2011-08-01

    Full Text Available The agronomic measures made obligatory by the cross-compliance Standard Temporary measures for runoff water control on sloping land included in the Ministry of Agricultural, Food and Forestry Policies (MiPAAF decree on cross compliance until 2008, and by Standard 1.1 Creation of temporary ditches for the prevention of soil erosion in the 2009 decree, certainly appear to be useful for the control of soil erosion and runoff. The efficacy of temporary drainage ditches and of grass strips in controlling runoff and erosion has been demonstrated in trials conducted in field test plots in Italy. When level temporary drainage ditches are correctly built, namely with an inclination of not more than 2.5% in relation to the maximum hillslope gradient, they allow the suspended sediment eroded upstream to settle in the ditches, retaining the material carried away on the slope and, as a result, reducing the quantity of sediment delivered to the hydrographic network. In particular, among all the results, the erosion and runoff data in a trial conducted in Guiglia (Modena showed that in corn plots, temporary drainage ditches reduced soil erosion by 94%, from 14.4 Mg ha-1 year-1 (above the limit established by the NRCS-USDA of 11.2 Mg ha-1 year-1 to 0.8 Mg ha-1 year-1 (within the NRCS limit and also within the more restrictive limit established by the OECD of 6.0 Mg ha-1 year-1. With respect to the grass buffer strips the most significant research was carried out in Volterra. This research demonstrated their efficacy in reducing erosion from 8.15 Mg ha-1 to 1.6 Mg ha-1, which is approximately 5 times less than the erosion observed on bare soil. The effectiveness of temporary drainage ditches was also assessed through the application of the Revised Universal Soil Loss Equation (RUSLE erosion model to 60 areas under the control of the Agency for Agricultural Payments (AGEA in 2009, comparing the risk of erosion in these sample areas by simulating the presence and

  16. Control of high-Z PFC erosion by local gas injection in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Rudakov, D.L., E-mail: rudakov@fusion.gat.com [University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0417 (United States); Stangeby, P.C. [University of Toronto Institute for Aerospace Studies, Toronto M3H 5T6 (Canada); Wong, C.P.C. [General Atomics, P. O. Box 85608, San Diego, CA 92186-5608 (United States); McLean, A.G. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Wampler, W.R. [Sandia National Laboratory, P.O. Box 5800, Albuquerque, NM 87185 (United States); Watkins, J.G. [Sandia National Laboratory, P.O. Box 969, Livermore, CA 94551-0969 (United States); Boedo, J.A. [University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0417 (United States); Briesemeister, A. [Oak Ridge National Laboratory, Oak Ridge, TN 37830 (United States); Buchenauer, D.A. [Sandia National Laboratory, P.O. Box 969, Livermore, CA 94551-0969 (United States); Chrobak, C.P. [General Atomics, P. O. Box 85608, San Diego, CA 92186-5608 (United States); Elder, J.D. [University of Toronto Institute for Aerospace Studies, Toronto M3H 5T6 (Canada); Fenstermacher, M.E. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Guo, H.Y. [General Atomics, P. O. Box 85608, San Diego, CA 92186-5608 (United States); Lasnier, C.J. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Leonard, A.W. [General Atomics, P. O. Box 85608, San Diego, CA 92186-5608 (United States); Maingi, R. [Princeton Plasma Physics Laboratory, PO Box 451, Princeton, NJ 08543 (United States); Moyer, R.A. [University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0417 (United States)

    2015-08-15

    Reduced erosion of a high-Z PFC divertor surface was observed in DIII-D with local injection of methane and deuterium gases. Molybdenum-coated silicon samples were exposed in the lower divertor of DIII-D using DiMES under plasma conditions previously shown to cause significant net erosion of Mo. Three exposures with {sup 13}CH{sub 4} and one exposure with D{sub 2} gas injection about 12 cm upstream of the samples located within 1–2 cm of the attached strike point were performed. Reduction of Mo erosion was evidenced in-situ by the suppression of MoI line radiation at 386.4 nm once the gas injection started. Post-mortem ion beam analysis demonstrated that the net erosion of molybdenum near the center of the samples exposed with {sup 13}CH{sub 4} injection was below the measurement resolution of 0.5 nm, corresponding to a rate of ⩽0.04 nm/s. Compared to the previously measured erosion rates, this constitutes a reduction by a factor of >10.

  17. Sediment storage dam: A structural gully erosion control and sediment trapping measure, northern Ethiopia

    Science.gov (United States)

    Mekonnen, Mulatie; Keesstra, Saskia; Baartman, Jantiene; Ritsema, Coen

    2014-05-01

    Gully erosion is a prime problem in Ethiopia. This study assessed the severity of gully erosion and the role of sediment storage dams (SSD) in restoring gullies and preventing further gully development, its sediment trapping efficacy (STE) and its capacity in converting degraded gully lands to productive land. On average 2.5 m deep, 6.6 m wide and 28.3 m long gullies were formed in Minizr watershed, northwest Ethiopia, in 2013. Concentrated surface runoff, traditional ditches, graded terraces without suitable water ways and road construction are the main causes of such serious gully erosion. Over grazing, tunnel flow and lack of proper immediate gully treatment actions after gully initiation are found to be additional causes of the problem. Gully erosion was also found as the major source of sediment for downstream rivers and water reservoirs. The annual volume of soil eroded from only four gullies was 1941.3 m3. To control gully erosion, SSDs were found to be important physical structures, which can trap significant amount of sediment within gullies and they can convert unproductive gully land to productive agricultural land for fruit and crop production. Eight SSDs trapped about 44*103 m3 of sediment within 2 to 8 years. Two representative SSDs constructed using gabion and stone were tested for their STE. Results showed that their efficacy was 74.1% and 66.4% for the gabion and stone SSDs, respectively. Six of the older SSDs were already full of sediment and created 0.75 ha of productive land within 2 to 8 years. SSDs best fits to treat large size and deep gullies where other gully control measures, check dams, could not function well. To prevent gully formation, controlling its causes that is avoiding traditional ditches, practicing grassed water ways to safely remove runoff water from graded terraces, integrated watershed and road side management practices are important solutions. KEY WORDS: Sediment storage dam, gully erosion, sediment trapping efficacy

  18. Processes and controls of ditch erosion and suspended sediment transport in drained peatland forests

    Science.gov (United States)

    Tuukkanen, Tapio; Stenberg, Leena; Marttila, Hannu; Finér, Leena; Piirainen, Sirpa; Koivusalo, Harri; Kløve, Bjørn

    2016-04-01

    Drainage and periodic ditch cleaning are needed in peatland forests to allow adequate tree growth. The downside is that these practices usually increase erosion and transport of organic and inorganic matter to downstream waterbodies. In this study, our aim was to assess the role of hydrological factors and ditch-level bed and bank erosion processes in controlling suspended sediment (SS) transport in peatland forests after ditch cleaning. To do this, a 113 ha catchment and a nested sub-catchment (5.2 ha) in eastern Finland were instrumented for continuous hydrological and SS concentration (turbidity) measurements and for the detection of ditch bed and bank erosion with erosion pins. The impacts of ditch cleaning on instantaneous unit hydrographs were also assessed against two reference catchments. The results suggested that, in small intensively drained catchments, SS transport is likely to be limited by the availability of easily erodible sediment in the ditch network, and that ditch cleaning operations as well as preparatory bank erosion processes such as peat desiccation and frost action can be important in producing erodible sediment for transport. Detachment of soil particle from ditch banks by raindrop impact can also be an important factor explaining variations in SS concentrations in small catchments. In larger drainage areas, peak runoff characteristics may play a more dominant role in SS transport. The results give new insights into the dynamics of sediment transport in drained peatland catchments, which can be useful, for example, for planning and implementation of water conservation measures.

  19. Folly Beach, South Carolina. Survey Report on Beach Erosion Control and Hurricane Protection. Appendixes.

    Science.gov (United States)

    1979-08-01

    IF QRC u R E S ~RE FAGEPAIF’D Imt ErEXISTING Sos’,REACH EROSION So, CONTROL STRUCTURES 0r~ 2 JIMMM MII~ FOLLY REACH SOUTH CAROLINA FIGURE C-7 best...adult stages of some invertebrate species such as jellyfish. 2.23 The nekton group consists of animals which are strong swimmers . Fish are the principal

  20. Using computer models to design gully erosion control structures for humid northern Ethiopia

    Science.gov (United States)

    Classic gully erosion control measures such as check dams have been unsuccessful in halting gully formation and growth in the humid northern Ethiopian highlands. Gullies are typically formed in vertisols and flow often bypasses the check dams as elevated groundwater tables make gully banks unstable....

  1. Contour hedgerows and grass strips in erosion and runoff control in semi-arid Kenya

    NARCIS (Netherlands)

    Kinama, J.M.; Stigter, C.J.; Ong, C.K.; Ng'ang'a, J.K.; Gichuki, F.N.

    2007-01-01

    Most early alley cropping studies in semi-arid Kenya were on fairly flat land while there is an increase in cultivated sloping land. The effectiveness of aging contour hedgerows and grass strips for erosion control on an about 15% slope of an Alfisol was compared. The five treatments were Senna

  2. Critical evaluation of compost erosion control blankets (CECBs) against conventional best management practices (BMPs) for the prevention and control of soil erosion, nutrient loss and storm water runoff from engineered slopes under simulated UK conditions

    OpenAIRE

    Mantovani, Dario

    2010-01-01

    In recent decades increasing attention has been dedicated to issues of sustainable land management. Soil is essential for a number of functions and services which are central to the sustainability of agro-ecosystems and the global economy. Consequently soil management and specifically soil erosion including, erosion from construction activities, is moving up the political and legislative agenda. This thesis investigated the suitability of Compost Erosion Control Blankets (CE...

  3. Integrated erosion control measures and environmental effects in rocky mountainous areas in northern China

    Institute of Scientific and Technical Information of China (English)

    HE Jijun; CAI Qiangguo; LI Guoqiang; WANG Zhongke

    2010-01-01

    Based on observations of runoff plots and field investigations of gully cross-sections, impacts of various soil and water conservation measures on runoff and sediment yield are analyzed for different rainfall conditions. The results show that antecedent rainfall and rainfall intensity are the main factors affecting the runoff and soil erosion processes. Rainfall events with antecedent rainfall can produce high runoff and sediment yield. Large differences in the characteristics of two rainfall events will result in greater variations of total runoff and sediment yield from the same runoff plot. Under the same soil control measure and rainfall condition, soil and water conservation measures can reduce the impacts of antecedent rainfall and rainfall intensity on runoff and soil erosion. Among various measures, level terrace seems to be the greatest for soil conservation purposes. Combining with engineering measures,Vegetation measures is also effective in controlling runoff and soil erosion. In the initial stage of vegetation enclosure measures, engineering measure is necessary to improve the environment for ecological recovery. Gully head protection can control gully erosion effectively, but the effectiveness of gully head protection would be reduced when rainfall intensity increases. Therefore, the design of a gully head protection structure must be based on local hydrological conditions.

  4. Erosion and Soil Contamination Control Using Coconut Flakes And Plantation Of Centella Asiatica And Chrysopogon Zizanioides

    Science.gov (United States)

    Roslan, Rasyikin; Che Omar, Rohayu; Nor Zuliana Baharuddin, Intan; Zulkarnain, M. S.; Hanafiah, M. I. M.

    2016-11-01

    Land degradation in Malaysia due to water erosion and water logging cause of loss of organic matter, biodiversity and slope instability but also land are contaminated with heavy metals. Various alternative such as physical remediation are use but it not showing the sustainability in term of environmental sustainable. Due to that, erosion and soil contamination control using coconut flakes and plantation of Centella asiatica and Chrysopogon zizanioides are use as alternative approach for aid of sophisticated green technology known as phytoremediation and mycoremediation. Soil from cabonaceous phyllite located near to Equine Park, Sri Kembangan are use for monitoring the effect of phytoremediation and mycoremediation in reducing soil contamination and biotechnology for erosion control. Five laboratory scale prototypes were designed to monitor the effect of different proportion of coconut flakes i.e. 10%, 25%, 50% & 100% and plantation of Centella asiatica and Chrysopogon zizanioides to reduce the top soil from eroding and reduce the soil contamination. Prototype have been observe started from first week and ends after 12 weeks. Centella asiatica planted on 10% coconut flakes with 90% soil and Chrysopogon zizanioides planted on 25% coconut flakes with 75% soil are selected proportion to be used as phytoremediation and mycoremediation in reducing soil contamination and biotechnology for erosion control.

  5. Measurement of erosion: Is it possible?

    NARCIS (Netherlands)

    Stroosnijder, L.

    2005-01-01

    Reasons for erosion measurements are: (1) to determine the environmental impact of erosion and conservation practices, (2) scientific erosion research; (3) development and evaluation of erosion control technology; (4) development of erosion prediction technology and (5) allocation of conservation

  6. Measurement of erosion: Is it possible?

    NARCIS (Netherlands)

    Stroosnijder, L.

    2005-01-01

    Reasons for erosion measurements are: (1) to determine the environmental impact of erosion and conservation practices, (2) scientific erosion research; (3) development and evaluation of erosion control technology; (4) development of erosion prediction technology and (5) allocation of conservation re

  7. Soil erosion and sediment control laws. A review of state laws and their natural resource data requirements

    Science.gov (United States)

    Klein, S. B.

    1980-01-01

    Twenty states, the District of Columbia, and the Virgin Islands enacted erosion and sediment control legislation during the past decade to provide for the implementation or the strengthening of statewide erosion and sediment control plans for rural and/or urban lands. That legislation and the state programs developed to implement these laws are quoted and reviewed. The natural resource data requirements of each program are also extracted. The legislation includes amendments to conservation district laws, water quality laws, and erosion and sediment control laws. Laws which provides for legislative review of administrative regulations and LANDSAT applications and/or information systems that were involved in implementing or gathering data for a specific soil erosion and sediment control program are summarized as well as principal concerns affecting erosion and sediment control laws.

  8. Chosing erosion control nets. Can't you decide? Ask the lab.

    Science.gov (United States)

    Simkova, Jana; Jacka, Lukas

    2015-04-01

    Geotextiles (GTXs) have been used to protect steep slopes against soil erosion for about 60 years and many products have become available. The choice of individual product is always based on its ratio of cost versus effectiveness. Generally applicable recommendations for specific site conditions are missing and testing the effectiveness of GTXs in the field is time consuming and costly. Due to various site conditions, results of numerous case-studies cannot be generalized. One of the major and site-specific factors affecting the erosion process, and hence the effectiveness of GTXs, is the soil. This study aimed to determine the rate of influence of three natural erosion control nets on the volume and velocity of surface runoff caused by rainfall. The nets were installed on slope under laboratory conditions and then exposed to simulated rainfall. An impermeable plastic film was used as a substrate instead of soil to simulate non-infiltrating conditions. A comparison of the influence of tested GTX samples on surface runoff may indicate to their erosion control effect. Thus, the results could help with choosing a particular product. Under real conditions, the effect of erosion control nets would be increased by the infiltration capacity of the soil, equally for all samples. Therefore, the order of effectiveness of the samples should stay unchanged. To validate this theory, a field experiment was carried out where soil loss was recorded along with runoff characteristics. The data trends of discharge culmination under natural conditions were similar to trends under laboratory conditions and corresponded to soil loss records.

  9. Reduction Effect Analysis of Erosion Control Facilities Using Debris Flow Numerical Model

    Science.gov (United States)

    Jun, Kyewon; Kim, Younghwan; Oh, Chaeyeon; Lee, Hojin; Kim, SoungDoug

    2017-04-01

    With the increase in frequency of typhoons and heavy rains following the climate change, the scale of damage from the calamities in the mountainous areas has been growing larger and larger, which is different from the past. For the case of Korea where 64% of land is consisted of the mountainous areas, establishment of the check dams has been drastically increased after 2000 in order to reduce the damages from the debris flow. However, due to the lack of data on scale, location and kind of check dams established for reducing the damages in debris flow, the measures to prevent damages based on experience and subjective basis have to be relied on. This study, the high-precision DEM data was structured by using the terrestrial LiDAR in the Jecheon area where the debris flow damage occurred in July 2009. And, from the numerical models of the debris flow, Kanako-2D that is available to reflect the erosion and deposition action was applied to install the erosion control facilities (water channel, check dam) and analyzed the effect of reducing the debris flow shown in the downstream. After installing the erosion control facilities, most of debris flow moves along the water channel to reduce the area to expand the debris flow, and after installing the check dam, the flow depth and flux of the debris flow were reduced along with the erosion. However, even after constructing the erosion control facilities, damages were still inflicted on private residences or agricultural sites located on the upper regions where the deposition was made. Acknowledgments This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(NRF-2016R1D1A3B03933362)

  10. Experimental active control results from the SPICES smart structure demonstrations

    Science.gov (United States)

    Flamm, David S.; Toth, G. K.; Chou, Kenneth C.; Heck, Larry P.; Nowlin, William C.; Titterton, Paul J., Sr.

    1996-05-01

    The final demonstrations of the ARPA SPICES (Synthesis and Processing of Intelligent Cost Effective Structures) program test the control of two active vibration mounts manufactured from composites with embedded actuators and sensors. Both mount demonstrations address wide band control problems for real disturbances, one at low frequency and the other at high frequency. The control systems for both are two-level hierarchies, with an inner active damping augmentation loop and an outer vibration control loop. We first review the control design requirements for the demonstration and summarize our control design approach. Then we focus on presenting the experimental results of the final demonstrations. For the low frequency demonstration, two alternative control approaches were demonstrated, one involving finite impulse response modeling and the other state space modeling. For the high frequency demonstration only the finite impulse response modeling approach was used because of computational limitations due to the complex system dynamics.

  11. Native Roadside Vegetation that Enhances Soil Erosion Control in Boreal Scandinavia

    Directory of Open Access Journals (Sweden)

    Annika K. Jägerbrand

    2014-07-01

    Full Text Available This study focused on identifying vegetation characteristics associated with erosion control at nine roadside sites in mid-West Sweden. A number of vegetation characteristics such as cover, diversity, plant functional type, biomass and plant community structure were included. Significant difference in cover between eroded and non-eroded sub-sites was found in evergreen shrubs, total cover, and total above ground biomass. Thus, our results support the use of shrubs in order to stabilize vegetation and minimize erosion along roadsides. However, shrubs are disfavored by several natural and human imposed factors. This could have several impacts on the long-term management of roadsides in boreal regions. By both choosing and applying active management that supports native evergreen shrubs in boreal regions, several positive effects could be achieved along roadsides, such as lower erosion rate and secured long-term vegetation cover. This could also lead to lower costs for roadside maintenance as lower erosion rates would require less frequent stabilizing treatments and mowing could be kept to a minimum in order not to disfavor shrubs.

  12. Rock-type control on erosion-induced uplift, eastern Swiss Alps

    Science.gov (United States)

    Korup, Oliver; Schlunegger, Fritz

    2009-02-01

    There is growing evidence that Quaternary rock uplift in parts of the European Alps is a consequence of climate- and erosion-driven isostatic rebound. Contemporary rates of rock uplift U in the Swiss Alps show two distinctive dome-like peak regions that attain ~ 1.6 mm yr - 1 . We focus on the Alpenrhein catchment and its surroundings, where one of these peak regions spatially coincides with widely exposed Cretaceous Bündner schist and lower Tertiary flysch. Field assessments and analyses of hillslope gradient distributions quantitatively demonstrate the low rock-mass strength and high erodibility of these rocks. This is reflected in mean postglacial catchment erosion rates D ~ 4 mm yr - 1 , as opposed to 0.7 mm yr - 1 in more resistant crystalline rocks. Though largely inferred from landslide- and debris-flow prone tributary catchments export, from the region. We further find that the steepness of bedrock rivers, the density of large landslides, and D correlate with the highest values of U. Our observations highlight the possibility that erosion of mechanically weak Bündner schist and flysch enhanced by large landslides may have contributed to regional crustal unloading, and concomitant rock uplift. Irrespective of whether this is betraying a coupling between long-term uplift and erosion modulated by rock type, our findings indicate that long-term (10 3 to 10 4 yr) geomorphic signals contained in bedrock-river steepness, spatial density of large landslides, and postglacial erosion rates strikingly correlate with regional gradients of historic (10 1 yr) rock uplift rates.

  13. Evaluation of different techniques for erosion control on different roadcuts in its first year of implantation

    Science.gov (United States)

    Gomez, Jose Alfonso; Rodríguez, Abraham; Viedma, Antonio; Contreras, Valentin; Vanwalleghem, Tom; Taguas, Encarnación V.; Giráldez, Juan Vicente

    2014-05-01

    Linear infrastructures, such as highways and railways, present a large environmental impact. Among this impact is the effect on landscape and the modification of the hydrological conditions of the area and an increase in erosive processes (Martin et al., 2011). The increase of erosive processes is specially significant in roadbanks, resulting in high maintenance costs as well as security risks for the use of the infrastructure if it is not properly controlled. Among roadbanks, roadcuts are specially challenging areas for erosion control and ecological restoration, due to their usually steep slope gradient and poor conditions for establishment of vegetation. There are several studies in Mediterranean conditions indicating how the combination of semiarid conditions with, sporadic, intense rainfall events makes a successful vegetation development and erosion control in motorway roadbanks extremely difficult (e.g. Andrés and Jorbat, 2000; Bochet and García-Fayos, 2004). This communication presents the results of the first year evaluation (hydrological year 2012-2013) of five different erosion control strategies on six different locations under different materials on roadcuts of motorways or railways in Andalusia during 2012-2013 using natural rainfall and simulated rainfall. The six sites were located on roadcuts between 10 and 20 m long on slope steepness ranging from 40 to 90%, in motorways and railways spread over different materials in Andalusia. Site 1, Huelva was located on consolidated sand material, sites 2, Osuna I, site 3, Osuna II and site 4, Mancha Real, on marls. Sites 5, Guadix, and 6, Fiñana, were located on phyllites, in comparison a harder material. At each site 12 plots (10 m long and 2 m wide) were installed using metal sheets buried 10 cm within the soil with their longest side in the direction of the roadcut maximum slope. Six different treatments were evaluated at each site, two replications each. These treatments were: 1- A control with bare

  14. Construction and Application of Soil Erosion Control and Circular Agriculture Mode in Hilly Red Soil of Southern China

    Institute of Scientific and Technical Information of China (English)

    Boqi WENG; Zhenmei ZHONG; Xuhui LUO; Zhaoyang YING; Yixiang WANG; Jing YE

    2012-01-01

    Abstract [Objective] The paper was to construct agriculture mode in hilly red [Method] The cause of soil soil of southern China, erosion in hilly red so soil erosion control and circular and analyze its application effort. of southern China and the rea- son for long-term treatment without remarkable effort were analyzed. On this basis, the key technology, economic benefit, ecological service function and carbon se- questration sink enhancement effect of various modes were further analyzed. [Result] The basic idea for comprehensive control of hilly soil erosion in southern China was as follows: the control of soil erosion was combined with modern agricultural produc- tion, in order to build "fruit (tea)-grass-livestock-methane" circular agriculture mode with comprehensive control of soil erosion; application effect analysis showed that the establishment of circular agriculture mode in southern hilly area to control soil erosion ~lad remarkable effect, which could simultaneously meet the coordinated de- velopment of ecological, economic and social benefits. [Conclusion] This study estab- lished an effective mode suitable for soil erosion control and agricultural protection development in southern red soil mountain, which could drive the sustainable devel- opment of ecological restoration of mountainous area and rural agricultural economy.

  15. [Mechanisms of grass in slope erosion control in Loess sandy soil region of Northwest China].

    Science.gov (United States)

    Zhao, Chun-Hong; Gao, Jian-En; Xu, Zhen

    2013-01-01

    By adopting the method of simulated precipitation and from the viewpoint of slope hydrodynamics, in combining with the analysis of soil resistance to erosion, a quantitative study was made on the mechanisms of grass in controlling the slope erosion in the cross area of wind-water erosion in Loess Plateau of Northwest China under different combinations of rainfall intensity and slope gradient, aimed to provide basis to reveal the mechanisms of vegetation in controlling soil erosion and to select appropriate vegetation for the soil and water conservation in Loess Plateau. The grass Astragalus adsurgens with the coverage about 40% could effectively control the slope erosion. This grass had an efficiency of more than 70% in reducing sediment, and the grass root had a greater effect than grass canopy. On bare slope and on the slopes with the grass plant or only the grass root playing effect, there existed a functional relation between the flow velocity on the slopes and the rainfall intensity and slope gradient (V = DJ(0.33 i 0.5), where V is flow velocity, D is the comprehensive coefficient which varies with different underlying surfaces, i is rainfall intensity, and J is slope gradient). Both the grass root and the grass canopy could markedly decrease the flow velocity on the slopes, and increase the slope resistance, but the effect of grass root in decreasing flow velocity was greater while the effect in increasing resistance was smaller than that of grass canopy. The effect of grass root in increasing slope resistance was mainly achieved by increasing the sediment grain resistance, while the effect of canopy was mainly achieved by increasing the slope form resistance and wave resistance. The evaluation of the soil resistance to erosion by using a conceptual model of sediment generation by overland flow indicated that the critical shear stress value of bare slope and of the slopes with the grass plant or only the grass root playing effect was 0.533, 1.672 and 0

  16. Managing the Arroyo Seco for Flood Prevention, Erosion Control, Waterway and Habitat Restoration

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, L; Wang, C; Laurant, J

    2003-02-06

    One of the most important tasks for a site facility manager is to ensure that appropriate channel erosion controls are applied to on-site drainage channels. These erosion controls must minimize risks to the public and structures. Water and sediment loads commonly originate from off-site sources and many of the traditional reactionary measures (installing rip-rap or some other form of bed or bank armor) simply transfer or delay the problem. State and federal agency requirements further complicate the management solution. One case in point is the Arroyo Seco, an intermittent stream that runs along the southwest corner of the Lawrence Livermore National Laboratory (LLNL) in Livermore, California. In 2001, LLNL contracted Questa Engineering Corporation to conduct hydraulic, geomorphic, and biological investigations and to prepare an alternatives and constraints analysis. From these investigations, LLNL has selected a water management plan that encompasses overall flood prevention, erosion control, and waterway and habitat restoration and enhancement elements. The most unique aspect of the Arroyo Seco management plan is its use of non-traditional and biotechnical techniques.

  17. The history and assessment of effectiveness of soil erosion control measures deployed in Russia

    Directory of Open Access Journals (Sweden)

    Valentin Golosov

    2013-09-01

    Full Text Available Research activities aimed at design and application of soil conservation measures for reduction of soil losses from cultivated fields started in Russia in the last quarter of the 19th century. A network of "zonal agrofor-estry melioration experimental stations" was organized in the different landscape zones of Russia in the first half of the 20th century. The main task of the experiments was to develop effective soil conservation measures for Russian climatic,soil and land use conditions. The most widespread and large-scale introduction of coun-termeasures to cope with soil erosion by water and wind into agricultural practice supported by serious governmental investments took place during the Soviet Union period after the Second World War. After the Soviet Union collapse in 1991 ,general deterioration of the agricultural economy sector and the absence of investments resulted in cessation of organized soil conservation measures application at the nation-wide level. However, some of the long-term erosion control measures such as forest shelter belts, artificial slope terracing, water diversion dams above formerly active gully heads survived until the present. In the case study of sediment redistribution within the small cultivated catchment presented in this paper an attempt was made to evaluate average annual erosion rates on arable slopes with and without soil conservation measures for two time intervals. It has been found that application of conservation measures on cultivated slopes within the experimental part of the case study catchment has led to a decrease of average soil loss rates by at least 2. 5 2. 8 times. The figures obtained are in good agreement with previously published results of direct monitoring of snowmelt erosion rates, reporting approximately a 3 -fold decrease of average snowmelt erosion rates in the experimental sub-catchment compared to a traditionally cultivated control sub-catchment. A substantial decrease of soil

  18. Optimal land use management for soil erosion control by using an interval-parameter fuzzy two-stage stochastic programming approach.

    Science.gov (United States)

    Han, Jing-Cheng; Huang, Guo-He; Zhang, Hua; Li, Zhong

    2013-09-01

    Soil erosion is one of the most serious environmental and public health problems, and such land degradation can be effectively mitigated through performing land use transitions across a watershed. Optimal land use management can thus provide a way to reduce soil erosion while achieving the maximum net benefit. However, optimized land use allocation schemes are not always successful since uncertainties pertaining to soil erosion control are not well presented. This study applied an interval-parameter fuzzy two-stage stochastic programming approach to generate optimal land use planning strategies for soil erosion control based on an inexact optimization framework, in which various uncertainties were reflected. The modeling approach can incorporate predefined soil erosion control policies, and address inherent system uncertainties expressed as discrete intervals, fuzzy sets, and probability distributions. The developed model was demonstrated through a case study in the Xiangxi River watershed, China's Three Gorges Reservoir region. Land use transformations were employed as decision variables, and based on these, the land use change dynamics were yielded for a 15-year planning horizon. Finally, the maximum net economic benefit with an interval value of [1.197, 6.311] × 10(9) $ was obtained as well as corresponding land use allocations in the three planning periods. Also, the resulting soil erosion amount was found to be decreased and controlled at a tolerable level over the watershed. Thus, results confirm that the developed model is a useful tool for implementing land use management as not only does it allow local decision makers to optimize land use allocation, but can also help to answer how to accomplish land use changes.

  19. Performance and efficiency of geotextile-supported erosion control measures during simulated rainfall events

    Science.gov (United States)

    Obriejetan, Michael; Rauch, Hans Peter; Florineth, Florin

    2013-04-01

    Erosion control systems consisting of technical and biological components are widely accepted and proven to work well if installed properly with regard to site-specific parameters. A wide range of implementation measures for this specific protection purpose is existent and new, in particular technical solutions are constantly introduced into the market. Nevertheless, especially vegetation aspects of erosion control measures are frequently disregarded and should be considered enhanced against the backdrop of the development and realization of adaptation strategies in an altering environment due to climate change associated effects. Technical auxiliaries such as geotextiles typically used for slope protection (nettings, blankets, turf reinforcement mats etc.) address specific features and due to structural and material diversity, differing effects on sediment yield, surface runoff and vegetational development seem evident. Nevertheless there is a knowledge gap concerning the mutual interaction processes between technical and biological components respectively specific comparable data on erosion-reducing effects of technical-biological erosion protection systems are insufficient. In this context, an experimental arrangement was set up to study the correlated influences of geotextiles and vegetation and determine its (combined) effects on surface runoff and soil loss during simulated heavy rainfall events. Sowing vessels serve as testing facilities which are filled with top soil under application of various organic and synthetic geotextiles and by using a reliable drought resistant seed mixture. Regular vegetational monitoring as well as two rainfall simulation runs with four repetitions of each variant were conducted. Therefore a portable rainfall simulator with standardized rainfall intensity of 240 mm h-1 and three minute rainfall duration was used to stress these systems on different stages of plant development at an inclination of 30 degrees. First results show

  20. Runoff erosion

    OpenAIRE

    Evelpidou, Niki; Cordier, Stephane; Merino, Agustin (Ed.); Figueiredo, Tomás; Centeri, Csaba

    2013-01-01

    Table of Contents PART I – THEORY OF RUNOFF EROSION CHAPTER 1 - RUNOFF EROSION – THE MECHANISMS CHAPTER 2 - LARGE SCALE APPROACHES OF RUNOFF EROSION CHAPTER 3 - MEASURING PRESENT RUNOFF EROSION CHAPTER 4 - MODELLING RUNOFF EROSION CHAPTER 5 - RUNOFF EROSION AND HUMAN SOCIETIES: THE INFLUENCE OF LAND USE AND MANAGEMENT PRACTICES ON SOIL EROSION PART II - CASE STUDIES CASE STUDIES – INTRODUCTION: RUNOFF EROSION IN MEDITERRANEAN AREA CASE STUDY 1: Soil Erosion Risk...

  1. The contribution of mulches to control high soil erosion rates in vineyards in Eastern Spain

    Science.gov (United States)

    Cerdà, Artemi; Jordán, Antonio; Zavala, Lorena; José Marqués, María; Novara, Agata

    2014-05-01

    Soil erosion take place in degraded ecosystem where the lack of vegetation, drought, erodible parent material and deforestation take place (Borelli et al., 2013; Haregeweyn et al., 2013; Zhao et al., 2013). Agriculture management developed new landscapes (Ore and Bruins, 2012) and use to trigger non-sustainable soil erosion rates (Zema et al., 2012). High erosion rates were measured in agriculture land (Cerdà et al., 2009), but it is also possible to develop managements that will control the soil and water losses, such as organic amendments (Marqués et al., 2005), plant cover (Marqués et al., 2007) and geotextiles (Giménez Morera et al., 2010). The most successful management to restore the structural stability and the biological activity of the agriculture soil has been the organic mulches (García Orenes et al; 2009; 2010; 2012). The straw mulch is also very successful on bare fire affected soil (Robichaud et al., 2013a; 2013b), which also contributes to a more stable soil moisture content (García-Moreno et al., 2013). The objective of this research is to determine the impact of two mulches: wheat straw and chipped branches, on the soil erosion rates in a rainfed vineyard in Eastern Spain. The research site is located in the Les Alcusses Valley within the Moixent municipality. The Mean annual temperature is 13 ºC, and the mean annual rainfall 455 mm. Soil are sandy loam, and are developed at the foot-slope of a Cretaceous limestone range, the Serra Grossa range. The soils use to be ploughed and the features of soil erosion are found after each thunderstorm. Rills are removed by ploughing. Thirty rainfall simulation experiments were carried out in summer 2011 during the summer drought period. The simulated rainfall lasted during 1 hour at a 45 mmh-1 intensity on 1 m2 plots (Cerdà and Doerr, 2010; Cerdà and Jurgensen 2011). Ten experiments were carried out on the control plots (ploughed), 10 on straw mulch covered plots, and 10 on chipped branches covered

  2. Distinguishing between tectonic and lithologic controls on bedrock channel longitudinal profiles using cosmogenic 10Be erosion rates and channel steepness index

    Science.gov (United States)

    Cyr, Andrew J.; Granger, Darryl E.; Olivetti, Valerio; Molin, Paola

    2014-01-01

    Knickpoints in fluvial channel longitudinal profiles and channel steepness index values derived from digital elevation data can be used to detect tectonic structures and infer spatial patterns of uplift. However, changes in lithologic resistance to channel incision can also influence the morphology of longitudinal profiles. We compare the spatial patterns of both channel steepness index and cosmogenic 10Be-determined erosion rates from four landscapes in Italy, where the geology and tectonics are well constrained, to four theoretical predictions of channel morphologies, which can be interpreted as the result of primarily tectonic or lithologic controls. These data indicate that longitudinal profile forms controlled by unsteady or nonuniform tectonics can be distinguished from those controlled by nonuniform lithologic resistance. In each landscape the distribution of channel steepness index and erosion rates is consistent with model predictions and demonstrates that cosmogenic nuclide methods can be applied to distinguish between these two controlling factors.

  3. Costs and benefits of urban erosion and sediment control: The North Carolina experience

    Science.gov (United States)

    Paterson, Robert G.; Luger, Michael I.; Burby, Raymond J.; Kaiser, Edward J.; Malcom, H. Rooney; Beard, Alicia C.

    1993-03-01

    The EPA’s new nonpoint source pollution control requirements will soon institutionalize urban erosion and sediment pollution control practices nationwide. The public and private sector costs and social benefits associated with North Carolina’s program (one of the strongest programs in the country in terms of implementation authority, staffing levels, and comprehensiveness of coverage) are examined to provide general policy guidance on questions relating to the likely burden the new best management practices will have on the development industry, the likely costs and benefits of such a program, and the feasibility of running a program on a cost recovery basis. We found that urban erosion and sediment control requirements were not particularly burdensome to the development industry (adding about 4% on average to development costs). Public-sector program costs ranged between 2.4 and 4.8 million in fiscal year 1989. Our contingent valuation survey suggests that urban households in North Carolina are willing to pay somewhere between 7.1 and 14.2 million a year to maintain current levels of sediment pollution control. Our benefit-cost analysis suggests that the overall ratio is likely to be positive, although a definitive figure is elusive. Lastly, we found that several North Carolina localities have cost recovery fee systems that are at least partially self-financing.

  4. Fail-Safe Magnetic Bearing Controller Demonstrated Successfully

    Science.gov (United States)

    Choi, Benjamin B.; Provenza, Andrew J.

    2001-01-01

    The Structural Mechanics and Dynamics Branch has successfully demonstrated a fail-safe controller for the Fault-Tolerant Magnetic Bearing rig at the NASA Glenn Research Center. The rotor is supported by two 8-pole redundant radial bearings, and coil failing situations are simulated by manually shutting down their control current commands from the controller cockpit. The effectiveness of the controller was demonstrated when only two active coils from each radial bearing could be used (that is, 14 coils failed). These remaining two coils still levitated the rotor and spun it without losing stability or desired position up to the maximum allowable speed of 20,000 rpm.

  5. Monsoonal versus Anthropogenic Controls on Erosion Patterns and Sediment Flux in the Song Gianh, Vietnam

    Science.gov (United States)

    Clift, Peter; Jonell, Tara; Carter, Andrew; Van Hoang, Long; Böning, Philipp

    2016-04-01

    The Song Gianh is a small drainage on the northern central coast of Vietnam that delivers sediment into the Gulf of Tonkin. The basin provides the opportunity to evaluate what surface processes control continental erosion rates and patterns because there is a strong monsoonal precipitation gradient from the SW to NE. We apply several complimentary provenance methods to modern siliciclastic sediments of the Song Gianh to pinpoint regions of focused sediment generation and evaluate how sediment is mixed downstream and delivered to the ocean. We find that detrital zircon populations of Song Gianh main channel change radically downstream of the confluence with the northern Rao Tro tributary, which is dominated by 100-300 Ma grains eroded from granite bedrock. This tributary provides almost as much zircon to the main channel as all the headwater tributaries combined, despite being a much smaller, drier, and flatter sub-basin. In contrast, bulk sediment Nd and Sr isotopes indicate that most sediment is derived from the wetter headwater tributaries. Contribution from the southern tributaries to the net siliciclastic river flux is negligible. Precipitation and topography do not appear to modulate zircon production in the modern river although regions controlling bulk Nd and Sr compositions are wetter and have higher local relief. This apparent contrast in regions of sediment production suggests disequilibrium and differential travel times for zircon and mineral phases rich in Nd and Sr. Optically Stimulated Luminescence (OSL) dating of alluvial terraces on the main channel show that the valleys aggraded rapidly from ~7-9 ka during a period of strong summer monsoon, suggesting that heavy rainfall generated large sediment volumes. Younger terraces dated to 500-1000 yrs BP are interpreted to reflect erosion and aggradation driven by extensive human agriculture. We speculate that agriculture, together with bedrock compositions, are the most likely control on producing the

  6. NATURAL AND ANTHROPOGENIC FACTORS CONTROLLING GULLY EROSION IN THEBASALTIC UPLAND OF SOUTHERN BRAZIL

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This paper describes an analysis of natural and anthropogenic factors controlling the evolution of gullies in a rural basin in the basaltic upland in the State of Rio Grande do Sul, Southern Brazil. In this region of deep ferrallitic soils with more than 60% clay, runoff and erosion are of increasing concern. In the Tabo(a)o drainage basin (100 km2), gully erosion was studied in a field survey that measured rills and gullies. Eighty-four gullies were identified. They had an average length of 136 m, were 10 m wide, and 3 m deep and had a volume of 15.458 m3. Each gully was characterised in terms of factors that included slope, geological structure, presence of piping, drainage, soil use, and the presence of surface and subsurface flow. On average, the main channels had knickpoints varying from 2 m to 7 m, and their evolution in the vertical plane increased until bed-rock basalt material was reached, after which gullies increase in width and length. Gully development was also monitored from 1991 to 2003. Subsurface flow appears to be the principal agent controlling their development. Results show that both natural (slope, surface curvature, geological structure and rainfall) and anthropogenic (soil use, road construction) factors are important in gully development. The change in cultural practices throughout the drainage basin from conventional to direct seeding has led to increased subsurface flow, which was more important than surface runoff in causing erosion. However, the higher rainfall during El Ni(n)o Southern Oscillation (ENSO) events and the consequently higher subsurface flow were the dominant factors. From 1991 to 2003 a total land loss of 1,013 m3 was observed in one gully, with 236 m3 lost during the 1992 ENSO and 702 m3 during the 1997 ENSO; 95% of the total volume lost occurred during ENSO periods.

  7. Experimental demonstration of coherent feedback control on optical field squeezing

    CERN Document Server

    Iida, Sanae; Yonezawa, Hidehiro; Yamamoto, Naoki; Furusawa, Akira

    2011-01-01

    Coherent feedback is a non-measurement based, hence a back-action free, method of control for quantum systems. A typical application of this control scheme is squeezing enhancement, a purely non-classical effect in quantum optics. In this paper we report its first experimental demonstration that well agrees with the theory taking into account time delays and losses in the coherent feedback loop. The results clarify both the benefit and the limitation of coherent feedback control in a practical situation.

  8. CONTROL OF EROSION PROCESSES RESULTING FROM DISRUPTION OF ADDUCTOR IN THE SERRA DA MANTIQUEIRA, SP, BRAZIL

    Directory of Open Access Journals (Sweden)

    Admilson Clayton Barbosa

    2010-12-01

    Full Text Available In the southern escarpment of the Serra da Mantiqueira, northeast geographic divider between the State of São Paulo and Minas Gerais, there was an environmental accident caused by the disruption of an adductor whose purpose is to lead the water from a reservoir located at an altitude of 1820 m to the machine house where there is an electric generator located at 750 m.  This accident resulted in the formation of a scar on the hillside forest, with removal of soil and vegetation. To reverse the erosion processes, a methodology was developed consisting of the use of four barriers (numbered I to IV formed by seedlings of Bambusa mutiplex (Lour., whose purpose was to divert the water runoff in order to provide the regeneration of native vegetation. Stalks of bamboo intercropped with Bambusa multiplex were used to contain debris in two gullies formed by erosion. The development of vegetation was monitored for 18 months and evaluated by the application of a Leopold Matrix composed of 5 points, which are: erosion, regeneration of vegetation, success of bamboo planting, installed conservation structures and functionality. The purpose of the matrix was to demonstrate the effectiveness of interventions using bamboo. The result of the classification matrix enabled the quantitative and qualitative classification of the interventions, resulting in five levels, where the barriers I, II and IV were considered to be of very high efficiency, and barrier III was considered to be of high efficiency. The contention of the gully was considered to be of medium to very high efficiency.

  9. Factors controlling volume errors through 2D gully erosion assessment: guidelines for optimal survey design

    Science.gov (United States)

    Castillo, Carlos; Pérez, Rafael

    2017-04-01

    The assessment of gully erosion volumes is essential for the quantification of soil losses derived from this relevant degradation process. Traditionally, 2D and 3D approaches has been applied for this purpose (Casalí et al., 2006). Although innovative 3D approaches have recently been proposed for gully volume quantification, a renewed interest can be found in literature regarding the useful information that cross-section analysis still provides in gully erosion research. Moreover, the application of methods based on 2D approaches can be the most cost-effective approach in many situations such as preliminary studies with low accuracy requirements or surveys under time or budget constraints. The main aim of this work is to examine the key factors controlling volume error variability in 2D gully assessment by means of a stochastic experiment involving a Monte Carlo analysis over synthetic gully profiles in order to 1) contribute to a better understanding of the drivers and magnitude of gully erosion 2D-surveys uncertainty and 2) provide guidelines for optimal survey designs. Owing to the stochastic properties of error generation in 2D volume assessment, a statistical approach was followed to generate a large and significant set of gully reach configurations to evaluate quantitatively the influence of the main factors controlling the uncertainty of the volume assessment. For this purpose, a simulation algorithm in Matlab® code was written, involving the following stages: - Generation of synthetic gully area profiles with different degrees of complexity (characterized by the cross-section variability) - Simulation of field measurements characterised by a survey intensity and the precision of the measurement method - Quantification of the volume error uncertainty as a function of the key factors In this communication we will present the relationships between volume error and the studied factors and propose guidelines for 2D field surveys based on the minimal survey

  10. Integrated Prevention and Control System for Soil Erosion in Typical Black Soil Region of Northeast China

    Institute of Scientific and Technical Information of China (English)

    SUN Li-ying; CAI Qiang-guo; CHEN Sheng-yong; HE Ji-jun

    2012-01-01

    The black soil region of Northeast China is one of the most important food production bases and commodity grain bases in China. However, the continual loss and degradation of precious black soil resources has led to direct threats to national food security and regional sustainable development. Therefore, it is necessary to summarize integrated prevention and control experience of small watersheds in black soil region of Northeast China. Tongshuang small watershed, a typical watershed in rolling hills of typical black soil areas in Northeast China, is selected as the study area. Based on nearly 50 years’ experience in prevention and control of soil and water loss, the structures and overall benefits of an integrated prevention and control system for soil and water loss are investigated. Then, the ’three defense lines’ tri-dimensional protection system with reasonable allocation of different types of soil and water control measures from the hill top to gully is systematically analyzed. The first line on the top hill can weaken and block uphill runoff and sediment, hold water resources and improve soil property. The second line on the hill can truncate slope length, slow down the runoff velocity and reduce erosion energy. The third line in the gully is mainly composed of waterfall engineering, which can inhibit soil erosion and restore land resources. The ’three defense lines’ system is feasible for soil and water loss control of small watersheds in the typical black soil region of Northeast China. Through the application of the in Tongshuang small watershed, There are effective improvements in ecological conditions in Tongshuang small watershed after the application of ’three defense lines’ soil and water control system. Moreover, the integrated treatment paradigm for soil and water loss in typical black soil region is compared with that in loess region. The results of this study could offer references and experiences for other small watersheds in

  11. Robotic weld overlay coatings for erosion control. Final technical progress report, July 1992--July 1995

    Energy Technology Data Exchange (ETDEWEB)

    Levin, B.F.; DuPont, J.N.; Marder, A.R.

    1995-10-15

    The erosion behavior of weld overlay coatings has been studied. Eleven weld overlay alloys were deposited on 1018 steel substrates using the plasma arc welding process and erosion tested at 400{degrees}C at 90{degrees} and 30{degrees} particle impact angles. The microstructure of each coating was characterized before erosion testing. A relative ranking of the coatings erosion resistance was developed by determining the steady state erosion rates. Ultimet, Inconel-625, and 316L SS coatings showed the best erosion resistance at both impact angles. It was found that weld overlays that exhibit good abrasion resistance did not show good erosion resistance. Erosion tests were also performed for selected wrought materials with chemical composition similar to weld overlays. Eroded surfaces of the wrought and weld alloys were examined by Scanning Electron Microscopy (SEM). Microhardness tests were performed on the eroded samples below the erosion surface to determine size of the plastically deformed region. It was found that one group of coatings experienced significant plastic deformation as a result of erosion while the other did not. It was also established that, in the steady state erosion regime, the size of the plastically deformed region is constant.

  12. Cropping systems and control of soil erosion in a Mediterranean environment

    Science.gov (United States)

    Cosentino, Salvatore; Copani, Venera; Testa, Giorgio; Scalici, Giovanni

    2013-04-01

    The research has been carried out over the years 1996-2010 in an area of the internal hill of Sicily region (Enna, c.da Geracello, 550 m a. s. l. 37° 23' N. Lat, 14° 21' E. Long) in the center of Mediterranean Sea, mainly devoted to durum wheat cultivation, using the experimental plots, established in 1996 on a slope of 26-28%, equipped to determine surface runoff and soil losses. The establishment consists of twelve plots, having 40 m length and 8 m width. In order to study the effect of different field crop systems in controlling soil erosion in slopes subjected to water erosion, the following systems were studied: permanent crops, tilled annual crops, no-tilled annual crops, set-aside. The used crops were: durum wheat, faba bean, rapeseed, subterranean clover, Italian ryegrass, alfalfa, sweetvetch, moon trefoil, barley, sweet sorghum, sunflower. The results pointed out that the cropping systems with perennial crops allowed to keep low the soil loss, while annual crop rotation determined a high amount of soil loss. Sod seeding showed promising results also for annual crop rotations.

  13. Demonstration of Quantum Entanglement Control Using Nuclear Magnetic Resonance

    Institute of Scientific and Technical Information of China (English)

    XIE Jing-Yi; ZHANG Jing-Fu; DENG Zhi-Wei; LU Zhi-Heng

    2004-01-01

    @@ With the two forms of the quantum entanglement control, the quantum entanglement swapping and preservation are demonstrated in a three-qubit nuclear magnetic resonance quantum computer. The pseudopure state is prepared to represent the quantum entangled states through macroscopic signals. Entanglement swapping is directly realized by a swap operation. By controlling the interactions between the system and its environment,we can preserve an initial entangled state for a longer time. The experimental results are in agreement with the experiment.

  14. Extreme soil erosion rates in citrus slope plantations and control strategies. A literature review

    Science.gov (United States)

    Cerdà, Artemi; Ángel González Peñaloza, Félix; Pereira, Paulo; Reyes Ruiz Gallardo, José; García Orenes, Fuensanta; Burguet, María

    2013-04-01

    Soil Erosion is a natural process that shapes the Earth. Due to the impact of agriculture, soil erosion rates increase, landforms show gullies and rills, and soils are depleted. In the Mediterranean, wheat, olive and vineyards were the main agriculture products, but new plantations are being found in sloping terrain due to the drip-irrigation. This new strategy results in the removal of the traditional terraces in order to make suitable for mechanization the agriculture plantation. Citrus is a clear example of the impact of the new chemical agriculture with a high investment in herbicides, pesticides, mechanisation, land levelling and drip computer controlled irrigation systems. The new plantation of citrus orchards is found in the Mediterranean, but also in California, Florida, China and Brazil. Chile, Argentina, and South Africa are other producers that are moving to an industrial production of citrus. This paper shows how the citrus plantations are found as one of the most aggressive plantation due to the increase in soil erosion, and how we can apply successful control strategies. The research into the high erosion rates of citrus orchard built on the slopes are mainly found in China (Wu et al., 1997; Xu et al., 2010; Wang et al., 2011; Wu et al., 2011; Liu et al., 2011; Lü et al., 2011; Xu et al., 2012) and in the Mediterranean (Cerdà and Jurgensen, 2008; 2009; Cerdà et al., 2009a; 2009b; Cerdà et al., 2011; 2012) Most of the research done devoted to the measurements of the soil losses but also some research is done related to the soil properties (Lu et al., 1997; Lü et al., 2012; Xu et al., 2012) and the impact of cover crops to reduce the soil losses (Lavigne et al., 2012; Le Bellec et al., 2012) and the use of residues such as dried citrus peel in order to reduce the soil losses. There are 116 million tonnes of citrus produced yearly, and this affects a large surface of the best land. The citrus orchards are moving from flood irrigated to drip

  15. In Situ analysis of CO2 laser irradiation on controlling progression of erosive lesions on dental enamel.

    Science.gov (United States)

    Lepri, Taísa Penazzo; Scatolin, Renata Siqueira; Colucci, Vivian; De Alexandria, Adílis Kalina; Maia, Lucianne Cople; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

    2014-08-01

    The present study aimed to evaluate in situ the effect of CO2 laser irradiation to control the progression of enamel erosive lesions. Fifty-six slabs of bovine incisors enamel (5 × 3 × 2.5 mm(3) ) were divided in four distinct areas: (1) sound (reference area), (2) initial erosion, (3) treatment (irradiated or nonirradiated with CO2 laser), (4) final erosion (after in situ phase). The initial erosive challenge was performed with 1% citric acid (pH = 2.3), for 5 min, 2×/day, for 2 days. The slabs were divided in two groups according to surface treatment: irradiated with CO2 laser (λ = 10.6 µm; 0.5 W) and nonirradiate. After a 2-day lead-in period, 14 volunteers wore an intraoral palatal appliance containing two slabs (irradiated and nonirradiated), in two intraoral phases of 5 days each. Following a cross-over design during the first intraoral phase, half of the volunteers immersed the appliance in 100 mL of citric acid for 5 min, 3×/day, while other half of the volunteers used deionized water (control). The volunteers were crossed over in the second phase. Enamel wear was determined by an optical 3D profilometer. Three-way ANOVA for repeated measures revealed that there was no significant interaction between erosive challenge and CO2 laser irradiation (P = 0.419). Erosive challenge significantly increased enamel wear (P = 0.001), regardless whether or not CO2 laser irradiation was performed. There was no difference in enamel wear between specimens CO2 -laser irradiated and non-irradiated (P = 0.513). Under intraoral conditions, CO2 laser irradiation did not control the progression of erosive lesions in enamel caused by citric acid. © 2014 Wiley Periodicals, Inc.

  16. Cretaceous reactivation and intensified erosion in the Archean-Proterozoic Limpopo Belt, demonstrated by apatite fission track thermochronology

    Science.gov (United States)

    Belton, David X.; Raab, Matthias J.

    2010-01-01

    Cratons are generally assumed to be regions of long-lasting tectonic stability. In particular the study of the Phanerozoic exhumation history of cratons has been largely hampered by the scarcity of suitable stratigraphic controls onshore. This fact is even more pronounced in terranes lacking Mesozoic or younger penetrative structural fabrics and metamorphic overprinting. Our study in the Limpopo belt shows that modern apatite fission track thermochronology provides a hitherto unavailable perspective in the study of these rocks, and has profound implications for the crustal evolution of the Zimbabwe Craton. Apatite fission track data from 35 samples taken along two transects, in the southern edge of the Zimbabwe Craton and in the Central Zone of the Limpopo Belt, suggest that extensive regions experienced kilometer-scale exhumation in two discrete events, as recently as the Cretaceous. The first occurred at around 130 Ma, and the second at around 90 Ma. Basin subsidence and sedimentation loads on the Mozambique margin support the timing of these events and provide strong indications of the source and pathways for the eroded material. Further, the results indicate that young and old "surfaces" (in a geomorphological sense) may be structurally juxtaposed in regions of high elevation in Zimbabwe. This is contrary to early ideas of surface chronologies based on summit accordances or invoking pediplanation.

  17. A Maine romance. [Solar heating, wind power and cliff erosion control at a Maine site

    Energy Technology Data Exchange (ETDEWEB)

    Adams, J.A.

    1979-09-01

    The construction of a house on the coast of Maine included terracing of the bluff for erosion control, installation of water solar collectors for space and water heating, and construction of a wind turbine for electric power generation. A total of 4,027 ft/sup 2/ of house area is heated by a system of 10 collectors and 4,000 gal water storage. Insulation values are R-19 in the walls, R-40 in the ceiling, R-26 in the floors, and R-14 in the basement. South-facing windows provide additional heat gain. The wind turbine and generator system supplies alternating current to the house and also heats auxiliary water storage when necessary. The house, collectors, and wind turbine are designed to supply 85% of the heating load.

  18. Saltcedar and Russian Olive Control Demonstration Act Science Assessment

    Science.gov (United States)

    Shafroth, Patrick B.; Brown, Curtis A.; Merritt, David M.

    2010-01-01

    The primary intent of this document is to provide the science assessment called for under The Saltcedar and Russian Olive Control Demonstration Act of 2006 (Public Law 109-320; the Act). A secondary purpose is to provide a common background for applicants for prospective demonstration projects, should funds be appropriated for this second phase of the Act. This document synthesizes the state-of-the-science on the following topics: the distribution and abundance (extent) of saltcedar (Tamarix spp.) and Russian olive (Elaeagnus angustifolia) in the Western United States, potential for water savings associated with controlling saltcedar and Russian olive and the associated restoration of occupied sites, considerations related to wildlife use of saltcedar and Russian olive habitat or restored habitats, methods to control saltcedar and Russian olive, possible utilization of dead biomass following removal of saltcedar and Russian olive, and approaches and challenges associated with revegetation or restoration following control efforts. A concluding chapter discusses possible long-term management strategies, needs for additional study, potentially useful field demonstration projects, and a planning process for on-the-ground projects involving removal of saltcedar and Russian olive.

  19. Experimental demonstration of active vibration control for flexible structures

    Science.gov (United States)

    Phillips, Douglas J.; Hyland, David C.; Collins, Emmanuel G., Jr.

    1990-01-01

    Active vibration control of flexible structures for future space missions is addressed. Three experiments that successfully demonstrate control of flexible structures are described. The first is the pendulum experiment. The structure is a 5-m compound pendulum and was designed as an end-to-end test bed for a linear proof mass actuator and its supporting electronics. Experimental results are shown for a maximum-entropy/optimal-projection controller designed to achieve 5 percent damping in the first two pendulum modes. The second experiment was based upon the Harris Multi-Hex prototype experiment (MHPE) apparatus. This is a large optical reflector structure comprising a seven-panel array and supporting truss which typifies a number of generic characteristics of large space systems. The third experiment involved control design and implementation for the ACES structure at NASA Marshall Space Flight Center. The authors conclude with some remarks on the lessons learned from conducting these experiments.

  20. Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project

    Energy Technology Data Exchange (ETDEWEB)

    Stottler, Gary

    2012-02-08

    General Motors, LLC and energy partner Shell Hydrogen, LLC, deployed a system of hydrogen fuel cell electric vehicles integrated with a hydrogen fueling station infrastructure to operate under real world conditions as part of the U.S. Department of Energy's Controlled Hydrogen Fleet and Infrastructure Validation and Demonstration Project. This technical report documents the performance and describes the learnings from progressive generations of vehicle fuel cell system technology and multiple approaches to hydrogen generation and delivery for vehicle fueling.

  1. Controlled erosion in asbestos-cement pipe used in drinking water distribution systems

    Directory of Open Access Journals (Sweden)

    Mariana Ramos, P.

    1990-06-01

    Full Text Available Samples of asbestos-cement pipe used for drinking water conveyance, were submerged in distilled water, and subjected to two controlled erosive treatments, namely agitation (300 rpm for 60 min and ultrasound (47 kHz for 30 min. SEM was used to observe and compare the morphology of the new pipe with and without erosive treatment, and of samples taken from asbestos-cement pipes used in the distribution system of drinking water in Santiago city for 10 and 40-years of service. TEM was used to determine the concentration of asbestos fibers in the test water: 365 MFL and 1690 MFL (millions of fibers per litre as an agitation and result ultrasound, respectively. The erosive treatments by means of agitation or ultrasound applied to new asbestos-cement pipes used in the drinking water distribution system were evaluated as being equivalent to 4 and 10 years of service, respectively.

    Se sometió a dos tratamientos erosivos controlados uno por agitación (300 rpm, 60 min. y otro por ultrasonido (47 kHz, 30 min. a muestras de tubos de asbesto cemento, sumergidas en agua destilada, usados para el trasporte de agua potable. Con SEM se observó la morfología de muestras de tubos sin uso, con y sin tratamiento erosivo y la de muestras extraídas de tubos de asbesto cemento de la red de distribución de agua potable de ía ciudad de Santiago con 10 y 14 años de servicio. Con TEM se determinó la concentración de fibras de asbesto en el agua de ensayo: 365 MFL y 1690 MFL (millones de fibras por litro en agitación y ultrasonido, respectivamente. Se estimó en 4 y 10 años de servicio equivalente los tratamientos erosivos de agitación y ultrasonido, respectivamente en tubos de asbesto cemento empleados en la red de agua potable.

  2. Marginal erosive discovertebral ''Romanus'' lesions in ankylosing spondylitis demonstrated by contrast enhanced Gd-DTPA magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Jevtic, V. [Clinical Radiology Institute, University Clinical Centre, Ljubljana (Slovenia); Kos-Golja, M.; Rozman, B. [Department of Rheumatology, University Clinical Centre, Ljubljana (Slovenia); McCall, I. [Robert Jones and Agnes Hunt Orthopaedic and District Hospital, Oswestry, Shropshire (United Kingdom)

    2000-01-01

    Objective. To assess the value of Gd-DTPA magnetic resonance (MR) imaging in the demonstration of marginal destructive discovertebral Romanus lesions in ankylosing spondylitis.Design and patients. A prospective study of Gd-DTPA MR imaging was performed in 39 patients with a clinical diagnosis of ankylosing spondylitis and typical Romanus lesions seen on radiographs of the thoracolumbar spine. MR morphological appearances and signal intensity changes at the discovertebral junctions were analysed and compared with the radiographic findings.Results. Ninety-nine discovertebral junctions with Romanus lesions showed low signal intensity on T1-weighted and high signal on T2-weighted and T1-weighted postcontrast images at the vertebral corners consistent with oedematous hyperaemic inflammatory tissue. There were nine discovertebral junctions with similar MR findings but normal radiographs. Fifty-three discovertebral junctions showed syndesmophyte formation with increased signal intensity on both T1- and T2-weighted images with no contrast enhancement. Sixty-five discovertebral junctions showed a mixture of radiographic features and varied high and low signal changes at the vertebral rim on MR imaging with rims of enhancement in the vertebral body following contrast administration.Conclusion. Gd-DTPA MR imaging demonstrates a variable signal pattern and degree of contrast enhancement which may reflect the evolutionary stages of discovertebral enthesitis in ankylosing spondylitis. MR imaging may identify early erosive changes in radiographically normal vertebra. The role of MR imaging needs further investigation. (orig.)

