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Sample records for surge flow furrow

  1. Field assessment of surge and continuous furrow irrigation methods in relation to tillage systems

    Science.gov (United States)

    Mattar, Mohamed A.; El-Saadawy, Mohamed A.; Helmy, Mamdouh A.; Sorour, Hussien M.

    2017-04-01

    Surge flow irrigation is one of the irrigation techniques for controlling furrow irrigation. The aim of this study was to investigate the effect of surge furrow irrigation on water management compared with continuous irrigation for different tillage systems. An experimental field was treated with various tillage systems (mouldboard plough, chisel plough and rotary plough) and water irrigation application methods (continuous flow, control) in which irrigation water was applied continuously, and surge flow (3-surges, 4-surges and 5-surges) in which irrigation water was applied intermittently until it reached the tail end of the furrow. The results showed that water savings obtained using the surge technique were 18.58, 11.84 and 18.93% lower water use than with continuous flow, for the mouldboard, chisel and rotary ploughs, respectively. The 3-surges treatment with the rotary plough reduced the advance time by 25.36% from that for continuous irrigation. The 4-surges treatment with the mouldboard plough had the highest water application efficiency (88.13%). The 3-surges treatment with the rotary plough had the highest distribution uniformity (85.01%). The rotary plough did not cause as much soil aeration around the root system as the other tillage systems. The field research provided information about surge flow, aimed at reducing advance times and increasing irrigation efficiency.

  2. Dependence between sea surge, river flow and precipitation in south and west Britain

    Directory of Open Access Journals (Sweden)

    C. Svensson

    2004-01-01

    Full Text Available Estuaries around Great Britain may be at heightened risk of flooding because of the simultaneous occurrence of extreme sea surge and river flow, both of which may be caused by mid-latitude cyclones. A measure especially suited for extremes was employed to estimate dependence between river flow and sea surge. To assist in the interpretation of why flow-surge dependence occurs in some areas and not in others, the dependence between precipitation and surge and between precipitation and river flow was also studied. Case studies of the meteorological situations leading to high surges and/or river flows were also carried out. The present study concerns catchments draining to the south and west coasts of Great Britain. Statistically significant dependence between river flow and daily maximum sea surge may be found at catchments spread along most of this coastline. However, higher dependence is generally found in catchments in hilly areas with a southerly to westerly aspect. Here, precipitation in south-westerly airflow, which is generally the quadrant of prevailing winds, will be enhanced orographically as the first higher ground is encountered. The sloping catchments may respond quickly to the abundant rainfall and the flow peak may arrive in the estuary on the same day as a large sea surge is produced by the winds and low atmospheric pressure associated with the cyclone. There are three regions where flow-surge dependence is strong: the western part of the English south coast, southern Wales and around the Solway Firth. To reduce the influence of tide-surge interaction on the dependence analysis, the dependence between river flow and daily maximum surge occurring at high tide was estimated. The general pattern of areas with higher dependence is similar to that using the daily maximum surge. The dependence between river flow and daily maximum sea surge is often strongest when surge and flow occur on the same day. The west coast from Wales and

  3. Modeling the thermally governed transient flow surges in multitube condensing flow systems with thermal and flow distribution asymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Wedekind, G.L.; Bhatt, B.L. (Oakland Univ., Rochester, MI (United States))

    1989-08-01

    In a tube-type condenser involving complete condensation, small changes in the inlet vapor flow rate momentarily cause very large transient surges in the outlet liquid flow rate. An equivalent single-tube model is proposed that predicts these transient flow surges for a multitube system. The model, based upon a system mean void fraction model developed earlier, includes the effects of thermal and flow distribution asymmetry associated with each individual condenser tube in the multitube system. Theoretical and experimental verification for a two-tube system is presented.

  4. Runoff-generated debris flows: observations and modeling of surge initiation, magnitude, and frequency

    Science.gov (United States)

    Kean, Jason W.; McCoy, Scott W.; Tucker, Gregory E.; Staley, Dennis M.; Coe, Jeffrey A.

    2013-01-01

    Runoff during intense rainstorms plays a major role in generating debris flows in many alpine areas and burned steeplands. Yet compared to debris flow initiation from shallow landslides, the mechanics by which runoff generates a debris flow are less understood. To better understand debris flow initiation by surface water runoff, we monitored flow stage and rainfall associated with debris flows in the headwaters of two small catchments: a bedrock-dominated alpine basin in central Colorado (0.06 km2) and a recently burned area in southern California (0.01 km2). We also obtained video footage of debris flow initiation and flow dynamics from three cameras at the Colorado site. Stage observations at both sites display distinct patterns in debris flow surge characteristics relative to rainfall intensity (I). We observe small, quasiperiodic surges at low I; large, quasiperiodic surges at intermediate I; and a single large surge followed by small-amplitude fluctuations about a more steady high flow at high I. Video observations of surge formation lead us to the hypothesis that these flow patterns are controlled by upstream variations in channel slope, in which low-gradient sections act as “sediment capacitors,” temporarily storing incoming bed load transported by water flow and periodically releasing the accumulated sediment as a debris flow surge. To explore this hypothesis, we develop a simple one-dimensional morphodynamic model of a sediment capacitor that consists of a system of coupled equations for water flow, bed load transport, slope stability, and mass flow. This model reproduces the essential patterns in surge magnitude and frequency with rainfall intensity observed at the two field sites and provides a new framework for predicting the runoff threshold for debris flow initiation in a burned or alpine setting.

  5. 3D Simulations of a Pyroclastic Surge as an Example of a Compressible Suspension Flow

    National Research Council Canada - National Science Library

    ISHIMINE, Yasuhiro

    2004-01-01

    .... As a conspicuous example of such a flow, we present three-dimensional numerical simulations of a pyroclastic surge, which spreads laterally over the ground surface during some volcanic eruptions...

  6. Countercurrent Air-Water Flow in a Scale-Down Model of a Pressurizer Surge Line

    Directory of Open Access Journals (Sweden)

    Takashi Futatsugi

    2012-01-01

    Full Text Available Steam generated in a reactor core and water condensed in a pressurizer form a countercurrent flow in a surge line between a hot leg and the pressurizer during reflux cooling. Characteristics of countercurrent flow limitation (CCFL in a 1/10-scale model of the surge line were measured using air and water at atmospheric pressure and room temperature. The experimental results show that CCFL takes place at three different locations, that is, at the upper junction, in the surge line, and at the lower junction, and its characteristics are governed by the most dominating flow limitation among the three. Effects of inclination angle and elbows of the surge line on CCFL characteristics were also investigated experimentally. The effects of inclination angle on CCFL depend on the flow direction, that is, the effect is large for the nearly horizontal flow and small for the vertical flow at the upper junction. The presence of elbows increases the flow limitation in the surge line, whereas the flow limitations at the upper and lower junctions do not depend on the presence of elbows.

  7. Ridge and Furrow Fields

    DEFF Research Database (Denmark)

    Møller, Per Grau

    2016-01-01

    Ridge and furrow is a specific way of ploughing which makes fields of systematic ridges and furrows like a rubbing washboard. They are part of an overall openfield system, but the focus in this paper is on the functionality of the fields. There are many indications that agro-technological reasons...

  8. Numerical study of flow fluctuation attenuation performance of a surge tank

    Institute of Scientific and Technical Information of China (English)

    郭兰兰; 刘正刚; 耿介; 李东; 杜广生

    2013-01-01

    The surge tank plays an important role in ensuring the stability of a water flow standard device. To study the influence of the structure and the working conditions on the regulator performance of a surge tank, a three-dimensional model, including a surge tank, the pipeline and the water tank is built, and the VOF model in the Fluent software is used to simulate the two-phase pulsatile flow in the surge tank. The inlet flow pulsation is defined by the User Defined Functions (UDF), and the outlet flow is set to be a free jet. By calculating the flow fluctuation coefficient of the variation under different flow conditions, the influences of the pulse frequency, the initial water level height and the baffle plate structure on the flow stability are analyzed. It is shown that the surge tank has a good attenuation effect on high-frequency pulsations, there is an optimal initial water level to suppress the fluctuations, the round holes of the baffle should ensure a certain circulation area with the bore diameter small enough to have the necessary damping effect.

  9. Numerical simulation of cavitation surge and vortical flows in a diffuser with swirling flow

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Bin; Wang, Jiong; Xiao, L. Z.; Long, X. [Wuhan University, Hubei (China); Luo, X. [Tsinghua University, Beijing (China); Miyagawa, K. [Waseda University, Tokyo (Japan); Tsujimoto, Yoshinobu [Osaka University, Osaka (Japan)

    2016-06-15

    The strong swirling flow at the exit of the runner of a Francis turbine at part load causes flow instabilities and cavitation surges in the draft tube, deteriorating the performance of the hydraulic power system. The unsteady cavitating turbulent flow in the draft tube is simplified and modeled by a diffuser with swirling flow using the Scale-adaptive simulation method. Unsteady characteristics of the vortex rope structure and the underlying mechanisms for the interactions between the cavitation and the vortices are both revealed. The generation and evolution of the vortex rope structures are demonstrated with the help of the iso-surfaces of the vapor volume fraction and the Qcriterion. Analysis based on the vorticity transport equation suggests that the vortex dilatation term is much larger along the cavity interface in the diffuser inlet and modifies the vorticity field in regions with high density and pressure gradients. The present work is validated by comparing two types of cavitation surges observed experimentally in the literature with further interpretations based on simulations.

  10. Modeling Flood Inundation Induced by River Flow and Storm Surges over a River Basin

    Directory of Open Access Journals (Sweden)

    Wei-Bo Chen

    2014-10-01

    Full Text Available Low-lying coastal regions and their populations are at risk during storm surge events and high freshwater discharges from upriver. An integrated storm surge and flood inundation modeling system was used to simulate storm surge and inundation in the Tsengwen River basin and the adjacent coastal area in southern Taiwan. A three-dimensional hydrodynamic model with an unstructured grid was used, which was driven by the tidal elevation at the open boundaries and freshwater discharge at the upriver boundary. The model was validated against the observed water levels for three typhoon events. The simulation results for the model were in reasonable agreement with the observational data. The model was then applied to investigate the effects of a storm surge, freshwater discharge, and a storm surge combined with freshwater discharge during an extreme typhoon event. The super Typhoon Haiyan (2013 was artificially shifted to hit Taiwan: the modeling results showed that the inundation area and depth would cause severe overbank flow and coastal flooding for a 200 year return period flow. A high-resolution grid model is essential for the accurate simulation of storm surges and inundation.

  11. Mobility of pyroclastic flows and surges at the Soufriere Hills Volcano, Montserrat

    Science.gov (United States)

    Calder, E.S.; Cole, P.D.; Dade, W.B.; Druitt, T.H.; Hoblitt, R.P.; Huppert, H.E.; Ritchie, L.; Sparks, R.S.J.; Young, S.R.

    1999-01-01

    The Soufriere Hills Volcano on Montserrat has produced avalanche-like pyroclastic flows formed by collapse of the unstable lava dome or explosive activity. Pyroclastic flows associated with dome collapse generate overlying dilute surges which detach from and travel beyond their parent flows. The largest surges partially transform by rapid sedimentation into dense secondary pyroclastic flows that pose significant hazards to distal areas. Different kinds of pyroclastic density currents display contrasting mobilities indicated by ratios of total height of fall H, run-out distance L, area inundated A and volume transported V. Dome-collapse flow mobilities (characterised by either L/H or A/V 2/3) resemble those of terrestrial and extraterrestrial cold-rockfalls (Dade and Huppert, 1998). In contrast, fountain-fed pumice flows and fine-grained, secondary pyroclastic flows travel slower but, for comparable initial volumes and heights, can inundate greater areas.

  12. An experimental description of the flow in a centrifugal compressor from alternate stall to surge

    Science.gov (United States)

    Moënne-Loccoz, V.; Trébinjac, I.; Benichou, E.; Goguey, S.; Paoletti, B.; Laucher, P.

    2017-08-01

    The present paper gives the experimental results obtained in a centrifugal compressor stage designed and built by SAFRAN Helicopter Engines. The compressor is composed of inlet guide vanes, a backswept splittered unshrouded impeller, a splittered vaned radial diffuser and axial outlet guide vanes. Previous numerical simulations revealed a particular S-shape pressure rise characteristic at partial rotation speed and predicted an alternate flow pattern in the vaned radial diffuser at low mass flow rate. This alternate flow pattern involves two adjacent vane passages. One passage exhibits very low momentum and a low pressure recovery, whereas the adjacent passage has very high momentum in the passage inlet and diffuses efficiently. Experimental measurements confirm the S-shape of the pressure rise characteristic even if the stability limit experimentally occurs at higher mass flow than numerically predicted. At low mass flow the alternate stall pattern is confirmed thanks to the data obtained by high-frequency pressure sensors. As the compressor is throttled the path to instability has been registered and a first scenario of the surge inception is given. The compressor first experiences a steady alternate stall in the diffuser. As the mass flow decreases, the alternate stall amplifies and triggers the mild surge in the vaned diffuser. An unsteady behavior results from the interaction of the alternate stall and the mild surge. Finally, when the pressure gradient becomes too strong, the alternate stall blows away and the compressor enters into deep surge.

  13. International fund flows: surges, sudden stops, and cyclicality

    NARCIS (Netherlands)

    Li, Suxiao

    2017-01-01

    International fund flows are cross-border investments in domestic equity and bond markets by global investment funds. They have increased dramatically since the 1990s and played an increasingly important role in the transmission of shocks. In this thesis, we examine the drivers of large changes in

  14. International fund flows: surges, sudden stops, and cyclicality

    NARCIS (Netherlands)

    Li, Suxiao

    2017-01-01

    International fund flows are cross-border investments in domestic equity and bond markets by global investment funds. They have increased dramatically since the 1990s and played an increasingly important role in the transmission of shocks. In this thesis, we examine the drivers of large changes in f

  15. International fund flows: surges, sudden stops, and cyclicality

    NARCIS (Netherlands)

    Li, Suxiao

    2017-01-01

    International fund flows are cross-border investments in domestic equity and bond markets by global investment funds. They have increased dramatically since the 1990s and played an increasingly important role in the transmission of shocks. In this thesis, we examine the drivers of large changes in f

  16. Revealing glacier flow and surge dynamics from animated satellite image sequences: examples from the Karakoram

    Science.gov (United States)

    Paul, F.

    2015-11-01

    Although animated images are very popular on the internet, they have so far found only limited use for glaciological applications. With long time series of satellite images becoming increasingly available and glaciers being well recognized for their rapid changes and variable flow dynamics, animated sequences of multiple satellite images reveal glacier dynamics in a time-lapse mode, making the otherwise slow changes of glacier movement visible and understandable to the wider public. For this study, animated image sequences were created for four regions in the central Karakoram mountain range over a 25-year time period (1990-2015) from freely available image quick-looks of orthorectified Landsat scenes. The animations play automatically in a web browser and reveal highly complex patterns of glacier flow and surge dynamics that are difficult to obtain by other methods. In contrast to other regions, surging glaciers in the Karakoram are often small (10 km2 or less), steep, debris-free, and advance for several years to decades at relatively low annual rates (about 100 m a-1). These characteristics overlap with those of non-surge-type glaciers, making a clear identification difficult. However, as in other regions, the surging glaciers in the central Karakoram also show sudden increases of flow velocity and mass waves travelling down glacier. The surges of individual glaciers are generally out of phase, indicating a limited climatic control on their dynamics. On the other hand, nearly all other glaciers in the region are either stable or slightly advancing, indicating balanced or even positive mass budgets over the past few decades.

  17. Comprehensive Mapping of Ice Flow From Landsat 8: Two Years of Surging and Seasonal Change for Alaska's Glaciers, and Counting…

    Science.gov (United States)

    Fahnestock, M. A.; Larsen, C.; Truffer, M.; Scambos, T. A.; Gardner, A. S.

    2015-12-01

    While it has been known for years that rapid changes in ice flow occur on many Alaskan glaciers due to phenomena that span a gamut from tidewater glacier retreat to surging, it has not previously been possible to capture the spatial and temporal extent of this variability. We report on a comprehensive mapping effort, utilizing feature tracking in Landsat 8 imagery, that is producing a spatial and temporal picture of ice flow variations across southern and southeastern Alaska for glaciers half a kilometer in width and larger. We show that coverage and image characteristics for Landsat 8 enable sampling that is sufficient to track seasonal variations in flow speed for tidewater outlets; surge termination, initiation, and surge front propagation; and summer/winter flow variations for other land-terminating systems. Using the example of the 2014-15 surge of Walsh Glacier, seasonal changes on Columbia glacier, and comprehensive mosaics of ice flow across southern Alaska on a quarterly basis, we will demonstrate that we have entered an era when flow variations can be tracked in near real time, over large areas, with coverage suitable to follow evolving seasonal patterns even in frequently cloudy areas. As the Landsat 8 record continues to grow, it becomes possible to delimit surging and non-surging systems based on their flow speed history, rather than incomplete records of past flow and appearance.

  18. Active Flow Control in a Radial Vaned Diffuser for Surge Margin Improvement: A Multislot Suction Strategy

    Directory of Open Access Journals (Sweden)

    Aurélien Marsan

    2017-01-01

    Full Text Available This work is the final step of a research project that aims at evaluating the possibility of delaying the surge of a centrifugal compressor stage using a boundary-layer suction technique. It is based on Reynolds-Averaged Navier-Stokes numerical simulations. Boundary-layer suction is applied within the radial vaned diffuser. Previous work has shown the necessity to take into account the unsteady behavior of the flow when designing the active flow control technique. In this paper, a multislot strategy is designed according to the characteristics of the unsteady pressure field. Its implementation results in a significant increase of the stable operating range predicted by the unsteady RANS numerical model. A hub-corner separation still exists further downstream in the diffuser passage but does not compromise the stability of the compressor stage.

  19. Effect of Coupling Wave and Flow Dynamics on Hurricane Surge and Inundation

    Science.gov (United States)

    2012-01-01

    impacted hurricanes - both by the wind fields as well as by the accompanying surge. Forecasting the extent of the inundation is critical for local...estimate local surge hazards; and in the other, ensemble model runs are used to determine surge values from a set of parameterized storms [Irish et...with the storm surge to create the storm tide. The extent of coastal inundation - flooding of inland surface that is not normally submerged, is

  20. Surge-damping vacuum valve

    Science.gov (United States)

    Bullock, Jack C.; Kelly, Benjamin E.

    1980-01-01

    A valve having a mechanism for damping out flow surges in a vacuum system which utilizes a slotted spring-loaded disk positioned adjacent the valve's vacuum port. Under flow surge conditions, the differential pressure forces the disk into sealing engagement with the vacuum port, thereby restricting the flow path to the slots in the disk damping out the flow surge.

  1. Objective rapid delineation of areas at risk from block-and-ash pyroclastic flows and surges

    Science.gov (United States)

    Widiwijayanti, C.; Voight, B.; Hidayat, D.; Schilling, S. P.

    2009-08-01

    Assessments of pyroclastic flow (PF) hazards are commonly based on mapping of PF and surge deposits and estimations of inundation limits, and/or computer models of varying degrees of sophistication. In volcanic crises a PF hazard map may be sorely needed, but limited time, exposures, or safety aspects may preclude fieldwork, and insufficient time or baseline data may be available for reliable dynamic simulations. We have developed a statistically constrained simulation model for block-and-ash type PFs to estimate potential areas of inundation by adapting methodology from Iverson et al. (Geol Soc America Bull 110:972-984, 1998) for lahars. The predictive equations for block-and-ash PFs are calibrated with data from several volcanoes and given by A = (0.05 to 0.1) V 2/3, B = (35 to 40) V 2/3, where A is cross-sectional area of inundation, B is planimetric area and V is deposit volume. The proportionality coefficients were obtained from regression analyses and comparison of simulations to mapped deposits. The method embeds the predictive equations in a GIS program coupled with DEM topography, using the LAHARZ program of Schilling (1998). Although the method is objective and reproducible, any PF hazard zone so computed should be considered as an approximate guide only, due to uncertainties on the coefficients applicable to individual PFs, the authenticity of DEM details, and the volume of future collapses. The statistical uncertainty of the predictive equations, which imply a factor of two or more in predicting A or B for a specified V, is superposed on the uncertainty of forecasting V for the next PF to descend a particular valley. Multiple inundation zones, produced by simulations using a selected range of volumes, partly accommodate these uncertainties. The resulting maps show graphically that PF inundation potentials are highest nearest volcano sources and along valley thalwegs, and diminish with distance from source and lateral distance from thalweg. The model

  2. Objective rapid delineation of areas at risk from block-and-ash pyroclastic flows and surges

    Science.gov (United States)

    Widiwijayanti, C.; Voight, B.; Hidayat, D.; Schilling, S.P.

    2009-01-01

    Assessments of pyroclastic flow (PF) hazards are commonly based on mapping of PF and surge deposits and estimations of inundation limits, and/or computer models of varying degrees of sophistication. In volcanic crises a PF hazard map may be sorely needed, but limited time, exposures, or safety aspects may preclude fieldwork, and insufficient time or baseline data may be available for reliable dynamic simulations. We have developed a statistically constrained simulation model for block-and-ash type PFs to estimate potential areas of inundation by adapting methodology from Iverson et al. (Geol Soc America Bull 110:972-984, (1998) for lahars. The predictive equations for block-and-ash PFs are calibrated with data from several volcanoes and given by A = (0.05 to 0.1) V2/3, B = (35 to 40) V2/3, where A is cross-sectional area of inundation, B is planimetric area and V is deposit volume. The proportionality coefficients were obtained from regression analyses and comparison of simulations to mapped deposits. The method embeds the predictive equations in a GIS program coupled with DEM topography, using the LAHARZ program of Schilling (1998). Although the method is objective and reproducible, any PF hazard zone so computed should be considered as an approximate guide only, due to uncertainties on the coefficients applicable to individual PFs, the authenticity of DEM details, and the volume of future collapses. The statistical uncertainty of the predictive equations, which imply a factor of two or more in predicting A or B for a specified V, is superposed on the uncertainty of forecasting V for the next PF to descend a particular valley. Multiple inundation zones, produced by simulations using a selected range of volumes, partly accommodate these uncertainties. The resulting maps show graphically that PF inundation potentials are highest nearest volcano sources and along valley thalwegs, and diminish with distance from source and lateral distance from thalweg. The model does

  3. GIS-based statistical mapping technique for block-and-ash pyroclastic flow and surge hazards

    Science.gov (United States)

    Widiwijayanti, C.; Voight, B.; Hidayat, D.; Schilling, S.

    2008-12-01

    Assessments of pyroclastic flow (PF) hazards are commonly based on mapping of PF and surge deposits and estimations of inundation limits, and/or computer models of varying degrees of sophistication. In volcanic crises a PF hazard map may be sorely needed, but limited time, exposures, or safety aspects may preclude fieldwork, and insufficient time or baseline data may be available for reliable dynamic simulations. We have developed a statistically constrained simulation model for block-and-ash PFs to estimate potential areas of inundation by adapting methodology from Iverson et al. (1998) for lahars. The predictive equations for block-and-ash PFs are calibrated with data from many volcanoes and given by A = (0.05-0.1)V2/3, B = (35-40)V2/3 , where A is cross-sectional area of inundation, B is planimetric area and V is deposit volume. The proportionality coefficients were obtained from regression analyses and comparison of simulations to mapped deposits. The method embeds the predictive equations in a GIS program coupled with DEM topography, using the LAHARZ program of Schilling (1998). Although the method is objective and reproducible, any PF hazard zone so computed should be considered as an approximate guide only, due to uncertainties on coefficients applicable to individual PFs, DEM details, and release volumes. Gradational nested hazard maps produced by these simulations reflect in a sense these uncertainties. The model does not explicitly consider dynamic behavior, which can be important. Surge impacts must be extended beyond PF hazard zones and we have explored several approaches to do this. The method has been used to supply PF hazard maps in two crises: Merapi 2006; and Montserrat 2006- 2007. We have also compared our hazard maps to actual recent PF deposits and to maps generated by several other model techniques.