  3. The effectiveness of jute and coir blankets for erosion control in different field and laboratory conditions

    Science.gov (United States)

    Kalibová, Jana; Jačka, Lukáš; Petrů, Jan

    2016-03-01

    Vegetation cover is found to be an ideal solution to most problems of erosion on steep slopes. Biodegradable geotextiles (GTXs) have been proved to provide sufficient protection against soil loss in the period before vegetation reaches maturity, so favouring soil formation processes. In this study, 500 g m-2 jute (J500), 400 g m-2 (C400), and 700 g m-2 coir (C700) GTXs were first installed on a 9° slope under "no-infiltration" laboratory conditions, then on a 27° slope under natural field conditions. The impact of GTXs on run-off and soil loss was investigated to compare the performance of GTXs under different conditions. Laboratory run-off ratio (percentage portion of control plot) equalled 78, 83, and 91 %, while peak discharge ratio equalled 83, 91, and 97 % for J500, C700, and C400 respectively. In the field, a run-off ratio of 31, 62, and 79 %, and peak discharge ratio of 37, 74, and 87 % were recorded for C700, J500, and C400 respectively. All tested GTXs significantly decreased soil erosion. The greatest soil loss reduction in the field was observed for J500 (by 99.4 %), followed by C700 (by 97.9 %) and C400 (by 93.8 %). Irrespective of slope gradient or experimental condition, C400 performed with lower run-off and peak discharge reduction than J500 and C700. The performance ranking of J500 and C700 in the laboratory differed from the field, which may be explained by different slope gradients, and also by the role of soil, which was not included in the laboratory experiment.

  4. Four experimental demonstrations of active vibration control for flexible structures

    Science.gov (United States)

    Phillips, Doug; Collins, Emmanuel G., Jr.

    1990-01-01

    Laboratory experiments designed to test prototype active-vibration-control systems under development for future flexible space structures are described, summarizing previously reported results. The control-synthesis technique employed for all four experiments was the maximum-entropy optimal-projection (MEOP) method (Bernstein and Hyland, 1988). Consideration is given to: (1) a pendulum experiment on large-amplitude LF dynamics; (2) a plate experiment on broadband vibration suppression in a two-dimensional structure; (3) a multiple-hexagon experiment combining the factors studied in (1) and (2) to simulate the complexity of a large space structure; and (4) the NASA Marshall ACES experiment on a lightweight deployable 45-foot beam. Extensive diagrams, drawings, graphs, and photographs are included. The results are shown to validate the MEOP design approach, demonstrating that good performance is achievable using relatively simple low-order decentralized controllers.

  5. Factors controlling erosion/deposition phenomena related to lahars at Volcán de Colima, Mexico

    Science.gov (United States)

    Vázquez, Rosario; Capra, Lucia; Coviello, Velio

    2016-08-01

    One of the most common phenomena at Volcán de Colima is the annual development of lahars that runs mainly through the southern ravines of the edifice. Since 2011 the study and the monitoring of these flows and of the associated rainfall has been achieved by means of an instrumented station located along the Montegrande ravine, together with the systematic surveying of cross-topographic profiles of the main channel. From these, we present the comparison of the morphological changes experimented by this ravine during the 2013, 2014 and 2015 rainy seasons. The erosion/deposition effects of 11 lahars that occurred during this period of time were quantified by means of the topographic profiles taken at the beginning and at the end of the rainy seasons and before and after the major lahar event of 11 June 2013. We identified (i) an erosive zone between 2100 and 1950 m a.s.l., 8° in slope, with an annual erosional rate of 10.3 % mainly due to the narrowness of the channel and to its high slope angle and (ii) an erosive-depositional zone, between 1900 and 1700 m a.s.l., ( ˜ 8 % erosion and ˜ 16 % deposition), characterized by a wider channel that decreases in slope angle (4°). Based on these observations, the major factors controlling the erosion/deposition rates in the Montegrande ravine are the morphology of the gully (i.e., channel bed slope and the cross section width) and the joint effect of sediment availability and accumulated rainfall. On the distal reach of the ravine, the erosion/deposition processes tend to be promoted preferentially one over the other, mostly depending on the width of the active channel. Only for extraordinary rainfall events are the largest lahars mostly erosive all along the ravine up to the distal fan where the deposition takes place. In addition, as well as the morphological characteristics of the ravine, the flow depth is a critical factor in controlling erosion, as deeper flows will promote erosion against deposition. Finally, by

  6. Soil conservation policy measures to control wind erosion in northwestern Europe

    NARCIS (Netherlands)

    Riksen, M.J.P.M.; Brouwer, F.M.; Graaff, de J.

    2003-01-01

    Wind erosion is not as significant or a widespread problem in Europe as in dryer parts of the world, but it can cause major damage in small areas. The hazard is greatest in the lowlands of northwestern Europe with more than 3 million ha at high-potential wind erosion risk. Crop damage and off-site d

  7. Impacts of terracing on soil erosion control and crop yield in two agro-ecological zones of Rwanda

    Science.gov (United States)

    Rutebuka, Jules; Ryken, Nick; Uwimanzi, Aline; Nkundwakazi, Olive; Verdoodt, Ann

    2017-04-01

    Soil erosion remains a serious limiting factor to the agricultural production in Rwanda. Terracing has been widely adopted in many parts of the country in the past years, but its effectiveness is not yet known. Besides the standard radical (bench) terraces promoted by the government, also progressive terraces (with living hedges) become adopted mainly by the farmers. The aim of this study was to measure short-term (two consecutive rainy seasons 2016A and 2016B) run-off and soil losses for existing radical (RT) and progressive (PT) terraces versus non-protected (NP) fields using erosion plots installed in two agro-ecological zones, i.e. Buberuka highlands (site Tangata) and Eastern plateau (site Murehe) and determine their impacts on soil fertility and crop production. The erosion plot experiment started with a topsoil fertility assessment and during the experiment, maize was grown as farmer's cropping preference in the area. Runoff data were captured after each rainfall event and the collected water samples were dried to determine soil loss. Both erosion control measures reduced soil losses in Tangata, with effectiveness indices ranging from 43 to 100% when compared to the NP plots. RT showed the highest effectiveness, especially in season A. In Murehe, RT minimized runoff and soil losses in both seasons. Yet, the PT were largely inefficient, leading to soil losses exceeding those on the NP plots (ineffectiveness index of -78% and -65% in season A and B, respectively). Though topsoil fertility assessment in the erosion plots showed that the soil quality parameters were significantly higher in RT and NP plots compared to the PT plots on both sites, maize grain yield was not correlated with the physical effectiveness of the erosion control measures. Finally, the effectiveness of soil erosion control measures as well as their positive impacts on soil fertility and production differ not only by terracing type but also by agro-ecological zone and the management or

  8. Interdisciplinary on-site evaluation of stone bunds to control soil erosion on cropland in Northern Ethiopia

    DEFF Research Database (Denmark)

    Nyssen, Jan; Poesen, Jean; Gebremichael, Desta

    2007-01-01

    Since two decades, stone bunds have been installed in large areas of the Tigray Highlands, Northern Ethiopia, to control soil erosion by water. Field studies were conducted to quantify the effectiveness, efficiency, side effects and acceptance of stone bunds. Based on measurements on 202 field pa...

  9. Erosion of soil organic carbon: implications for carbon sequestration

    Science.gov (United States)

    Van Oost, Kristof; Van Hemelryck, Hendrik; Harden, Jennifer W.; McPherson, B.J.; Sundquist, E.T.

    2009-01-01

    Agricultural activities have substantially increased rates of soil erosion and deposition, and these processes have a significant impact on carbon (C) mineralization and burial. Here, we present a synthesis of erosion effects on carbon dynamics and discuss the implications of soil erosion for carbon sequestration strategies. We demonstrate that for a range of data-based parameters from the literature, soil erosion results in increased C storage onto land, an effect that is heterogeneous on the landscape and is variable on various timescales. We argue that the magnitude of the erosion term and soil carbon residence time, both strongly influenced by soil management, largely control the strength of the erosion-induced sink. In order to evaluate fully the effects of soil management strategies that promote carbon sequestration, a full carbon account must be made that considers the impact of erosion-enhanced disequilibrium between carbon inputs and decomposition, including effects on net primary productivity and decomposition rates.

  10. Climate modulated erosion and sediment flux control offshore crustal structure at South China Sea continental margin

    Science.gov (United States)

    Clift, P. D.; Brune, S.; Quinteros, J.

    2015-12-01

    Rifted continental lithosphere subsides as a consequence of combined crustal thinning and mantle lithosphere cooling yet basins on some continental margins experience anomalous subsidence events that postdate active extension. Deep basins on the northern margin of the South China Sea, notably the Baiyun Sag, show basement subsidence accelerating after ~21 Ma, postdating extension by several million years. Similar subsidence events are seen after 5 Ma in the Song Hong Basin and after 11 Ma in the Qiongdongnan Basin. We combine geophysical observations and numerical forward modeling to show that loading of the offshore basins by increased sediment flux caused by faster onshore erosion following Early Miocene monsoon intensification is a viable trigger for ductile flow after the cessation of active extension. Loading works in conjunction with onshore uplift to drive flow of the lower crust away from the rift axis. As well as sediment supply rates distribution patterns and drainage capture can be significant in controlling crustal flow and thinning. This illustrates that offshore basin dynamics at continental margins with weak crust can be controlled by onshore surface processes in a newly recognized form of climate-tectonic coupling.

  11. TILLAGE EROSION: THE PRINCIPLES, CONTROLLING FACTORS AND MAIN IMPLICATIONS FOR FUTURE RESEARCH

    Directory of Open Access Journals (Sweden)

    Agnieszka Wysocka-Czubaszek

    2014-10-01

    Full Text Available Tillage erosion is one of the major contributors to landscape evolution in hummocky agricultural landscapes. This paper summarizes the available data describing tillage erosion caused by hand-held or other simple tillage implements as well as tools used in typical conventional agriculture in Europe and North America. Variations in equipment, tillage speed, depth and direction result in a wide range of soil translocation rates observed all over the world. The variety of tracers both physical and chemical gives a challenge to introduce the reliable model predicting tillage erosion, considering the number and type of tillage operation in the whole tillage sequence.

  12. Dynamic controls on erosion and deposition on debris-flow fans.

    OpenAIRE

    Schürch, P.; Densmore, A. L.; Rosser, N.J.; B. W. McArdell

    2011-01-01

    Debris flows are among the most hazardous and unpredictable of surface processes in mountainous areas. This is partly because debris-flow erosion and deposition are poorly understood, resulting in major uncertainties in flow behavior, channel stability, and sequential effects of multiple flows. Here we apply terrestrial laser scanning and flow hydrograph analysis to quantify erosion and deposition in a series of debris flows at Illgraben, Switzerland. We identify flow depth as an important co...

  13. Erosion-corrosion; Erosionkorrosion

    Energy Technology Data Exchange (ETDEWEB)

    Aghili, B

    1999-05-01

    A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment 32 refs, 16 figs, tabs

  14. Deglaciation and glacial erosion: a joint control on magma productivity by continental unloading

    Science.gov (United States)

    Sternai, Pietro; Caricchi, Luca; Castelltort, Sebastien

    2016-04-01

    Glacial-interglacial cycles affect the processes through which water and rocks are redistributed across the Earth's surface, thereby linking solid-Earth and climate dynamics. Regional and global scale studies suggest that continental lithospheric unloading due to ice melting during the transition to interglacials leads to increased continental magmatic, volcanic and degassing activity. Such a climatic forcing on the melting of the Earth's interior, however, has always been evaluated without considering the additional continental unloading associated with erosion. Current datasets relating to the evolution of erosion rates are typically limited by temporal resolutions that are too low or span too short time intervals to allow for direct comparisons between the contributions from ice melting and erosion to continental unloading at the timescale of the late Pleistocene glacial cycles. Yet, they provide a fundamental observational basis on which to calibrate numerical predictions. Here, we present and discuss numerical results involving synthetic but realistic topographies, ice caps and glacial erosion rates suggesting that erosion may be as important as deglaciation in affecting continental unloading, sub-continental decompression melting and magma productivity. Thus, the timing and magnitude of deglaciation and erosion must be characterized if the forcing of climate change on the continental magmatic/volcanic activity is to be extracted from the remnants of eroded volcanic centers. Our study represents an additional step towards a more general understanding of the links between a changing climate, glacial processes and the melting of the solid Earth.

  15. Effects of aridity in controlling the magnitude of runoff and erosion after wildfire

    Science.gov (United States)

    Noske, Philip J.; Nyman, Petter; Lane, Patrick N. J.; Sheridan, Gary J.

    2016-06-01

    This study represents a uniquely high-resolution observation of postwildfire runoff and erosion from dry forested uplands of SE Australia. We monitored runoff and sediment load, and temporal changes in soil surface properties from two (0.2-0.3 ha) dry forested catchments burned during the 2009 Black Saturday wildfire. Event-based surface runoff to rainfall ratios approached 0.45 during the first year postwildfire, compared to reported values forests were attributed to wildfire-induced soil water repellency and inherently low hydraulic conductivity. Mean ponded hydraulic conductivity ranged from 3 to 29 mm h-1, much lower than values commonly reported for wetter forest. Annual sediment yields peaked at 10 t ha-1 during the first year before declining dramatically to background levels, suggesting high-magnitude erosion processes may become limited by sediment availability on hillslopes. Small differences in aridity between equatorial and polar-facing catchments produced substantial differences in surface runoff and erosion, most likely due to higher infiltration and surface roughness on polar-facing slopes. In summary, the results show that postwildfire erosion processes in Eucalypt forests in south-east Australia are highly variable and that distinctive response domains within the region exist between different forest types, therefore regional generalizations are problematic. The large differences in erosion processes with relatively small changes in aridity have large implications for predicting hydrologic-driven geomorphic changes, land degradation, and water contamination through erosion after wildfire across the landscape.

  16. Holocene Fire, Climate and Erosion in the Jemez Mountains, New Mexico: Natural and Anthropogenic Controls

    Science.gov (United States)

    Meyer, G. A.; Fitch, E. P.

    2013-12-01

    Ponderosa pine and mixed-conifer forests in the Jemez Mountains have been ravaged by extensive severe fires in the last two decades, which burned almost 1000 km2, roughly 30% of this middle-elevation range. Tree-ring fire history reconstructions indicate that a low-severity fire regime characterized the ca. 400 years before Euroamerican settlement, and that fuel buildup from fire suppression and land-use impacts contributed to increased fire severity in recent years. In order to better understand natural variability, climatic influences, and erosional effects of wildfire activity since ~5000 cal yr BP, we identified and 14C-dated fire-related alluvial deposits in the 2002 Lakes Fire area in the southwestern Jemez Mountains. These deposits indicate that most late Holocene fire-related erosional events were relatively minor, consistent with the low-severity burns that dominate the tree-ring record, but larger debris flows also occurred, suggesting at least small areas of high-severity fire. Although changes in postfire sedimentation are not so clearly related to millennial-scale Holocene climatic changes as in the Northern Rocky Mountains, peaks in fire-event probability correspond with severe regional multidecadal droughts ca. 1800 and 375 cal yr BP. Local microclimatic controls on vegetation, soils, and post-fire sedimentation are also evident. Relatively dense mixed-conifer stands including Douglas-fir typify moister north-facing basins, where soils are apparently thicker and more permeable than on southerly aspects. Alluvial fans of these basins are dominated by fire-related deposits (77% of measured stratigraphic thickness), thus we interpret that little erosion occurs in the absence of wildfires. Holocene fire-related events from north slopes are also of somewhat lower frequency, and possibly of higher severity. In contrast, in ponderosa pine-dominated south-facing basins, fire-related deposits make up only 39% of measured fan deposits. On drier south aspects

  17. Experimental demonstration of a controllable electrostatic molecular beam splitter.

    Science.gov (United States)

    Deng, Lianzhong; Liang, Yan; Gu, Zhenxing; Hou, Shunyong; Li, Shengqiang; Xia, Yong; Yin, Jianping

    2011-04-01

    We experimentally demonstrate a controllable electrostatic beam splitter for guided ND3 molecules with a single Y-shaped charged wire and a homogeneous bias field generated by a charged metallic parallel-plate capacitor. We study the dependences of the splitting ratio R of the guided ND3 beam and its relative guiding efficiency η on the voltage difference between two output arms of the splitter. The influences of the molecular velocity v and the cutting position L on the splitting ratio R are investigated as well, and the guiding and splitting dynamic processes of cold molecules are simulated. Our study shows that the splitting ratio R of our splitter can be conveniently adjusted from 10% to 90% by changing ΔU from -6  kV to +6  kV, and the simulated results are consistent with our experimental ones.

  18. Micronized Coal Reburning Demonstration for NOx Control: A DOE Assessment

    Energy Technology Data Exchange (ETDEWEB)

    National Energy Technology Laboratory

    2001-08-15

    The goal of the U.S. Department of Energy's (DOE) Clean Coal Technology (CCT) program is to furnish the energy marketplace with a number of advanced, more efficient, and environmentally responsible coal utilization technologies through demonstration projects. These projects seek to establish the commercial feasibility of the most promising advanced coal technologies that have developed beyond the proof-of-concept stage. This document serves as a DOE post-project assessment of a project selected in CCT Round IV, the Micronized Coal Reburning (MCR) Demonstration for NO{sub x} Control, as described in a report to Congress (U.S. Department of Energy 1999). The need to meet strict emissions requirements at a minimum cost prompted the Tennessee Valley Authority (TVA), in conjunction with Fuller Company, Energy and Environmental Research Corporation (EER), and Fluor Daniel, to submit the proposal for this project to be sited at TVA's Shawnee Fossil Plant. In July 1992, TVA entered into a cooperative agreement with DOE to conduct the study. However, because of operational and environmental compliance strategy changes, the Shawnee site became unavailable.

  19. Pushing the Limits of Cubesat Attitude Control: A Ground Demonstration

    Science.gov (United States)

    Sanders, Devon S.; Heater, Daniel L.; Peeples, Steven R.; Sules. James K.; Huang, Po-Hao Adam

    2013-01-01

    A cubesat attitude control system (ACS) was designed at the NASA Marshall Space Flight Center (MSFC) to provide sub-degree pointing capabilities using low cost, COTS attitude sensors, COTS miniature reaction wheels, and a developmental micro-propulsion system. The ACS sensors and actuators were integrated onto a 3D-printed plastic 3U cubesat breadboard (10 cm x 10 cm x 30 cm) with a custom designed instrument board and typical cubesat COTS hardware for the electrical, power, and data handling and processing systems. In addition to the cubesat development, a low-cost air bearing was designed and 3D printed in order to float the cubesat in the test environment. Systems integration and verification were performed at the MSFC Small Projects Rapid Integration & Test Environment laboratory. Using a combination of both the miniature reaction wheels and the micro-propulsion system, the open and closed loop control capabilities of the ACS were tested in the Flight Robotics Laboratory. The testing demonstrated the desired sub-degree pointing capability of the ACS and also revealed the challenges of creating a relevant environment for development testin

  20. Controlled Impact Demonstration instrumented test dummies installed in plane

    Science.gov (United States)

    1984-01-01

    In this photograph are seen some of dummies in the passenger cabin of the B-720 aircraft. NASA Langley Research Center instrumented a large portion of the aircraft and the dummies for loads in a crashworthiness research program. In 1984 NASA Dryden Flight Research Facility and the Federal Aviation Adimistration (FAA) teamed-up in a unique flight experiment called the Controlled Impact Demonstration (CID). The test involved crashing a Boeing 720 aircraft with four JT3C-7 engines burning a mixture of standard fuel with an additive called Anti-misting Kerosene (AMK) designed to supress fire. In a typical aircraft crash, fuel spilled from ruptured fuel tanks forms a fine mist that can be ignited by a number of sources at the crash site. In 1984 the NASA Dryden Flight Research Facility (after 1994 a full-fledged Center again) and the Federal Aviation Administration (FAA) teamed-up in a unique flight experiment called the Controlled Impact Demonstration (CID), to test crash a Boeing 720 aircraft using standard fuel with an additive designed to supress fire. The additive, FM-9, a high-molecular-weight long-chain polymer, when blended with Jet-A fuel had demonstrated the capability to inhibit ignition and flame propagation of the released fuel in simulated crash tests. This anti-misting kerosene (AMK) cannot be introduced directly into a gas turbine engine due to several possible problems such as clogging of filters. The AMK must be restored to almost Jet-A before being introduced into the engine for burning. This restoration is called 'degradation' and was accomplished on the B-720 using a device called a 'degrader.' Each of the four Pratt & Whitney JT3C-7 engines had a 'degrader' built and installed by General Electric (GE) to break down and return the AMK to near Jet-A quality. In addition to the AMK research the NASA Langley Research Center was involved in a structural loads measurement experiment, which included having instrumented dummies filling the seats in the

  1. INNOVATIVE IN-SITU REMEDIATION OF CONTAMINATED SEDIMENTS FOR SIMULTANEOUS CONTROL OF CONTAMINATION AND EROSION

    Energy Technology Data Exchange (ETDEWEB)

    Knox, A; Michael Paller, M; Danny D. Reible, D; Ioana G. Petrisor, I

    2007-11-28

    organoclays have high potential for controlling organic contaminants. Measured partitioning coefficients were used to model the time required for a contaminant to penetrate sediment caps composed of organoclay. The results showed that a thin layer of highly sorptive organoclay can lead to very long migration times, perhaps longer than the expected lifetime of the contaminant in the sediment environment. A one-dimensional numerical model was used to examine the diffusion of metals through several cap material based on measured and assumed material and transport properties. These studies showed that active caps composed of apatite or organoclay have the potential to delay contaminant breakthrough due to diffusion by hundreds of years or more compared with passive caps composed of sand. Advectively dominated column experiments are currently underway to define effective sorption related retardation factors in promising amendments for various hydrophobic organic compounds. Upon completion of these experiments, advection transient models will be used to estimate the time required for the breakthrough of various contaminants in caps composed of different experimental materials. Biopolymer products for inclusion in active caps were evaluated on the basis of resistance to biodegradation, sorption capacity for organic and inorganic contaminants, and potential for erosion control. More than 20 biopolymer products were evaluated resulting in the selection of chitosan/guar gum cross-linked with borax and xanthan/chitosan cross-linked with calcium chloride for inclusion in active caps to produce a barrier that resists mechanical disturbance. A process was developed for coating sand with cross-linked biopolymers to provide a means for delivery to the sediment surface. Properties of biopolymer coated sand such as carbon fraction (indicating biopolymer coverage), porosity, bulk density, and biodegradability have been evaluated, and experiments are currently underway to assess the resistance

  2. Wind power stabilising control. Demonstration on the Nordic grid

    Energy Technology Data Exchange (ETDEWEB)

    Elkington, Katherine

    2012-07-01

    When unconventional types of generators such as doubly fed induction generators (DFIGs) are used in a power system, the system behaves differently under abnormal dynamic events. For example, DFIGs cause different modes of oscillation in the power system, and respond differently to changes in voltage. In order to damp oscillations in the system, it is necessary to understand the equipment causing these oscillations, and the methods of optimally damping the oscillations. Large power oscillations can occur in a power system as a result of disturbances. Ordinarily these oscillations are slow and, in principle, it is possible to damp them with the help of wind power. This suggests the use of a power oscillation damping (POD) controller for a DFIG, similar to a power system stabiliser (PSS) for a synchronous generator. Voltage stability is another important aspect of the safe operation of a power system. It has been shown that the voltage stability of a power system is affected by induction generators and also DFIGs, and we investigate some aspects of this here. In this study we develop control strategies for large wind farms comprising DFIGs, and study the impact of the wind farms on a system which is designed to reflect the dynamics of the Nordic power system. The design of multiple PODs in a wind farm is undertaken using linear matrix inequalities (LMIs). The impact of the wind turbines is investigated through the use of linear and dynamic simulations. It has been demonstrated that DFIG-based wind farms can be used for damping oscillations, even when they are not producing their rated power, and that they can also improve the critical clearing time of some faults. However, they may have an adverse impact on power systems after large voltage disturbances

  3. Thermal Performance of ATLAS Laser Thermal Control System Demonstration Unit

    Science.gov (United States)

    Ku, Jentung; Robinson, Franklin; Patel, Deepak; Ottenstein, Laura

    2013-01-01

    than 135 watts of heater power. 4) The LHP reservoir control heater power is limited to 15 watts with a 70 percent duty cycle. 5) The voltage of the power supply can vary between 26 volts direct current and 34 volts direct current during the spacecraft lifetime. A design analysis shows that a single LTCS can satisfy these requirements. However, shutdown of· the LHP is particularly challenging and the shutdown heater must be wired in series with two reservoir thermostats and two CCHP thermostats at different set points. An LTCS demonstration unit has been tested to verify these performance characteristics experimentally prior to proceeding to the final LTCS design and fabrication. Test results showed that the LHP shutdown scheme would be able to shut down the LHP as designed and the reservoir control heater can maintain the ATLAS mass simulator within the plus or minus 1 degrees Centigrade accuracy under various combinations of the heat load, sink temperature, and power supply voltage.

  4. Barrier erosion control test plan: Gravel mulch, vegetation, and soil water interactions

    Energy Technology Data Exchange (ETDEWEB)

    Waugh, W.J.; Link, S.O. (Pacific Northwest Lab., Richland, WA (USA))

    1988-07-01

    Soil erosion could reduce the water storage capacity of barriers that have been proposed for the disposal of near-surface waste at the US Department of Energy's Hanford Site. Gravel mixed into the top soil surface may create a self-healing veneer that greatly retards soil loss. However, gravel admixtures may also enhance infiltration of rainwater, suppress plant growth and water extraction, and lead to the leaching of underlying waste. This report describes plans for two experiments that were designed to test hypotheses concerning the interactive effects of surface gravel admixtures, revegetation, and enhanced precipitation on soil water balance and plant abundance. The first experiment is a factorial field plot set up on the site selected as a soil borrow area for the eventual construction of barriers. The treatments, arranged in a a split-split-plot design structure, include two densities of gravel admix, a mixture of native and introduced grasses, and irrigation to simulate a wetter climate. Changes in soil water storage and plant cover are monitored with neutron moisture probes and point intercept sampling, respectively. The second experiment consists of an array of 80 lysimeters containing several different barrier prototypes. Surface treatments are similar to the field-plot experiment. Drainage is collected from a valve at the base of each lysimeter tube, and evapotranspiration is estimated by subtraction. The lysimeters are also designed to be coupled to a whole-plant gas exchange system that will be used to conduct controlled experiments on evapotranspiration for modeling purposes. 56 refs., 6 figs., 8 tabs.

  5. Effectiveness of the GAEC standard of cross compliance retain terraces on soil erosion control

    Directory of Open Access Journals (Sweden)

    Paolo Bazzoffi

    2011-08-01

    Full Text Available The GAEC standard retain terraces of cross compliance prohibits farmers the elimination of existing terraces, with the aim to ensure the protection of soil from erosion. In the Italian literature there are not field studies to quantify the effects of the elimination or degradation of terraces on soil erosion. Therefore, the modeling approach was chosen and applied in a scenario analysis to evaluate increasing levels of degradation of stone wall terraces. The study was conducted on two sample areas: Lamole (700.8 ha, Tuscany and Costaviola (764.73 ha, Calabria with contrasting landscapes. The Universal Soil Loss Equation model (USLE was applied in the comparative assessment of the soil erosion risk (Mg . ha-1 . yr-1, by simulating five increasing intensity of terrace degradation, respectively: conserved partially damaged, very damaged, partially removed, removed, each of which corresponding to different values of the indexes of verification in case of infringement to GAEC standard provided for by the AGEA rules which have come into force since December 2009 (Agency for Agricultural Payments. To growing intensity of degradation, a progressive loss of efficacy of terraces was attributed by increasing the values of the LS factor (length and slope of USLE in relation with the local modification of the length and steepness of the slope between adjacent terraces. Basically, it was simulated the gradual return to the natural morphology of the slope. The results of the analysis showed a significant increase in erosion in relationship with increasing degradation of terraces. Furthermore, it is possible to conclude that the GAEC standard retain terraces is very effective with regard to the primary objective of reducing erosion. A further statistical analysis was performed to test the protective value of terraces against soil erosion in areas where agriculture was abandoned. The analysis was carried out by comparing the specific risk of erosion (Mg . ha-1

  6. Watershed management for erosion and sedimentation control Case Study: Goodwin Creek, Panola County, MS

    Science.gov (United States)

    The Goodwin Creek watershed is located within the loessal hills of northern Mississippi, a region of high erosion risk and elevated watershed sediment yields. This manuscript combines a regional history of land management and conservation issues from the time of European settlement to present with a...

  7. Controlling Gully Erosion: An Analysis of Land Reclamation Processes and Challenges in Chambal Badlands, India

    Science.gov (United States)

    Pani, Padmini

    2016-04-01

    Gully erosion is among the significant environmental problems in the Central Indian states. The Chambal badlands, spread over an area of around 4000 sq. kms is among the worst affected regions in terms of land degradation. The enormity of the Chambal ravines, which achieve depths of more than 60 metres, points to the significance of the geological explanation, suggesting that neotectonics may have paved the way for ravine erosion, but it is most definitely exacerbated by anthropogenic activities. Although, there is field evidence that ephemeral gully erosion is responsible for significant soil losses, little is known about the contributing factors. The region also faces significant developmental challenges and the inaccessibility and low productivity of the area contributes to its continued underdevelopment. This study uses a combination of geo-spatial techniques and physical and socio-economic field survey to evaluate the responses to gully erosion and its implications. This paper attempts to study (a) extent and severity of gully erosion process in the Chambal badlands; (b) an evaluation of reclamation measures undertaken by various agencies, including the affected people; (c) to examine the sustainability implications of land reclamation measures. The extent, pattern and inter-temporal changes of gully erosion have been examined through various mapping techniques and field survey. The land reclamation have been mapped using satellite images and ground truth verification. The various kinds of land reclamation measures that have been undertaken on the ground and their sustainability implications have been investigated through survey of affected households in selected villages. The results show that in response to the severe loss of agricultural land because of gully head encroachment in the agricultural field and decline in land productivity, farmers have undertaken various land reclamation measures, including mechanised land levelling. The land levelling

  8. Novel Data Acquisition and controls System (DACS) Demonstration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The combined data acquisition and controls architecture is eliminating the need of the widely popular programmable logic control (PLCs).   The system uses...

  9. "Back fall" dust controls seasonal erosion and composition measurements of 67P

    Science.gov (United States)

    Keller, Horst Uwe; Hviid, Stubbe F.; Mottola, Stefano; Agarwal, Jessica; OSIRIS

    2016-10-01

    Seasonal effects of 67P's activity are very pronounced due to the strong insolation during southern summer when the comet is near its perihelion. About ¾ of the overall gas and dust production are released from the southern hemisphere when large parts of the surface near the north pole are in polar night (Keller et al. 2015). This leads to a dichotomy of the hemispheres. The southern regions show rough consolidated material whereas the northern plain surfaces are covered by what looks like dust (El Maary et al 2015). Recent close up observations of the northern territories show a granularity near the resolution limit of the images. This is comparable to the sizes of particles (10-20 cm) seen to cross the coma at velocities comparable to or below the escape speed from the nucleus around perihelion. These large particles are deprived from super volatiles but maintain their water ice content. A major part will cover the northern hemisphere as "back fall" over the aphelion passage and will lead to water controlled activity from the northern hemisphere during the next cometary approach. New dune-like features (Thomas et al. 2015) have been recently observed in the gravitational low Hapi region. Philae ROLIS images show wind tails and moats around obstacles, all oriented in a south-north direction, that are well modelled by abrasion by impinging back fall from the south (Mottola et al. 2015). Consequently activity from the northern hemisphere during the early Rosetta mission revealed mainly water molecules (Fougere et al. to be submitted) originating from back fall and not from the original consolidated surface, that was widely isolated by the cover of back fall. Hence more volatile compounds such as CO2 and CO are not reached by insolation. Composition measurements of the northern hemisphere are strongly influenced by the back fall cover and do not reflect the original composition of the nucleus. A further consequence is that erosion of the nucleus of 67P takes place

  10. Reactive power control with CHP plants - A demonstration

    DEFF Research Database (Denmark)

    Nyeng, Preben; Østergaard, Jacob; Andersen, Claus A.;

    2010-01-01

    power rating of 7.3 MW on two synchronous generators. A closed-loop control is implemented, that remote controls the CHP plant to achieve a certain reactive power flow in a near-by substation. The solution communicates with the grid operator’s existing SCADA system to obtain measurements from...

  11. Erosion Control and Recultivation Measures at a Headrace Channel of a Hydroelectric Power Plant using Different Combined Soil Bioengineering Techniques

    Science.gov (United States)

    Obriejetan, M.; Florineth, F.; Rauch, H. P.

    2012-04-01

    As a consequence of land use change resulting in an increased number of slope protection constructions and with respect to effects associated with climate change like extremes in temperatures and temperature variations or increased frequency of heavy precipitation, adaptation strategies for sustainable erosion protection systems are needed which meet ecological compatibility and economical requirements. Therefore a wide range of different technical solutions respectively geotextiles and geotextile-related products (blankets, nettings, grids etc.) are available on the market differing considerably in function, material, durability and pricing. Manufacturers usually provide product-specific information pertaining to application field, functional range or (technical) installation features whereas vegetational aspects are frequently neglected while vegetation can contribute substantially to increased near-surface erosion protection respectively slope stability. Though, the success of sustainable erosion control is directly dependent on several vegetational aspects. Adequate development of a functional vegetation layer in combination with geotextiles is closely associated to application aspects such as seeding technique, sowing date and intensity, seed-soil contact or maintenance measures as well as to qualitative aspects like seed quality, germination rates, area of origin, production method or certification. As a general guideline, erosion control within an initial phase is directly related to restoration techniques whereas vegetation specifics with regard to species richness or species composition play a key role in medium to long-term development and slope protection. In this context one of the fundamental objectives of our study is the identification and subsequently the determination of the main interaction processes between technical and biological components of combined slope protection systems. The influence of different geotextile characteristics on specific

  12. Monsoonal vs. glacial control on erosion and sediment storage in the Himalayan rain shadow, Zanskar River, northwest India

    Science.gov (United States)

    Jonell, Tara; Clift, Peter; Carter, Andrew; Böning, Philipp; Wittmann, Hella

    2016-04-01

    Summer monsoon precipitation strongly controls erosion and sediment storage in the frontal Himalaya but the relationship between monsoonal variability and erosion is less well-constrained beyond the High Himalayan topographic divide in the rain shadow. Here we establish a Quaternary erosional history for a rain shadow tributary of the upper Indus River system, the Zanskar River, by applying several sediment provenance techniques to modern and dated terrace river sediments. We evaluate if there are temporal links between sediment storage and moisture supply to the rain shadow and if regions like the Zanskar River basin play a significant role in controlling total sediment flux to the Indus River. We compile bulk sediment petrography and Sr and Nd isotope geochemistry, detrital U-Pb zircon and apatite fission track dating with in-situ 10Be cosmogenic radionuclide techniques to identify patterns of erosion and sediment production across Zanskar. Bulk petrography, Sr and Nd isotope geochemistry, and U-Pb detrital zircon spectra of modern and older terrace sediments indicate high rates of erosion along the Greater Himalaya in the Zanskar River basin. We find that the wettest and most glaciated subcatchment dominates the bulk sediment provenance signal, with only moderate input from other tributaries, and that other basin parameters cannot explain our observations. Catchment-averaged in-situ 10Be cosmogenic nuclide concentrations of modern sediments indicate erosion rates up to ˜1.2 mm y-1 but show strong dilution attributed to glacial sediment recycling into the modern river, suggesting rates nearer 0.4-0.6 mm•y-1. These rates are consistent with longer-term rates of incision (0.3-0.7 mm•y-1) calculated from detrital apatite fission track ages, and incision rates inferred from Late Glacial and Holocene terraces near the Zanskar-Indus confluence. Our findings suggest that sediment production in glaciated Himalayan rain shadow environments like Zanskar is largely

  13. INNOVATIVE IN-SITU REMEDIATION OF CONTAMINATED SEDIMENTS FOR SIMULTANEOUS CONTROL OF CONTAMINATION AND EROSION

    Energy Technology Data Exchange (ETDEWEB)

    Knox, A; Michael Paller, M; Danny D. Reible, D; Ioana G. Petrisor, I

    2007-11-28

    organoclays have high potential for controlling organic contaminants. Measured partitioning coefficients were used to model the time required for a contaminant to penetrate sediment caps composed of organoclay. The results showed that a thin layer of highly sorptive organoclay can lead to very long migration times, perhaps longer than the expected lifetime of the contaminant in the sediment environment. A one-dimensional numerical model was used to examine the diffusion of metals through several cap material based on measured and assumed material and transport properties. These studies showed that active caps composed of apatite or organoclay have the potential to delay contaminant breakthrough due to diffusion by hundreds of years or more compared with passive caps composed of sand. Advectively dominated column experiments are currently underway to define effective sorption related retardation factors in promising amendments for various hydrophobic organic compounds. Upon completion of these experiments, advection transient models will be used to estimate the time required for the breakthrough of various contaminants in caps composed of different experimental materials. Biopolymer products for inclusion in active caps were evaluated on the basis of resistance to biodegradation, sorption capacity for organic and inorganic contaminants, and potential for erosion control. More than 20 biopolymer products were evaluated resulting in the selection of chitosan/guar gum cross-linked with borax and xanthan/chitosan cross-linked with calcium chloride for inclusion in active caps to produce a barrier that resists mechanical disturbance. A process was developed for coating sand with cross-linked biopolymers to provide a means for delivery to the sediment surface. Properties of biopolymer coated sand such as carbon fraction (indicating biopolymer coverage), porosity, bulk density, and biodegradability have been evaluated, and experiments are currently underway to assess the resistance

  14. Erosion by an Alpine glacier.

    Science.gov (United States)

    Herman, Frédéric; Beyssac, Olivier; Brughelli, Mattia; Lane, Stuart N; Leprince, Sébastien; Adatte, Thierry; Lin, Jiao Y Y; Avouac, Jean-Philippe; Cox, Simon C

    2015-10-09

    Assessing the impact of glaciation on Earth's surface requires understanding glacial erosion processes. Developing erosion theories is challenging because of the complex nature of the erosion processes and the difficulty of examining the ice/bedrock interface of contemporary glaciers. We demonstrate that the glacial erosion rate is proportional to the ice-sliding velocity squared, by quantifying spatial variations in ice-sliding velocity and the erosion rate of a fast-flowing Alpine glacier. The nonlinear behavior implies a high erosion sensitivity to small variations in topographic slope and precipitation. A nonlinear rate law suggests that abrasion may dominate over other erosion processes in fast-flowing glaciers. It may also explain the wide range of observed glacial erosion rates and, in part, the impact of glaciation on mountainous landscapes during the past few million years. Copyright © 2015, American Association for the Advancement of Science.

  15. History of bioengineering techniques for erosion control in rivers in Western Europe.

    Science.gov (United States)

    Evette, Andre; Labonne, Sophie; Rey, Freddy; Liebault, Frederic; Jancke, Oliver; Girel, Jacky

    2009-06-01

    Living plants have been used for a very long time throughout the world in structures against soil erosion, as traces have been found dating back to the first century BC. Widely practiced in Western Europe during the eighteenth and nineteenth centuries, bioengineering was somewhat abandoned in the middle of the twentieth century, before seeing a resurgence in recent times. Based on an extensive bibliography, this article examines the different forms of bioengineering techniques used in the past to manage rivers and riverbanks, mainly in Europe. We compare techniques using living material according to their strength of protection against erosion. Many techniques are described, both singly and in combination, ranging from tree planting or sowing seeds on riverbanks to dams made of fascine or wattle fences. The recent appearance of new materials has led to the development of new techniques, associated with an evolution in the perception of riverbanks.

  16. Role of mechanical erosion in controlling the effusion rate of basaltic eruptions

    Science.gov (United States)

    Piombo, Antonello; Tallarico, Andrea; Dragoni, Michele

    2016-09-01

    In many basaltic eruptions, observations show that the effusion rate of magma has a typical dependence on time: the effusion rate curves show first a period of increasing and later a decreasing phase by a maximum value. We present a model to explain this behavior by the emptying of a magma reservoir through a vertical cylindrical conduit with elliptical cross section, coupled with the its widening due to mechanical erosion, produced by the magma flow. The model can reproduce the observed dependence on time of effusion rate in basaltic eruptions. Eruption duration and the maximum value of effusion rate depend on the size of magma chamber, on lava viscosity and strongly on erosion rate per unit traction.

  17. [Influence of three types of riparian vegetation on fluvial erosion control in Pantanos de Centla, Mexico].

    Science.gov (United States)

    Sepúlveda-Lozada, Alejandra; Geissen, Violette; Ochoa-Gaona, Susana; Jarquín-Sánchez, Aarón; de la Cruz, Simón Hernández; Capetillo, Edward; Zamora-Cornelio, Luis Felipe

    2009-12-01

    Wetlands constitute very important ecological areas. The aim of this study was to quantify the soil losses due to fluvial erosion from 2006 to 2008 in two riverbanks under three types of vegetal coverage dominated by Haematoxylum campechianum, Dalbergia brownei and Brachiaria mutica, in the Pantanos de Centla Biosphere Reserve, SE Mexico. The relationship between the texture, organic matter and pH of soils and soil losses was evaluated. We used erosion sticks to estimate soil losses in 18 plots (three plots per type, three vegetation types, two riverbanks). Soil loss decreased in this order: H. campechianum>B. mutica>D. brownei indicating that D. brownei scrubland has the most potential to retain soil. The higher erosive impact within H. campechianum sites can be related with the low density of these trees in the study areas, as well as the lack of association with other types of vegetation that could reinforce the rooting of the soil profile. Furthermore, soil losses in H. campechianum sites were dependent on soil texture. The soils under this type of vegetal coverage were mainly sandy, which are more vulnerable to the erosive action in comparison with fine textured soils or soils with higher clay content, like the ones found in D. brownei and B. mutica sites. Soil losses of 100 % in the second year (B. mutica plots) can be attributed to the distribution of roots in the upper soil layer and also to livestock management along riverbanks. This study recognizes the importance of D. brownei scrublands in riverbank soil retention. Nevertheless it is necessary to consider the role of an entire vegetal community in future research.

  18. Erosion Control of Scour during Construction; Report 2. Literature Survey of Theoretical, Experimental, and Prototype Investigations.

    Science.gov (United States)

    1980-08-01

    greater resistance to erosion of the smaller size particles is an indication of the significance of cohesion and adhesion forces. 20. Neill (1967...there is a com- plicated interaction. A lightweight concrete aggregate with specific 85 _ _iI r ... .. . . l...apparatus. The proper viscosity can be prepared by adding the proper quantities of asphaltic bitumen to a mixture of sand and filler. To avoid steam

  19. Demonstrating Hormonal Control of Vertebrate Adaptive Color Changes in Vitro.

    Science.gov (United States)

    Hadley, Mac E.; Younggren, Newell A.

    1980-01-01

    Presented is a short discussion of factors causing color changes in animals. Also described is an activity which may be used to demonstrate the response of amphibian skin to a melanophore stimulating hormone in high school or college biology classes. (PEB)

  20. Commercial versus synthesized polymers for soil erosion control and growth of Chinese cabbage.

    Science.gov (United States)

    Lee, Sang Soo; Chang, Scott X; Chang, Yoon-Young; Ok, Yong Sik

    2013-01-01

    Soil erosion leads to environmental degradation and reduces soil productivity. The use of anionic polyacrylamide (PAM) and synthesized biopolymer (BP) using lignin, corn starch, acrylamide, and acrylic acid were tested to evaluate soil erosion, water quality, and growth of Chinese cabbage (Brassica campestris L.). Each treatment of PAM and BP was applied at 200 kg ha(-1) to loamy sand soil and subjected to a slope of 36% with a 20 mm h(-1) simulated rainfall. Application of BP decreased soil pH compared to the untreated check (CK); however, the soil pH was not altered with PAM. The decrease in pH might most likely be due to availability of anionic sites to be protonated on soils having pH >6 and soil buffering capacity. Both PAM and BP applications may not induce eutrophication with stable levels of total contents of N and P. With PAM and BP, the average values of suspended soil (SS) and turbidity were reduced by up to 96.0 and 99.9%, respectively, compared to CK. Reduction of SS can be attributed to increasing soil stability and shear strength by clay flocculation. There was no toxicity effects resulting from germination tests and the dry weight was increased by 17.7% (vs. CK) when PAM and BP were applied. These results are attributed to increases in water retention and plant-available water. The use of polymeric soil amendments is an environmentally friendly way to mitigate soil erosion and nonpoint source pollution.

  1. Effect of chemical and mechanical weed control on cassava yield, soil quality and erosion under cassava cropping system

    Science.gov (United States)

    Islami, Titiek; Wisnubroto, Erwin; Utomo, Wani

    2016-04-01

    Three years field experiments were conducted to study the effect of chemical and mechanical weed control on soil quality and erosion under cassava cropping system. The experiment were conducted at University Brawijaya field experimental station, Jatikerto, Malang, Indonesia. The experiments were carried out from 2011 - 2014. The treatments consist of three cropping system (cassava mono culture; cassava + maize intercropping and cassava + peanut intercropping), and two weed control method (chemical and mechanical methods). The experimental result showed that the yield of cassava first year and second year did not influenced by weed control method and cropping system. However, the third year yield of cassava was influence by weed control method and cropping system. The cassava yield planted in cassava + maize intercropping system with chemical weed control methods was only 24 t/ha, which lower compared to other treatments, even with that of the same cropping system used mechanical weed control. The highest cassava yield in third year was obtained by cassava + peanuts cropping system with mechanical weed control method. After three years experiment, the soil of cassava monoculture system with chemical weed control method possessed the lowest soil organic matter, and soil aggregate stability. During three years of cropping soil erosion in chemical weed control method, especially on cassava monoculture, was higher compared to mechanical weed control method. The soil loss from chemical control method were 40 t/ha, 44 t/ha and 54 t/ha for the first, second and third year crop. The soil loss from mechanical weed control method for the same years was: 36 t/ha, 36 t/ha and 38 t/ha. Key words: herbicide, intercropping, soil organic matter, aggregate stability.

  2. Bank erosion events and processes in the Upper Severn basin

    Directory of Open Access Journals (Sweden)

    D. M. Lawler

    1997-01-01

    Full Text Available This paper examines river bank retreat rates, individual erosion events, and the processes that drive them in the Upper Severn basin, mid-Wales, UK. Traditional erosion pin networks were used to deliver information on patterns of downstream change in erosion rates. In addition, the novel automatic Photo-Electronic Erosion Pin (PEEP monitoring system was deployed to generate near-continuous data on the temporal distribution of bank erosion and accretion: this allowed focus on the magnitude and timing of individual erosional and depositional events in relation to specific flow episodes. Erosion dynamics data from throughout the Upper Severn basin are combined with detailed information on bank material properties and spatial change in channel hydraulics derived from direct field survey, to assess the relationships between flow properties and bank erosion rates. Results show that bank erosion rates generally increase downstream, but relate more strongly to discharge than to reach-mean shear stress, which peaks near the basin head. Downstream changes in erosion mechanisms and boundary materials, across the upland/lowland transition (especially the degree of development of composite bank material profiles, are especially significant. Examples of sequences of bank erosion events show how the PEEP system can (a quantify the impact of individual, rather than aggregated, forcing events, (b reveal the full complexity of bank response to given driving agents, including delayed erosion events, and (c establish hypotheses of process-control in bank erosion systems. These findings have important implications for the way in which bank erosion problems are researched and managed. The complex responses demonstrated have special significance for the way in which bank processes and channel-margin sediment injections should be handled in river dynamics models.

  3. DEMONSTRATION OF AN ATCA BASED RF CONTROL SYSTEM AT FLASH

    CERN Document Server

    Simrock, S N; Jezynski, T; Koprek, W; Butkowski, L; Jablonski, G W; Jalmuzna, W; Makowski, D R; Piotrowski, A; Czuba, K

    2009-01-01

    Future rf control systems will require simultaneous data acquisition of up to 100 fast ADC channels at sampling rates of around 100 MHz and real time signal processing within a few hundred nanoseconds. At the same time the standardization of Low-Level RF systems are common objectives for all laboratories for cost reduction, performance optimization and machine reliability. Also desirable are modularity and scalability of the design as well as compatibility with accelerator instrumentation needs including the control system. All these requirements can be fulfilled with the new telecommunication standard ATCA when adopted to the domain of instrumentation. We describe the architecture and design of an ATCA based LLRF system for the European XFEL. The operation of a prototype capable of controlling the vectorsum of 24-cavities and providing measurements of forward and reflected power are presented.

  4. Buried waste integrated demonstration human engineered control station. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1994-09-01

    This document describes the Human Engineered Control Station (HECS) project activities including the conceptual designs. The purpose of the HECS is to enhance the effectiveness and efficiency of remote retrieval by providing an integrated remote control station. The HECS integrates human capabilities, limitations, and expectations into the design to reduce the potential for human error, provides an easy system to learn and operate, provides an increased productivity, and reduces the ultimate investment in training. The overall HECS consists of the technology interface stations, supporting engineering aids, platform (trailer), communications network (broadband system), and collision avoidance system.

  5. Assessment of the role of bottomland hardwoods in sediment and erosion control

    Science.gov (United States)

    Molinas, A.; Auble, Gregor T.; Segelquist, C.A.; Ischinger, Lee S.

    1988-01-01

    Drainage and clearing of bottomland hardwoods have long been recognized by the U.S. Environmental Protection Agency (EPA) and the U.S. Fish and Wildlife Service (Service) as important impacts of Federal water projects in the lower Mississippi River Valley. More recently, the water quality impacts of such projects (e.g., increases in sediments, nutrients, and pesticides) have also become of concern. In 1984, in an effort to better define problems concerning wetland losses and water degradation, EPA initiated a cooperative project with the Western Energy and Land Use Team (now the National Ecology Research Center) of the Service. Three phases of the project were identified: 1. To collect existing literature and data; 2. To select, develop, and test the utility of methods to quantify the relationships between land use, cover types, soils, hydrology, and water quality (as represented by sediment); and 3. To apply selected methodologies to several sites within the Yazoo Basin of Mississippi to determine the, potential effectiveness of various management alternatives to reduce sediment yield, increase sediment deposition, and improve water quality. Methods development focused on linking a simulation of water and sediment movement to a computerized geographic information system. We had several objectives for the resulting model. We desired that it should: 1. Estimate the importance of bottomland and hardwoods as a cover type that performs the functions of erosion and sediment control, 2. Simulate effects of proportions of ' various cover types and their specific spatial configurations, 3. Be applicable to moderately large spatial areas with minimal site-specific calibration, 4. Simulate spatial patterns of sediment loss-gain over time, and 5. Represent both sediment detachment and transport. While it was recognized that impacts and management alternatives could be sorted roughly into landscape measures and channel measures, the decision was made to focus study efforts

  6. Limited climate control of the Chugach/St. Elias thrust wedge in southern Alaska demonstrated by orogenic widening during Pliocene to Quaternary climate change

    Science.gov (United States)

    Meigs, Andrew

    2014-05-01

    Critical taper wedge theory is the gold standard by which climate control of convergent orogenic belts is inferred. The theory predicts (and models reproduce) that an orogenic belt narrows if erosion increases in erosion in the face of a constant tectonic influx. Numerous papers now argue on the basis of thermochronologic data that the Chugach/ St. Elias Range (CSE) of southern Alaska narrowed as a direct response to Quaternary climate change because glaciers dominated erosion of the orogenic belt. The CSE formed in response to collision of a microplate with North America and is notable because glacial erosion has dominated the CSE for the past 5 to 6 Ma. An increase in sediment accumulation rates in the foreland basin over that time suggests that glacial erosion become more efficient. If correct, it is possible that glacial erosion outpaced rock influx thereby inducing a climatically controlled narrowing of the orogenic wedge during the Quaternary. Growth strata preserved within the wedge provide a test of that interpretation because they demonstrate the spatial and temporal pattern of deformation during the Pliocene to Quaternary climate transition. A thrust front established between 6 and 5 Ma jumped towards the foreland by 30 and 15 km at 1.8 and 0.25 Ma, respectively. Distributed deformation within the thrust belt accompanied the thrust front relocations. Continuous exhumation recorded by low-temperature thermochronometers occurred contemporaneously with the shortening, parallel the structural not the topographic grain, and ages become younger towards the foreland as well. Interpreted in terms of critical wedge theory, continuous distributed deformation reflects a sub-critical wedge taper resulting from the combined effects of persistent exhumation and incremental accretion and orogenic widening via thrust front jumps into the undeformed foreland. Taper angle varies according to published cross-sections and ranges from 3 to 9 degrees. If the wedge oscillated

  7. Development of MCESC software for selecting the best stormwater erosion and sediment control measure in Malaysian construction sites

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hadu, Ibrahiem Abdul Razak; Sidek, Lariyah Mohd [Civil Engineering Universiti Tenaga Nasional, Kajan, Selangor (Malaysia); Desa, Mohamed Nor Mohamed; Basri, Noor Ezlin Ahmad [Civil and Structural Engineering, Universiti Kebangsaan Malaysia, Bangi, Selangor (Malaysia)

    2012-07-01

    Malaysia located in a tropical region which is interested with a heavy rainfall through the whole seasons of the year. Construction stages usually associated with soil disturbing due to land clearing and grading activities, this combined with the tropical climate in Malaysia, will generate an enormous amount of soil to be eroded and then deposited into the adjacent water bodies. There are many kinds of mitigation measures used so as to reduce the impact of erosion and sedimentation that are generated due to the stormwater in construction sites. This paper aims to develop and apply Multi Criteria Analysis (MCA) software called Multi Criteria Erosion and Sediment Control (MCESC) software in which it can be applied in selecting the best stormwater control measure by depending on specified criteria and criterion weight. Visual Basic 6 was adopted as a development tool. This software can help the engineers, contractors on site and decision makers to find the best stormwater control measure in any construction site in Malaysia. Users of the MCESC software are given the opportunity to select the best stormwater control measure via expert's judgments that are built in the system or via their own expertise. MCESC software has many benefits since the experts are not always available and the consultancy is a costly issue which add further financial allocations to the project.

  8. Plasticity of motor control systems demonstrated by yoga training.

    Science.gov (United States)

    Telles, S; Hanumanthaiah, B H; Nagarathna, R; Nagendra, H R

    1994-04-01

    The static motor performance was tested in two groups with 20 subjects in each (age range 17 to 22 years, and 5 females in each group). Tests were carried out at the beginning and end of a 10 day period. The test required being able to insert and hold a metal stylus within holes of varying sizes for 15 sec. Accidental contacts between the stylus and the sides of the holes, were registered on a counter as errors. During the 10 days one group (the yoga group) practised asanas (physical postures), pranayama (voluntary regulation of breathing), meditation, devotional sessions, and tratakas (visual focussing exercises). The control group followed their usual routine. At the end of 10 days the yoga group showed a significant reduction in number of errors (Wilcoxon paired signed ranks test), while the control group did not change. Our earlier study showed a similar improvement in children (9-13 years). It was interesting to note the same degree of plasticity in motor control systems in young adults. The implications for rehabilitation programmes have been discussed.

  9. Investigation of wind erosion process for estimation, prevention, and control of DSS in Yazd-Ardakan plain.

    Science.gov (United States)

    Ekhtesasi, M R; Sepehr, A

    2009-12-01

    accidents on the main roads of Yazd-Ardakan and can cancel the airplane flights in the stormy days. At present, it is estimated that wind erosion causes more than $6.8 million damages to socioeconomic resources in Yazd plain each year. This paper describes the pattern of occurrence of wind erosion and major contributing factors, summarizes measured rates of wind erosion, outlines the techniques used to mitigate wind erosion hazard, and suggests research priorities. Also, damages of DSS have been estimated and methods for prevention and control are suggested.

  10. Polyanhydride degradation and erosion.

    Science.gov (United States)

    Göpferich, A; Tessmar, J

    2002-10-16

    It was the intention of this paper to give a survey on the degradation and erosion of polyanhydrides. Due to the multitude of polymers that have been synthesized in this class of material in recent years, it was not possible to discuss all polyanhydrides that have gained in significance based on their application. It was rather the intention to provide a broad picture on polyanhydride degradation and erosion based on the knowledge that we have from those polymers that have been intensively investigated. To reach this goal this review contains several sections. First, the foundation for an understanding of the nomenclature are laid by defining degradation and erosion which was deemed necessary because many different definitions exist in the current literature. Next, the properties of major classes of anhydrides are reviewed and the impact of geometry on degradation and erosion is discussed. A complicated issue is the control of drug release from degradable polymers. Therefore, the aspect of erosion-controlled release and drug stability inside polyanhydrides are discussed. Towards the end of the paper models are briefly reviewed that describe the erosion of polyanhydrides. Empirical models as well as Monte-Carlo-based approaches are described. Finally it is outlined how theoretical models can help to answer the question why polyanhydrides are surface eroding. A look at the microstructure and the results from these models lead to the conclusion that polyanhydrides are surface eroding due to their fast degradation. However they switch to bulk erosion once the device dimensions drop below a critical limit.

  11. Demand as Frequency Controlled Reserve: Implementation and practical demonstration

    DEFF Research Database (Denmark)

    Douglass, Philip James; Garcia-Valle, Rodrigo; Nyeng, Preben

    2011-01-01

    One of the challenges in electric power systems with a high penetration of renewable generation is the provision of ancillary services. Traditionally these services have been provided by conventional generation, but as power from renewable sources (wind and PV) displaces conventional generation......, new providers of ancillary services are needed. Frequency regulation is critical because fluctuating energy sources increase the need for this service. At very high levels of renewable penetration, all available frequency regulation services will be called on, including demand-side resources. Electric...... loads that provide thermal energy services are attractive because their heat capacity allows electric power consumption to be moved in time without degrading the quality of service. This concept is being demonstrated in field tests on the island of Bornholm, Denmark....

  12. Demand as Frequency Controlled Reserve: Implementation and practical demonstration

    DEFF Research Database (Denmark)

    Douglass, Philip James; Garcia-Valle, Rodrigo; Nyeng, Preben;

    2011-01-01

    , new providers of ancillary services are needed. Frequency regulation is critical because fluctuating energy sources increase the need for this service. At very high levels of renewable penetration, all available frequency regulation services will be called on, including demand-side resources. Electric......One of the challenges in electric power systems with a high penetration of renewable generation is the provision of ancillary services. Traditionally these services have been provided by conventional generation, but as power from renewable sources (wind and PV) displaces conventional generation...... loads that provide thermal energy services are attractive because their heat capacity allows electric power consumption to be moved in time without degrading the quality of service. This concept is being demonstrated in field tests on the island of Bornholm, Denmark....

  13. Ecosystem-controlled Erosion in a Loess-mantled Landscape in Eastern Washington

    Science.gov (United States)

    Walther, S. C.; Roering, J. J.; Almond, P. C.; Hughes, M.

    2005-12-01

    Vegetation varies with climate so it is important to constrain how different vegetation types affect sediment transport. In forested landscapes, tree throw plays a large role in increased sediment transport relative to shrub and grassland. In this study, we quantify soil transport rates in a coniferous forest using hillslope profiles and tephra abundance. The loess-mantled hillslopes of Robinette Mountain in the Blue Mountains, confining the southeastern edge of the Columbia Plateau in southeast Washington State, USA, have been forested since the Holocene transition. Approximately 6800 years ago, the eruption of Mt. Mazama blanketed the region with tephra. Near the crest of hillslopes of different degrees of convexity, we identified and sampled soils for cryptotephra analysis. The depth of the tephra abundance spike is used as a proxy for erosion/exhumation rate since deposition. The slope dependent sediment transport model suggests that the change in elevation with time (or landscape lowering rate) is proportional to the hillslope curvature, with the constant of proportionality referred to as K (m2 yr-1). Therefore, we surveyed slope morphology for comparison with erosion rate at each site. K generally depends on processes such as soil creep, rain splash, variations in soil moisture (wet/dry) and temperature (freeze/thaw), tree throw, and faunal burrowing/biogenic activity. By estimating the value of K we can relate sediment transport to dominant processes in our forested landscape, such as frequency of tree turnover or faunal burrowing, and determine the spatial variability of erosion rates and sediment delivery using topographic hillslope surveys.

  14. Effects of grass contour hedgerow systems on controlling soil erosion in red soil hilly areas, Southeast China

    Institute of Scientific and Technical Information of China (English)

    Ji Fan; Lijiao Yan; Pei Zhang; Ge Zhang

    2015-01-01

    abstract Soil erosion by water is a well-recognized serious environmental problem in the world. While contour hedgerow systems are an effective method for soil water conservation, there are a few studies on its effect in the red soil hilly areas in Southeast China. With a fixed field experiment, we constructed a runoff plot at hilly area in Zhuji County, Zhejiang province, to evaluate the effect of the grass hedgerows in soil water conservation, and to determine the optimized hedgerow patterns. Hemerocallis citrine (HC) and Ophiopogon japonicas (OJ) were selected to build the hedgerows in patterns of one row and two rows. The REE method was used to trace the source of the sediment for a better understanding of the characteristic and mechanism of erosion with hedgerows control. Our results showed that (1) hedgerows reduced erosion and surface runoff by 31.99–67.22% and 15.44–45.11%, respectively; (2) hedgerows delayed the development of rills;(3) hedgerows reduced the soil nutrients loss;(4) hedgerows reshaped the soil physical properties, especially in increasing 4 0.25 mm water-stable aggregates. Taken together, our results suggest that two-row OJ is the optimized contour hedgerow pattern in the experiment condition, and downward sloping land should have the highest priority to take measures for soil water conservation. This research comprehensively studied the effects and mechanism of contour hedgerows in controlling soil and water loss in red soil hilly areas, Southeast China, so that the practice of soil and water conservation can be implemented more effectively in these areas.

  15. Erosion control in orchards and vineyards by a new soil and cover crop management method

    Science.gov (United States)

    Hartl, Wilfried; Guettler, Hans; Auer, Karl; Erhart, Eva

    2016-04-01

    Cover crops are the basis for an erosion-free soil management in orchards and vineyards. The soil cover provided by the foliage and the intensive root formation counteract erosion. Cover crops provide the soil microfauna with fresh organic matter which improves soil structure and porosity. The water demand of cover crops, however, may pose problems for the water supply of the trees and vines in dry seasons. Therefore it is necessary to adjust the growth of the cover crops to the actual water conditions. In years with ample precipitation cover crops may be allowed lush vegetative growth till flowering and formation of seeds. In dry years, the growth of the cover crop must be restricted to stop the competition for water, sometimes even by cutting off the cover crop roots. The course of the weather is incalculable and rainfall may be very variable during the year, so it is sometimes necessary to adust the cover crop management several times a year. A new special equipment, which can perform all the tasks necessary for the flexible cover crop management has been developed together with the agricultural machinery manufacturers Bodenwerkstatt Ertl-Auer GmbH and Güttler GmbH. The GreenManager® device consists of three modules, namely a specific type of cultivator, a harrow and a prismatic roller with seeding equipment, which can be used separately or in combination. The GreenManager® can reduce cover crops by flattening the plants in the whole row middle, by bringing down the cover crops with the harrow, or by horizontally cutting the cover crop roots a few centimetres beneath the soil surface in the central part of the row middle or in the whole row middle. These measures reduce the water competition by cover crops without generating further losses of soil moisture through intensive soil cultivation. At the same time the risk of soil erosion is kept to a minimum, because the soil remains covered by dead plant biomass. In one passage the GreenManager® can direct

  16. RM12-2703 Advanced Rooftop Unit Control Retrofit Kit Field Demonstration: Hawaii and Guam Energy Improvement Technology Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    Doebber, I.; Dean, J.; Dominick, J.; Holland, G.

    2014-03-01

    As part of its overall strategy to meet its energy goals, the Naval Facilities Engineering Command (NAVFAC) partnered with U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) to rapidly demonstrate and deploy cost-effective renewable energy and energy efficiency technologies. This was one of several demonstrations of new and underutilized commercial energy efficiency technologies. The consistent year-round demand for air conditioning and dehumidification in Hawaii provides an advantageous demonstration location for advanced rooftop control (ARC) retrofit kits to packaged rooftop units (RTUs). This report summarizes the field demonstration of ARCs installed on nine RTUs serving a 70,000-ft2 exchange store (large retail) and two RTUs, each serving small office buildings located on Joint Base Pearl Harbor-Hickam (JBPHH).

  17. Storm dissolved organic matter : surface and sub-surface erosion controls its composition

    Science.gov (United States)

    Denis, Marie; Jeanneau, Laurent; Gruau, Gérard; Petitjean, Patrice; Pierson-Wickmann, Anne-Catherine

    2016-04-01

    In headwater catchments, flood events are responsible for exportation of the major part of DOM (dissolved organic matter) during the hydrological year. During these hot moments, the increased flow at the outlet is accompanied with an increase of DOM concentrations, implying the mobilisation of additional DOM sources which could have a different composition than DOM exported during base-flow. Molecular analysis performed on samples coming from the outlet of the Kervidy-Naizin catchment, an agricultural catchment located in France (Critical Zone Observatory AgrHyS) revealed a modification in the distribution of lignin compounds during flood events. This DOM, less biodegraded, could be produced by partition between particulate and dissolved phases when the soil/water ratio is low, that is to say when soil particles are isolated in water. The evolution of DOM composition during storm events has been assumed to reflect a combination of in-stream and in-soil erosion processes. So how soil erosion could be responsible for production of less degraded DOM? And is the composition of soil DOM modified during a storm event? Those questions were investigated during two flood events, by sampling soil solutions with high frequency in riparian soils equipped with zero-tension lysimeters in the Kervidy-Naizin catchment. In the same time stream DOM was sampled at the outlet of the watershed and runoff were investigated. Samples have been filtered at 0.2μm, analysed for DOC and freeze-dried for molecular analysis (thermally assisted hydrolysis methylation - gas chromatography / mass spectrometry). The hydraulic gradient was monitored every 15 minutes using piezometers implemented in the riparian soils and higher up in the toposequence. At the beginning of the events, hydraulic gradient increased rapidly and stayed high during several days. Modification of DOM composition in soil solution were recorded during the hydraulic gradient rise with an increase in the proportion of less

  18. Tectonic erosion, subduction accretion and arc collision as controls on the growth of the continental crust

    Science.gov (United States)

    Clift, P.; Vannucchi, P.; Draut, A.

    2003-04-01

    Subduction plate boundaries, at which tectonic erosion removes material from the overriding plate, account for 57% of the total length of the global subduction system and are favored where convergence rates exceed 7 cm/yr and where the sedimentary cover is less than 1 km. Accretion conversely preferentially occurs in regions of slow convergence (1 km. The slope gradients and taper angle of accretionary plate margins correlates with plate convergence rates, while erosive margin slopes appear to be independent of this. Rates of trench retreat do not appear to correlate with any simple characteristic of the plate interaction, but are largely a function of the history of seamount or ridge collisions. Mass balances of the global subduction system indicate that the entire volume of the continental crust can be recycled through the subduction system every 2.6 Ga. Even in accretionary margins a median of only 32% of the incoming sedimentary mass is accreted over time scales of 10 my or greater, resulting in long-term net loss of continental crust along continental active margins. Average magmatic productivity in the active margins must exceed 75 km3/my if the volume of the continental crust is to reach the slow growth rate indicated by isotopic and continental freeboard arguments. Geological arguments indicate that magmatic accretion rates must be faster in oceanic arcs (87-95 km3/my) and less in the continental arcs (65-83 km3/my). Mass balance arguments in oceanic arcs require that their crustal thicknesses must be Continental growth is principally achieved through the collision of oceanic island arcs to continental margins. Although oceanic arcs are chemically distinct from continental crust, the collision process involves the loss of mafic and ultramafic lower crust and the emplacement of voluminous, high silica, light rare earth element enriched melts, transforming the net composition into something more continental in character.

  19. Escoamento superficial na interação: cobertura vegetal e práticas de controle de erosão Erosion losses from runoff: interaction of soil cover and erosion control practice

    Directory of Open Access Journals (Sweden)

    Marco A. R. de Carvalho

    2012-12-01

    Full Text Available O escoamento da água oriunda das terras agricultadas é o principal fator poluente dos mananciais hídricos nas áreas rurais. Devido a esse fato, faz-se necessário o desenvolvimento e a aplicação de tecnologias que venham a reduzir descargas de resíduos indesejáveis. Nesse sentido, conduziu-se um experimento na área experimental do Departamento de Engenharia Rural - ESALQ/USP, Piracicaba - SP, com o objetivo de avaliar o efeito de diferentes condições de solo, (feijão, gramínea e solo nu e diferentes práticas de controle de erosão (sulco de infiltração, terraço de infiltração e sem práticas de controle de erosão, buscando-se estimar o escoamento superficial. O delineamento estatístico adotado foi o em blocos aleatorizados, em esquema fatorial 3x3, perfazendo 9 tratamentos com 3 repetições. O período de coleta de dados pluviométricos foi de 06 de dezembro de 2007 a 11 de abril de 2008; para isto, utilizou-se de um pluviômetro, com 21,1 cm de diâmetro, instalado na área experimental. Observando-se as perdas de água, em relação às estruturas, tem-se em ordem decrescente de eficiência: Terraço, Sulco e Rampa; e com relação às coberturas, tem-se em ordem decrescente de eficiência: Feijão, Capim e Solo Nu.The flow of sediment from cropped land is the main pollutant of water sources in rural areas. Due to this fact, it is necessary to develop and implement technologies that will reduce water and sediment discharges. Accordingly, an experiment was conducted in the Department of Biosystems Engineering - ESALQ / USP, Piracicaba - SP with the objective to evaluate the effect of different soil cover (bean, grass and bare ground and erosion control practices (wide base terraces and infiltration furrows in slopes (no practices to control erosion while measuring water losses in runoff. The statistical design adopted was randomized blocks in a 3x3 factorial scheme resulting in 9 treatments with 3 replicates (blocks. The

  20. Magnitude of Annual Soil Loss from a Hilly Cultivated Slope in Northern Vietnam and Evaluation of Factors Controlling Water Erosion

    Directory of Open Access Journals (Sweden)

    Kiyoshi Kurosawa

    2009-01-01

    Full Text Available A soil erosion experiment was conducted in northern Vietnam over three rainy seasons to clarify the magnitude of soil loss and factors controlling water erosion. The plot had a low (8% or medium (14.5% slope with land-cover of cassava or morning glory or being bare. Annual soil loss (177 to 2,361 g/m2 was a tolerable level in all low-slope plots but was not in some medium-slope plots. The effects of slope gradient and seasonal rainfall on the mean daily soil loss of the season were confirmed, but the effect of land-cover was not, owing to the small canopy cover ratio or leaf area index during the season. The very high annual soil loss (>2,200 g/m2 observed in the first year of some medium-slope plots was the site-specific effect from initial land preparation. Since the site-specific effect was large, the preparation must be done carefully on the slope.

  1. [Optimization of shelterbelt distribution for the gully erosion control of cultivated slope land in rolling hill black soil region of Northeast China].

    Science.gov (United States)

    Su, Zi-Long; Cui, Ming; Fan, Hao-Ming

    2012-04-01

    Shelterbelt system is one of the main components of cultivated slope land in rolling hill black soil region of Northeast China, which plays an important role in the control of gully erosion. Based on the Quickbird high-resolution remote sensing image and the digital elevation model (DEM), and combining with field survey data, this paper analyzed the effects of shelterbelt system in a small watershed of rolling hill black soil region in Heshan Farm of Heilongjiang Province on the control of gully erosion in the cultivated slope land, and put forward an optimized scheme for gully erosion control based on the features of gully erosion in the cultivated slope land and their relations with the distribution of the shelterbelt system. In the study area, the current distribution of the shelterbelt system promoted the occurrence and development of shallow gully and gully directly and indirectly. The proposed scheme for optimizing the distribution of the present shelterbelts included the adjustment of the direction of the shelterbelt perpendicular to the aspect of slope, the enhancement of the maintenance and regeneration of the shelterbelts to reduce the gaps of the shelterbelts, the increase of the shelterbelt number, and the decrease of the distances between shelterbelts. A method for calculating the shelterbelt number and the distances between the shelterbelts was also given. This study could provide scientific basis for the gully erosion control and the shelterbelts programming in the cultivated slope land of rolling hill black soil region.

  2. Effectiveness of hydrological forest restoration projects on soil erosion control in Mediterranean catchment; Efectividad de los proyectos de restauracion hidrologico forestal para el control de la erosion en cuencas mediterraneas

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, V. M.; Boix Fayos, C.; Vente, J. de; Martinez-Mena, M.; Barbera, G. G.

    2009-07-01

    Extensive land use changes have occurred in many Mediterranean catchments as a result of reforestation and the abandonment of agricultural activities. Besides this, the establishment of check-dams has been promoted to reduce soil erosion and sediment transport. In this study a combination of field work, mapping and modelling was used to test influence of land use scenarios with and without sediment control structures on sediment yield at catchment scale. Model simulation shows that in a scenario without check-dams, the land used changes between 1956 and 1997 caused a progressive decrease in sediment yield of 54%. In a scenario without land use changes but with check-dams, about 77% of the sediment yield was retained behind the dams. Both land use changes and check-dams are effective measures decreasing sediment yield in catchment, however they act at very different temporal scales. (Author) 5 refs.

  3. Latitudinal Controls on Topography: The Role of Precipitation and Fluvial Erosion

    Science.gov (United States)

    Sorensen, C.; Yanites, B.

    2014-12-01

    Observations from the North and South American Cordillera show that mean and maximum elevations decrease with increasing latitude. The trend in elevation follows the latitudinal dependence of snowline altitudes. This correlation between elevation and snowline altitude has been the impetus behind the glacial 'buzzsaw' hypothesis, which states that glaciers limit the elevation of mountain peaks. Underlying this hypothesis is an assumption that elevations prior to glaciation were either uniform, randomly distributed, or followed a pattern that is no longer present. However, there may be other factors that are responsible for these patterns, such as latitudinal trends in precipitation. Here, we address this assumption and the necessity of glacial erosion in explaining the latitudinal trend in elevation. We use the CHILD landscape evolution model parameterized by modern precipitation data along a latitudinal gradient in the Andes to predict the topography in the absence of glaciation. Using NCEP/NCAR Reanalysis precipitation data from 1981-2010, we derive storm duration, intensity, and frequency statistics for a series of locations along the Andean orogen. For each location, we run a model using a sequence of storms generated from these statistics. Erodibility and rock-uplift are held constant between the different locations and the models are run until topographic steady-state is achieved. We also present runs exploring the role of a threshold for bedrock detachment in the modeled results. For each run, we track the maximum and mean elevation as well as the time to steady-state. Preliminary results for all cases show that fluvial processes alone are sufficient to account for the latitudinal dependence of topography. For example, landscapes produced with precipitation statistics similar to the dry central Andes are more than an order of magnitude higher than landscapes from the southern, wetter, part of the orogen. Future analysis will use precipitation data from

  4. Modeling of state of vegetation and soil erosion over large areas

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A vegetation-erosion model was developed to assess the extent of soil erosion and development trend of vegetation in the context of existing and contemplated vegetation-based soil erosion controls under different climatic, topographical and soil conditions. The model recognizes four vegetation-mediated soil erosion states: (i) an expanding vegetation coverage coupled with reduced erosion (C), (ii) a deteriorating vegetation coverage coupled with increased erosion (A), (iii) two transitional states between A and C, one with increasing erosion and vegetation coverage (B) and the other with decreasing erosion and vegetation coverage (D). With the model, the vegetation-erosion state of any particular area can be quantitatively described, by way of a vegetation-erosion chart, for varying climate, soil and topographic conditions, as demonstrated for the Xishan region, the East River basin, the Wangjiagou and Anjiagou watersheds (Loess Plateau), and the Xiaojiang watersheds (hot and dry valleys in the upper Yangtze River basin) in China. This paper presents the principles and results of area-specific investigations that track the fractions of the areas covered by vegetation and experiencing soil erosion (with soil loss determined in t/km2yr). This is done within the context of local soil erosion control initiatives via re-vegetation efforts, or the lack thereof, over the course of 30 years. The effectiveness of reforestation and erosion-control measures vary under different climatic, topographical and soil conditions. The vegetation may be quickly restored in the hot and wet East River basin but is very difficult on the dry and cold Loess Plateau. In the hot and dry valleys the vegetation can be restored if erosion is controlled and intensive reforestations for small watersheds are performed.

  5. Measurement of the fluorescence of crop residues: A tool for controlling soil erosion

    Science.gov (United States)

    Daughtry, C. S. T.; Mcmurtrey, J. E., III; Chappelle, E. W.; Hunter, W. J.

    1994-01-01

    Management of crop residues, the portion of a crop left in the field after harvest, is an important conservation practice for minimizing soil erosion and for improving water quality. Quantification of crop residue cover is required to evaluate the effectiveness of conservation tillage practices. Methods are needed to quantify residue cover that are rapid, accurate, and objective. The fluorescence of crop residue was found to be a broadband phenomenon with emission maxima at 420 to 495 nm for excitations of 350 to 420 nm. Soils had low intensity broadband emissions over the 400 to 690 nm region for excitations of 300 to 600 nm. The range of relative fluorescence intensities for the crop residues was much greater than the fluorescence observed of the soils. As the crop residues decompose their blue fluorescence values approach the fluorescence of the soil. Fluorescence techniques are concluded to be less ambiguous and better suited for discriminating crop residues and soils than reflectance methods. If properly implemented, fluorescence techniques can be used to quantify, not only crop residue cover, but also photosynthetic efficiency in the field.

  6. Soil erosion control, plant diversity, and arthropod communities under heterogeneous cover crops in an olive orchard.

    Science.gov (United States)

    Gómez, José Alfonso; Campos, Mercedes; Guzmán, Gema; Castillo-Llanque, Franco; Vanwalleghem, Tom; Lora, Ángel; Giráldez, Juan V

    2017-01-30

    A 3-year experiment compared in an olive orchard the effect of different cover crops' composition on runoff, water erosion, diversity of annual plants, and arthropod communities which could provide an alternative to conventional management based on tillage (CT). The cover crops evaluated were a seeded homogeneous grass (GC), a seeded mix of ten different species (MCseeded), and a non-seeded cover by vegetation naturally present at the farm after 20 years of mowing (MCnatural). The results suggest that heterogeneous cover crops can provide a viable alternative to homogeneous ones in olives, providing similar benefits in reducing runoff and soil losses compared to management based on bare soil. The reduction in soil loss was particularly large: 46.7 in CT to 6.5 and 7.9 t ha(-1) year(-1) in GC and MCseeded, respectively. The heterogeneous cover crops resulted in greater diversity of plant species and a modification of the arthropod communities with an increased number of predators for pests. The reduction of the cost of implanting heterogeneous cover crops, improvement of the seeding techniques, and selection of species included in the mixes require additional research to promote the use of this practice which can deliver enhanced environmental benefits.

  7. Lincoln Park shoreline erosion control project: Monitoring for surface substrate, infaunal bivalves and eelgrass, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Antrim, L.D.; Thom, R.M.; Gardiner, W.W. [Battelle/Marine Sciences Lab., Sequim, WA (United States)

    1993-09-01

    In 1988, the US Army Corps of Engineers and the City of Seattle placed material on the upper beach at Lincoln Park, in West Seattle, Washington. The fill served to mitigate shoreline erosion that had caused undercutting and collapse of the seawall in several places. A series of pre- and post-construction studies have been conducted to assess the impacts to marine biota of fill placement and movement of surface substrate. This study was designed to monitor infaunal bivalves and eelgrass from intertidal areas in and adjacent to the area of original fill placement. Findings from this survey were compared to previous survey results to determine (1) if recruitment of infaunal bivalves to the fill area has occurred, (2) if infaunal bivalve densities outside the fill area are stable, and (3) if eelgrass distribution and abundance have remained stable along the adjacent shoreline. To maximize comparability of findings from this survey with previous studies, sampling techniques, transects, and tidal elevations were consistent with previous studies at this site.

  8. 中国主要水蚀区土壤侵蚀过程与调控研究%Research into Soil Erosion Processes and Control in Major Water Erosion Regions of China

    Institute of Scientific and Technical Information of China (English)

    李锐

    2011-01-01

    The project,"Research into soil erosion processes and control in the major water erosion regions of China",aims to address the urgent needs of China′s national strategy and scientific developments of soil and water conservation.Taking the 4 water erosion regions of northeast black soil,northwest loess,South China red soil and southwest purple soil as the main study areas,the research has concentrated on soil erosion process,modeling and control mechanisms.After more than 4 years research,the following have been achieved: revealing soil erosion development processes and spatial patterns,factors and mechanisms of different types at different scales;developing a Chinese multi-scale soil erosion prediction modeling system;developing methods of evaluation for impacts of soil erosion/conservation on environment,and integrating soil erosion control models to fit into the natural ecology and social economy in different regions.All of these achievements have enriched and developed soil and water conservation science,and provide a theoretical basis for the national soil and water conservation strategy and planning in China.%国家重点基础研究发展计划(973)项目"中国主要水蚀区土壤侵蚀过程与调控研究"针对国家对土壤侵蚀防治对策基础理论的迫切需求和国际学科前沿重大问题,选择东北黑土漫岗丘陵区、西北黄土高原区、南方红壤丘陵区和西南紫色土山丘区等4个主要水力侵蚀区,从侵蚀过程、侵蚀模型和侵蚀调控3个层面进行了系统研究。揭示了不同方式和不同尺度下土壤侵蚀发生发展的过程及其空间格局、影响因子和作用机制;构建了中国多尺度水蚀预报模型;提出了水土流失与水土保持的环境效应评价指标体系与方法;综合集成了适应自然生态过程和人类活动的水土流失调控范式。该项研究成果丰富和发展了具有中国特色的水土保持科学,为国家制定水土保持

  9. The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Main Report.

    Science.gov (United States)

    1981-12-01

    of long-term. comprehensive studies ins ols ing channel alignment, bank stabilization, or navigation channeli/ation. (U. S. ArmN Engineer Civil Works...Program of the Civil Works Investigation Study on Materials U.S. Army Engineer Waterways Experiment Station, Vicksburg, Mississippi Technical Report...Pearl River Basin Development District, Mississippi; (64) La Asociacion De Santa Rosa De Lima De Abiquiu. Inc., New Mexico; (65) Pittsylvania Soil and

  10. Land degradation and erosion control within the Moldavian Plateau of eastern Romania: a case study from Racova catchment

    Science.gov (United States)

    Niacsu, Lilian; Ionita, Ion; Samoila, Claudia; Grigoraş, Georgel

    2017-04-01

    Land degradation has been recognized as the major environmental threat in the Moldavian Plateau of eastern Romania. The Racova catchment, located in the central part of this area and extending on 32,908 ha, is significantly subjected to moderate-high rates of soil erosion, gullying, landslides and reservoir siltation. Several methods have been used to estimate land degradation indicators, such as classical research methods (field surveys and mapping, mathematical-statistical processing), present-day methods based on the GIS software, the Cs-137 technique etc. For example, the landslide inventory resulted from data collected during field surveys, interpretation of the 2005 and 2009 aerial orthophotos, exploiting very-high resolution digital elevation model (DEM) based on the topographical plans at 1:5,000 scale, and the visual analysis of products obtained from 2012 LiDAR DEM (slope map and shaded relief images). The results obtained showed that landslides, in any shape or age, are the most typical degradation processes in the Racova catchment, particularly extending on steep slopes representing north or west looking cuesta fronts, usually. At present, they cover half of the study area and most are inactive. The gullied systems amounting 4% of the catchment area consist of both types of gullies, discontinuous and continuous along valley-bottoms, respectively. In addition, the major role of gully erosion in triggering landslides and high reservoir siltation rate has been considered. Extensive conservation practices have been deployed over the 70's and 80's, namely: contour farming on arable land (under strip-cropping, buffer strip-cropping and bench terraces), reforestation over 2,000 ha (especially with black-locust on the active landslides), check dams to control gully erosion etc. Since 1990, two land reforms have been implemented (the Act No. 18/1991 and the Act No.1/2000) and their impact was very marked on soil conservation and crop yields. The major effect of

  11. Modeling erosion and sediment control practices in RUSLE 2.0: A management approach for natural gas well sites in Denton County, TX, USA

    Science.gov (United States)

    Sediment yields from natural gas well sites can be substantial and warrant consideration of appropriate erosion and sediment control Best Management Practices(BMPs). Version 2 of the Revised Universal Soil Loss Equation (RUSLE 2.0) was used to predict sediment yields and evaluate the efficiency of ...

  12. The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Appendix E. Missouri River Demonstration Projects. Volume 1.

    Science.gov (United States)

    1981-12-01

    Peachleaf Willow Salix amygdaloides -. Cottonwood Populus deltoides Russian Olive Elaeagnus angustifolia Buffaloberry Shepherdia argentea In addition, 8,000... Elaeagnus angustifolia Buffaloberry Shepherdia argentea Red-Osier Dogwood Cornus stolonifera Golden Willow Salix alba vitelina Hackberry Celtis

  13. The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Appendix D. Ohio River Demonstration Projects.

    Science.gov (United States)

    1981-12-01

    SERICCA 20 MOUNDSVILLE, W. VA. PHALARIS ARUNOINACEA REED CANARY GRASS 2 IT 01AGROSTIS AL&A "to TOP 5S T LOTUS CORNICULATUS ISIROSFOOT TRFIL 10 OHIO... CORNICULATUS BIROSFOOT TREFOIL to F ,*21 LAETPESTUCA ARUNOHNAC A TALL fESCUE 0S I TE LOTUS CORNICULATUS SIROSFOOT TREFOIL .00H1 RIVE PLATE 19 D-2-37...AGROS-ris .4LBA KED 7TOP s LorLJS CORNICULATUS AJ*DSFooT rXEF’OL 10 C FKSruc9 fiRuNDINACER, TALL FffSC IAf CPCV.31,VLTA) 30 CORrD/VILq4 Vh9#9PffYC.is

  14. The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Appendix G. Demonstration Projects on Other Streams, Nationwide. Volume 2.

    Science.gov (United States)

    1981-12-01

    Clermont County residents in the labor market are employed in Hamilton County. The employment structure of Clermont County in 1970 consisted of a high...percent of manufacturing (42 percent), wholesale and retail (17 percent), and 11 percent in services. The remaining market consists of a relatively...listed by either the state or the U.S. Department of Interior, but which is capable of generating special enthusiasm and concern among birdwatchers , are

  15. Erosion sculptures

    Science.gov (United States)

    Ristroph, Leif; Moore, M. N. J.; Childress, Stephen; Shelley, Michael; Zhang, Jun

    2012-11-01

    Erosion by flowing fluids carves the striking landscapes imprinted on the Earth and on the surfaces of our neighboring worlds. In these processes, solid boundaries both influence and are shaped by the surrounding fluid, but the emergence of morphology as a result of this interaction is not well understood. We study the coevolution of shape and flow in the context of clay bodies immersed in fast flowing water. Although commonly viewed as a smoothing process, we discover that erosion sculpts surprisingly sharp points and corners that persist as the body shrinks. These features result from a natural tendency to form surfaces that erode uniformly, and we argue that this principle may also apply to the more complex scenarios that occur in nature.

  16. Assessment of effectiveness of different dosage regimens of pantoprazole in controlling symptoms and healing esophageal lesions of patients with mild erosive esophagitis

    Directory of Open Access Journals (Sweden)

    MORETZSOHN Luciana Dias

    2002-01-01

    Full Text Available Background - Gastroesophageal reflux disease is a very common affection, and esophageal involvement is particularly frequent. The means to effectively control symptoms and improve esophageal inflammation in these patients is to reduce esophageal acid exposure. For this purpose, we use gastric proton pump inhibitor, that can suppress gastric acid secretion. Aim - To compare the effectiveness of two different pantoprazole dosage regimens (20 and 40 mg/day, in controlling symptoms and healing esophageal lesions of patients with mild erosive esophagitis. Material and Methods - Fifty-seven patients with endoscopically confirmed mild erosive esophagitis characterized as non-confluent erosions in the distal esophagus, were randomly to be treated either with pantoprazole 20 mg/day (group I, 28 patients or 40 mg/day (group II, 29 patients over a period of 4 weeks. After treatment completion, the patients were assessed for clinical and endoscopic outcome, i.e., absence of erosions in distal esophagus and improvement of gastroesophageal reflux symptoms. Results - At the end of the treatment, 73.1% of the patients in group I and 85.7% of the patients in group II had endoscopic improvement. We also observed, that 88.5% of the patients in group I and 92.9% of the patients in group II had complete elimination of heartburn and regurgitation. Conclusion - Pantoprazole dosage regimens of 20 mg/day and 40 mg/day provide equivalent effectiveness in controlling symptoms and healing esophageal lesions of mild esophagitis.

  17. Soil Erosion and Nutrient Losses control by Plant Covers: Environmental Implications for a Subtropical Agroecosystem (SE Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Pleguezuelo, C. R.; Duran-Zuazo, V. H.; Martin-Peinado, F. J.; Franco-Tarifa, D.; Martinez-Raya, A.; Francia-Martinez, J. R.; Carceles-Rodriguez, B.; Arroyo-Panadero, L.; Casado, J. P.

    2009-07-01

    Soil erosion, in addition to causing on-site loss of topsoil and reducing the productivity of the land, brings about major off-site environmental effects such as water body pollution and eutrophication. In the Mediterranean area, this fact is especially relevant where precipitation is characterized by scarcity, torrent storms and extreme variability in space and time. To study the effects of soil erosion runoff potential pollution we installed six erosion plots on the taluses of orchard terraces where an intensive irrigated agriculture based on subtropical crops has been established. (Author)

  18. Chapter 6: Tree-compatible ground covers for reforestation and erosion control

    Science.gov (United States)

    J. Burger; V. Davis; C. Zipper; J. Skousen; C. Barton; P. Angel

    2017-01-01

    Productive native forests create economic value for landowners, produce raw materials for wood-based products, and provide benefits such as watershed control, water quality protection, carbon storage, wildlife habitat, and native plant diversity. Owners of lands mined for coal in the Appalachian region are increasingly interested in assuring that productive forests are...

  19. Maintenance and Control of Erosion and Sediment Along Secondary Roads and Tertiary Trails.

    Science.gov (United States)

    1997-07-01

    wildflowers , or even grain crops to increase the roughness coefficient of the channel. Sediment control measures are based on intercep- tion and detention...fallowed seedbeds is effective. In California grasslands, light disking * Under wet conditions, rolling can be very after the first fall rains, followed by

  20. Characterization and Erosion Modeling of a Nozzle-Based Inflow-Control Device

    DEFF Research Database (Denmark)

    Olsen, Jógvan Juul; Hemmingsen, Casper Schytte; Bergmann, Line

    2017-01-01

    In the petroleum industry, water-and-gas breakthrough in hydrocarbon reservoirs is a common issue that eventually leads to uneconomic production. To extend the economic production lifetime, inflow-control devices (ICDs) are designed to delay the water-and-gas breakthrough. Because the lifetime of...

  1. Interim Field Evaluation of Windrow Revetment. Missouri River, Section 32, Streambank Erosion Control.

    Science.gov (United States)

    1980-03-01

    CLY’,ON ’v AT v 9 eo - 0 C-.~ .. 0. 00. ( i 0O 0 CEA CONY 0 0 0 .. 0 0r 1 ~ . L0ON~~ DEMONSTRATION SIT ::X___ __ 0 0 CEA CONT DIO CUT LEGEN ZLITCN TETIR...RIE loo 3lIRVE 00 RANGE *6 AVG. VEL. FOR CHANNEL = 3.90 FPS 10 NOV. 1976 RAN %Q’:=S%-SEE NOTE I QGP = 35.000 CFS SEE Qvs = 3S,00CFS rNOTE 4 QLrv

  2. 狗牙根和牛鞭草的消浪减蚀作用%Role of Cynodon dactylon L.and Hemarthria altissimain wave attenuation and erosion control

    Institute of Scientific and Technical Information of China (English)

    钟荣华; 贺秀斌; 鲍玉海; 杨克君; 高进长; 吕发友

    2015-01-01

    Soil erosion and bank degradation is a major post-dam concern regarding the riparian zone of Three Gorges Reservoir (TGR). The development and succession of vegetation are the main countermeasures, especially to enhance bank stability and mitigate soil erosion. Thus, the role of forCynodon dactylon(L.) Pers.andHemarthria altissima(Poir.) Stapf et C. E. Hubb. inwave attenuation and erosion control was measured via the flume experiments. The results showed that the two grass species play an important role in wave attenuation and erosion control. The effects of wave attenuation and erosion control capabilities for the two species were different. The mean wave dissipation coefficient (MWDC) for Cynodon dactylon(L.) Pers. andHemarthria altissima (Poir.) Stapf et C. E. Hubb. were 0.37 and 0.30, respectively, with the wave period of 1.2 s to 1.5 s. Nevertheless, the values of MWDCfor Hemarthria altissima(Poir.) Stapf et C. E. Hubb.was similar toCynodon dactylon(L.) Pers.(ranged from 0.15 to 0.30) when the wave period was between 0.8 s to 1.2 s. The MWDCvalues of 0.43 and 0.30 were responded forCynodon dactylon(L.) Pers. under 80% and 40% area coverage, respectively. In contrast, the MWDCvalues forHemarthria altissima (Poir.) Stapf et C. E. Hubb. were 0.35 and 0.24, respectively, under two different coverage. The MWDCvalues forCynodon dactylon(L.) Pers. with a wave height of 8 and 4 cm were 0.34 and 0.39, respectively; whilst, the ones forHemarthria altissima (Poir.) Stapf et C. E. Hubb. were 0.15 and 0.32, respectively. The MWDCvalues showed generally increasing trend with increasing wave period. Species studied also significantly reduced wave induced soil erosion. The results of washout tests indicated the soil erosion modulus decreased with increasing eroded time. The largest erosion modulus was measured for bare land (799.40 g/(m2·min)), followed byHemarthria altissima(Poir.) Stapf et C. E. Hubb. (57.28 g/(m2·min)),Cynodon dactylon(L.) Pers.(17.63 g/(m2·min)). When

  3. A PERMEABLE ACTIVE AMENDMENT CONCRETE (PAAC) FOR CONTAMINANT REMEDIATION AND EROSION CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    Knox, A.; Paller, M.; Dixon, K.

    2012-06-29

    The final project report for SEED SERDP ER - 2134 describes the development of permeable active amendment concrete (PAAC), which was evaluated through four tasks: 1) development of PAAC; 2) assessment of PAAC for contaminant removal; 3) evaluation of promising PAAC formulations for potential environmental impacts; and 4) assessment of the hydraulic, physical, and structural properties of PAAC. Conventional permeable concrete (often referred to as pervious concrete) is concrete with high porosity as a result of an extensive and interconnected void content. It is made from carefully controlled amounts of water and cementitious materials used to create a paste that forms a coating around aggregate particles. The mixture has a substantial void content (e.g., 15% - 25%) that results in a highly permeable structure that drains quickly. In PAAC, the aggregate material is partly replaced by chemically-active amendments that precipitate or adsorb contaminants in water that flows through the concrete interstices. PAAC combines the relatively high structural strength, ample void space, and water permeability of pervious concrete with the contaminant sequestration ability of chemically-active amendments to produce a new material with superior durability and ability to control contaminant mobility. The high surface area provided by the concrete interstices in PAAC provides significant opportunity for contaminants to react with the amendments incorporated into the concrete matrix. PAAC has the potential to immobilize a large variety of organic and inorganic contaminants by incorporating different active sequestering agents including phosphate materials (rock phosphate), organoclays, zeolite, and lime individually or in combinations.

  4. [Spreading experience of demonstration plots and strengthening control of parasitic diseases].

    Science.gov (United States)

    Yu, Wang

    2011-10-01

    This paper summarizes the achievements and experiences of demonstration plots carrying out comprehensive control measures of parasite diseases in China, and elaborates the hard task of the control of parasitic diseases as one of main public health problems. The article also elaborates the significance of spreading the experiences of demonstration plots carrying out comprehensive control measures of parasite diseases for improving the health of people and promoting the construction of new countryside.

  5. Demonstration of EDFA Cognitive Gain Control via GMPLS for Mixed Modulation Formats in Heterogeneous Optical Networks

    DEFF Research Database (Denmark)

    Oliveira, Juliano R.; Caballero Jambrina, Antonio; Magalhães, Eduardo

    2013-01-01

    We demonstrate cognitive gain control for EDFA operation in real-time GMPLS controlled heterogeneous optical testbed with 10G/100G/200G/400G lightpaths. Cognitive control maintains the network BER below FEC-limit for up to 6 dB of induced attenuation penalty....

  6. Optimal control of tip-tilt modes on-sky adaptive optics demonstration

    NARCIS (Netherlands)

    Doelman, N.J.; Fraanje, P.R.; Breeje, R. den

    2011-01-01

    An H2-optimal control approach for Adaptive Optics has been validated in an on-sky experiment on a solar telescope. A substantial performance improvement over the integrator control approach is demonstrated for control of the tip-tilt modes. The experimental results correspond reasonably well with

  7. SOIL EROSION PROCESS RESEARCH AND ITS POTENTIAL IMPACT ON EROSION PREDICTION MODEL DEVELOPMENT

    Institute of Scientific and Technical Information of China (English)

    Chi-hua HUANG; Fenli ZHENG

    2005-01-01

    This paper highlights past efforts in developing erosion process concepts that lead to the development of the current process-based erosion prediction model, i.e., WEPP. Recent progress includes the development of a multiple-box system that can simulate hillslope hydrologic conditions. Laboratory procedures enable the quantification of near-surface hydrologic effects, i.e.,artesian seepage vs. drainage, on the soil erosion process and sediment regime, flow hydraulics, and sediment transport and deposition processes. These recent findings improve soil erosion science and provide new erosion control strategies that may have additional environmental benefits relative to the traditional erosion control practices. The paper also discusses the potential impacts of the erosion process on erosion model development and future research directions of soil erosion process research and model development.

  8. Influence of inhomogeneous static magnetic field-exposure on patients with erosive gastritis: a randomized, self- and placebo-controlled, double-blind, single centre, pilot study.

    Science.gov (United States)

    Juhász, Márk; Nagy, Viktor L; Székely, Hajnal; Kocsis, Dorottya; Tulassay, Zsolt; László, János F

    2014-09-06

    This pilot study was devoted to the effect of static magnetic field (SMF)-exposure on erosive gastritis. The randomized, self- and placebo-controlled, double-blind, pilot study included 16 patients of the 2nd Department of Internal Medicine, Semmelweis University diagnosed with erosive gastritis. The instrumental analysis followed a qualitative (pre-intervention) assessment of the symptoms by the patient: lower heartburn (in the ventricle), upper heartburn (in the oesophagus), epigastric pain, regurgitation, bloating and dry cough. Medical diagnosis included a double-line upper panendoscopy followed by 30 min local inhomogeneous SMF-exposure intervention at the lower sternal region over the stomach with peak-to-peak magnetic induction of 3 mT and 30 mT m(-1) gradient at the target site. A qualitative (post-intervention) assessment of the same symptoms closed the examination. Sham- or SMF-exposure was used in a double-blind manner. The authors succeeded in justifying the clinically and statistically significant beneficial effect of the SMF- over sham-exposure on the symptoms of erosive gastritis, the average effect of inhibition was 56% by p = 0.001, n = 42 + 96. This pilot study was aimed to encourage gastroenterologists to test local, inhomogeneous SMF-exposure on erosive gastritis patients, so this intervention may become an evidence-based alternative or complementary method in the clinical use especially in cases when conventional therapy options are contraindicated. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  9. Fallout radionuclide-based techniques for assessing the impact of soil conservation measures on erosion control and soil quality: an overview of the main lessons learnt under an FAO/IAEA Coordinated Research Project.

    Science.gov (United States)

    Dercon, G; Mabit, L; Hancock, G; Nguyen, M L; Dornhofer, P; Bacchi, O O S; Benmansour, M; Bernard, C; Froehlich, W; Golosov, V N; Haciyakupoglu, S; Hai, P S; Klik, A; Li, Y; Lobb, D A; Onda, Y; Popa, N; Rafiq, M; Ritchie, J C; Schuller, P; Shakhashiro, A; Wallbrink, P; Walling, D E; Zapata, F; Zhang, X

    2012-05-01

    This paper summarizes key findings and identifies the main lessons learnt from a 5-year (2002-2008) coordinated research project (CRP) on "Assessing the effectiveness of soil conservation measures for sustainable watershed management and crop production using fallout radionuclides" (D1.50.08), organized and funded by the International Atomic Energy Agency through the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. The project brought together nineteen participants, from Australia, Austria, Brazil, Canada, Chile, China, Japan, Morocco, Pakistan, Poland, Romania, Russian Federation, Turkey, United Kingdom, United States of America and Vietnam, involved in the use of nuclear techniques and, more particularly, fallout radionuclides (FRN) to assess the relative impacts of different soil conservation measures on soil erosion and land productivity. The overall objective of the CRP was to develop improved land use and management strategies for sustainable watershed management through effective soil erosion control practices, by the use of ¹³⁷Cs (half-life of 30.2 years), ²¹⁰Pb(ex) (half-life of 22.3 years) and ⁷Be (half-life of 53.4 days) for measuring soil erosion over several spatial and temporal scales. The environmental conditions under which the different research teams applied the tools based on the use of fallout radionuclides varied considerably--a variety of climates, soils, topographies and land uses. Nevertheless, the achievements of the CRP, as reflected in this overview paper, demonstrate that fallout radionuclide-based techniques are powerful tools to assess soil erosion/deposition at several spatial and temporal scales in a wide range of environments, and offer potential to monitor soil quality. The success of the CRP has stimulated an interest in many IAEA Member States in the use of these methodologies to identify factors and practices that can enhance sustainable agriculture and minimize land degradation.

  10. Application of video-cameras for quality control and sampling optimisation of hydrological and erosion measurements in a catchment

    Science.gov (United States)

    Lora-Millán, Julio S.; Taguas, Encarnacion V.; Gomez, Jose A.; Perez, Rafael

    2014-05-01

    Long term soil erosion studies imply substantial efforts, particularly when there is the need to maintain continuous measurements. There are high costs associated to maintenance of field equipment keeping and quality control of data collection. Energy supply and/or electronic failures, vandalism and burglary are common causes of gaps in datasets, reducing their reach in many cases. In this work, a system of three video-cameras, a recorder and a transmission modem (3G technology) has been set up in a gauging station where rainfall, runoff flow and sediment concentration are monitored. The gauging station is located in the outlet of an olive orchard catchment of 6.4 ha. Rainfall is measured with one automatic raingauge that records intensity at one minute intervals. The discharge is measured by a flume of critical flow depth, where the water is recorded by an ultrasonic sensor. When the water level rises to a predetermined level, the automatic sampler turns on and fills a bottle at different intervals according to a program depending on the antecedent precipitation. A data logger controls the instruments' functions and records the data. The purpose of the video-camera system is to improve the quality of the dataset by i) the visual analysis of the measurement conditions of flow into the flume; ii) the optimisation of the sampling programs. The cameras are positioned to record the flow at the approximation and the gorge of the flume. In order to contrast the values of ultrasonic sensor, there is a third camera recording the flow level close to a measure tape. This system is activated when the ultrasonic sensor detects a height threshold, equivalent to an electric intensity level. Thus, only when there is enough flow, video-cameras record the event. This simplifies post-processing and reduces the cost of download of recordings. The preliminary contrast analysis will be presented as well as the main improvements in the sample program.

  11. Analysis and control of erosion by solid particles in the elements of the flow system of steam turbines; Analisis y control de erosion por particulas solidas en los elementos del sistema de flujo de turbinas de vapor

    Energy Technology Data Exchange (ETDEWEB)

    Mazur Czerwiec, Zdzislaw; Campos Amezcua, Alfonso; Campos Amezcua, Rafael [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2010-07-01

    The analysis of erosion by solid particles is presented of different elements of the flow channel of the steam turbines that operate in Mexico: nozzles, stop valves, blade bosses, labyrinth seals and rotor disc; using tools of of Computational Fluid Dynamics (CFD). In these main elements of turbines a strong problem of erosion was registered that threatens the reliable operation of the turbines, its availability and its optimal yield. With base on the results of the numerical analyses, the design modifications of the different elements were developed from the flow channel of the steam turbines, in order to reduce the erosion and thus diminishing the energy losses and increasing the steam turbine efficiency. This work presents the main benefits that the Thermoelectric Power Plants obtain with the reduction of the erosion by solid particles that affect the critical components of steam turbines: extension of the period between maintenance, replacement of components, reduction of operation and maintenance costs of the turbines, and extension of the useful life of the main components. [Spanish] Se presenta el analisis de erosion por particulas solidas de diferentes elementos del canal de flujo de las turbinas de vapor que operan en Mexico: toberas, valvula de paro, tetones de los alabes, sellos de laberinto y disco del rotor; utilizando herramientas de Dinamica de Fluidos Computacional (DFC). En estos elementos principales de turbinas se registro un fuerte problema de erosion que amenaza la operacion confiable de las turbinas, su disponibilidad y su rendimiento optimo. Con base en los resultados de los analisis numericos, se desarrollaron las modificaciones de diseno de los diferentes elementos del canal de flujo de las turbinas de vapor, con el proposito de reducir la erosion y asi, disminuir las perdidas de energia e incrementar el rendimiento de las turbinas de vapor. Este trabajo presenta los principales beneficios que obtienen las Centrales Termoelectricas con la

  12. Demonstration of Optically Controlled re-Routing in a Photonic Crystal Three-Port Switch

    DEFF Research Database (Denmark)

    Combrié, S.; Heuck, Mikkel; Xavier, S.

    2012-01-01

    We present an experimental demonstration of optically controlled re-routing of a signal in a photonic crystal cavity-waveguide structure with 3 ports. This represents a key functionality of integrated all-optical signal processing circuits....

  13. Relations between rainfall–runoff-induced erosion and aeolian deposition at archaeological sites in a semi-arid dam-controlled river corridor

    Science.gov (United States)

    Collins, Brian; Bedford, David; Corbett, Skye; Fairley, Helen; Cronkite-Ratcliff, Collin

    2016-01-01

    Process dynamics in fluvial-based dryland environments are highly complex with fluvial, aeolian, and alluvial processes all contributing to landscape change. When anthropogenic activities such as dam-building affect fluvial processes, the complexity in local response can be further increased by flood- and sediment-limiting flows. Understanding these complexities is key to predicting landscape behavior in drylands and has important scientific and management implications, including for studies related to paleoclimatology, landscape ecology evolution, and archaeological site context and preservation. Here we use multi-temporal LiDAR surveys, local weather data, and geomorphological observations to identify trends in site change throughout the 446-km-long semi-arid Colorado River corridor in Grand Canyon, Arizona, USA, where archaeological site degradation related to the effects of upstream dam operation is a concern. Using several site case studies, we show the range of landscape responses that might be expected from concomitant occurrence of dam-controlled fluvial sand bar deposition, aeolian sand transport, and rainfall-induced erosion. Empirical rainfall-erosion threshold analyses coupled with a numerical rainfall–runoff–soil erosion model indicate that infiltration-excess overland flow and gullying govern large-scale (centimeter- to decimeter-scale) landscape changes, but that aeolian deposition can in some cases mitigate gully erosion. Whereas threshold analyses identify the normalized rainfall intensity (defined as the ratio of rainfall intensity to hydraulic conductivity) as the primary factor governing hydrologic-driven erosion, assessment of false positives and false negatives in the dataset highlight topographic slope as the next most important parameter governing site response. Analysis of 4+ years of high resolution (four-minute) weather data and 75+ years of low resolution (daily) climate records indicates that dryland erosion is dependent on short

  14. The effect of single-application fluoride treatment on simulated gastric erosion and erosion-abrasion of enamel in vitro.

    Science.gov (United States)

    Austin, Rupert S; Stenhagen, Kjersti Refsholt; Hove, Lene Hystad; Tveit, Anne Bjørg; Moazzez, Rebecca V; Bartlett, David W

    2014-01-01

    To compare single-application fluoride formulations on enamel erosion and erosion-abrasion in vitro. Enamel specimens were pretreated with either sodium, tin, titanium, or sodium/calcium fluoride and subjected to either an erosion model or an erosion-abrasion model, after which optical profilometry was used to measure enamel step height loss. For erosion, the titanium fluoride (P .05). For erosion-abrasion, the titanium fluoride increased enamel loss in comparison to control (P fluoride has differing effects on enamel loss from erosion and erosion-abrasion models.

  15. Soil erosion dynamics response to landscape pattern.

    Science.gov (United States)

    Ouyang, Wei; Skidmore, Andrew K; Hao, Fanghua; Wang, Tiejun

    2010-02-15

    Simulating soil erosion variation with a temporal land use database reveals long-term fluctuations in landscape patterns, as well as priority needs for soil erosion conservation. The application of a multi-year land use database in support of a Soil Water Assessment Tool (SWAT) led to an accurate assessment, from 1977 to 2006, of erosion in the upper watershed of the Yellow River. At same time, the impacts of land use and landscape service features on soil erosion load were assessed. A series of supervised land use classifications of Landsat images characterized variations in land use and landscape patterns over three decades. The SWAT database was constructed with soil properties, climate and elevation data. Using water flow and sand density data as parameters, regional soil erosion load was simulated. A numerical statistical model was used to relate soil erosion to land use and landscape. The results indicated that decadal decrease of grassland areas did not pose a significant threat to soil erosion, while the continual increase of bare land, water area and farmland increased soil erosion. Regional landscape variation also had a strong relationship with erosion. Patch level landscape analyses demonstrated that larger water area led to more soil erosion. The patch correlation indicated that contagious grassland patches reduced soil erosion yield. The increased grassland patches led to more patch edges, in turn increasing the sediment transportation from the patch edges. The findings increase understanding of the temporal variation in soil erosion processes, which is the basis for preventing local pollution.

  16. Demonstrations of LSS active vibration control technology on representative ground-based testbeds

    Science.gov (United States)

    Hyland, David C.; Phillips, Douglas J.; Collins, Emmanuel G., Jr.

    1991-01-01

    This paper describes two experiments which successfully demonstrate control of flexible structures. The first experiment involved control design and implementation for the ACES structure at NASA Marshall Space Flight Center, while the second experiment was conducted using the Multi-Hex Prototype structure. The paper concludes with some remarks on the lessons learned from conducting these experiments.

  17. Instrumentation and process control for fossil demonstration plants. Quarterly technical progress report, January--March 1977

    Energy Technology Data Exchange (ETDEWEB)

    LeSage, L.G.; O' Fallon, N.M.

    1977-09-01

    Progress during the quarter of January through March 1977 on ANL 189a 49622R2, Instrumentation and Process Control for Fossil Demonstration Plants (FDP) is reported. Work has been performed on updating the study of the state-of-the-art of instrumentation for Fossil Demonstration Plants (FDP), on development of mass-flow and other on-line instruments for FDP, process control analysis for FDP, and organization of a symposium on instrumentation and control for FDP. Progress in these areas is described.

  18. Demonstration of active vibration control on a stirling-cycle cryocooler testbed

    Science.gov (United States)

    Johnson, Bruce G.; Flynn, Frederick J.; Gaffney, Monique S.; Johnson, Dean L.; Ross, Ronald G., Jr.

    1992-01-01

    SatCon Technology Corporation has demonstrated excellent vibration reduction performance using active control on the JPL Stirling-cycle cryocooler testbed. The authors address the use of classical narrowband feedback control to meet the cryocooler vibration specifications using one cryocooler in a self-cancellation configuration. Similar vibration reduction performance was obtained using a cryocooler back-to-back configuration by actively controlling a reaction mass actuator that was used to mimic the second cooler.

  19. DEMONSTRATION OF AN ADVANCED INTEGRATED CONTROL SYSTEM FOR SIMULTANEOUS EMISSIONS REDUCTION

    Energy Technology Data Exchange (ETDEWEB)

    Suzanne Shea; Randhir Sehgal; Ilga Celmins; Andrew Maxson

    2002-02-01

    The primary objective of the project titled ''Demonstration of an Advanced Integrated Control System for Simultaneous Emissions Reduction'' was to demonstrate at proof-of-concept scale the use of an online software package, the ''Plant Environmental and Cost Optimization System'' (PECOS), to optimize the operation of coal-fired power plants by economically controlling all emissions simultaneously. It combines physical models, neural networks, and fuzzy logic control to provide both optimal least-cost boiler setpoints to the boiler operators in the control room, as well as optimal coal blending recommendations designed to reduce fuel costs and fuel-related derates. The goal of the project was to demonstrate that use of PECOS would enable coal-fired power plants to make more economic use of U.S. coals while reducing emissions.

  20. Climatically controlled increase in Quaternary erosion rates: An exploration of real and perceived biases from thermochronology data

    Science.gov (United States)

    van der Beek, Peter; Schildgen, Taylor

    2017-04-01

    The potential increase of erosion rates over the last few million years in response to climate change and Quaternary glaciations remains controversial. Such an increase was initially inferred from the sedimentary record, but several authors have argued that this record is biased due to unresolved erosional hiatuses, and therefore the inferred increase in sedimentation rates is an artefact. More recently, the discussion has focused on erosional records from the source areas themselves; in particular records extracted from low-temperature thermochronology data. A global compilation of such data appears to show increasing erosion rates toward the present, but it has been argued that this increase may also be an artefact, for similar reasons that affect the sedimentary record. Here we assess real and perceived biases in the thermochronological record that might affect the inference of temporal variations in erosion rates from such data. We argue that it is unlikely that erosional hiatuses affect thermochronology data because the temporal and spatial scales at which such hiatuses might occur are significantly smaller than those that are resolved by the data. Instead, we explore the potential bias introduced by the erosional response time of thermochronological systems (defined as the time required to exhume rocks that are fully reset for the thermochronological system considered, i.e. to attain exhumational steady state). These response times are typically longer than the timescale of Quaternary glacial-interglacial cycles, implying that thermochronological systems are insensitive to such variations. For thermochronological data to record an overall increase in erosion rates, the increase must occur over longer time periods, independent of superimposed shorter-term variations. However, because the erosional response times depend strongly on the final exhumation rate, it is much easier to detect increases in erosion rates with thermochronological data than to detect

  1. Riverbank erosion induced by gravel bar accretion

    Science.gov (United States)

    Klösch, Mario; Habersack, Helmut

    2010-05-01

    Riverbank erosion is known to be strongly fluvially controlled and determination of shear stresses at the bank surface and at the bank toe is a crucial point in bank erosion modeling. In many modeling attempts hydraulics are simulated separately in a hydrodynamic-numerical model and the simulated shear stresses are further applied onto the bank surface in a bank erosion model. Hydrodynamics are usually simulated at a constant geometry. However, in some cases bed geometry may vary strongly during the event, changing the conditions for hydrodynamics along the bank. This research seeks to investigate the effect of gravel bar accretion during high discharges on final bank retreat. At a restored section of the Drava River bed widenings have been implemented to counter bed degradation. There, in an initiated side-arm, self-dynamic widening strongly affects bed development and long-term connectivity to the main channel. Understanding the riverbank erosion processes there would help to improve planning of future restoration measures. At one riverbank section in the side-arm large bank retreat was measured repeatedly after several flow events. This section is situated between two groins with a distance of 60 m, which act as lateral boundaries to the self-widening channel. In front of this bank section a gravel bar developed. During low flow condition most discharge of the side-arm flows beside the gravel bar along the bank, but shear stresses are too low for triggering bank erosion. For higher discharges results from a two-dimensional hydrodynamic-numerical model suggested shear stresses there to be generally low during the entire events. At some discharges the modeled flow velocities even showed to be recirculating along the bank. These results didn't explain the observed bank retreat. Based on the modeled shear stresses, bank erosion models would have greatly underestimated the bank retreat induced by the investigated events. Repeated surveys after events applying

  2. A preliminary study on vegetation-erosion dynamics and its applications

    Institute of Scientific and Technical Information of China (English)

    WANG; Zhaoyin; WANG; Guangqian; LI; Changzhi

    2005-01-01

    Vegetation-erosion dynamics is a new interdisciplinary science, studying the laws of evolution of watershed vegetation under the action of various ecological stresses. Introducing a qualitative expression of ecological stresses in this paper, the present authors establish the coupled differential equations for the vegetation-erosion process and derive a theoretical solution. The model is applied to the Anjiagou watershed on the Loess Pateau and the Xiaojiang watershed and its sub-watersheds on the Yunnan Plateau. The calculated results agree well with the vegetation development processes. Abstracted from the differential equations the so-called vegetation-erosion chart is worked out, with which we can predict the development trend of vegetation under no human stresses. It is demonstrated that the erosion control is important for vegetation development and reforestation must be a long-term strategy. On the Yunnan Plateau with relatively high precipitation and temperature, vegetation can be greatly improved if erosion is controlled. On the dry and cold Loess Pateau suffering from high rate of soil erosion, however, vegetation can effectively control erosion but erosion reduction exhibits low effectiveness on vegetation development. Vegetation in the area is not stable and management is always needed to maintain the vegetation.

  3. Turbine Engine Control Synthesis. Volume 1. Optimal Controller Synthesis and Demonstration

    Science.gov (United States)

    1975-03-01

    stability. rolume 11 contains three Appendices. Appendix A contains the details of engine math models. The software for the wind tu reel -ontroller is...aspects of optimal control. Volume II contains primarily data concerning the NASA component engine model and software for the wind tunnel test con...PTPB.NRTTB,6) Turbine FN 275 WT WTTNPB N * PB/TB 276 PBDLTB = PB (TB - TCD) 277 ETAB - FUNI(19, PBDLTB, 35) Combustion efficiency 278 CALL PROCOM (0

  4. Evaluation of Rhizobium tropici-derived Biopolymer for Erosion Control of Protective Berms. Field Study: Iowa Army Ammunition Plant

    Science.gov (United States)

    2016-06-01

    of the berm that channeled runoff water into the area of the slip. Slope stabilization using biopolymer is approximately half the cost of...resources. When wetted, the biopolymer will form a gel within the soil matrix. With the soil acting as a buffer, the ionic character of the polymer...detailed view of the weathered West face of the berm. The red color indicates soil loss, marking the creation of erosion channels across the face

  5. Innovative In-Situ Remediation of Contaminated Sediments for Simultaneous Control of Contamination and Erosion. Part 2

    Science.gov (United States)

    2011-10-01

    mixtures of amendments (i.e., MAACs) compared with single amendment formulations. Bentonite is a clay material primarily composed of montmorillonite...a member of the smectite family of clay minerals. Bentonite is the most cohesive of the common clays , and has the greatest effect on erosion rates...zeolite, and clay . The results showed that phosphate, zeolite, bentonite , and organoclays individually or mixed with another active or neutral

  6. DA-9601 for erosive gastritis:Results of a double-blind placebo-controlled phase Ⅲ clinical trial

    Institute of Scientific and Technical Information of China (English)

    Sang Yong Seol; Myung Hwan Kim; Jong Sun Ryu; Myung Gyu Choi; Dong Wook Shin; Byoung Ok Ahn

    2004-01-01

    AIM: To determine the efficacy and safety of DA-9601 on erosive gastritis versus cetraxate as a standard drug by gastrointestinal endoscopy.METHODS: Five hundred and twelve patients with erosive gastritis were divided into three groups. The groups received 180 mg or 360 mg of DA-9601, or 600 mg of cetraxate (NeuerTM) t.i.d, for 2 wk, respectively. Endoscopic observations were performed before and 2 wk after the treatment, and the cure and improvement rates were investigated.RESULTS: Of the 512 intention-to-treat (ITl) population,457 patients comprised the per protocol (PP) analysis.Endoscopic cure rate was significantly higher in the DA9601 group than in the cetraxate group in both the PP (56%, 58% vs36%; DA-9601 180 mg, 360 mg and cetraxate,respectively) and ITT (52%, 51% vs 35%) populations.Two DA-9601 groups (180 and 360 mg) had significantly higher endoscopic improvement rates than the cetraxate group in both the PP (67%, 65% vs 46%) and ITT (63%,58% vs 45%) populations. The percentage of symptom relief over the 2 wk was found not significantly different between groups. During the study, both DA-9601 and cetraxate produced no treatment-associated adverse events.CONCLUSION: From these results, it appears that DA9601 has excellent efficacy on erosive gastritis. This study also confirms the safety profile of DA-9601.

  7. A case for wind enhanced tectonics: Plio-Quaternary sedimentation, erosion, and structural evolution controlled by wind within the Qaidam Basin, China

    Science.gov (United States)

    Heermance, R. V.; Kapp, P. A.; Pullen, A.; Garzione, C. N.

    2012-12-01

    The interplay between tectonics and localized erosion through fluvial and/or glacial processes has been widely documented. Wind erosion, however, has gone largely un-recognized as a potentially important process in this concept. We document an acceleration in shortening in response to wind deflation above actively deforming fault propagation anticlines since ~3.0 Ma in the Qaidam Basin, China. Evidence for this comes from a 1750 m measured section along the southwestern flank of an intra-basin anticline (38.33°N, 93.46°E) and regional cross-sections. Magnetostratigraphy provides age control for prominent stratigraphic and isotopic changes within the section. A positive shift of ~6‰ in the δ18O values of lake carbonates occurs at 1090 m (3.1 Ma), interpreted to be the result of increased aridity at that time. An intraformational angular unconformity, associated with anticline growth, appears at 1172 m (3.0 Ma) and records the initiation of growth strata deposition. At 1235 m (2.6 Ma), a marked lithofacies change to sub-aerial, evaporitic conditions is observed, and is associated with a 3-fold reduction in sedimentation rate. Paleo-yardangs, which are wind-eroded landforms preserved in the stratigraphic record, appear at 1260 m (2.4 Ma). These observations indicate that regional aridification at 3.1 Ma was followed closely by or coincident with fold growth. Facies changes to more evaporitic strata and erosion of the basin floor (based on paleo-yardangs) trailed initial climate and tectonic changes by 500,000-700,000 years. Although the on-lap relationship of post-growth strata implies that syn-tectonic strata may have pinched-out along the flanks of the anticline, our new analysis indicates that at least 1172 m of pre-growth strata must have been eroded from the core of the anticline since 3.0 Ma at a time-averaged rate of ~0.4 mm/year, comparable to fluvial and glacial erosion rates within active tectonic settings. The lack of an integrated fluvial channel

  8. Proceedings of the 1978 symposium on instrumentation and control for fossil demonstration plants

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-01

    The 1978 symposium on instrumentation and control for fossil demonstration plants was held at Newport Beach, California, June 19--21, 1978. It was sponsored by Argonne National Laboratory, the U.S. Department of Energy - Fossil Energy, and the Instrument Society of America - Orange County Section. Thirty-nine papers have been entered individually into the data base. (LTN)

  9. Demonstrating multi-layered MAS in control of offshore oil and gas production

    DEFF Research Database (Denmark)

    Lindegaard Mikkelsen, Lars; Næumann, J. R.; Demazeau, Y.