  4. A numerical analysis on generating process of intermittent debris flow surges

    Science.gov (United States)

    Arai, Muneyuki

    2016-04-01

    The generation of debris flow has some causes. This researche is on intermittent debris flow surges and due to mathematical approach of wave equation by numerical analysis. The following wave equation was obtained based on the momentum equation of shallow water. ∂η' '∂η' ∂2η' ∂3η' ∂τ' + a1η ∂ξ' - a2∂ξ'2 + a3∂ξ'3 = 0 (1) where, a1 = (3/2)c0'2, a2 = (1/2)( ) 1/c0'2 - 1/2tanθ (c0'/u0'), a3 = (1/2){ 4 2 } (2 + c0')/(2c0')- 3/2 , u0' = u0/c0, c0' = c0/vp0, c0 = √ ---- gh0cosθ, η' = η/h0, t' = tvp0/h0, ξ = ɛ1/2(x- vp0t), τ = ɛ3/2t, ξ' = ξ/h0 = ɛ1/2(x' - t'), τ' = ɛ3/2t', u0, h0 : velocity, depth of steady uniform flow, x : axis of flow direction, t : time, η : variance of flow surface from depth h0, θ : slope angle of the channel, g : acceleration due to gravity, ξ, τ : the Gardner-Morikawa transformation of x axis and time, ɛ : parameter of perturbative expansion, vp0 : phase velocity, c0 : long wave velocity, '(with prime) : non-dimensional variable. η' of equation (1) changes depending on the values of a1, a2, a3 on same section of ξ' and τ', and a1, a2 and a3 are function of c0'. c0' is ratio of long wave velocity and phase velocity, and c0' = 1 when phase velocity is equal to long wave velocity. For c0' = 1, then a3 = 0, the equation (1) becomes Burgers Equation, the waves deform to a wave of wave number one with increased phase velocity on progress at time. Therefor, the wave parts from Burgers equation and becomes the one that depend on equation (1) , KdV-Burgers equation. When the new phase velocity is grater than 1.04 times c0' (long wave velocity), waveform behaves as a solitary wave. This research shows these processes by some numerical solutions of equation (1).

  5. Cold basal conditions during surges control flow of fringing Arctic ice caps in Greenland

    Science.gov (United States)

    Cook, Samuel; Christoffersen, Poul; Todd, Joe; Palmer, Steven

    2017-04-01

    Fringing ice caps separated from larger ice sheets are rarely studied, yet they are an important part of earth's cryosphere, which has become the largest source of global sea-level rise. Understanding marginal ice caps is crucial for being able to predict sea-level change as they are responsible for up to 20% of Greenland's mass loss for 2003-2008. Studies of fringing ice caps can furthermore provide useful insights into processes operating on glaciers that surge. Surging has been the focus of much recent glaciological work, especially with reference to thermal evolution of polythermal glaciers in High Mountain Asia and the High Arctic. This has shown that the classic divide between hydrologically-controlled surges ('hard-bed') in Alaska and thermally-regulated ('soft-bed') surges elsewhere is less stark than previously assumed. Studying marginal ice caps can therefore be valuable in several ways. The largest fringing ice cap in Greenland is Flade Isblink. Previous work has established that this ice cap is showing a range of dynamic behaviour, including subglacial lake drainage and varied patterns of mass-balance change. In particular, a substantial surge, assumed to be caused by a version of the thermally-regulated mechanism, occurred between 1996 and 2000, making the ice cap a useful case study for investigating this process. Here we investigate the surge on Flade Isblink using the open-source, Full-Stokes model Elmer/Ice to invert for basal conditions and englacial temperatures using the adjoint method. We specifically study steady-state conditions representative of the active surge phase in 2000, and the subsequent quiescent phase, using patterns of surface velocity observed in 2000, 2005, 2008 and 2015. Under constant geometry, temperature and geothermal heat, it is shown that surging increases basal freezing rates by over 60% across an area that is twice as large as the area over which the bed freezes in the quiescent phase. The process responsible for this

  6. Investigating controls on debris-flow initiation and surge frequency at Chalk Cliffs, USA: initial results from monitoring and modeling

    Science.gov (United States)

    Kean, J. W.; McCoy, S. W.; Tucker, G. E.; Staley, D. M.; Coe, J. A.

    2012-04-01

    Recent monitoring of a small (0.3 km2) bedrock-dominated catchment in central Colorado, USA, has revealed distinct differences in debris-flow surge dynamics relative to rainfall intensity. Moderate bursts of rainfall (15-40 mm/hr) typically trigger a set of coarse-grained surges with depths that can exceed 1.0 m. High-intensity bursts of rainfall (40-150 mm/hr), in contrast, often generate only a single moderate-amplitude coarse-grained surge (> 0.5 m depth), followed by several minutes of water-rich flow having comparable or greater peak depth. In both cases, debris flows are observed within minutes of rain bursts due to the rapid concentration of runoff from bedrock cliffs to channels loaded with sediment from dry ravel and rockfall. Video observations have shown that the runoff can initiate debris flows both at a steep (~40 degree) bedrock-colluvium interface, and in a lower gradient (~15 degree) section of channel. This latter style of initiation, which has only been observed at moderate rainfall intensity, involves the formation and failure of a highly porous sediment dam created by bedload transport. We speculate that this process may be responsible for the creation of the consistent surge patterns we observe with moderate intensity rainfall, and may explain the relative lack of granular surges with high-intensity rainfall. To investigate this possibility, we have developed a simple one-dimensional morphodynamic model of the formation and failure of sediment dams in an undulating bedrock channel filled with loose bed sediment. The model consists of a coupled surface-subsurface water flow model, which is used to drive bed-sediment topographic adjustments based on the mathematical divergence of the sediment transport rate. Under certain topographic and water-flow conditions, the shear stress in a section of the channel can fall below the critical shear stress, resulting in local deposition of sediment. Consistent with field observations, the modeled deposit

  7. Pesticide Leaching from Agricultural Fields with Ridges and Furrows

    NARCIS (Netherlands)

    Leistra, M.; Boesten, J.J.T.I.

    2010-01-01

    In the evaluation of the risk of pesticide leaching to groundwater, the soil surface is usually assumed to be level, although important crops like potato are grown on ridges. A fraction of the water from rainfall and sprinkler irrigation may flow along the soil surface from the ridges to the furrows

  8. Interrelations among pyroclastic surge, pyroclastic flow, and lahars in Smith Creek valley during first minutes of 18 May 1980 eruption of Mount St. Helens, USA

    Science.gov (United States)

    Brantley, S.R.; Waitt, R.B.

    1988-01-01

    A devastating pyroclastic surge and resultant lahars at Mount St. Helens on 18 May 1980 produced several catastrophic flowages into tributaries on the northeast volcano flank. The tributaries channeled the flows to Smith Creek valley, which lies within the area devastated by the surge but was unaffected by the great debris avalanche on the north flank. Stratigraphy shows that the pyroclastic surge preceded the lahars; there is no notable "wet" character to the surge deposits. Therefore the lahars must have originated as snowmelt, not as ejected water-saturated debris that segregated from the pyroclastic surge as has been inferred for other flanks of the volcano. In stratigraphic order the Smith Creek valley-floor materials comprise (1) a complex valley-bottom facies of the pyroclastic surge and a related pyroclastic flow, (2) an unusual hummocky diamict caused by complex mixing of lahars with the dry pyroclastic debris, and (3) deposits of secondary pyroclastic flows. These units are capped by silt containing accretionary lapilli, which began falling from a rapidly expanding mushroom-shaped cloud 20 minutes after the eruption's onset. The Smith Creek valley-bottom pyroclastic facies consists of (a) a weakly graded basal bed of fines-poor granular sand, the deposit of a low-concentration lithic pyroclastic surge, and (b) a bed of very poorly sorted pebble to cobble gravel inversely graded near its base, the deposit of a high-concentration lithic pyroclastic flow. The surge apparently segregated while crossing the steep headwater tributaries of Smith Creek; large fragments that settled from the turbulent surge formed a dense pyroclastic flow along the valley floor that lagged behind the front of the overland surge. The unusual hummocky diamict as thick as 15 m contains large lithic clasts supported by a tough, brown muddy sand matrix like that of lahar deposits upvalley. This unit contains irregular friable lenses and pods meters in diameter, blocks incorporated from

  9. Pyroclastic surges and flows from the 8-10 May 1997 explosive eruption of Bezymianny volcano, Kamchatka, Russia

    Science.gov (United States)

    Belousov, Alexander; Voight, Barry; Belousova, Marina; Petukhin, Anatoly

    2002-07-01

    The 8-10 May 1997 eruption of Bezymianny volcano began with extrusion of a crystallized plug from the vent in the upper part of the dome. Progressive gravitational collapses of the plug caused decompression of highly crystalline magma in the upper conduit, leading at 13:12 local time on 9 May to a powerful, vertical Vulcanian explosion. The dense pyroclastic mixture collapsed in boil-over style to generate a pyroclastic surge which was focused toward the southeast by the steep-walled, 1956 horseshoe-shaped crater. This surge, with a temperature 30 km2 with deposits as much as 30 cm thick and extending 7 km from the vent. The surge deposits comprised massive to vaguely laminated, gravelly sand (Md -1.2 to 3.7φ sorting 1.2 to 3φ) of poorly vesiculated andesite (mean density 1.82 g cm-3 vesicularity 30 vol% SiO2 content 58.0 wt%). The deposits, with a volume of 5-15×106 m3, became finer grained and better sorted with distance; the maximal diameter of juvenile clasts decreased from 46 to 4 cm. The transport and deposition of the surge over a snowy landscape generated extensive lahars which traveled >30 km. Immediately following the surge, semi-vesiculated block-and-ash flows were emplaced as far as 4.7 km from the vent. Over time the juvenile lava in clasts of these flows became progressively less crystallized, apparently more silicic (59.0 to 59.9 wt% SiO2) and more vesiculated (density 1.64 to 1.12 g cm-3 vesicularity 37 to 57 vol%). At this stage the eruption showed transitional behavior, with mass divided between collapsing fountain and buoyant column. The youngest pumice-and-ash flows were accompanied by a sustained sub-Plinian eruption column 14 km high, from which platy fallout clasts were deposited ( 59.7% SiO2; density 1.09 g cm-3 vesicularity 58 vol%). The explosive activity lasted about 37 min and produced a total of 0.026 km3 dense rock equivalent of magma, with an average discharge of 1.2×104 m3 s-1. A lava flow 200 m long terminated the eruption. The

  10. Winter speed-up of ice flow at quiescent surge-type glaciers in Yukon, Canada

    Science.gov (United States)

    Furuya, M.; Abe, T.

    2013-12-01

    Glacier surge exhibits order-of-magnitude faster velocity and km-scale terminus advance during its short active phase after a long quiescent period. The observations of glacier surge are still limited, and the mechanisms of glacier surge cycle remain elusive. Moreover, with the exception of several well-examined glaciers, the glacier dynamics during their quiescent periods remains even more uncertain due to the paucity of surface velocity measurement data. Here we examined spatial-temporal changes in the ice surface velocity of surge-type glaciers in the St. Elias Mountains near the border of Alaska and Yukon during the period from December 2006 to March 2011. We applied the offset-tracking (feature-tracking) technique to the L-band synthetic aperture radar (SAR) images derived from the Japanese Advanced Land Observation Satellite (ALOS). The Chitina, Anderson, Walsh, and Logan Glaciers, the major subpolar surge-type glaciers of the Chitina River valley system, could be examined with the highest temporal resolution because of the overlap of multiple satellite tracks. We have found significant upstream accelerations from fall to winter at a number of glaciers during their quiescence. Moreover, whereas the upstream propagating summer speed-up was observed, the winter speed-up propagated from upstream to downglacier. Although the winter speed-up seems to be at odds with the well-known summer speed-up, these observations are consistent with the fragmentary but well-known fact of glacier surge that often initiates in winter, suggesting that some of the mechanisms would be valid even during quiescent phases. Ice surface velocity at mountain glaciers and ice sheets typically exhibits the greatest acceleration from spring to early summer, followed by deceleration in mid-summer to fall, and is slowest in winter. These short-term velocity changes are attributed to subglacial slip associated with water pressure changes that occur because of the seasonal variability of

  11. Damage to structures by pyroclastic flows and surges, inferred from nuclear weapons effects

    Science.gov (United States)

    Valentine, Greg A.

    1998-12-01

    In order to define the risk from explosive eruptions, one must constrain both the probability of explosive events and the effects, or consequences, of those events. This paper focuses on the effects of pyroclastic flows and surges (here termed `pyroclastic density currents', or PDCs) on buildings, infrastructure elements, and to some extent on vehicles. PDCs impart a lateral force to such structures in the form of dynamic pressure, which depends on the bulk density of the PDC (which in turn depends mainly on particle concentration) and its velocity. For reasonable ranges of particle concentration (10 -3 to 0.5) and velocities (10 to 300 m/s), dynamic pressure on the upstream face of a structure ranges from ˜0.1 kPa to 10 4 kPa. Lateral loads ranging up to about 100 kPa were produced during nuclear weapons tests in the 1940s and 1950s that were designed to study the effects of such loading on a variety of structures for civil defense and emergency response purposes in the event of nuclear war. Although considerable simplifications are involved, the data from these weapon tests provide useful analog information for understanding the effects of PDCs. I reviewed data from the nuclear tests, describing the expected damage from different loadings. Tables are provided that define the response of different structural elements (e.g., windows, framing, walls) and whole structures to loading in probabilistic terms, which in principle account for variations in construction quality, orientation, and other factors. Finally, damage documented from historical eruptions at Mt. Lamington (1951), Herculaneum (AD 79 Vesuvius eruption), and St. Pierre (1902 Mt. Pelee eruption) is reviewed. Damage patterns, combined with estimates of velocity, provide an independent estimate of particle concentration in the PDCs. Details of structural damage should be recorded and mapped around future eruptions in order to help refine this aspect of consequence analysis. Another fruitful approach would

  12. Combined Wave and Surge Overtopping of Levees: Flow Hydrodynamics and Articulated Concrete Mat Stability

    Science.gov (United States)

    2008-08-01

    technical report describes small-scale physical model tests simulating combined wave and storm surge overtopping of a typical levee cross sec- tion of...journal article . The 2 percent run-up elevation should be estimated using the run-up formulas of de Waal and van der Meer (1992) or Hughes (2004). If van...to place the mats over some type of filter layer ( geotextile or stone filter) that prevents the levee or embankment soil from leeching out between

  13. Surge-type glaciers: controls, processes and distribution

    OpenAIRE

    Sevestre, Heïdi

    2015-01-01

    Glacier surging is an internally triggered instability. Surge-type glaciers periodically alternate between long periods of slow flow (the quiescent phase) and short periods of fast flow (the surge phase). Surging yields down-glacier transport of mass and often results in large and sudden glacier advances.The surging phenomenon has always challenged the notion of normality in glacier flow dynamics. The mechanisms of surging remain poorly understood. Observation of different surge behaviors acr...

  14. Coexisting state of surge and rotating stall in a two-stage axial flow compressor using a double-phase-locked averaging technique

    Science.gov (United States)

    Sakata, Yuu; Ohta, Yutaka

    2017-02-01

    The interaction between surge and rotating stall in an axial flow compressor was investigated from the viewpoint of an unsteady inner flow structure. The aim of this study was to identify the key factor that determines the switching phenomenon of a surge cycle. The main feature of the tested compressor is a shock tube connected in series to the compressor outlet through a diaphragm, slits, and a concentric duplex pipe: this system allows surge and rotating stall to be generated by connecting the shock tube with the compressor, or enables the compression plane wave injection. The unsteady characteristics and the internal flow velocity fluctuations were measured in detail, and the stall cell structure was averaged and visualized along the movement of the operation point under a coexisting state of surge. A coefficient of the cell scale fluctuation was calculated using the result of the averaging, and it confirmed that the processes of inner flow structure change differed from each other according to the next cycle of the surge. The result suggests that the key factor that determines the next cycle is the transformation of the internal flow structure, particularly between the stall cell and the entire circumferential stall, in both the recovering and stalling processes.

  15. Managing cover crops on strawberry furrow bottoms

    Science.gov (United States)

    Bare furrows in strawberry fields with plastic mulch covered beds can lead to lots of soil erosion and runoff during winter rainy periods. This article describes how growers can plant and manage cover crops in these furrows to minimize runoff and soil erosion. This is based on on-going research at...

  16. 3-D simulation of transient flow patterns in a corridor-shaped air-cushion surge chamber based on computational fluid dynamics

    Institute of Scientific and Technical Information of China (English)

    XIA Lin-sheng; CHENG Yong-guang; ZHOU Da-qing

    2013-01-01

    The 3-D characteristics of the water-air flow patterns in a corridor-shaped air-cushion surge chamber during hydraulic transients need to be considered in the shape optimization.To verify the reliability of the water-air two-phase model,namely,the volume of fluid model,the process of charging water into a closed air chamber is successfully simulated.Using the model,the 3-D flow characteristics under the load rejection and acceptance conditions within the air-cushion surge chamber of a specific hydropower station are studied.The flee surface waves,the flow patterns,and the pressure changes during the surge wave process are analyzed in detail.The longitudinal flow of water in the long corridor-shaped surge chamber is similar to the open channel flow with respect to the wave propagation,reflection and superposition characteristics.The lumped parameters of the 3-D numerical simulation agree with the results of a 1-D calculation of hydraulic transients in the whole water conveying system,which validates the 3-D method.The 3-D flow structures obtained can be applied to the shape optimization of the chamber.

  17. Generation of pyroclastic flows and surges by hot-rock avalanches from the dome of Mount St. Helens volcano, USA

    Science.gov (United States)

    Mellors, R.A.; Waitt, R.B.; Swanson, D.A.

    1988-01-01

    Several hot-rock avalanches have occurred during the growth of the composite dome of Mount St. Helens, Washington between 1980 and 1987. One of these occurred on 9 May 1986 and produced a fan-shaped avalanche deposit of juvenile dacite debris together with a more extensive pyroclastic-flow deposit. Laterally thinning deposits and abrasion and baking of wooden and plastic objects show that a hot ash-cloud surge swept beyond the limits of the pyroclastic flow. Plumes that rose 2-3 km above the dome and vitric ash that fell downwind of the volcano were also effects of this event, but no explosion occurred. All the facies observed originated from a single avalanche. Erosion and melting of craterfloor snow by the hot debris caused debris flows in the crater, and a small flood that carried juvenile and other clasts north of the crater. A second, broadly similar event occured in October 1986. Larger events of this nature could present a significant volcanic hazard. ?? 1988 Springer-Verlag.

  18. Countercurrent Flow Limitation at the Junction between the Surge Line and the Pressurizer of a PWR

    Directory of Open Access Journals (Sweden)

    Taiga Doi

    2012-01-01

    Full Text Available An experimental study on countercurrent flow limitation (CCFL in vertical pipes is carried out. Effects of upper tank geometry and water levels in the upper and lower tanks on CCFL characteristics are investigated for air-water two-phase flows at room temperature and atmospheric pressure. The following conclusions are obtained: (1 CCFL characteristics for different pipe diameters are well correlated using the Kutateladze number if the tank geometry and the water levels are the same; (2 CCFL occurs at the junction between the pipe and the upper tank both for the rectangular and cylindrical tanks, and CCFL with the cylindrical tank occurs not only at the junction but also inside the pipe at high gas flow rates and small pipe diameters; (3 the flow rate of water entering into the vertical pipe at the junction to the rectangular upper tank is lower than that to the cylindrical tank because of the presence of low frequency first-mode sloshing in the rectangular tank; (4 increases in the water level in the upper tank and in the air volume in the lower tank increase water penetration into the pipe, and therefore, they mitigate the flow limitation.

  19. Combined effects of projected sea level rise, storm surge, and peak river flows on water levels in the Skagit Floodplain

    Science.gov (United States)

    Hamman, Josheph J; Hamlet, Alan F.; Fuller, Roger; Grossman, Eric

    2016-01-01

    Current understanding of the combined effects of sea level rise (SLR), storm surge, and changes in river flooding on near-coastal environments is very limited. This project uses a suite of numerical models to examine the combined effects of projected future climate change on flooding in the Skagit floodplain and estuary. Statistically and dynamically downscaled global climate model scenarios from the ECHAM-5 GCM were used as the climate forcings. Unregulated daily river flows were simulated using the VIC hydrology model, and regulated river flows were simulated using the SkagitSim reservoir operations model. Daily tidal anomalies (TA) were calculated using a regression approach based on ENSO and atmospheric pressure forcing simulated by the WRF regional climate model. A 2-D hydrodynamic model was used to estimate water surface elevations in the Skagit floodplain using resampled hourly hydrographs keyed to regulated daily flood flows produced by the reservoir simulation model, and tide predictions adjusted for SLR and TA. Combining peak annual TA with projected sea level rise, the historical (1970–1999) 100-yr peak high water level is exceeded essentially every year by the 2050s. The combination of projected sea level rise and larger floods by the 2080s yields both increased flood inundation area (+ 74%), and increased average water depth (+ 25 cm) in the Skagit floodplain during a 100-year flood. Adding sea level rise to the historical FEMA 100-year flood resulted in a 35% increase in inundation area by the 2040's, compared to a 57% increase when both SLR and projected changes in river flow were combined.

  20. A New Model for Predicting Dynamic Surge Pressure in Gas and Drilling Mud Two-Phase Flow during Tripping Operations

    Directory of Open Access Journals (Sweden)

    Xiangwei Kong

    2014-01-01

    Full Text Available Investigation of surge pressure is of great significance to the circulation loss problem caused by unsteady operations in management pressure drilling (MPD operations. With full consideration of the important factors such as wave velocity, gas influx rate, pressure, temperature, and well depth, a new surge pressure model has been proposed based on the mass conservation equations and the momentum conservation equations during MPD operations. The finite-difference method, the Newton-Raphson iterative method, and the fourth-order explicit Runge-Kutta method (R-K4 are adopted to solve the model. Calculation results indicate that the surge pressure has different values with respect to different drill pipe tripping speeds and well parameters. In general, the surge pressure tends to increase with the increases of drill pipe operating speed and with the decrease of gas influx rate and wellbore diameter. When the gas influx occurs, the surge pressure is weakened obviously. The surge pressure can cause a significant lag time if the gas influx occurs at bottomhole, and it is mainly affected by pressure wave velocity. The maximum surge pressure may occur before drill pipe reaches bottomhole, and the surge pressure is mainly affected by drill pipe operating speed and gas influx rate.

  1. Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates

    NARCIS (Netherlands)

    Percin, M.; Van Oudheusden, B.W.

    2015-01-01

    Tomographic particle image velocimetry was used to explore the evolution of three-dimensional flow structures of revolving low-aspect-ratio flat plates in combination with force measurements at a Reynolds number of 10,000. Two motion kinematics are compared that result in the same terminal condition

  2. Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates

    NARCIS (Netherlands)

    Percin, M.; Van Oudheusden, B.W.

    2015-01-01

    Tomographic particle image velocimetry was used to explore the evolution of three-dimensional flow structures of revolving low-aspect-ratio flat plates in combination with force measurements at a Reynolds number of 10,000. Two motion kinematics are compared that result in the same terminal condition

  3. Heterogeneity in Karakoram glacier surges

    Science.gov (United States)

    Quincey, Duncan J.; Glasser, Neil F.; Cook, Simon J.; Luckman, Adrian

    2015-07-01

    Many Karakoram glaciers periodically undergo surges during which large volumes of ice and debris are rapidly transported downglacier, usually at a rate of 1-2 orders of magnitude greater than during quiescence. Here we identify eight recent surges in the region and map their surface velocities using cross-correlation feature tracking on optical satellite imagery. In total, we present 44 surface velocity data sets, which show that Karakoram surges are generally short-lived, lasting between 3 and 5 years in most cases, and have rapid buildup and relaxation phases, often lasting less than a year. Peak velocities of up to 2 km a-1 are reached during summer months, and the surges tend to diminish during winter months. Otherwise, they do not follow a clearly identifiable pattern. In two of the surges, the peak velocity travels down-ice through time as a wave, which we interpret as a surge front. Three other surges are characterized by high velocities that occur simultaneously across the entire glacier surface, and acceleration and deceleration are close to monotonic. There is also no consistent seasonal control on surge initiation or termination. We suggest that the differing styles of surge can be partly accounted for by individual glacier configurations and that while some characteristics of Karakoram surges are akin to thermally controlled surges elsewhere (e.g., Svalbard), the dominant surge mechanism remains unclear. We thus propose that these surges represent a spectrum of flow instabilities and the processes controlling their evolution may vary on a glacier by glacier basis.

  4. Revealing glacier flow and surge dynamics from animated satellite image sequences: examples from the Karakoram

    OpenAIRE

    Paul, F

    2015-01-01

    Although animated images are very popular on the internet, they have so far found only limited use for glaciological applications. With long time series of satellite images becoming increasingly available and glaciers being well recognized for their rapid changes and variable flow dynamics, animated sequences of multiple satellite images reveal glacier dynamics in a time-lapse mode, making the otherwise slow changes of glacier movement visible and understandable to the wider...

  5. Analytical Calculation of Stall-inception and Surge Points for an Axial-flow Compresor Rotor

    OpenAIRE

    Moreno Benavides, Efren; López Juste, Gregorio

    2012-01-01

    Recently, a theoretical criterion to calculate the stability of an axial-flow compressor rotor has been presented in the scientific literature. This theoretical criterion was used for determining the locus of the stability line over the rotor map and for predicting the post-stall evolution of the constant-speed line of a rotor. The main objective of this paper is to improve the predictions of such a model. To do that, the paper proposes a different characterization of the characteristic az...

  6. Effect of infiltration modeling approach on operational solutions for furrow irrigation

    Science.gov (United States)

    Infiltration in irrigated furrows depends on the variation of depth of flow and, thus, wetted perimeter along the field and in time. However, the magnitude of the wetted perimeter effect has not been clearly established due to soil variability, erosion and deposition, macropore flow, and other proc...

  7. Furrow-irrigated chufa crops in Valencia (Spain. II: Performance analysis and optimization

    Directory of Open Access Journals (Sweden)

    N. Pascual-Seva

    2013-01-01

    Full Text Available Chufa (Cyperus esculentus L. var. sativus Boeck. is a traditional crop in the Mediterranean region of Spain, where it is only furrow irrigated. This article analyzes the irrigation performance for this crop, conducting field studies over three consecutive seasons in Valencia (Spain. Irrigation schedule was based on the volumetric soil water content, which was measured with capacitance sensors. Infiltrability was measured with blocked-furrow infiltrometers. An area velocity flow module measured the water flow, the cross-sectional geometry of furrows was determined using furrow profilometers, and times for advance and recession were recorded. WinSRFR software was used to analyze every irrigation event, determining the application efficiency (AE and distribution uniformity of the minimum (DUmin, and to optimize the combination of furrow inflow (q and cut-off time (Tco. Average values obtained for AE were 30.1%, 25.6%, and 26.7% in 2007, 2008, and 2009, respectively, and the corresponding DUmin values were 0.54, 0.61, and 0.67. Optimized results showed that it is possible to reach AE and DUmin values up to 87% and 0.86, respectively. However, understanding the q-Tco relationship that maximizes both AE and DUmin is more important than knowing the specific values. A function that related q and Tco was obtained for the typical plot dimensions, and this was validated in 2011. Therefore, this function can be used in most of the plots in the cultivation area.

  8. Inland-directed base surge generated by the explosive interaction of pyroclastic flows and seawater at Soufrière Hills volcano, Montserrat

    Science.gov (United States)

    Edmonds, Marie; Herd, Richard A.

    2005-01-01

    The largest and most intense lava-dome collapse during the eruption of Soufrière Hills volcano, Montserrat, 1995–2004, occurred 12–13 July 2003. The dome collapse involved around 200 × 106 m3 of material and was associated with a phenomenon previously unknown at this volcano. Large pyroclastic flows at the peak of the dome collapse interacted explosively with seawater at the mouth of the Tar River Valley and generated a hot, dry base surge that flowed 4 km inland and 300 m uphill. The surge was destructive to at least 25 m above the ground and it carbonized vegetation. The resulting two-layer deposits were as much as 0.9 m thick. Although the entire collapse lasted 18 h, the base surge greatly increased the land area affected by the dome collapse in a few minutes at the peak of the event, illustrating the complex nature of the interaction between pyroclastic flows and seawater.

  9. Phosphorus losses in furrow irrigation runoff.

    Science.gov (United States)

    Westermann, D T; Bjorneberg, D L; Aase, J K; Robbins, C W

    2001-01-01

    Phosphorus (P) often limits the eutrophication of streams, rivers, and lakes receiving surface runoff. We evaluated the relationships among selected soil P availability indices and runoff P fractions where manure, whey, or commercial fertilizer applications had previously established a range of soil P availabilities on a Portneuf silt loam (coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid) surface-irrigated with Snake River water. Water-soluble P, Olsen P (inorganic and organic P), and iron-oxide impregnated paper-extractable P (FeO-Ps) were determined on a 0.03-m soil sample taken from the bottom of each furrow before each irrigation in fall 1998 and spring 1999. Dissolved reactive phosphorus (DRP) in a 0.45-microm filtered runoff sample, and iron-oxide impregnated paper-extractable P (FeO-Pw), total P, and sediment in an unfiltered runoff sample were determined at selected intervals during a 4-h irrigation on 18.3-m field plots. The 1998 and 1999 data sets were combined because there were no significant differences. Flow-weighted average runoff DRP and FeO-Pw concentrations increased linearly as all three soil P test concentrations increased. The average runoff total P concentration was not related to any soil P test but was linearly related to sediment concentration. Stepwise regression selected the independent variables of sediment, soil lime concentration, and soil organic P extracted by the Olsen method as related to average runoff total P concentration. The average runoff total P concentration was 1.08 mg L(-1) at a soil Olsen P concentration of 10 mg kg(-1). Soil erosion control will be necessary to reduce P losses in surface irrigation runoff.

  10. Granulocyte-Colony Stimulating Factor Increases Cerebral Blood Flow via a NO Surge Mediated by Akt/eNOS Pathway to Reduce Ischemic Injury

    Directory of Open Access Journals (Sweden)

    Hock-Kean Liew

    2015-01-01

    Full Text Available Granulocyte-colony stimulating factor (G-CSF protects brain from ischemic/reperfusion (I/R injury, and inhibition of nitric oxide (NO synthases partially reduces G-CSF protection. We thus further investigated the effects of G-CSF on ischemia-induced NO production and its consequence on regional cerebral blood flow (rCBF and neurological deficit. Endothelin-1 (ET-1 microinfused above middle cerebral artery caused a rapid reduction of rCBF (ischemia which lasted for 30 minutes and was followed by a gradual recovery of blood flow (reperfusion within the striatal region. Regional NO concentration increased rapidly (NO surge during ischemia and recovered soon to the baseline. G-CSF increased rCBF resulting in shorter ischemic duration and an earlier onset of reperfusion. The enhancement of the ischemia-induced NO by G-CSF accompanied by elevation of phospho-Akt and phospho-eNOS was noted, suggesting an activation of Akt/eNOS. I/R-induced infarct volume and neurological deficits were also reduced by G-CSF treatment. Inhibition of NO synthesis by L-NG-Nitroarginine Methyl Ester (L-NAME significantly reduced the effects of G-CSF on rCBF, NO surge, infarct volume, and neurological deficits. We conclude that G-CSF increases rCBF through a NO surge mediated by Akt/eNOS, which partially contributes to the beneficial effect of G-CSF on brain I/R injury.

  11. Validation of a surge model by full scale testing

    NARCIS (Netherlands)

    Slot, H.J.; Meulendijks, D.; Smeulers, J.P.M.

    2009-01-01

    Surge of turbo compressors can cause large stepwise changes in flow and pressure, which can potentially damage the compressor and any equipment that is in direct connection with the compressor. Surge is usually avoided by an anti surge controller (ASC). However, in spite of the ASC surge cycles may

  12. Validation of a surge model by full scale testing

    NARCIS (Netherlands)

    Smeulers, J.P.M.; Slot, H.J.; Meulendijks, D.

    2011-01-01

    Surge of turbo compressors can cause large stepwise changes in flow and pressure, which can potentially damage the compressor and any equipment that is in direct connection with the compressor. Surge is usually avoided by an anti surge controller (ASC). However, in spite of the ASC surge cycles may

  13. Svalbard surging glacier landsystems

    Science.gov (United States)

    Lovell, Harold; Benn, Douglas; Lukas, Sven; Flink, Anne

    2014-05-01

    The percentage of Svalbard glaciers thought to be of surge-type is somewhere between 13-90% according to different sources variously based on statistical analysis and observations of diagnostic glaciological and geomorphological features, e.g. looped moraines. Developing a better understanding of which of these figures, if either, is most realistic is important in the context of glacier dynamics and related contributions of small glaciers and ice caps to sea level change in the immediate future. We present detailed geomorphological assessments of the margins of several known surge-type glaciers in Svalbard in order to update and improve the existing framework by which they are identified, and to provide a foundation for future reassessments of the surge-type glacier population based on distinct landform-sediment assemblages. Three landsystems are proposed: (1) Surges of small valley glaciers produce a prominent ice-cored latero-frontal moraine at their surge maximum and are characterised by an inner zone of ice stagnation terrain (hummocky topography, kettle lakes, debris flows) with no or only very few poorly-defined bedforms (crevasse squeeze ridges, eskers and flutes) and no recessional moraines. Many of these glaciers may have surged in the past but show no signs that they have the capability to do so again in the future. (2) Larger land-terminating glaciers, often with several tributaries, typically produce a push moraine complex which contains evidence for multiple advances, as identified from ridge-meltwater channel relationships. The inner zone often contains a large lagoon, partly dammed by the push moraine complex, and widespread ice stagnation terrain. Crevasse squeeze ridges, eskers and flutes are well-defined but small and limited in number and distribution. (3) Surges of large tidewater glaciers produce distinctive, often multi-generational, landform assemblages both in submarine and lateral terrestrial positions. The well-preserved submarine record

  14. Use of Mobile Pipeline with Self-regulated Water Outlets for Furrow Irrigation

    Directory of Open Access Journals (Sweden)

    Vysochkina L.I.

    2016-03-01

    Full Text Available Surface irrigation is one of the most common irrigation methods, but it has its own significant drawbacks. A mobile pipeline for furrow irrigation from closed irrigation network was designed and its parameters were proved in order to improve furrow irrigation. The mobile pipeline consists of plastic pipes based on 10 pairs of spring skis connected in the middle by a flexible connection. It is known that water flow into the furrow decreases along the pipeline due to pressure losses along the length of the pipeline. It was proposed to use water outlets ensuring uniform supply of water to each furrow by the presence of the butterfly valve in housing of the water outlet in the mobile pipeline. In order to ensure sustainable valve position, an equation was derived and values of the area of the upper and bottom parts of the valve were obtained. According to the pipeline field test results, water distribution uniformity coefficient through the outlets was 0.98, at a flow rate of 1.0-3.0 l∙s-1 and hydraulic slopes along the pipeline of 0.001−0.005.

  15. Soil Water Distribution and Irrigation Uniformity Under Alternative Furrow Irrigation

    Institute of Scientific and Technical Information of China (English)

    PAN Ying-hua; KANG Shao-zhong; DU Tai-sheng; YANG Xiu-ying

    2003-01-01

    Field experiments were conducted to investigate the spatial-temporal distribution and the uni-formity of soil water under alternative furrow irrigation in spring maize field in Gansu Province. Resultsshowed that during the crop growing season, alternative drying and wetting furrows could incur crops to en-dure a water stress, thus the adsorptive ability of root system could be enhanced. As there was no zero fluxplane between irrigated furrows and non-irrigated furrows under alternative furrow irrigation, lateral infiltra-tion of water was obviously increased, thus decreasing the deep percolation. Compared with the conventionalirrigation, although the water consumption in alternative furrow irrigation was reduced, the uniformity of soilwater was not obviously affected.

  16. Modeling and Controlling Flow Transient in Pipeline Systems: Applied for Reservoir and Pump Systems Combined with Simple Surge Tank

    Directory of Open Access Journals (Sweden)

    Itissam ABUIZIAH

    2014-03-01

    Full Text Available When transient conditions (water hammer exist, the life expectancy of the system can be adversely impacted, resulting in pump and valve failures and catastrophic pipe rupture. Hence, transient control has become an essential requirement for ensuring safe operation of water pipeline systems. To protect the pipeline systems from transient effects, an accurate analysis and suitable protection devices should be used. This paper presents the problem of modeling and simulation of transient phenomena in hydraulic systems based on the characteristics method. Also, it provides the influence of using the protection devices to control the adverse effects due to excessive and low pressure occuring in the transient. We applied this model for two main pipeline systems: Valve and pump combined with a simple surge tank connected to reservoir. The results obtained by using this model indicate that the model is an efficient tool for water hammer analysis. Moreover, using a simple surge tank reduces the unfavorable effects of transients by reducing pressure fluctuations.

  17. Role of the furrow of the proximal colon in the production of soft and hard feces in nutrias, Myocastor coypus.

    Science.gov (United States)

    Takahashi, T; Sakaguchi, E

    2000-11-01

    The bacterial level of soft feces is higher than that of hard feces in nutrias. This suggests the heterogeneity of bacterial density in the large intestine. To show the heterogeneity of bacteria in the contents of the large intestine in nutrias, we divided the contents of the large intestine into 12 regions, then measured the nitrogen (N), total amino acids (TAA) and diaminopimelic acid (DAP), a bacterial marker, of these regions. Levels of N, TAA and DAP varied along the cross section of the proximal colon. The greater curvature of the main lumen and furrow had higher N, TAA and DAP concentrations than the lesser curvature. We also examined the involvement of the furrow in producing two types of feces differing in bacterial nitrogen content by surgically preventing the flow of the furrow contents. We compared the concentrations of N, TAA and DAP between soft and hard feces among operated, sham-operated and intact animals. Surgical closure of the furrow abolished the difference in levels of N, TAA and DAP between soft and hard feces, suggesting that the furrow of the proximal colon is responsible for making the bacterial density higher in soft feces than in hard feces.

  18. Conjunctival intraepithelial neoplasia with corneal furrow degeneration

    Directory of Open Access Journals (Sweden)

    Pukhraj Rishi

    2014-01-01

    Full Text Available A 68-year-old man presented with redness of left eye since six months. Examination revealed bilateral corneal furrow degeneration. Left eye lesion was suggestive of conjunctival squamous cell carcinoma, encroaching on to cornea. Anterior segment optical coherence tomography (AS-OCT confirmed peripheral corneal thinning. Fluorescein angiography confirmed intrinsic vascularity of lesion. Patient was managed with "no touch" surgical excision, dry keratectomy without alcohol, cryotherapy, and primary closure. Pathologic examination of removed tissue confirmed clinical diagnosis. Management of this particular case required modification of standard treatment protocol. Unlike the alcohol-assisted technique of tumor dissection described, ethyl alcohol was not used for risk of corneal perforation due to underlying peripheral corneal thinning. Likewise, topical steroids were withheld in the post-operative period. Three weeks post-operatively, left eye was healing well. Hence, per-operative usage of absolute alcohol and post-operative use of topical steroids may be best avoided in such eyes.

  19. Mitochondria localize to the cleavage furrow in mammalian cytokinesis.

    Science.gov (United States)

    Lawrence, Elizabeth J; Mandato, Craig A

    2013-01-01

    Mitochondria are dynamic organelles with multiple cellular functions, including ATP production, calcium buffering, and lipid biosynthesis. Several studies have shown that mitochondrial positioning is regulated by the cytoskeleton during cell division in several eukaryotic systems. However, the distribution of mitochondria during mammalian cytokinesis and whether the distribution is regulated by the cytoskeleton has not been examined. Using live spinning disk confocal microscopy and quantitative analysis of mitochondrial fluorescence intensity, we demonstrate that mitochondria are recruited to the cleavage furrow during cytokinesis in HeLa cells. After anaphase onset, the mitochondria are recruited towards the site of cleavage furrow formation, where they remain enriched as the furrow ingresses and until cytokinesis completion. Furthermore, we show that recruitment of mitochondria to the furrow occurs in multiple mammalian cells lines as well as in monopolar, bipolar, and multipolar divisions, suggesting that the mechanism of recruitment is conserved and robust. Using inhibitors of cytoskeleton dynamics, we show that the microtubule cytoskeleton, but not actin, is required to transport mitochondria to the cleavage furrow. Thus, mitochondria are specifically recruited to the cleavage furrow in a microtubule-dependent manner during mammalian cytokinesis. Two possible reasons for this could be to localize mitochondrial function to the furrow to facilitate cytokinesis and / or ensure accurate mitochondrial inheritance.

  20. Measurement of the filling height of transient two-phase surge flows in pipelines by means of electronics; Messung der Fuellhoehe von transienten Zweiphasenschwallstroemungen in Rohrleitungen mittels Ultraschall

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, B.; Rockstroh, M. [Technische Univ. Dresden (Germany). Inst. fuer Energiemaschinen und Maschinenlabor

    1997-12-01

    The aim of the ultrasonic measurements was the determination of the time course of the level of a transient surge flow with swirl and waves in partly filled roughly horizontally laid pipelines. The running time of the ultrasonic waves from the test head to the liquid surface and back was measured for this purpose. The course of the stress was recorded digitally and was evaluated with the aid of software. Waves, swirl, turbulence of flow and introduced test bodies in the flow caused typical echoes, which had to be taken into account in the evaluation. As the test head was fitted on the outside of the pipe (clamp-on technique), the pipe wall thickness and the speed of sound in the pipe wall had to be included in the calculation of filling height by means of a correction. [Deutsch] Ziel der Ultraschallmessungen war die Bestimmung des zeitlichen Verlaufes der Fuellhoehe einer transienten, drall- und wellenbehafteten Schwallstroemung in teilgefuellten, etwa horizontal verlegten Rohrleitungen. Hierzu wurde die Laufzeit der Ultraschallwellen vom Pruefkopf zur Fluessigkeitsoberflaeche und zurueck gemessen. Die Laufzeit der Ultraschallwellen wurde auf eine quasi-analog elektrische Spannung abgebildet. Der Spannungsverlauf wurde digital aufgezeichnet und softwaregestuetzt ausgewertet. Wellen, Drall, Stroemungsturbulenzen sowie eingebrachte Pruefkoerper in der Stroemung hatten typische Echoerscheinungen zur Folge, die bei der Auswertung zu beruecksichtigen waren. Da der Pruefkopf aussen am Rohr angebracht war (clamp-on-Technik), musste die Rohrwandstaerke und die Schallgeschwindigkeit in der Rohrwandung mittels eines Korrekturgliedes in die Fuellhoehenberechnung eingezogen werden. (orig.)

  1. Validation of a surge model by full scale testing

    NARCIS (Netherlands)

    Smeulers, J.P.M.; Gonzalez Díez, N.; Slot, H.J.

    2012-01-01

    Surge of turbo compressors can cause large almost step like changes in flow and pressure, which can potentially damage the compressor and any equipment that is in direct connection with the compressor. In spite of an anti-surge controller (ASC), at extreme events surge cycles may occur. In order to

  2. Inoculation of maize with Azospirillum brasilense in the seed furrow

    OpenAIRE

    Tâmara Prado de Morais; Césio Humberto de Brito; Afonso Maria Brandão; Wender Santos Rezende

    2016-01-01

    ABSTRACT Several studies addressing the inoculation of cereals with diazotrophic microorganisms can be found in the literature. However, in many experiments, investigators have overlooked the feasibility of applying these microorganisms to the furrow together with the seed, and the effect of bacterial concentration on phytostimulation. The aim of this work was to evaluate the effect of doses of an inoculant based on Azospirillum brasilense, applied to the seed furrow when planting maize, comb...

  3. Space-time principles of reducing stripping in furrow pits

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The lower slope of furrow pits has following special features: small extent of weathering destruction, short time of production blasting damage, good arching effect of lower slope with small curvature radius, and good bottom effect ofa pit end for transferring and bearing initial horizontal stresses in lower slope. The new principles provided theoretical basis for convex slope in furrow pits to reduce stripping. Similar phenomena and examples are supplied simultaneously.

  4. A vertex model of Drosophila ventral furrow formation.

    Directory of Open Access Journals (Sweden)

    Philipp Spahn

    Full Text Available Ventral furrow formation in Drosophila is an outstanding model system to study the mechanisms involved in large-scale tissue rearrangements. Ventral cells accumulate myosin at their apical sides and, while being tightly coupled to each other via apical adherens junctions, execute actomyosin contractions that lead to reduction of their apical cell surface. Thereby, a band of constricted cells along the ventral epithelium emerges which will form a tissue indentation along the ventral midline (the ventral furrow. Here we adopt a 2D vertex model to simulate ventral furrow formation in a surface view allowing easy comparison with confocal live-recordings. We show that in order to reproduce furrow morphology seen in vivo, a gradient of contractility must be assumed in the ventral epithelium which renders cells more contractile the closer they lie to the ventral midline. The model predicts previous experimental findings, such as the gain of eccentric morphology of constricting cells and an incremental fashion of apical cell area reduction. Analysis of the model suggests that this incremental area reduction is caused by the dynamical interplay of cell elasticity and stochastic contractility as well as by the opposing forces from contracting neighbour cells. We underpin results from the model through in vivo analysis of ventral furrow formation in wildtype and twi mutant embryos. Our results show that ventral furrow formation can be accomplished as a "tug-of-war" between stochastically contracting, mechanically coupled cells and may require less rigorous regulation than previously thought.For the developmental biologist it is a fascinating question how cells can coordinate major tissue movements during embryonic development. The so-called ventral furrow of the Drosophila embryo is a well-studied example of such a process when cells from a ventral band, spanning nearly the entire length of the embryo, undergo dramatic shape change by contracting their

  5. Residuejams and their effect on Infiltration, Runoff and Dissolved Organic Carbon (DOC) in Furrow Irrigation Systems

    Science.gov (United States)

    Mailapalli, D. R.; Wallender, W. W.; Horwath, W.; Ma, S.; Lazicki, P.

    2007-12-01

    Crop residue, which consists of small debris of different sizes, is an important resource in agricultural ecosystems. It plays a vital role in conservation tillage as a best management practice (BMP) for reducing runoff, sediment, nutrient and pesticide transport from irrigated fields. In furrow irrigation, the predominant irrigation method in the world, as irrigation or winter runoff water moves along a furrow, it lifts the unanchored residue and transports across the field. The complex interaction of multiple residue pieces (debris) with itself, the soil matrix, and the fluid cause jams to form along the furrow. The residuejams can be thought of logjams in fluvial rivers or channels which help in increasing channel roughness to reduce flow velocities and shear stress along eroding banks. The logjams also create a hydraulic shadow, a low-velocity zone for some distance upstream that allows sediment to settle out and stabilize. Similarly, the residuejams help in formation of catchments, which promote increased infiltration and settlement of sediments along the furrow. The infiltration and residue interaction with the soil-water influence the runoff, sediment, nutrient and dissolved organic carbon (DOC) export. The reduction of DOC export is critical to enhancing drinking water resources by reducing reactive sources of DOC that form carcinogenic by-products in the disinfection process. Hence, investigation of geomorphology of the residuejams is essential to understand their impact on infiltration, runoff and DOC concentration. This study focuses on the formation of residuejams and their effect on the infiltration, runoff and DOC concentration from 122 m long furrow plots with cover crop (CC), no-till (NT) and standard tillage (ST). These treatments (CC, NT and ST) were replicated three times using randomized complete block design and the plots initially, had 10, 32 and 42% of residue cover (sunflower residue on ST and NT; sunflower and wheat residue on CC plot

  6. Draft tube discharge fluctuation during self-sustained pressure surge: fluorescent particle image velocimetry in two-phase flow

    Science.gov (United States)

    Müller, A.; Dreyer, M.; Andreini, N.; Avellan, F.