    2013-01-01

    From a control perspective, offshore oil and gas production is very challenging due to the many and potentially conflicting production objectives that arise from the intrinsic complexity of the oil and gas domain. In this paper, we demonstrate how a multi-layered multi-agent system can be used...

  10. A Comparison of Types of Robot Control for Programming by Demonstration

    DEFF Research Database (Denmark)

    Fischer, Kerstin; Kirstein, Franziska; Jensen, Lars Christian

    2016-01-01

    Programming by Demonstration (PbD) is an efficient way for non-experts to teach new skills to a robot. PbD can be carried out in different ways, for instance, by kinesthetic guidance, teleoperation or by using external controls. In this paper, we compare these three ways of controlling a robot...... in terms of efficiency, effectiveness (success and error rate) and usability. In an industrial assembly scenario, 51 participants carried out pegin- hole tasks using one of the three control modalities. The results show that kinesthetic guidance produces the best results. In order to test whether...

  11. A Research Framework for Demonstrating Benefits of Advanced Control Room Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Le Blanc, Katya [Idaho National Lab. (INL), Idaho Falls, ID (United States); Boring, Ronald [Idaho National Lab. (INL), Idaho Falls, ID (United States); Joe, Jeffrey [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hallbert, Bruce [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thomas, Kenneth [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-12-01

    Control Room modernization is an important part of life extension for the existing light water reactor fleet. None of the 99 currently operating commercial nuclear power plants in the U.S. has completed a full-scale control room modernization to date. A full-scale modernization might, for example, entail replacement of all analog panels with digital workstations. Such modernizations have been undertaken successfully in upgrades in Europe and Asia, but the U.S. has yet to undertake a control room upgrade of this magnitude. Instead, nuclear power plant main control rooms for the existing commercial reactor fleet remain significantly analog, with only limited digital modernizations. Previous research under the U.S. Department of Energy’s Light Water Reactor Sustainability Program has helped establish a systematic process for control room upgrades that support the transition to a hybrid control. While the guidance developed to date helps streamline the process of modernization and reduce costs and uncertainty associated with introducing digital control technologies into an existing control room, these upgrades do not achieve the full potential of newer technologies that might otherwise enhance plant and operator performance. The aim of the control room benefits research presented here is to identify previously overlooked benefits of modernization, identify candidate technologies that may facilitate such benefits, and demonstrate these technologies through human factors research. This report serves as an outline for planned research on the benefits of greater modernization in the main control rooms of nuclear power plants.

  12. Demonstration of Intelligent Control and Fan Improvements in Computer Room Air Handlers

    Energy Technology Data Exchange (ETDEWEB)

    Coles, Henry [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division; Greenberg, Steve [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division; Vita, Corinne [Vigilent, Oakland, CA (United States)

    2012-11-30

    This report documents a demonstration of the energy-efficiency improvement provided by a new control system for computer room air handling devices. It also analyzes measured and reported air handling device fan power associated with changing the fan type. A 135,000 square foot commercial data center was used for the demonstration. All air handling units were upgraded with improved efficiency fans, and a control system that automatically adjusts the fan speed for the air handling units was added. Power measurements were collected for a baseline and for a period with the fan speed control system active. Changing the fan type resulted in a savings of 47 percent of energy used by the air handling equipment and associated chiller plant energy needed to cool the air handlers themselves. The addition of the fan speed control resulted in an additional 37 percent savings in the same two categories. The combined savings for the two improvements for the same categories was 66 percent compared to the data center fitted with the original fans without a control system. The energy use reduction provided by the complete air handling device improvement program for the whole data center site is estimated to be 2.9 million kilowatt hours per year—an overall data center site savings of 8.0 percent. The reduced electrical energy use at the site provides a 1.9 million pound yearly reduction of carbon dioxide emissions. This demonstration showed that fan upgrades and a control system addition provide cost-effective improvements for data centers, with a payback reported to be under two years without utility incentives. In addition to the control system providing energy savings, the data collection and visual analysis capabilities provided immediate and long-term benefits. It is recommended that data center operators consider investing in fan upgrades and/or adding fan speed control for computer room air handlers.

  13. SpaceWire- Based Control System Architecture for the Lightweight Advanced Robotic Arm Demonstrator [LARAD

    Science.gov (United States)

    Rucinski, Marek; Coates, Adam; Montano, Giuseppe; Allouis, Elie; Jameux, David

    2015-09-01

    The Lightweight Advanced Robotic Arm Demonstrator (LARAD) is a state-of-the-art, two-meter long robotic arm for planetary surface exploration currently being developed by a UK consortium led by Airbus Defence and Space Ltd under contract to the UK Space Agency (CREST-2 programme). LARAD has a modular design, which allows for experimentation with different electronics and control software. The control system architecture includes the on-board computer, control software and firmware, and the communication infrastructure (e.g. data links, switches) connecting on-board computer(s), sensors, actuators and the end-effector. The purpose of the control system is to operate the arm according to pre-defined performance requirements, monitoring its behaviour in real-time and performing safing/recovery actions in case of faults. This paper reports on the results of a recent study about the feasibility of the development and integration of a novel control system architecture for LARAD fully based on the SpaceWire protocol. The current control system architecture is based on the combination of two communication protocols, Ethernet and CAN. The new SpaceWire-based control system will allow for improved monitoring and telecommanding performance thanks to higher communication data rate, allowing for the adoption of advanced control schemes, potentially based on multiple vision sensors, and for the handling of sophisticated end-effectors that require fine control, such as science payloads or robotic hands.

  14. Advanced Grid-Friendly Controls Demonstration Project for Utility-Scale PV Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Gevorgian, Vahan [National Renewable Energy Lab. (NREL), Golden, CO (United States); O' Neill, Barbara [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-01-21

    A typical photovoltaic (PV) power plant consists of multiple power electronic inverters and can contribute to grid stability and reliability through sophisticated 'grid-friendly' controls. The availability and dissemination of actual test data showing the viability of advanced utility-scale PV controls among all industry stakeholders can leverage PV's value from being simply an energy resource to providing additional ancillary services that range from variability smoothing and frequency regulation to power quality. Strategically partnering with a selected utility and/or PV power plant operator is a key condition for a successful demonstration project. The U.S. Department of Energy's (DOE's) Solar Energy Technologies Office selected the National Renewable Energy Laboratory (NREL) to be a principal investigator in a two-year project with goals to (1) identify a potential partner(s), (2) develop a detailed scope of work and test plan for a field project to demonstrate the gird-friendly capabilities of utility-scale PV power plants, (3) facilitate conducting actual demonstration tests, and (4) disseminate test results among industry stakeholders via a joint NREL/DOE publication and participation in relevant technical conferences. The project implementation took place in FY 2014 and FY 2015. In FY14, NREL established collaborations with AES and First Solar Electric, LLC, to conduct demonstration testing on their utility-scale PV power plants in Puerto Rico and Texas, respectively, and developed test plans for each partner. Both Puerto Rico Electric Power Authority and the Electric Reliability Council of Texas expressed interest in this project because of the importance of such advanced controls for the reliable operation of their power systems under high penetration levels of variable renewable generation. During FY15, testing was completed on both plants, and a large amount of test data was produced and analyzed that demonstrates the ability of

  15. Graffiti for science - erosion painting reveals spatially variable erosivity of sediment-laden flows

    Science.gov (United States)

    Beer, Alexander R.; Kirchner, James W.; Turowski, Jens M.

    2016-12-01

    Spatially distributed detection of bedrock erosion is a long-standing challenge. Here we show how the spatial distribution of surface erosion can be visualized and analysed by observing the erosion of paint from natural bedrock surfaces. If the paint is evenly applied, it creates a surface with relatively uniform erodibility, such that spatial variability in the erosion of the paint reflects variations in the erosivity of the flow and its entrained sediment. In a proof-of-concept study, this approach provided direct visual verification that sediment impacts were focused on upstream-facing surfaces in a natural bedrock gorge. Further, erosion painting demonstrated strong cross-stream variations in bedrock erosion, even in the relatively narrow (5 m wide) gorge that we studied. The left side of the gorge experienced high sediment throughput with abundant lateral erosion on the painted wall up to 80 cm above the bed, but the right side of the gorge only showed a narrow erosion band 15-40 cm above the bed, likely due to deposited sediment shielding the lower part of the wall. This erosion pattern therefore reveals spatial stream bed aggradation that occurs during flood events in this channel. The erosion painting method provides a simple technique for mapping sediment impact intensities and qualitatively observing spatially distributed erosion in bedrock stream reaches. It can potentially find wide application in both laboratory and field studies.

  16. EPro Non-contact erosion profiling

    DEFF Research Database (Denmark)

    Meinert, Palle

    EPro is a profiler controlled by software, which is constructed to measure the same surface or work piece multiple times and track changes due to erosion.......EPro is a profiler controlled by software, which is constructed to measure the same surface or work piece multiple times and track changes due to erosion....

  17. Erosion of quantitative host resistance in the apple × Venturia inaequalis pathosystem

    NARCIS (Netherlands)

    Caffier, V.; Lasserre-Zuber, P.; Giraud, M.; Lascostes, M.; Sievenard, R.; LeMarquand, A.; Weg, van de W.E.; Expert, P.; Denancé, C.

    2014-01-01

    Theoretical approaches predict that host quantitative resistance selects for pathogens with a high level of pathogenicity, leading to erosion of the resistance. This process of erosion has, however, rarely been experimentally demonstrated. To investigate the erosion of apple quantitative resistance

  18. Particulate Loads Caused by Wind Erosion in the Great Plains

    Science.gov (United States)

    Hagen, Lawrence J.; Woodruff, Neil P.

    1975-01-01

    In this paper the annual flux of suspended particulates caused by wind erosion in the Great Plains is estimated. This study demonstrated that climate causes wide variations in air pollution from wind erosion. (BT)

  19. Instrumentation and process control for fossil demonstration plants. Quarterly technical progress report, April--June 1977

    Energy Technology Data Exchange (ETDEWEB)

    LeSage, L.G.

    1977-07-01

    Work has been performed on updating the study of the state-of-the-art of instrumentation for Fossil Demonstration Plants (FDP), development of mass-flow and other on-line instruments for FDP, process control analysis for FDP, and organization of a symposium on instrumentation and control for FDP. A Solids/Gas Flow Test Facility (S/GFTF) under construction for instrument development, testing, evaluation, and calibration is described. The development work for several mass-flow and other on-line instruments is described: acoustic flowmeter, capacitive density flowmeter, neutron activation flowmeter and composition analysis system, gamma ray correlation flowmeter, optical flowmeter, and capacitive liquid interface level meter.

  20. Experimental Investigation and Analytical Modeling of Solid-Particle Erosion Behavior of Stellite Alloys

    Science.gov (United States)

    Nsoesie, Sydney

    Stellite alloys are a range of cobalt-chromium alloys, also containing tungsten or molybdenum and a small amount (corrosion, wear and erosion environments. In this research a group of Stellite alloys that are commonly employed or potentially materials for erosion resistance application are studied under solid-particle erosion test. Two particle impact velocities (84 m/s and 98 m/s) and two impingement angles (30 degree and 90 degree) are used in the test. It is demonstrated that Stellite alloys are more resistant to erosion at 90 degree impingement angle than at 30 degree impingement angle and the erosion damage of Stellite alloys increases with the particle impact velocity. The erosion resistance of Stellite alloys is controlled mainly by their carbon content, but the tungsten and molybdenum contents also play an important role, because these elements determine the volume fractions of carbides and intermetallics in Stellite alloys. The eroded surfaces are analyzed using SEM to further understand the erosion test results. An erosion model, originally developed by Sheldon and Kanhere (1972), known as S-K model, has been modified for use on Stellite alloys, with the support of experimental data. The significant contribution of this modification is that the effect of particle impingement angle has been included. With this modified S-K model, for a Stellite alloy that has a similar chemical composition to one of the alloys studied in this research, the erosion rate for a set particle impact, velocity at an impingement angle between 30 degree and 90 degree can, be estimated. This modified S-K model can be used for erosion characterization of existing Stellite alloys and in the designing of new Stellite alloys for erosion resistance application.

  1. Proceedings of the 1977 symposium on instrumentation and process control for fossil demonstration plants

    Energy Technology Data Exchange (ETDEWEB)

    1977-01-01

    The 1977 Symposium on Instrumentation and Process Control for Fossil Demonstration Plants was held at Hyatt Regency O'Hare, Chicago, Illinois, July 13 to 15, 1977. It was sponsored by the Argonne National Laboratory, the U.S. Energy Research and Development Administration and the Instrument Society of America (Chicago Section). Seventeen papers from thee proceedings were entered individually into EDB and ERA (three papers weree entered previously). (LTN)

  2. Interactive remote control for an STS-based superfluid helium transfer demonstration

    Science.gov (United States)

    Shapiro, Jeff C.; Robinson, Frank A.

    1989-01-01

    NASA's superfluid helium on-orbit transfer (SHOOT) experiment, which is a Shuttle-based demonstration of the technology required to service cryogenically cooled satellites in space, is described. The SHOOT Command and Monitoring System software, developed on Macintosh II, will provide a near-real-time highly interactive interface making it possible to control the experiment and to analyze and display its telemetry. User interface is discussed as well as conversion functions, and hardware.

  3. MRI of the wrist in juvenile idiopathic arthritis: erosions or normal variants? A prospective case-control study

    Energy Technology Data Exchange (ETDEWEB)

    Ording Muller, Lil-Sofie [University Hospital North Norway, Department of Radiology, Tromsoe (Norway); Great Ormond Street Hospital for Children, Department of Radiology, London (United Kingdom); Boavida, Peter [Homerton University Hospital, Department of Radiology, London (United Kingdom); Avenarius, Derk; Eldevik, Odd Petter [University Hospital North Norway, Department of Radiology, Tromsoe (Norway); Damasio, Beatrice [Ospedale Pediatrico Gaslini, Department of Radiology, Genoa (Italy); Malattia, Clara [Ospedale Pediatrico Gaslini, Department of Rhematology, Genoa (Italy); Lambot-Juhan, Karen [Hopital Necker Enfants Malades, Department of Radiology, Paris (France); Tanturri, Laura [Ospedale Pediatrico Bambino Gesu, Department of Radiology, Rome (Italy); Owens, Catherine M. [Great Ormond Street Hospital for Children, Department of Radiology, London (United Kingdom); UCL, Institute of Child Health, London (United Kingdom); Rosendahl, Karen [Great Ormond Street Hospital for Children, Department of Radiology, London (United Kingdom); UCL, Institute of Child Health, London (United Kingdom); Haukeland University Hospital, Department of Radiology, Bergen (Norway); University of Bergen, Department of Surgical Sciences, Bergen (Norway)

    2013-07-15

    Bony depressions at the wrist resembling erosions are frequently seen on MRI in healthy children. The accuracy of MRI in detecting early bony destruction is therefore questionable. We compared findings on MRI of the wrist in healthy children and those with juvenile idiopathic arthritis (JIA) to investigate markers for true disease. We compared the number and localisation of bony depressions at the wrist in 85 healthy children and 68 children with JIA, ages 5-15 years. The size of the wrist was assessed from a radiograph of the wrist performed on the same day as the MRI. No significant difference in the number of bony depressions in the carpal bones was seen between healthy children and children with JIA at any age. Depressions are found in similar locations in the two groups, except for a few sites, where bony depressions were seen exclusively in the JIA group, particularly at the CMC joints. The wrist was significantly smaller in children with JIA (P < 0.001). Using adult scoring systems and standard MR sequences in the assessment of bone destruction in children may lead to overstaging or understaging of disease. At present, standard MRI sequences cannot easily be used for assessment of early signs of erosions in children. (orig.)

  4. Instrumentation and process control for fossil demonstration plants. Annual technical progress report, October 1976--September 1977

    Energy Technology Data Exchange (ETDEWEB)

    LeSage, L. G.; O' Fallon, N. M.

    1977-10-01

    Progress on Instrumentation and Process Control for Fossil Demonstration Plants (FDP) is reported. Work has been performed on updating the study of the state-of-the-art of instrumentation for FDP, development of mass-flow and other on-line instruments for FDP, process control analysis for FDP, and organization of a symposium on instrumentation and control for FDP. A Solids/Gas Flow Test Facility (S/GFTF) under construction for instrument development, testing, evaluation, and calibration is described. The development work for several mass-flow and other on-line instruments is described: acoustic flowmeter, capacitive density flowmeter, neutron activation flowmeter, gamma ray correlation flowmeter, optical flowmeter, composition analysis system, and capacitive liquid interface level meter.

  5. Proof-of-Concept Demonstration Results for Robotic Visual Servo Controllers

    Energy Technology Data Exchange (ETDEWEB)

    Chawda, P.V.

    2004-09-22

    There is significant motivation to provide robotic systems with improved autonomy as a means to significantly accelerate deactivation and decommissioning operations while also reducing the associated costs, removing human operators from hazardous environments, and reducing the required burden and skill of human operators. To achieve improved autonomy, fundamental research is focused on the challenges of developing visual servo controllers. The challenge in developing these controllers is that a camera provides 2-dimensional image information about the 3-dimensional Euclidean-space through a perspective (range dependent) projection that can be corrupted by uncertainty in the camera calibration matrix. Disturbances in this relationship (i.e., corruption in the sensor information) propagate erroneous information to the feedback controller of the robot, leading to potentially unpredictable task execution. This technical manual describes 3 proof-of-concept demonstrations of visual servo controllers developed from fundamental research aimed at these challenges. Specifically, one section describes the implementation of a cooperative visual servo control scheme with a camera-in-hand and a fixed camera to track a moving target despite uncertainty in the camera calibration and the unknown constant distance from the camera to a target where the camera is mounted on the end-effector of a 6 degrees-of-freedom hydraulic robot manipulator. The next section describes the implementation of 2 homography-based visual servo tracking and regulation controllers for a mobile robot with a calibrated camera despite an unknown time-varying distance from the camera to a target.

  6. Demonstration of a Low-Lift Heat Pump for High-Power Spacecraft Thermal Control

    Science.gov (United States)

    Grzyll, Lawrence R.

    2006-01-01

    This paper describes the development and demonstration of a prototype low-lift heat pump for high-power spacecraft thermal control The low-lift heat pump was designed to provide 25 kW of cooling at 303 K and transport this waste heat to a radiator for heat rejection. To accomplish this, a demonstration heat pump with an evaporation temperature of 298 K and a condensing temperature of 301 K was designed and built. HFC-227ea was the working fluid. This effort resulted in optimization of the centrifugal compressor impeller, diffuser, and shroud designs through extensive experimental testing. The detailed design of a magnetic bearing centrifugal compressor was completed. A prototype heat pump thermal control system was designed and fabricated which contained prototypical cold plate and condenser designs. This prototype system was extensively tested and demonstrated to measure performance parameters such as power consumption, cooling capacity, system size and mass, and other key parameters. Finally, the experimental performance was input into the theoretical trade study allowing for a comparison of the actual performance of the low-lift heat pump to a single-phase pumped loop. Inputting the experimental low-lift heat pump performance into the trade study showed that the low-lift heat pump still has lower system mass than the single-phase pumped loop for all space temperatures considered. The experimental results very closely match the theoretical results used in the trade study.

  7. Development and demonstration of optical polarization controller; Hikari henpa seigyo sochi no kaihatsu to jissho

    Energy Technology Data Exchange (ETDEWEB)

    Kurono, M. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

    1997-04-01

    If fiber transmission light can be controlled in a stabilized polarization state, realization of coherent optical communication is anticipated. In the case of adopting it to OPGW, however, it is necessary to compensate high speed polarization variation caused by lightning strike. But this was difficult in the conventional method. Accordingly, a high speed polarization control method was proposed which uses an electric effect of lithium niobate (LN) crystals. In the study, a polarization control unit was manufactured based on the method proposed and the performance was demonstrated. As a result of measuring output light with input light changed in every state of polarization, the object horizontal polarization component obtained a stabilized light intensity at {+-}0.1dB, and a light intensity of the component slipped out of the horizontal polarization was suppressed under -20dB. To cope with the polarization variation by lightning strike, it is necessary to make the control delay 10{mu}sec or below, and improvement in processing unit, etc. may make it possible since LN crystals respond below 1{mu}sec. High speed control of the infinitely continuing arbitrary polarization variation became possible. 14 refs., 19 figs.

  8. Beyond the "hot-and-cold" game: a demonstration of computer-controlled shaping.

    Science.gov (United States)

    Silva, F J

    1999-02-01

    Shaping, or the method of successive approximations, is widely taught in introductory psychology and the psychology of learning as a procedure for establishing new behavior. This article illustrates a computer-controlled shaping demonstration that allows the user to specify several critical parameters of the shaping process and that then shapes the user's mouse movements toward an arbitrary virtual (invisible) target on the computer screen. The relative effectiveness of different shaping parameters can be assessed by examining several dependent measures, such as the distance of the cursor from the target across time and the rate at which reinforcers were earned. This demonstration allows students to move beyond the notion that shaping is simply the application of the "hot-and-cold" game and to understand that there is a science underlying the art of shaping.

  9. Integrated Power and Attitude Control System Demonstrated With Flywheels G2 and D1

    Science.gov (United States)

    Jansen, Ralph H.

    2005-01-01

    On September 14, 2004, NASA Glenn Research Center's Flywheel Development Team experimentally demonstrated a full-power, high-speed, two-flywheel system, simultaneously regulating a power bus and providing a commanded output torque. Operation- and power-mode transitions were demonstrated up to 2000 W in charge and 1100 W in discharge, while the output torque was simultaneously regulated between plus or minus 0.8 N-m. The G2 and D1 flywheels--magnetically levitated carbon-fiber wheels with permanent magnet motors--were used for the experiment. The units were mounted on an air bearing table in Glenn's High Energy Flywheel Facility. The operational speed range for these tests was between 20,000 and 60,000 rpm. The bus voltage was regulated at 125 V during charge and discharge, and charge-discharge and discharge-charge transitions were demonstrated by changing the amount of power that the power supply provided between 300 and 0 W. In a satellite system, this would be the equivalent of changing the amount of energy that the solar array provides to the spacecraft. In addition to regulating the bus voltage, we simultaneously controlled the net torque produced by the two flywheel modules. Both modules were mounted on an air table that was restrained by a load cell. The load cell measured the force on the table, and the torque produced by the two flywheels on the table could be calculated from that measurement. This method was used to measure the torque produced by the modules, yielding net torques from -0.8 to 0.8 N-m. This was the first Glenn demonstration of the Integrated Power and Attitude Control System (IPACS) at high power levels and speeds.

  10. Erosion and Errors

    NARCIS (Netherlands)

    Huisman, H.; Heeres, Glenn; Os, van Bertil; Derickx, Willem; Schoorl, J.M.

    2016-01-01

    Slope soil erosion is one of the main threats to archaeological sites. Several methods were applied to establish the erosion rates at archaeological sites. Digital elevation models (DEMs) from three different dates were used. We compared the elevations from these three models to estimate erosion. We

  11. Flywheel Single-Axis Integrated Momentum and Power Control System Demonstrated

    Science.gov (United States)

    Soeder, James F.

    2004-01-01

    On July 10, 2003, the NASA Glenn Research Center flywheel team experimentally demonstrated a two-flywheel-module system that simultaneously provided attitude control in a single axis and regulated power. The test was conducted using the D1 flywheel module and the high-speed shaft (HSS) in the High Energy Flywheel Facility (HEFF). Both of these flywheel modules consist of a magnetically levitated rotor with an integral motor/generator, a vacuum housing, and mechanical touchdown bearings. Energy is stored kinetically in the rotor. The motor/generator allows energy to be added to or withdrawn from the rotor, and magnetic bearings and a vacuum enclosure are used to minimize losses.

  12. Hanford Waste Vitrification Plant technical background document for best available radionuclide control technology demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, A.B.; Skone, S.S.; Rodenhizer, D.G.; Marusich, M.V. (Ebasco Services, Inc., Bellevue, WA (USA))

    1990-10-01

    This report provides the background documentation to support applications for approval to construct and operate new radionuclide emission sources at the Hanford Waste Vitrification Plant (HWVP) near Richland, Washington. The HWVP is required to obtain permits under federal and state statutes for atmospheric discharges of radionuclides. Since these permits must be issued prior to construction of the facility, draft permit applications are being prepared, as well as documentation to support these permits. This report addresses the applicable requirements and demonstrates that the preferred design meets energy, environmental, and economic criteria for Best Available Radionuclide Control Technology (BARCT) at HWVP. 22 refs., 11 figs., 25 tabs.

  13. Demonstration of a quantum controlled-NOT gate in the telecommunications band.

    Science.gov (United States)

    Chen, Jun; Altepeter, Joseph B; Medic, Milja; Lee, Kim Fook; Gokden, Burc; Hadfield, Robert H; Nam, Sae Woo; Kumar, Prem

    2008-04-04

    We present the first quantum controlled-not (cnot) gate realized using a fiber-based indistinguishable photon-pair source in the 1.55 microm telecommunications band. Using this free-space cnot gate, all four Bell states are produced and fully characterized by performing quantum-state tomography, demonstrating the gate's unambiguous entangling capability and high fidelity. Telecom-band operation makes this cnot gate particularly suitable for quantum-information-processing tasks that are at the interface of quantum communication and linear optical quantum computing.

  14. INVESTIGATION AND DEMONSTRATION OF DRY CARBON-BASED SORBENT INJECTION FOR MERCURY CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    Terry Hunt; Mark Fox; Lillian Stan; Sheila Haythornthwaite; Justin Smith; Jason Ruhl

    1998-10-01

    This quarterly report describes the activities that have taken place during the first full quarter of the Phase II project ''Investigation and Demonstration of Dry Carbon-Based Sorbent Injection for Mercury Control''. Modifications were completed and sampling began at the 600 acfm pilot-scale particulate control module (PCM) located at the Comanche Station in Pueblo, CO. The PCM was configured as an electrostatic precipitator for these tests. A Perkin-Elmer flue gas mercury analyzer was installed on-site and operated. Initial test results using both manual sampling methodology and the mercury analyzer are presented herein. Preparations were made during this period for full-scale mercury testing of several PSCo units. A site visit was made to Arapahoe and Cherokee Generating Stations to determine sample locations and to develop a test plan.

  15. Demonstration of a Controlled-Phase Gate for Continuous-Variable One-Way Quantum Computation

    CERN Document Server

    Ukai, Ryuji; Yoshikawa, Jun-ichi; van Loock, Peter; Furusawa, Akira

    2011-01-01

    We experimentally demonstrate a controlled-phase gate for continuous variables in a fully measurement-based fashion. In our scheme, the two independent input states of the gate, encoded in two optical modes, are teleported into a four-mode Gaussian cluster state. As a result, one of the entanglement links present in the initial cluster state appears in the two unmeasured output modes as the corresponding entangling gate acting on the input states. The genuine quantum character of this gate becomes manifest and is verified through the presence of entanglement at the output for a product two-mode coherent input state. By combining our controlled-phase gate with the recently reported module for universal single-mode Gaussian operations [R. Ukai et al., Phys. Rev. Lett. 106, 240504 (2011)], it is possible to implement universal Gaussian operations on arbitrary multi-mode quantum optical states in form of a fully measurement-based one-way quantum computation.

  16. A comparative study of toluidine blue-mediated photodynamic therapy versus topical corticosteroids in the treatment of erosive-atrophic oral lichen planus: a randomized clinical controlled trial.

    Science.gov (United States)

    Jajarm, Hasan Hoseinpour; Falaki, Farnaz; Sanatkhani, Majid; Ahmadzadeh, Meysam; Ahrari, Farzaneh; Shafaee, Hooman

    2015-07-01

    Recently, photodynamic therapy (PDT) has been suggested as a new treatment option that is free from side effects for erosive-atrophic oral lichen planus (OLP). The purpose of this study was to compare the effect of toluidine blue-mediated photodynamic therapy (TB-PDT) with local corticosteroids on treatment of erosive-atrophic OLP. In this randomized clinical trial, 25 patients with keratotic-atrophic-erosive oral lichen planus were allocated randomly into two groups. Group 1 (experimental): topical application of toluidine blue with micropipette was applied, and after 10 min, the patients were treated with a 630-nm GaAlAs laser (power density: 10 mW/cm(2)) during two visits. Group 2 (control) used mouthwash diluted with dexamethasone (tab 0/5 in 5 ml water) for 5 min, and then, it was spat out, and after 30 min, the mouth was rinsed with 30 drops of nystatin 100,000 units for 5 min and again spat out. Demographic data, type, and severity of the lesions and pain were recorded before and after treatment and then at the 1-month follow-up visit. Response rate was defined based on changes in intensity of the lesions and pain. In the experimental and control groups, sign scores of changes significantly reduced after treatment respectively (p = 0.021) and (p = 0.002), but between the two groups, no significant difference was observed (p = 0.72). In the experimental (p = 0.005) and control groups (p = 0.001), the intensity of lesions significantly reduced after treatment and there was a significant difference between the two groups (p = 0.001). The mean amount of improvement in pain was significantly greater in the control group compared with the experimental group (p < 0.001) (α = 0.05). Our study showed that TB-PDT with laser was effective in the management of OLP.

  17. Saliva parameters and erosive wear in adolescents

    NARCIS (Netherlands)

    Zwier, N.; Huysmans, M.C.D.N.J.M.; Jager, D.H.J.; Ruben, J.; Bronkhorst, E.M.; Truin, G.J.

    2013-01-01

    The aim of this study was to investigate the relationship between several parameters of saliva and erosive wear in adolescents. (Un-)stimulated saliva was collected from 88 adolescents with erosion and 49 controls (age 16 ± 1 years). Flow rate, pH and buffer capacity were determined immediately.

  18. Saliva Parameters and Erosive Wear in Adolescents

    NARCIS (Netherlands)

    Zwier, N.; Huysmans, M. C. D. N. J. M.; Jager, D. H. J.; Ruben, J.; Bronkhorst, E. M.; Truin, G. J.

    2013-01-01

    The aim of this study was to investigate the relationship between several parameters of saliva and erosive wear in adolescents. (Un-)stimulated saliva was collected from 88 adolescents with erosion and 49 controls (age 16 +/- 1 years). Flow rate, pH and buffer capacity were determined immediately.

  19. Effectiveness of the GAEC standard of cross compliance Prohibition of performing unauthorized land levelling on soil erosion control

    Directory of Open Access Journals (Sweden)

    Paolo Bazzoffi

    2011-08-01

    Full Text Available The GAEC standard land levelling under authorization of cross compliance prohibits farmers from levelling land through bulldozing without a specific permission issued by the proper territorial authority. The aim of the standard is to ensure the protection of soil from accelerated erosion that almost always occurs when land is levelled without conservative criteria. Land levelling prior to planting or replanting specialized crops, especially orchards, is indicated by agronomists as essential to the full mechanization of cultivation and harvesting operations and the success of economic investment. Land levelling leads to a deep modification of the hill slopes, so it may produce serious damage to the environment if carried out in the absence of a carefully planned design. In other words, a design that takes the aspects of soil conservation into account, especially for steep hill slopes where the insite and offsite environmental impacts of soil erosion may be more pronounced. With regard to the areas involved, land levelling plays a key role on a national scale, one only needs to think of the vineyards planted on the country’s hill slopes, which in 1970 covered an area of 793,000 hectares. Moreover, despite the continued reduction in areas planted with vines, from 1990 to 2002 the area devoted to DOC and DOCG wines increased by about 29% and the average size of vineyards has also increased. This is a clear sign of the current trend, with the transition from the family model to the industrial model of orchard management, with extensive use of machinery and thus the use of bulldozers for levelling. The authorization topic, on which the standard of compliance is based, is analysed in detail. In summary we can say that, according to law, the permit required by the GAEC standard is currently mandatory only for those areas subject to the Hydrogeological constraint (Royal decree 30 December 1923 No. 3267 and for parks or other areas for which the

  20. A field demonstration of a modified wet scrubber for dust control in an Illinois coal mine

    Energy Technology Data Exchange (ETDEWEB)

    Chugh, Y.P.; Alam, M.M.; Patwardhan, A.; Thatavarthy, K.K. [Southern Illinois University, Carbondale, IL (United States). Department of Mining and Mineral Resources Engineering

    2005-07-01

    A commercial wet scrubber was used in the SIU-Joy dust control laboratory to test several concepts for improving the dust control efficiency of a wet scrubber. The concepts tested included two filter-two-spray systems, hollow and full-cone sprays, horizontal and vertical sprays, different layer filters and addition of surfactant. The optimised scrubber configuration had water-only vertical sprays for pre-wetting coarse dust, and vertical surfactant-laden water sprays for wetting ultrafine particles. This scrubber configuration reduced dust concentrations from 250 mg/m{sup 3} to 1.8 mg/m{sup 3}. Upon successful testing and optimisation of parameters in the laboratory, field demonstration of the concepts was conducted at an Illinois coal mine. The optimised scrubber configuration was tested in the field with good results in terms of improved visibility in the face area and reduced respirable and quartz dust concentrations. Additional modifications in the field involved relocation of the scrubber suction inlets from the bottom to the side and changing the water spray configuration on the miner head. These additional changes were based on a conceptualised spatial dust distribution profile in the face area. The results of these laboratory development and field demonstration studies are presented in this paper. 6 refs., 11 figs., 4 tabs.

  1. Dental erosion, summary.

    Science.gov (United States)

    ten Cate, J M; Imfeld, T

    1996-04-01

    Although reports on dental erosion have always appeared in the dental literature, there is currently a growing interest among researchers and clinicians. Potential risk factors for dental erosion are changed lifestyle and eating patterns, with increased consumption of acidic foods and beverages. Various gastrointestinal and eating disorders expose the dentition to frequent contacts with very acidic gastric content, which may lead to erosion. Whether these factors indeed lead, on a population scale, to a higher prevalence and incidence of erosion is yet to be established. This article summarizes the different aspects of the prevalence, pathology, etiology, assessment, prevention and treatment of dental erosion, and concludes with recommendations for future research.

  2. Multivariable Control Synthesis Program - Control Aspects of the F100 Altitude Demonstration of the Multivariable Control System.

    Science.gov (United States)

    1980-03-01

    control modes can also reduce the sensitivity to parameter variations and sensor inaccuracies. The F100 (see Figure 2.1) engine was selected for the MVCS...FTS + A - SGB - I GTS (2.11) and by a comparable form for Eq.(2.7). The solution is calculated numerically by integration of the matrix Ricatti...latter schedules the power condition. Dominant gain elements are determined by assessing the closed-loop eigenvalue sensitivity of the system to each

  3. Advanced Instrumentation and Control Methods for Small and Medium Reactors with IRIS Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    J. Wesley Hines; Belle R. Upadhyaya; J. Michael Doster; Robert M. Edwards; Kenneth D. Lewis; Paul Turinsky; Jamie Coble

    2011-05-31

    Development and deployment of small-scale nuclear power reactors and their maintenance, monitoring, and control are part of the mission under the Small Modular Reactor (SMR) program. The objectives of this NERI-consortium research project are to investigate, develop, and validate advanced methods for sensing, controlling, monitoring, diagnosis, and prognosis of these reactors, and to demonstrate the methods with application to one of the proposed integral pressurized water reactors (IPWR). For this project, the IPWR design by Westinghouse, the International Reactor Secure and Innovative (IRIS), has been used to demonstrate the techniques developed under this project. The research focuses on three topical areas with the following objectives. Objective 1 - Develop and apply simulation capabilities and sensitivity/uncertainty analysis methods to address sensor deployment analysis and small grid stability issues. Objective 2 - Develop and test an autonomous and fault-tolerant control architecture and apply to the IRIS system and an experimental flow control loop, with extensions to multiple reactor modules, nuclear desalination, and optimal sensor placement strategy. Objective 3 - Develop and test an integrated monitoring, diagnosis, and prognosis system for SMRs using the IRIS as a test platform, and integrate process and equipment monitoring (PEM) and process and equipment prognostics (PEP) toolboxes. The research tasks are focused on meeting the unique needs of reactors that may be deployed to remote locations or to developing countries with limited support infrastructure. These applications will require smaller, robust reactor designs with advanced technologies for sensors, instrumentation, and control. An excellent overview of SMRs is described in an article by Ingersoll (2009). The article refers to these as deliberately small reactors. Most of these have modular characteristics, with multiple units deployed at the same plant site. Additionally, the topics focus

  4. Sand control with ceramic screens in unconsolidated reservoirs demonstrated in the mature Gaiselberg oilfield

    Energy Technology Data Exchange (ETDEWEB)

    Wildhack, Stefanie [ESK Ceramics GmbH und Co. KG, Kempten (Germany); Muessig, Siegfried; Strahammer, Franz; Leitner, Manfred [Rohoel Aufsuchungs-AG (RAG), Vienna (Austria)

    2012-06-15

    The Oil Production in the operation centre Zistersdorf of the Rohoel-Aufsuchungs AG (RAG) looks back on a long history and a great variety of different types of completions. After the first oil-bearing well RAG-002 in 1937 the development of the RAG field started, followed by more exploration successes in the Gaiselberg oil field from 1938 onwards. The production comes primarily from the sandstone reservoirs of the Sarmat; the deeper horizons usually show a good compaction paired with reasonable permeability. The lower layers, however, are more and more unconsolidated. To prevent sand production and to protect the completion equipment metal screens in combination with gravel packs were installed. Gravel Packs, however, generate an additional pressure drop, which can lead in some cases to a production loss of up to 50% from the very beginning. In addition they are prone to abrasion and incur high completion costs. With the completion of the newly developed sand control screen based on ceramic materials, the next step towards sand control in an unconsolidated reservoir was implemented subsequent to the successful protection of well jewellery in wells after massive hydraulic frac operations. In this article the construction, deployment in the well Ga-016 below a sucker rod pump and the analysis of the production performance are all discussed. It will be demonstrated that with this application a fundamental step in sand control in unconsolidated reservoirs has been achieved. (orig.)

  5. Temporal and spatial climatic controls on Holocene fire-related erosion and sedimentation, Jemez Mountains, New Mexico

    Science.gov (United States)

    Fitch, Erin P.; Meyer, Grant A.

    2016-01-01

    In the Jemez Mountains, tree-ring data indicate that low-severity fires characterized the 400 yr before Euro-American settlement, and that subsequent fire suppression promoted denser forests, recent severe fires, and erosion. Over longer timescales, climate change may alter fire regimes; thus, we used fire-related alluvial deposits to assess the timing of moderate- to high-severity fires, their geomorphic impact, and relation to climate over the last 4000 yr. Fire-related sedimentation does not clearly follow millennial-scale climatic changes, but probability peaks commonly correspond with severe drought, e.g., within the interval 1700-1400 cal yr BP, and ca. 650 and ca. 410 cal yr BP. The latter episodes were preceded by prolonged wet intervals that could promote dense stands. Estimated recurrence intervals for fire-related sedimentation are 250-400 yr. Climatic differences with aspect influenced Holocene post-fire response: fire-related deposits constitute 77% of fan sediments from north-facing basins but only 39% of deposits from drier southerly aspects. With sparser vegetation and exposed bedrock, south aspects can generate runoff and sediment when unburned, whereas soil-mantled north aspects produce minor sediment unless severely burned. Recent channel incision appears unprecedented over the last 2300 yr, suggesting that fuel loading and extreme drought produced an anomalously severe burn in 2002.

  6. Effect of a chitosan additive to a Sn2+-containing toothpaste on its anti-erosive/anti-abrasive efficacy--a controlled randomised in situ trial.

    Science.gov (United States)

    Schlueter, N; Klimek, J; Ganss, C

    2014-01-01

    It is well known that Sn(2+) is a notable anti-erosive agent. There are indications that biopolymers such as chitosan can enhance the effect of Sn(2+), at least in vitro. However, little information exists about their anti-erosive/anti-abrasive in situ effects. In the present in situ study, the efficacy of Sn(2+)-containing toothpastes in the presence or absence of chitosan was tested. Ten subjects participated in the randomised crossover study, wearing mandibular appliances with human enamel specimens. Specimens were extraorally demineralised (7 days, 0.5% citric acid, pH 2.6; 6 × 2 min/day) and intraorally exposed to toothpaste suspensions (2 × 2 min/day). Within the suspension immersion time, one half of the specimens were additionally brushed intraorally with a powered toothbrush (5 s, 2.5 N). Tested preparations were a placebo toothpaste (negative control), two experimental toothpastes (F/Sn = 1,400 ppm F(-), 3,500 ppm Sn(2+); F/Sn/chitosan = 1,400 ppm F(-), 3,500 ppm Sn(2+), 0.5 % chitosan) and an SnF2-containing gel (positive control, GelKam = 3,000 ppm Sn(2+), 1,000 ppm F(-)). Substance loss was quantified profilometrically (μm). In the placebo group, tissue loss was 11.2 ± 4.6 (immersion in suspension) and 17.7 ± 4.7 (immersion in suspension + brushing). Immersion in each Sn(2+)-containing suspension significantly reduced tissue loss (p ≤ 0.01); after immersion in suspension + brushing, only the treatments with GelKam (5.4 ± 5.5) and with F/Sn/chitosan (9.6 ± 5.6) significantly reduced loss [both p ≤ 0.05 compared to placebo; F/Sn 12.8 ± 6.4 (not significant)] Chitosan enhanced the efficacy of the Sn(2+)-containing toothpaste as an anti-erosive/anti-abrasive agent. The use of Sn(2+)- and chitosan-containing toothpaste is a good option for symptomatic therapy in patients with regular acid impacts.

  7. Innovative Adaptive Control Method Demonstrated for Active Suppression of Instabilities in Engine Combustors

    Science.gov (United States)

    Kopasakis, George

    2005-01-01

    This year, an improved adaptive-feedback control method was demonstrated that suppresses thermoacoustic instabilities in a liquid-fueled combustor of a type used in aircraft engines. Extensive research has been done to develop lean-burning (low fuel-to-air ratio) combustors that can reduce emissions throughout the mission cycle to reduce the environmental impact of aerospace propulsion systems. However, these lean-burning combustors are susceptible to thermoacoustic instabilities (high-frequency pressure waves), which can fatigue combustor components and even downstream turbine blades. This can significantly decrease the safe operating life of the combustor and turbine. Thus, suppressing the thermoacoustic combustor instabilities is an enabling technology for meeting the low-emission goals of the NASA Ultra-Efficient Engine Technology (UEET) Project.

  8. Estimation of the rational water area for controlling wind erosion in the dried-up basin of the Ebinur Lake and its effect detection

    Institute of Scientific and Technical Information of China (English)

    BAO Anming; MU Guijin; ZHANG Yi; FENG Xianwei; CHANG Gun; YIN Xiaojun

    2006-01-01

    The Ebinur Lake region was described as a "Green Labyrinth" in "Xinjiang Map Records:Records of Rivers" published in 1910, however, the ecology and environment in the region have been seriously degenerated due to the impacts of human activities during the recent 40 years. A dried-up lake basin with an area of 107.4 km2 forms in its northwestern part, is covered by unconsolidated silt deposit without vegetation, and has become one of the main dust sources of dust weathers in north Xinjiang,and the dust with an annual amount of 4.8×106 t is blown out of the region by strong winds from the Alataw mountain-gap where there are 164 days occurring strong winds in a year. The rational water area and inflow of the Ebinur Lake for improving the ecology in the lake region and effectively controlling wind erosion in the dried-up lake basin are estimated using the water balance equation after analyzing the current ecological problems and the relationship between the granular composition of deposit in the dried-up lake basin and the dust weathers, and the ecological effects in recent years are monitored. It is considered that the water area of the Ebinur Lake for improving the ecology in the lake region and effectively controlling wind erosion in the dried-up lake basin should be 800 km2 at least, and the annual volume of surface runoff and groundwater recharging the lake should be over 7.92×108 m3.

  9. Modelling rainfall erosion resulting from climate change

    Science.gov (United States)

    Kinnell, Peter

    2016-04-01

    It is well known that soil erosion leads to agricultural productivity decline and contributes to water quality decline. The current widely used models for determining soil erosion for management purposes in agriculture focus on long term (~20 years) average annual soil loss and are not well suited to determining variations that occur over short timespans and as a result of climate change. Soil loss resulting from rainfall erosion is directly dependent on the product of runoff and sediment concentration both of which are likely to be influenced by climate change. This presentation demonstrates the capacity of models like the USLE, USLE-M and WEPP to predict variations in runoff and erosion associated with rainfall events eroding bare fallow plots in the USA with a view to modelling rainfall erosion in areas subject to climate change.

  10. Active vibration control testing of the SPICES program: final demonstration article

    Science.gov (United States)

    Dunne, James P.; Jacobs, Jack H.

    1996-05-01

    The Synthesis and Processing of Intelligent Cost Effective Structures (SPICES) Program is a partnership program sponsored by the Advanced Research Projects Agency. The mission of the program is to develop cost effective material processing and synthesis technologies to enable new products employing active vibration suppression and control devices to be brought to market. The two year program came to fruition in 1995 through the fabrication of the final smart components and testing of an active plate combined with two trapezoidal rails, forming an active mount. Testing of the SPICES combined active mount took place at McDonnell Douglas facilities in St. Louis, MO, in October-December 1995. Approximately 15 dB reduction in overall response of a motor mounted on the active structure was achieved. Further details and results of the SPICES combined active mount demonstration testing are outlined. Results of numerous damping and control strategies that were developed and employed in the testing are presented, as well as aspects of the design and fabrication of the SPICES active mount components.

  11. AZ-101 Mixer Pump Demonstration Data Acquisition System and Gamma Cart Data Acquisition Control System Software Configuration Management Plan

    Energy Technology Data Exchange (ETDEWEB)

    WHITE, D.A.

    1999-12-29

    This Software Configuration Management Plan (SCMP) provides the instructions for change control of the AZ1101 Mixer Pump Demonstration Data Acquisition System (DAS) and the Sludge Mobilization Cart (Gamma Cart) Data Acquisition and Control System (DACS).

  12. 紫色土坡耕地细沟侵蚀的防治%Prevention and control of rill erosion on purple soil slope cultivated land

    Institute of Scientific and Technical Information of China (English)

    唐成毅; 严冬春; 龚长文; 向茂青

    2012-01-01

    坡耕地是紫色土区域典型的土地利用方式,细沟侵蚀是紫色土坡面侵蚀的主要形式之一.试验研究发现,10°,15°,20°,25°小区细沟侵蚀量占坡面总侵蚀量的比例分别为28.61%,57.66%,80.66%和91.16%;细沟沟头出现的顺坡临界坡长平均值分别为6.19m,4.15m,2.75m,1.57m.在大量野外调查的基础上,采用植物篱、“地埂十植物篱”和“大横坡十小顺坡”3种措施均能控制细沟侵蚀的发生.尤其是“大横坡十小顺坡”模式,兼具了植物篱与“地埂十植物篱”两种措施的优点,且造价低、节省劳力,具有较好的推广前景,特别是暂时无法实施坡改梯的广大偏远山区.%Rill erosion is one of the main erosion types on the purple soil slope cultivated land. It accounts for 28. 61%, 57. 66%, 80. 66% and 91. 16% when the slope gradients are 10°,15°,20°and 25°, respectively. Thereby, it is necessary to prevent rill initiation using appropriate measures in the interest of conserving soils. In the Five Years Development Project of Eleventh, some prevention and control measures were investigated by the research group of the slope cultivated land management in the Yangtze River area. In sum, the measures included hedgerows, "ridge + hedgerows" and "downslope ridge tillage and cross trenches". Among them, the key technology is to change the runoff flow direction on the critical length of rill initiation so as to prevent the rill erosion. The preliminary effect investigation shows some excellences in the environment and economy. The preferable estimation shows that these measures have advantages of operation and save inputs including investment and labor. Therefore, it is worth extending implemental areas, especially in the underdeveloped mountain regions.

  13. 'Natural experiment' demonstrates top-down control of spiders by birds on a landscape level.

    Directory of Open Access Journals (Sweden)

    Haldre Rogers

    Full Text Available The combination of small-scale manipulative experiments and large-scale natural experiments provides a powerful approach for demonstrating the importance of top-down trophic control on the ecosystem scale. The most compelling natural experiments have come from studies examining the landscape-scale loss of apex predators like sea otters, wolves, fish and land crabs. Birds are dominant apex predators in terrestrial systems around the world, yet all studies on their role as predators have come from small-scale experiments; the top-down impact of bird loss on their arthropod prey has yet to be examined at a landscape scale. Here, we use a unique natural experiment, the extirpation of insectivorous birds from nearly all forests on the island of Guam by the invasive brown tree snake, to produce the first assessment of the impacts of bird loss on their prey. We focused on spiders because experimental studies showed a consistent top-down effect of birds on spiders. We conducted spider web surveys in native forest on Guam and three nearby islands with healthy bird populations. Spider web densities on the island of Guam were 40 times greater than densities on islands with birds during the wet season, and 2.3 times greater during the dry season. These results confirm the general trend from manipulative experiments conducted in other systems however, the effect size was much greater in this natural experiment than in most manipulative experiments. In addition, bird loss appears to have removed the seasonality of spider webs and led to larger webs in at least one spider species in the forests of Guam than on nearby islands with birds. We discuss several possible mechanisms for the observed changes. Overall, our results suggest that effect sizes from smaller-scale experimental studies may significantly underestimate the impact of bird loss on spider density as demonstrated by this large-scale natural experiment.

  14. Advanced Instrumentation and Control Methods for Small and Medium Reactors with IRIS Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    J. Wesley Hines; Belle R. Upadhyaya; J. Michael Doster; Robert M. Edwards; Kenneth D. Lewis; Paul Turinsky; Jamie Coble

    2011-05-31

    Development and deployment of small-scale nuclear power reactors and their maintenance, monitoring, and control are part of the mission under the Small Modular Reactor (SMR) program. The objectives of this NERI-consortium research project are to investigate, develop, and validate advanced methods for sensing, controlling, monitoring, diagnosis, and prognosis of these reactors, and to demonstrate the methods with application to one of the proposed integral pressurized water reactors (IPWR). For this project, the IPWR design by Westinghouse, the International Reactor Secure and Innovative (IRIS), has been used to demonstrate the techniques developed under this project. The research focuses on three topical areas with the following objectives. Objective 1 - Develop and apply simulation capabilities and sensitivity/uncertainty analysis methods to address sensor deployment analysis and small grid stability issues. Objective 2 - Develop and test an autonomous and fault-tolerant control architecture and apply to the IRIS system and an experimental flow control loop, with extensions to multiple reactor modules, nuclear desalination, and optimal sensor placement strategy. Objective 3 - Develop and test an integrated monitoring, diagnosis, and prognosis system for SMRs using the IRIS as a test platform, and integrate process and equipment monitoring (PEM) and process and equipment prognostics (PEP) toolboxes. The research tasks are focused on meeting the unique needs of reactors that may be deployed to remote locations or to developing countries with limited support infrastructure. These applications will require smaller, robust reactor designs with advanced technologies for sensors, instrumentation, and control. An excellent overview of SMRs is described in an article by Ingersoll (2009). The article refers to these as deliberately small reactors. Most of these have modular characteristics, with multiple units deployed at the same plant site. Additionally, the topics focus

  15. Control Demonstration of Multiple Doubly-Fed Induction Motors for Hybrid Electric Propulsion

    Science.gov (United States)

    Sadey, David J.; Bodson, Marc; Csank, Jeffrey T.; Hunker, Keith R.; Theman, Casey J.; Taylor, Linda M.

    2017-01-01

    The Convergent Aeronautics Solutions (CAS) High Voltage-Hybrid Electric Propulsion (HVHEP) task was formulated to support the move into future hybrid-electric aircraft. The goal of this project is to develop a new AC power architecture to support the needs of higher efficiency and lower emissions. This proposed architecture will adopt the use of the doubly-fed induction machine (DFIM) for propulsor drive motor application.The Convergent Aeronautics Solutions (CAS) High Voltage-Hybrid Electric Propulsion (HVHEP) task was formulated to support the move into future hybrid-electric aircraft. The goal of this project is to develop a new AC power architecture to support the needs of higher efficiency and lower emissions. This proposed architecture will adopt the use of the doubly-fed induction machine (DFIM) for propulsor drive motor application. DFIMs are attractive for several reasons, including but not limited to the ability to self-start, ability to operate sub- and super-synchronously, and requiring only fractionally rated power converters on a per-unit basis depending on the required range of operation. The focus of this paper is based specifically on the presentation and analysis of a novel strategy which allows for independent operation of each of the aforementioned doubly-fed induction motors. This strategy includes synchronization, soft-start, and closed loop speed control of each motor as a means of controlling output thrust; be it concurrently or differentially. The demonstration of this strategy has recently been proven out on a low power test bed using fractional horsepower machines. Simulation and hardware test results are presented in the paper.

  16. Demonstration of UAV deployment and control of mobile wireless sensing networks for modal analysis of structures

    Science.gov (United States)

    Zhou, Hao; Hirose, Mitsuhito; Greenwood, William; Xiao, Yong; Lynch, Jerome; Zekkos, Dimitrios; Kamat, Vineet

    2016-04-01

    Unmanned aerial vehicles (UAVs) can serve as a powerful mobile sensing platform for assessing the health of civil infrastructure systems. To date, the majority of their uses have been dedicated to vision and laser-based spatial imaging using on-board cameras and LiDAR units, respectively. Comparatively less work has focused on integration of other sensing modalities relevant to structural monitoring applications. The overarching goal of this study is to explore the ability for UAVs to deploy a network of wireless sensors on structures for controlled vibration testing. The study develops a UAV platform with an integrated robotic gripper that can be used to install wireless sensors in structures, drop a heavy weight for the introduction of impact loads, and to uninstall wireless sensors for reinstallation elsewhere. A pose estimation algorithm is embedded in the UAV to estimate the location of the UAV during sensor placement and impact load introduction. The Martlet wireless sensor network architecture is integrated with the UAV to provide the UAV a mobile sensing capability. The UAV is programmed to command field deployed Martlets, aggregate and temporarily store data from the wireless sensor network, and to communicate data to a fixed base station on site. This study demonstrates the integrated UAV system using a simply supported beam in the lab with Martlet wireless sensors placed by the UAV and impact load testing performed. The study verifies the feasibility of the integrated UAV-wireless monitoring system architecture with accurate modal characteristics of the beam estimated by modal analysis.

  17. Taxation of Controlled Foreign Companies in Context of the OECD/G20 Project on Base Erosion and Profit Shifting as well as the EU Proposal for the Anti-Tax Avoidance Directive

    DEFF Research Database (Denmark)

    Schmidt, Peter Koerver

    2016-01-01

    Recently, the controlled foreign company (CFC) rules have gained increased attention; as such, rules play an important role in the ongoing efforts of the OECD/G20 and the European Commission with respect to addressing base erosion and profit shifting (BEPS). In this context, the article revisits...

  18. Taxation of Controlled Foreign Companies in Context of the OECD/G20 Project on Base Erosion and Profit Shifting as well as the EU Proposal for the Anti-Tax Avoidance Directive

    DEFF Research Database (Denmark)

    Schmidt, Peter Koerver

    2016-01-01

    Recently, the controlled foreign company (CFC) rules have gained increased attention; as such, rules play an important role in the ongoing efforts of the OECD/G20 and the European Commission with respect to addressing base erosion and profit shifting (BEPS). In this context, the article revisits...

  19. Climate control on silicate weathering and physical erosion rates in young orogenic belts: Case study along a runoff gradient in Pacific and Amazonian Andean basins based on SNO-HYBAM Monitoring Program data

    Science.gov (United States)

    Moquet, Jean-Sébastien; Guyot, Jean-Loup; Viers, Jérôme; Crave, Alain; Morera, Sergio; Rau, Pedro; Armijos, Elisa; Lagane, Christelle; Sven Lavado Casimiro, Waldo; Pombosa, Rodrigo; Fraizy, Pascal; Santini, William; Timouk, Franck; Vauchel, Philippe; Martinez, Jean-Michel

    2017-04-01

    At the global scale and on geological time scales, mechanical erosion and chemical weathering budgets are linked. Together, these processes contribute to the formation and the degradation of the Earth's critical zone and to the biogeochemical cycles of elements. In young orogenic belts, climate and tectonic subsidence control together the rate of these matter balance budget and their relationships. The climate gradient observed along the Andean basin in both the Pacific and the Atlantic slopes offers the opportunity to explore the role of the climate variability on the erosion and weathering budgets and on their reciprocal relationships. Based on the SNO-HYBAM Monitoring Program database (Geodynamical, hydrological and Biogeochemical control of erosion/weathering and material transport in the Amazon, Orinoco and Congo basins), we explore the relationship between climate, the lithology, silicate weathering rates and physical erosion rates along a runoff gradient in Andean basins of the Amazon River (13 gauging stations) and Pacific drainage rivers (5 gauging stations). No homogenous relationship between erosion rates (E) and chemical weathering rate (W) is observed over the monitored basins. Only the volcanic basins respond to a global relationship defined in the literature while the other basins budget may depend on anthropogenic interferences on erosion/sedimentation budget, a lithology dependence of the W-E relationship parameters or/and on the existence of a threshold in this relationship. The results presented here contribute to better understanding the role of mountains belt formation in the biogeochemical cycles and in particular in the long-term carbon cycle.Your presentation type preference.

  20. Erosion Negril Beach

    NARCIS (Netherlands)

    Ten Ham, D.; Henrotte, J.; Kraaijeveld, R.; Milosevic, M.; Smit, P.

    2006-01-01

    The ongoing erosion of the Negril Beach has become worse the past decade. In most places along the coast line, the beach will be gone in approximately 10 years. This will result in a major decrease of incomes that are made by the local tourist sector. To prevent the erosion this study has been perfo

  1. Saliva and dental erosion

    Science.gov (United States)

    BUZALAF, Marília Afonso Rabelo; HANNAS, Angélicas Reis; KATO, Melissa Thiemi

    2012-01-01

    Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. Objective This review discusses the role of salivary factors on the development of dental erosion. Material and Methods A search was undertaken on MEDLINE website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Results Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Conclusions Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects. PMID:23138733

  2. Saliva and dental erosion

    Directory of Open Access Journals (Sweden)

    Marília Afonso Rabelo Buzalaf

    2012-10-01

    Full Text Available Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. Objective: This review discusses the role of salivary factors on the development of dental erosion. Material and Methods: A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Results: Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Conclusions: Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

  3. Testbed Demonstration of Low Order Wavefront Sensing and Control Technology for WFIRST Coronagraph

    Science.gov (United States)

    Shi, Fang; Balasubramanian, K.; Cady, E.; Kern, B.; Lam, R.; Mandic, M.; Patterson, K.; Poberezhskiy, I.; Shields, J.; Seo, J.; Tang, H.; Truong, T.; Wilson, D.

    2017-01-01

    NASA’s WFIRST-AFTA Coronagraph will be capable of directly imaging and spectrally characterizing giant exoplanets similar to Neptune and Jupiter, and possibly even super-Earths, around nearby stars. To maintain the required coronagraph performance in a realistic space environment, a Low Order Wavefront Sensing and Control (LOWFS/C) subsystem is necessary. The LOWFS/C will use the rejected stellar light to sense and suppress the telescope pointing drift and jitter as well as low order wavefront errors due to the changes in thermal loading of the telescope and the rest of the observatory. The LOWFS/C uses a Zernike phase contrast wavefront sensor with the phase shifting disk combined with the stellar light rejecting occulting mask, a key concept to minimize the non-common path error. Developed as a part of the Dynamic High Contrast Imaging Testbed (DHCIT), the LOWFS/C subsystem also consists of an Optical Telescope Assembly Simulator (OTA-S) to generate the realistic line-of-sight (LoS) drift and jitter as well as low order wavefront error from WFIRST-AFTA telescope’s vibration and thermal drift. The entire LOWFS/C subsystem have been integrated, calibrated, and tested in the Dynamic High Contrast Imaging Testbed. In this presentation we will show the results of LOWFS/C performance during the dynamic coronagraph tests in which we have demonstrated that LOWFS/C is able to maintain the coronagraph contrast with the presence of WFIRST like line-of-sight drift and jitter as well as low order wavefront drifts.

  4. Guidance and Control Architecture Design and Demonstration for Low Ballistic Coefficient Atmospheric Entry

    Science.gov (United States)

    Swei, Sean

    2014-01-01

    We propose to develop a robust guidance and control system for the ADEPT (Adaptable Deployable Entry and Placement Technology) entry vehicle. A control-centric model of ADEPT will be developed to quantify the performance of candidate guidance and control architectures for both aerocapture and precision landing missions. The evaluation will be based on recent breakthroughs in constrained controllability/reachability analysis of control systems and constrained-based energy-minimum trajectory optimization for guidance development operating in complex environments.

  5. Magnetic field penetration of erosion switch plasmas

    Science.gov (United States)

    Mason, Rodney J.; Jones, Michael E.; Grossmann, John M.; Ottinger, Paul F.

    1988-10-01

    Computer simulations demonstrate that the entrainment (or advection) of magnetic field with the flow of cathode-emitted electrons can constitute a dominant mechanism for the magnetic field penetration of erosion switch plasmas. Cross-field drift in the accelerating electric field near the cathode starts the penetration process. Plasma erosion propagates the point for emission and magnetic field injection along the cathode toward the load-for the possibility of rapid switch opening.

  6. Experimental demonstration of a classical approach for flexible space structure control: NASA CSI testbeds

    Science.gov (United States)

    Bond, Wie

    1991-01-01

    The results of active control experiments performed for the Mini-Mast truss structure are presented. The primary research objectives were: (1) to develop active structural control concepts and/or techniques; (2) to verify the concept of robust non-minimum-phase compensation for a certain class of non-colocated structural control problems through ground experiments; (3) to verify a 'dipole' concept for persistent disturbance rejection control of flexible structures; and (4) to identify CSI (Control Structure Interaction) issues and areas of emphasis for the next generation of large flexible spacecraft. The classical SISO (Single Input and Single Output) control design approach was employed.

  7. Erosion resistance of bionic functional surfaces inspired from desert scorpions.

    Science.gov (United States)

    Zhiwu, Han; Junqiu, Zhang; Chao, Ge; Li, Wen; Ren, Luquan

    2012-02-01

    In this paper, a bionic method is presented to improve the erosion resistance of machine components. Desert scorpion (Androctonus australis) is a typical animal living in sandy deserts, and may face erosive action of blowing sand at a high speed. Based on the idea of bionics and biologic experimental techniques, the mechanisms of the sand erosion resistance of desert scorpion were investigated. Results showed that the desert scorpions used special microtextures such as bumps and grooves to construct the functional surfaces to achieve the erosion resistance. In order to understand the erosion resistance mechanisms of such functional surfaces, the combination of computational and experimental research were carried out in this paper. The Computational Fluid Dynamics (CFD) method was applied to predict the erosion performance of the bionic functional surfaces. The result demonstrated that the microtextured surfaces exhibited better erosion resistance than the smooth surfaces. The further erosion tests indicated that the groove surfaces exhibited better erosion performance at 30° injection angle. In order to determine the effect of the groove dimensions on the erosion resistance, regression analysis of orthogonal multinomials was also performed under a certain erosion condition, and the regression equation between the erosion rate and groove distance, width, and height was established.

  8. Demonstration of An Integrated Approach to Mercury Control at Lee Station

    Energy Technology Data Exchange (ETDEWEB)

    Vitali Lissianski; Pete Maly

    2007-12-31

    General Electric (GE) has developed an approach whereby native mercury reduction on fly ash can be improved by optimizing the combustion system. This approach eliminates carbon-rich areas in the combustion zone, making the combustion process more uniform, and allows increasing carbon content in fly ash without significant increase in CO emissions. Since boiler excess O{sub 2} can be also reduced as a result of optimized combustion, this process reduces NO{sub x} emissions. Because combustion optimization improves native mercury reduction on fly ash, it can reduce requirements for activated carbon injection (ACI) when integrated with sorbent injection for more efficient mercury control. The approach can be tailored to specific unit configurations and coal types for optimal performance. This report describes results of a U.S. DOE sponsored project designed to evaluate the effect of combustion conditions on 'native' mercury capture on fly ash and integrate combustion optimization for improved mercury and NO{sub x} reduction with ACI. The technology evaluation took place in Lee Station Unit 3 located in Goldsboro, NC and operated by Progress Energy. Unit 3 burns a low-sulfur Eastern bituminous coal and is a 250 MW opposed-wall fired unit equipped with an ESP with a specific collection area of 249 ft{sup 2}/kacfm. Unit 3 is equipped with SO{sub 3} injection for ESP conditioning. The technical goal of the project was to evaluate the technology's ability to achieve 70% mercury reduction below the baseline emission value of 2.9 lb/TBtu, which was equivalent to 80% mercury reduction relative to the mercury concentration in the coal. The strategy to achieve the 70% incremental improvement in mercury removal in Unit 3 was (1) to enhance 'naturally' occurring fly ash mercury capture by optimizing the combustion process and using duct humidification to reduce flue gas temperatures at the ESP inlet, and (2) to use ACI in front of the ESP to further

  9. Demonstration of Single Axis Combined Attitude Control and Energy Storage Using Two Flywheels

    Science.gov (United States)

    Kenny, Barbara H.; Jansen, Ralph; Kascak, Peter; Dever, Timothy; Santiago, Walter

    2004-01-01

    The energy storage and attitude control subsystems of the typical satellite are presently distinct and separate. Energy storage is conventionally provided by batteries, either NiCd or NiH, and active attitude control is accomplished with control moment gyros (CMGs) or reaction wheels. An overall system mass savings can be realized if these two subsystems are combined using multiple flywheels for simultaneous kinetic energy storage and momentum transfer. Several authors have studied the control of the flywheels to accomplish this and have published simulation results showing the feasibility and performance. This paper presents the first experimental results showing combined energy storage and momentum control about a single axis using two flywheels.

  10. The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Appendix A. Literature Survey.

    Science.gov (United States)

    1981-12-01

    Dyer, C. E., "Revetment--Stabilization of the Channel of the Rio Grande from Caballo Dam to Fort Quitman, New Mexico-Texas," Symposium on Channel...Stabilization of the Channel of the Rio Grande from Caballo Dam to Fort Quitman, New Mexico-Texas," Symposium on Channel Stabilization Problems, Technical

  11. The Streambank Erosion Control Evaluation and Demonstration Act of 1974, Section 32, Public Law 93-251. Appendix C. Geotechnical Research.

    Science.gov (United States)

    1981-12-01

    along the banks, secondary currents, freeze-thaw, and bed aggradation as eroded soil from upstream is deposited at the reach of the river under...reinforced headbox , fitted with a motorized aluminum headgate and turning vanes to direct the flow of the water (Figure C29), is mounted on the...does not take into account variations in tractive shear stress due to spiral (or helicoidal) flow, secondary currents, or flow separation in curved

  12. [Experiences of comprehensive control of parasitic diseases in demonstration plot of Xiangyun County, Yunnan Province].

    Science.gov (United States)

    Li-Bo, Wang; Yan-Hong, Li; Wen-Juan, Li; Du, Zun-Wei; Jiang, Jin-Yong

    2011-10-01

    We established and perfected the system of control work, achieved the expected targets, and explored the advisable pattern for prevention and control on soil-transmitted nematode diseases. To perform the prevention and control on soil-transmitted nematodiasis, there should be the guidance of government, the multi-sectoral cooperation, community participation, paying attention to the organization and management, and highlighting the key points including education and deworming.

  13. Environmental Impact of Introducing Aromatic-Shrub Strips in Almond Orchards under Semiarid Climate (SE Spain): implications for Erosion and Agricultural Runoff Control

    Energy Technology Data Exchange (ETDEWEB)

    Duran-Zuazo, V. H.; Rodriguez-Pleguezuelo, C. R.; Francia-Martinez, J. R.; Martinez-Raya, A.; Carceles-Rodriguez, B.; Arroyo-Panadero, L.; Casado, J. P.

    2009-07-01

    Erosion degrades soil quality in natural, agricultural, and forest ecosystems, thereby reducing the productivity of the land. Semi-natural vegetation and diverse cropping systems have been converted into monocultures with low tree densities, leaving the soil unprotected. Soil loss, runoff, and nutrient loss over a four-year period were monitored in hillside erosion plots with almond trees under different soil-management systems. (Author)

  14. Sets resilient to erosion

    CERN Document Server

    Pegden, Wesley

    2011-01-01

    The erosion of a set in Euclidean space by a radius r>0 is the subset of X consisting of points at distance >/-r from the complement of X. A set is resilient to erosion if it is similar to its erosion by some positive radius. We give a somewhat surprising characterization of resilient sets, consisting in one part of simple geometric constraints on convex resilient sets, and, in another, a correspondence between nonconvex resilient sets and scale-invariant (e.g., 'exact fractal') sets.

  15. Potential impacts of climate change on soil erosion vulnerability across the conterminous United States

    Science.gov (United States)

    C. Segura; G. Sun; S. McNulty; Y. Zhang

    2014-01-01

    Rainfall runoff erosivity (R) is one key climate factor that controls water erosion. Quantifying the effects of climate change-induced erosivity change is important for identifying critical regions prone to soil erosion under a changing environment. In this study we first evaluate the changes of R from 1970 to 2090 across the United States under nine climate conditions...

  16. Power source equipment for Hokuriku Chiken`s Matsumoto office for erosion control work; Hokuriku chiken Matsumoto sabo koji jimusho muke dengen setsubi

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-10

    As part of Meidensha`s deliveries to the government offices, a power source equipment was supplied to Hokuriku Chiken`s Matsumoto office for erosion control work. It is a set of high tension power receiving/transforming equipment and private electric generator for Yakedake supervisor`s station. This system is for supplying electricity to the wireless communication system of the three relay stations. In view of the long distance feed to the stations, the 210V power supply for the government office building is transmitted after boosting to 6.6KV or 420V by a step-up transformer. System interconnection with a small hydraulic power generator is being planned for the future, while a photovoltaic generation set is already on order for the government office building, and, as such, energy conservation is dealt with positively by the government. The outline of the delivered equipment is as follows. The 6.6KV high tension power receiving/transforming equipment is provided with one unit of 12 plane high/low-tension board, three-phase mold transformer 100KVA; the private electric generator is equipped with one unit of three-phase 210V, 75KVA Diesel-engine generator. (NEDO)

  17. MODELING EPHEMERAL GULLY EROSION FOR CONSERVATION PLANNING

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This paper discusses the overland flow and concentrated flow systems that occur in most farm fields. Concentrated flow areas, which are distinct from overland flow areas, can be a major sediment source and are the main conduits that convey runoff and sediment from most farm fields. Ephemeral gully erosion, which occurs in concentrated flow areas, is similar to but differs from both rill and classical gully erosion. Concentrated flow areas occupy much of the flow path between the end of overland flow areas and defined stream channels. This paper describes the erosion and deposition processes that occur in concentrated flow areas and the effect of soil and cover management on these processes. Ephemeral gully erosion is not estimated with rill-interrill erosion prediction methods, which can result in major errors in estimates of sediment yield leaving farm fields. Much deposition can occur in concentrated flow areas resulting in sediment load leaving a farm field being much less than the sediment produced by rill-interrill and ephemeral gully erosion within the field. This paper describes model structure, topographic representation, and features of ephemeral gully erosion control practices needed in mathematical models used in conservation planning for farm fields.

  18. Influence of fruit consumption and fluoride application on the prevalence of caries and erosion in vegetarians--a controlled clinical trial.

    Science.gov (United States)

    Staufenbiel, I; Adam, K; Deac, A; Geurtsen, W; Günay, H

    2015-10-01

    Caries and erosion are common diseases of the dental hard tissues. The influence of vegetarianism on the development of caries and erosion has scarcely been investigated in the past. The aim of the present study was to evaluate the influence of fruit consumption and topical fluoride application on the prevalence of caries and erosion in vegetarians. In 100 vegetarians and 100 nonvegetarians, a dental examination was performed. The indices for decayed, missing, filled teeth (DMFT) and surfaces (DMFS) were determined. DMFT and DMFS were subdivided into decayed teeth (DT), filled teeth (FT), decayed surfaces (DS) and filled surfaces (FS). In addition, the hygiene index and the number of teeth with dental erosion (DE), root caries (RC) and overhanging restoration margins (ORM) were recorded. A questionnaire assessed patients' eating habits, frequency of oral hygiene, dentist visits and topical fluoride application. For statistical analysis, unpaired t-test, Mann-Whitney test and Pearson's chi-square test were applied. Vegetarians had significantly more DT (Pvegetarians compared with nonvegetarians. In particular, fluoride-containing toothpaste (Pvegetarians. The presented data suggest that vegetarians have an increased risk for caries and erosion. Topical fluoride application was shown to be effective in preventing caries, but not in preventing erosion.

  19. Demonstration of visualization techniques for the control room engineer in 2030

    DEFF Research Database (Denmark)

    Marinelli, Mattia; Heussen, Kai; Strasser, Thomas

    2017-01-01

    Deliverable 8.1 reports results on analytics and visualizations of real time flexibility in support of voltage and frequency control in 2030+ power system. The investigation is carried out by means of relevant control room scenarios in order to derive the appropriate analytics needed for each...

  20. Metabolic syndrome is associated with erosive esophagitis

    Institute of Scientific and Technical Information of China (English)

    Jung Ho Park; Dong IL Park; Hong Joo Kim; Yong Kyun Cho; Chong IL Sohn; Woo Kyu Jeon; Byung Ik Kim

    2008-01-01

    AIM: To clarify whether insulin resistance and metabolic syndrome are risk factors for erosive esophagitis.METHODS: A case-control study was performed using the database of the Kangbuk Semsung Hospital Medical Screening Center.RESULTS: A total of 1679 cases of erosive esophagitis and 3358 randomly selected controls were included.Metabolic syndrome was diagnosed in 21% of the cases and 12% of the controls (P<0.001).Multiple logistic regressions confirmed the association between erosive esophagitis and metabolic syndrome (Odds ratio,1.25; 95% CI,1.04-1.49).Among the components of metabolic syndrome,increased waist circumference,elevated serum triglyceride levels and hypertension were significant risk factors for erosive esophagitis (allP<0.01).Furthermore,increased insulin resistance (Odds ratio,0.91; 95% CI,0.85-0.98)and fatty liver,as diagnosed by ultrasonography (odds ratio,1.39; 95% CI,1.20-1.60),were also related to erosive esophagitis even after adjustment for a series of confounding factors.CONCLUSION: Metabolic syndrome and increased insulin resistance are associated with an increased risk of developing erosive esophagitis.

  1. Enzymatic surface erosion of high tensile strength polycarbonates based on natural phenols.

    Science.gov (United States)

    Sommerfeld, Sven D; Zhang, Zheng; Costache, Marius C; Vega, Sebastián L; Kohn, Joachim

    2014-03-10

    Surface erosion has been recognized as a valuable design tool for resorbable biomaterials within the context of drug delivery devices, surface coatings, and when precise control of strength retention is critical. Here we report on high tensile strength, aromatic-aliphatic polycarbonates based on natural phenols, tyrosol (Ty) and homovanillyl alcohol (Hva), that exhibit enzymatic surface erosion by lipase. The Young's moduli of the polymers for dry and fully hydrated samples are 1.0 to 1.2 GPa and 0.8 to 1.2 GPa, respectively. Typical characteristics of enzymatic surface erosion were confirmed for poly(tyrosol carbonate) films with concomitant mass-loss and thickness-loss at linear rates of 0.14 ± 0.01 mg cm(-2) d(-1) and 3.0 ± 0.8 μm d(-1), respectively. The molecular weight and the mechanical properties of the residual films remained constant. Changing the ratio of Ty and Hva provided control over the glass transition temperature (T(g)) and the enzymatic surface erosion: increasing the Hva content in the polymers resulted in higher T(g) and lower enzymatic erosion rate. Polymers with more than 50 mol % Hva were stable at 37 °C in enzyme solution. Analysis on thin films using quartz crystal microbalance with dissipation (QCM-D) demonstrated that the onset temperature of the enzymatic erosion was approximately 20 °C lower than the wet T(g) for all tested polymers. This new finding demonstrates that relatively high tensile strength polycarbonates can undergo enzymatic surface erosion. Moreover, it also sheds light on the connection between T(g) and enzymatic degradation and explains why few of the high strength polymers follow an enzyme-meditated degradation pathway.

  2. Demonstration of 6DOF Arc-mim/mm Control in the FCT Using Proba-3 Metrology and Control System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Implement in FCT avionics and attitude control architecture and software that enables order of magnitude increase in control capability for next-generation formation...

  3. Demonstration of a Plug and Play Approach to Satellite Thermal Control System Development Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mainstream is proposing a methodology to reduce the development time and cost, and improve the reliability of future thermal control systems for the next decade of...

  4. Novel controller design demonstration for vibration alleviation of helicopter rotor blades

    Science.gov (United States)

    Ulker, Fatma Demet; Nitzsche, Fred

    2012-04-01

    This paper presents an advanced controller design methodology for vibration alleviation of helicopter rotor sys- tems. Particularly, vibration alleviation in a forward ight regime where the rotor blades experience periodically varying aerodynamic loading was investigated. Controller synthesis was carried out under the time-periodic H2 and H∞ framework and the synthesis problem was solved based on both periodic Riccati and Linear Matrix Inequality (LMI) formulations. The closed-loop stability was analyzed using Floquet-Lyapunov theory, and the controller's performance was validated by closed-loop high-delity aeroelastic simulations. To validate the con- troller's performance an actively controlled trailing edge ap strategy was implemented. Computational cost was compared for both formulations.

  5. Development of a learning module using a virtual environment to demonstrate EMG and telerobotic control principles.

    Science.gov (United States)

    Patterson, P E

    2002-01-01

    A prototype system was developed for use as a teaching tool, allowing students to link EMG monitoring, data smoothing, robotic control, and neural network training within a rapid prototyping virtual environment (VE). The VE software allowed for the rapid development of scenarios and, when linked with EMG data input to a neural network, allowed the user to control an artificial world containing a virtual arm. Student teams then attempted to control the arm in the VE while performing the tasks by use of a neural network system they had specifically developed and trained using their own EMG signals. The results from their system were then translated into a form that enabled the control of a real robot. Students enjoyed the challenge and uniqueness of the module, and were enthusiastic about extending the concept to other areas of interest.

  6. Demonstration of Coherent-State Discrimination Using a Displacement-Controlled Photon-Number-Resolving Detector

    DEFF Research Database (Denmark)

    Wittmann, C.; Andersen, Ulrik Lund; Takeoka, M.

    2010-01-01

    We experimentally demonstrate a new measurement scheme for the discrimination of two coherent states. The measurement scheme is based on a displacement operation followed by a photon-number-resolving detector, and we show that it outperforms the standard homodyne detector which we, in addition...

  7. A Referential Communication Demonstration versus a Lecture-Only Control: Learning Benefits

    Science.gov (United States)

    Balch, William R.

    2014-01-01

    To evaluate a demonstration involving active and cooperative learning, 40 students in a cognitive psychology course and 132 students in an introductory psychology course completed a brief multiple-choice pretest on referential communication. Two days later, randomly assigned students either participated in a classroom referential communication…

  8. A Referential Communication Demonstration versus a Lecture-Only Control: Learning Benefits

    Science.gov (United States)

    Balch, William R.

    2014-01-01

    To evaluate a demonstration involving active and cooperative learning, 40 students in a cognitive psychology course and 132 students in an introductory psychology course completed a brief multiple-choice pretest on referential communication. Two days later, randomly assigned students either participated in a classroom referential communication…

  9. Actinides, accelerators and erosion

    OpenAIRE

    Fifield L. K.; Tims S.G.

    2012-01-01

    Fallout isotopes can be used as artificial tracers of soil erosion and sediment accumulation. The most commonly used isotope to date has been 137Cs. Concentrations of 137Cs are, however, significantly lower in the Southern Hemisphere, and furthermore have now declined to 35% of original values due to radioactive decay. As a consequence the future utility of 137Cs is limited in Australia, with many erosion applications becoming untenable within the next 20 years, and there is a need to replace...

  10. Effect of dentifrices against hydrochloric acid-induced erosion.

    Science.gov (United States)

    Messias, Danielle Cristine; Maeda, Fernando Akio; Turssi, Cecilia Pedroso; Serra, Mônica Campos

    2011-01-01

    This in vitro investigation assessed whether different dentifrices would be capable of controlling the enamel erosion progression caused by HCl. Sixty bovine enamel slabs were covered with acid-resistant varnish, except for a 2.5-mm2 circular area on the labial surface. According to a complete block design, the experimental units were immersed in HCl solution (pH 1.2; 0.1M). After storage in artificial saliva for 1 h, specimens (n = 15) were exposed to different dentifrices: Sensodyne Cool Gel (1100 ppm F), Sensodyne ProNamel (1450 ppm F), and PrevDent 5000 (5000 ppm F). The control group was immersed in deionised water. Following five cycles of erosive challenge, the slabs were prepared for porosity evaluation using solutions of copper sulfate and rubeanic acid. ANOVA demonstrated no difference in the enamel porosity as a function of the dentifrice employed (P = 0.5494). The damage caused by a simulated intrinsic erosive challenge seems unable to be controlled by fluoridated dentifrices, even when this ion is found in elevated concentrations.

  11. Predicting coastal cliff erosion using a Bayesian probabilistic model

    Science.gov (United States)

    Hapke, C.; Plant, N.

    2010-01-01

    Regional coastal cliff retreat is difficult to model due to the episodic nature of failures and the along-shore variability of retreat events. There is a growing demand, however, for predictive models that can be used to forecast areas vulnerable to coastal erosion hazards. Increasingly, probabilistic models are being employed that require data sets of high temporal density to define the joint probability density function that relates forcing variables (e.g. wave conditions) and initial conditions (e.g. cliff geometry) to erosion events. In this study we use a multi-parameter Bayesian network to investigate correlations between key variables that control and influence variations in cliff retreat processes. The network uses Bayesian statistical methods to estimate event probabilities using existing observations. Within this framework, we forecast the spatial distribution of cliff retreat along two stretches of cliffed coast in Southern California. The input parameters are the height and slope of the cliff, a descriptor of material strength based on the dominant cliff-forming lithology, and the long-term cliff erosion rate that represents prior behavior. The model is forced using predicted wave impact hours. Results demonstrate that the Bayesian approach is well-suited to the forward modeling of coastal cliff retreat, with the correct outcomes forecast in 70-90% of the modeled transects. The model also performs well in identifying specific locations of high cliff erosion, thus providing a foundation for hazard mapping. This approach can be employed to predict cliff erosion at time-scales ranging from storm events to the impacts of sea-level rise at the century-scale. ?? 2010.

  12. Potential for monitoring soil erosion features and soil erosion modeling components from remotely sensed data

    Science.gov (United States)

    Langran, K. J.

    1983-01-01

    Accurate estimates of soil erosion and its effects on soil productivity are essential in agricultural decision making and planning from the field scale to the national level. Erosion models have been primarily developed for designing erosion control systems, predicting sediment yield for reservoir design, predicting sediment transport, and simulating water quality. New models proposed are more comprehensive in that the necessary components (hydrology, erosion-sedimentation, nutrient cycling, tillage, etc.) are linked in a model appropriate for studying the erosion-productivity problem. Recent developments in remote sensing systems, such as Landsat Thematic Mapper, Shuttle Imaging Radar (SIR-B), etc., can contribute significantly to the future development and operational use of these models.

  13. Interated Intelligent Industrial Process Sensing and Control: Applied to and Demonstrated on Cupola Furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed Abdelrahman; roger Haggard; Wagdy Mahmoud; Kevin Moore; Denis Clark; Eric Larsen; Paul King

    2003-02-12

    The final goal of this project was the development of a system that is capable of controlling an industrial process effectively through the integration of information obtained through intelligent sensor fusion and intelligent control technologies. The industry of interest in this project was the metal casting industry as represented by cupola iron-melting furnaces. However, the developed technology is of generic type and hence applicable to several other industries. The system was divided into the following four major interacting components: 1. An object oriented generic architecture to integrate the developed software and hardware components @. Generic algorithms for intelligent signal analysis and sensor and model fusion 3. Development of supervisory structure for integration of intelligent sensor fusion data into the controller 4. Hardware implementation of intelligent signal analysis and fusion algorithms

  14. Erosion dynamics of a wet granular medium.

    Science.gov (United States)

    Lefebvre, Gautier; Jop, Pierre

    2013-09-01

    Liquid may give strong cohesion properties to a granular medium, and confer a solidlike behavior. We study the erosion of a fixed circular aggregate of wet granular matter subjected to a flow of dry grains inside a half-filled rotating drum. During the rotation, the dry grains flow around the fixed obstacle. We show that its diameter decreases linearly with time for low liquid content, as wet grains are pulled out of the aggregate. This erosion phenomenon is governed by the properties of the liquids. The erosion rate decreases exponentially with the surface tension while it depends on the viscosity to the power -1. We propose a model based on the force fluctuations arising inside the flow, explaining both dependencies: The capillary force acts as a threshold and the viscosity controls the erosion time scale. We also provide experiments using different flowing grains, confirming our model.

  15. Precommercial Stocking Control of Coast Redwood at Caspar Creek, Jackson Demonstration State Forest

    Science.gov (United States)

    James Lindquist

    2007-01-01

    Regeneration of coast redwood by stump sprouting often results in a stand condition that is very dense. A precommercial thinning of redwood sprouts allows managers to select trees and spacing that can best utilize the productivity of the site. The study of five thinning treatments with an unthinned control was initiated on a 19-year old third growth stand. Treatments...

  16. A Mycobacterium tuberculosis cluster demonstrating the use of genotyping in urban tuberculosis control

    NARCIS (Netherlands)

    G. de Vries (Gerard); R.M. van Hest (Reinier); C.C.A. Burdo (Conny); D. van Soolingen (Dick); J.H. Richardus (Jan Hendrik)

    2009-01-01

    textabstractBackground: DNA fingerprinting of Mycobacterium tuberculosis isolates offers better opportunities to study links between tuberculosis (TB) cases and can highlight relevant issues in urban TB control in low-endemic countries. Methods: A medium-sized molecular cluster of TB cases with iden

  17. Demonstration of leapfrogging for implementing nonlinear model predictive control on a heat exchanger.

    Science.gov (United States)

    Sridhar, Upasana Manimegalai; Govindarajan, Anand; Rhinehart, R Russell

    2016-01-01

    This work reveals the applicability of a relatively new optimization technique, Leapfrogging, for both nonlinear regression modeling and a methodology for nonlinear model-predictive control. Both are relatively simple, yet effective. The application on a nonlinear, pilot-scale, shell-and-tube heat exchanger reveals practicability of the techniques.

  18. Methodological demonstration of laser beam pointing control for space gravitational wave detection missions.

    Science.gov (United States)

    Dong, Yu-Hui; Liu, He-Shan; Luo, Zi-Ren; Li, Yu-Qiong; Jin, Gang

    2014-07-01

    In space laser interferometer gravitational wave (G.W.) detection missions, the stability of the laser beam pointing direction has to be kept at 10 nrad/√Hz. Otherwise, the beam pointing jitter noise will dominate the noise budget and make the detection of G.W. impossible. Disturbed by the residue non-conservative forces, the fluctuation of the laser beam pointing direction could be a few μrad/√Hz at frequencies from 0.1 mHz to 10 Hz. Therefore, the laser beam pointing control system is an essential requirement for those space G.W. detection missions. An on-ground test of such beam pointing control system is performed, where the Differential Wave-front Sensing technique is used to sense the beams pointing jitter. An active controlled steering mirror is employed to adjust the beam pointing direction to compensate the jitter. The experimental result shows that the pointing control system can be used for very large dynamic range up to 5 μrad. At the interested frequencies of space G.W. detection missions, between 1 mHz and 1 Hz, beam pointing stability of 6 nrad/√Hz is achieved.

  19. Controlled laboratory challenge demonstrates substantial additive genetic variation in resistance to Streptococcus iniae in Nile tilapia

    Science.gov (United States)

    Streptococcus iniae is an etiologic agent of streptococcal disease in tilapia and is one of several Streptococcus spp. that negatively impact worldwide tilapia production. Methods for the prevention and control of S. iniae include vaccines, management strategies, and antibiotics. An alternative and ...

  20. Conventional and anti-erosion fluoride toothpastes: effect on enamel erosion and erosion-abrasion.

    Science.gov (United States)

    Ganss, C; Lussi, A; Grunau, O; Klimek, J; Schlueter, N

    2011-01-01

    New toothpastes with anti-erosion claims are marketed, but little is known about their effectiveness. This study investigates these products in comparison with various conventional NaF toothpastes and tin-containing products with respect to their erosion protection/abrasion prevention properties. In experiment 1, samples were demineralised (10 days, 6 × 2 min/day; citric acid, pH 2.4), exposed to toothpaste slurries (2 × 2 min/day) and intermittently stored in a mineral salt solution. In experiment 2, samples were additionally brushed for 15 s during the slurry immersion time. Study products were 8 conventional NaF toothpastes (1,400-1,490 ppm F), 4 formulations with anti-erosion claims (2 F toothpastes: NaF + KNO(3) and NaF + hydroxyapatite; and 2 F-free toothpastes: zinc-carbonate-hydroxyapatite, and chitosan) and 2 Sn-containing products (toothpaste: 3,436 ppm Sn, 1,450 ppm F as SnF(2)/NaF; gel: 970 ppm F, 3,030 ppm Sn as SnF(2)). A mouth rinse (500 ppm F as AmF/NaF, 800 ppm Sn as SnCl(2)) was the positive control. Tissue loss was quantified profilometrically. In experiment 1, most NaF toothpastes and 1 F-free formulation reduced tissue loss significantly (between 19 and 42%); the Sn-containing formulations were the most effective (toothpaste and gel 55 and 78% reduction, respectively). In experiment 2, only 4 NaF toothpastes revealed significant effects compared to the F-free control (reduction between 29 and 37%); the F-free special preparations and the Sn toothpaste had no significant effect. The Sn gel (reduction 75%) revealed the best result. Conventional NaF toothpastes reduced the erosive tissue loss, but had limited efficacy regarding the prevention of brushing abrasion. The special formulations were not superior, or were even less effective.

  1. LONG-TERM DEMONSTRATION OF SORBENT ENHANCEMENT ADDITIVE TECHNOLOGY FOR MERCURY CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    Jason D. Laumb; Dennis L. Laudal; Grant E. Dunham; John P. Kay; Christopher L. Martin; Jeffrey S. Thompson; Nicholas B. Lentz; Alexander Azenkeng; Kevin C. Galbreath; Lucinda L. Hamre

    2011-05-27

    Long-term demonstration tests of advanced sorbent enhancement additive (SEA) technologies have been completed at five coal-fired power plants. The targeted removal rate was 90% from baseline conditions at all five stations. The plants included Hawthorn Unit 5, Mill Creek Unit 4, San Miguel Unit 1, Centralia Unit 2, and Hoot Lake Unit 2. The materials tested included powdered activated carbon, treated carbon, scrubber additives, and SEAs. In only one case (San Miguel) was >90% removal not attainable. The reemission of mercury from the scrubber at this facility prevented >90% capture.

  2. Ice-sheet control of continental erosion in central and southern Chile (36°-41°S) over the last 30,000 years

    Science.gov (United States)

    Muratli, Jesse M.; Chase, Zanna; McManus, James; Mix, Alan

    2010-11-01

    Bulk sediment chemistry from three Chilean continental margin Ocean Drilling Program sites constrains regional continental erosion over the past 30,000 years. Sediments from thirteen rivers that drain the (mostly igneous) Andes and the (mostly metamorphic) Coast Range, along with existing rock chemistry datasets, define terrestrial provenance for the continental margin sediments. Andean river sediments have high Mg/Al relative to Coast-Range river sediments. Near 36°S, marine sediments have high-Mg/Al (i.e. more Andean) sources during the last glacial period, and lower-Mg/Al (less Andean) sources during the Holocene. Near 41°S a Ti-rich source, likely from coast-range igneous intrusions, is prevalent during Holocene time, whereas high-Mg/Al Andean sources are more prevalent during the last glacial period. We infer that there is a dominant ice-sheet control of sediment sources. At 36°S, Andean-sourced sediment decreased as Andean mountain glaciers retreated after ˜17.6 ka, coincident with local oceanic warming and southward retreat of the Patagonian Forest and, by inference, westerly winds. At 41°S Andean sediment dominance peaks and then rapidly declines at ˜19 ka, coincident with local oceanic warming and the earliest deglacial sea-level rise. We hypothesize that this decreased flux of Andean material in the south is related to rapid retreat of the marine-based portion of the Patagonian Ice Sheet in response to global sea-level rise, as the resulting flooding of the southern portion of the Central Valley created a sink for Andean sediments in this region. Reversal of the decreasing deglacial Mg/Al trend at 41°S from 14.5 to 13.0 ka is consistent with a brief re-advance of the Patagonian ice sheet coincident with the Antarctic Cold Reversal.

  3. Normalized performance and load data for the deepwind demonstrator in controlled conditions

    Directory of Open Access Journals (Sweden)

    L. Battisti

    2016-09-01

    Full Text Available Performance and load normalized coefficients, deriving from an experimental campaign of measurements conducted at the large scale wind tunnel of the Politecnico di Milano (Italy, are presented with the aim of providing useful benchmark data for the validation of numerical codes. Rough data, derived from real scale measurements on a three-bladed Troposkien vertical-axis wind turbine, are manipulated in a convenient form to be easily compared with the typical outputs provided by simulation codes. The here proposed data complement and support the measurements already presented in “Wind Tunnel Testing of the DeepWind Demonstrator in Design and Tilted Operating Conditions” (Battisti et al., 2016 [1].

  4. Demonstration of spectral correlation control in a source of polarization entangled photon pairs at telecom wavelength

    CERN Document Server

    Lutz, Thomas; Jennewein, Thomas

    2013-01-01

    Spectrally correlated photon pairs can be used to improve performance of long range fiber based quantum communication protocols. We present a source based on spontaneous parametric down-conversion producing polarization entangled photons without spectral filtering. In addition, the spectral correlation within the photon pair can be controlled by changing the pump pulse duration or coupled spatial modes characteristics. The spectral and polarization correlations were characterized. The generated photon pairs feature both positive spectral correlations, no correlations, or negative correlations and polarization entanglement with the fidelity as high as 0.97 (no background subtraction) with the expected Bell state.

  5. Control Demonstration of a Thin Deformable In-Plane Actuated Mirror

    Science.gov (United States)

    2006-03-01

    ControlDesktop saves each desired variable as a structured array. This allows all post-processing to be completed within Matlab R©. Movies of the...DAC blocks are dSpace R© coded blocks that provide analog signal to the dSpace R© signal generator. These seven blocks correspond to the seven...block: Under the rx parameters tab, set the number of bytes to 297. • In the S-function − Builder2 block: Under the data properties tab, change the

  6. Demonstration of sufficient control for two rounds of quantum error correction in a solid state ensemble quantum information processor

    CERN Document Server

    Moussa, Osama; Ryan, Colm A; Laflamme, Raymond

    2011-01-01

    We report the implementation of a 3-qubit quantum error correction code (QECC) on a quantum information processor realized by the magnetic resonance of Carbon nuclei in a single crystal of Malonic Acid. The code corrects for phase errors induced on the qubits due to imperfect decoupling of the magnetic environment represented by nearby spins, as well as unwanted evolution under the internal Hamiltonian. We also experimentally demonstrate sufficiently high fidelity control to implement two rounds of quantum error correction. This is a demonstration of state-of-the-art control in solid state nuclear magnetic resonance, a leading test-bed for the implementation of quantum algorithms.

  7. Demonstration of sufficient control for two rounds of quantum error correction in a solid state ensemble quantum information processor.

    Science.gov (United States)

    Moussa, Osama; Baugh, Jonathan; Ryan, Colm A; Laflamme, Raymond

    2011-10-14

    We report the implementation of a 3-qubit quantum error-correction code on a quantum information processor realized by the magnetic resonance of carbon nuclei in a single crystal of malonic acid. The code corrects for phase errors induced on the qubits due to imperfect decoupling of the magnetic environment represented by nearby spins, as well as unwanted evolution under the internal Hamiltonian. We also experimentally demonstrate sufficiently high-fidelity control to implement two rounds of quantum error correction. This is a demonstration of state-of-the-art control in solid state nuclear magnetic resonance, a leading test bed for the implementation of quantum algorithms.

  8. A Mycobacterium tuberculosis cluster demonstrating the use of genotyping in urban tuberculosis control

    Directory of Open Access Journals (Sweden)

    Burdo Conny CA

    2009-09-01

    Full Text Available Abstract Background DNA fingerprinting of Mycobacterium tuberculosis isolates offers better opportunities to study links between tuberculosis (TB cases and can highlight relevant issues in urban TB control in low-endemic countries. Methods A medium-sized molecular cluster of TB cases with identical DNA fingerprints was used for the development of a visual presentation of epidemiologic links between cases. Results Of 32 cases, 17 (53% were linked to the index case, and 11 (34% to a secondary case. The remaining four (13% could not be linked and were classified as possibly caused by the index patient. Of the 21 cases related to the index case, TB developed within one year of the index diagnosis in 11 patients (52%, within one to two years in four patients (19%, and within two to five years in six patients (29%. Conclusion Cluster analysis underscored several issues for TB control in an urban setting, such as the recognition of the outbreak, the importance of reinfections, the impact of delayed diagnosis, the contribution of pub-related transmissions and its value for decision-making to extend contact investigations. Visualising cases in a cluster diagram was particularly useful in finding transmission locations and the similarities and links between patients.

  9. Fractal Tectonics and Erosion

    Science.gov (United States)

    Turcotte, Donald L.

    Tectonic processes build landforms that are subsequently destroyed by erosional processes. Landforms exhibit fractal statistics in a variety of ways; examples include (1) lengths of coast lines; (2) number-size statistics of lakes and islands; (3) spectral behavior of topography and bathymetry both globally and locally; and (4) branching statistics of drainage networks. Erosional processes are dominant in the development of many landforms on this planet, but similar fractal statistics are also applicable to the surface of Venus where minimal erosion has occurred. A number of dynamical systems models for landforms have been proposed, including (1) cellular automata; (2) diffusion limited aggregation; (3) self-avoiding percolation; and (4) advective-diffusion equations. The fractal statistics and validity of these models will be discussed. Earthquakes also exhibit fractal statistics. The frequency-magnitude statistics of earthquakes satisfy the fractal Gutenberg-Richter relation both globally and locally. Earthquakes are believed to be a classic example of self-organized criticality. One model for earthquakes utilizes interacting slider-blocks. These slider block models have been shown to behave chaotically and to exhibit self-organized criticality. The applicability of these models will be discussed and alternative approaches will be presented. Fragmentation has been demonstrated to produce fractal statistics in many cases. Comminution is one model for fragmentation that yields fractal statistics. It has been proposed that comminution is also responsible for much of the deformation in the earth's crust. The brittle disruption of the crust and the resulting earthquakes present an integrated problem with many fractal aspects.

  10. A randomized controlled trial demonstrates that a novel closed-loop propofol system performs better hypnosis control than manual administration.

    Science.gov (United States)

    Hemmerling, Thomas M; Charabati, Samer; Zaouter, Cedrick; Minardi, Carmelo; Mathieu, Pierre A

    2010-08-01

    The purpose of this randomized control trial was to determine the performance of a novel rule-based adaptive closed-loop system for propofol administration using the bispectral index (BIS(R)) and to compare the system's performance with manual administration. The effectiveness of the closed-loop system to maintain BIS close to a target of 45 was determined and compared with manual administration. After Institutional Review Board approval and written consent, 40 patients undergoing major surgery in a tertiary university hospital were allocated to two groups using computer-generated block randomization. In the Closed-loop group (n = 20), closed-loop control was used to maintain anesthesia at a target BIS of 45, and in the Control group (n = 20), propofol was administered manually to maintain the same BIS target. To evaluate each technique's performance in maintaining a steady level of hypnosis, the BIS values obtained during the surgical procedure were stratified into four clinical performance categories relative to the target BIS: 30% defined as excellent, good, poor, or inadequate control of hypnosis, respectively. The controller performance was compared using Varvel's controller performance indices. Data were compared using Fisher's exact test and the Mann-Whitney U test, P performance error and the median absolute performance error were significantly lower in the Closed-loop group compared with the Control group (-1.1 +/- 5.3% vs -10.7 +/- 13.1%; P = 0.004 and 9.1 +/- 1.9% vs 15.7 +/- 7.4%; P performance than manual administration of propofol. (Clinical Trials gov. NCT 01019746).

  11. Investigation and Demonstration of Dry Carbon-Based Sorbent Injection for Mercury Control

    Energy Technology Data Exchange (ETDEWEB)

    Jim Butz; Terry Hunt

    2005-11-01

    Public Service Company of Colorado and ADA Technologies, Inc. have performed a study of the injection of activated carbon for the removal of vapor-phase mercury from coal-fired flue gas streams. The project was completed under contract to the US Department of Energy's National Energy Technology Laboratory, with contributions from EPRI and Public Service Company. The prime contractor for the project was Public Service Company, with ADA Technologies as the major subcontractor providing technical support to all aspects of the project. The research and development effort was conducted in two phases. In Phase I a pilot facility was fabricated and tests were performed using dry carbon-based sorbent injection for mercury control on a coal-fired flue gas slipstream extracted from an operating power plant. Phase II was designed to move carbon injection technology towards commercial application on coal-fired power plants by addressing key reliability and operability concerns. Phase II field work included further development work with the Phase I pilot and mercury measurements on several of PSCo's coal-fired generating units. In addition, tests were run on collected sorbent plus fly ash to evaluate the impact of the activated carbon sorbent on the disposal of fly ash. An economic analysis was performed where pilot plant test data was used to develop a model to predict estimated costs of mercury removal from plants burning western coals. Testing in the pilot plant was undertaken to quantify the effects of plant configuration, flue gas temperature, and activated carbon injection rate on mercury removal. All three variables were found to significantly impact the mercury removal efficiency in the pilot. The trends were clear: mercury removal rates increased with decreasing flue gas temperature and with increasing carbon injection rates. Mercury removal was much more efficient with reverse-gas and pulse-jet baghouse configurations than with an ESP as the particulate

  12. Optimization of sand control liner designs for Leismer SAGD demonstration horizontal wells

    Energy Technology Data Exchange (ETDEWEB)

    Xie, J. [C-FER Technologies, Edmonton, AB (Canada); Solvoll, T.A. [StatoilHydro Canada Ltd., Calgary, AB (Canada)

    2009-07-01

    The Leismer demonstration project has been planned as part of the larger Kai Kos Dehseh oilsands project owned by StatoilHydro. The project will consist initially of 23 horizontal well pairs distributed over 4 wellpads. Slotted liner and screen designs for the Leismer steam assisted gravity drainage (SAGD) wells were presented in this study. Finite element analyses were conducted to study the impact of the liner's weight and open flow area (OFA) on system performance. The model considered elastic-plastic material responses and deformations that might occur during SAGD applications. The criteria investigated in this study included collapse capacity; installation load limits; thermal strain loading; and slot or wire-spacing opening and closings. The analysis showed that liner weight and slot density have a significant impact on slotted liner performance. It was concluded that the designs provide optimized open flow areas (OFA), acceptable sand screen functionality, and enhanced structural capacities to sustain installation and operational loads over the lifetime of both producer and injector wells. 4 refs., 15 figs.

  13. Instrumentation and process control for fossil demonstration plants. Quarterly technical progress report, October--December 1976

    Energy Technology Data Exchange (ETDEWEB)

    LeSage, L. G.; O' Fallon, N. M; Bump, T. R.; Cohn, C. E.; Doering, R. W.; Duffey, D.; Kirsch,; Lipinski, W. C.; Managan, W. W.; Porges, K. G.; Raptis, A. C.

    1977-01-01

    The final report of the state-of-the-art study of instrumentation for process control and safety in large-scale coal conversion and fluidized-bed combustion systems was distributed in November. A conceptual design for the Solids/Gas Flow Test Facility has been initiated, the major components identified, and vendors located. Work on acoustic flow measurement has included theoretical feasibility studies of acoustic/ultrasonic techniques for mass-flow measurements of slurries and solid/gas media. Initial planning was conducted to establish a laboratory facility necessary to verify theoretical findings. A survey of the literature relating to capacitive measurements was begun to provide a basis for conceptual designs and preliminary bench tests of the feasibility of these designs. Conceptual design of a capacitive on-line solids density measuring device and calculations to select the type of system for initial feasibility tests were carried out. Preliminary tests of neutron capture gamma analysis for on-line elemental composition of liquid and solid streams in coal plants indicate that most coal elements can be detected quantitatively through the pipe walls. A computer program for peak-fitting in the gamma spectrum was modified for requirements of this work. A literature search was started to determine the state-of-the-art in dynamic process modeling of fossil energy system components, physical property models, and process control models. A partial review of abstracts from a computerized literature search has identified over 50 references having possible application to process analysis activities in this program.

  14. An empirical approach to estimate soil erosion risk in Spain.

    Science.gov (United States)

    Martín-Fernández, Luis; Martínez-Núñez, Margarita

    2011-08-01

    Soil erosion is one of the most important factors in land degradation and influences desertification worldwide. In 2001, the Spanish Ministry of the Environment launched the 'National Inventory of Soil Erosion (INES) 2002-2012' to study the process of soil erosion in Spain. The aim of the current article is to assess the usefulness of this National Inventory as an instrument of control, measurement and monitoring of soil erosion in Spain. The methodology and main features of this National Inventory are described in detail. The results achieved as of the end of May 2010 are presented, together with an explanation of the utility of the Inventory as a tool for planning forest hydrologic restoration, soil protection, erosion control, and protection against desertification. Finally, the authors make a comparative analysis of similar initiatives for assessing soil erosion in other countries at the national and European levels.

  15. Variable Cycle Engine Control System Definition Study. Turbine Engine Technology Demonstrator Component Development Program, Project 668A. Controls Development Program

    Science.gov (United States)

    1976-03-01

    with a contvol system was developed along with cOMUtet.-ed optimi.-ation ard conetraint proedure... to e-totlish optimal enine jam• ?a. ... O1 • j1.4St 1...self-test and diagnostic features of the controller software . It should be noted from a systems concept that failure detection applies to both the...deve’..., and validation of software for implementing the final control mode for the J.:-’on-, strator test stand running. The test program also

  16. Demonstration of the suitability of GPUs for AO real-time control at ELT scales

    Science.gov (United States)

    Bitenc, Urban; Basden, Alastair G.; Dipper, Nigel A.; Myers, Richard M.

    2016-07-01

    We have implemented the full AO data-processing pipeline on Graphics Processing Units (GPUs), within the framework of Durham AO Real-time Controller (DARC). The wavefront sensor images are copied from the CPU memory to the GPU memory. The GPU processes the data and the DM commands are copied back to the CPU. For a SCAO system of 80x80 subapertures, the rate achieved on a single GPU is about 700 frames per second (fps). This increases to 1100 fps (1565 fps) if we use two (four) GPUs. Jitter exhibits a distribution with the root-mean-square value of 20 μs-30 μs and a negligible number of outliers. The increase in latency due to the pixel data copying from the CPU to the GPU has been reduced to the minimum by copying the data in parallel to processing them. An alternative solution in which the data would be moved from the camera directly to the GPU, without CPU involvement, could be about 10%-20% faster. We have also implemented the correlation centroiding algorithm, which - when used - reduces the frame rate by about a factor of 2-3.

  17. Gastroesophageal Reflux is Not Associated with Dental Erosion in Children

    Science.gov (United States)

    Wild, Yvette K.; Heyman, Melvin B.; Vittinghoff, Eric; Dalal, Deepal H.; Wojcicki, Janet M.; Clark, Ann L.; Rechmann, Beate; Rechmann, Peter

    2011-01-01

    Background & Aims Dental erosion is a complication of gastroesophageal reflux (GER) in adults; in children, it is not clear if GER has a role in dental pathologic conditions. Dietary intake, oral hygiene, high bacterial load, and decreased salivary flow might contribute independently to GER development or dental erosion, but their potential involvement in dental erosion from GER is not understood. We investigated the prevalence of dental erosion among children with and without GER symptoms, and whether salivary flow rate or bacterial load contribute to location-specific dental erosion. Methods We performed a cross-sectional study of 59 children (ages 9–17 y) with symptoms of GER and 20 asymptomatic children (controls); all completed a questionnaire on dietary exposure. Permanent teeth were examined for erosion into dentin, erosion locations, and affected surfaces. The dentist was not aware of GER status, nor was the gastroenterologist aware of dental status. Stimulated salivary flow was measured and salivary bacterial load was calculated for total bacteria, Streptococcus mutans and Lactobacilli. Results Controlling for age, dietary intake, and oral hygiene, there was no association between GER symptoms and dental erosion, by tooth location or affected surface. Salivary flow did not correlate with GER symptoms or erosion. Erosion location and surface were independent of total bacteria and levels of Streptococcus mutans and Lactobacilli. Conclusions Location-specific dental erosion is not associated with GER, salivary flow, or bacterial load. Prospective studies are required to determine the pathogenesis of GER-associated dental erosion and the relationship between dental caries to GER and dental erosion. PMID:21820389

  18. First demonstration and performance of an injection locked continuous wave magnetron to phase control a superconducting cavity

    Energy Technology Data Exchange (ETDEWEB)

    A.C. Dexter, G. Burt, R.G. Carter, I. Tahir, H. Wang, K. Davis, R. Rimmer

    2011-03-01

    The applications of magnetrons to high power proton and cw electron linacs are discussed. An experiment is described where a 2.45 GHz magnetron has been used to drive a single cell superconducting cavity. With the magnetron injection locked, a modest phase control accuracy of 0.95° rms has been demonstrated. Factors limiting performance have been identified.

  19. Ecological site-based assessments of wind and water erosion: informing accelerated soil erosion management in rangelands

    Science.gov (United States)

    Webb, Nicholas P.; Herrick, Jeffrey E.; Duniway, Michael C.

    2014-01-01

    Accelerated soil erosion occurs when anthropogenic processes modify soil, vegetation or climatic conditions causing erosion rates at a location to exceed their natural variability. Identifying where and when accelerated erosion occurs is a critical first step toward its effective management. Here we explore how erosion assessments structured in the context of ecological sites (a land classification based on soils, landscape setting and ecological potential) and their vegetation states (plant assemblages that may change due to management) can inform systems for reducing accelerated soil erosion in rangelands. We evaluated aeolian horizontal sediment flux and fluvial sediment erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Across the ecological sites, plots in shrub-encroached and shrub-dominated vegetation states were consistently susceptible to aeolian sediment flux and fluvial sediment erosion. Both processes were found to be highly variable for grassland and grass-succulent states across the ecological sites at the plot scale (0.25 Ha). We identify vegetation thresholds that define cover levels below which rapid (exponential) increases in aeolian sediment flux and fluvial sediment erosion occur across the ecological sites and vegetation states. Aeolian sediment flux and fluvial erosion in the study area can be effectively controlled when bare ground cover is 100 cm in length is less than ~35%. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of areas to erosion. Land use impacts that are constrained within the range of natural variability should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds identified here will enable identification of areas susceptible to accelerated soil erosion and the development of

  20. Can erosion control structures in large dryland arroyo channels lead to resilient riparian and cienega restoration? Observations from LiDAR, monitoring and modeling at Rancho San Bernardino, Sonora, MX

    Science.gov (United States)

    DeLong, S.; Henderson, W. M.

    2012-12-01

    The use of erosion control structures to mitigate or even reverse erosion and to restore ecological function along dryland channels (arroyos and gullies) has led to a long list of both successful and failed restoration efforts. We propose that successful implementation of "engineering" approaches to fluvial restoration that include in-channel control structures require either a quantitative approach to design (by scientists and engineers), or intimate on-the-ground knowledge, local observation, and a commitment to adapt and maintain restoration efforts in response to landscape change (by local land managers), or both. We further propose that the biophysical interactions among engineering, sedimentation, flood hydrology and vegetation reestablishment are what determine resilience to destructive extreme events that commonly cause erosion control structure failure. Our insights come from comprehensive monitoring of a remarkable experiment underway at Ranch San Bernardino, Sonora, MX. At this site, private landowners are working to restore ecosystem function to riparian corridors and former cieñega wetlands using cessation of grazing; vegetation planting; upland grass restoration; large scale rock gabions (up to 100 m wide) to encourage local sediment deposition and water storage; and large earthen berms (up to 900 m wide) with cement spillways that form reservoirs that fill rapidly with water and sediment. Well-planned and managed erosion control structures have been used elsewhere successfully in smaller gully networks, but we are unaware of a comparable attempt to use gabions and berms for the sole purpose of ecological restoration along >10 km of arroyo channels draining watersheds on the order of ~400 km2 and larger. We present an approach to monitoring the efficacy of arroyo channel restoration using terrestrial and airborne LiDAR, remote sensing, streamflow monitoring, shallow groundwater monitoring, hydrological modeling and field observation. Our methods

  1. Evaluation of Erosion Resistance of Advanced Turbine Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Kuczmarski, Maria A.; Miller, Robert A.; Cuy, Michael D.

    2007-01-01

    The erosion resistant turbine thermal barrier coating system is critical to aircraft engine performance and durability. By demonstrating advanced turbine material testing capabilities, we will be able to facilitate the critical turbine coating and subcomponent development and help establish advanced erosion-resistant turbine airfoil thermal barrier coatings design tools. The objective of this work is to determine erosion resistance of advanced thermal barrier coating systems under simulated engine erosion and/or thermal gradient environments, validating advanced turbine airfoil thermal barrier coating systems based on nano-tetragonal phase toughening design approaches.

  2. 10-daily soil erosion modelling over sub-Saharan Africa.

    Science.gov (United States)

    Symeonakis, Elias; Drake, Nick

    2010-02-01

    Soil erosion is considered to be one of the greatest environmental problems of sub-Saharan Africa. This paper investigates the advantages and disadvantages of modelling soil erosion at the continental scale and suggests an operational methodology for mapping and quantifying 10-daily water runoff and soil erosion over this scale using remote sensing data in a geographical information system framework. An attempt is made to compare the estimates of this study with general data on the severity of soil erosion over Africa and with measured rates of soil loss at different locations over the continent. The results show that the measured and estimated rates of erosion are in some areas very similar and in general within the same order of magnitude. The importance and the potential of using the soil erosion estimates with simple models and easily accessible free data for various continental-scale environmental applications are also demonstrated.

  3. Hillslope soil erosion and runoff model for natural rainfall events

    Institute of Scientific and Technical Information of China (English)

    Zhanyu Zhang; Guohua Zhang; Changqing Zuo; Xiaoyu Pi

    2008-01-01

    By using the momentum theorem and water balance principle, basic equations of slope runoff were derived, soil erosion by raindrop splash and runoff were discussed and a model was established for decribing hillslope soil erosion processes. The numerical solution of the model was obtained by adopting the Preissmann format and considering the common solution-determining conditions, from which not only the runoff and soil erosion but also their processes can be described. The model was validated by ten groups of observation data of Soil Conservation Ecological Science and Technology Demonstration Park of Jiangxi Province. Comparisons show that the maximum relative error between simulation and experimental data is about 10.98% for total runoff and 15% for total erosion, 5.2% for runoff process and 6.1% for erosion process, indicating that the model is conceptually realistic and reliable and offers a feasible approach for further studies on the soil erosion process.

  4. Clinical studies of dental erosion and erosive wear

    National Research Council Canada - National Science Library

    Huysmans, M.C.D.N.J.M; Chew, H.P; Ellwood, R.P

    2011-01-01

    We define erosion as a partial demineralisation of enamel or dentine by intrinsic or extrinsic acids and erosive tooth wear as the accelerated loss of dental hard tissue through the combined effect...

  5. Erosivity, surface runoff, and soil erosion estimation using GIS-coupled runoff-erosion model in the Mamuaba catchment, Brazil.

    Science.gov (United States)

    Marques da Silva, Richarde; Guimarães Santos, Celso Augusto; Carneiro de Lima Silva, Valeriano; Pereira e Silva, Leonardo

    2013-11-01

    This study evaluates erosivity, surface runoff generation, and soil erosion rates for Mamuaba catchment, sub-catchment of Gramame River basin (Brazil) by using the ArcView Soil and Water Assessment Tool (AvSWAT) model. Calibration and validation of the model was performed on monthly basis, and it could simulate surface runoff and soil erosion to a good level of accuracy. Daily rainfall data between 1969 and 1989 from six rain gauges were used, and the monthly rainfall erosivity of each station was computed for all the studied years. In order to evaluate the calibration and validation of the model, monthly runoff data between January 1978 and April 1982 from one runoff gauge were used as well. The estimated soil loss rates were also realistic when compared to what can be observed in the field and to results from previous studies around of catchment. The long-term average soil loss was estimated at 9.4 t ha(-1) year(-1); most of the area of the catchment (60%) was predicted to suffer from a low- to moderate-erosion risk (catchment, the soil erosion was estimated to exceed > 12 t ha(-1) year(-1). Expectedly, estimated soil loss was significantly correlated with measured rainfall and simulated surface runoff. Based on the estimated soil loss rates, the catchment was divided into four priority categories (low, moderate, high and very high) for conservation intervention. The study demonstrates that the AvSWAT model provides a useful tool for soil erosion assessment from catchments and facilitates the planning for a sustainable land management in northeastern Brazil.

  6. An Experimental Simulation Method of Erosion Process on Gully Erosion in Loess Plateau in China

    Science.gov (United States)

    Gao, Jianen; Zhang, Yuanxing

    2017-04-01

    verified by the measured data of the prototype. And it was an effective method in researching the gully erosion generation, development, evolution process and the field gully erosion control through laboratory experiment.

  7. Quantifying modern and ancient drainage basin erosion with detrital thermochronology

    Science.gov (United States)

    Ehlers, T. A.; Stock, G. M.; Rahl, J. M.; Farley, K. A.; van der Pluijm, B. A.

    2006-12-01

    rates between 0.2-1.0 mm/yr, we found that erosion rates calculated using simplifying assumptions of thermal steady-state can be in error by -25 to 100%. Comparison of model results to published white mica 40Ar/39Ar and zircon fission track cooling ages from syntectonic deposits in the Nanga Parbat region, Himalaya, demonstrates that the model can discriminate between scenarios of steady-state erosion and an acceleration or deceleration in erosion. In this example, we found erosion rates increased over the past 20 Ma from 1.0 mm/yr to 1.5-2.0 mm/yr. Taken together, these two applications demonstrate: (1) catchment erosion can be spatially variable in neighboring catchments, and future work should focus on understanding the efficiency of different geomorphic processes that supply sediment to rivers; and (2) caution should be used when assuming steady-state erosion from detrital thermochronometer data.

  8. A new noise erosion operator for anisotropic diffusion

    Institute of Scientific and Technical Information of China (English)

    Chao Cai(蔡超); Mingyue Ding(丁名跃); Chengping Zhou(周成平); Tianxu Zhang(张天序)

    2004-01-01

    A noise erosion operator based on partial differential equation (PDE) is introduced, which has an excellent ability of noise removal and edge preservation for two-dimensional (2D) gradient data. The operator is applied to estimate a new diffusion coefficient. Experimental results demonstrate that anisotropic diffusion based on this new erosion operator can efficiently reduce noise and sharpen object boundaries.

  9. Bentonite erosion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Birgersson, Martin; Boergesson, Lennart; Hedstroem, Magnus; Karnland, Ola; Nilsson, Ulf (Clay Technology AB, Lund (Sweden))

    2009-12-15

    Low saline water may reach KBS-3 repository depth, e.g. during periods of glaciation. Under such aqueous conditions, the montmorillonite part of the bentonite buffer might transform into a sol and thereby be transported away with flowing water in fractures. The primary aim with this report is to improve the understanding of the basic principles for this possible montmorillonite particle release. The report includes experimental and theoretical work performed at Clay Technology. Natural bentonite and ion-exchanged purified montmorillonite from three different geographical origins, Wyoming (U.S.), Milos (Greece) and Kutch (India) have been studied. Experimental and/or theoretical investigations have been performed with respect to: - Free swelling ability; - Rheological properties; - Rate of bentonite loss into fractures; - Filtering; - Ion exchange; - Sol formation ability; - Ion diffusion; - Mass loss due to erosion. The performed erosion experiments show that erosion does not occur in a mixed calcium/sodium montmorillonite with at least 20% calcium in exchange positions, when the external solution contains above 4 mM charge equivalents. This result is in agreement with the presented conceptual view of sol formation and measured equilibrium properties in mixed calcium/sodium montmorillonite. The findings imply that the buffer will be stable for non-glacial conditions. However, erosion due to sol formation cannot be ruled out for glacial conditions.

  10. SEDIMENTATION AND EROSION STUDIES

    Institute of Scientific and Technical Information of China (English)

    Chih Ted YANG

    2005-01-01

    @@ The river systems observed today is the cumulative result of surface, rill, and gully erosion, and sediment transport, scour, and deposition. The divisions of approach between these two related areas are man-made, and are not based on sound science. Most of the erosion studies are done by geologists and agricultural engineers who are concerned of the surface, rill, and gully erosion and the loss of agricultural land productivity. Hydraulic engineers are more interested in the study of sediment transport, scour, and deposition, and their impacts on river engineering and hydraulic structures in rivers and reservoirs. Erosion studies are often based on empirical relationships or field data to determinate the annual sediment yield from a watershed. On the other hand, hydraulic engineers focus their attention on solving equations based on assumed initial and boundary conditions with a time scale of days, hours, or seconds. Both approaches have their complementary strengths and weaknesses. It is important to provide a forum for specialists in both areas to communicate, exchange ideas, and learn from each other.