    2013-04-01

    Hydraulic machines play an increasingly important role in providing a secondary energy reserve for the integration of renewable energy sources in the existing power grid. This requires a significant extension of their usual operating range, involving the presence of cavitating flow regimes in the draft tube. At overload conditions, the self-sustained oscillation of a large cavity at the runner outlet, called vortex rope, generates violent periodic pressure pulsations. In an effort to better understand the nature of this unstable behavior and its interaction with the surrounding hydraulic and mechanical system, the flow leaving the runner is investigated by means of particle image velocimetry. The measurements are performed in the draft tube cone of a reduced scale model of a Francis turbine. A cost-effective method for the in-house production of fluorescent seeding material is developed and described, based on off-the-shelf polyamide particles and Rhodamine B dye. Velocity profiles are obtained at three streamwise positions in the draft tube cone, and the corresponding discharge variation in presence of the vortex rope is calculated. The results suggest that 5-10 % of the discharge in the draft tube cone is passing inside the vortex rope.

  7. Surge Driven Return Flow Results in Deposition of Coarse Grain Horizons Archiving a 4000 Year Record of Extreme Storm Events, Cape Cod, Massachusetts

    Science.gov (United States)

    Maio, C. V.; Donnelly, J. P.; Sullivan, R.; Weidman, C. R.; Sheremet, V.

    2014-12-01

    The brevity of the instrumental record and lack of detailed historical accounts is a limiting factor in our understanding of the relationship between climate change and the frequency and intensity of extreme storm events. This study applied paleotempestologic and hydrographic methods to identify the mechanisms of storm-induced coarse grain deposition and reconstruct a late Holocene storm record within Waquoit Bay, Massachusetts. Three sediment cores (6.0 m, 8.4 m, and 8.2 m) were collected in 3 m of water using a vibracore system. Grain sizes were measured along core to identify coarse grain anomalies that serve as a proxy for past storm events. An historical age model (1620-2011 AD) was developed based on Pb pollution chronomarkers derived from X-Ray Florescence bulk Pb data, equating to a sedimentation rate of 8-8.3 mm/yr (R2 = 0.99). A long-term (4000 to 275 years before present) sedimentation rate of 1.1-1.4 mm/yr (R2 = 0.89) was calculated based on twenty-four continuous flow atomic mass spectrometry 14C ages of marine bivalves. To determine hydrographic conditions within the embayment during storm events current meters and tide gauges were deployed during Hurricane Irene (2011) which measured a storm surge of 88 cm above mean sea level. The buildup of storm water against the landward shoreline resulted in a measured 10 cm/s seaward moving bottom current capable of transporting coarse sand eroded from the adjacent shoreface into the coring site. Modeled surges for eleven modern and historic storm events ranged in height from 0.37 m (2011) to 3.72 m (1635) above mean high water. The WAQ1, WAQ2, and WAQ3 cores recorded a total of 89, 139, and 137 positive anomalies that exceeded the lower threshold and 15, 34, and 12 that exceeded the upper threshold respectively. Events recorded during the historic period coincide with documented storm events. The mean frequency within the three cores applying the lower threshold was 2.6 events per century, while applying the

  8. Emergency department surge capacity: recommendations of the Australasian Surge Strategy Working Group.

    Science.gov (United States)

    Bradt, David A; Aitken, Peter; Fitzgerald, Gerry; Swift, Roger; O'Reilly, Gerard; Bartley, Bruce

    2009-12-01

    For more than a decade, emergency medicine (EM) organizations have produced guidelines, training, and leadership for disaster management. However, to date there have been limited guidelines for emergency physicians (EPs) needing to provide a rapid response to a surge in demand. The aim of this project was to identify strategies that may guide surge management in the emergency department (ED). A working group of individuals experienced in disaster medicine from the Australasian College for Emergency Medicine Disaster Medicine Subcommittee (the Australasian Surge Strategy Working Group) was established to undertake this work. The Working Group used a modified Delphi technique to examine response actions in surge situations and identified underlying assumptions from disaster epidemiology and clinical practice. The group then characterized surge strategies from their corpus of experience; examined them through available relevant published literature; and collated these within domains of space, staff, supplies, and system operations. These recommendations detail 22 potential actions available to an EP working in the context of surge, along with detailed guidance on surge recognition, triage, patient flow through the ED, and clinical goals and practices. The article also identifies areas that merit future research, including the measurement of surge capacity, constraints to strategy implementation, validation of surge strategies, and measurement of strategy impacts on throughput, cost, and quality of care.

  9. Function and dynamics of slam in furrow formation in early Drosophila embryo.

    Science.gov (United States)

    Acharya, Sreemukta; Laupsien, Philip; Wenzl, Christian; Yan, Shuling; Großhans, Jörg

    2014-02-15

    The Drosophila embryo undergoes a developmental transition in the blastoderm stage switching from syncytial to cellular development. The cleavage furrow, which encloses nuclei into cells, is a prominent morphological feature of this transition. It is not clear how the pattern of the furrow array is defined and how zygotic genes trigger the formation and invagination of interphase furrows. A key to these questions is provided by the gene slam, which has been previously implicated in controlling furrow invagination. Here we investigate the null phenotype of slam, the dynamics of Slam protein, and its control by the recycling endosome. We find that slam is essential for furrow invagination during cellularisation and together with nullo, for specification of the furrow. During cellularisation, Slam marks first the furrow, which is derived from the metaphase furrow of the previous mitosis. Slightly later, Slam accumulates at new furrows between daughter cells early in interphase. Slam is stably associated with the furrow canal except for the onset of cellularisation as revealed by FRAP experiments. Restriction of Slam to the furrow canal and Slam mobility during cellularisation is controlled by the recycling endosome and centrosomes. We propose a three step model. The retracting metaphase furrow leaves an initial mark. This mark and the border between corresponding daughter nuclei are refined by vesicular transport away from pericentrosomal recycling endosome towards the margins of the somatic buds. Following the onset of zygotic gene expression, Slam and Nullo together stabilise this mark and Slam triggers invagination of the cleavage furrow.

  10. Nitrogen Effects on Onion Yield Under Drip and Furrow Irrigation

    Science.gov (United States)

    Onion (Allium cepa L.) is a high cash value crop with a very shallow root system that is frequently irrigated and fertilized with high N rates to maximize yield. Converting from furrow-irrigated to drip-irrigated onion production may reduce N fertilizer needs, water inputs, and NO3-N leaching poten...

  11. Inoculation of maize with Azospirillum brasilense in the seed furrow

    Directory of Open Access Journals (Sweden)

    Tâmara Prado de Morais

    2016-06-01

    Full Text Available ABSTRACT Several studies addressing the inoculation of cereals with diazotrophic microorganisms can be found in the literature. However, in many experiments, investigators have overlooked the feasibility of applying these microorganisms to the furrow together with the seed, and the effect of bacterial concentration on phytostimulation. The aim of this work was to evaluate the effect of doses of an inoculant based on Azospirillum brasilense, applied to the seed furrow when planting maize, combined with different doses of nitrogen fertiliser. The experiment was carried out in the field, in soil of the cerrado region of Brazil. An experimental design of randomised blocks in bands was adopted, comprising nitrogen (40, 100, 200 and 300 kg ha-1 and doses of an A. brasilense-based liquid inoculant applied to the seed furrow (0, 100, 200, 300 and 400 mL ha-1. The dose of 200 mL ha-1Azospirillum was noteworthy for grain production. This is the first report of the effective application of Azospirillum in the seed furrow when planting maize in the cerrado region of Brazil.

  12. Wetted-perimeter dependent furrow infiltration and its implication for the hydraulic analysis of furrow irrigation systems

    Science.gov (United States)

    This article discusses a methodology, derived from the two-dimensional Richards equation, for estimating furrow infiltration. The method was originally derived assuming a constant pressure head at the infiltrating surface. Application of the methodology to cases where the pressure head is variable ...

  13. Measuring and modeling two-dimensional irrigation infiltration under film-mulched furrows

    Institute of Scientific and Technical Information of China (English)

    YongYong Zhang; PuTe Wu; XiNing Zhao; WenZhi Zhao

    2016-01-01

    Furrow irrigation with film-mulched agricultural beds is being promoted in the arid region of northwest China because it improves water utilization. Two-dimensional infiltration patterns under film-mulched furrows can provide guidelines and criteria for irrigation design and operation. Our objective was to investigate soil water dynamics during ponding irrigation infiltration of mulched furrows in a cross-sectional ridge-furrow configuration, using laboratory experiments and math-ematical simulations. Six experimental treatments, with two soil types (silt loam and sandy loam), were investigated to monitor the wetting patterns and soil water distribution in a cuboid soil chamber. Irrigation of mulched furrows clearly increased water lateral infiltration on ridge shoulders and ridges, due to enhancement of capillary driving force. Increases to both initial soil water content (SWC) and irrigation water level resulted in increased wetted soil volume. Empirical regression equations accurately estimated the wetted lateral distance (Rl) and downward distance (Rd) with elapsed time in a variably wetted soil medium. Optimization of model parameters followed by the Inverse approach resulted in satisfactory agreement between observed and predicted cumulative infiltration and SWC. On the basis of model calibration, HYDRUS-2D model can accurately simulate two-dimensional soil water dynamics under irrigation of mulched furrows. There were significant differences in wetting patterns between unmulched and mulched furrow irrigation using HYDRUS-2D simulation. The Rd under the mulched furrows was 32.14%less than the unmulched furrows. Therefore, film-mulched furrows are recommended in a furrow irrigation system.

  14. Positive feedback stabilization of centrifugal compressor surge

    NARCIS (Netherlands)

    Willems, Frank; Heemels, W.P.M.H.; de Jager, Bram; Stoorvogel, Antonie Arij

    2002-01-01

    Stable operation of axial and centrifugal compressors is limited towards low mass flows due to the occurrence of surge. The stable operating region can be enlarged by active control. In this study, we use a control valve which is fully closed in the desired operating point and only opens to stabiliz

  15. Positive feedback stabilization of centrifugal compressor surge

    NARCIS (Netherlands)

    Willems, Frank; Heemels, W.P.M.H.; de Jager, Bram; Stoorvogel, Antonie Arij

    Stable operation of axial and centrifugal compressors is limited towards low mass flows due to the occurrence of surge. The stable operating region can be enlarged by active control. In this study, we use a control valve which is fully closed in the desired operating point and only opens to

  16. Computer-assisted mapping of pyroclastic surges.

    Science.gov (United States)

    Malin, M C; Sheridan, M F

    1982-08-13

    Volcanic hazard maps of surge boundaries and deposit thickness can be created by using a simplified eruption model based on an "energy line" concept of pyroclastic surge and flow emplacement. Computer image-processing techniques may be used to combine three-dimensional representations of the energy relations of pyroclasts moving under the influence of gravity (defined by an "energy cone") with digital topographic models of volcanoes to generate theoretical hazard maps. The deposit boundary and thickness calculated for the 18 May 1980 eruption of Mount St. Helens are qualitatively similar to those actually observed.

  17. Deep FIFO Surge Buffer

    Science.gov (United States)

    Temple, Gerald; Siegel, Marc; Amitai, Zwie

    1991-01-01

    First-in/first-out (FIFO) temporarily stores short surges of data generated by data-acquisition system at excessively high rate and releases data at lower rate suitable for processing by computer. Size and complexity reduced while capacity enhanced by use of newly developed, sophisticated integrated circuits and by "byte-folding" scheme doubling effective depth and data rate.

  18. Deep FIFO Surge Buffer

    Science.gov (United States)

    Temple, Gerald; Siegel, Marc; Amitai, Zwie

    1991-01-01

    First-in/first-out (FIFO) temporarily stores short surges of data generated by data-acquisition system at excessively high rate and releases data at lower rate suitable for processing by computer. Size and complexity reduced while capacity enhanced by use of newly developed, sophisticated integrated circuits and by "byte-folding" scheme doubling effective depth and data rate.

  19. Furrow Dike Water Conservation Practices in the Texas High Plains

    OpenAIRE

    Wistrand, Glen L.

    1984-01-01

    Furrow diking can prevent irrigation and rainfall runoff, conserve energy use, prevent soil loss, amd allow producers to reclaim land otherwise unusable, depending on soil, climate, and crops grown in a given area. Initial investment to use this technique may be recovered within the first season. This study analyzes the effects of diking on water and soil conservation, crop yields, costs, and energy use in farming, using examples of farms in the Texas High Plains area.

  20. Furrow Dike Water Conservation Practices in the Texas High Plains

    OpenAIRE

    Wistrand, Glen L.

    1984-01-01

    Furrow diking can prevent irrigation and rainfall runoff, conserve energy use, prevent soil loss, amd allow producers to reclaim land otherwise unusable, depending on soil, climate, and crops grown in a given area. Initial investment to use this technique may be recovered within the first season. This study analyzes the effects of diking on water and soil conservation, crop yields, costs, and energy use in farming, using examples of farms in the Texas High Plains area.

  1. The sejugal furrow in camel spiders and acariform mites

    Directory of Open Access Journals (Sweden)

    Dunlop, Jason A.

    2012-07-01

    Full Text Available Camel spiders (Arachnida: Solifugae are one of the arachnid groups characterised by a prosomal dorsal shield composed of three distinct elements: the pro-, meso- and metapeltidium. These are associated respectively with prosomal appendages one to four, five, and six. What is less well known, although noted in the historical literature, is that the coxae of the 4th and 5th prosomal segments (i.e. walking legs 2 and 3 of camel spiders are also separated ventrally by a distinct membranous region, which is absent between the coxae of the other legs. We suggest that this essentially ventral division of the prosoma specifically between coxae 2 and 3 is homologous with the so-called sejugal furrow (the sejugal interval sensu van der Hammen. This division constitutes a fundamental part of the body plan in acariform mites (Arachnida: Acariformes. If homologous, this sejugal furrow could represent a further potential synapomorphy for (Solifugae + Acariformes; a relationship with increasing morphological and molecular support. Alternatively, outgroup comparison with sea spiders (Pycnogonida and certain early Palaeozoic fossils could imply that the sejugal furrow defines an older tagma, derived from a more basal grade of organisation. In this scenario the (still divided prosoma of acariform mites and camel spiders would be plesiomorphic. This interpretation challenges the textbook arachnid character of a peltidium (or ‘carapace’ covering an undivided prosoma.

  2. Syndapin promotes pseudocleavage furrow formation by actin organization in the syncytial Drosophila embryo.

    Science.gov (United States)

    Sherlekar, Aparna; Rikhy, Richa

    2016-07-01

    Coordinated membrane and cytoskeletal remodeling activities are required for membrane extension in processes such as cytokinesis and syncytial nuclear division cycles in Drosophila Pseudocleavage furrow membranes in the syncytial Drosophila blastoderm embryo show rapid extension and retraction regulated by actin-remodeling proteins. The F-BAR domain protein Syndapin (Synd) is involved in membrane tubulation, endocytosis, and, uniquely, in F-actin stability. Here we report a role for Synd in actin-regulated pseudocleavage furrow formation. Synd localized to these furrows, and its loss resulted in short, disorganized furrows. Synd presence was important for the recruitment of the septin Peanut and distribution of Diaphanous and F-actin at furrows. Synd and Peanut were both absent in furrow-initiation mutants of RhoGEF2 and Diaphanous and in furrow-progression mutants of Anillin. Synd overexpression in rhogef2 mutants reversed its furrow-extension phenotypes, Peanut and Diaphanous recruitment, and F-actin organization. We conclude that Synd plays an important role in pseudocleavage furrow extension, and this role is also likely to be crucial in cleavage furrow formation during cell division.

  3. Demand surge following earthquakes

    Science.gov (United States)

    Olsen, Anna H.

    2012-01-01

    Demand surge is understood to be a socio-economic phenomenon where repair costs for the same damage are higher after large- versus small-scale natural disasters. It has reportedly increased monetary losses by 20 to 50%. In previous work, a model for the increased costs of reconstruction labor and materials was developed for hurricanes in the Southeast United States. The model showed that labor cost increases, rather than the material component, drove the total repair cost increases, and this finding could be extended to earthquakes. A study of past large-scale disasters suggested that there may be additional explanations for demand surge. Two such explanations specific to earthquakes are the exclusion of insurance coverage for earthquake damage and possible concurrent causation of damage from an earthquake followed by fire or tsunami. Additional research into these aspects might provide a better explanation for increased monetary losses after large- vs. small-scale earthquakes.

  4. Design of deepwater HP/HT pipe-in-pipe flowlines crossing mega-furrows in the Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Tianxi Andy; Chacko, Jacob; Zhou, Mengjuan Jane; Omonoji, Gabriel O. [TECHNIP USA, Houston, TX (United States); Eigbe, Uwa [INTECSEA, Houston, TX (United States)

    2009-07-01

    Two 12-mile long pipe-in-pipe (PIP) with HT/HP flow lines were recently designed for the Chinook offshore oil field in the Gulf of Mexico. The routes of the flow line of the Chinook crosses continuous mega-furrows at the water depth ranging from 8200 ft to 8800 ft. The design of the temperature and pressure of the flow lines were 250 deg F and 12,684 psi, respectively. The detailed finite element analysis was performed to predict flow line in-place behavior. The strain-based criterion of API RP 1111 was used where stresses were greater than allowable limits of the ASME B31.8 and found to be satisfactory. The fatigue analysis of the spans pipe subjected to Vortex Induced Vibration (VIV) showed the need for VIV mitigation measures. It was decided that the entire length of the flow lines crossing the mega-furrows should be stake. The analysis of the stake fatigue life of the flow lines resulted greater than the required 25 years service life. Further analysis was performed on the PIP system to optimize the centralizer spacing to sufficiently limit the buckling of inner pipe under operation conditions and prevent crushing of the insulation in the annulus. J-lay analysis of the installation determining the amount of the inner pipe pre-tensioning that was required to eliminate locked-in stresses in the inner and outer pipes. (author)

  5. Storm surge and river interaction in etuaries

    Science.gov (United States)

    Maskell, J.

    2012-04-01

    In coastal areas, particularly in regions developed on estuaries, extreme river flow can combine with storm surges to present a combined hazard. This combined risk is likely to be more prominent in estuaries where fluvial fresh water input comes from catchments in hilly regions where the dependence of extreme river discharge and sea level elevation can be most statistically significant (Svensson and Jones, 2004). The risk associated with these combined coastal hazards could increase due to climate change if there were an increase in the frequency of extreme weather events. The global (IPCC, 2007) and local (Woodworth et al., 2009) rise in mean sea-level will increase the magnitude of extreme sea levels and surges will act on a higher coastal sea level and therefore increase the risk to coastal property and infrastructure. This may be associated with an increase in precipitation during extreme storm events which will have a large impact on river flooding. Therefore, the need for accurate operational forecasting of storm events will increase with the focus shifting to changes in the extreme 'tail end' of the distribution of storm events. Ideally an operational model that integrates storm surge, wave and fluvial forecasting with inundation and simulates their combined influence would be most effective for planning with respect to flood plain development, evacuation and flood defence. Current operational storm surge models are typically based on two-dimensional depth-averaged shallow water equations (Flather, 2000). Inundation models often use an approximation of the original shallow water equations which neglect the inertial terms (Prestininzi et al., 2011). These 2D flood plain inundation models are often coupled with a 1D model of the main channel of a river or estuary which permits the exchange of mass but assumes a limited exchange of momentum (Bates et al., 2005). A finite volume model (FVCOM) is used to investigate the combined influence of storm surge and river

  6. Surge dynamics on Bering Glacier, Alaska, in 2008–2011

    Directory of Open Access Journals (Sweden)

    M. Braun

    2012-11-01

    Full Text Available A surge cycle of the Bering Glacier system, Alaska, is examined using observations of surface velocity obtained using synthetic aperture radar (SAR offset tracking, and elevation data obtained from the University of Alaska Fairbanks LiDAR altimetry program. After 13 yr of quiescence, the Bering Glacier system began to surge in May 2008 and had two stages of accelerated flow. During the first stage, flow accelerated progressively for at least 10 months and reached peak observed velocities of ~ 7 m d−1. The second stage likely began in 2010. By 2011 velocities exceeded 9 m d−1 or ~ 18 times quiescent velocities. Fast flow continued into July 2011. Surface morphology indicated slowing by fall 2011; however, it is not entirely clear if the surge is yet over. The quiescent phase was characterized by small-scale acceleration events that increased driving stresses up to 70%. When the surge initiated, synchronous acceleration occurred throughout much of the glacier length. Results suggest that downstream propagation of the surge is closely linked to the evolution of the driving stress during the surge, because driving stress appears to be tied to the amount of resistive stress provided by the bed. In contrast, upstream acceleration and upstream surge propagation is not dependent on driving stress evolution.

  7. Improving Sugarcane Water and Fertilizer Use Efficiency in Furrow Fertigation

    Directory of Open Access Journals (Sweden)

    F. Abbasi

    2016-02-01

    Full Text Available Introduction: Application of simultaneous nitrogen fertilizer and water as fertigation in surface irrigation systems is developing. In fertigation is possible to increase water and fertilizer use efficiency and it allows growers to apply nutrients in split and small amounts throughout the season in response to crop needs. In this study, sugarcane furrow fertigation experiments is carried out in Dehkhoda agro-industry company to improve fertilizer management, water and nitrogen use efficiency, and reduce urea fertilizer consumption. Materials and Methods: Large scale furrow experiments were conducted on a plant field. Field experiments were carried out as split plot with a complete randomized block design. Experimental treatments consisted of three fertilizer splits (2, 3, and 4 splits in main plots and three levels of urea fertilizer (60, 80 and 100% of required urea fertilizer in subplots and compared with the common method (control used in the agro-industry fields. Experiments were conducted on a 25 hectare field in 250 meter long and blocked end furrows. Irrigation water during the crop season was applied the same for different fertigation treatments and measured using the WSC flumes in each irrigation events. Irrigation interval varied from 8 to 15 days during the crop season. Qualitative and quantitative traits (e.i., stalk height, cane yield, purity, brix, white sugar yield, and water, fertilizer, and sugar use efficiency at harvest were measured and analyzed using the MSTATC software. Results and Discussions: A total of 21 irrigation events during the growing season were measured. Average water consumption in each irrigation event was 865 cubic meters per hectare. Total applied irrigation water during the growing season was 18,155 cubic meters per hectare. Results showed that fertilizer split factor significantly affected the qualitative and quantitative traits at a 5% level of significance. So that, all qualitative and quantitative

  8. Storm surge variational assimilation model

    Directory of Open Access Journals (Sweden)

    Shi-li HUANG

    2010-06-01

    Full Text Available To eliminate errors caused by uncertainty of parameters and further improve capability of storm surge forecasting, the variational data assimilation method is applied to the storm surge model based on unstructured grid with high spatial resolution. The method can effectively improve the forecasting accuracy of storm surge induced by typhoon through controlling wind drag force coefficient parameter. The model is first theoretically validated with synthetic data. Then, the real storm surge process induced by the TC 0515 typhoon is forecasted by the variational data assimilation model, and results show the feasibility of practical application.

  9. Estimation of furrow irrigation sediment loss using an artificial neural network

    Science.gov (United States)

    The area irrigated by furrow irrigation in the U.S. has been steadily decreasing but still represents about 20% of the total irrigated area in the U.S. Furrow irrigation sediment loss is a major water quality issue and a method for estimating sediment loss is needed to quantify the environmental imp...

  10. Waves of accelerated motion in a glacier approaching surge: the mini-surges of Variegated Glacier, Alaska, U.S.A.

    OpenAIRE

    Kamb, Barclay; Engelhardt, Hermann

    1987-01-01

    Periods of dramatically accelerated motion, in which the flow velocity increases suddenly from about 55 cm/d to a peak of 100-300 cm/d and then decreases gradually over the course of a day, occurred repeatedly during June and July 1978-81 in Variegated Glacier (Alaska), a surging-type glacier that surged in 1982-83. These "mini-surges" appear to be related mechanistically to the main surge. The flow-velocity peak propagates down-glacier as a wave at a speed of about 0.3 km/h, over a reach of ...

  11. Present dynamics and future prognosis of a slowly surging glacier

    Directory of Open Access Journals (Sweden)

    G. E. Flowers

    2010-10-01

    Full Text Available Glacier surges are a well-known example of an internal dynamic oscillation whose occurrence is not a direct response to the external climate forcing, but whose character (e.g. period, mechanism may depend on the glacier's environmental or climate setting. We examine the dynamics of a small (~5 km2 valley glacier in the Yukon Territory of Canada, where two previous surges have been photographically documented and an unusually slow surge is currently underway. To characterize the dynamics of the present surge, and to speculate on the future of this glacier, we employ a higher-order flowband model of ice dynamics with a Coulomb-friction sliding law in both diagnostic and prognostic simulations. Diagnostic (force balance calculations capture the measured ice-surface velocity profile only when high basal water pressures (55–90% of flotation are prescribed over the central region of the glacier, consistent with where evidence of the surge has been identified. This leads to sliding accounting for 50–100% of the total surface motion. Prognostic simulations, where the glacier geometry evolves in response to a prescribed surface mass balance, reveal a significant role played by a large bedrock bump beneath the current equilibrium line of the glacier. This bump provides resistance to ice flow sufficient to cause the formation of a bulge in the ice-surface profile. We suggest that the bedrock bump contributes to the propensity for surges in this glacier, such that conditions suppressing ice-bulge formation over the bump may also inhibit surges. In our calculations such a situation arises for sufficiently negative values of mass balance. Collectively, these results corroborate our interpretation of the current glacier flow regime as indicative of a "slow surge", and confirm a relationship between surge incidence or character and the net mass balance. Our results also highlight the importance of glacier bed topography in controlling ice

  12. Cell shape change and invagination of the cephalic furrow involves reorganization of F-actin.

    Science.gov (United States)

    Spencer, Allison K; Siddiqui, Bilal A; Thomas, Jeffrey H

    2015-06-15

    Invagination of epithelial sheets to form furrows is a fundamental morphogenetic movement and is found in a variety of developmental events including gastrulation and vertebrate neural tube formation. The cephalic furrow is a deep epithelial invagination that forms during Drosophila gastrulation. In the first phase of cephalic furrow formation, the initiator cells that will lead invagination undergo apicobasal shortening and apical constriction in the absence of epithelial invagination. In the second phase of cephalic furrow formation, the epithelium starts to invaginate, accompanied by both basal expansion and continued apicobasal shortening of the initiator cells. The cells adjacent to the initiator cells also adopt wedge shapes, but only after invagination is well underway. Myosin II does not appear to drive apical constriction in cephalic furrow formation. However, cortical F-actin is increased in the apices of the initiator cells and in invaginating cells during both phases of cephalic furrow formation. These findings suggest that a novel mechanism for epithelial invagination is involved in cephalic furrow formation.

  13. Dynamin regulates metaphase furrow formation and plasma membrane compartmentalization in the syncytial Drosophila embryo

    Directory of Open Access Journals (Sweden)

    Richa Rikhy

    2015-02-01

    Full Text Available The successive nuclear division cycles in the syncytial Drosophila embryo are accompanied by ingression and regression of plasma membrane furrows, which surround individual nuclei at the embryo periphery, playing a central role in embryo compartmentalization prior to cellularization. Here, we demonstrate that cell cycle changes in dynamin localization and activity at the plasma membrane (PM regulate metaphase furrow formation and PM organization in the syncytial embryo. Dynamin was localized on short PM furrows during interphase, mediating endocytosis of PM components. Dynamin redistributed off ingressed PM furrows in metaphase, correlating with stabilized PM components and the associated actin regulatory machinery on long furrows. Acute inhibition of dynamin in the temperature sensitive shibire mutant embryo resulted in morphogenetic consequences in the syncytial division cycle. These included inhibition of metaphase furrow ingression, randomization of proteins normally polarized to intercap PM and disruption of the diffusion barrier separating PM domains above nuclei. Based on these findings, we propose that cell cycle changes in dynamin orchestrate recruitment of actin regulatory machinery for PM furrow dynamics during the early mitotic cycles in the Drosophila embryo.

  14. Dynamin regulates metaphase furrow formation and plasma membrane compartmentalization in the syncytial Drosophila embryo

    Science.gov (United States)

    Rikhy, Richa; Mavrakis, Manos; Lippincott-Schwartz, Jennifer

    2015-01-01

    ABSTRACT The successive nuclear division cycles in the syncytial Drosophila embryo are accompanied by ingression and regression of plasma membrane furrows, which surround individual nuclei at the embryo periphery, playing a central role in embryo compartmentalization prior to cellularization. Here, we demonstrate that cell cycle changes in dynamin localization and activity at the plasma membrane (PM) regulate metaphase furrow formation and PM organization in the syncytial embryo. Dynamin was localized on short PM furrows during interphase, mediating endocytosis of PM components. Dynamin redistributed off ingressed PM furrows in metaphase, correlating with stabilized PM components and the associated actin regulatory machinery on long furrows. Acute inhibition of dynamin in the temperature sensitive shibire mutant embryo resulted in morphogenetic consequences in the syncytial division cycle. These included inhibition of metaphase furrow ingression, randomization of proteins normally polarized to intercap PM and disruption of the diffusion barrier separating PM domains above nuclei. Based on these findings, we propose that cell cycle changes in dynamin orchestrate recruitment of actin regulatory machinery for PM furrow dynamics during the early mitotic cycles in the Drosophila embryo. PMID:25661871

  15. Movement of bromide-ion and carbofuran in the humic sandy soil of a potato field with ridges and furrows : measurements in the field and computations with the PEARL model

    NARCIS (Netherlands)

    Leistra, M.; Boesten, J.J.T.I.

    2008-01-01

    In fields with ridges and furrows (like in potato growing), water flow and pesticide transport in soil may be more complicated than in level fields. In a field experiment, movement of bromide-ion (as a tracer) and of the insecticide carbofuran through a sandy soil with humic top layer to the groundw

  16. Present dynamics and future prognosis of a slowly surging glacier

    Directory of Open Access Journals (Sweden)

    G. E. Flowers

    2011-03-01

    Full Text Available Glacier surges are a well-known example of an internal dynamic oscillation whose occurrence is not a direct response to the external climate forcing, but whose character (i.e. period, amplitude, mechanism may depend on the glacier's environmental or climate setting. We examine the dynamics of a small (∼5 km2 valley glacier in Yukon, Canada, where two previous surges have been photographically documented and an unusually slow surge is currently underway. To characterize the dynamics of the present surge, and to speculate on the future of this glacier, we employ a higher-order flowband model of ice dynamics with a regularized Coulomb-friction sliding law in both diagnostic and prognostic simulations. Diagnostic (force balance calculations capture the measured ice-surface velocity profile only when non-zero basal water pressures are prescribed over the central region of the glacier, coincident with where evidence of the surge has been identified. This leads to sliding accounting for 50–100% of the total surface motion in this region. Prognostic simulations, where the glacier geometry evolves in response to a prescribed surface mass balance, reveal a significant role played by a bedrock ridge beneath the current equilibrium line of the glacier. Ice thickening occurs above the ridge in our simulations, until the net mass balance reaches sufficiently negative values. We suggest that the bedrock ridge may contribute to the propensity for surges in this glacier by promoting the development of the reservoir area during quiescence, and may permit surges to occur under more negative balance conditions than would otherwise be possible. Collectively, these results corroborate our interpretation of the current glacier flow regime as indicative of a slow surge that has been ongoing for some time, and support a relationship between surge incidence or character and the net mass balance. Our results also highlight the importance of glacier bed

  17. A rapid, membrane-dependent pathway directs furrow formation through RalA in the early Drosophila embryo.

    Science.gov (United States)

    Holly, Ryan M; Mavor, Lauren M; Zuo, Zhongyuan; Blankenship, J Todd

    2015-07-01

    Plasma membrane furrow formation is crucial in cell division and cytokinesis. Furrow formation in early syncytial Drosophila embryos is exceptionally rapid, with furrows forming in as little as 3.75 min. Here, we use 4D imaging to identify furrow formation, stabilization, and regression periods, and identify a rapid, membrane-dependent pathway that is essential for plasma membrane furrow formation in vivo. Myosin II function is thought to provide the ingression force for cytokinetic furrows, but the role of membrane trafficking pathways in guiding furrow formation is less clear. We demonstrate that a membrane trafficking pathway centered on Ras-like protein A (RalA) is required for fast furrow ingression in the early fly embryo. RalA function is absolutely required for furrow formation and initiation. In the absence of RalA and furrow function, chromosomal segregation is aberrant and polyploid nuclei are observed. RalA localizes to syncytial furrows, and mediates the movement of exocytic vesicles to the plasma membrane. Sec5, which is an exocyst complex subunit and localizes to ingressing furrows in wild-type embryos, becomes punctate and loses its cortical association in the absence of RalA function. Rab8 also fails to traffic to the plasma membrane and accumulates aberrantly in the cytoplasm in RalA disrupted embryos. RalA localization precedes F-actin recruitment to the furrow tip, suggesting that membrane trafficking might function upstream of cytoskeletal remodeling. These studies identify a pathway, which stretches from Rab8 to RalA and the exocyst complex, that mediates rapid furrow formation in early Drosophila embryos.

  18. Lethal thermal impact at periphery of pyroclastic surges: evidences at Pompeii

    National Research Council Canada - National Science Library

    Mastrolorenzo, Giuseppe; Petrone, Pierpaolo; Pappalardo, Lucia; Guarino, Fabio M

    2010-01-01

    The evaluation of mortality of pyroclastic surges and flows (PDCs) produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized...

  19. Lethal Thermal Impact at Periphery of Pyroclastic Surges: Evidences at Pompeii: e11127

    National Research Council Canada - National Science Library

    Giuseppe Mastrolorenzo; Pierpaolo Petrone; Lucia Pappalardo; Fabio M Guarino

    2010-01-01

      Background The evaluation of mortality of pyroclastic surges and flows (PDCs) produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized...

  20. Determination of the Stable Slope Configuration of Oval-Shaped Furrow Pits

    Institute of Scientific and Technical Information of China (English)

    ZHU Nai-long; ZHANG Shi-xiong

    2004-01-01

    The space effects of oval-shaped furrow pit slopes were analyzed by the elastic mechanics principle. The interaction of limit equilibrium slope angle, friction coefficient, cohesion and horizontal radius of oval-shaped furrow pits has been derived. The oval trumpet-like rock mass is homogeneous and elastic while only loadedby its dead weight. The interaction indicates that the deeper an oval-shaped furrow pit is excavated, the greater thelimit equilibrium slope angle. Both the theory base for reducing stripping waste rock in an oval- shaped furrow pitand the basic way to determine the configuration of a stable slope were developed from the mentioned interaction.The theory includes the preceding principles of stability analysis of slopes. Compared with the configuration deter-mined by traditional theory of slope stability, a great quantity of stripping waste rock can be reduced by that deter-mined in this paper under stable conditions.

  1. 7 CFR 58.218 - Surge tanks.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Surge tanks. 58.218 Section 58.218 Agriculture....218 Surge tanks. If surge tanks are used for hot milk, and temperatures of product including foam being held in the surge tank during processing, is not maintained at a minimum of 150 °F, then two...

  2. A surge of Perseibreen, Svalbard, examined using aerial photography and ASTER high resolution satellite imagery

    OpenAIRE

    Dowdeswell, Julian A.; Benham, Toby J.

    2003-01-01

    The identification of surge activity is important in assessing the duration of the active and quiescent phases of the surge cycle of Svalbard glaciers. Satellite and aerial photographic images are used to identify and describe the form and flow of Perseibreen, a valley glacier of 59 km2 on the east coast of Spitsbergen. Heavy surface crevassing and a steep ice front, indicative of surge activity, were first observed on Perseibreen in April 2002. Examination of high resolution (15 m) Advanced ...

  3. Surge dynamics on Bering Glacier, Alaska, in 2008–2011

    Directory of Open Access Journals (Sweden)

    M. Braun

    2012-03-01

    Full Text Available A 2008–2011 surge of Bering Glacier, Alaska is examined using observations of surface velocity and surface elevation change. Velocity measurements are obtained using synthetic aperture radar (SAR offset tracking and elevation data are obtained from the University of Alaska Fairbanks LiDAR altimetry program. Bering Glacier began to surge in May 2008 and had two phases of accelerated flow. The first phase accelerated progressively for at least 10 months and reached peak observed velocities of ~7 m d−1. Results suggest that during the quiescent phase, prior to the surge, periods of accelerated flow increased driving stresses up to 70% in a ~10 km-long section of the Lower Bering. When the first phase of the surge initiated, synchronous acceleration occurred throughout much of the glacier length, indicating widespread pressurization of the bed, but the largest accelerations initiated at the location where driving stress built up during quiescence. From there, rapid flow velocities propagated upstream and downstream across much of the glacier length and transpired as small, transient and unorganized propagation fronts. The second phase occurred in 2011 and was of comparable scale to the surge in 1993–1995, with velocities exceeding 9 m d−1 or ~18 times quiescent velocities.

  4. Soil physics and chemistry at a medieval ridge and furrow site in northeastern Germany

    Science.gov (United States)

    Hirsch, Florian; van der Maaten-Theunissen, Marieke; van der Maaten, Ernst; Schneider, Anna; Raab, Alexandra; Raab, Thomas

    2017-04-01

    The usage of non-reversible ploughs, mainly during the Middle Ages and until historic times, led to the formation of ridge and furrow systems. Due to improvements of agricultural techniques, these historic agricultural sites were often abandoned and are now marginal land. The parallel ridges and furrows are usually, if not destroyed by later conventional ploughing, preserved in present-day forests. In northeastern Germany ridge and furrow systems are normally several decameters long and up to ten meters wide. The height difference between ridge top and furrow bottom is up to 50 centimeters and is expected to cause significant contrasts of soil properties and vegetation. Furthermore, due to the abandonment of sites with ridges and furrows, soils on these sites are unique archives for studies on fertilization, soil carbon dynamics and soil development. Therefore, we are characterizing soil physics (bulk density, saturated soil hydraulic conductivity, texture) and soil chemistry (soil acidity, carbon and nitrogen content) on a type location of historic ridges and furrows about 100 km northwest of Berlin.

  5. Modeling and control of surge and rotating stall in compressors

    Energy Technology Data Exchange (ETDEWEB)

    Gravdahl, Jan Tommy

    1998-12-31

    Compressors are used in power generation and a variety of other applications. This thesis contains new results in the field of modeling and control of rotating stall and surge in compressors. A close coupled valve is included in the Moore-Greitzer compression system model and controllers for both surge and rotating stall is derived using backstepping. Disturbances, constant and time varying, are then taken into account, and non-linear controllers are derived. Stability results are given. Then, passivity is used to derive a simple surge control law for the closed coupled valve. This propositional control law is shown to stabilize the system even in the presence of time varying disturbances in mass flow and pressure. A novel model for an axial compression system with non-constant compressor speed is derived by extending the Moore-Greitzer model. Rotating stall and surge is studied in connection with acceleration of the compressor. Finally, a model for a centrifugal compression system with time varying compressor speed is derived. The variable speed compressor characteristic is derived based on energy losses in the compressor components. Active control of surge in connection with varying speed is studied. Semi-global exponential stability of the compression system with both surge and speed control is proven. 103 refs., 38 figs., 5 tabs.

  6. A High Density Storm Surge Monitoring Network: Evaluating the Ability of Wetland Vegetation to Reduce Storm Surge

    Science.gov (United States)

    Lawler, S.; Denton, M.; Ferreira, C.

    2013-12-01

    Recent tropical storm activity in the Chesapeake Bay and a potential increase in the predicted frequency and magnitude of weather systems have drawn increased attention to the need for improved tools for monitoring, modeling and predicting the magnitude of storm surge, coastal flooding and the respective damage to infrastructure and wetland ecosystems. Among other forms of flood protection, it is believed that coastal wetlands and vegetation can act as a natural barrier that slows hurricane flooding, helping to reduce the impact of storm surge. However, quantifying the relationship between the physical process of storm surge and its attenuation by wetland vegetation is an active area of research and the deployment of in-situ measuring devices is crucial to data collection efforts in this field. The United States Geological Survey (USGS) mobile storm-surge network has already successfully provided a framework for evaluating hurricane induced storm surge water levels on a regional scale through the use of in-situ devices installed in areas affected by storm surge during extreme events. Based on the success of the USGS efforts, in this study we adapted the monitoring network to cover relatively small areas of wetlands and coastal vegetation with an increased density of sensors. Groups of 6 to 10 water level sensors were installed in sites strategically selected in three locations on the Virginia coast of the lower Chesapeake Bay area to monitor different types of vegetation and the resulting hydrodynamic patterns (open coast and inland waters). Each group of sensors recorded time series data of water levels for both astronomical tide circulation and meteorological induced surge. Field campaigns were carried out to survey characteristics of vegetation contributing to flow resistance (i.e. height, diameter and stem density) and mapped using high precision GPS. A geodatabase containing data from field campaigns will support the development and calibration of

  7. The influence of climate during and after a glacial surge - A comparison of the last two surges of Fridtjovbreen, Svalbard

    Science.gov (United States)

    Lønne, Ida

    2014-02-01

    Glacial surges are periods of fast flow, often limited in space and time, and driven by internal conditions which are not fully explained. The quantity and variety of documented case-studies and settings demonstrate that the critical variables are difficult to isolate. In an alternative approach, two surges from the same basin were compared at Fridtjovhamna; one of the few known sites where this is possible. Fridtjovbreen is a polythermal glacier that has been through two recent surges: the last event (1991-2002) occurred during an unusually warm period in the high Arctic, whereas the previous surge culminated in 1861, around the Little Ice Age when many Svalbard-glaciers had their maximum Holocene extent. Based on a multi-disciplinary study, processes and landforms from the two episodes were compared with respect to ice-front movement rates, formation and decay of ice-cored moraines and glacial meltwater drainage patterns. The study demonstrates that moraines and meltwater traces from the oldest surge, locally well preserved, provide excellent opportunities for reconstructing the behavior of the ice-mass. The last surge, however, took place during a period with ablation rates never seen at this latitude, and 10 years after the maximum extent, the deglaciated areas onshore hardly show traces from the event.

  8. Methodology for surge pressure evaluation in a water injection system

    Energy Technology Data Exchange (ETDEWEB)

    Meliande, Patricia; Nascimento, Elson A. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Civil; Mascarenhas, Flavio C.B. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Lab. de Hidraulica Computacional; Dandoulakis, Joao P. [SHELL of Brazil, Rio de Janeiro, RJ (Brazil)

    2009-07-01

    Predicting transient effects, known as surge pressures, is of high importance for offshore industry. It involves detailed computer modeling that attempts to simulate the complex interaction between flow line and fluid in order to ensure efficient system integrity. Platform process operators normally raise concerns whether the water injection system is adequately designed or not to be protected against possible surge pressures during sudden valve closure. This report aims to evaluate the surge pressures in Bijupira and Salema water injection systems due to valve closure, through a computer model simulation. Comparisons among the results from empirical formulations are discussed and supplementary analysis for Salema system were performed in order to define the maximum volumetric flow rate for which the design pressure was able to withstand. Maximum surge pressure values of 287.76 bar and 318.58 bar, obtained in Salema and Bijupira respectively, using empirical formulations have surpassed the operating pressure design, while the computer model results have pointed the greatest surge pressure value of 282 bar in Salema system. (author)

  9. Brief Communication: Twelve-year cyclic surging episode at Donjek Glacier in Yukon, Canada

    Directory of Open Access Journals (Sweden)

    T. Abe

    2015-11-01

    Full Text Available Surge-type glaciers repeat their short active phase and much longer quiescent phase usually every several decades or longer, but detailed observations of the evolution cycles have been limited to a few glaciers. Here we report three surging episodes in 1989, 2001, and 2013 at Donjek Glacier in the Yukon, indicating remarkably regular and short repeat cycles of 12 years. The surging area is limited within the ~ 20 km section from the terminus, where the flow width significantly narrows than upstream, suggesting a strong control of the valley constriction on the surge dynamics.

  10. Brief Communication: Twelve-year cyclic surging episodes at Donjek Glacier in Yukon, Canada

    Science.gov (United States)

    Abe, Takahiro; Furuya, Masato; Sakakibara, Daiki

    2016-07-01

    Surge-type glaciers repeat their short active phase and their much longer quiescent phase usually every several decades or longer, but detailed observations of the evolution cycles have been limited to only a few glaciers. Here we report three surging episodes in 1989, 2001, and 2013 at Donjek Glacier in the Yukon, Canada, indicating remarkably regular and short repeat cycles of 12 years. The surging area is limited within the ˜ 20 km section from the terminus, originating in an area where the flow width significantly narrows downstream, suggesting a strong control of the valley constriction on the surge dynamics.

  11. Brief Communication: Twelve-year cyclic surging episode at Donjek Glacier in Yukon, Canada

    Science.gov (United States)

    Abe, T.; Furuya, M.; Sakakibara, D.

    2015-11-01

    Surge-type glaciers repeat their short active phase and much longer quiescent phase usually every several decades or longer, but detailed observations of the evolution cycles have been limited to a few glaciers. Here we report three surging episodes in 1989, 2001, and 2013 at Donjek Glacier in the Yukon, indicating remarkably regular and short repeat cycles of 12 years. The surging area is limited within the ~ 20 km section from the terminus, where the flow width significantly narrows than upstream, suggesting a strong control of the valley constriction on the surge dynamics.

  12. Medvezhiy Glacier surge in 2011

    Directory of Open Access Journals (Sweden)

    V. M. Kotlyakov

    2012-01-01

    Full Text Available The paper presents results of monitoring of the Medvezhiy Glacier state for the period from its surge of 2001 to the last pulsation of 2011. This monitoring is performed based on the photographing made from the Russian section of the International Space Station. Features, used for prediction of the glacier last movement, are pointed out. The earlier determined characteristic property of the Medvezhiy Glacier change from a phase of recovering to that of its fast movement has been substantiated. Mean period of the glacier pulsations, estimated from observations for the last century, is 13.5 years. A surge of the glacier left tributary is recognized.

  13. The 1982 eruptions of El Chichon volcano, Mexico (3): Physical properties of pyroclastic surges

    Science.gov (United States)

    Sigurdsson, H.; Carey, S. N.; Fisher, R. V.

    1987-04-01

    Two major pyroclastic surges generated during the 4 April 1982 eruption of El Chichon devastated an area of 153 km2 with a quasi-radial distribution around the volcano. The hot surge clouds carbonized wood throughout their extent and were too hot to allow accretionary lapilli formation by vapor condensation. Field evidence indicates voidage fraction of 0.99 in the surge cloud with extensive entrainment of air. Thermal calculations indicate that heat content of pyroclasts can heat entrained air and maintain high temperatures in the surge cloud. The dominant bed form of the surge deposits are sand waves shaped in dune forms with vertical form index of 10 20, characterized by stoss-side erosion and lee-side deposition of 1 10 cm reversely graded laminae. A systematic decrease in maximum lithic diameter with distance from source is accompanied by decrease in wavelength and amplitude. Modal analysis indicates fractionation of glass and pumice from the surge cloud relative to crystals, resulting in loss of at least 10% 25% of the cloud mass due to winnowing out of fines during surge emplacement. Greatest fractionation from the -1.0 0.0-∅ grain sizes reflects relatively lower pumice particle density in this range and segregation in the formative stages of the surge cloud. Extensive pumice rounding indicates abrasion during bed-load transport. Flow of pyroclastic debris in the turbulent surge cloud was by combination of bed-load and suspended-load transport. The surges are viewed as expanding pyroclastic gravity flows, which entrain and mix with air during transport. The balance between sedimentation at the base of the surge cloud and expansion due to entrainment of air contributed to low cloud density and internal turbulence, which persisted to the distal edge of the surge zone.