  11. Erosion of dust aggregates

    CERN Document Server

    Seizinger, Alexander; Kley, Wilhelm

    2013-01-01

    Aims: The aim of this work is to gain a deeper insight into how much different aggregate types are affected by erosion. Especially, it is important to study the influence of the velocity of the impacting projectiles. We also want to provide models for dust growth in protoplanetary disks with simple recipes to account for erosion effects. Methods: To study the erosion of dust aggregates we employed a molecular dynamics approach that features a detailed micro-physical model of the interaction of spherical grains. For the first time, the model has been extended by introducing a new visco-elastic damping force which requires a proper calibration. Afterwards, different sample generation methods were used to cover a wide range of aggregate types. Results: The visco-elastic damping force introduced in this work turns out to be crucial to reproduce results obtained from laboratory experiments. After proper calibration, we find that erosion occurs for impact velocities of 5 m/s and above. Though fractal aggregates as ...

  12. Dune erosion above revetments

    NARCIS (Netherlands)

    Van Thiel de Vries, J.S.M.

    2012-01-01

    In a situation with a narrow dune, the dune base can be protected with a revetment to reduce dune erosion during extreme events. To quantify the effects of a revetment on storm impact, the functionality of the numerical storm impact model XBeach (Roelvink et al., 2009) is extended to account for the

  13. Calibrating thermal erosion models along an Arctic coastline

    Science.gov (United States)

    Wobus, C. W.; Anderson, R. S.; Overeem, I.; Urban, F. E.; Clow, G. D.; Stanton, T. P.

    2009-12-01

    Coastal erosion rates of 20-30 meters per year have been documented along Alaska’s Beaufort Sea coastline, and a number of studies suggest that erosion rates have accelerated as a result of climate change. However, a lack of direct observational evidence has limited our progress in quantifying the role of climate change on coastal erosion rates in the Arctic. In particular, while longer ice-free periods are likely to lead to both warmer surface waters and longer fetch, the relative roles of thermal and mechanical (wave) erosion in driving coastal retreat have not been comprehensively quantified. We focus on the potential magnitude of thermal erosion along a permafrost coastline in the northern National Petroleum Reserve-Alaska (NPR-A), where erosion rates have averaged 10-15 meters/year over two years of direct monitoring. We take advantage of these extraordinary rates of coastal erosion to directly observe erosion processes via time-lapse photography, while monitoring temperature, solar radiation and wind speed at the same time. These combined observations are used to calibrate models of thermal erosion. Our observations suggest that virtually all of the erosion in this setting can be explained as a purely thermal process. Coastal bluffs are first notched and then topple into the ocean, failing dominantly along ice wedges that serve as planes of weakness. Furthermore, the high ice content and the fine grain size of the coastal plain materials that comprise the bluffs appear to limit any strong negative feedback on erosion rates, since the sediments are readily dispersed on the shallow shelf. Although erosion driven purely by thermal processes may be unique to this particular coastal zone, these observations implicate a direct relationship between climatic warming and landscape change. Erosion of sandy coastlines in other parts of the NPR-A may also be ultimately controlled by thermal energy, once a thin veneer of clastic material is removed by wave action from

  14. Part 2: Adaptation of Gait Kinematics in Unilateral Cerebral Palsy Demonstrates Preserved Independent Neural Control of Each Limb

    Science.gov (United States)

    Bulea, Thomas C.; Stanley, Christopher J.; Damiano, Diane L.

    2017-01-01

    Motor adaptation, or alteration of neural control in response to a perturbation, is a potential mechanism to facilitate motor learning for rehabilitation. Central nervous system deficits are known to affect locomotor adaptation; yet we demonstrated that similar to adults following stroke, children with unilateral brain injuries can adapt step length in response to unilateral leg weighting. Here, we extend our analysis to explore kinematic strategies underlying step length adaptation and utilize dynamical systems approaches to elucidate how neural control may differ in those with hemiplegic CP across legs and compared to typically developing controls. Ten participants with hemiplegic CP and ten age-matched controls participated in this study. Knee and hip joint kinematics were analyzed during unilateral weighting of each leg in treadmill walking to assess adaptation and presence and persistence of after-effects. Peak joint angle displacement was used to represent changes in joint angles during walking. We examined baseline and task-specific variability and local dynamic stability to evaluate neuromuscular control across groups and legs. In contrast to controls, children with unilateral CP had asymmetries in joint angle variability and local dynamic stability at baseline, showing increased variability and reduced stability in the dominant limb. Kinematic variability increased and local stability decreased during weighting of ipsilateral and contralateral limbs in both groups compared to baseline. After weight removal both measures returned to baseline. Analogous to the temporal-spatial results, children with unilateral CP demonstrated similar capability as controls to adapt kinematics to unilateral leg weighting, however, the group with CP differed across sides after weight removal with dominant limb after-effects fading more quickly than in controls. The change in kinematics did not completely return to baseline in the non-dominant limb of the CP group, producing a

  15. Severe Environmental Corrosion Erosion Facility

    Data.gov (United States)

    Federal Laboratory Consortium — NETL’s Severe Environment Corrosion Erosion Facility in Albany, OR, allows researchers to safely examine the performance of materials in highly corrosive or erosive...

  16. Evaluation of the Serum Zinc Level in Erosive and Non-Erosive Oral Lichen Planus

    Directory of Open Access Journals (Sweden)

    Gholizadeh N.

    2013-10-01

    Full Text Available Statement of Problem: Lichen planus is a chronic inflammatory immunologic-based disease involving skin and mucosa. This disease is generally divided into two categories: erosive and non-erosive. Many etiologic factors are deliberated regarding the disease; however, the disorders of immune system and the role of cytotoxic T-lymphocytes and monocytes are more highlighted. Zinc is an imperative element for the growth of epithelium and its deficiency induces the cytotoxic activity of T-helper2 cells which seems to be associated with lichen planus. Purpose: This study aimed to evaluate the levels of serum zinc in erosive and non-erosive oral lichen planus (OLP and compares it with the healthy control group to find out any feasible inference. Materials and Method: A total of 22 patients with erosive oral lichen planus, 22 pa-tients with non erosive OLP and 44 healthy individuals as the control group were recruited in this descriptive-comparative study. All the participants were selected from the referees to the department of oral medicine, school of dentistry, Tabriz University of medical sciences. Serum zinc level was examined for all the individuals with liquid-stat kit (Beckman Instruments Inc., Carlsbad, CA. Data were analyzed by adopting the ANOVA and Tukey tests through SPSS 16 statistical software. Results: The mean age of patients with erosive and non-erosive LP was 41.7 and 41.3 years, respectively. The mean age of the healthy control group was 34.4 years .The mean serum zinc levels in the erosive and non erosive lichen planus groups and control groups were 8.3 (1.15, 11.15 (0.92 and 15.74 (1.75 μg/dl respectively. The difference was statistically significant (p< 0.05. Conclusion: The serum zinc levels were decreased in patients with erosive oral lichen planus. This finding may probably indicate the promising role of zinc in development of oral lichen planus.

  17. Online operations optimization of waste incineration plants. Phase 3: Control concept and demonstration; Online driftsoptimering af affaldsfyrede anlaeg. Fase 3: Reguleringskoncept og demonstration. Hovedrapport ver. C

    Energy Technology Data Exchange (ETDEWEB)

    Boecher Poulsen, K.; Rassing Stoltze, K.; Solberg, B.; Hansen, Lars Henrik (DONG Energy (Denmark)); Cramer, J.; Andreasen, L.B. (FORCE Technology (Denmark)); Nymann Thomsen, S.; West, F. (Babcock and Wilcox Voelund (Denmark)); Clausen, S.; Fateev, A. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark))

    2010-06-15

    The long-term vision of the project is to develop a system for online optimisation of waste incineration. The fundamental idea is to base the system on advanced measuring technique, dynamic process models and advanced control technique. In the present phase 3 project the intention is to implement several of the improvement measures specified in phase 2 - both at Haderslev CHP Plant and at Reno-Nord - and not least evaluate the results from the two widely different plants. In addition to that, it is essential to test the new NIR camera system online at Reno-Nord and to carry out a complete measuring campaign where dynamic characteristics are pursued and must be compared with similar tests from phase 2 at Haderslev CHP Plant. The measuring campaign at Reno-Nord was performed differently from phase 2 at Haderslev CHP Plant, i.e. at Reno-Nord both traditional manual steps in series with input (pusher, grate, primary air) and manual control and pseudo random parallel pulse effects of all input with partly automatic control were performed. Pulse effects are made automatically from a sequence in the control room. The new method requires considerably less involvement from operating staff and engineers during the tests, and it is capable of producing good model estimation data as the control will automatically lead the incineration back to the fixed incineration point. The disadvantage is that it is difficult to follow the quality of the boiler responses in the process because of several concurrent step effects. Therefore, another data processing is necessary to be able to estimate the correct dynamic models and extract dynamic furnace characteristics. However, the potential of the new method is that it can be activated directly by the operating staff from the control room and that it is capable of operating for a long time with eg considerably different fuel types. As to modelling, both SISO (single input single output) and MIMO (multi input multi output) model estimates

  18. [Effect of dexamethasone on indomethacin-induced gastric erosion formation upon duration of the hormonal action].

    Science.gov (United States)

    Podvigina, T T; Morozova, O Iu; Bagaeva, T R; Filaretova, L P

    2009-07-01

    The aim of the study was to verify a dependence of dexamethasone effect on the gastric erosion formation upon duration of the hormonal action. Gastric erosions were induced by indometha cin (35 mg/kg, sc) in male rats after 24-hour fasting. The rats were given a single injection of dexamethasone at a dose of 1 mg/kg and they underwent the ulcerogenic stimulus (indomethacin) at va rious time points after the hormonal injection (1, 6, 12, 18, 24 hours as well as 3, 5, 7 days). The control rats were given dexamethasone vehicle. In 4 hours after indomethacin injection gastric erosions, corticosterone and blood glucose levels, as well as body and thymus weights were examined. The results obtained demonstrate a dependence ofdexamethasone effect on the gastric erosion formation upon duration of its action: dexamethasone attenuated or aggravated indomethacin-induced gastric erosions depending on the time of its injection. Gastroprotective action of dexamethasone was observed in the case of its injection 1, 6, and 12 hours before indomethacin. The further increase in the time interval caused transformation of gastroprotective action of dexamethasone against ulcerogenic effect. The data obtained suggest that a disturbance of carbohydrate regulation accompanied with the signs of catabolic effects of the glucocorticoid may be responsible for the ulcerogenic action of dexamethasone.

  19. The development and demonstration of hybrid programmable attitude control electronics. [with adaptable analog/digital design approach

    Science.gov (United States)

    Smith, L. S.; Kopf, E. H., Jr.

    1974-01-01

    HYPACE provides an adaptable, analog/digital design approach that permits preflight and in-flight accommodation of mission changes, component performance variations, spacecraft changes, etc., through programing. This enabled broad multimission flexibility of application in a cost-effective manner. The HYPACE design, which was demonstrated in breadboard form on a single-axis gas-bearing spacecraft simulation, uses a single control channel to perform the attitude control functions sequentially, thus significantly reducing the number of component parts over hard-wired designs. The success of this effort resulted in the concept being selected for the Mariner/Jupiter/Saturn 1977 spacecraft application.

  20. The development and demonstration of hybrid programmable attitude control electronics. [with adaptable analog/digital design approach

    Science.gov (United States)

    Smith, L. S.; Kopf, E. H., Jr.

    1974-01-01

    HYPACE provides an adaptable, analog/digital design approach that permits preflight and in-flight accommodation of mission changes, component performance variations, spacecraft changes, etc., through programing. This enabled broad multimission flexibility of application in a cost-effective manner. The HYPACE design, which was demonstrated in breadboard form on a single-axis gas-bearing spacecraft simulation, uses a single control channel to perform the attitude control functions sequentially, thus significantly reducing the number of component parts over hard-wired designs. The success of this effort resulted in the concept being selected for the Mariner/Jupiter/Saturn 1977 spacecraft application.

  1. Online operations optimization of waste incineration plants. Phase 3: Control concept and demonstration; Online driftsoptimering af affaldsfyrede anlaeg. Fase 3: Reguleringskoncept og demonstration. Hovedrapport ver. C

    Energy Technology Data Exchange (ETDEWEB)

    Boecher Poulsen, K.; Rassing Stoltze, K.; Solberg, B.; Hansen, Lars Henrik (DONG Energy (Denmark)); Cramer, J.; Andreasen, L.B. (FORCE Technology (Denmark)); Nymann Thomsen, S.; West, F. (Babcock and Wilcox Voelund (Denmark)); Clausen, S.; Fateev, A. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark))

    2010-06-15

    The long-term vision of the project is to develop a system for online optimisation of waste incineration. The fundamental idea is to base the system on advanced measuring technique, dynamic process models and advanced control technique. In the present phase 3 project the intention is to implement several of the improvement measures specified in phase 2 - both at Haderslev CHP Plant and at Reno-Nord - and not least evaluate the results from the two widely different plants. In addition to that, it is essential to test the new NIR camera system online at Reno-Nord and to carry out a complete measuring campaign where dynamic characteristics are pursued and must be compared with similar tests from phase 2 at Haderslev CHP Plant. The measuring campaign at Reno-Nord was performed differently from phase 2 at Haderslev CHP Plant, i.e. at Reno-Nord both traditional manual steps in series with input (pusher, grate, primary air) and manual control and pseudo random parallel pulse effects of all input with partly automatic control were performed. Pulse effects are made automatically from a sequence in the control room. The new method requires considerably less involvement from operating staff and engineers during the tests, and it is capable of producing good model estimation data as the control will automatically lead the incineration back to the fixed incineration point. The disadvantage is that it is difficult to follow the quality of the boiler responses in the process because of several concurrent step effects. Therefore, another data processing is necessary to be able to estimate the correct dynamic models and extract dynamic furnace characteristics. However, the potential of the new method is that it can be activated directly by the operating staff from the control room and that it is capable of operating for a long time with eg considerably different fuel types. As to modelling, both SISO (single input single output) and MIMO (multi input multi output) model estimates

  2. Soil erosion in China based on the 2000 national remote sensing survey

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper discussed the spatial distribution of soil erosion in China at the end of the 20thcentury based on the second national soil erosion survey. The result indicated soil erosion is still theprime environmental problem in China. Soil erosion mainly occurs in the western regions of China,and the slight erosion type, ion the whole, exerts the greatest impact on soil erosion pattern. Thedistribution of water erosion shows the impact of landforms: slight water erosion mainly inmountainous and hilly areas, and half of violent water erosion on the loess landforms. Farmland,forestland and grassland are the major land use types of slight hydraulic erosion distribution, while theserious hydraulic erosion and slight wind erosion mainly occur on grassland. Thus, the conservation ofthe grassland is the key to either hydraulic and wind erosion control. The huangmian soil (a major typeof cultivated soil developed from loess mother material) is the one facing the most serious threat fromsoil erosion in Chinas soil resources. Further discussion on the soil erosion distribution still needs moreresearch on the method and relevant data analysis.

  3. Bioengineering applied to erosion and stability control in the North Apennines (Emilia-Romagna Region, Italy): a check about critical aspects of the works.

    Science.gov (United States)

    Selli, Lavinia; Cavazza, Claudio; Pavanelli, Donatella

    2013-04-01

    Because of its geological structure, in the Emilia-Romagna Region over 32,000 landslides have been identified. Several works have been made in order to control mass movement's dynamics and to secure of Reno and Lamone Mountain Basin Rivers, the road network and near by villages and towns. Most of the control works dealt with bioengineering practices: palisades piles, geotextiles, seedings, surface flow control works, dikes within main drainage ditches. In order to check about critical aspects related to the use of these techniques in the Apennines, a survey in this basins was designed with specific interest in the several kinds of works realised, in which plant species were mostly used and in the factors that affected the success or failure of the works. Territory encompasses steep slopes covered with woods to low reliefs covered with grasslands. It is characterized by prevailing clays, inducing instability, and arenaceous lithology with impermeable soils; drainage density is quite high and hillsides suffer extensive and severe erosion and slope stability problems. Chestnut woods mainly represent land use at higher altitudes, while coppice, pastures and crops are present on milder hillsides. The remaining part of the basin is covered by vineyards, orchards, ponds and urban areas, which are basically located in the valley floor. Precipitation events mainly consist of rainfall ranging between 950-1015 mm per year; few snowfalls occur during winter and a long dry season lasts from June until September. We have analyzed 187 works designed mainly for the consolidation of slope instabilities through a widespread enhancement of the vegetation cover. The surveyed works are classified as a function of their building features: it can be seen that cribwalls and palisades are by far the most common types, being the 24% and the 34% respectively of the works. As far as the most adopted plant species, they were silver willow (Salix alba), Spanish Broom (Spartium Junceum) and

  4. Demonstration of Active Power Controls by Utility-Scale PV Power Plant in an Island Grid: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Gevorgian, Vahan; O' Neill, Barbara

    2017-02-01

    The National Renewable Energy Laboratory (NREL), AES, and the Puerto Rico Electric Power Authority conducted a demonstration project on a utility-scale photovoltaic (PV) plant to test the viability of providing important ancillary services from this facility. As solar generation increases globally, there is a need for innovation and increased operational flexibility. A typical PV power plant consists of multiple power electronic inverters and can contribute to grid stability and reliability through sophisticated 'grid-friendly' controls. In this way, it may mitigate the impact of its variability on the grid and contribute to important system requirements more like traditional generators. In 2015, testing was completed on a 20-MW AES plant in Puerto Rico, and a large amount of test data was produced and analyzed that demonstrates the ability of PV power plants to provide various types of new grid-friendly controls. This data showed how active power controls can leverage PV's value from being simply an intermittent energy resource to providing additional ancillary services for an isolated island grid. Specifically, the tests conducted included PV plant participation in automatic generation control, provision of droop response, and fast frequency response.

  5. Experimental demonstration of using divergence cost-function in SPGD algorithm for coherent beam combining with tip/tilt control.

    Science.gov (United States)

    Geng, Chao; Luo, Wen; Tan, Yi; Liu, Hongmei; Mu, Jinbo; Li, Xinyang

    2013-10-21

    A novel approach of tip/tilt control by using divergence cost function in stochastic parallel gradient descent (SPGD) algorithm for coherent beam combining (CBC) is proposed and demonstrated experimentally in a seven-channel 2-W fiber amplifier array with both phase-locking and tip/tilt control, for the first time to our best knowledge. Compared with the conventional power-in-the-bucket (PIB) cost function for SPGD optimization, the tip/tilt control using divergence cost function ensures wider correction range, automatic switching control of program, and freedom of camera's intensity-saturation. Homemade piezoelectric-ring phase-modulator (PZT PM) and adaptive fiber-optics collimator (AFOC) are developed to correct piston- and tip/tilt-type aberrations, respectively. The PIB cost function is employed for phase-locking via maximization of SPGD optimization, while the divergence cost function is used for tip/tilt control via minimization. An average of 432-μrad of divergence metrics in open loop has decreased to 89-μrad when tip/tilt control implemented. In CBC, the power in the full width at half maximum (FWHM) of the main lobe increases by 32 times, and the phase residual error is less than λ/15.

  6. The effect of enamel proteins on erosion

    Science.gov (United States)

    Baumann, T.; Carvalho, T. S.; Lussi, A.

    2015-01-01

    Enamel proteins form a scaffold for growing hydroxyapatite crystals during enamel formation. They are then almost completely degraded during enamel maturation, resulting in a protein content of only 1% (w/v) in mature enamel. Nevertheless, this small amount of remaining proteins has important effects on the mechanical and structural properties of enamel and on the electrostatic properties of its surface. To analyze how enamel proteins affect tooth erosion, human enamel specimens were deproteinated. Surface microhardness (SMH), surface reflection intensity (SRI) and calcium release of both deproteinated and control specimens were monitored while continuously eroding them. The deproteination itself already reduced the initial SMH and SRI of the enamel significantly (p erosion, the progression of all three evaluated parameters differed significantly between the two groups (p erosion, where not only surface softening but surface loss can be observed. We conclude that enamel proteins have a significant effect on erosion, protecting the enamel and slowing down the progression of erosion when irreversible surface loss starts to occur. PMID:26468660

  7. Vaporization of atherosclerotic plaques by spark erosion

    NARCIS (Netherlands)

    C.J. Slager (Cornelis); C.E. Essed; J.C.H. Schuurbiers (Johan); N. Bom (Klaas); P.W.J.C. Serruys (Patrick); G.T. Meester (Geert)

    1985-01-01

    textabstractAn alternative to the laser irradiation of atherosclerotic lesions has been developed. A pulsed electrocardiogram R wave-triggered electrical spark erosion technique is described. Controlled vaporization of fibrous and lipid plaques with minimal thermal side effects was achieved and docu

  8. Rheumatoid arthritis bone erosion volumes on CT and MRI: reliability and correlations with erosion scores on CT, MRI and radiography

    DEFF Research Database (Denmark)

    Møller Døhn, Uffe; Ejbjerg, Bo J; Hasselquist, Maria;

    2007-01-01

    controls underwent unilateral CT, MRI and radiography of second to fifth MCP joints in one hand. Erosion volumes (using OSIRIS software) and scores were determined from CT, MRI and radiography (scores only). RESULTS: CT, MRI and radiography detected 77, 62 and 12 erosions, respectively. On CT, the mean...

  9. Particle erosion of infrared materials

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Erosion test of some infrared (IR) optical crystals (Ge,ZnS,MgF2,and quartz) was conducted with a number of different erodents (glass bead,and angular SiC,SiO2,Al2O3 by a homemade gas-blasting erosion tester.The influence of impact angle,impact velocity,erodent,and erosion time on the erosion rate and the effect of erosion on their IR transmittance were studied.The damaged surface morphology was characterized by scanning electron microscopy,and the erosion mechanism was explored.All of the materials show the maximum in wear versus impact angle at 90°,confirming their brittle failure behavior.It is found that the erosion rate is dependent on the erodent velocity by a power law,and it is highly correlated to the hardness of the erodent.The erosion rate-time curves do not show an incubation state,but an accelerated erosion period followed a maximum erosion (steady state).The decrease of IR transmittance is direct proportion to the erosion rate.Although the material loss occurs primarily by brittle process,ductile behavior is clearly an important feature,especially for MgF2 and ZnS.

  10. Actinides, accelerators and erosion

    Science.gov (United States)

    Tims, S. G.; Fifield, L. K.

    2012-10-01

    Fallout isotopes can be used as artificial tracers of soil erosion and sediment accumulation. The most commonly used isotope to date has been 137Cs. Concentrations of 137Cs are, however, significantly lower in the Southern Hemisphere, and furthermore have now declined to 35% of original values due to radioactive decay. As a consequence the future utility of 137Cs is limited in Australia, with many erosion applications becoming untenable within the next 20 years, and there is a need to replace it with another tracer. Plutonium could fill this role, and has the advantages that there were six times as many atoms of Pu as of 137Cs in fallout, and any loss to decay has been negligible due to the long half-lives of the plutonium isotopes. Uranium-236 is another long-lived fallout isotope with significant potential for exploitation as a tracer of soil and sediment movement. Uranium is expected to be more mobile in soils than plutonium (or caesium), and hence the 236U/Pu ratio will vary with soil depth, and so could provide an independent measure of the amount of soil loss. In this paper we discuss accelerator based ultra-sensitive measurements of plutonium and 236U isotopes and their advantages over 137Cs as tracers of soil erosion and sediment movement.

  11. Actinides, accelerators and erosion

    Directory of Open Access Journals (Sweden)

    Fifield L.K.

    2012-10-01

    Full Text Available Fallout isotopes can be used as artificial tracers of soil erosion and sediment accumulation. The most commonly used isotope to date has been 137Cs. Concentrations of 137Cs are, however, significantly lower in the Southern Hemisphere, and furthermore have now declined to 35% of original values due to radioactive decay. As a consequence the future utility of 137Cs is limited in Australia, with many erosion applications becoming untenable within the next 20 years, and there is a need to replace it with another tracer. Plutonium could fill this role, and has the advantages that there were six times as many atoms of Pu as of 137Cs in fallout, and any loss to decay has been negligible due to the long half-lives of the plutonium isotopes. Uranium-236 is another long-lived fallout isotope with significant potential for exploitation as a tracer of soil and sediment movement. Uranium is expected to be more mobile in soils than plutonium (or caesium, and hence the 236U/Pu ratio will vary with soil depth, and so could provide an independent measure of the amount of soil loss. In this paper we discuss accelerator based ultra-sensitive measurements of plutonium and 236U isotopes and their advantages over 137Cs as tracers of soil erosion and sediment movement.

  12. Control System Design Implementation and Preliminary Demonstration for a Tendon-Actuated Lightweight In-Space MANipulator (TALISMAN)

    Science.gov (United States)

    Komendera, Erik E.; Doggett, William R.; Dorsey, John T.; Debus, Thomas J.; Holub, Kris; Dougherty, Sean P.

    2015-01-01

    Satellite servicing is a high priority task for NASA and the space industry, addressing the needs of a variety of missions, and potentially lowering the overall cost of missions through refurbishment and reuse. However, the ability to service satellites is severely limited by the lack of long reach manipulation capability and inability to launch new devices due the end of the Space Transport System, or Space Shuttle Program. This paper describes the design and implementation of a control system for a Tendon-Actuated Lightweight In-Space MANipulator (TALISMAN), including; defining the forward and inverse kinematics, endpoint velocity to motor velocity, required cable tensions, and a proportional-integral-derivative (PID) controller. The tensions and velocities necessary to maneuver and capture small and large payloads are also discussed. To demonstrate the utility of the TALISMAN for satellite servicing, this paper also describes a satellite servicing demonstration using two TALISMAN prototypes to grasp and inspect a satellite mockup. Potential avenues for improving the control system are discussed.

  13. Crash response data system for the controlled impact demonstration (CID) of a full-scale transport aircraft

    Science.gov (United States)

    Calloway, R. S.; Knight, V. H., Jr.

    1986-01-01

    A study involving the Controlled Impact Demonstration (CID) of a transport category aircraft was conducted with the objective to improve occupant safety during survivable crash scenarios. in connection with this study, the first remotely-piloted Full-Scale Transport aircraft was purposely crashed into the California desert. The program was initated to demonstrate the effectiveness of an imisting kerosene (AMK), a fuel additive emplyed to reduce postcrash fires. The unmanned CID flight carried 73 life-like flight research dummies, multiple experiments, high-speed interior cabin cameras, and the high-environment Crash Response Data System. Attention is given to the design approach, a block diagram of the Crash Response Data System, measurements, the digital data subsystem, signal conditioning, telemetry, on-board recording, the power subsystem, preflight checkout and calibration, and aspects of system qualification.

  14. Demonstration of Bias-Controlled Algorithmic Tuning of Quantum Dots in a Well (DWELL) MidIR Detectors

    Science.gov (United States)

    2009-06-01

    In the 0018-9197/$25.00 © 2009 IEEE Authorized licensed use limited to: UNIVERSITY OF NEW MEXICO. Downloaded on June 5, 2009 at 23:33 from IEEE Xplore . Restrictions...limited to: UNIVERSITY OF NEW MEXICO. Downloaded on June 5, 2009 at 23:33 from IEEE Xplore . Restrictions apply. 676 IEEE JOURNAL OF QUANTUM...June 5, 2009 at 23:33 from IEEE Xplore . Restrictions apply. JANG et al.: DEMONSTRATION OF BIAS-CONTROLLED ALGORITHMIC TUNING OF DWELL MIDINFRARED

  15. Conception de couches minces tribologiques pour augmenter la resistance a l'erosion par impacts de particules

    Science.gov (United States)

    Hassani, Salim

    calculation variables include impact velocity (in the range of 50--300 m/s), particle size and the mechanical properties of both the target and the impacting particle. Specifically, we investigate the impact response of coatings fabricated by physical vapor deposition (PVD) and plasma enhanced chemical vapor deposition (PECVD). This includes single and multilayer TiN and nanocomposite nc-TiN/a-SiN1.3 and nc-TiCN/a-SiCN systems on titanium alloy and stainless steel substrates. In particular, we correlate the thickness and the coating macroscopic properties, such as hardness, Young's modulus, and toughness with the erosion. The calculations confirmed earlier findings that for a single layer coating, a combination of low modulus and a high thickness lead to local stress reduction and hence possible erosion resistance enhancement. The FE simulations have further shown that a tensile stress exceeding a critical stress sigmacrit = 3.95 GPa can be easily produced by a single particle impact. For each combination of particle velocity and size, a map of tensile stresses in the TiN coating, corresponding to the predicted erosion performance, was produced. The FE model has then been extended to multilayer coating systems containing superhard nanocomposite materials. These coatings configurations, when combined with tailored mechanical properties have shown to provide an improvement of the performance over comparable single layer configurations. The development of high performance erosion-resistant coatings also requires understanding of stress propagation upon particle impact. In the second part of this work, we apply a finite element methodology to enhance and optimize the resistance of protective coatings to erosion by solid particles with appropriate stress management. A controlled distribution of the initial residual stress in the coating was used to counteract impact stress, while a Young's modulus distribution was applied to optimize impact energy spreading throughout the coating

  16. Demonstrating coherent control in 85Rb2 using ultrafast laser pulses: a theoretical outline of two experiments

    CERN Document Server

    Martay, Hugo E L; England, Duncan G; Friedman, Melissa E; Petrovic, Jovana; Walmsley, Ian A

    2009-01-01

    Calculations relating to two experiments that demonstrate coherent control of preformed rubidium-85 molecules in a magneto-optical trap using ultrafast laser pulses are presented. In the first experiment, it is shown that pre-associated molecules in an incoherent mixture of states can be made to oscillate coherently using a single ultrafast pulse. A novel mechanism that can transfer molecular population to more deeply bound vibrational levels is used in the second. Optimal parameters of the control pulse are presented for the application of the mechanism to molecules in a magneto-optical trap. The calculations make use of an experimental determination of the initial state of molecules photoassociated by the trapping lasers in the magneto-optical trap and use shaped pulses consistent with a standard ultrafast laser system.

  17. Device Demonstration

    Science.gov (United States)

    2006-12-31

    RPM, HMDS ( notched ) CAP 112 Resist erosion test resist removal xx = 20 1/26/06 100 Etch (2/23/06) 60 sec; Thicker PR; did 3.3 cP, 1K RPM, HMDS new 3...laser beam deflects. This is a simple system, but may not provide the detailed information that initially is needed. 2. Use a Michelson interferometer...deflection of membrane windows in bulge tester. 3. Use a Shearing interferometer. This technique has the potential for being simpler than a Michelson

  18. Evolving Landscapes: the Effect of Genetic Variation on Salt Marsh Erosion

    Science.gov (United States)

    Bernik, B. M.; Blum, M. J.

    2014-12-01

    Ecogeomorphic studies have demonstrated that biota can exert influence over geomorphic processes, such as sediment transport, which in turn have biotic consequences and generate complex feedbacks. However, little attention has been paid to the potential for feedback to arise from evolutionary processes as population genetic composition changes in response to changing physical landscapes. In coastal ecosystems experiencing land loss, for example, shoreline erosion entails reduced plant survival and reproduction, and thereby represents a geomorphic response with inherent consequences for evolutionary fitness. To get at this topic, we examined the effect of genetic variation in the saltmarsh grass Spartina alterniflora, a renowned ecosystem engineer, on rates of shoreline erosion. Field transplantation studies and controlled greenhouse experiments were conducted to compare different genotypes from both wild and cultivated populations. Plant traits, soil properties, accretion/subsidence, and rates of land loss were measured. We found significant differences in rates of erosion between field plots occupied by different genotypes. Differences in erosion corresponded to variation in soil properties including critical shear stress and subsidence. Plant traits that differed across genotypes included belowground biomass, root tensile strength, and C:N ratios. Our results demonstrate the importance of genetic variation to salt marsh functioning, elucidating the relationship between evolutionary processes and ecogeomorphic dynamics in these systems. Because evolutionary processes can occur on ecological timescales, the direction and strength of ecogeomorphic feedbacks may be more dynamic than previously accounted for.

  19. Landform design conditions Runoff and erosion control on reclaimed areas; Diseno de la Morfologia y Red de Drenaje en la Restaurationes Mineras

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    Landform construction in Utrillas coal field, where the MFUSA Company is operating, is based on the runoff sharing out, making up different hydrological catchment. Artificial slopes, flat platforms, and the dram age network, with channels and small ponds, compose reclaimed cathments, which are connected to the natural drainage network. The goal of the project is to set up some tools for Landform design, i. e. hydrological and erosion models. The models give a quantitative base for predicting the long-term stability of reclaimed catchments. Empirical values of the parameters have been obtained by measuring runoff and sediments rates at the slope and catchments level. Runoff is predicted by applying the Curve Number Method. RUSLE 1.06, Rusle for Mined Lands, Construction Sites and Reclaimed Lands, is applied for soil erosion prediction at slope scale and MUSLE at catchment scale. It is explained the methodology for applying these models in others coal fields. Finally rules for conservation and management of the reclaimed catchments are given, emphasizing the influence of the Mediterranean-Continental climate. (Author)

  20. Field studies of beach cones as coastal erosion control/reversal devices for areas with significant oil and gas activities. [Annual report], February 24, 1992--February 23, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Law, V.J.

    1993-03-15

    The primary objective of this project is to evaluate the utility of a device called the ``beach cone`` in combating coastal erosion. Seven initial sites were selected for testing beach cones in a variety of geometric configurations. Permits were obtained from the State of Louisiana and the US Army Corps of Engineers to perform the work associated with this study. Six hundred beach cones were actually installed at six of the sites in late July and early August, 1992. One of the initial sites was abandoned because it was found to be unsuitable for beach cone placement. The test sites have been observed for six months and preliminary findings indicate that beach cones accreted significant amounts of materials along the beach of a barrier island. At other test sites, accretion rates have been less dramatic but importantly, no significant additional erosion has occurred, which is a positive result. It is too soon to state the categorical success of the beach cones, but results to date are encouraging.

  1. Bluetooth wireless monitoring, diagnosis and calibration interface for control system of fuel cell bus in Olympic demonstration

    Science.gov (United States)

    Hua, Jianfeng; Lin, Xinfan; Xu, Liangfei; Li, Jianqiu; Ouyang, Minggao

    With the worldwide deterioration of the natural environment and the fossil fuel crisis, the possible commercialization of fuel cell vehicles has become a hot topic. In July 2008, Beijing started a clean public transportation plan for the 29th Olympic games. Three fuel cell city buses and 497 other low-emission vehicles are now serving the Olympic core area and Beijing urban areas. The fuel cell buses will operate along a fixed bus line for 1 year as a public demonstration of green energy vehicles. Due to the specialized nature of fuel cell engines and electrified power-train systems, measurement, monitoring and calibration devices are indispensable. Based on the latest Bluetooth wireless technology, a novel Bluetooth universal data interface was developed for the control system of the fuel cell city bus. On this platform, a series of wireless portable control auxiliary systems have been implemented, including wireless calibration, a monitoring system and an in-system programming platform, all of which are ensuring normal operation of the fuel cell buses used in the demonstration.

  2. A terminological matter: paragenesis, antigravitative erosion or antigravitational erosion ?

    Directory of Open Access Journals (Sweden)

    Pasini G.

    2009-07-01

    Full Text Available In the speleological literature three terms are utilized to designate the “ascending erosion”: paragenesis (= paragénésis, coined in1968, antigravitative erosion (= erosione antigravitativa, coined in 1966 and antigravitational erosion (wrong English translation ofthe Italian term erosione antigravitativa, utilized later on. The term paragenesis should be abandoned because of the priority of theterm erosione antigravitativa - on the ground of the “law of priority” – and because of its ambiguous etimology. On the other hand,the term antigravitational erosion should be forsaken in favour of the term antigravitative erosion, given the meaning that the termsgravitation and gravity have in Physics. Therefore, to designate the phenomenon of the “ascending erosion” there would be nothingleft but the term antigravitative erosion.The antigravitative erosion process and its recognizability are illustrated.Examples of caves with evident antigravitative erosion phenomena, developed in different karstifiable rocks and in several partsof the world, are given.It is recalled that the antigravitative erosion is a phenomenon well-known since 1942 and widely proven and supported, and that it isrelatively easy – in many cases - to recognize the antigravitative origin of karstic passages.It is stressed that the antigravitative erosion is an important phenomenon, exclusive of the karstic caves and unique in nature.

  3. Soil Erosion: Advanced Crop and Soil Science. A Course of Study.

    Science.gov (United States)

    Miller, Larry E.

    The course of study represents the last of six modules in advanced crop and soil science and introduces the agriculture student to the topic of soil erosion. Upon completion of the two day lesson, the student will be able to: (1) define conservation, (2) understand how erosion takes place, and (3) list ways of controlling wind and water erosion.…

  4. A hierachical method for soil erosion assessment and spatial risk modelling

    NARCIS (Netherlands)

    Okoth, P.F.

    2003-01-01

      Though a lot has been done and achieved in erosion research and control in Kenya, most of the erosion research methods have in the past put emphasis more on quantifying soil loss or measuring soil erosion, rather than pinpointing to

  5. A hierachical method for soil erosion assessment and spatial risk modelling

    NARCIS (Netherlands)

    Okoth, P.F.

    2003-01-01

      Though a lot has been done and achieved in erosion research and control in Kenya, most of the erosion research methods have in the past put emphasis more on quantifying soil loss or measuring soil erosion, rather than pinpointing to area

  6. Synthesising empirical results to improve predictions of post-wildfire runoff and erosion response

    Science.gov (United States)

    Shakesby, Richard A.; Moody, John A.; Martin, Deborah A.; Robichaud, Peter R.

    2016-01-01

    Advances in research into wildfire impacts on runoff and erosion have demonstrated increasing complexity of controlling factors and responses, which, combined with changing fire frequency, present challenges for modellers. We convened a conference attended by experts and practitioners in post-wildfire impacts, meteorology and related research, including modelling, to focus on priority research issues. The aim was to improve our understanding of controls and responses and the predictive capabilities of models. This conference led to the eight selected papers in this special issue. They address aspects of the distinctiveness in the controls and responses among wildfire regions, spatiotemporal rainfall variability, infiltration, runoff connectivity, debris flow formation and modelling applications. Here we summarise key findings from these papers and evaluate their contribution to improving understanding and prediction of post-wildfire runoff and erosion under changes in climate, human intervention and population pressure on wildfire-prone areas.

  7. How does slope form affect erosion in CATFLOW-SED?

    Science.gov (United States)

    Gabelmann, Petra; Wienhöfer, Jan; Zehe, Erwin

    2016-04-01

    Erosion is a severe environmental problem in agro-ecosystems with highly erodible loess soils. It is controlled by various factors, e.g. rainfall intensity, initial wetness conditions, soil type, land use and tillage practice. Furthermore slope form and gradient have been shown to influence erosion amounts to a large extent. Within the last fifty years, various erosion models have been developed to describe the erosion process, estimate erosion amounts and identify erosion-prone areas. These models differ in terms of complexity, the processes which are considered, and the data required for model calibration and they can be categorised into empirical or statistical, conceptual, and physically-based models. CATFLOW-SED is a process-based hydrology and erosion model that can operate on catchment and hillslope scales. Soil water dynamics are described by the Richards equation including effective approaches for preferential flow. Evapotranspiration is simulated using an approach based on the Penman-Monteith equation. The model simulates overland flow using the diffusion wave equation. Soil detachment is related to the attacking forces of rainfall and overland flow, and the erosion resistance of soil. Sediment transport capacity and sediment deposition are related to overland flow velocity using the equation of Engelund and Hansen and the sinking velocity of grain sizes respectively. We performed a study to analyse the erosion process on different virtual hillslopes, with varying slope gradient and slope form, using the CATFLOW-SED model. We explored the role of landform on erosion and sedimentation, particularly we look for forms that either maximise or minimise erosion. Results indicate the importance to performing the process implementation within physically meaningful limits and choose appropriate model parameters respectively.

  8. German Contribution to the X-38 CRV Demonstrator in the Field of Guidance, Navigation and Control (GNC)

    Science.gov (United States)

    Soppa, Uwe; Görlach, Thomas; Roenneke, Axel Justus

    2002-01-01

    As a solution to meet a safety requirement to the future full scale space station infrastructure, the Crew Return/Rescue Vehicle (CRV) was supposed to supply the return capability for the complete ISS crew of 7 astronauts back to earth in case of an emergency. A prototype of such a vehicle named X-38 has been developed and built by NASA with European partnership (ESA, DLR). An series of aerial demonstrators (V13x) for tests of the subsonic TAEM phase and the parafoil descent and landing system has been flown by NASA from 1998 to 2001. A full scale unmanned space flight demonstrator (V201) has been built at JSC Houston and although the project has been stopped for budgetary reasons in 2002, it will hopefully still be flown in near future. The X-38 is a lifting body with hypersonic lift to drag ratio about 0.9. In comparison to the Space Shuttle Orbiter, this design provides less aerodynamic maneuvrability and a different actuator layout (divided body flap and winglet rudders instead as combined aileron and elevon in addition to thrust- ers for the early re-entry phase). Hence, the guidance and control concepts used onboard the shuttle orbiter had to be adapted and further developed for the application on the new vehicle. In the frame of the European share of the X-38 project and also of the German TETRA (TEchnol- ogy for future space TRAnsportation) project different GNC related contributions have been made: First, the primary flight control software for the autonomous guidance and control of the X-38 para- foil descent and landing phase has been developed, integrated and successfully flown on multiple vehicles and missions during the aerial drop test campaign conducted by NASA. Second, a real time X-38 vehicle simulator was provided to NASA which has also been used for the validation of a European re-entry guidance and control software (see below). According to the NASA verification and validation plan this simulator is supposed to be used as an independent vali

  9. Nanoscale coatings for erosion and corrosion protection of copper microchannel coolers for high powered laser diodes

    Science.gov (United States)

    Flannery, Matthew; Fan, Angie; Desai, Tapan G.

    2014-03-01

    High powered laser diodes are used in a wide variety of applications ranging from telecommunications to industrial applications. Copper microchannel coolers (MCCs) utilizing high velocity, de-ionized water coolant are used to maintain diode temperatures in the recommended range to produce stable optical power output and control output wavelength. However, aggressive erosion and corrosion attack from the coolant limits the lifetime of the cooler to only 6 months of operation. Currently, gold plating is the industry standard for corrosion and erosion protection in MCCs. However, this technique cannot perform a pin-hole free coating and furthermore cannot uniformly cover the complex geometries of current MCCs involving small diameter primary and secondary channels. Advanced Cooling Technologies, Inc., presents a corrosion and erosion resistant coating (ANCERTM) applied by a vapor phase deposition process for enhanced protection of MCCs. To optimize the coating formation and thickness, coated copper samples were tested in 0.125% NaCl solution and high purity de-ionized (DIW) flow loop. The effects of DIW flow rates and qualities on erosion and corrosion of the ANCERTM coated samples were evaluated in long-term erosion and corrosion testing. The robustness of the coating was also evaluated in thermal cycles between 30°C - 75°C. After 1000 hours flow testing and 30 thermal cycles, the ANCERTM coated copper MCCs showed a corrosion rate 100 times lower than the gold plated ones and furthermore were barely affected by flow rates or temperatures thus demonstrating superior corrosion and erosion protection and long term reliability.

  10. Relationships Between Intensity Gradation and Evolution of Soil Erosion: A Case Study of Changting in Fujian Province, China

    Institute of Scientific and Technical Information of China (English)

    LIN Chen; ZHOU Sheng-Lu; WU Shao-Hua; LIAO Fu-Qiang

    2012-01-01

    Soil erosion gradation is a robust and objective quantitative indicator of soil erosion intensity.Recent applications of soil erosion gradation have focused on monitoring soil erosion with models or simulation of soil erosion through gradation trends.However,soil erosion simulation accuracy is generally being reduced due to the rare consideration of the relationship between soil erosion gradation and erosion evolution.In this study,we investigated different soil erosion intensity grades to demonstrate their sensitivity to types and rates of erosion.Specifically,the objective was to define the relationship between soil erosion gradation and soil erosion evolution in Changting,an undeveloped area in Fujian Province,China,for four time intervals (1975,1990,1999,and 2006).The time series of erosion gradation were developed by modeling analysis with integration of several erosion indicators,and the relationships between the erosion grades and evolution types and rates were quantified.Comparison of the collapsing forces with natural and restoring forces based on human activity demonstrated that there existed an obvious spatial uncertainty in the erosion evolution types,both positive and negative succession coexisted,and the evolution rates were mostly influenced by the force of policy orientation.The impacts of these driving forces were eventually reflected in the erosion intensity gradation and erosion evolution.The correlation between the negative succession rate and erosion intensity gradation was weak and showed a poor contribution to the average succession rate,while the negative correlation between the positive succession rate and erosion intensity gradation would be increasingly clear as time passed.

  11. Demonstration of ethylene controlled ventilation in the storage of tulip bulbs; Demonstratie Ethyleengestuurde ventilatie bij de bewaring van tulpenbollen

    Energy Technology Data Exchange (ETDEWEB)

    Wildschut, J.; Gude, H.

    2006-07-15

    The aim of this demo was to demonstrate the operation of the ethylene sensor and the principle of ethylene controlled ventilation at tulip bulb businesses. Among other things, the demo shows the sensitive and meticulous measuring capacities of the sensor, to what extent the ventilation can be reduced, how much energy can be saved and that the quality of the bulbs improves by reducing dehydration [Dutch] Doel van deze demo was om op tulpenbollenbedrijven de werking van de ethyleensensor en het principe van ethyleengestuurde ventilatie te demonstreren. De demo laat onder meer zien dat de sensor gevoelig en nauwkeurig meet, hoeveel de ventilatie beperkt kan worden, hoeveel de energiebesparing is en dat de kwaliteit van de bollen verbetert door beperking van de uitdroging.

  12. Demonstration of the Dynamic Flowgraph Methodology using the Titan 2 Space Launch Vehicle Digital Flight Control System

    Science.gov (United States)

    Yau, M.; Guarro, S.; Apostolakis, G.

    1993-01-01

    Dynamic Flowgraph Methodology (DFM) is a new approach developed to integrate the modeling and analysis of the hardware and software components of an embedded system. The objective is to complement the traditional approaches which generally follow the philosophy of separating out the hardware and software portions of the assurance analysis. In this paper, the DFM approach is demonstrated using the Titan 2 Space Launch Vehicle Digital Flight Control System. The hardware and software portions of this embedded system are modeled in an integrated framework. In addition, the time dependent behavior and the switching logic can be captured by this DFM model. In the modeling process, it is found that constructing decision tables for software subroutines is very time consuming. A possible solution is suggested. This approach makes use of a well-known numerical method, the Newton-Raphson method, to solve the equations implemented in the subroutines in reverse. Convergence can be achieved in a few steps.

  13. Rain simulator role in creating of Erosion Potential Method (EPM)

    Science.gov (United States)

    Gavrilovic, Zoran; Stefanovic, Milutin; Milovanovic, Irina

    2010-05-01

    Soil erosion is a natural process that depends on many variables factor. Unlike the other factors rain is meteoric phenomenon of short duration and intensity variation. This feature caused the application of rain simulators in the field of erosion research. During the development of erosion potential method, it was concluded that there is too large dissipation of observed erosion data. The first use of simulators did not give better results, because the rain simulator had no impact on other factors of erosion. Therefore, the research continued in the laboratory where the use of rain simulators takes a series of data for various intensity and duration of rain. Other factors are controlled for each series of measurements were constant. These data enabled more precise definition of the numerical coefficients and procedures of erosion potential method (EPM), which is known in the scientific public as Gavrilovic method. The paper will appear applied a combination of experimental erosion field and laboratory measurements obtained using rain simulators. Key words: Erosion, torrents, meteorology, climate, Rain simulator

  14. Geoinformation mapping of soil erosion in the Middle Volga region

    Science.gov (United States)

    Yermolaev, O. P.

    2017-01-01

    The results of a medium-scale geoinformation mapping of soil erosion on an area of about 150000 km2 in the Middle Volga region are analyzed using the catchment-based approach. A quantitative index of the development of soil erosion on the agricultural lands is suggested. It reflects the intensity of soil erosion on slopes within the river catchments. A computer-based vector map of the boundaries of 3331 elementary catchments has been developed. It represents the territorial units for the analysis of soil erosion. Archive materials from the former institutes for land survey have been used to compile a series of the maps of soil erosion in river catchments on a scale of 1: 200000. The zoning of erosional processes has been performed, and the natural and anthropogenic levels of soil erosion in different basins have been estimated. The analysis of these materials shows that the topography and agricultural activity of humans are the major factors controlling the development of erosion. The maximum development of soil erosion in the studied region is typical of the subzone of broadleaved forests.

  15. Reprint of: Assessment of the use of sediment fences for control of erosion and sediment phosphorus loss after potato harvesting on sloping land.

    Science.gov (United States)

    Vinten, A J A; Loades, K; Addy, S; Richards, S; Stutter, M; Cook, Y; Watson, H; Taylor, C; Abel, C; Baggaley, N; Ritchie, R; Jeffrey, W

    2014-01-15

    In humid temperate areas, after harvest of potatoes, it is difficult to prevent soil erosion and diffuse pollution. In some autumn weather conditions, in-field mitigation such as cultivation or sowing are not possible, while edge of field measures can be costly and inflexible. We have assessed the potential of modified sediment fences, widely used on building sites, for erosion mitigation post-harvest of potato crops. Field scale assessments were conducted on fields in the Lunan catchment, eastern Scotland. Sediment retention was estimated by two methods: a topographic survey method using a hand held Real Time Kinematic Global Positioning System (RTK-GPS), and direct measurement of sediment depth using a graduated cane. In the 2010/11 trial the main fence comprised 70 m of entrenched fine mesh (0.25 mm) and coarser mesh (4mm) fabric pinned to a contour fence near the base of the field. This retained an estimated 50.9 m(3) (80.2 tonnes) of sediment, with weighted mean total P (TP) content of 0.09 % in the<2mm soil fraction. In the 2011/12 trial, the main 146 m fence was of intermediate mesh size (1.2mm). The fence was partitioned into nine upslope plots, with 3 replicates of each of 3 cultivation methods: T1 (full grubbing--a light, tined cultivator), T2 (partial grubbing) and T3 (no grubbing). Average plot slopes ranged from 9.9 to 11.0 %. The amounts of TP accumulating as sediment at the fences were: 9.3 (sd=7.8), 11.8 (sd=10.2) and 25.7 (sd=5.8)kg P/ha of upslope plot for the T1, T2 and T3 treatments respectively.

  16. Assessment of the use of sediment fences for control of erosion and sediment phosphorus loss after potato harvesting on sloping land.

    Science.gov (United States)

    Vinten, A J A; Loades, K; Addy, S; Richards, S; Stutter, M; Cook, Y; Watson, H; Taylor, C; Abel, C; Baggaley, N; Ritchie, R; Jeffrey, W

    2014-01-15

    In humid temperate areas, after harvest of potatoes, it is difficult to prevent soil erosion and diffuse pollution. In some autumn weather conditions, in-field mitigation such as cultivation or sowing are not possible, while edge of field measures can be costly and inflexible. We have assessed the potential of modified sediment fences, widely used on building sites, for erosion mitigation post-harvest of potato crops. Field scale assessments were conducted on fields in the Lunan catchment, eastern Scotland. Sediment retention was estimated by two methods: a topographic survey method using a hand held Real Time Kinematic Global Positioning System (RTK-GPS), and direct measurement of sediment depth using a graduated cane. In the 2010/11 trial the main fence comprised 70 m of entrenched fine mesh (0.25 mm) and coarser mesh (4mm) fabric pinned to a contour fence near the base of the field. This retained an estimated 50.9 m(3) (80.2 tonnes) of sediment, with weighted mean total P (TP) content of 0.09 % in the<2mm soil fraction. In the 2011/12 trial, the main 146 m fence was of intermediate mesh size (1.2mm). The fence was partitioned into nine upslope plots, with 3 replicates of each of 3 cultivation methods: T1 (full grubbing--a light, tined cultivator), T2 (partial grubbing) and T3 (no grubbing). Average plot slopes ranged from 9.9 to 11.0 %. The amounts of TP accumulating as sediment at the fences were: 9.3 (sd = 7.8), 11.8 (sd = 10.2) and 25.7 (sd = 5.8)kg P/ha of upslope plot for the T1, T2 and T3 treatments respectively.

  17. Field studies of beach cones as coastal erosion control/reversal devices for areas with significant oil and gas activities. Final report, February 24, 1992--September 18, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Law, V.J.

    1995-09-18

    The primary objective of this project was to evaluate the utility of a device called the {open_quotes}beach cone{close_quotes} in combating coastal erosion. Seven initial sites were selected for testing beach cones in a variety of geometric configurations. Permits were obtained from the State of Louisiana and the U.S. Army Corps of Engineers to perform the work associated with this study. Six hundred beach cones were actually installed at six of the sites in late July and early August, 1992. Findings indicate that beach cones accreted significant amounts of materials along the beach of a barrier island, and they might have been instrumental in repairing an approximately 200 meter gap in the island. At the eighth installation the amount of accreted material was measured by surveys to be 2200 cubic meters (2900 cubic yards) in February of 1993, when the cones were found to have been completely covered by the material. At other test sites, accretion rates have been less dramatic but importantly, no significant additional erosion has occurred, which is a positive result. The cost of sediment accretion using beach cones was found to be about $13.72 per cubic yard, which would be much lower if the cones were mass produced (on the order of $3.00 per cubic yard). The survival of the cones through the fringes of Hurricane Andrew indicates that they can be anchored sufficiently to survive significant storms. The measurements of the cones settling rates indicate that this effect is not significant enough to hinder their effectiveness. A subcontract to Xavier University to assess the ecological quality of the experimental sites involved the study of the biogeochemical cycle of trace metals. The highest concentration of heavy metals were near a fishing camp while the lowest levels were in the beach sand of a barrier island. This suggests that the metals do not occur naturally in these areas, but have been placed in the sediments by man`s activities.

  18. An application of mathematical models to select the optimal alternative for an integral plan to desertification and erosion control (Chaco Area - Salta Province - Argentina)

    Science.gov (United States)

    Grau, J. B.; Antón, J. M.; Tarquis, A. M.; Colombo, F.; de Los Ríos, L.; Cisneros, J. M.

    2010-11-01

    Multi-criteria Decision Analysis (MCDA) is concerned with identifying the values, uncertainties and other issues relevant in a given decision, its rationality, and the resulting optimal decision. These decisions are difficult because the complexity of the system or because of determining the optimal situation or behaviour. This work will illustrate how MCDA is applied in practice to a complex problem to resolve such us soil erosion and degradation. Desertification is a global problem and recently it has been studied in several forums as ONU that literally says: "Desertification has a very high incidence in the environmental and food security, socioeconomic stability and world sustained development". Desertification is the soil quality loss and one of FAO's most important preoccupations as hunger in the world is increasing. Multiple factors are involved of diverse nature related to: natural phenomena (water and wind erosion), human activities linked to soil and water management, and others not related to the former. In the whole world this problem exists, but its effects and solutions are different. It is necessary to take into account economical, environmental, cultural and sociological criteria. A multi-criteria model to select among different alternatives to prepare an integral plan to ameliorate or/and solve this problem in each area has been elaborated taking in account eight criteria and five alternatives. Six sub zones have been established following previous studies and in each one the initial matrix and weights have been defined to apply on different criteria. Three multicriteria decision methods have been used for the different sub zones: ELECTRE, PROMETHEE and AHP. The results show a high level of consistency among the three different multicriteria methods despite the complexity of the system studied. The methods are fully described for La Estrella sub zone, indicating election of weights, Initial Matrixes, algorithms used for PROMETHEE, and the Graph of

  19. The nature of riverbank erosion along the South River, Virginia revealed through terrestrial laser-scanner surveys

    Science.gov (United States)

    O'Neal, M. A.; Pizzuto, J. E.

    2012-12-01

    We surveyed 23 eroding banks along the South River, Virginia between 2006 and 2008 CE using a terrestrial laser scanner. At 6 sites with varying bank vegetation, soil type, and geomorphic settings, a total of 11 repeat surveys were completed to document rates and spatial patterns of contemporary bank erosion. Time intervals between surveys ranged from 89 days to 421 days. Our survey data, averaging 15,000 points per square meter, were manually and mathematically filtered to remove non-bank elements and converted into 0.05 m x 0.05 m gridded models. Comparison of our data-dense, mathematically filtered models indicates that the streamwise spatial extent of significant erosion varied from 0% to about 80% of the surveyed bank area. Annualized maximum rates of localized bank erosion varied from 0 to about 2.4 m/yr, the latter of which greatly exceeds estimated rates from historical aerial photographs. Comparison of our LIDAR-derived erosion rates, with those from field observations, identified the geologic setting (i.e. bank material type) as the most important control on the extent of bank erosion and suggests that large trees can reduce erosion rates. Model comparisons indicate that maximum erosion along the forested banks focused around leaning trees, while elsewhere the extent of bank retreat was negligible. On grassy banks, retreat was controlled by the creation of small overhanging clumps of turf at the top of the bank, their occasional failure, and the ultimate removal of failed debris from the bank toe. Partial autocorrelation analysis of vertically integrated bank retreat at two eroding banks demonstrates that bank profile erosion is virtually uncorrelated at horizontal distances greater than about 1 m, a length scale of approximately half the bank height. This extensive streamwise variability suggests that widely spaced profile data cannot adequately represent bank erosion at these sites. Additional analysis of our comprehensive spatial data also indicates

  20. Insula Demonstrates a Non-Linear Response to Varying Demand for Cognitive Control and Weaker Resting Connectivity With the Executive Control Network in Smokers.

    Science.gov (United States)

    Fedota, John R; Matous, Allison L; Salmeron, Betty Jo; Gu, Hong; Ross, Thomas J; Stein, Elliot A

    2016-09-01

    Deficits in cognitive control processes are a primary characteristic of nicotine addiction. However, while network-based connectivity measures of dysfunction have frequently been observed, empirical evidence of task-based dysfunction in these processes has been inconsistent. Here, in a sample of smokers (n=35) and non-smokers (n=21), a previously validated parametric flanker task is employed to characterize addiction-related alterations in responses to varying (ie, high, intermediate, and low) demands for cognitive control. This approach yields a demand-response curve that aims to characterize potential non-linear responses to increased demand for control, including insensitivities or lags in fully activating the cognitive control network. We further used task-based differences in activation between groups as seeds for resting-state analysis of network dysfunction in an effort to more closely link prior inconsistencies in task-related activation with evidence of impaired network connectivity in smokers. For both smokers and non-smokers, neuroimaging results showed similar increases in activation in brain areas associated with cognitive control. However, reduced activation in right insula was seen only in smokers and only when processing intermediate demand for cognitive control. Further, in smokers, this task-modulated right insula showed weaker functional connectivity with the superior frontal gyrus, a component of the task-positive executive control network. These results demonstrate that the neural instantiation of salience attribution in smokers is both more effortful to fully activate and has more difficulty communicating with the exogenous, task-positive, executive control network. Together, these findings further articulate the cognitive control dysfunction associated with smoking and illustrate a specific brain circuit potentially responsible.

  1. Effect of carbides on erosion resistance of 23-8-N steel

    Indian Academy of Sciences (India)

    Aniruddha A Gadhikar; Ashok Sharma; D B Goel; C P Sharma

    2014-04-01

    Microstructure is one of the most important parameters influencing erosion behaviour of materials. The role of carbides in the matrix is very complicated in controlling the erosion rate of the materials. Conflicting results have been reported in the literature about the effect of carbides on erosion resistance. Carbides are of great importance especially as obstacles against the penetration of erosive particles into the material surface. However, they are susceptible to cracking and causing matrix decohesion which may increase the overall erosion rate. In 23-8-N nitronic steel, carbides present in the form of bands are observed to accelerate the erosion rate. Coarse carbides cause depletion of carbon in the austenite matrix which adversely affects the strain hardening tendency thus causing deterioration in erosion resistance of the bulk material. The dissolution of carbides in the austenitic matrix after solution annealing is observed to improve the erosion resistance of 23-8-N nitronic steel.

  2. Rill erosion rates in burned forests

    Science.gov (United States)

    Joseph W. Wagenbrenner; Peter R. Robichaud

    2011-01-01

    Introduction Wildfires often produce large increases in runoff and erosion rates (e.g., Moody and Martin, 2009), and land managers need to predict the frequency and magnitude of postfire erosion to determine the needs for hazard response and possible erosion mitigation to reduce the impacts of increased erosion on public safety and valued resources. The Water Erosion...

  3. Combined impacts of land use and soil property changes on soil erosion in a mollisol area under long-term agricultural development.