  14. Robust mechanisms of ventral furrow invagination require the combination of cellular shape changes

    Science.gov (United States)

    Conte, Vito; Muñoz, José J.; Baum, Buzz; Miodownik, Mark

    2009-03-01

    Ventral furrow formation in Drosophila is the first large-scale morphogenetic movement during the life of the embryo, and is driven by co-ordinated changes in the shape of individual epithelial cells within the cellular blastoderm. Although many of the genes involved have been identified, the details of the mechanical processes that convert local changes in gene expression into whole-scale changes in embryonic form remain to be fully understood. Biologists have identified two main cell deformation modes responsible for ventral furrow invagination: constriction of the apical ends of the cells (apical wedging) and deformation along their apical-basal axes (radial lengthening/shortening). In this work, we used a computer 2D finite element model of ventral furrow formation to investigate the ability of different combinations of three plausible elementary active cell shape changes to bring about epithelial invagination: ectodermal apical-basal shortening, mesodermal apical-basal lengthening/shortening and mesodermal apical constriction. We undertook a systems analysis of the biomechanical system, which revealed many different combinations of active forces (invagination mechanisms) were able to generate a ventral furrow. Two important general features were revealed. First that combinations of shape changes are the most robust to environmental and mutational perturbation, in particular those combining ectodermal pushing and mesodermal wedging. Second, that ectodermal pushing plays a big part in all of the robust mechanisms (mesodermal forces alone do not close the furrow), and this provides evidence that it may be an important element in the mechanics of invagination in Drosophila.

  15. 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

  16. Improvement of Performance Range of Centrifugal Compressors Gas by Surge Line Modification Using Active Controller Based on Fuzzy Logic

    Directory of Open Access Journals (Sweden)

    Pezhman Mohammadi

    2012-04-01

    Full Text Available In this work, surge of prevention is a critical problem in oil and gas industries, particularly when return gas flow or gas flow reduces in transportation of gas pipelines. This paper is illustrated new results about surge control of centrifugal compressors .surge phenomenon is flow unsteady state in compressors which causes damages seriously in compressor construction. Furthermore, it also demonstrates in comparison with anti surge control ،active surge control expands stability range.Active surge control which based on fuzzy logic،is the main idea that used in this investigation. Using fuzzy controller causes an improvement in compressor's condition and increase performance range of the compressor, in addition to prevention of any instability in compressor. The simulation results is also satisfactory.

  17. Deconvolution of the cellular force-generating subsystems that govern cytokinesis furrow ingression.

    Directory of Open Access Journals (Sweden)

    Christopher C Poirier

    Full Text Available Cytokinesis occurs through the coordinated action of several biochemically-mediated stresses acting on the cytoskeleton. Here, we develop a computational model of cellular mechanics, and using a large number of experimentally measured biophysical parameters, we simulate cell division under a number of different scenarios. We demonstrate that traction-mediated protrusive forces or contractile forces due to myosin II are sufficient to initiate furrow ingression. Furthermore, we show that passive forces due to the cell's cortical tension and surface curvature allow the furrow to complete ingression. We compare quantitatively the furrow thinning trajectories obtained from simulation with those observed experimentally in both wild-type and myosin II null Dictyostelium cells. Our simulations highlight the relative contributions of different biomechanical subsystems to cell shape progression during cell division.

  18. Geological Controls on Glacier Surging?: Statistics and Speculation

    Science.gov (United States)

    Flowers, G. E.; Crompton, J. W.

    2015-12-01

    Glacier surging represents an end-member behavior in the spectrum of ice dynamics, involving marked acceleration and high flow speeds due to abrupt changes in basal mechanics. Though much effort has been devoted to understanding the role of basal hydrology and thermal regime in fast glacier flow, fewer studies have addressed the potential role of the geologic substrate. One interesting observation is that surge-type glaciers appear almost universally associated with unconsolidated (till) beds, and several large-scale statistical studies have revealed correlations between glacier surging and bedrock properties. We revisit this relationship using field measurements. We selected 20 individual glaciers for sampling in a 40x40 km region of the St. Elias Mountains of Yukon, Canada. Eleven of these glaciers are known to surge and nine are not. The 20 study glaciers are underlain by lithologies that we have broadly classified into two types: metasedimentary only and mixed metasedimentary-granodiorite. We characterized geological and geotechnical properties of the bedrock in each basin, and analyzed the hydrochemistry and mineralogy and grain size distribution (GSD) of the suspended sediments in the proglacial streams. Here we focus on some intriguing results of the GSD analysis. Using statistical techniques, including significance testing and principal component analysis, we find that: (1) lithology determines GSD for non-surge-type glaciers, with metasedimentary basins associated with finer mean grain sizes and mixed-lithology basins with coarser mean grain sizes, but (2) the GSDs associated with surge-type glaciers are intermediate between the distributions described above, and are statistically indistinguishable between metasedimentary and mixed lithology basins. The latter suggests either that surge-type glaciers in our study area occur preferentially in basins where various processes conspire to produce a characteristic GSD, or that the surge cycle itself exerts an

  19. Comments on metal oxide surge arresters surges energy absorption capacity

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, M.L.B. [Escola Federal de Engenharia de Itajuba, Minas Gerais (Brazil); Zanetta, L.C. Jr. [E. Politecnica Univ. de Sao Paulo, Sao Paulo (Brazil)

    1996-12-31

    This paper presents an approach to determine the energy absorption capacity of metal oxide surge arrester resistors. The proposed approach deals with the discharge current peak versus discharge current time relation. A testing method and a statistical evaluation are proposed. After determining the discharge current withstanding limit of the tested metal oxide resistors, the prospective energy absorption capacity limit is computed. Finally, comments on the obtained results are presented.

  20. Swift snowmelt and floods (lahars) caused by great pyroclastic surge at Mount St Helens volcano, Washington, 18 May 1980

    Science.gov (United States)

    Waitt, R.B.

    1989-01-01

    The initial explosions at Mount St. Helens, Washington, on the moring of 18 May 1980 developed into a huge pyroclastic surge that generated catastrophic floods off the east and west flanks of the volcano. Near-source surge deposits on the east and west were lithic, sorted, lacking in accretionary lapilli and vesiculated ash, not plastered against upright obstacles, and hot enough to char wood - all attributes of dry pyroclastic surge. Material deposited at the surge base on steep slopes near the volcano transformed into high-concentration lithic pyroclastic flows whose deposits contain charred wood and other features indicating that these flows were hot and dry. Stratigraphy shows that even the tail of the surge had passed the east and west volcano flanks before the geomorphically distinct floods (lahars) arrived. This field evidence undermines hypotheses that the turbulent surge was itself wet and that its heavy components segregated out to transform directly into lahars. Nor is there evidence that meters-thick snow-slab avalanches intimately mixed with the surge to form the floods. The floods must have instead originated by swift snowmelt at the base of a hot and relatively dry turbulent surge. Impacting hot pyroclasts probably transferred downslope momentum to the snow surface and churned snow grains into the surge base. Melting snow and accumulating hot surge debris may have moved initially as thousands of small thin slushflows. As these flows removed the surface snow and pyroclasts, newly uncovered snow was partly melted by the turbulent surge base; this and accumulating hot surge debris in turn began flowing, a self-sustaining process feeding the initial flows. The flows thus grew swiftly over tens of seconds and united downslope into great slushy ejecta-laden sheetfloods. Gravity accelerated the floods to more than 100 km/h as they swept down and off the volcano flanks while the snow component melted to form great debris-rich floods (lahars) channeled into

  1. Winter speed-up of two surging glaciers in West Kunlun Shan, Northwestern Tibet

    Science.gov (United States)

    Yasuda, T.; Furuya, M.

    2015-12-01

    We detected winter speed-up of two surging glaciers in the West Kunlun Shan (WKS), based on satellite Synthetic Aperture Radar (SAR) images since 2007. Surging glacier is a surge-type glacier in the active phase, flowing rapidly and transporting ice masses into the down-glaciers. The WKS is located in northwestern Tibetan Plateau (TP) and is one of the driest and the coldest place around TP. Accumulation and ablation mostly occur in summer season from May to August [Zhang et al., 1989; Maussion et al., 2014]. Zhang et al. (1989) estimated the annual average precipitation and temperature near the equilibrium line altitude (5930 m) is 300 mm and -13.9 deg. C, respectively. Under this sub-polar environment, polythermal glaciers exist in the WKS [Aniya, 2008]. We detected development of two surging flow with unprecedented temporal resolution up to 11 days. The two surging initiated around 2000 and continued by 2015. Surging flow accelerated at least 200 m/year. Moreover, it seasonally fluctuated their flow speed up to 200% in early winter against those in spring to early summer. The observed seasonal modulation in the surface velocities strongly suggests the presence of surface meltwater and subsequent rerouting through englacial and subglacial drainage system under a years-long surging glacier in the sub-polar environment.

  2. INCREASED FLEXIBILITY OF TURBO-COMPRESSORS IN NATURAL GAS TRANSMISSION THROUGH DIRECT SURGE CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    Robert J. Mckee; Danny M. Deffenbaugh

    2003-12-01

    This annual progress report describes the second year's technical progress in a three-year program. This report summarizes what is known about internal flows as surge precursors in centrifugal compressors and focuses on accessing factors that affect pre-surge detection. An attempt is made in this analysis to identify and quantify factors concerning compressor design and operations that affect the detection of pre-surge conditions. This progress report presents results from recent laboratory tests conducted during the course of this second year. This project is co-funded by the Gas Machinery Research Council (GMRC) and by Siemens Energy and Automation (Siemens). The most recently available measured pre-surge internal flow data is parameterized to help identify factors that affect the indications that a compressor is approaching surge. Theoretical arguments are applied to access the factors that influence surge precursors and surge initiation in different centrifugal compressors. This work is considered a step in accessing the factors that affect the success or limitations of pre-surge detection in natural gas pipeline compressors.

  3. Medvezhiy Glacier surge in 2011

    OpenAIRE

    V. M. Kotlyakov; L. V. Desinov

    2012-01-01

    The paper presents results of monitoring of the Medvezhiy Glacier state for the period from its surge of 2001 to the last pulsation of 2011. This monitoring is performed based on the photographing made from the Russian section of the International Space Station. Features, used for prediction of the glacier last movement, are pointed out. The earlier determined characteristic property of the Medvezhiy Glacier change from a phase of recovering to that of its fast movement has been substantiated...

  4. Lake Borgne Surge Barrier Study

    Science.gov (United States)

    2010-09-01

    Savant , and Darla C. McVan September 2010 Approved for public release; distribution is unlimited. ERDC/CHL TR-10-10 September 2010 Lake...Borgne Surge Barrier Study S. Keith Martin, Gaurav Savant , and Darla C. McVan Coastal and Hydraulics Laboratory U.S. Army Engineer Research and...conducted by Keith Martin, Dr. Gaurav Savant , and Darla C. McVan. This work was conducted at the Coastal and Hydraulics Laboratory (CHL) of the

  5. Dynamic stall on a pitching and surging airfoil

    Science.gov (United States)

    Dunne, Reeve; McKeon, Beverley J.

    2015-08-01

    Vertical axis wind turbine blades undergo dynamic stall due to the large angle of attack variation they experience during a turbine rotation. The flow over a single blade was modeled using a sinusoidally pitching and surging airfoil in a non-rotating frame with a constant freestream flow at a mean chord Reynolds number of . Two-dimensional, time-resolved velocity fields were acquired using particle image velocimetry. Vorticity contours were used to visualize shear layer and vortex activity. A low-order model of dynamic stall was developed using dynamic mode decomposition, from which primary and secondary dynamic separation modes were identified. The interaction between these two modes was able to capture the physics of dynamic stall and as such can be extended to other turbine configurations and problems in unsteady aerodynamics. Results from the linear pitch/surge frame are extrapolated to the rotating VAWT frame to investigate the behavior of identified flow structures.

  6. The worst moment of superposed surge wave in upstream series double surge tanks of hydropower station

    Science.gov (United States)

    Teng, Y.; Yang, J. D.; Guo, W. C.; Chen, J. P.

    2016-11-01

    It is a consensus to consider the superposed working conditions when calculating the surge wave in surge tank of hydropower station with long diversion tunnel. For the hydropower station with single surge tank, the method of determining the worst superposed moment is mature. However, for the hydropower station with upstream series double surge tanks, research in this field is still blank. Based on an engineering project, this paper investigated the worst moments and the control superposed working conditions about the maximum surge level and the minimum surge level of upstream series double surge tanks using numerical simulation. In addition, the incidence relations between the worst moment of superposed surge wave and the different areal array and distance between the two surge tanks are also carried out. The results showed that: With the decrease of the distance between auxiliary surge tank and upstream reservoir, the maximum values of the highest surge levels in the two surge tanks always reach close to but a little earlier than the bigger one time when the inflowing discharges of the two surge tanks reach the maximum. It is similar to the minimum values of lowest surge levels in the two surge tanks which also reach close to but a little later than the bigger one time when the outflowing discharges of the two surges reach the maximum. Moreover, the closer the area of auxiliary surge tank to the area of main surge tank is, the closer the worst moment to the bigger one time when inflow or outflow of the two surges reach the maximum will become.

  7. Rice grain yield as affected by subsoiling, compaction on sowing furrow and seed treatment

    Directory of Open Access Journals (Sweden)

    Veneraldo Pinheiro

    2016-05-01

    Full Text Available ABSTRACT This study aimed to determine the effects of subsoiling, compaction on sowing furrow and seed treatments with insecticides on the grain yield of upland rice cultivated under no-tillage. Two experiments were carried out, one in an area with and the other in an area without subsoiling, in which five seed treatments combined with five compaction pressures on the sowing furrow were compared in a randomized block design, in a factorial scheme, with three replicates. The seed treatments were: T0 - without treatment, T1 - imidacloprid + thiodicarb, T2 - thiamethoxam, T3 - carbofuran, and T4 - fipronil + pyraclostrobin + thiophanate methyl. The compaction pressures were: 25, 42, 126, 268 and 366 kPa. Subsoiling positively affected rice yield in the presence of higher compaction pressures on the sowing furrow. Seed treatment was effective at increasing rice grain yield only at the lowest compaction pressures. Rice yield showed quadratic response to compaction on the sowing furrow, with maximum values obtained at pressures ranging from 238.5 to 280.3 kPa.

  8. Water quality of surface runoff and lint yield in cotton under furrow irrigation in Northeast Arkansas

    Science.gov (United States)

    Use of furrow irrigation in row crop production is a common practice through much of the Midsouth US. Problems with these systems arise when nutrients are transported off-site through surface runoff. A field study with cotton (Gossypium hirsutum, L.) was conducted to understand the impact of tillage...

  9. SURDEV: surface irrigation software; design, operation, and evaluation of basin, border, and furrow irrigation

    NARCIS (Netherlands)

    Jurriëns, M.; Zerihun, D.; Boonstra, J.; Feyen, J.

    2001-01-01

    SURDEV is a computer package for the design, operation, and evaluation of surface irrigation. SURDEV combines three sub-programs: BASDEV (for basin irrigation), FURDEV (for furrow irrigation), and BORDEV for (border irrigation). This combination enables the user to simulate many of the problems invo

  10. SURDEV: surface irrigation software; design, operation, and evaluation of basin, border, and furrow irrigation

    NARCIS (Netherlands)

    Jurriëns, M.; Zerihun, D.; Boonstra, J.; Feyen, J.

    2001-01-01

    SURDEV is a computer package for the design, operation, and evaluation of surface irrigation. SURDEV combines three sub-programs: BASDEV (for basin irrigation), FURDEV (for furrow irrigation), and BORDEV for (border irrigation). This combination enables the user to simulate many of the problems

  11. Increasing energy efficiency by geometric modification of hoe-type furrow opener

    Directory of Open Access Journals (Sweden)

    R Rahimzadeh

    2016-09-01

    Full Text Available Introduction Direct planting becomes more common in the recent years, because it conserves soil and water as well as it saves energy and time. However, this technology needs special implements such as seed planter. Given that direct planting is practiced in undisturbed lands, so it was needed to design a special furrow opener. In order to obtain a suitable furrow opener this experiment was conducted in rain-fed Agricultural Research Institute in Maragheh. Materials and Methods Most of seed planters that are used for cultivation in rain fed conditions are equipped by hoe-type furrow opener. Hoe-type furrow openers have good penetration in hard and dry soils. However, they do not have the ability for direct planting. Hoe-type furrow opener was chosen as a model. Then by changing the geometric form of the depth to width ratio (d/w, the two openers were designed. In the first design, which was called O1 two wings and a narrow blade acting as a coulter were added in front of the hoe-type furrow opener. In the second design, which was called O2, in addition to the O1 modification, furrow opener width was decreased and a disk blade was added for seed sowing (Fig. 1. The performance of O1 and O2 openers were compared with the conventional hoe-type furrow opener (check in soil bin and in field conditions. At three different forward speeds (1, 1.5 and 2 m.s-1 with 3 replications, the effects of the openers designs of vertical and horizontal soil forces were evaluated in soil-bin conditions. In order to evaluate the performance of the furrow opener in field conditions, an experiment was conducted using a split plot design based on RCBD at 4 replications. Furrow openers formed the main plots and forward speeds formed the sub plots. Each plot size was 22 meters long in two rows for each treatment. After germination of wheat crop, the numbers of seedlings in two rows were counted (along a one meter. After crop maturity, all plots were harvested by hand and

  12. Increasing energy efficiency by geometric modification of hoe-type furrow opener

    Directory of Open Access Journals (Sweden)

    R Rahimzadeh

    2016-09-01

    Full Text Available Introduction Direct planting becomes more common in the recent years, because it conserves soil and water as well as it saves energy and time. However, this technology needs special implements such as seed planter. Given that direct planting is practiced in undisturbed lands, so it was needed to design a special furrow opener. In order to obtain a suitable furrow opener this experiment was conducted in rain-fed Agricultural Research Institute in Maragheh. Materials and Methods Most of seed planters that are used for cultivation in rain fed conditions are equipped by hoe-type furrow opener. Hoe-type furrow openers have good penetration in hard and dry soils. However, they do not have the ability for direct planting. Hoe-type furrow opener was chosen as a model. Then by changing the geometric form of the depth to width ratio (d/w, the two openers were designed. In the first design, which was called O1 two wings and a narrow blade acting as a coulter were added in front of the hoe-type furrow opener. In the second design, which was called O2, in addition to the O1 modification, furrow opener width was decreased and a disk blade was added for seed sowing (Fig. 1. The performance of O1 and O2 openers were compared with the conventional hoe-type furrow opener (check in soil bin and in field conditions. At three different forward speeds (1, 1.5 and 2 m.s-1 with 3 replications, the effects of the openers designs of vertical and horizontal soil forces were evaluated in soil-bin conditions. In order to evaluate the performance of the furrow opener in field conditions, an experiment was conducted using a split plot design based on RCBD at 4 replications. Furrow openers formed the main plots and forward speeds formed the sub plots. Each plot size was 22 meters long in two rows for each treatment. After germination of wheat crop, the numbers of seedlings in two rows were counted (along a one meter. After crop maturity, all plots were harvested by hand and

  13. Comparison of lettuce diseases and yield under subsurface drip and furrow irrigation.

    Science.gov (United States)

    Subbarao, K V; Hubbard, J C; Schulbach, K F

    1997-08-01

    ABSTRACT Subsurface drip and furrow irrigation were compared on lettuce (Lactuca sativa) cvs. Salinas and Misty Day for yield and incidence and severity of three important diseases of lettuce in the Salinas Valley, CA. Experiments were conducted between 1993 and 1995 during the spring and fall seasons. The diseases examined included lettuce drop (Sclerotinia minor), downy mildew (Bremia lactucae), and corky root (Rhizomonas suberifaciens). Replicated plots of subsurface drip and furrow irrigation were arranged in a randomized complete-block design. All plants were inoculated with S. minor at the initiation of the experiment during the 1993 spring season. Plots were not inoculated for downy mildew and corky root during any season nor were the plots reinoculated with S. minor. During each season, all plots were sprinkler irrigated until thinning, and subsequently, the irrigation treatments were begun. The furrow plots were irrigated once per week, and the drip plots received water twice per week. The distribution of soil moisture at two soil depths (0 to 5 and 6 to 15 cm) at 5, 10, and 15 cm distance on either side of the bed center in two diagonal directions was significantly lower in drip-irrigated compared with furrow-irrigated plots. Plots were evaluated for lettuce drop incidence and downy mildew incidence and severity at weekly intervals until harvest. Corky root severity and yield components were determined at maturity. Lettuce drop incidence and corky root severity were significantly lower and yields were higher in plots under subsurface drip irrigation compared with furrow irrigation, regardless of the cultivar, except during the 1994 fall season. Incidence and severity of downy mildew were not significantly different between the two irrigation methods throughout the study. The differential microclimates created by the two irrigation treatments did not affect downy mildew infection, presumably because the mesoclimate is usually favorable in the Salinas

  14. Water quality of surface runoff and lint yield in cotton under furrow irrigation in Northeast Arkansas.

    Science.gov (United States)

    Adviento-Borbe, M Arlene A; Barnes, Brittany D; Iseyemi, Oluwayinka; Mann, Amanda M; Reba, Michele L; Robertson, William J; Massey, Joseph H; Teague, Tina G

    2017-09-11

    Use of furrow irrigation in row crop production is a common practice through much of the Midsouth US and yet, nutrients can be transported off-site through surface runoff. A field study with cotton (Gossypium hirsutum, L.) was conducted to understand the impact of furrow tillage practices and nitrogen (N) fertilizer placement on characteristics of runoff water quality during the growing season. The experiment was designed as a randomized complete block design with conventional (CT) and conservation furrow tillage (FT) in combination with either urea (URN) broadcast or 32% urea ammonium nitrate (UAN) injected, each applied at 101kgNha(-1). Concentrations of ammonium (NH4-N), nitrate (NO3-N), nitrite (NO2-N), and dissolved phosphorus (P) in irrigation runoff water and lint yields were measured in all treatments. The intensity and chemical form of nutrient losses were primarily controlled by water runoff volume and agronomic practice. Across tillage and fertilizer N treatments, median N concentrations in the runoff were irrigation water and less likely to impair pollution in waterways. Lint yields averaged 1111kgha(-1) and were higher (P-value=0.03) in FT compared to CT treatments. Runoff volumes across irrigation events were greater (P-value=0.02) in CT than FT treatments, which increased NO3-N mass loads in CT treatments (394gNO3-Nha(-1)season(-1)). Nitrate-N concentrations in CT treatments were still low and pose little threat to N contaminations in waterways. The findings support the adoption of conservation practices for furrow tillage and N fertilizer placement that can reduce nutrient runoff losses in furrow irrigation systems. Copyright © 2017. Published by Elsevier B.V.

  15. Forces and straw cutting performance of double disc furrow opener in no-till paddy soil.

    Science.gov (United States)

    Ahmad, Fiaz; Weimin, Ding; Qishuo, Ding; Hussain, Mubshar; Jabran, Khawar

    2015-01-01

    Conservation tillage is an energy efficient and low cost tillage system to improve soil environment compared with conventional tillage systems. However, the rice residue management becomes an "impossible to achieve" task due to high soil moisture content at harvest time and the thickness of rice straw. Disc type furrow openers are used for both seed drilling as well as straw cutting during no tillage sowing. A study was conducted to evaluate the draft requirement and straw cutting performances of different sized furrow openers in no-till paddy soil conditions. Double disc furrow opener was tested on an in-field traction bench for three working depths, i.e. 30, 60 and 90 mm, and three forwarding speeds, i.e. 0.1, 0.2 and 0.3 m/s. The draft and vertical forces on the disc were recorded with load cells. These sensors were connected to a data acquisition system developed with hardware and software. The results revealed that the size of the furrow opener, operating depth and the forwarding speed had significant effects (Pcutting performance. Mean values of the draft were 648.9, 737.2 and 784.6 N for the opener with diameters of 330, 450 and 600 mm respectively, and the vertical forces for similar openers were 904.7, 1553.9 and 1620.4 N, respectively. Furthermore, the mean straw cutting efficiencies for the double disc opener with diameters of 330, 450 and 600 mm were 39.36, 78.47 and 65.46%, respectively. The opener with 450 mm diameter provided higher straw cutting efficiency as compared to 600 mm diameter disc, while lowest straw cutting efficiency was observed with 330 mm diameter disc. The 450 mm diameter opener provided the highest straw cutting efficiency (88.6%) at 90 mm working depth and expressed optimum performance compared with other furrow openers.