    Science.gov (United States)

    Ouyang, Wei; Wu, Yuyang; Hao, Zengchao; Zhang, Qi; Bu, Qingwei; Gao, Xiang

    2017-09-22

    Soil erosion exhibits special characteristics in the process of agricultural development. Understanding the combined impacts of land use and soil property changes on soil erosion, especially in the area under long-term agricultural cultivations, is vital to watershed agricultural and soil management. This study investigated the temporal-spatial patterns of the soil erosion based on a modified version of Universal Soil Loss Equation (USLE) and conducted a soil erosion contribution analysis. The land use data were interpreted from Landsat series images, and soil properties were obtained from field sampling, laboratory tests and SPAW (Soil-Plant-Atmosphere-Water) model calculations. Over a long period of agricultural development, the average erosion modulus decreased from 187.7tkm(-2)a(-1) in 1979 to 158.4tkm(-2)a(-1) in 2014. The land use types were transformed mainly in the reclamation of paddy fields and the shrinking of wetlands on a large scale. Most of the soils were converted to loam from silty or clay loam and the saturated hydraulic conductivity (Ks) of most soil types decreased by 1.11% to 43.6%. The rapidly increasing area of 49.8km(2) of paddy fields together with the moderate decrease of 14.0km(2) of forests, as well as Ks values explained 87.4% of the total variance in soil erosion. Although changes in soil physical and water characteristics indicated that soil erosion loads should have become higher, the upsurge in paddy fields played an important role in mitigating soil erosion in this study area. These results demonstrated that land use changes had more significant impacts than soil property changes on soil erosion. This study suggested that rational measures should be taken to extend paddy fields and control the dry land farming. These findings will benefit watershed agricultural targeting and management. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. The real-time control system for the CANARY multi-object adaptive optics on-sky demonstrator

    Science.gov (United States)

    Dipper, N. A.; Basden, A.; Looker, N. E.; Gendron, E.; Geng, D.; Gratadour, D.; Hubert, Z.; Vidal, F.; Myers, R. M.; Rousset, G.; Sevin, A.; Younger, E. J.

    2010-07-01

    CANARY is a Multi-Object Adaptive Optics (MOAO) system designed to demonstrate the AO aspects of proposed EELT instruments such as the multi-object spectrograph EAGLE. The first phase of Canary will be executed on the 4.2m William Herschel Telescope in 2010. We describe here the AO Real-time Control System (RTCS) for Canary. This is based on a distributed architecture of components interconnected by a fast serial fabric (sFPDP). The hardware used is a hybrid of FPGA and CPU technology. The middleware used for system data telemetry and control is based on CORBA and the publish/subscribe pattern. The system is designed to be easily modified and extended for the later, higher order, phases of CANARY. In order to provide the increase in computational power required in higher order systems, the current CPU technology can be readily replaced by acceleration hardware based on FPGA or GPU technologies. The Canary RTCS thus provides a test-bed for these new technologies that will be required for E-ELT instruments. These design concepts can be developed to provide an RTCS for E-ELT instruments and are in line with those under consideration by ESO for the E-ELT AO systems to which instruments such as EAGLE will be required to interface.

  5. First quantification of severe wind erosion in yardang fields using cosmogenic 10Be within the western Qaidam Basin, China

    Science.gov (United States)

    Rohrmann, A.; Heermance, R.; Kapp, P. A.; Mc-Callister, A.

    2010-12-01

    Desert environments are a major source of global loess and may undergo substantial wind-erosion as evidenced by yardangs, which are streamlined bedrock ridges sculpted from uni-directional winds. However, there are few quantitative estimates of wind erosion rates in deflationary deserts, globally. Here, we report the first quantitative rates of bedrock wind erosion determined using cosmogenic 10Be in the western Qaidam basin, China, where roughly one-third of the modern basin floor (~3.88 × 104 km2) exposes yardangs. Eleven Neogene bedrock sandstone samples and one pre-Cenozoic granite sample were analyzed for 10Be concentrations. The Neogene samples were collected from crests and limbs of broad and actively growing anticlines, where in most places strata have been wind-sculpted into yardangs. Sedimentary bedrock erosion rates vary from 0.04-0.34 mm/yr, although 60 percent (n=7) of all samples cluster tightly at 0.1 ± 0.03 mm/yr. Erosion rates assume steady-state erosion over ~10,000 years. The lowest rate of 0.0025 mm/yr was obtained from a granite bedrock sample along the Altyn-Tagh range bounding the northwestern margin of the Qaidam basin and is consistent with other 10Be bedrock erosion rates collected from granitic bedrock elsewhere on the Tibetan Plateau. These results demonstrate the importance of lithology in controlling bedrock erodibility by wind. The highest erosion rates of 0.17, 0.25, and 0.34 mm/yr were determined along a transect across an active anticline. The lowest of the three rates was obtained from the top of the structure, suggesting that wind erosion and thus wind speeds are highest on the limbs of an anticline as wind is forced around the obstacle (Bernoulli-effect), rather than flowing over it. The determined sedimentary bedrock erosion rates of 0.04-0.34 mm/yr are in good agreement with previous analysis of basin wide-average erosion rates from geological cross-sections (0.29 mm/yr) and simple erosion calculations using previous lake

  6. STUDY ON EROSION RESISTANCE PROPERTIES OF O'-SIALON-BN IN MOLTEN STEEL

    Institute of Scientific and Technical Information of China (English)

    Q. Zhen; W.Z. Ding; W.C. Li

    2001-01-01

    The erosion resistance properties of O'-Sialon-BN in molten steel are investigated in this work. According to experimental results and theoretical analysis, BN in O'Sialon-BN plays an important role in molten steel erosion resistance. And the erosion kinetics of the O'-Sialon-BN composites in molten steel is controlled by two stages:the first one is controlled by chemical reaction taking place on the interface; the second one is controlled by diffusion. The erosion surface of the materials is also investigated with fractal theory. The results show that the fractal dimensions of the erosion surface vary with erosion time from a linear way to parabolic way, which relates to the change of erosion mechanism from interface chemical reaction to diffusion.

  7. Erosion--Corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Vyas, B.

    1978-01-01

    The deterioration of materials by corrosion or erosion by itself presents a formidable problem and for this reason investigators have studied these two phenomena independently. In fact, there are very few systematic studies on E-C and the majority of references mention it only in passing. In most real systems, however, the two destructive processes take place simultaneously, hence the purpose of this review is to present the various interactions between the chemical and mechanical agents leading to accelerated degradation of the material. The papers cited in the review are those that lead to a better understanding of the process involved in the accelerated rate of material loss under E-C conditions.

  8. Dune erosion under climate change

    NARCIS (Netherlands)

    de Winter, R.C.|info:eu-repo/dai/nl/341476935

    2014-01-01

    This PhD-thesis investigated the effect of future climate change on dune erosion in the Netherlands. At present, dune erosion occurs under a combination of large storm surge and high waves, which are both generated by a storm event. Therefore to investigate the affect of future climate change on dun

  9. Nocturnal lagophthalmos and recurrent erosion.

    Science.gov (United States)

    Sturrock, G. D.

    1976-01-01

    The symptoms and corneal changes caused by sleeping with one or both eyes open are described in 102 patients. The clinical picture is identical to that of the microform recurrent erosion. The close relationship between the micro- and macro-forms of recurrent corneal erosion suggests that the latter condition is also precipitated by nocturnal lagophthalmos. Images PMID:1268178

  10. Dune erosion under climate change

    NARCIS (Netherlands)

    de Winter, R.C.

    2014-01-01

    This PhD-thesis investigated the effect of future climate change on dune erosion in the Netherlands. At present, dune erosion occurs under a combination of large storm surge and high waves, which are both generated by a storm event. Therefore to investigate the affect of future climate change on dun

  11. Dune erosion during storm surges

    NARCIS (Netherlands)

    Van Thiel de Vries, J.S.M.

    2009-01-01

    Large parts of The Netherlands are protected from flooding by a narrow strip of sandy beaches and dunes. The aim of this thesis is to extend the existing knowledge of dune erosion during storm surges as it occurs along the Dutch coast. The thesis discusses: • A large scale dune erosion experiment to

  12. The erosive potential of lollipops

    NARCIS (Netherlands)

    Brand, H.S.; Gambon, D.L.; Paap, A.; Bulthuis, M.S.; Veerman, E.C.I.; Nieuw Amerongen, A.V.

    2009-01-01

    Aim: To determine the erosive potential of several commercially available lollipops and the protective effect of saliva. Methods: The erosive potential of lollipops was determined in vitro by measuring the pH and neutralisable acidity. Subsequently, 10 healthy volunteers tested different types of lo

  13. The impact of the streamflow hydrograph on sediment supply from terrace erosion

    Science.gov (United States)

    Higson, John Lee; Singer, Michael Bliss

    2015-11-01

    Sediment supply from banks and terraces has important implications for grain-size distributions in alluvial rivers (and by extension for aquatic habitat), as well as for the delivery of floodplain-stored nutrients and contaminants to the aquatic environment. The interactions between streamflow hydrographs and lateral channel boundary failure control the sediment supply from banks and terraces. However, the relationships between variable flow and discrete sediment supply from catastrophic erosion of lateral boundaries and subsequent mass sediment flux in rivers are not well characterised by existing methods and models that focus only on one of several relevant interrelated processes. In order to improve predictive capability of catastrophic sediment supply from lateral boundaries, we adopt a new approach to modelling the process interactions between stream hydrology, erosion of banks/terraces, and the corresponding discrete supply of sediment to channels. We develop a modelling framework for terrace - channel coupling that combines existing theories of flow through porous media, bank stability, and fractional sediment flux. We demonstrate the utility of this modelling approach by assessing hydrologically driven erosion, evolution of grain size in the channel, and fine sediment flux from a study site along the Yuba River in California over individual flood hydrographs and over decadal historical flow series. We quantify the supply of sediment eroded from a contaminated nineteenth century fan terrace of hydraulic gold mining tailings intersecting the Yuba, and find that a threshold for erosion exists at a stage in the channel in excess of 8 m producing episodic sediment concentrations in excess of 300 mg L-1. The modelling produced erosion and fine sediment pulses from each of three major floods in the past several decades until the flow drops below 500 m3 s-1 and a bed armor layer forms, while no sediment was generated from the terrace during smaller floods. We

  14. Lava channel formation during the 2001 eruption on Mount Etna: evidence for mechanical erosion

    CERN Document Server

    Ferlito, C; Ferlito, Carmelo; Siewert, Jens

    2005-01-01

    We report the direct observation of a peculiar lava channel that was formed near the base of a parasitic cone during the 2001 eruption on Mount Etna. Erosive processes by flowing lava are commonly attributed to thermal erosion. However, field evidence strongly suggests that models of thermal erosion cannot explain the formation of this channel. Here, we put forward the idea that the essential erosion mechanism was abrasive wear. By applying a simple model from tribology we demonstrate that the available data agree favorably with our hypothesis. Consequently, we propose that erosional processes resembling the wear phenomena in glacial erosion are possible in a volcanic environment.

  15. Lava Channel Formation during the 2001 Eruption on Mount Etna: Evidence for Mechanical Erosion

    Science.gov (United States)

    Ferlito, Carmelo; Siewert, Jens

    2006-01-01

    We report the direct observation of a peculiar lava channel that was formed near the base of a parasitic cone during the 2001 eruption on Mount Etna. Erosive processes by flowing lava are commonly attributed to thermal erosion. However, field evidence strongly suggests that models of thermal erosion cannot explain the formation of this channel. Here, we put forward the idea that the essential erosion mechanism was abrasive wear. By applying a simple model from tribology we demonstrate that the available data agree favorably with our hypothesis. Consequently, we propose that erosional processes resembling the wear phenomena in glacial erosion are possible in a volcanic environment.

  16. ‘Natural experiment’ Demonstrates Top-Down Control of Spiders by Birds on a Landscape Level

    Science.gov (United States)

    Rogers, Haldre; Hille Ris Lambers, Janneke; Miller, Ross; Tewksbury, Joshua J.

    2012-01-01

    The combination of small-scale manipulative experiments and large-scale natural experiments provides a powerful approach for demonstrating the importance of top-down trophic control on the ecosystem scale. The most compelling natural experiments have come from studies examining the landscape-scale loss of apex predators like sea otters, wolves, fish and land crabs. Birds are dominant apex predators in terrestrial systems around the world, yet all studies on their role as predators have come from small-scale experiments; the top-down impact of bird loss on their arthropod prey has yet to be examined at a landscape scale. Here, we use a unique natural experiment, the extirpation of insectivorous birds from nearly all forests on the island of Guam by the invasive brown tree snake, to produce the first assessment of the impacts of bird loss on their prey. We focused on spiders because experimental studies showed a consistent top-down effect of birds on spiders. We conducted spider web surveys in native forest on Guam and three nearby islands with healthy bird populations. Spider web densities on the island of Guam were 40 times greater than densities on islands with birds during the wet season, and 2.3 times greater during the dry season. These results confirm the general trend from manipulative experiments conducted in other systems however, the effect size was much greater in this natural experiment than in most manipulative experiments. In addition, bird loss appears to have removed the seasonality of spider webs and led to larger webs in at least one spider species in the forests of Guam than on nearby islands with birds. We discuss several possible mechanisms for the observed changes. Overall, our results suggest that effect sizes from smaller-scale experimental studies may significantly underestimate the impact of bird loss on spider density as demonstrated by this large-scale natural experiment. PMID:22970126

  17. Experiments for understanding soil erosion processes

    Science.gov (United States)

    Seeger, Manuel

    2015-04-01

    Soil erosion processes are usually quantified by observation and measurement of their related forms. Rill, and gullies, moulds or sediment sinks are often used to estimate the soil loss. These forms are generally related directly to different types of processes, thus are also used to identify the dominant processes on a certain type of land-use. Nevertheless, the direct observation of erosion processes is constrained by their temporal and spatial erratic occurrence. As a consequence, the process understanding is generally deduced by analogies. Another possibility is to reproduce processes in experiments in both, the lab and in the field. Laboratory experiments are implemented when we want to have full control over all parameters we think are relevant for the process in our focus. So are very useful for identification of parameters influencing processes and their intensities, but also as physical models of the processes and process interactions in our focus. Therefore, we can use them to verify our concepts, and to define relevant parameters. Field experiments generally only simulate with controlled driving forces, this is the rain or the runoff, but dealing with the uncertainty of our study object, the soil. This enables two things: 1) similar as with lab experiments, we are able to identify processes and process interactions and so, to get a deeper understanding of soil erosion; 2) experiments are suitable for providing data about singular processes in the field and thus, to provide data suitable for model parametrisation and calibration. These may be quantitative data about erodibility or soil resistance, sediment detachment or transport. The Physical Geography Group at Trier University has a long lasting experience in the application of experiments in soil erosion research in the field, and has become lead in the further development conception and of devices and procedures to investigate splash detachment and initial transport of soil particles by wind and water

  18. Mathematical model to select the optimal alternative for an integral plan to desertification and erosion control for the Chaco Area in Salta Province (Argentine)

    Science.gov (United States)

    Grau, J. B.; Anton, J. M.; Tarquis, A. M.; Colombo, F.; de Los Rios, L.; Cisneros, J. M.

    2010-04-01

    Multi-criteria Decision Analysis (MCDA) is concerned with identifying the values, uncertainties and other issues relevant in a given decision, its rationality, and the resulting optimal decision. These decisions are difficult because the complexity of the system or because of determining the optimal situation or behavior. This work will illustrate how MCDA is applied in practice to a complex problem to resolve such us soil erosion and degradation. Desertification is a global problem and recently it has been studied in several forums as ONU that literally says: "Desertification has a very high incidence in the environmental and food security, socioeconomic stability and world sustained development". Desertification is the soil quality loss and one of FAO's most important preoccupations as hunger in the world is increasing. Multiple factors are involved of diverse nature related to: natural phenomena (water and wind erosion), human activities linked to soil and water management, and others not related to the former. In the whole world this problem exists, but its effects and solutions are different. It is necessary to take into account economical, environmental, cultural and sociological criteria. A multi-criteria model to select among different alternatives to prepare an integral plan to ameliorate or/and solve this problem in each area has been elaborated taking in account eight criteria and six alternatives. Six sub zones have been established following previous studies and in each one the initial matrix and weights have been defined to apply on different criteria. Three Multicriteria Decision Methods have been used for the different sub zones: ELECTRE, PROMETHEE and AHP. The results show a high level of consistency among the three different multicriteria methods despite the complexity of the system studied. The methods are described for La Estrella sub zone, indicating election of weights, Initial Matrixes, the MATHCAD8 algorithms used for PROMETHEE, and the

  19. An application of mathematical models to select the optimal alternative for an integral plan to desertification and erosion control (Chaco Area – Salta Province – Argentina

    Directory of Open Access Journals (Sweden)

    J. B. Grau

    2010-11-01

    Full Text Available Multi-criteria Decision Analysis (MCDA is concerned with identifying the values, uncertainties and other issues relevant in a given decision, its rationality, and the resulting optimal decision. These decisions are difficult because the complexity of the system or because of determining the optimal situation or behaviour. This work will illustrate how MCDA is applied in practice to a complex problem to resolve such us soil erosion and degradation. Desertification is a global problem and recently it has been studied in several forums as ONU that literally says: "Desertification has a very high incidence in the environmental and food security, socioeconomic stability and world sustained development". Desertification is the soil quality loss and one of FAO's most important preoccupations as hunger in the world is increasing. Multiple factors are involved of diverse nature related to: natural phenomena (water and wind erosion, human activities linked to soil and water management, and others not related to the former. In the whole world this problem exists, but its effects and solutions are different. It is necessary to take into account economical, environmental, cultural and sociological criteria. A multi-criteria model to select among different alternatives to prepare an integral plan to ameliorate or/and solve this problem in each area has been elaborated taking in account eight criteria and five alternatives. Six sub zones have been established following previous studies and in each one the initial matrix and weights have been defined to apply on different criteria. Three multicriteria decision methods have been used for the different sub zones: ELECTRE, PROMETHEE and AHP. The results show a high level of consistency among the three different multicriteria methods despite the complexity of the system studied. The methods are fully described for La Estrella sub zone, indicating election of weights, Initial Matrixes, algorithms used

  20. Using REE Tracers to Measure Sheet Erosion Changing to Rill Erosion

    Institute of Scientific and Technical Information of China (English)

    宋炜; 刘普灵; 杨明义; 薛亚洲

    2003-01-01

    Rare earth element(REE) tracer method was used to study sheet erosion changing to rill erosion on slope land. By placing different REE on different soil depth across a slope in an indoor plot, two simulated rainfalls were applied to study the change of erosion type and the rill erosion process. The results indicate that the main erosion type is sheet erosion at the beginning of the rainfalls, and serious erosion happens after rill erosion appears. Accumulated sheet and rill erosion amount increases with the rainfalls time. The percentage of sheet erosion amount decreases and rill erosion percentage increases with time. At the end of the rainfalls, the total rill erosion amounts are 4.3 and 5 times more than sheet erosion. In this paper, a new REE tracer method was used to quantitatively distinguish sheet and rill erosion amount. The new REE tracer method should be useful to future studying of erosion processes on slope lands.

  1. Prevention of dentine erosion by brushing with anti-erosive toothpastes.

    Science.gov (United States)

    Aykut-Yetkiner, Arzu; Attin, Thomas; Wiegand, Annette

    2014-07-01

    This in vitro study aimed to investigate the preventive effect of brushing with anti-erosive toothpastes compared to a conventional fluoride toothpaste on dentine erosion. Bovine dentine specimens (n=12 per subgroup) were eroded in an artificial mouth (6 days, 6×30 s/day) using either citric acid (pH:2.5) or a hydrochloric acid/pepsin solution (pH:1.6), simulating extrinsic or intrinsic erosive conditions, respectively. In between, the specimens were rinsed with artificial saliva. Twice daily, the specimens were brushed for 15 s in an automatic brushing machine at 2.5 N with a conventional fluoride toothpaste slurry (elmex, AmF) or toothpaste slurries with anti-erosive formulations: Apacare (NaF/1% nHAP), Biorepair (ZnCO3-HAP), Chitodent (Chitosan), elmex Erosionsschutz (NaF/AmF/SnCl2/Chitosan), mirasensitive hap (NaF/30% HAP), Sensodyne Proschmelz (NaF/KNO3). Unbrushed specimens served as control. Dentine loss was measured profilometrically and statistically analysed using two-way and one-way ANOVA followed by Scheffe's post hoc tests. RDA-values of all toothpastes were determined, and linear mixed models were applied to analyse the influence of toothpaste abrasivity on dentine wear (p<0.05). Dentine erosion of unbrushed specimens amounted to 5.1±1.0 μm (extrinsic conditions) and 12.9±1.4 μm (intrinsic conditions). All toothpastes significantly reduced dentine erosion by 24-67% (extrinsic conditions) and 21-40% (intrinsic conditions). Biorepair was least effective, while all other toothpastes were not significantly different from each other. Linear mixed models did not show a significant effect of the RDA-value of the respective toothpaste on dentine loss. Toothpastes with anti-erosive formulations reduced dentine erosion, especially under simulated extrinsic erosive conditions, but were not superior to a conventional fluoride toothpaste. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Developing and demonstrating low-energy climate control and production techniques for greenhouse-grown citrus and ornamental crops

    Energy Technology Data Exchange (ETDEWEB)

    Bodnaruk, W.H. Jr.

    1983-04-01

    The aim of this study was to develop and demonstrate low energy climate control and production techniques for greenhouse grown citrus and ornamental crops. Emphasis was placed on design, fuel efficiency and plant response to warm water soil heating systems using solar energy and LP gas. An energy requirement of 28Btus output per hour per square foot of bed space will provide soil temperature of 70/sup 0/F minimum when air temperatures are maintained at 60/sup 0/F. Soil heating to 70/sup 0/ increased rooting and growth of 8 foliage plant varieties by 25 to 45% compared to plants grown under 60/sup 0/F air temperature conditions. Providing soil heating, however, increased fuel consumption in the central Florida test facilities by 30% in the winters of 1980-81 and 1981-82. Solar tie-in to soil heating systems has the potential of reducing fuel usage. Solar heated water provided 4 hours of soil heating following a good collection day. Decreased in-bed pipe spacing and increased storage capacity should increase the solar percentage to 6 hours.

  3. Analysis on LID for highly urbanized areas' waterlogging control: demonstrated on the example of Caohejing in Shanghai.

    Science.gov (United States)

    Liao, Z L; He, Y; Huang, F; Wang, S; Li, H Z

    2013-01-01

    Although a commonly applied measure across the United States and Europe for alleviating the negative impacts of urbanization on the hydrological cycle, low impact development (LID) has not been widely used in highly urbanized areas, especially in rapidly urbanizing cities in developing countries like China. In this paper, given five LID practices including Bio-Retention, Infiltration Trench, Porous Pavement, Rain Barrels, and Green Swale, an analysis on LID for highly urbanized areas' waterlogging control is demonstrated using the example of Caohejing in Shanghai, China. Design storm events and storm water management models are employed to simulate the total waterlogging volume reduction, peak flow rate reduction and runoff coefficient reduction of different scenarios. Cost-effectiveness is calculated for the five practices. The aftermath shows that LID practices can have significant effects on storm water management in a highly urbanized area, and the comparative results reveal that Rain Barrels and Infiltration Trench are the two most suitable cost-effective measures for the study area.

  4. Erosive Burning Study Utilizing Ultrasonic Measurement Techniques

    Science.gov (United States)

    Furfaro, James A.

    2003-01-01

    A 6-segment subscale motor was developed to generate a range of internal environments from which multiple propellants could be characterized for erosive burning. The motor test bed was designed to provide a high Mach number, high mass flux environment. Propellant regression rates were monitored for each segment utilizing ultrasonic measurement techniques. These data were obtained for three propellants RSRM, ETM- 03, and Castor@ IVA, which span two propellant types, PBAN (polybutadiene acrylonitrile) and HTPB (hydroxyl terminated polybutadiene). The characterization of these propellants indicates a remarkably similar erosive burning response to the induced flow environment. Propellant burnrates for each type had a conventional response with respect to pressure up to a bulk flow velocity threshold. Each propellant, however, had a unique threshold at which it would experience an increase in observed propellant burn rate. Above the observed threshold each propellant again demonstrated a similar enhanced burn rate response corresponding to the local flow environment.

  5. Granular and Dissolved Polyacrylamide Effects on Erosion and Runoff under Simulated Rainfall.

    Science.gov (United States)

    Kang, Jihoon; Amoozegar, Aziz; Heitman, Joshua L; McLaughlin, Richard A

    2014-11-01

    Polyacrylamide (PAM) has been demonstrated to reduce erosion under many conditions, but less is known about the effects of its application method on erosion and concentrations in the runoff water. A rainfall simulation study was conducted to evaluate the performance of an excelsior erosion control blanket (cover) and two PAM application methods. The treatments were (i) no cover + no PAM (control), (ii) cover + no PAM, (iii) cover + granular PAM (GPAM), and (iv) cover + dissolved PAM (DPAM) applied to soil packed in wooden runoff boxes. The GPAM or DPAM (500 mg L) was surface-applied at a rate of 30 kg ha 1 d before rainfall simulation. Rainfall was applied at 83 mm h for 50 min and then repeated for another 20 min after a 30-min rest period. Runoff samples were analyzed for volume, turbidity in nephelometric turbidity units (NTU), total suspended solids (TSS), sediment particle size distribution, and PAM concentration. The cover alone reduced turbidity and TSS in runoff by >60% compared with the control (2315 NTU, 2777 mg TSS L). The PAM further reduced turbidity and TSS by >30% regardless of the application method. The median particle diameter of eroded sediments for PAM treatments was seven to nine times that of the control (12.4 μm). Loss of applied PAM in the runoff water (not sediment) was 19% for the GPAM treatment but only 2% for the DPAM treatment. Both GPAM and DPAM were effective at improving groundcover performance, but DPAM resulted in much less PAM loss.

  6. Taxation of Controlled Foreign Companies in Context of the OECD/G20 Project on Base Erosion and Profit Shifting as well as the EU Proposal for the Anti-Tax Avoidance Directive – An Interim Nordic Assessment

    Directory of Open Access Journals (Sweden)

    Schmidt Peter Koerver

    2016-11-01

    Full Text Available Recently, the controlled foreign company (CFC rules have gained increased attention; as such, rules play an important role in the ongoing efforts of the OECD/G20 and the European Commission with respect to addressing base erosion and profit shifting (BEPS. In this context, the article revisits the CFC regimes of the Nordic countries in order to assess whether these regimes are in line with the recommendations from the OECD/G20 and to determine whether Sweden, Finland, and Denmark, as EU member states, will have to make amendments if the commission’s proposal for an Anti-Tax Avoidance Directive is adopted in its current form. It is concluded that the Nordic CFC regimes in many ways already are in line with the recommendations as well as the directive, but also that certain amendments have to be made.

  7. Tested Demonstrations.

    Science.gov (United States)

    Sands, Robert; And Others

    1982-01-01

    Procedures for two demonstrations are provided. The solubility of ammonia gas in water is demonstrated by introducing water into a closed can filled with the gas, collapsing the can. The second demonstration relates scale of standard reduction potentials to observed behavior of metals in reactions with hydrogen to produce hydrogen gas. (Author/JN)

  8. Extent of Cropland and Related Soil Erosion Risk in Rwanda

    Directory of Open Access Journals (Sweden)

    Fidele Karamage

    2016-06-01

    foster environmental sustainability or further sustainable alternative erosion control techniques may be applied, such as applying Vetiver Eco-engineering Technology due to its economical soil erosion control and stabilization of steep slopes and the construction of erosion control dams to absorb and break down excess runoff from unusually intense storms in various parts of the watersheds.

  9. EVALUATION OF TOPOGRAPHIC INDICES FOR EPHEMERAL-GULLY EROSION ASSESSMENT

    Institute of Scientific and Technical Information of China (English)

    J. CASAL(I); L. M. De SANTISTEBAN; J. J. L(O)PEZ; J. V. GIRALDEZ; J. POESEN; J. NACHTERGAELE; M. GO(N)I; J. LOIZU; M. A. CAMPO

    2005-01-01

    Soil erosion by concentrated flows in agricultural areas is an important process affecting soil losses and landscape degradation. The main factors controlling concentrated flow erosion include the erodibility of materials, soil use and management, climate, and watershed topography. In this paper,two topographic indices, closely related with mathematical expressions suggested by different authors, are used to characterize the influence of watershed topography on gully erosion. The AS1 index is defined as the product of the watershed area and the partial area-weighted average slope.The AS2 index is the product of the watershed area and the length-weighted average swale slope.Using different ephemeral gully erosion databases, a high correlation was found between the topographic indices and the volume of eroded soil. The accuracy of different methods for field measurement of ephemeral gullies was evaluated to ensure that the relation between erosion and topographic indices is not affected by assessment errors. The resulting relation are useful to assess soil losses from gully erosion, to identify the most susceptible watersheds within large areas, and to compare the susceptibility to gully erosion among different catchments. This information also can be important to study the response of natural drainage network systems to different rainfall inputs.

  10. Spatial Distribution of Soil Erosion Sensitivity on the Tibet Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Dan; ZHONG Xiang-Hao; FAN Jian-Rong

    2005-01-01

    The Tibet Plateau, occupying the main part of Qinghai-Tibet Plateau and having an average altitude of 4 500 m, has geomorphological features that are unique in the world, with soil erosion being one of the main ecological problems. Thus the main objectives of the present research were to set up an efficient and simple way of evaluating spatial distribution of soil erosion sensitivity in the Tibet Plateau as well as the responses of soil erosion to changes of natural environmental conditions, and to indicate key regions where soil erosion should be preferentially controlled. Based on the Universal Soil Loss Equation (USLE), the study applied geographic information system (GIS) technology to develop a methodological reference framework, from which soil erosion sensitivity could be evaluated. The impact of precipitation, soil, topography and vegetation on soil erosion was divided into classes of extreme sensitivity, high sensitivity, medium sensitivity, low sensitivity and no sensitivity. With the aid of GIS, the resultant map from overlaying various factors showed that soil erosion sensitivity had great discrepancy in different parts of the region. In the southeastern part of the Tibet Plateau there were mainly three classes of sensitivity, namely, extreme, high and medium sensitivity. However, the other two classes, low and no sensitivity, were dominant in the northwestern part.

  11. Multiple lines of evidence to demonstrate vinyl chloride aerobic biodegradation in the vadose zone, and factors controlling rates

    Science.gov (United States)

    Patterson, B. M.; Aravena, R.; Davis, G. B.; Furness, A. J.; Bastow, T. P.; Bouchard, D.

    2013-10-01

    A field-based investigation was conducted at a contaminated site where the vadose zone was contaminated with a range of chlorinated hydrocarbons. The investigation consisted of groundwater and multilevel soil-gas monitoring of a range of contaminants and gases, along with isotope measurements and microbiology studies. The investigation provided multiple lines of evidence that demonstrated aerobic biodegradation of vinyl chloride (VC) was occurring in the vadose zone (i) above the on-site source zone, and (ii) above the downgradient off-site groundwater plume location. Data from both the on-site and off-site locations were consistent in showing substantially greater (an order of magnitude greater) rates of VC removal from the aerobic vadose zone compared to more recalcitrant contaminants trichloroethene (TCE) and tetrachloroethene (PCE). Soil gas VC isotope analysis showed substantial isotopic enrichment of VC (δ13C - 5.2 to - 10.9‰) compared to groundwater (δ13C - 39.5‰) at the on-site location. Soil gas CO2 isotope analysis at both locations showed that CO2 was highly isotopically depleted (δ13C - 28.8 to - 33.3‰), compared to soil gas CO2 data originating from natural sediment organic matter (δ13C = - 14.7 to - 21.3‰). The soil gas CO2 δ13C values were consistent with near-water table VC groundwater δ13C values (- 36.8 to - 39.5‰), suggesting CO2 originating from aerobic biodegradation of VC. Bacteria that had functional genes (ethene monooxygenase (etnC) and epoxyalkane transferase (etnE) involved in ethene metabolism and VC oxidation were more abundant at the source zone where oxygen co-existed with VC. The distribution of VC and oxygen vadose zone vapour plumes, together with long-term changes in soil gas CO2 concentrations and temperature, provided information to elucidate the factors controlling aerobic biodegradation of VC in the vadose zone. Based on the overlapping VC and oxygen vadose zone vapour plumes, aerobic vapour biodegradation

  12. Multiple lines of evidence to demonstrate vinyl chloride aerobic biodegradation in the vadose zone, and factors controlling rates.

    Science.gov (United States)

    Patterson, B M; Aravena, R; Davis, G B; Furness, A J; Bastow, T P; Bouchard, D

    2013-10-01

    A field-based investigation was conducted at a contaminated site where the vadose zone was contaminated with a range of chlorinated hydrocarbons. The investigation consisted of groundwater and multilevel soil-gas monitoring of a range of contaminants and gases, along with isotope measurements and microbiology studies. The investigation provided multiple lines of evidence that demonstrated aerobic biodegradation of vinyl chloride (VC) was occurring in the vadose zone (i) above the on-site source zone, and (ii) above the downgradient off-site groundwater plume location. Data from both the on-site and off-site locations were consistent in showing substantially greater (an order of magnitude greater) rates of VC removal from the aerobic vadose zone compared to more recalcitrant contaminants trichloroethene (TCE) and tetrachloroethene (PCE). Soil gas VC isotope analysis showed substantial isotopic enrichment of VC (δ¹³C -5.2 to -10.9‰) compared to groundwater (δ¹³C -39.5‰) at the on-site location. Soil gas CO₂ isotope analysis at both locations showed that CO₂ was highly isotopically depleted (δ¹³C -28.8 to -33.3‰), compared to soil gas CO₂ data originating from natural sediment organic matter (δ¹³C= -14.7 to -21.3‰). The soil gas CO2 δ¹³C values were consistent with near-water table VC groundwater δ¹³C values (-36.8 to -39.5‰), suggesting CO₂ originating from aerobic biodegradation of VC. Bacteria that had functional genes (ethene monooxygenase (etnC) and epoxyalkane transferase (etnE)) involved in ethene metabolism and VC oxidation were more abundant at the source zone where oxygen co-existed with VC. The distribution of VC and oxygen vadose zone vapour plumes, together with long-term changes in soil gas CO₂ concentrations and temperature, provided information to elucidate the factors controlling aerobic biodegradation of VC in the vadose zone. Based on the overlapping VC and oxygen vadose zone vapour plumes, aerobic vapour

  13. Evaluating the efficacy of wood shreds for mitigating erosion

    Science.gov (United States)

    Randy B. Foltz; Natalie S. Copeland

    2009-01-01

    An erosion control product made by shredding on-site woody materials was evaluated for mitigating erosion through a series of rainfall simulations. Tests were conducted on bare soil and soil with 30, 50, and 70% cover on a coarse and a fine-grained soil. Results indicated that the wood product known as wood shreds reduced runoff and soil loss from both soil types....

  14. Performance Evaluation and Modeling of Erosion Resistant Turbine Engine Thermal Barrier Coatings

    Science.gov (United States)

    Miller, Robert A.; Zhu, Dongming; Kuczmarski, Maria

    2008-01-01

    The erosion resistant turbine thermal barrier coating system is critical to the rotorcraft engine performance and durability. The objective of this work was to determine erosion resistance of advanced thermal barrier coating systems under simulated engine erosion and thermal gradient environments, thus validating a new thermal barrier coating turbine blade technology for future rotorcraft applications. A high velocity burner rig based erosion test approach was established and a new series of rare earth oxide- and TiO2/Ta2O5- alloyed, ZrO2-based low conductivity thermal barrier coatings were designed and processed. The low conductivity thermal barrier coating systems demonstrated significant improvements in the erosion resistance. A comprehensive model based on accumulated strain damage low cycle fatigue is formulated for blade erosion life prediction. The work is currently aiming at the simulated engine erosion testing of advanced thermal barrier coated turbine blades to establish and validate the coating life prediction models.

  15. Effectiveness of conservation agriculture practices on soil erosion processes in semi-arid areas of Zimbabwe

    Science.gov (United States)

    Chikwari, Emmanuel; Mhaka, Luke; Gwandu, Tariro; Chipangura, Tafadzwa; Misi Manyanga, Amos; Sabastian Matsenyengwa, Nyasha; Rabesiranana, Naivo; Mabit, Lionel

    2016-04-01

    - The application of fallout radionuclides (FRNs) in soil erosion and redistribution studies has gained popularity since the late 1980s. In Zimbabwe, soil erosion research was mostly based on conventional methods which included the use of erosion plots for quantitative measurements and erosion models for predicting soil losses. Only limited investigation to explore the possibility of using Caesium-137 (Cs-137) has been reported in the early 1990s for undisturbed and cultivated lands in Zimbabwe. In this study, the Cs-137 technique was applied to assess the impact of soil conservation practices on soil losses and to develop strategies and support effective policies that help farmers in Zimbabwe for sustainable land management. The study was carried out at the Makoholi research station 30 km north of the Masvingo region which is located 260 km south of Harare. The area is semi-arid and the study site comprises coarse loamy sands, gleyic lixisols. The conservation agriculture (CA) practices used within the area since 1988 include (i) direct seeding (DS) with mulch, (ii) CA basins with mulch, and (iii) 18 years direct seeding, left fallow for seven years and turned into conventional tillage since 2012 (DS/F/C). The Cs-137 reference inventory was established at 214 ± 16 Bq/m2. The mean inventories for DS, CA basins and DS/F/C were 195, 190 and 214 Bq/m2 respectively. Using the conversion Mass Balance Model 2 on the Cs-137 data obtained along transects for each of the practices, gross erosion rates were found to be 7.5, 7.3 and 2.6 t/ha/yr for direct seeding, CA basins and the DS/F/C while the net erosion rates were found to be 3.8, 4.6 and 0 t/ha/yr respectively. Sediment delivery ratios were 50%, 63% and 2% in the respective order. These preliminary results showed the effectiveness of DS over CA basins in erosion control. The efficiency of fallowing in controlling excessive soil loss was significant in the plot that started as DS for 18 years but left fallow for 7

  16. Erosion protection benefits of stabilized SnF2 dentifrice versus an arginine-sodium monofluorophosphate dentifrice: results from in vitro and in situ clinical studies.

    Science.gov (United States)

    West, N X; He, T; Macdonald, E L; Seong, J; Hellin, N; Barker, M L; Eversole, S L

    2017-03-01

    The aim of these investigations was to assess the ability of two fluoride dentifrices to protect against the initiation and progression of dental erosion using a predictive in vitro erosion cycling model and a human in situ erosion prevention clinical trial for verification of effectiveness. A stabilized stannous fluoride (SnF2) dentifrice (0.454 % SnF2 + 0.077 % sodium fluoride [NaF]; total F = 1450 ppm F) [dentifrice A] and a sodium monofluorophosphate [SMFP]/arginine dentifrice (1.1 % SMFP + 1.5 % arginine; total F = 1450 ppm F) [dentifrice B] were tested in a 5-day in vitro erosion cycling model and a 10-day randomized, controlled, double-blind, two-treatment, four-period crossover in situ clinical trial. In each study, human enamel specimens were exposed to repetitive product treatments using a standardized dilution of test products followed by erosive acid challenges in a systematic fashion. Both studies demonstrated statistically significant differences between the two products, with dentifrice A providing significantly better enamel protection in each study. In vitro, dentifrice A provided a 75.8 % benefit over dentifrice B (p erosion. Stabilized SnF2 dentifrices may provide more significant benefits to consumers than conventional fluoride dentifrices.

  17. Simplified analytical modeling of the normal hole erosion test; Modelado analitico simplificado del ensayo normal de ersoion de tubo

    Energy Technology Data Exchange (ETDEWEB)

    Khamlichi, A.; Bezzazi, M.; El Bakkali, L.; Jabbouri, A.; Kissi, B.; Yakhlef, F.; Parron Vera, M. A.; Rubio Cintas, M. D.; Castillo Lopez, O.

    2009-07-01

    The role erosion test was developed in order to study erosion phenomenon which occurs in cracks appearing in hydraulic infrastructures such as dams. This test enables describing experimentally the erosive characteristics of soils by means of an index which is called erosion rate and a critical tension which indicates the threshold of surface erosion initiation. The objective of this work is to five modelling of this experiment by means of a simplified analytical approach. The erosion law is derived by taking into account the flow regime. This law shows that the erosion occurring in the tube is controlled by a first order dynamics where only two parameters are involved: the characteristic's time linked to the erosion rate and the stress shear threshold for which erosion begins to develop. (Author) 5 refs.

  18. Erosion response to anthropogenic activity and climatic changes during the Holocene:case studies in northwestern China and southern Norway

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Soil erosion assessment and prediction play critical roles in addressing problems associatedwith erosion control or soil conservation. The past dynamics of soil erosion can provide valuableinformation for us to understand the relations of soil erosion to environmental change andanthropogenic activity. The present paper has compared Holocene climatic changes in northwesternChina with those in southern Norway, and investigated the past dynamics of erosion activity duringthe Holocene. Modem soil erosion on the Loess Plateau is a combinafon of the intensive naturalerosion and human-induced erosion, the latter being four times greater than the former. Because ofglobal warming and increasing human activities, climate on the Loess Plateau is becoming dryer andmore unstable, causing an enhanced erosion problem and water scarcity. In the arctic-alpine region ofsouthern Norway, however, the global wanning and regional wetting caused expansion of the largestEuropean ice cap. This has accentuated the erosion in that region, with a higher frequency ofavalanches and debris flows.

  19. Erosion-resistant composite material

    Science.gov (United States)

    Finch, C.B.; Tennery, V.J.; Curlee, R.M.

    A highly erosion-resistant composite material is formed of chemical vapor-deposited titanium diboride on a sintered titanium diboride-nickel substrate. This material may be suitable for use in cutting tools, coal liquefaction systems, etc.

  20. Field measurement of basal forces generated by erosive debris flows

    Science.gov (United States)

    McCoy, S.W.; Tucker, G.E.; Kean, J.W.; Coe, J.A.

    2013-01-01

    differences in appearance and bulk‒flow density. These results demonstrate that debris flows can have strong control on rates of steepland evolution and contribute to a foundation needed for modeling debris‒flow incision stochastically.

  1. [Gastric band erosion: Alternative management].

    Science.gov (United States)

    Echaverry-Navarrete, Denis José; Maldonado-Vázquez, Angélica; Cortes-Romano, Pablo; Cabrera-Jardines, Ricardo; Mondragón-Pinzón, Erwin Eduardo; Castillo-González, Federico Armando

    2015-01-01

    Obesity is a public health problem, for which the prevalence has increased worldwide at an alarming rate, affecting 1.7 billion people in the world. To describe the technique employed in incomplete penetration of gastric band where endoscopic management and/or primary closure is not feasible. Laparoscopic removal of gastric band was performed in five patients with incomplete penetrance using Foley catheterization in the perforation site that could lead to the development of a gastro-cutaneous fistula. The cases presented include a leak that required surgical lavage with satisfactory outcome, and one patient developed stenosis 3 years after surgical management, which was resolved endoscopically. In all cases, the penetration site closed spontaneously. Gastric band erosion has been reported in 3.4% of cases. The reason for inserting a catheter is to create a controlled gastro-cutaneous fistula, allowing spontaneous closure. Various techniques have been described: the totally endoscopic, hybrid techniques (endoscopic/laparoscopic) and completely laparoscopic. A technique is described here that is useful and successful in cases where the above-described treatments are not viable. Copyright © 2015. Published by Masson Doyma México S.A.

  2. Tested Demonstrations.

    Science.gov (United States)

    Gilbert, George L., Ed.

    1983-01-01

    Free radical chlorination of methane is used in organic chemistry to introduce free radical/chain reactions. In spite of its common occurrence, demonstrations of the reaction are uncommon. Therefore, such a demonstration is provided, including background information, preparation of reactants/reaction vessel, introduction of reactants, irradiation,…

  3. Tested Demonstrations.

    Science.gov (United States)

    Gilbert, George L., Ed.

    1983-01-01

    Discusses a supplement to the "water to rose" demonstration in which a pink color is produced. Also discusses blood buffer demonstrations, including hydrolysis of sodium bicarbonate, simulated blood buffer, metabolic acidosis, natural compensation of metabolic acidosis, metabolic alkalosis, acidosis treatment, and alkalosis treatment. Procedures…

  4. Complete Demonstration.

    Science.gov (United States)

    Yelon, Stephen; Maddocks, Peg

    1986-01-01

    Describes four-step approach to educational demonstration: tell learners they will have to perform; what they should notice; describe each step before doing it; and require memorization of steps. Examples illustrate use of this process to demonstrate a general mental strategy, and industrial design, supervisory, fine motor, and specific…

  5. Tested Demonstrations.

    Science.gov (United States)

    Gilbert, George L., Ed.

    1987-01-01

    Describes two laboratory demonstrations in chemistry. One uses dry ice, freon, and freezer bags to demonstrate volume changes, vapor-liquid equilibrium, a simulation of a rain forest, and vaporization. The other uses the clock reaction technique to illustrate fast reactions and kinetic problems in releasing carbon dioxide during respiration. (TW)

  6. Tested Demonstrations.

    Science.gov (United States)

    Gilbert, George L., Ed.

    1986-01-01

    Outlines a simple, inexpensive way of demonstrating electroplating using the reaction between nickel ions and copper metal. Explains how to conduct a demonstration of the electrolysis of water by using a colored Na2SO4 solution as the electrolyte so that students can observe the pH changes. (TW)

  7. Wind erosion of soils burned by wildfire

    Science.gov (United States)

    N. S. Wagenbrenner; M. J. Germino; B. K. Lamb; R. B. Foltz; P. R. Robichaud

    2011-01-01

    Wind erosion and aeolian transport processes are largely unstudied in the post-wildfire environment, but recent studies have shown that wind erosion can play a major role in burned landscapes. A wind erosion monitoring system was installed immediately following a wildfire in southeastern Idaho, USA to measure wind erosion from the burned area (Figure 1). This paper...

  8. Soil erosion in developing countries: A politicoeconomic explanation

    Science.gov (United States)

    Thapa, Gopal B.; Weber, Karl E.

    1991-07-01

    Soil erosion is accelerating in developing countries of Asia, Africa, and Latin America. It has threatened the livelihood of millions of peasants, for agriculture is their economic mainstay. A probe into the forces causing erosion reveals that the elite’s resolve to accumulate ever more wealth and to maintain, consolidate, or expand their sociopolitical power and the necessity of the poor to fulfill their requirements of food, fuelwood, and fodder are the two major factors accelerating soil erosion. Unless the vast masses of poor people are integrated into the national mainstream through the implementation of equitable and redistributive development policies, it is impossible to control the accelerating rate of soil erosion and thus to achieve the objective of sustainable development.

  9. An holistic approach to beach erosion vulnerability assessment.

    Science.gov (United States)

    Alexandrakis, George; Poulos, Serafim Ε

    2014-08-15

    Erosion is a major threat for coasts worldwide, beaches in particular, which constitute one of the most valuable coastal landforms. Vulnerability assessments related to beach erosion may contribute to planning measures to counteract erosion by identifying, quantifying and ranking vulnerability. Herein, we present a new index, the Beach Vulnerability Index (BVI), which combines simplicity in calculations, easily obtainable data and low processing capacity. This approach provides results not only for different beaches, but also for different sectors of the same beach and enables the identification of the relative significance of the processes involved. It functions through the numerical approximation of indicators that correspond to the mechanisms related to the processes that control beach evolution, such as sediment availability, wave climate, beach morhodynamics and sea level change. The BVI is also intended to be used as a managerial tool for beach sustainability, including resilience to climate change impact on beach erosion.

  10. The plot size effect on soil erosion on rainfed agriculture land under different land uses in eastern Spain

    Science.gov (United States)

    Cerdà, A.; Bodí, M. B.; Burguet, M.; Segura, M.; Jovani, C.

    2009-04-01

    Soil erosion at slope scale is dependent on the size of the plot. This is because soil erosion is a scale-dependent process due to the spatial variability in infiltration, the potential for sediment to be captured by vegetation and other roughness components, and the changes in erosion rates and processes with increasing amounts of runoff. The effects of plot size may also vary with land use, as plot size may be less important in areas with a more homogeneous plant cover or bares soils; meanwhile the soil transmission losses will higher on vegetation covered soils and on patchy distributed plants. A series of study plots were established in 2003 at the El Teularet experimental Station in the Sierra de Enguera in eastern Spain. The overall goal is to assess runoff and erosion rates from different land uses at different spatial scales. Thirteen sets of plots have been established, and each set consists of five adjacent plots that vary in size from 1 m2 (1 x 1 m), 2 m2 (1 x 2 m), 4 m2 (1 x 4 m), 16 m2 (2 x 8 m) and 48 m2 (3 m wide x 16 m length). Each set of plots has a different land use, and the land uses being tested in the first year of this study are fallow, ploughed but unplanted, untilled oats and beans, tilled oats and beans, straw mulch, mulched with chipped olive branches, a geotextile developed to control erosion on agricultural fields, scrub oaks (Quercus coccifera), gorse (Ulex parviflorus), and three herbicide treatments—a systemic herbicide, a contact herbicide, and a persistent herbicide. From those plots, three plots were selected to analyse the effect of the size of the plot on the soil erosion assessment. Herbicide (bare), Catch crops (oat) and scrubland were selected to analyze the soil losses during 2004 and 2005. The results shows that sediment delivery is highly dependent on the land use and land management as the scrubland contributed with null sediment yield, meanwhile the herbicide reached the largest soil loss. The soil erosion was higher

  11. Tested Demonstrations.

    Science.gov (United States)

    Gilbert, George L.

    1990-01-01

    Included are three demonstrations that include the phase change of ice when under pressure, viscoelasticity and colloid systems, and flame tests for metal ions. The materials, procedures, probable results, and applications to real life situations are included. (KR)

  12. Tested Demonstrations.

    Science.gov (United States)

    Gilbert, George L., Ed.

    1980-01-01

    Presented is a Corridor Demonstration which can be set up in readily accessible areas such as hallways or lobbies. Equipment is listed for a display of three cells (solar cells, fuel cells, and storage cells) which develop electrical energy. (CS)

  13. Tested Demonstrations.

    Science.gov (United States)

    Gilbert, George L., Ed.

    1987-01-01

    Presents three demonstrations suitable for undergraduate chemistry classes. Focuses on experiments with calcium carbide, the induction by iron of the oxidation of iodide by dichromate, and the classical iodine clock reaction. (ML)

  14. Tolerable soil erosion in Europe

    Science.gov (United States)

    Verheijen, Frank; Jones, Bob; Rickson, Jane; Smith, Celina

    2010-05-01

    Soil loss by erosion has been identified as an important threat to soils in Europe* and is recognised as a contributing process to soil degradation and associated deterioration, or loss, of soil functioning. From a policy perspective, it is imperative to establish well-defined baseline values to evaluate soil erosion monitoring data against. For this purpose, accurate baseline values - i.e. tolerable soil loss - need to be differentiated at appropriate scales for monitoring and, ideally, should take soil functions and even changing environmental conditions into account. The concept of tolerable soil erosion has been interpreted in the scientific literature in two ways: i) maintaining the dynamic equilibrium of soil quantity, and ii) maintaining biomass production, at a location. The first interpretation ignores soil quality by focusing only on soil quantity. The second approach ignores many soil functions by focusing only on the biomass (particularly crop) production function of soil. Considering recognised soil functions, tolerable soil erosion may be defined as 'any mean annual cumulative (all erosion types combined) soil erosion rate at which a deterioration or loss of one or more soil functions does not occur'. Assumptions and problems of this definition will be discussed. Soil functions can generally be judged not to deteriorate as long as soil erosion does not exceed soil formation. At present, this assumption remains largely untested, but applying the precautionary principle appears to be a reasonable starting point. Considering soil formation rates by both weathering and dust deposition, it is estimated that for the majority of soil forming factors in most European situations, soil formation rates probably range from ca. 0.3 - 1.4 t ha-1 yr-1. Although the current agreement on these values seems relatively strong, how the variation within the range is spatially distributed across Europe and how this may be affected by climate, land use and land management

  15. 汽轮机低压调节级动叶片水蚀分析%Analysis on Water - Erosion of Moving Blade in Low - pressure Control Stage of a Steam Turbine

    Institute of Scientific and Technical Information of China (English)

    周文远; 朱正写; 王鹏; 纪绣涛

    2012-01-01

    烯烃装置裂解气压缩机组大检修期间发现汽轮机低压调节级动叶片“蜂窝状点蚀”现象比较严重,对应的静叶片及后2级静叶片也有点蚀现象。分析发现利用湿蒸汽对汽轮机吹扫的方法存在缺陷,在主蒸汽降温的过程中只考虑了高压缸防水蚀的影响,忽略了抽汽背压不可控,导致低压缸进汽压力相对该处的进汽温度过高,部分蒸汽产生冷凝液,蒸汽中夹带的水滴撞击在动叶片出汽边背弧上,致使材料疲劳破坏形成水蚀。根据操作经验和理论分析确定:吹扫工况时,低压调节级的进汽压力应低于170℃时的蒸汽饱和压力,抽汽压力应低于0.8MPa,并利用蒸汽管网改造,控制抽汽压力在0.4~1.6MPa。通过优化操作参数完全可以避免低压调节级动叶片水蚀。%Serious "honeycomb pitting corrosions" were found in the moving blades of the steam turbine's low -pressure control stage in the overhaul of the cracked gas compressor train, corresponding stationary blades and after the two - stage stationary blades also had "pitting corrosion". The analysis concluded that there was negligence in the flushing of steam turbine with wet steam. In the process of lowering the steam temperature, only the impact of water erosion of HP cylinder was considered and uncontrollable extracted steam pressure was ignored. These led to excessive higher temperature of inlet steam as compared with the pressure. Condensate was formed from some steam, water droplets entrained in the steam impinged on the back arc of the moving blades, the material was fatigued and water erosion was formed. Based upon the operating experience and theoretical analysis, in flushing operation, the pressure of inlet steam of LP control stage should be lower than steam saturation steam at 170℃, and the pressure of extracted steam should be lower than 0.8 MPa. The pressure of extracted steam was controlled within 0. 4 1

  16. The Erosive Effects of Racism: Reduced Self-control Mediates the Relation between Perceived Racial Discrimination and Substance Use in African American Adolescents

    Science.gov (United States)

    Gibbons, Frederick X.; O'Hara, Ross E.; Stock, Michelle L.; Gerrard, Meg; Weng, Chih-Yuan; Wills, Thomas A.

    2012-01-01

    Perceived racial discrimination, self-control, anger, and either substance use or use cognitions were assessed in two studies conducted with samples of African American adolescents. The primary goal was to examine the relation between discrimination and self-control over time; a second goal was to determine if that relation mediates the link between discrimination and substance use found in previous research. Study 1, which included a latent growth curve analysis with three waves of data, indicated that experience with discrimination (from age 10 to age 18) was associated with reduced self-control, which then predicted increased substance use. Additional analyses indicated anger was also a mediator of this discrimination to use relation. Study 2, which was experimental, showed that envisioning an experience involving discrimination was associated with an increase in substance-related responses to double entendre words (e.g., “pot,” “roach”) in a word association task, especially for participants who were low in dispositional self-control. The effect was again mediated by reports of anger. Thus, the “double mediation” pattern was: discrimination → more anger and reduced self-control → increased substance use and/or substance cognitions. Results are discussed in terms of the long-term impact of discrimination on self-control and health behavior. Implications for interventions aimed at ameliorating the negative effects of discrimination and low self-control on health are also discussed. PMID:22390225

  17. Science You Can Use Bulletin: From watersheds to the web: Online tools for modeling forest soil erosion

    Science.gov (United States)

    Sue Miller; Bill Elliot; Pete Robichaud; Randy Foltz; Dennis Flanagan; Erin Brooks

    2014-01-01

    Forest erosion can lead to topsoil loss, and also to damaging deposits of sediment in aquatic ecosystems. For this reason, forest managers must be able to estimate the erosion potential of both planned management activities and catastrophic events, in order to decide where to use limited funds to focus erosion control efforts. To meet this need, scientists from RMRS (...

  18. Influence of drinking patterns of carbonated beverages on dental erosion.

    Science.gov (United States)

    Bassiouny, Mohamed A; Yang, Jie

    2005-01-01

    As a hard tissue dental disease, dental erosion has a multifactorial etiology. The majority of dental erosion that originates from extrinsic sources is the result of dietary intake, particularly acidic beverages. Several preventive means have been proposed to minimize the damage to the dentition, including a reduction in the consumption of causative beverages and the adoption of a specific method of drinking, utilizing a straw instead of a cup. This article presents two cases involving the clinical and radiographic features of erosion lesions associated with chronic and excessive intake of acidic carbonated beverages. These examples embody how drinking patterns influence the formation of erosion lesions in various anatomic locations within the dentition. The clinical and radiographic evidence presented in this report cautions against the use of nonspecific terms, such as "cup versus straw," and instead suggests implementing a more precise description of the suggested method. In view of the extensive damage inflicted by the chronic, excessive intake of carbonated beverages, preventive measures are considered to be the only effective course of management. This article offers illustrative examples of erosion lesions associated with long-term excessive intake of carbonated beverages. The influence of the drinking method--that is, a straw positioned into the labial vestibule versus a cup--on the anatomic location of the erosion lesions will be demonstrated through clinical and radiographic evidence.

  19. Tested Demonstrations.

    Science.gov (United States)

    Gilbert, George L., Ed.

    1987-01-01

    Describes two demonstrations to illustrate characteristics of substances. Outlines a method to detect the changes in pH levels during the electrolysis of water. Uses water pistols, one filled with methane gas and the other filled with water, to illustrate the differences in these two substances. (TW)

  20. ICT Demonstration

    DEFF Research Database (Denmark)

    Jensen, Tine Wirenfeldt; Bay, Gina

    In this demonstration we present and discuss two interrelated on-line learning resources aimed at supporting international students at Danish universities in building study skills (the Study Metro) and avoiding plagiarism (Stopplagiarism). We emphasize the necessity of designing online learning r...

  1. Bentonite erosion. Laboratory studies

    Energy Technology Data Exchange (ETDEWEB)

    Jansson, Mats (Div. of Nuclear Chemistry, Royal Inst. of Technology, Stockholm (Sweden), School of Chemical Science and Engineering)

    2009-11-15

    This report covers the laboratory studies that have been performed at Nuclear Chemistry, KTH in the project 'Bentonite Erosion'. Many of the experiments in this report were performed to support the work of the modelling group and were often relatively simple. One of the experiment series was performed to see the impact of gravity and concentration of mono- and di-valent cations. A clay suspension was prepared in a test tube. A net was placed in contact with the suspension, the test tube was filled with solutions of different concentrations and the system was left overnight to settle. The tube was then turned upside down and the behaviour was visually observed. Either the clay suspension fell through the net or stayed on top. By using this method surprisingly sharp determinations of the Critical Coagulation (Flocculation) Concentration (CCC/CFC) could be made. The CCC/CFC of Ca2+ was for sodium montmorillonite determined to be between 1 and 2 mM. An artificial fracture was manufactured in order to simulate the real case scenario. The set-up was two Plexiglas slabs separated by 1 mm thick spacers with a bentonite container at one side of the fracture. Water was pumped with a very low flow rate perpendicular to bentonite container and the water exiting the fracture was sampled and analyzed for colloid content. The bentonite used was treated in different ways. In the first experiment a relatively montmorillonite rich clay was used while in the second bentonite where only the readily soluble minerals had been removed was used. Since Plexiglas was used it was possible to visually observe the bentonite dispersing into the fracture. After the compacted bentonite (1,000 kg/m3) had been water saturated the clay had expanded some 12 mm out into the fracture. As the experiment progressed the clay expanded more out into the fracture and seemed to fractionate in two different phases with less material in the outmost phase. A dark rim which was later analyzed to contain

  2. Rill Erosion in Post Wildfire Forests after Salvage Logging

    Science.gov (United States)

    Robichaud, Peter; Wagenbrenner, Joseph; Brown, Robert

    2016-04-01

    Despite the dominance of concentrated flow or rill erosion in the erosion processes especially in steep forest environments that have been affected by wildfire or management activities few studies have quantified these effects on rill erosion. This study quantified the effects of wildfire and post-fire timber salvage operations on rill runoff quantity, runoff velocity, and rill erosion. Simulated rill experiments were conducted at various sites in the Western US after wildfire and timber salvage operations. The onsite conditions consists of burned only, salvage logged, skid or snig trail, or skid trails with extra logging debris added. For each rill experiment, concentrated flow was applied at the top of the plot through an energy dissipater at five inflow rates for 12 min each. Runoff was sampled every 2 min and runoff volume and sediment concentration were determined for each sample. The runoff velocity was measured using a dyed calcium chloride solution and two conductivity probes placed a known distance apart. Runoff volume, runoff velocities, and sediment concentrations increased with increasing levels of disturbance. The burned only plots had lower runoff rates and sediment concentrations than any of the other disturbances. The salvage logged plots had greater responses than the burn only plots and the mitigation treatment had a marginal effect on runoff ratios, runoff velocities and sediment concentrations. These results suggest that additional disturbance after a wildfire can increase the erosional response and that proper erosion control mitigation may be an important consideration for post fire management to reduce onsite erosion.