  16. Linkage of Rainfall-Runoff and Hurricane Storm Surge in Galveston Bay

    Science.gov (United States)

    Deitz, R.; Christian, J.; Wright, G.; Fang, N.; Bedient, P.

    2012-12-01

    In conjunction with the SSPEED Center, large rainfall events in the upper Gulf of Mexico are being studied in an effort to help design a surge gate to protect the Houston Ship Channel during hurricane events. The ship channel is the world's second largest petrochemical complex and the Coast Guard estimates that a one-month closure would have a $60 billion dollar impact on the national economy. In this effort, statistical design storms, such as the 24-hour PMP, as well as historical storms, like Hurricane Ike, Hurricane Katrina, and Hurricane Rita, are being simulated in a hydrologic/hydraulic model using radar and rain gauge data. VfloTM, a distributed hydrologic model, is being used to quantify the effect that storm size, intensity, and location has on timing and peak flows in the in the upper drainage area. These hydrographs were input to a hydraulic model with various storm surges from Galveston Bay. Results indicate that there is a double peak phenomenon with flows from the west draining days earlier than flows from the north. With storm surge typically lasting 36-48 hours, this indicates the flows from the west are interacting with the storm surge, whereas flows from the north would arrive once the storm surge is receding. Gate operations were optimized in the model to account for the relative timing of upland runoff and hurricane surge, and to quantify the capability of the gate structure to protect the Ship Channel industry.

  17. Identifying surging glaciers in the Central Karakoram for improved climate change impact assessment

    Science.gov (United States)

    Paul, Frank; Bolch, Tobias; Mölg, Nico; Rastner, Philipp

    2015-04-01

    Several recent studies have investigated glacier changes in the Karakoram mountain range, a region where glaciers behave differently (mass gain and advancing tongues) compared to most other regions in the world. Attribution of this behaviour to climate change is challenging, as many glaciers in the Karakoram are of surge type and have actively surged in the recent past. The measured changes in length, area, volume or velocity in this region are thus depending on the time-period analysed and include non-climatic components. Hence, a proper analysis of climate change impacts on glaciers in this region requires a separation of the surging from the non-surging glaciers. This is challenging as the former often lack the typical surface characteristics such as looped moraines (e.g. when they are steep and small) and/or they merge (during a surge) with a larger non-surging glacier and create looped moraines on its surface. By analysing time series of satellite images that are available since 1961, the heterogeneous behaviour of glaciers in the Karakoram can be revealed. In this study, we have analysed changes in glacier terminus positions in the Karakoram over different time periods from 1961 to 2014 for several hundred glaciers using Corona KH-4 and KH-4B, Hexagon KH-9, Terra ASTER, and Landsat MSS, TM, ETM+ and OLI satellite data. For the last 15 years, high-speed animations of image time-series reveal details of glacier flow and surge dynamics that are otherwise difficult to detect. For example, several of the larger glaciers with surging tributaries (e.g. Panmah, Sarpo Laggo, Skamri, K2 glacier) are stationary and downwasting despite the mass contributions from the surging glaciers. The analysis of the entire time series reveals a complex pattern of changes through time with retreating, advancing, surging and stationary glaciers that are partly regionally clustered. While most of the non-surging glaciers show only small changes in terminus position (±100 m or less

  18. Quantification of Sediment Transport During Glacier Surges and its Impact on Landform Architecture

    Science.gov (United States)

    Kjaer, K. H.; Schomacker, A.; Korsgaard, N. J.; Benediktsson, I. O.

    2008-12-01

    Multi-temporal DEMs (Digital Elevation Models) of glaciers and ice streams have successfully been used for extraction of changes in ice volume over time. In this study, we analysed DEMs of the Brúarjökull glacier forefield (Iceland) for 1945, prior to the last surge in 1964, and for 2003 in order to assess the effect of the surge on the sediment architecture in the forefield. The pre- and post-surge DEMs allow direct quantification of the sediment volumes that were re-distributed in the forefield by the surging ice mass in 1964. The surge-type glacier Brúarjökull has experienced six surges during the last four centuries; these are the largest surges known to have occurred in Iceland. During the most recent surge in 1963-64, the glacier advanced 8 km over a period of c. 3 months with a maximum ice flow velocity of 5 m/hr, and 700 km3 of ice were moved downglacier. The continued recession of Brúarjökull since the 1963-64 surge reveals a young landscape consisting of widely spaced and elongated bedrock hills interspaced with shallow sedimentary basins. The majority of the forefield is covered with a basal till sheet or glaciofluvial outwash fans. Mapping of the sediment thickness in the glacier forefield shows higher accumulation along ice marginal positions related to wedge formation during extremely rapid ice flow. Fast flow was sustained by overpressurized water causing sediment-bedrock decoupling beneath a thick sediment sequence that was coupled to the glacier. Elevation differences between the terrain surface in 1945 and 2003 confirm this scenario as huge quantities of sediment was eroded, deformed and transported during the last surge event. On the scale of individual landforms, it appears for a drumlin surface that is has been lowered 20 m from 1945-2003. Dead-ice melting can explain roughly 8 m of this lowering. Thus, the drumlin must have experienced 12 m of subglacial erosion during the 1964 surge. The imprint of at least four landform generations is

  19. Observing storm surges from satellite altimetry

    Science.gov (United States)

    Han, Guoqi

    2016-07-01

    Storm surges can cause catastrophic damage to properties and loss of life in coastal communities. Thus it is important to enhance our capabilities of observing and forecasting storm surges for mitigating damage and loss. In this presentation we show examples of observing storm surges around the world using nadir satellite altimetry, during Hurricane Sandy, Igor, and Isaac, as well as other cyclone events. The satellite observations are evaluated against tide-gauge observations and discussed for dynamic mechanisms. We also show the potential of a new wide-swath altimetry mission, the Surface Water and Ocean Topography (SWOT), for observing storm surges.

  20. Reconnaissance level study Mississippi storm surge barrier

    NARCIS (Netherlands)

    Van Ledden, M.; Lansen, A.J.; De Ridder, H.A.J.; Edge, B.

    2012-01-01

    This paper reports a reconnaissance level study of a storm surge barrier in the Mississippi River. Historical hurricanes have shown storm surge of several meters along the Mississippi River levees up to and upstream of New Orleans. Future changes due to sea level rise and subsidence will further

  1. Influence of Surge on Extreme Roll Amplitudes

    DEFF Research Database (Denmark)

    Vidic-Perunovic, Jelena; Rognebakke, Olav; Pedersen, Preben Terndrup

    2008-01-01

    Interference of the wave-induced ship surge motion with roll dynamics has been studied. The surge motion has been included in a previously derived hydrodynamic roll prediction model in order to account for the ship speed variation due to the longitudinal incident wave pressure force. Depending on...

  2. Reconnaissance level study Mississippi storm surge barrier

    NARCIS (Netherlands)

    Van Ledden, M.; Lansen, A.J.; De Ridder, H.A.J.; Edge, B.

    2012-01-01

    This paper reports a reconnaissance level study of a storm surge barrier in the Mississippi River. Historical hurricanes have shown storm surge of several meters along the Mississippi River levees up to and upstream of New Orleans. Future changes due to sea level rise and subsidence will further inc

  3. Compression station anti-surge system considerations

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, Rainer; White, Robert C. [Solar Turbines Incorporated, Houston, TX (United States)

    2005-07-01

    Centrifugal compressor surge and its prevention have drawn significant attention in the literature. An important aspect of surge avoidance lies in the design of the compressor station and, in particular, the piping upstream and downstream of the compressor. Most anti-surge systems are perfectly capable of avoiding surge during normal operating conditions. However, unplanned emergency shutdowns present a significant challenge, and surge avoidance in these cases depends to a large degree on the station layout. Furthermore, the concepts used in the anti surge system (valves, piping, coolers) also impact the start-up of the station, or of individual units of the station. In this paper a simplified surge control system model is presented and used to develop simpler rules that help with proper sizing of upstream and downstream piping systems, as well as the necessary control element. Since the design of the surge control and recycle system also affects the start-up of units and stations, start-up considerations for stations with and without cooled recycle loops are discussed. (author)

  4. Luminescence dating of storm-surge sediment

    NARCIS (Netherlands)

    Cunningham, A.C.

    2011-01-01

    Geological evidence of storm surges has the potential to provide vital information on storm-surge risk. Sediment from the coastal dunes of the Netherlands contains evidence of extreme floods that occurred before reliable measurements of water level began. For these sediments to be useful in flood-ri

  5. Estimating nitrogen losses in furrow irrigated soil amended by compost using HYDRUS-2D model

    Science.gov (United States)

    Iqbal, Shahid; Guber, Andrey; Zaman Khan, Haroon; ullah, Ehsan

    2014-05-01

    Furrow irrigation commonly results in high nitrogen (N) losses from soil profile via deep infiltration. Estimation of such losses and their reduction is not a trivial task because furrow irrigation creates highly nonuniform distribution of soil water that leads to preferential water and N fluxes in soil profile. Direct measurements of such fluxes are impractical. The objective of this study was to assess applicability of HYDRUS-2D model for estimating nitrogen balance in manure amended soil under furrow irrigation. Field experiments were conducted in a sandy loam soil amended by poultry manure compost (PMC) and pressmud compost (PrMC) fertilizers. The PMC and PrMC contained 2.5% and 0.9% N and were applied at 5 rates: 2, 4, 6, 8 and 10 ton/ha. Plots were irrigated starting from 26th day from planting using furrows with 1x1 ridge to furrow aspect ratio. Irrigation depths were 7.5 cm and time interval between irrigations varied from 8 to 15 days. Results of the field experiments showed that approximately the same corn yield was obtained with considerably higher N application rates using PMC than using PrMC as a fertilizer. HYDRUS-2D model was implemented to evaluate N fluxes in soil amended by PMC and PrMC fertilizers. Nitrogen exchange between two pools of organic N (compost and soil) and two pools of mineral N (soil NH4-N and soil NO3-N) was modeled using mineralization and nitrification reactions. Sources of mineral N losses from soil profile included denitrification, root N uptake and leaching with deep infiltration of water. HYDRUS-2D simulations showed that the observed increases in N root water uptake and corn yields associated with compost application could not be explained by the amount of N added to soil profile with the compost. Predicted N uptake by roots significantly underestimated the field data. Good agreement between simulated and field-estimated values of N root uptake was achieved when the rate of organic N mineralization was increased

  6. Water Consumption and Maize Yield for Alternative Furrow Irrigation in Western Heilongjiang Province

    Institute of Scientific and Technical Information of China (English)

    SUN Aili; LI Yuexing; WEI Yongxia

    2010-01-01

    Aiming at less and un-uniform distribution rainfall problems, the serious draught in spring, low crop production and water efficiency in sandy soil area of Heilongjiang Province, the experiment of alternative furrow irrigation was conducted in Dumeng County in 2009. The purpose of the experiment was to find the water consumption law and its influence on maize yield. The results showed that the highest water consumption was during the heading stage and the highest daily consumption of water was during the filling stage. The stimulation effect of alternative furrow irrigation on yield was obvious in the that the seedling was 38.85 mm; the jointing was 108.11 mm; the heading was 124.39 mm; the filling was 88.96 mm; the milk was 60.21 mm; and the harvesting was 47.89 mm.

  7. Conductive surge testing of circuits and systems

    Science.gov (United States)

    Richman, P.

    1980-01-01

    Techniques are given for conductive surge testing of powered electronic equipment. The correct definitions of common and normal mode are presented. Testing requires not only spike-surge generators with a suitable range of open-circuit voltage and short-circuit current waveshapes, but also appropriate means, termed couplers, for connecting test surges to the equipment under test. Key among coupler design considerations is minimization of fail positives resulting from reduction in delivered surge energy due to the coupler. Back-filters and the lines on which they are necessary, are considered as well as ground-fault and ground potential rise. A method for monitoring delivered and resulting surge waves is mentioned.

  8. Development and Evaluation of Storm Surge Ensemble Forecasting for the Philippines Using JMA Storm Surge Model

    Science.gov (United States)

    Lapidez, J. P. B.; Tablazon, J. P.; Lagmay, A. M. F. A.; Suarez, J. K. B.; Santiago, J. T.

    2014-12-01

    The Philippines is one of the countries most vulnerable to storm surge. It is located in the North-western Pacific basin which is the most active basin in the planet. An average of 20 tropical cyclones enters the Philippine area of responsibility (PAR) every year. The archipelagic nature of the country with regions having gently sloping coasts and shallow bays also contribute to the formation of extreme surges. Last November 2013, storm surge brought by super typhoon Haiyan severely damaged several coastal regions in the Visayan Islands. Haiyan left more than 6 300 casualties and damages amounting to more than $ 2 billion. Extreme storm surge events such as this highlight the need to establish a storm surge early warning system for the country. This study explores the development and evaluation of storm surge ensemble forecasting for the Philippines using the Japan Meteorological Agency (JMA) storm surge model. 36-hour, 24-hour, and 12-hour tropical cyclone forecasts are used to generate an ensemble storm surge forecast to give the most probable storm surge height at a specific point brought by an incoming tropical cyclone. The result of the storm surge forecast is compared to tide gauge record to evaluate the accuracy. The total time of computation and dissemination of forecast result is also examined to assess the feasibility of using the JMA storm surge model for operational purposes.

  9. Surge dynamics in the Nathorstbreen glacier system, Svalbard

    Directory of Open Access Journals (Sweden)

    M. Sund

    2013-10-01

    Full Text Available Nathorstbreen glacier system (NGS recently experienced the largest surge in Svalbard since 1936, and is examined using spatial and temporal observations from DEM differencing, time-series of surface velocities from satellite synthetic aperture radar (SAR and other sources. The upper basins with maximum accumulation during quiescence correspond to regions of initial lowering. Initial speed-up exceeds quiescent velocities by a factor of several tens of times. This suggests that polythermal glaciers surges are initiated in the temperate area before mass is displaced downglacier. Subsequent downglacier mass displacement coincides with areas of 100–200 times increased velocities (stage 2. After > 5 yr the joint NGS terminus advanced abruptly into tidewater during winter. The advance was followed by upglacier propagation of crevasses, indicating a re-action following from the already displaced mass and extending flow. NGS advanced ca. 15 km, while another ca. 3 km length was lost due to calving. Surface lowering of ca. 50 m was observed in some upglacier areas and during 5 yr the total area increased by 20%. Maximum measured flow rates were at least 25 m d−1, 2500 times quiescence, while average velocities were about 10 m d−1. The surges of Zawadzkibreen cycle with ca. 70 yr periods.

  10. Evaluating models for the estimation of furrow irrigation infiltration and roughness

    Energy Technology Data Exchange (ETDEWEB)

    Ramezani Etedali, H.; Ebrahimian, H.; Abbasi, F.; Liaghat, A.

    2011-07-01

    Several methods have been proposed for estimating infiltration and roughness parameters in surface irrigation using mathematical models. The EVALUE, SIPAR{sub I}D, and INFILT models were used in this work. The EVALUE model uses a direct solution procedure, whereas the other two models are based on the inverse solution approach. The objective of this study is to evaluate the capacity of these models to estimate the Kostiakov infiltration parameters and the Manning roughness coefficient in furrow irrigation. Twelve data sets corresponding to blocked-end and free draining furrows were used in this work. Using the estimated parameters and the SIRMOD irrigation simulation software, the total infiltrated volume and recession time were predicted to evaluate the accuracy of the mathematical models. The EVALUE and SIPAR{sub I}D models provided the best performance, with EVALUE performing better than SIPAR{sub I}D for estimating the Manning roughness coefficient. The INFILT model provided lower accuracy in cut-back irrigation than in standard irrigation. The performance of SIPAR{sub I}D and INFILT in blocked-end and free draining furrows was similar. (Author) 28 refs.

  11. Cold Surge Activity Over the Gulf of Mexico in a Warmer Climate

    Directory of Open Access Journals (Sweden)

    Edgar Perez Perez

    2014-08-01

    Full Text Available Cold surges are a dominant feature of midlatitude tropical interaction. During the North Hemisphere (NH winter, midlatitude waves propagating from the Rocky Mountains into the Gulf of Mexico result in cold surges, also known as Nortes or Tehuantepecers, associated with severe weather over the southern part of Mexico. The magnitude of their intense surface winds, precipitation and drops in surface temperature depends on the characteristics of the midlatitude wave propagating into the tropics. The high spatial resolution (20km X 20km version of the TL959L60-AGC Model of the Meteorological Research Institute of Japan is used to examine changes in cold surge activity under the A1B greenhouse gas emission scenario for the 2080 - 2099 period. The model realistically reproduces the spatial and temporal characteristics of cold surges for the 1980 - 1989 control period. The effect of changes in baroclinicity, static stability and mean flow over North America suggest that in a warmer climate, increased cold surge activity over the Gulf of Mexico would occur. However, these systems would have shorter wavelength (higher phase speeds and shorter lifespans that could reduce the total amount of winter precipitation. The increased frequency of cold surges over the Gulf of Mexico would be a consequence of weaker baroclinicity and static stability in the lower troposphere over the cold surge genesis region, along with more dominant westerly winds, resulting from ENSO-like conditions in the atmospheric circulations over North America.

  12. Modelling of variable speed centrifugal compressors for anti-surge control

    OpenAIRE

    Aaslid, Per

    2009-01-01

    A mathematical model for simulation of gas compressor systems is developed. The model is designed for anti-surge control validation, and models a continuous flow gas compressor. The model also includes a cooler for gas cooling, a scrubber for liquid draining, and a recycle line with a control valve for anti-surge control. The system outlet has a check valve to prevent reversed flows. The model is one-dimensional and models pressure, temperature and mass flow for all system components, and als...

  13. Forces and straw cutting performance of double disc furrow opener in no-till paddy soil.

    Directory of Open Access Journals (Sweden)

    Fiaz Ahmad

    Full Text Available Conservation tillage is an energy efficient and low cost tillage system to improve soil environment compared with conventional tillage systems. However, the rice residue management becomes an "impossible to achieve" task due to high soil moisture content at harvest time and the thickness of rice straw. Disc type furrow openers are used for both seed drilling as well as straw cutting during no tillage sowing. A study was conducted to evaluate the draft requirement and straw cutting performances of different sized furrow openers in no-till paddy soil conditions. Double disc furrow opener was tested on an in-field traction bench for three working depths, i.e. 30, 60 and 90 mm, and three forwarding speeds, i.e. 0.1, 0.2 and 0.3 m/s. The draft and vertical forces on the disc were recorded with load cells. These sensors were connected to a data acquisition system developed with hardware and software. The results revealed that the size of the furrow opener, operating depth and the forwarding speed had significant effects (P<0.05 on the horizontal and vertical forces, and the straw cutting performance. Mean values of the draft were 648.9, 737.2 and 784.6 N for the opener with diameters of 330, 450 and 600 mm respectively, and the vertical forces for similar openers were 904.7, 1553.9 and 1620.4 N, respectively. Furthermore, the mean straw cutting efficiencies for the double disc opener with diameters of 330, 450 and 600 mm were 39.36, 78.47 and 65.46%, respectively. The opener with 450 mm diameter provided higher straw cutting efficiency as compared to 600 mm diameter disc, while lowest straw cutting efficiency was observed with 330 mm diameter disc. The 450 mm diameter opener provided the highest straw cutting efficiency (88.6% at 90 mm working depth and expressed optimum performance compared with other furrow openers.

  14. Using a Smart-phone for Collecting Discharge Data in Irrigation Furrows in Tanzania.

    Science.gov (United States)

    Pena-Haro, S.; Lüthi, B.; Philippe, T.; Naudascher, R.; Siegfried, T.

    2015-12-01

    When managed effectively and sustainably crop yield in irrigated agriculture can be up to three times than in rainfed agriculture. Unsurprisingly, irrigation agriculture is globally gaining in importance. This is especially true in Africa where the share of irrigated to rainfed agriculture in terms of area cultivated is below global averages. A large-scale expansion of irrigation, nonetheless has the potential to alter the natural hydrological cycle at local up to basin scales. In all cases, a good understanding of the water balance is needed. However, and especially in the developing context, data are scarce and knowledge about the available resources is most often not present. Some of the key reasons are: a) traditional monitoring approaches do not scale in terms of costs, b) repair is difficult and c) vandalism. There is a clear need of cheaper and easy-to-use methods for gathering information on water use and water availability.We have developed a mobile device application for measuring discharge in rivers and irrigation furrows. The discharge is computed by analysing a few seconds of a movie recorded using the built-in camera. The great advantage is that the only requirement is that the field of view contains two reference markers with known scale and with known position relative to the channel geometry, a priori knowledge on the channel geometry and its roughness. The other great advantage is that the data collected (water level, surface velocity and discharge) can be sent via SMS or web-service to a central database.The app is being currently used in a formerly ungauged catchment, the Themi River, which is part of the Pangani Basin in Tanzania. Furrow leaders and community members measure furrow discharges on-farm and monitor water levels in rivers off-farm. These community members were given a smartphone and received thorough training. Additionally, off-grid members have received a mobile recharging solution. Operational Expenses of the community members

  15. The dynamics of surge in compression systems

    Indian Academy of Sciences (India)

    A N Vishwanatha Rao; O N Ramesh

    2007-02-01

    In air-compression systems, instabilities occur during operation close to their peak pressure-rise capability. However, the peak efficiency of a compression system lies close to this region of instability. A surge is a violent mode of instability where there is total breakdown of flow in the system and pressure-rise capability is lost drastically. Generally, all compression systems operate with a margin defined as the ‘surge margin’, and, consequently, system operational efficiency is lower. It is of interest to study compression-system surge to understand its dynamics in order to operate compression systems close to the instability for achieving high efficiency safely without encountering surge. Unsteady pressure data from a compression system, captured during surge oscillations, reveal many aspects of flow physics and are analysed to understand the surge dynamics of the system. A set of controlled experiments was conducted with a simple desktop experimental test set-up and essential aspects of surge dynamics have been characterised.

  16. Storm surge and tidal range energy

    Science.gov (United States)

    Lewis, Matthew; Angeloudis, Athanasios; Robins, Peter; Evans, Paul; Neill, Simon

    2017-04-01

    The need to reduce carbon-based energy sources whilst increasing renewable energy forms has led to concerns of intermittency within a national electricity supply strategy. The regular rise and fall of the tide makes prediction almost entirely deterministic compared to other stochastic renewable energy forms; therefore, tidal range energy is often stated as a predictable and firm renewable energy source. Storm surge is the term used for the non-astronomical forcing of tidal elevation, and is synonymous with coastal flooding because positive storm surges can elevate water-levels above the height of coastal flood defences. We hypothesis storm surges will affect the reliability of the tidal range energy resource; with negative surge events reducing the tidal range, and conversely, positive surge events increasing the available resource. Moreover, tide-surge interaction, which results in positive storm surges more likely to occur on a flooding tide, will reduce the annual tidal range energy resource estimate. Water-level data (2000-2012) at nine UK tide gauges, where the mean tidal amplitude is above 2.5m and thus suitable for tidal-range energy development (e.g. Bristol Channel), were used to predict tidal range power with a 0D modelling approach. Storm surge affected the annual resource estimate by between -5% to +3%, due to inter-annual variability. Instantaneous power output were significantly affected (Normalised Root Mean Squared Error: 3%-8%, Scatter Index: 15%-41%) with spatial variability and variability due to operational strategy. We therefore find a storm surge affects the theoretical reliability of tidal range power, such that a prediction system may be required for any future electricity generation scenario that includes large amounts of tidal-range energy; however, annual resource estimation from astronomical tides alone appears sufficient for resource estimation. Future work should investigate water-level uncertainties on the reliability and

  17. Impact of Low-Level Southerly Surges on Mixed Rossby Gravity Waves over the Central Pacific.

    Science.gov (United States)

    Fukutomi, Y.