  3. Exploring the relationship between gully erosion and rainfall erosivity

    Science.gov (United States)

    Campo, Miguel; Casalí, Javier; Giménez, Rafael

    2016-04-01

    Rainfall erosivity plays and important role in gully erosion. However, there are few studies that explore this relationship. The main purpose of this work is to analyse the link between observed gully erosion rates and rainfall erosivity. However, in order to get a suitable and comparable set of daily rainfall erosivity data, we firstly evaluate the performance of several daily rainfall erosivity models to estimate the daily accumulated RUSLE EI30 index. One 300 ha watershed (El Cantalar) located in Navarre (Spain) was selected to carry out field studies. A meteorological station located 10 km appart from the experimental site provided daily precipitation records since 1930 to 2009 and also 10min records since 1991 to 2009. In this watershed a total of 35 gully headcuts developed in cohesive soil were monitored. Aerial photographic stereo-pairs covering the study area were used for the survey. These were taken in five different years and at different spatial scales each time: 1956 (1: 34,000), 1967 (1:17,500), 1982 (1:13,500), 2003 (1:20,000) and 2006 (1:2000). Manual restitution of photographs was carried out. 1m resolution DEMs were obtained by triangular interpolation (Triangular Irregular Network) and then used to characterize gully headcuts. Moreover, from the aerial photos and the DEMs, ortho-photographs with a final resolution of 0.40 m were created. The geocoding of the scenes had a Root Mean Square error of less than 0.5 m both in planimetry and altimetry. Furthermore, using the DEMs and the ortho-photographs, volumetric headcut retreat rates for each period were calculated as the product of the lineal retreat and a representative section of the headcut. Daily accumulated RUSLE EI30 index was calculated in a conventional way from records of precipitation every 10 minutes for the period 1991-2009; these results were used as reference data. In addition, for the same period, this index was estimated with daily precipitation records through several models

  4. Environmental Factors Affecting Temporal and Spatial Dynamics of Soil Erosion in Xingguo County, South China

    Institute of Scientific and Technical Information of China (English)

    WANG Ku; SHI Xue-Zheng; YU Dong-Sheng; SHI De-Ming; CHEN Jing-Ming; XU Bin-Bin; LIANG Yin; LI De-Cheng

    2005-01-01

    By using soil erosion maps of four different time periods and a digital elevation model (DEM), in combination with the remote sensing and GIS technologies, soil erosion dynamics in Xingguo County of Jiangxi Province in South China were analyzed on both temporal and spatial scales in soils of different parent materials, altitudes and slopes. The results showed that from 1958 to 2000 severe soil erosion was coming under control with a decreasing percentage of the land under severe erosion. It was also found that the soils developed from Quaternary red clay, granite and purple shale were more susceptible to soil erosion and that areas sitting between 200 to 500 m in altitude with a slope less than 3° or between 7° to 20° where human activities were frequent remained to be zones where soil erosion was most likely to occur. These areas deserve special attention in monitoring and controlling.

  5. Interfacial Instability during Granular Erosion.

    Science.gov (United States)

    Lefebvre, Gautier; Merceron, Aymeric; Jop, Pierre

    2016-02-12

    The complex interplay between the topography and the erosion and deposition phenomena is a key feature to model granular flows such as landslides. Here, we investigated the instability that develops during the erosion of a wet granular pile by a dry dense granular flow. The morphology and the propagation of the generated steps are analyzed in relation to the specific erosion mechanism. The selected flowing angle of the confined flow on a dry heap appears to play an important role both in the final state of the experiment, and for the shape of the structures. We show that the development of the instability is governed by the inertia of the flow through the Froude number. We model this instability and predict growth rates that are in agreement with the experiment results.

  6. Best Demonstrated Available Technology (BDAT) for pollution control and waste treatment. (Latest citations from the NTIS bibliographic database). Published Search

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-10-01

    The bibliography contains citations concerning the most advanced equipment and processes for pollution control and waste treatment according to the guidelines set by the Environmental Protection Agency (EPA). Citations discuss biological, thermal, physical, and chemical prosesses for the technology innovation, economic productivity, and environmental protection. Standards and regulations for gaseous, liquid, and solid pollution are included. Also discussed are water pollution control, food and pharmaceutical wastes, effluent treatment, and materials recovery. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  7. Soil erosion in Slovene Istria

    Directory of Open Access Journals (Sweden)

    Matjaž Mikoš

    2009-12-01

    Full Text Available From the end of nineties of the 20th century, intense hydrologic and geomorphologic research is taking place in the Slovene Istria. As a part of this research also studies on soil erosion were undertaken in the period from 2005 to 2008. The field measurements were under taken onclosed 1m2 large erosion plots under three different land uses (on bare soils in an olive grove, on an overgrown meadow, in a forest, placed south of the Marezige village in the Rokava River basin.We show weekly measurements of surface erosion (interrill erosion for the period of 13 months (the end of March 2005 – the end of April 2006, as well as monthly and seasonal averages together with selected linear statistical correlations between soil erosion and weather parameters.From May 2005 to April 2006 the interrill erosion on bare soils in an olive grove with an inclination of 5.5° amounted to 9013 g/m2 (90 t/ha that corresponds to surface lowering rate of 8.5 mm/yr; on an overgrown meadow with an inclination of 9.4° it amounted to 168 g/m2 (1,68 t/ha that corresponds to surface lowering rate of 0.16 mm//yr; and in a forest with an inclination of 7.8° it amounted to 391 g/m2 (3,91 t/ha and in a forest with an inclination of 21.4° it amounted to 415 g/m2 (4,15 t/ha, respectively, that corresponds to surface lowering rate of 0.4 mm/yr.

  8. Demonstrator Flood Control Room : Inventarisatie van de wensen van de verschillende Deltares onderdelen en een hierop gebaseerd ontwerp

    NARCIS (Netherlands)

    Boertjens, G.J.; Attema-van Waas, A.R.; Guikema, M.; Schilder, C.M.C.; Veen, M.J. van der

    2009-01-01

    Op basis van het uitgevoerde onderzoek trekt TNO de volgende conclusies: • De bestaande ruimte die Deltares op het oog heeft voor de realisatie van de trainingsruimte is klein. Een eerste fase van de gewenste Flood Control Room is realiseerbaar in deze ruimte, met inachtneming dat niet alle geïdenti

  9. Grout disposal facility vault exhauster: Technical background document on demonstration of best available control technology for toxics

    Energy Technology Data Exchange (ETDEWEB)

    Glissmeyer, J.A.; Glantz, C.S. [Pacific Northwest Lab., Richland, WA (United States); Rittman, P.D. [Westinghouse Hanford Co., Richland, WA (United States)

    1994-09-01

    The Grout Disposal Facility (GDF) is currently operated on the US Department of Energy`s Hanford Site. The GDF is located near the east end of the Hanford Site`s 200 East operations area, and is used for the treatment and disposal of low-level radioactive liquid wastes. In the grout treatment process, selected radioactive wastes from double-shell tanks are mixed with grout-forming solids; the resulting grout slurry is pumped to near-surface concrete vaults for solidification and permanent disposal. As part of this treatment process, small amounts of toxic particles and volatile organic compounds (VOCs) may be released to the atmosphere through the GDF`s exhaust system. This analysis constitutes a Best Available Control Technology for Toxics (T-BACT) study, as required in the Washington Administrative Code (WAC 173-460) to support a Notice of Construction for the operation of the GDF exhaust system at a modified flow rate that exceeds the previously permitted value. This report accomplishes the following: assesses the potential emissions from the GDF; estimates air quality impacts to the public from toxic air pollutants; identifies control technologies that could reduce GDF emissions; evaluates impacts of the control technologies; and recommends appropriate emissions controls.

  10. PILOT-AND FULL-SCALE DEMONSTRATION OF ADVANCED MERCURY CONTROL TECHNOLOGIES FOR LIGNITE-FIRED POWER PLANTS

    Energy Technology Data Exchange (ETDEWEB)

    Steven A. Benson; Charlene R. Crocker; Kevin C. Galbreath; Jay R. Gunderson; Michael J. Holmes; Jason D. Laumb; Jill M. Mackenzie; Michelle R. Olderbak; John H. Pavlish; Li Yan; Ye Zhuang

    2005-02-01

    The overall objective of the project was to develop advanced innovative mercury control technologies to reduce mercury emissions by 50%-90% in flue gases typically found in North Dakota lignite-fired power plants at costs from one-half to three-quarters of current estimated costs. Power plants firing North Dakota lignite produce flue gases that contain >85% elemental mercury, which is difficult to collect. The specific objectives were focused on determining the feasibility of the following technologies: Hg oxidation for increased Hg capture in dry scrubbers, incorporation of additives and technologies that enhance Hg sorbent effectiveness in electrostatic precipitators (ESPs) and baghouses, the use of amended silicates in lignite-derived flue gases for Hg capture, and the use of Hg adsorbents within a baghouse. The approach to developing Hg control technologies for North Dakota lignites involved examining the feasibility of the following technologies: Hg capture upstream of an ESP using sorbent enhancement, Hg oxidation and control using dry scrubbers, enhanced oxidation at a full-scale power plant using tire-derived fuel and oxidizing catalysts, and testing of Hg control technologies in the Advanced Hybrid{trademark} filter.

  11. Mechatronic Aeropendulum: Demonstration of Linear and Nonlinear Feedback Control Principles with MATLAB/Simulink Real-Time Windows Target

    Science.gov (United States)

    Enikov, E. T.; Campa, G.

    2012-01-01

    This paper presents a low-cost hands-on experiment for a classical undergraduate controls course for non-electrical engineering majors. The setup consists of a small dc electrical motor attached to one of the ends of a light rod. The motor drives a 2-in propeller and allows the rod to swing. Angular position is measured by a potentiometer attached…

  12. Experimental demonstration of a new model-based SCR control strategy for cleaner heavy-duty diesel engines

    NARCIS (Netherlands)

    Willems, F.P.T.; Cloudt, R.P.M.

    2011-01-01

    Selective catalytic reduction (SCR) is a promising diesel aftertreatment technology that enables low nitrogen oxides (NOx) tailpipe emissions with relatively low fuel consumption. Future emission legislation is pushing the boundaries for SCR control systems to achieve high NOx conversion within a ta

  13. Mechatronic Aeropendulum: Demonstration of Linear and Nonlinear Feedback Control Principles with MATLAB/Simulink Real-Time Windows Target

    Science.gov (United States)

    Enikov, E. T.; Campa, G.

    2012-01-01

    This paper presents a low-cost hands-on experiment for a classical undergraduate controls course for non-electrical engineering majors. The setup consists of a small dc electrical motor attached to one of the ends of a light rod. The motor drives a 2-in propeller and allows the rod to swing. Angular position is measured by a potentiometer attached…

  14. Experimental demonstration of a new model-based SCR control strategy for cleaner heavy-duty diesel engines

    NARCIS (Netherlands)

    Willems, F.P.T.; Cloudt, R.P.M.

    2011-01-01

    Selective catalytic reduction (SCR) is a promising diesel aftertreatment technology that enables low nitrogen oxides (NOx) tailpipe emissions with relatively low fuel consumption. Future emission legislation is pushing the boundaries for SCR control systems to achieve high NOx conversion within a

  15. Controlled challenge experiment demonstrates substantial additive genetic variation in resistance of Nile tilapia (Oreochromis niloticus) to Streptococcus iniae

    Science.gov (United States)

    Streptococcus iniae is an etiologic agent of streptococcal disease in tilapia and is one of several Streptococcus spp. that negatively impact worldwide tilapia production. Methods for the prevention and control of S. iniae include vaccines, management strategies, and antibiotics. A complimentary pre...

  16. 搭设障蔽控制樟子松风蚀沙埋危害的效果%Control Effect on Wind Erosion and Sand Cover by Building Sand-Barrier for Pinus sylvestris var.mongolica Plantation

    Institute of Scientific and Technical Information of China (English)

    屈升银; 叶竹林

    2011-01-01

    The control effect on wind erosion and sand cover by building sand-barrier was studied by taking Pinus sylvestris var. Mongolica as planting tree species. The results showed that building sand-barrier could promote the survival rate of the plantation up to 100% , which was significantly higher than that of the control. There were also significant differences in the growth rate of the Pinus sylvestris var. Mongolica plantation between building the sand-barrier and the control. The experiment showed that building the sand-barrier could promote the average sapling height, basal diameter and crown growth by 55.4% , 66. 6% and 60.1% respectively compared to the control. Sand-barrier building provided the morphology construction of the Pinus sylvestris var. Mongolica saplings with much better environment that significantly reduced the phenomena such as trunk bending, wind throw and drying up of the brnaches and turning yellow of the leaves due to the wind damage.%以樟子松为对象探讨搭设沙障控制风蚀沙埋危害的效果.结果表明:搭设与未搭设沙障的造林保存率存在显著差异,搭设沙障可使造林保存率高达100%;搭设与未搭设沙障的生长量也存在显著差异,搭设沙障可使树高、地径、树冠生长量分别提高55.4%、66.6%和60.7%;搭设沙障为樟子松的形态建成创造了良好的环境条件,树干弯曲、风倒及枯黄现象明显减少.

  17. Modeling the Erosion Process in Beaded Streams in a Semi-arid Bajada, Southern New Mexico

    Science.gov (United States)

    Gao, P.

    2003-12-01

    A channel network in Southern New Mexico falls in one of the three categories: splay, bead, and braid. A splay simply refers to diverging channels. A bead refers to channel reaches in which flow first diverges to form an area of multiple flow paths and then converges to form a single channel. A braid is intermediate between a splay and a bead. Recent studies have demonstrated that beads, which widely exist in the semi-arid environment of Southern New Mexico, serve as sinks to attract more water, nutrients, and sediment than other areas. Thus beads provide a physical base for ecological remediation means to reverse the desertification process. However, the mechanisms for the formation of a bead and geomorphologic factors controlling the properties of a bead are still poorly understood. Given the difficulties of physically tracking and quantitatively estimating the development of a bead in the field, a computer simulation is adopted to model the erosion process that leads to the beaded streams. The modeling is based on a FORTRAN algorithm in which the bajada surface is represented by a matrix of square cells. On each cell, both sediment transport and continuity equations, which are sufficient to describe the erosion process, are applied to determine whether the cell is degraded (erosion), aggraded (deposition), or graded (equilibrium). With a rule of determining the distribution of flow rate from a cell to its downstream neighbors, channels are automatically formed by the erosion processes. The simulation indicates (1) that a bead is formed with the combination of three factors: uneven distribution of flow rate, infiltration, and the degree of distribution, (2) that a bead, once formed, is stable, (3) that the size and shape of a bead are controlled by the discharge-infiltration ratio.

  18. Extracting change information of land-use and soil-erosion based on RS & GIS technology

    Institute of Scientific and Technical Information of China (English)

    LI Zhong-feng; LI You-cai

    2007-01-01

    Rapid land-use change has taken place in many arid regions of China such as Yulin prefecture over the last decade due to rehabilitation measures. Land-use change and soil erosion dynamics were investigated by the combined use of remote sensing and geographic information systems (GIS). The objectives were to determine land-use transition rates and soil erosion change in Yulin prefecture over 15 years from 1986 to 2000. Significant changes in land-use and soil erosion occurred in the area over the study period. The results show the significant decrease in barren land mainly due to conversion to grassland. Agricultural land increased associated with conversions from grassland and barren land. The area of water erosion and wind erosion declined. The study demonstrates that the integration of satellite remote sensing and GIS is an effective approach for analyzing the direction, rate, and spatial pattern of land-use and soil erosion change.

  19. Note: A concrete erosion sensor based on a chirped fibre optic Bragg grating.

    Science.gov (United States)

    Kanopoulos, Patrick; Xia, Kaiwen; Gu, Xijia; Amirchoupani, Ardavan; Yao, Wei

    2015-12-01

    Erosion of concrete surfaces in major civil structures is a common problem, which in certain circumstances can undermine the structural and operational integrities of the structure. The manual monitoring of the erosion process can be difficult and dangerous under certain circumstances (such as within hydrotunnels and spillways of dams). This paper describes a concrete erosion sensor based on a chirped fibre Bragg grating (FBG) which is able to monitor the extent of concrete erosion at a single point to sub-millimetre accuracy. The chirped FBG length embedded below the concrete surface decreases as a result of concrete erosion and consequently the reflected light spectrum bandwidth narrows. A simple procedure is presented to determine the extent of erosion, and this procedure is applied to an experimental demonstration of the sensing device.

  20. Efficient synthesis of mosquitocidal toxins in Asticcacaulis excentricus demonstrates potential of gram-negative bacteria in mosquito control.

    Science.gov (United States)

    Liu, J W; Yap, W H; Thanabalu, T; Porter, A G

    1996-03-01

    The control of mosquitoes with chemical insecticides pollutes the environment and leads to resistance in mosquito populations. Bacterial control of mosquito larvae with Bacillus sphaericus and Bacillus thuringiensis subsp. israelensis, which produce protein toxins, has proved useful, safe, and nonpolluting. These bacteria do, however, suffer from disadvantages, including rapid setting, UV sensitivity, and lack of persistance of spores, proteolysis of toxins, narrow host range, and high production costs. Here we show that the Gram-negative bacterium Asticcacaulis excentricus is a promising host for delivering toxins to mosquito larvae. Plasmid-transformed A. excentricus cells expressing the binary toxin of B. sphaericus exhibited toxicity to Culex and Anopheles mosquito larvae similar to that of the high-toxicity strains of B. sphaericus which produce several toxins. A. excentricus has potential advantages as a larvicide compared with the bacilli, especially persistance in the larval feeding zone, resistance to UV light, lack of toxin-degrading proteases, and low production costs.

  1. Field methods for measuring concentrated flow erosion

    Science.gov (United States)

    Castillo, C.; Pérez, R.; James, M. R.; Quinton, J. N.; Taguas, E. V.; Gómez, J. A.

    2012-04-01

    techniques (3D) for measuring erosion from concentrated flow (pole, laser profilemeter, photo-reconstruction and terrestrial LiDAR) The comparison between two- and three-dimensional methods has showed the superiority of the 3D techniques for obtaining accurate cross sectional data. The results from commonly-used 2D methods can be subject to systematic errors in areal cross section that exceed magnitudes of 10 % on average. In particular, the pole simplified method has showed a clear tendency to understimate areas. Laser profilemeter results show that further research on calibrating optical devices for a variety of soil conditions must be carried out to improve its performance. For volume estimations, photo-reconstruction results provided an excellent approximation to terrestrial laser data and demonstrate that this new remote sensing technique has a promising application field in soil erosion studies. 2D approaches involved important errors even over short measurement distances. However, as well as accuracy, the cost and time requirements of a technique must be considered.

  2. Rainfall erosivity in New Zealand

    Science.gov (United States)

    Klik, Andreas; Haas, Kathrin; Dvorackova, Anna; Fuller, Ian

    2014-05-01

    Rainfall and its kinetic energy expressed by the rainfall erosivity is the main driver of soil erosion processes by water. The Rainfall-Runoff Erosivity Factor (R) of the Revised Universal Soil Loss Equation is one oft he most widely used parameters describing rainfall erosivity. This factor includes the cumulative effects of the many moderate-sized storms as well as the effects oft he occasional severe ones: R quantifies the effect of raindrop impact and reflects the amopunt and rate of runoff associated with the rain. New Zealand is geologically young and not comparable with any other country in the world. Inordinately high rainfall and strong prevailing winds are New Zealand's dominant climatic features. Annual rainfall up to 15000 mm, steep slopes, small catchments and earthquakes are the perfect basis for a high rate of natural and accelerated erosion. Due to the multifacted landscape of New Zealand its location as island between the Pacific and the Tasmanian Sea there is a high gradient in precipitation between North and South Island as well as between West and East Coast. The objective of this study was to determine the R-factor for the different climatic regions in New Zealand, in order to create a rainfall erosivity map. We used rainfall data (breakpoint data in 10-min intervals) from 34 gauging stations for the calcuation of the rainfall erosivity. 15 stations were located on the North Island and 19 stations on the South Island. From these stations, a total of 397 station years with 12710 rainstorms were analyzed. The kinetic energy for each rainfall event was calculated based on the equation by Brown and Foster (1987), using the breakpoint precipitation data for each storm. On average, a mean annual precipitation of 1357 mm was obtained from the 15 observed stations on the North Island. Rainfall distribution throughout the year is relatively even with 22-24% of annual rainfall occurring in spring , fall and winter and 31% in summer. On the South Island

  3. Patterns of magnetic resonance imaging bone erosion in rheumatoid arthritis--which bones are most frequently involved and show the most change?

    DEFF Research Database (Denmark)

    Østergaard, Mikkel; Møller Døhn, Uffe; Duer-Jensen, A

    2011-01-01

    To investigate by magnetic resonance imaging (MRI) which bones in wrists and metacarpophalangeal (MCP) joints most frequently show bone erosions, and which most frequently demonstrate erosive progression, in early and established rheumatoid arthritis (RA).......To investigate by magnetic resonance imaging (MRI) which bones in wrists and metacarpophalangeal (MCP) joints most frequently show bone erosions, and which most frequently demonstrate erosive progression, in early and established rheumatoid arthritis (RA)....

  4. Viewpoint: Sustainability of pinon-juniper ecosystems - A unifying perspective of soil erosion thresholds

    Science.gov (United States)

    Davenport, D.W.; Breshears, D.D.; Wilcox, B.P.; Allen, C.D.

    1998-01-01

    Many pinon-juniper ecosystem in the western U.S. are subject to accelerated erosion while others are undergoing little or no erosion. Controversy has developed over whether invading or encroaching pinon and juniper species are inherently harmful to rangeland ecosystems. We developed a conceptual model of soil erosion in pinon-jumper ecosystems that is consistent with both sides of the controversy and suggests that the diverse perspectives on this issue arise from threshold effects operating under very different site conditions. Soil erosion rate can be viewed as a function of (1) site erosion potential (SEP), determined by climate, geomorphology and soil erodibility; and (2) ground cover. Site erosion potential and cove act synergistically to determine soil erosion rates, as evident even from simple USLE predictions of erosion. In pinon-juniper ecosystem with high SEP, the erosion rate is highly sensitive to ground cover and can cross a threshold so that erosion increases dramatically in response to a small decrease in cover. The sensitivity of erosion rate to SEP and cover can be visualized as a cusp catastrophe surface on which changes may occur rapidly and irreversibly. The mechanisms associated with a rapid shift from low to high erosion rate can be illustrated using percolation theory to incorporate spatial, temporal, and scale-dependent patterns of water storage capacity on a hillslope. Percolation theory demonstrates how hillslope runoff can undergo a threshold response to a minor change in storage capacity. Our conceptual model suggests that pinion and juniper contribute to accelerated erosion only under a limited range of site conditions which, however, may exist over large areas.

  5. Climate-sensitive feedbacks between hillslope processes and fluvial erosion in sediment-driven incision models

    Science.gov (United States)

    Skov, Daniel S.; Egholm, David L.

    2016-04-01

    Surface erosion and sediment production seem to have accelerated globally as climate cooled in the Late Cenozoic, [Molnar, P. 2004, Herman et al 2013]. Glaciers emerged in many high mountain ranges during the Quaternary, and glaciation therefore represents a likely explanation for faster erosion in such places. Still, observations and measurements point to increases in erosion rates also in landscapes where erosion is driven mainly by fluvial processes [Lease and Ehlers (2013), Reusser (2004)]. Flume experiments and fieldwork have shown that rates of incision are to a large degree controlled by the sediment load of streams [e.g. Sklar and Dietrich (2001), Beer and Turowski (2015)]. This realization led to the formulation of sediment-flux dependent incision models [Sklar and Dietrich (2004)]. The sediment-flux dependence links incision in the channels to hillslope processes that supply sediment to the channels. The rates of weathering and soil transport on the hillslopes are processes that are likely to respond to changing temperatures, e.g. because of vegetation changes or the occurrence of frost. In this study, we perform computational landscape evolution experiments, where the coupling between fluvial incision and hillslope processes is accounted for by coupling a sediment-flux-dependent model for fluvial incision to a climate-dependent model for weathering and hillslope sediment transport. The computational experiments first of all demonstrate a strong positive feedback between channel and hillslope processes. In general, faster weathering leads to higher rates of channel incision, which further increases the weathering rates, mainly because of hillslope steepening. Slower weathering leads to the opposite result. The experiments also demonstrate, however, that the feedbacks vary significantly between different parts of a drainage network. For example, increasing hillslope sediment production may accelerate incision in the upper parts of the catchment, while at

  6. 香根草篱防治红壤坡耕地侵蚀效果的研究%Control Effect of Hedge of Vetiver Grass on Red Soil Sloping Land Erosion

    Institute of Scientific and Technical Information of China (English)

    黄欠如; 章新亮; 李清平; 余喜初; 贺湘逸; 周慕卿

    2001-01-01

    The experiment in control effect of the hedge of vetiver grass on red soil sloping land erosion was conducted during 1997~1999, the results showed that the hedge of vetiver grass could decrease runoff, soil loss and total nutrient loss by 60.1%~72.4%, 56.2%~77.9% and 69.2%~90.4% respectively, and could enhance the critical value of rainfall of causing soil loss by 2.7mm and yearly average peanut yield by 10.3%. In 2~3 years after planting vetiver grass, its effect of conserving soil and water would be close to that of terrace land.%1997~1999年试验结果表明:丘陵红壤坡耕地实施香根草篱开发,可使地表径流量、土壤冲刷量和养分流失总量分别减少60.1%~72.4%、56.2%~77.9%、69.2%~90.4%,可使土壤临界侵蚀量提高2.7mm,花生产量年均提高10.3%。而且,2~3年后,香根草篱的水土保持效果接近于梯地。

  7. Theoretical and practical feasibility demonstration of a micrometric remotely controlled pre-alignment system for the CLIC linear collider

    CERN Document Server

    Mainaud Durand, H; Chritin, N; Griffet, S; Kemppinen, J; Sosin, M; Touze, T

    2011-01-01

    The active pre-alignment of the Compact Linear Collider (CLIC) is one of the key points of the project: the components must be pre-aligned w.r.t. a straight line within a few microns over a sliding window of 200 m, along the two linacs of 20 km each. The proposed solution consists of stretched wires of more than 200 m, overlapping over half of their length, which will be the reference of alignment. Wire Positioning Sensors (WPS), coupled to the supports to be pre-aligned, will perform precise and accurate measurements within a few microns w.r.t. these wires. A micrometric fiducialisation of the components and a micrometric alignment of the components on common supports will make the strategy of pre-alignment complete. In this paper, the global strategy of active pre-alignment is detailed and illustrated by the latest results demonstrating the feasibility of the proposed solution.

  8. Global peat erosion risk assessment for the 21st Century

    Science.gov (United States)

    Li, Pengfei; Irvine, Brian; Holden, Joseph

    2015-04-01

    Many peatlands across the world are suffering from degradation and erosion exacerbated by human influences. Blanket peat erosion has adverse impacts on terrestrial and aquatic habitats, reservoir capacity and water quality, and also leads to accelerated carbon release. Bioclimatic modelling suggests that some areas, which are currently suitable for active peat growth, may be no longer under a climate supporting the accumulation of peat by the end of the century. Peat erosion in these marginal regions is thus more likely. A recently developed blanket peat erosion model, PESERA-PEAT, was established through significantly modifying the grid version of the Pan-European Soil Erosion Assessment model (PESERA-GRID) to explicitly include the freeze-thaw and desiccation processes, which appear to be the crucial drivers of peat erosion, and typical land management practices in blanket peatlands such as artificial drainage, grazing and managed burning. Freeze-thaw and desiccation are estimated based on climate (i.e. temperature) and soil moisture conditions. Land management practices interact with hydrology, erosion and vegetation growth via their influence on vegetation cover, biomass and soil moisture condition. The model has been demonstrated to be robust for blanket peat erosion modelling with riverine sediment flux data in the UK. In this paper, the PESERA-PEAT model is applied to investigate the impact of environmental change on the blanket peat erosion at a global scale. Climatic scenarios to the end of 21st Century were derived, as part of the QUEST-GSI initiative, from the outputs of seven global climate models: CGCM3 and CCCMA (Canada); CSIRO Mark III (Australia); IPSL (France); ECHAM5 (Germany); CCSM (US National Centre for Atmospheric Research (NCAR)); HadCM3 and HadGEM1 (UK). Land management practice such as artificial drainage is considered to examine if it is possible to buffer the impact of climate change on erosion through managing blanket peatlands in

  9. Remote Health Consultations Supported by a Diabetes Management Web Application With a New Glucose Meter Demonstrates Improved Glycemic Control.

    Science.gov (United States)

    Grady, Mike; Cameron, Hilary; Levy, Brian L; Katz, Laurence B

    2016-05-01

    Cloud-connected diabetes applications enable health care professionals (HCPs) to monitor patient progress and offer the potential for remote consultations. OneTouch Reveal (OTR) is a cloud-based web application that aggregates data from blood glucose (BG) meters or insulin pumps and provides analytics to help patients and HCPs make more informed treatment and lifestyle decisions. This study assessed the experience of patients using OTR and the OneTouch Verio (OTV) BG meter and determined the extent of changes in glycemic control. Subjects with T1DM (23) or T2DM (17) uploaded BG meter results to OTR for 12 weeks. HCPs remotely reviewed progress using OTR and delivered telephone consultations at 4 and 8 weeks based on OTR insights. After 12 weeks, mean HbA1c decreased by 0.4% (P web application in combination with the OTV meter helped subjects with T1DM and T2DM effectively manage their diabetes and was associated with improved BG control over 12 weeks. Real-time visibility to subject data may help HCPs deliver focused and effective remote consultations. © 2015 Diabetes Technology Society.

  10. Construction and tests of an in-beam PET-like demonstrator for hadrontherapy beam ballistic control

    Science.gov (United States)

    Montarou, G.; Bony, M.; Busato, E.; Chadelas, R.; Donnarieix, D.; Force, P.; Guicheney, C.; Insa, C.; Lambert, D.; Lestand, L.; Magne, M.; Martin, F.; Millardet, C.; Nivoix, M.; Podlyski, F.; Rozes, A.

    2017-02-01

    We present the first results obtained with a detector, called Large Area Pixelized Detector (LAPD), dedicated to the study the ballistic control of the beam delivered to the patient by in-beam and real time detection of secondary particles, emitted during its irradiation in the context of hadrontherapy. These particles are 511 keV γ from the annihilation of a positron issued from the β+ emitters induced in the patient tissues along the beam path. The LAPD basic concepts are similar to a conventional PET camera. The 511 keV γ are detected and the reconstructed lines of response allow to measure the β+ activity distribution. Nevertheless, when trying to use γ from positron annihilation for the ballistic control in hadrontherapy, the large prompt γ background should be taken into account and properly rejected. First reconstruction results, obtained with a phantom filled with a high intensity FDG source at the cancer research centre of Clermont-Ferrand are shown. We also report results of measurements performed at the Heidelberg Ion-Beam Therapy Centre with one third of the detector, using proton and carbon ion beams.

  11. Two-dimensional time dependent hurricane overwash and erosion modeling at Santa Rosa Island

    Science.gov (United States)

    McCall, R.T.; Van Theil de Vries, J. S. M.; Plant, N.G.; Van Dongeren, A. R.; Roelvink, J.A.; Thompson, D.M.; Reniers, A.J.H.M.

    2010-01-01

    A 2DH numerical, model which is capable of computing nearshore circulation and morphodynamics, including dune erosion, breaching and overwash, is used to simulate overwash caused by Hurricane Ivan (2004) on a barrier island. The model is forced using parametric wave and surge time series based on field data and large-scale numerical model results. The model predicted beach face and dune erosion reasonably well as well as the development of washover fans. Furthermore, the model demonstrated considerable quantitative skill (upwards of 66% of variance explained, maximum bias - 0.21 m) in hindcasting the post-storm shape and elevation of the subaerial barrier island when a sheet flow sediment transport limiter was applied. The prediction skill ranged between 0.66 and 0.77 in a series of sensitivity tests in which several hydraulic forcing parameters were varied. The sensitivity studies showed that the variations in the incident wave height and wave period affected the entire simulated island morphology while variations in the surge level gradient between the ocean and back barrier bay affected the amount of deposition on the back barrier and in the back barrier bay. The model sensitivity to the sheet flow sediment transport limiter, which served as a proxy for unknown factors controlling the resistance to erosion, was significantly greater than the sensitivity to the hydraulic forcing parameters. If no limiter was applied the simulated morphological response of the barrier island was an order of magnitude greater than the measured morphological response.

  12. Glacial erosion during orogenesis: A study of the intraplate Eurekan Orogeny of Ellesmere Island.

    Science.gov (United States)

    Housam, J. M.; Pysklywec, R. N.; Heron, P.; Stephenson, R.

    2015-12-01

    The Eurekan Orogeny of northeastern Ellesmere Island in the Canadian arctic was formed as a result of mountain-building processes in the Paleogene. The orogen developed relatively distant from any active convergent plate boundaries making it a representation of a class of intraplate mountain-building. In this work we investigate the geodynamics of the Eurekan and in particular focus on the potential role of glacial erosion in modifying the orogenesis. The study is motivated by important recent research that has demonstrated a significant interaction between (climate-controlled) surface processes and solid Earth tectonics at collision. Glacial erosion is thought to have the capability of eroding at a rate which matches with that of rock uplift in active orogens, referred to as the "buzz saw" effect of glaciers. Using the geodynamic modelling code of SOPALE we developed forward 2D models of the idealized Ellesmerian lithospheric structure and imposed shortening to explore Eurekan-style orogenic deformation. In the numerical experiments, we modified the erosional algorithm in the model such to investigate various implementations of the glacial buzz saw. The model results show how the surface topography and internal lithospheric structure of the orogeny are modified by variable glacial erosion. In addition to illustrating how the Eurekan orogeny may have evolved, the results provide insight into how the generic orogenic zones may develop in a glacial environment.

  13. The impact of stannous, fluoride ions and its combination on enamel pellicle proteome and dental erosion prevention.

    Directory of Open Access Journals (Sweden)

    A A Algarni

    Full Text Available To compare the effects of stannous (Sn and fluoride (F ions and their combination on acquired enamel pellicle (AEP protein composition (proteome experiment, and protection against dental erosion (functional experiment.In the proteome experiment, bovine enamel specimens were incubated in whole saliva supernatant for 24h for AEP formation. They were randomly assigned to 4 groups (n=10, according to the rinse treatment: Sn (800ppm/6.7mM, SnCl2, F (225ppm/13mM, NaF, Sn and F combination (Sn+F and deionized water (DIW, negative control. The specimens were immersed 3× in the test rinses for 2min, 2h apart. Pellicles were collected, digested, and analyzed for protein content using liquid chromatography electrospray ionization tandem mass spectrometry. In the functional experiment, bovine enamel specimens (n=10 were similarly treated for pellicle formation. Then, they were subjected to a five-day erosion cycling model, consisting of 5min erosive challenges (15.6 mM citric acid, pH 2.6, 6×/d and 2min treatment with the rinses containing Sn, F or Sn+F (3×/d. Between the treatments, all specimens were incubated in whole saliva supernatant. Surface loss was determined by profilometry.Our proteome approach on bovine enamel identified 72 proteins that were common to all groups. AEP of enamel treated with Sn+F demonstrated higher abundance for most of the identified proteins than the other groups. The functional experiment showed reduction of enamel surface loss for Sn+F (89%, Sn (67% and F (42% compared to DIW (all significantly different, p<0.05.This study highlighted that anti-erosion rinses (e.g. Sn+F can modify quantitatively and qualitatively the AEP formed on bovine enamel. Moreover, our study demonstrated a combinatory effect that amplified the anti-erosive protection on tooth surface.

  14. Electro-optic control of photographic imaging quality through ‘Smart Glass’ windows in optics demonstrations

    Science.gov (United States)

    Ozolinsh, Maris; Paulins, Paulis

    2017-09-01

    An experimental setup allowing the modeling of conditions in optical devices and in the eye at various degrees of scattering such as cataract pathology in human eyes is presented. The scattering in cells of polymer-dispersed liquid crystals (PDLCs) and ‘Smart Glass’ windows is used in the modeling experiments. Both applications are used as optical obstacles placed in different positions of the optical information flow pathway either directly on the stimuli demonstration computer screen or mounted directly after the image-formation lens of a digital camera. The degree of scattering is changed continuously by applying an AC voltage of up to 30-80 V to the PDLC cell. The setup uses a camera with 14 bit depth and a 24 mm focal length lens. Light-emitting diodes and diode-pumped solid-state lasers emitting radiation of different wavelengths are used as portable small-divergence light sources in the experiments. Image formation, optical system point spread function, modulation transfer functions, and system resolution limits are determined for such sample optical systems in student optics and optometry experimental exercises.

  15. Demonstration of SCR technology for the control of NOx emissions from high-sulfur coal-fired utility boilers

    Energy Technology Data Exchange (ETDEWEB)

    Hinton, W.S. [W.S. Hinton and Associates, Cantonment, FL (United States); Maxwell, J.D.; Healy, E.C.; Hardman, R.R. [Southern Company Services, Inc., Birmingham, AL (United States); Baldwin, A.L. [Dept. of Energy, Pittsburgh, PA (United States)

    1997-12-31

    This paper describes the completed Innovative Clean Coal Technology project which demonstrated SCR technology for reduction of flue gas NO{sub x} emissions from a utility boiler burning US high-sulfur coal. The project was sponsored by the US Department of Energy, managed and co-funded by Southern Company Services, Inc. on behalf of the Southern Company, and also co-funded by the Electric Power Research Institute and Ontario Hydro. The project was located at Gulf Power Company`s Plant Crist Unit 5 (a 75 MW tangentially-fired boiler burning US coals that had a sulfur content ranging from 2.5--2.9%), near Pensacola, Florida. The test program was conducted for approximately two years to evaluate catalyst deactivation and other SCR operational effects. The SCR test facility had nine reactors: three 2.5 MW (5,000 scfm), and operated on low-dust flue gas. The reactors operated in parallel with commercially available SCR catalysts obtained from suppliers throughout the world. Long-term performance testing began in July 1993 and was completed in July 1995. A brief test facility description and the results of the project are presented in this paper.

  16. MR Guidance, Monitoring and Control of Brain HIFU Therapy in Small Animals: In Vivo Demonstration in Rats

    Science.gov (United States)

    Larrat, B.; Pernot, M.; Dervishi, E.; Souilah, A.; Seilhean, D.; Marie, Y.; Boch, A. L.; Aubry, J. F.; Fink, M.; Tanter, M.

    2010-03-01

    In the framework of HIFU transcranial brain therapy, it is mandatory to develop techniques capable of assessing the focusing quality and location before the treatment. Monitoring heat deposition in real time and verifying the extension of the treated area are also important steps. In this study, an imaging protocol is proposed to:1/ locate the US radiation force induced displacement in tissues and quantify the acoustic pressure at focus prior to HIFU; 2/ monitor the temperature rise during HIFU; and 3/ assess the changes in elasticity in the treated area. A 7T MRI scanner was equipped with a home-made stereotactic frame for rats and a US focused transducer working at 1.5 MHz. Such a tool is key for the evaluation of the biological effects of HIFU on brain tissue and tumors. The proposed protocol was successfully tested on 12 rats with and without injected tumors. The accurate localization of the focal point prior to HIFU was demonstrated in vivo. Furthermore, the pressure estimation in situ allowed to accurately simulate the heat deposition at focus and to plan the treatment (electrical power, duration). The temperature measurements were in good accordance with the predicted curves. The elasticity maps showed significant changes after treatment in some cases.

  17. Cytosolic access of Mycobacterium tuberculosis: critical impact of phagosomal acidification control and demonstration of occurrence in vivo.

    Directory of Open Access Journals (Sweden)

    Roxane Simeone

    2015-02-01

    Full Text Available Mycobacterium tuberculosis (Mtb uses efficient strategies to evade the eradication by professional phagocytes, involving--as recently confirmed--escape from phagosomal confinement. While Mtb determinants, such as the ESX-1 type VII secretion system, that contribute to this phenomenon are known, the host cell factors governing this important biological process are yet unexplored. Using a newly developed flow-cytometric approach for Mtb, we show that macrophages expressing the phagosomal bivalent cation transporter Nramp-1, are much less susceptible to phagosomal rupture. Together with results from the use of the phagosome acidification inhibitor bafilomycin, we demonstrate that restriction of phagosomal acidification is a prerequisite for mycobacterial phagosomal rupture and cytosolic contact. Using different in vivo approaches including an enrichment and screen for tracking rare infected phagocytes carrying the CD45.1 hematopoietic allelic marker, we here provide first and unique evidence of M. tuberculosis-mediated phagosomal rupture in mouse spleen and lungs and in numerous phagocyte types. Our results, linking the ability of restriction of phagosome acidification to cytosolic access, provide an important conceptual advance for our knowledge on host processes targeted by Mtb evasion strategies.

  18. Erosion Associated with Seismically-Induced Landslides in the Middle Longmen Shan Region, Eastern Tibetan Plateau, China

    Directory of Open Access Journals (Sweden)

    Zhikun Ren

    2017-08-01

    Full Text Available The 2008 Wenchuan earthquake and associated co-seismic landslide was the most recent expression of the rapid deformation and erosion occurring in the eastern Tibetan Plateau. The erosion associated with co-seismic landslides balances the long-term tectonic uplift in the topographic evolution of the region; however, the quantitative relationship between earthquakes, uplift, and erosion is still unknown. In order to quantitatively distinguish the seismically-induced erosion in the total erosion, here, we quantify the Wenchuan earthquake-induced erosion using the digital elevation model (DEM differential method and previously-reported landslide volumes. Our results show that the seismically-induced erosion is comparable with the pre-earthquake short-term erosion. The seismically-induced erosion rate contributes ~50% of the total erosion rate, which suggests that the local topographic evolution of the middle Longmen Shan region may be closely related to tectonic events, such as the 2008 Wenchuan earthquake. We propose that seismically-induced erosion is a very important component of the total erosion, particularly in active orogenic regions. Our results demonstrate that the remote sensing technique of differential DEM provides a powerful tool for evaluating the volume of co-seismic landslides produced in intermountain regions by strong earthquakes.

  19. Biogeochemistry: The soil carbon erosion paradox

    Science.gov (United States)

    Sanderman, Jonathan; Berhe, Asmeret Asefaw

    2017-04-01

    Erosion is typically thought to degrade soil resources. However, the redistribution of soil carbon across the landscape, caused by erosion, can actually lead to a substantial sink for atmospheric CO2.

  20. Tube erosion in bubbling fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Levy, E.K. [Lehigh Univ., Bethlehem, PA (United States). Energy Research Center; Stallings, J.W. [Electric Power Research Inst., Palo Alto, CA (United States)

    1991-12-31

    This paper reports on experimental and theoretical studies that were preformed of the interaction between bubbles and tubes and tube erosion in fluidized beds. The results are applicable to the erosion of horizontal tubes in the bottom row of a tube bundle in a bubbling bed. Cold model experimental data show that erosion is caused by the impact of bubble wakes on the tubes, with the rate of erosion increasing with the velocity of wake impact with the particle size. Wake impacts resulting from the vertical coalescence of pairs of bubbles directly beneath the tube result in particularly high rates of erosion damage. Theoretical results from a computer simulation of bubbling and erosion show very strong effects of the bed geometry and bubbling conditions on computed rates of erosion. These results show, for example, that the rate of erosion can be very sensitive to the vertical location of the bottom row of tubes with respect to the distributor.

  1. Protective effect of green tea on dentin erosion and abrasion

    Directory of Open Access Journals (Sweden)

    Melissa Thiemi Kato

    2009-12-01

    Full Text Available OBJECTIVE: This in situ study evaluated the protective effect of green tea on dentin erosion (ERO and erosion-abrasion (ABR. MATERIAL AND METHODS: Ten volunteers wore intraoral palatal appliances with bovine dentin specimens subjected to ERO or ERO + toothbrushing abrasion performed immediately (ERO+I-ABR or 30 min after erosion (ERO+30-min-ABR. During 2 experimental 5-day crossover phases, the volunteers rinsed with green tea or water (control, 1 min between each erosive (5 min, cola drink and abrasive challenge (30 s, toothbrushing, 4x/day. Dentin wear was measured by profilometry. RESULTS: The green tea reduced the dentin wear significantly for all conditions compared to control. ERO+I-ABR led to significantly higher wear than ERO, but it was not significantly different from ERO+30-min-ABR. ERO+30-min-ABR provoked significant higher wear than ERO, only for the placebo treatment. CONCLUSIONS: From the results of the present study, it may be concluded that green tea reduces the dentin wear under erosive/abrasive conditions.

  2. Plutonium as a tracer for soil erosion assessment in northeast China

    DEFF Research Database (Denmark)

    Xu, Yihong; Qiao, Jixin; Pan, Shaoming;

    2015-01-01

    Soil erosion is one of the most serious environmental and agricultural problems faced by human society. Assessing intensity is an important issue for controlling soil erosion and improving eco-environmental quality. The suitability of the application of plutonium (Pu) as a tracer for soil erosion...... assessment in northeast China was investigated by comparing with that of 137Cs. Here we build on preliminary work, in which we investigated the potential of Pu as a soil erosion tracer by sampling additional reference sites and potential erosive sites, along the Liaodong Bay region in northeast China, for Pu...... in cultivated land. The baseline inventories of 239+240Pu and 137Cs were 88.4 and 1688Bqm-2 respectively. Soil erosion rates estimated by 239+240Pu tracing method were consistent with those obtained by the 137Cs method, confirming that Pu is an effective tracer with a similar tracing behavior to that of 137Cs...

  3. Scale-free channeling patterns near the onset of erosion of sheared granular beds

    CERN Document Server

    Aussillous, Pascale; Guazzelli, Élisabeth; Yan, Le; Wyart, Matthieu

    2016-01-01

    Erosion shapes our landscape and occurs when a sufficient shear stress is exerted by a fluid on a sedimented layer. What controls erosion at a microscopic level remains debated, especially near the threshold forcing where it stops. Here we study experimentally the collective dynamics of the moving particles, using a set-up where the system spontaneously evolves toward the erosion onset. We find that the spatial organization of the erosion flux is heterogeneous in space, and occurs along channels of local flux $\\sigma$ whose distribution displays scaling near threshold and follows $P(\\sigma)\\sim J/\\sigma$, where $J$ is the mean erosion flux. Channels are strongly correlated in the direction of forcing but not in the transverse direction. We show that these results quantitatively agree with a model where the dynamics is governed by the competition of disorder (which channels mobile particles) and particle interactions (which reduces channeling). These observations support that for laminar flows, erosion is a dy...

  4. Conceptual considerations of evaluate internal erosion phenomenon via no-erosion filter test and continuing erosion filter test

    Directory of Open Access Journals (Sweden)

    Ramos-Rivera Johnatan

    2016-01-01

    Full Text Available Some widely-graded soils may exhibit, under the influence of steady seepage flow, a behaviour in which grains of the finer fraction migrate through the interstices of the matrix formed by the coarser fraction. The migrating fines may accumulate at a downstream location within the soil. Alternatively, and where there is no capacity for retention at the downstream or exit boundary, the behaviour may lead to a washing out and consequent loss of the finer fraction. The phenomenon of erosion is termed internal instability, and the soils are considered internally unstable. Taking into consideration (i the specimen reconstitution by method of compaction, (ii the application of a vertical stress to the specimen, and (iii the use of multi-stage seepage flow with head-control, to measure the origin of a conduit through the coarser fraction, some test devices were conducted by different authors to evaluate this phenomenon, the purpose of this paper is to present some considerations and key aspects about internal erosion in dams and filter compatibility with core material (specimen reconstitution, test procedure, consolidation, seepage flow, test program and its relevance to the reality. The main reason to present this investigation is due to the absence of any specified regulatory or standard test method. Given the importance of filter compatibility of the zoned earth core dam and filter materials, as well the grading stability of each zone in the presence of seepage flow, additional consideration will be given to performing Continuing Erosion Filter (CEF tests on the core-filter interface, using the laboratory permeameter device.

  5. The interaction between soil erosion and soil organisms in temperate agroecosystems: nematode redistribution in tramlines

    Science.gov (United States)

    Baxter, Craig; Rowan, John S.; McKenzie, Blair M.; Neilson, Roy

    2014-05-01

    export with 95% less nematodes exported, compared with the control treatment. We observed wholesale non-selective transport of all nematode trophic groups present in the soil. The findings of this experiment are twofold. Firstly, we demonstrate that soil organisms are transported by erosion processes and confirm that tramlines are key hydrological pathways. Secondly, we highlight practical on-farm solutions that have potential to decrease soil organism losses. These results provide important baseline information to improve our understanding of soil erosion impacts to the wider soil ecosystem. The results help to inform soil and water conservation measures for sustainable agriculture.

  6. GASIS demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Vidas, E.H. [Energy and Environmental Analysis, Inc., Arlington, VA (United States)

    1995-04-01

    A prototype of the GASIS database and retrieval software has been developed and is the subject of this poster session and computer demonstration. The prototype consists of test or preliminary versions of the GASIS Reservoir Data System and Source Directory datasets and the software for query and retrieval. The prototype reservoir database covers the Rocky Mountain region and contains the full GASIS data matrix (all GASIS data elements) that will eventually be included on the CD-ROM. It is populated for development purposes primarily by the information included in the Rocky Mountain Gas Atlas. The software has been developed specifically for GASIS using Foxpro for Windows. The application is an executable file that does not require Foxpro to run. The reservoir database software includes query and retrieval, screen display, report generation, and data export functions. Basic queries by state, basin, or field name will be assisted by scrolling selection lists. A detailed query screen will allow record selection on the basis of any data field, such as depth, cumulative production, or geological age. Logical operators can be applied to any-numeric data element or combination of elements. Screen display includes a {open_quotes}browse{close_quotes} display with one record per row and a detailed single record display. Datasets can be exported in standard formats for manipulation with other software packages. The Source Directory software will allow record retrieval by database type or subject area.

  7. Development and Demonstration of a Self-Calibrating Pseudolite Array for Task Level Control of a Planetary Rover

    Science.gov (United States)

    Rock, Stephen M.; LeMaster, Edward A.

    2001-01-01

    Pseudolites can extend the availability of GPS-type positioning systems to a wide range of applications not possible with satellite-only GPS. One such application is Mars exploration, where the centimeter-level accuracy and high repeatability of CDGPS would make it attractive for rover positioning during autonomous exploration, sample collection, and habitat construction if it were available. Pseudolites distributed on the surface would allow multiple rovers and/or astronauts to share a common navigational reference. This would help enable cooperation for complicated science tasks, reducing the need for instructions from Earth and increasing the likelihood of mission success. Conventional GPS Pseudolite arrays require that the devices be pre-calibrated through a Survey of their locations, typically to sub-centimeter accuracy. This is a problematic task for robots on the surface of another planet. By using the GPS signals that the Pseudolites broadcast, however, it is possible to have the array self-survey its own relative locations, creating a SelfCalibrating Pseudolite Array (SCPA). This requires the use of GPS transceivers instead of standard pseudolites. Surveying can be done either at carrier- or code-phase levels. An overview of SCPA capabilities, system requirements, and self-calibration algorithms is presented in another work. The Aerospace Robotics Laboratory at Statif0id has developed a fully operational prototype SCPA. The array is able to determine the range between any two transceivers with either code- or carrier-phase accuracy, and uses this inter-transceiver ranging to determine the at-ray geometry. This paper presents results from field tests conducted at Stanford University demonstrating the accuracy of inter-transceiver ranging and its viability and utility for array localization, and shows how transceiver motion may be utilized to refine the array estimate by accurately determining carrier-phase integers and line biases. It also summarizes the

  8. Plume Mitigation: Soil Erosion and Lunar Prospecting Sensor Project

    Science.gov (United States)

    Metzger, Philip T.

    2014-01-01

    Demonstrate feasibility of the simplest, lowest-mass method of measuring density of a cloud of lunar soil ejected by rocket exhaust, using new math techniques with a small baseline laser/camera system. Focus is on exploring the erosion process that occurs when the exhaust plume of a lunar rocket impacts the regolith. Also, predicting the behavior of the lunar soil that would be blasted from a lunar landing/launch site shall assist in better design and protection of any future lunar settlement from scouring of structures and equipment. NASA is gathering experimental data to improve soil erosion models and understand how lunar particles enter the plume flow.

  9. Subduction Tectonic Erosion, Sediment Accretion and Arc Collisions in maintaining the Continental Crust

    Science.gov (United States)

    Clift, P.; Vannucchi, P.; Schouten, H.

    2007-12-01

    Estimates of modern continental crustal recycling in subduction zones can be made from plate convergence velocities, the thicknesses of trench sediments, volumes and ages of accretionary complexes together with rates of trench retreat. Plate convergence rates appear to be the primary control on crustal subduction, with convergence >7.5 cm/yr associated with tectonic erosion. Collision of aseismic ridges with trenches drives around two thirds of forearc tectonic erosion over periods >10 m.y.. Globally material subduction at least as deep as the magmatic roots of arc systems is around 3.0 Armstrong Units (1 AU = 1 km3/yr), of which 1.65 AU comprises subducted sediments, with 1.33 AU of eroded forearc crust. Recycling rates along a single margin may show strong temporal variation over 1 m.y. periods. Isotopic variations in Costa Rican tephra suggest that sediment accretion is the most common mode of tectonism, but this is separated by short periods of dramatic erosion that cause net crustal loss. Even where erosion is continuous this can operate in a fast steady-state mode or a slower temporary style. On the Central Andean margin tectonic erosion since 20 Ma has caused trench retreat, but slow subsidence under the coastal zone implies steepening of the forearc taper rather than large scale retreat. The Neogene mass loss rate of 13 km3/m.y./km is 5-10 times lower than the long-term average. Since 2 Ma this rate has slowed further due to underplating under the coastal zone. A climatic role in driving continental erosion and moving the margin into a more accretionary state has been suggested but is hard to demonstrate. Average global mass loss requires that Cenozoic arc productivity lies close to 75 km3/m.y./km if the volume of the continental crust is to be maintained. Efficient accretion of oceanic arc crust is essential in maintaining the total crustal volume. In the classic Taiwan-Luzon example local crustal mass balancing implies that ~90% of the igneous arc crust

  10. On-sky demonstration of low-order wavefront sensing and control with focal plane phase mask coronagraphs

    CERN Document Server

    Singh, Garima; Guyon, Olivier; Baudoz, Pierre; Jovanovic, Nemanja; Martinache, Frantz; Kudo, Tomoyuki; Serabyn, Eugene; Kuhn, Jonas

    2015-01-01

    The ability to characterize exoplanets by spectroscopy of their atmospheres requires direct imaging techniques to isolate planet signal from the bright stellar glare. One of the limitations with the direct detection of exoplanets, either with ground- or space-based coronagraphs, is pointing errors and other low-order wavefront aberrations. The coronagraphic detection sensitivity at the diffraction limit therefore depends on how well low-order aberrations upstream of the focal plane mask are corrected. To prevent starlight leakage at the inner working angle of a phase mask coronagraph, we have introduced a Lyot-based low-order wavefront sensor (LLOWFS), which senses aberrations using the rejected starlight diffracted at the Lyot plane. In this paper, we present the implementation, testing and results of LLOWFS on the Subaru Coronagraphic Extreme Adaptive Optics system (SCExAO) at the Subaru Telescope. We have controlled thirty-five Zernike modes of a H-band vector vortex coronagraph in the laboratory and ten Z...

  11. Surface rippling by oblique ion incidence during plasma etching of silicon: Experimental demonstration using sheath control plates

    Science.gov (United States)

    Nakazaki, Nobuya; Matsumoto, Haruka; Eriguchi, Koji; Ono, Kouichi

    2015-09-01

    In the microfabrication of 3D transistors (e.g. Fin-FET), the sidewall roughness, such as LER and LWR caused by off-normal or oblique ion incidence during plasma etching, is a critical issue to be resolved, which in turn requires a better understanding of the effects of ion incidence angle θi on surface roughening. This paper presents surface roughening and rippling by oblique ion incidence during inductively coupled plasma etching of Si in Cl2, using the experimental setup as in our previous study. The oblique ion incidence was achieved by sheath control plates, which were placed on and electrically connected to the wafer stage. The plates had slits to vary the sheath structure thereon and to extract ions from plasma to samples on the bottom and/or side of the slits. The results indicated that at θi ~ 40° or oblique incidence; ripple structures were formed on surfaces perpendicularly to the direction of ion incidence, on the other hand, at θi ~ 80° or grazing incidence, small ripples or slit like grooves were formed on surfaces parallel to the direction of ion incidence, as predicted in our previous numerical investigations.

  12. Experimental demonstration of two methods for controlling the group delay in a system with photonic-crystal resonators coupled to a waveguide.

    Science.gov (United States)

    Huo, Yijie; Sandhu, Sunil; Pan, Jun; Stuhrmann, Norbert; Povinelli, Michelle L; Kahn, Joseph M; Harris, James S; Fejer, Martin M; Fan, Shanhui

    2011-04-15

    We measure the group delay in an on-chip photonic-crystal device with two resonators side coupled to a waveguide. We demonstrate that such a group delay can be controlled by tuning either the propagation phase of the waveguide or the frequency of the resonators.

  13. Soil Erosion. LC Science Tracer Bullet.

    Science.gov (United States)

    Buydos, John F., Comp.

    Soil erosion is the detachment and movement of topsoil or soil material from the upper part of the soil profile. It may occur in the form of rill, gully, sheet, or wind erosion. Agents of erosion may be water, wind, glacial ice, agricultural implements, machinery, and animals. Soil conservation measures require a thorough understanding of the…

  14. Soil Erosion Risk Assessment and Modelling

    Science.gov (United States)

    Fister, Wolfgang; Kuhn, Nikolaus J.; Heckrath, Goswin

    2013-04-01

    Soil erosion is a phenomenon with relevance for many research topics in the geosciences. Consequently, PhD students with many different backgrounds are exposed to soil erosion related questions during their research. These students require a compact, but detailed introduction to erosion processes, the risks associated with erosion, but also tools to assess and study erosion related questions ranging from a simple risk assessment to effects of climate change on erosion-related effects on geochemistry on various scales. The PhD course on Soil Erosion Risk Assessment and Modelling offered by the University of Aarhus and conducted jointly with the University of Basel is aimed at graduate students with degrees in the geosciences and a PhD research topic with a link to soil erosion. The course offers a unique introduction to erosion processes, conventional risk assessment and field-truthing of results. This is achieved by combing lectures, mapping, erosion experiments, and GIS-based erosion modelling. A particular mark of the course design is the direct link between the results of each part of the course activities. This ensures the achievement of a holistic understanding of erosion in the environment as a key learning outcome.

  15. Cropping system effects on wind erosion potential

    Science.gov (United States)

    Wind erosion of soil is a destructive process impacting crop productivity and human health and safety. The mechanics of wind erosion and soil properties that influence erosion are well understood. Less well-studied are the effects that cropping intensity has upon those soil properties. We collected ...

  16. Mapping monthly rainfall erosivity in Europe

    DEFF Research Database (Denmark)

    Ballabio, C; Meusburger, K; Klik, A

    2017-01-01

    Rainfall erosivity as a dynamic factor of soil loss by water erosion is modelled intra-annually for the first time at European scale. The development of Rainfall Erosivity Database at European Scale (REDES) and its 2015 update with the extension to monthly component allowed to develop monthly and...

  17. Inhibition of erosive wear by fluoride varnish

    NARCIS (Netherlands)

    Vieira, A.; Jager, D. H. J.; Ruben, J. L.; Huysmans, M. C. D. N. J. M.

    2007-01-01

    It has been suggested that fluoride products with a protective mechanical component are advantageous in the prevention of erosive wear. The aim of this study was to evaluate in situ the effect of fluoride varnish (FV) in the prevention of wear due to erosion and combined erosion and toothbrush abras

  18. Natural and anthropogenic rates of soil erosion

    Science.gov (United States)

    Regions of land that are brought into crop production from native vegetation typically undergo a period of soil erosion instability, and long term erosion rates are greater than for natural lands as long as the land continues being used for crop production. Average rates of soil erosion under natur...

  19. Soil erosion in humid regions: a review

    Science.gov (United States)

    Daniel J. Holz; Karl W.J. Williard; Pamela J. Edwards; Jon E. Schoonover

    2015-01-01

    Soil erosion has significant implications for land productivity and surface water quality, as sediment is the leading water pollutant worldwide. Here, erosion processes are defined. The dominant factors influencing soil erosion in humid areas are reviewed, with an emphasis on the roles of precipitation, soil moisture, soil porosity, slope steepness and length,...

  20. Inhibition of erosive wear by fluoride varnish

    NARCIS (Netherlands)

    Vieira, A.; Jager, D. H. J.; Ruben, J. L.; Huysmans, M. C. D. N. J. M.

    2007-01-01

    It has been suggested that fluoride products with a protective mechanical component are advantageous in the prevention of erosive wear. The aim of this study was to evaluate in situ the effect of fluoride varnish (FV) in the prevention of wear due to erosion and combined erosion and toothbrush