    2014-12-01

    This study examines dynamical impacts of lower-tropospheric southerly wind surges originating in midlatitudes of the Southern Hemisphere (SH) on the development of mixed Rossby gravity (MRG) waves over the central Pacific during June-August 1979-2012, through the statistical analysis of the JRA-55 products and NOAA outgoing long wave radiation data. The central Pacific MRG waves are identified by an extended EOF (EEOF) analysis on 2-8-day filtered daily 850-hPa meridional wind anomalies during June-August 1979-2012. Composite analysis based on the leading EEOF time coefficients is able to capture the development of the MRG waves associated with a southerly surge originating in the SH extratropics. As a weak clockwise gyre as a part of an off-equatorial easterly wavetrain moves eastward and southeastward from the off-equatorial eastern Pacific into the equatorial central Pacific, the southerly surge penetrates into the equatorial tropics at around 150W. Then, the clockwise gyre develops into a MRG-type gyre over the central Pacific. A transition from an easterly wave-type gyre into a MRG-type gyre occurs associated with the southerly surge. The southerly surge forms a cross-equatorial flow on the western flank of the MRG-type gyre. The gyre is amplified when the southerly surge reaches the equatorial tropics. At the same time, convection coupled with the MRG-type gyre is enhanced. The southerly surges are originated in the midlatitude South Pacific, and they are induced by synoptic-scale baroclinic disturbances propagating along the SH midlatitude westerly jet. An eddy vorticity budget analysis indicates that the southerly surge plays an important role in spinning up the MRG-type gyre through transient advection of absolute vorticiy. A case study of a MRG-wave event in mid-July 2006 also illustrates development of a MRG wave associated with the southerly surge and an easterly wave-to-MRG wave transition.

  18. Thermal structure of Svalbard glaciers and implications for thermal switch models of glacier surging

    Science.gov (United States)

    Sevestre, Heïdi; Benn, Douglas I.; Hulton, Nicholas R. J.; Bælum, Karoline

    2015-10-01

    Switches between cold- and warm-based conditions have long been invoked to explain surges of High Arctic glaciers. Here we compile existing and new data on the thermal regime of six glaciers in Svalbard to test the applicability of thermal switch models. Two of the large glaciers of our sample are water terminating while one is land terminating. All three have a well-known surge history. They have a thick basal layer of temperate ice, superimposed by cold ice. A cold terminus forms during quiescence but is mechanically removed by calving on tidewater glaciers. The other three glaciers are relatively small and are either entirely cold or have a diminishing warm core. All three bear evidence of former warm-based thermal regimes and, in two cases, surge-like behavior during the Little Ice Age. In Svalbard, therefore, three types of glaciers have switched from slow to fast flow: (1) small glaciers that underwent thermal cycles during and following the Little Ice Age (switches between cold- and warm-based conditions), (2) large terrestrial glaciers which remain warm based throughout the entire surge cycle but develop cold termini during quiescence, and (3) large tidewater glaciers that remain warm based throughout the surge cycle. Our results demonstrate that thermal switching cannot explain the surges of large glaciers in Svalbard. We apply the concept of enthalpy cycling to the spectrum of surge and surge-like behavior displayed by these glaciers and demonstrate that all Svalbard surge-type glaciers can be understood within a single conceptual framework.

  19. Physical attributes of hurricane surges and their role in surge warning

    Science.gov (United States)

    Irish, J. L.

    2012-12-01

    In the last decade, the US has experienced some of its largest surges and hurricane-related damages on record. Effective evacuation in advance of a hurricane strike requires accurate estimation of the hurricane surge hazard that effectively conveys risk not only to government decision makers but also to the general public. Two primary challenges exist with the current structure for surge warning. First, existing computational methods for developing accurate, quantitative surge forecasts, namely surge height and inundation estimation, are limited by time and computational resources. Second, due primarily to the popularity and wide use of the Saffir-Simpson wind scale to convey the complete hurricane hazard, the public's perception of surge hazard is inaccurate. Here, we use dimensionless scaling and hydrodynamics arguments to quantify the influence of hurricane variables and regional geographic characteristics on the surge response. It will be shown that hurricane surge primarily scales with the hurricane's central pressure, and size and with continental shelf width at the landfall location (Irish et al. 2009, Nat. Haz.; Song et al. in press, Nat. Haz.). Secondary influences include the hurricane's forward speed and path. The developed physical scaling is applied in two ways: (1) as a means for expanding the utility of computational simulations for real-time surge height forecasting and (2) as a means to convey relative surge hazard via a readily evaluated algebraic surge scale. In the first application, the use of this physical scaling to develop surge response functions (SRF) enables instantaneous algebraic calculation of maximum surge height at any location of interest for any hurricane meteorological condition, without loss of accuracy gained via high-resolution computational simulation. When coupled with joint probability statistics, the use of SRFs enables rapid development of continuous probability density functions for probabilistic surge forecasting (Irish

  20. Disturbance of Ultisol soil based on interactions between furrow openers and coulters for the no-tillage system

    Energy Technology Data Exchange (ETDEWEB)

    Francetto, T.R.; Alonço, A. dos S.; Brandelero, C.; Machado, O.D. da C.; Veit, A.A.; Carpes, D.P.

    2016-11-01

    The present study evaluated the effect of different associations between coulters and fertilizer furrow openers on soil disturbance, furrow depth and width, according to forward speed. The study was conducted on a farm in Santa Maria (Brazil/RS), in soil classified as sandy loam Ultisol. The experiment consisted of 24 combinations of treatments with three replications in a 2×3×4 factorial experiment. The combinations were formed by the interaction of the factors including: two types of furrow openers (hoe and double-disc), three types of coulters (no-coulter, smooth and offset fluted) and four levels of forward speed (1.11, 1.67, 2.22 and 2.78 m/s). Soil elevation and soil disturbance area profiles were obtained with the use of a micro profilometer, and disturbance values were calculated with the aid of computer software program Auto Cad. The disturbance area was not affected by speed; it was greater when using the hoe opener, and in association with the offset fluted coulter. Speed was inversely proportional to the depth of the furrows made by the hoe opener. Furthermore, the hoe caused the greatest furrow width (0.26 m) in comparison with the double-disc (0.24 m). The use of different coulters associated with furrow openers increased this variable (0.23 m for the no-coulter condition, 0.25 m with smooth and 0.26 m with offset fluted). The use of coulters combined with furrow openers reduces soil swelling, in approximately 8% for the smooth and 20% for the offset fluted. (Author)

  1. Experiment and surge analysis of centrifugal two-stage turbocharging system

    Institute of Scientific and Technical Information of China (English)

    Yituan HE; Chaochen MA

    2008-01-01

    To study a centrifugal two-stage turbocharging system's surge and influencing factors, a special test bench was set up and the system surge test was performed. The test results indicate that the measured parameters such as air mass flow and rotation speed of a high pressure (HP) stage compressor can be converted into corrected para-meters under a standard condition according to the Mach number similarity criterion, because the air flow in a HP stage compressor has entered the Reynolds number (Re) auto-modeling range. Accordingly, the reasons leading to a two-stage turbocharging system's surge can be analyzed according to the corrected mass flow characteristic maps and actual operating conditions of HP and low pressure (LP) stage compressors.

  2. New insights in the ongoing surge of the Austfonna icecap

    Science.gov (United States)

    Schellenberger, T.; Dunse, T.; Kääb, A.; Hagen, J. O.; Schuler, T.; Reijmer, C.

    2014-12-01

    Basin-3, a major drainage basin of the Austfonna icecap in NE-Svalbard switched to full surge mode in autumn 2012 after a multiannual, stepwise acceleration of its northern branch. A time series of velocity maps from repeat TerraSAR-X acquisitions revealed a maximum speed at the terminus of >18 m d-1 around the turn of the year 2012. The frontal ablation of Basin-3 was estimated to 4.2±1.6 Gt a-1 between April 2012 and May 2013, tripling the total dynamic mass loss from the largest icecap in the Eurasian arctic. Today, TerraSAR-X, Radarsat-2 and GPS data show that the surge is still ongoing. While the speed at the calving front dropped to 10 m d-1 until July 2014, areas further inland continued to accelerate after the climax, and 10 m d-1 were also measured ~20 km inland in summer 2014. This development will be further investigated by exploiting a time series of velocity maps based on Radarsat-2 Fine Beam data starting from July 2014, which will, other than the TerraSAR-X data, cover almost the entire fast flowing part of the basin. By combining both datasets we will extend the estimation of the frontal ablation and related sea-level rise contribution of the Basin-3 surge.

  3. Glacier surge mechanism: 1982-1983 surge of variegated glacier, alaska.

    Science.gov (United States)

    Kamb, B; Raymond, C F; Harrison, W D; Engelhardt, H; Echelmeyer, K A; Humphrey, N; Brugman, M M; Pfeffer, T

    1985-02-01

    The hundredfold speedup in glacier motion in a surge of the kind the kind that took place in Variegated Glacier in 1982-1983 is caused by the buildup of high water pressure in the basal passageway system, which is made possible by a fundamental and pervasive change in the geometry and water-transport characteristics of this system. The behavior of the glacier in surge has many remarkable features, which can provide clues to a detailed theory of the surging process. The surge mechanism is akin to a proposed mechanism of overthrust faulting.

  4. Artificial Neural Network forecasting of storm surge water levels at major estuarine ports to supplement national tide-surge models and improve port resilience planning

    Science.gov (United States)

    French, Jon; Mawdsley, Robert; Fujiyama, Taku; Achuthan, Kamal

    2017-04-01

    Effective prediction of tidal storm surge is of considerable importance for operators of major ports, since much of their infrastructure is necessarily located close to sea level. Storm surge inundation can damage critical elements of this infrastructure and significantly disrupt port operations and downstream supply chains. The risk of surge inundation is typically approached using extreme value analysis, while short-term forecasting generally relies on coastal shelf-scale tide and surge models. However, extreme value analysis does not provide information on the duration of a surge event and can be sensitive to the assumptions made and the historic data available. Also, whilst regional tide and surge models perform well along open coasts, their fairly coarse spatial resolution means that they do not always provide accurate predictions for estuarine ports. As part of a NERC Environmental Risks to Infrastructure Innovation Programme project, we have developed a tool that is specifically designed to forecast the North Sea storm surges on major ports along the east coast of the UK. Of particular interest is the Port of Immingham, Humber estuary, which handles the largest volume of bulk cargo in the UK including major flows of coal and biomass for power generation. A tidal surge in December 2013, with an estimated return period of 760 years, partly flooded the port, damaged infrastructure and disrupted operations for several weeks. This and other recent surge events highlight the need for additional tools to supplement the national UK Storm Tide Warning Service. Port operators are also keen to have access to less computationally expensive forecasting tools for scenario planning and to improve their resilience to actual events. In this paper, we demonstrate the potential of machine learning methods based on Artificial Neural Networks (ANNs) to generate accurate short-term forecasts of extreme water levels at estuarine North Sea ports such as Immingham. An ANN is

  5. An Investigation of Surge in a High-Speed Centrifugal Compressor Using Digital PIV

    Science.gov (United States)

    Wernet, Mark P.; Bright, Michelle M.; Skoch, Gary J.

    2002-01-01

    Compressor stall is a catastrophic breakdown of the flow in a compressor, which can lead to a loss of engine power, large pressure transients in the inlet/nacelle and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge can significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify the dynamic changes occurring in the flow field prior to rotating stall and surge in order to successfully control these events. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to simultaneously capture transient velocity and pressure measurements in the non-stationary flow field during compressor surge. DPIV is an instantaneous, planar measurement technique which is ideally suited for studying transient flow phenomena in high speed turbomachinery and has been used previously to successfully map the stable operating point flow field in the diffuser of a high speed centrifugal compressor. Through the acquisition of both DPIV images and transient pressure data, the time evolution of the unsteady flow during surge is revealed.

  6. Surge-tectonic evolution of southeastern Asia: a geohydrodynamics approach

    Science.gov (United States)

    Meyerhoff, Arthur A.

    the surge channels—form an anastomosing E-W pattern southern Asiatic Russia, Mongolia, western China, the Qinghai-Tibetan region, and northern India and Pakistan. Such an anastomosing pattern indicates that flow is an active process in the surge channels. Surface studies of phenomena that might be associated with the surge channels soon revealed that all active channels are characterized by higher-than-normal heat flow (> 55 mW m -2, thermal springs and elevated ground-water temperatures, volvanic phenomena, bands of microearthquakes, and linear belts of faults, fractures, and fissures. The latter are especially visible on satellite images. The bands of high heat flow, thermal springs, microearthquakes, and faults-fractures-fissures almost exactly coincide. The fault-fracture-fissure systems are interpreted to be streamlines caused by flow in the surge channels—a consequence of Stokes's Law (an expression of Newton's Second Law of Motion)-and show that Poiseuille flow must dominate in the channels. Hence, the mechanism producing the belts of linear faults-fractures-fissures is viscous drag, produced by fluid motions. The eastward flow of the magma in the channels is demonstrated clearly in the tectonic patterns of southeastern Asia. In the northern part of the region studied, the E-W striking anastomosing surge channels (tectonic belts) splay northeastward into the coastal regions of Russia. In the south, they splay southward and southeastward through the Malay Peninsula and Indonesia. The open horsetail structures thus created prove that flow is W-E. The presence of the two splay directions, NE and S-SE, indicates in addition that a barrier to eastward flow must lie directly east of Asia. In this author's opinion, this barrier is the existing Benioff zone, because the same NE and S-SE splay patterns are present on each of the paleotectonic maps that have been prepared for nine time intervals from the beginning of Sinian (latest Proterozoic) time to the present. The

  7. The maternal-effect gene cellular island encodes aurora B kinase and is essential for furrow formation in the early zebrafish embryo.

    Directory of Open Access Journals (Sweden)

    Taijiro Yabe

    2009-06-01

    Full Text Available Females homozygous for a mutation in cellular island (cei produce embryos with defects in cytokinesis during early development. Analysis of the cytoskeletal events associated with furrow formation reveal that these defects include a general delay in furrow initiation as well as a complete failure to form furrow-associated structures in distal regions of the blastodisc. A linkage mapping-based candidate gene approach, including transgenic rescue, shows that cei encodes the zebrafish Aurora B kinase homologue. Genetic complementation analysis between the cei mutation and aurB zygotic lethal mutations corroborate gene assignment and reveal a complex nature of the maternal-effect cei allele, which appears to preferentially affect a function important for cytokinesis in the early blastomeres. Surprisingly, in cei mutant embryos a short yet otherwise normal furrow forms in the center of the blastodisc. Furrow formation is absent throughout the width of the blastodisc in cei mutant embryos additionally mutant for futile cycle, which lack a spindle apparatus, showing that the residual furrow signal present in cei mutants is derived from the mitotic spindle. Our analysis suggests that partially redundant signals derived from the spindle and astral apparatus mediate furrow formation in medial and distal regions of the early embryonic blastomeres, respectively, possibly as a spatial specialization to achieve furrow formation in these large cells. In addition, our data also suggest a role for Cei/AurB function in the reorganization of the furrow-associated microtubules in both early cleavage- and somite-stage embryos. In accordance with the requirement for cei/aurB in furrow induction in the early cleavage embryo, germ plasm recruitment to the forming furrow is also affected in embryos lacking normal cei/aurB function.

  8. Model simulation of storm surge potential for Andaman islands

    Digital Repository Service at National Institute of Oceanography (India)

    Kumar, V.S.; RameshBabu, V.; Babu, M.T.; Dhinakaran, G.; Rajamanickam, G.V.

    ) for storm surge forecasting at the eastern coast of India. Flather (1994) has applied another analytical model of Holland (1980) for wind and pressure fields in the case of surge simulation, forced by April 1991 Bangladesh storm. The basic atmospheric... parameters remain the same in all the parameterization schemes of storm wind field. Storm Surge Model Storm surge operational models are in use for a long time for forecasting and warning of storm surge disasters bordering the coasts in the parts of northern...

  9. Investigating changes in basal conditions of Variegated Glacier prior and during its 1982–1983 surge

    Directory of Open Access Journals (Sweden)

    O. Gagliardini

    2011-05-01

    Full Text Available The Variegated Glacier (Alaska is known to surge periodically after a sufficient amount of cumulative mass balance is reached, but this observation is difficult to link with changes in the basal conditions. Here, using a 10-year dataset, consisting in surface topography and surface velocity observations along a flow line for 25 dates, we have reconstructed the evolution of the basal conditions prior and during the 1982–1983 surge. The model solves the full-Stokes problem along the central flow line using the finite element method. For the 25 dates of the dataset, the basal friction parameter distribution is inferred using the inverse method proposed by Arthern and Gudmundson (2010. This method is here slightly modified by incorporating a regularisation term in the cost function to avoid short wave length changes in the friction parameter. Our results indicate that dramatic changes in the basal conditions occurred between 1973 to 1983. Prior to the surge, periodical changes can be observed between winter and summer, with a regular increase of the sliding from 1973 to 1982. During the surge, the basal friction decreased dramatically and an area of very low friction moved from the upper part of the glacier to its terminus. Using a more complex friction law, these changes in basal sliding are then interpreted in terms of basal water pressure. It confirms that dramatic changes took place in the subglacial drainage system of Variegated Glacier, moving from a relatively efficient drainage system prior to the surge to an inefficient one during the surge. By reconstructing the water pressure evolution at the base of the glacier it is possible to infer realistic scenarios for the hydrological history leading to the occurrence of a surge.

  10. On the possibility of convective overturning in the Słupsk Furrow overflow of the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Victor Zhurbas

    2011-09-01

    Full Text Available Alosely spaced CTD transects across the Slupsk Furrow displayed a "downward-bending" of salinity contours below the salinity interface on the southern flank due to a transverse circulation in the saline water overflow. Numerical simulation of a gravity current in an idealized channel with geometry, dimensions and initial density stratification all much the same as in the Slupsk Furrow was applied to verify whether the downward-bending could be transformed into an inverted density stratification. Some arguments in favour of the possibility of convective overturning due to the differential transverse advection beneath the gravity current, brought on by the numerical simulations, are discussed.

  11. Sedimentological features of the surge emitted during the August, 2006 pyroclastic eruption at Tungurahua volcano (Ecuador)

    Science.gov (United States)

    Douillet, G.; Goldstein, F.; Lavallee, Y.; Hanson, J. B.; Kueppers, U.; Robin, C.; Ramon, P.

    2009-12-01

    Tungurahua volcano, Ecuador, is a stratovolcano, which began a new eruptive phase in 1999. Notable pyroclastic Density Currents (PDC) were generated in July (VEI 2) and August (VEI 3) 2006 and covered its N and W flanks. PDCs and associated lahars represent a major hazard for 20,000 inhabitants and an hydrological dam. The volcano has been monitored by the Instituto Geofisico of the Escuela Politécnica Nacional of Quito, since 1988. Field work carried out in 2009 provide information on the behavior of the fine-grained fraction of the PDC (i.e., surge) during transport and deposition. We mapped out the sedimentological characteristics of the deposits and distinguished three depositional environments: 1- The core of the deposit, up to several m in thickness, is confined to valleys and consists of poorly-sorted lapilli scoria and blocks (cm to m scale) and a small fraction of ash matrix. Ongoing analysis of the ash matrix will help to understand the link between the main PDC and the associated surge. 2- On ridges and outer margins of valleys, the deposits total a thickness of 10s to 100s cm and consist of fine- to coarse-grain ashes organized in cm-scale beds. Horizontal to cross bed laminations with 10-cm long wavelength prevail. They are typical of deposition under sustained high-energy current, which we associate with the flow of a surge. 3- In the distal part of surge deposits, we observe fine grained surge deposits with a thickness up to ca. 5 m. The characteristic structures are curved crested dunes, 10s of cm high and up to 10s of m long, with dip angles ranging from 15 to 35° and a strongly asymmetric shape. The steepest side tends to be the upslope face. Dunes show mainly a climbing structure, with beds cm in thickness, but some are more complicated, containing cut and fill structures, interpreted as late-stage pulses of energetic turbulence. No displacement dunes were observed in this area. Using the flow direction given by 100s of dunes, we provide

  12. The optimization of design parameters for surge relief valve for pipeline systems

    Science.gov (United States)

    Kim, Hyunjun; Hur, Jisung; Kim, Sanghyun

    2017-06-01

    Surge is an abnormal pressure which induced by rapid changes of flow rate in pipeline systems. In order to protect pipeline system from the surge pressure, various hydraulic devices have been developed. Surge-relief valve(SRV) is one of the widely applied devices to control surge due to its feasibility in application, efficiency and cost-effectiveness. SRV is designed to automatically open under abnormal pressure and discharge the flow and makes pressure of the system drop to the allowable level. The performance of the SRV is influenced by hydraulics. According to previous studies, there are several affecting factors which determine performance of the PRV such as design parameters (e.g. size of the valve), system parameters (e.g. number of the valves and location of the valve), and operation parameters (e.g. set point and operation time). Therefore, the systematic consideration for factors affecting performance of SRV is required for the proper installation of SRV in the system. In this study, methodology for finding optimum parameters of the SRV is explored through the integration of Genetic Algorithm(GA) into surge analysis.

  13. Changes in the Earth's largest surge glacier system from satellite and airborne altimetry and imagery

    Science.gov (United States)

    Trantow, T.; Herzfeld, U. C.

    2015-12-01

    The Bering-Bagley Glacier System (BBGS), Alaska, one of the largest ice systems outside of Greenland and Antarctica, has recently surged (2011-2013), providing a rare opportunity to study the surge phenomenon in a large and complex system. Understanding fast-flowing glaciers and accelerations in ice flow, of which surging is one type, is critical to understanding changes in the cryosphere and ultimately changes in sea level. It is important to distinguish between types of accelerations and their consequences, especially between reversible or quasi-cyclic and irreversible forms of glacial acceleration, but current icesheet models treat all accelerating ice identically. Additionally, the surge provides an exceptional opportunity to study the influence of surface roughness and water content on return signals of altimeter systems. In this presentation, we analyze radar and laser altimeter data from CryoSat-2, NASA's Operation IceBridge (OIB), the ICESat Geoscience Laser Altimeter System (GLAS), ICESat-2's predecessor the Multiple Altimeter Beam Experimental Lidar (MABEL), and airborne laser altimeter and imagery campaigns by our research group. These measurements are used to study elevation, elevation change and crevassing throughout the glacier system. Analysis of the imagery from our airborne campaigns provides comprehensive characterizations of the BBGS surface over the course of the surge. Results from the data analysis are compared to numerical modeling experiments.

  14. Change of the Microstructure of ZnO Arrester Block by Lightning Surge Current and Ageing Test

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Bok Hee; Kang, Sung Man [Inha University (Korea)

    2000-07-01

    This paper deals with the change of the micro-structure of ZnO associated with lightning surge current and ageing test. In this work, a surge current generator which can produce 8/20 [{mu}s],6 [kA] impulse current is designed and fabricated to simulate the lightning impulse current. The residual voltage and leakage current flowing to ZnO blocks are observed. Also a compensation circuit was used in resistive current measurement. The micro-structures of ZnO arrester block were significantly changed by lightning surge current and accelerated temperature ageing test. (author). 6 refs., 7 figs., 1 tab.

  15. From solitary wave to traveling surge

    Institute of Scientific and Technical Information of China (English)

    宋礼庭

    1995-01-01

    The solution of kinetic Alfven wave under action of anomalous resistance has two branches: the slow wave, VPsurge and the fast wave VP>VA cosθ will be in a wave-broken state. Such traveling surge structure is a typical self-organization phenomenon and its wave form is determined by parameter β which represents the magnitude of resistance. High β leads to shock-like structure and low β to the appearance of some solitary waves in front of the shock. According to the study on solitary wave, shock wave and traveling surge in conjunction with self-organization of nonlinear dynamics, a general definition of wave can be given.

  16. Adaptive mesh refinement for storm surge

    KAUST Repository

    Mandli, Kyle T.

    2014-03-01

    An approach to utilizing adaptive mesh refinement algorithms for storm surge modeling is proposed. Currently numerical models exist that can resolve the details of coastal regions but are often too costly to be run in an ensemble forecasting framework without significant computing resources. The application of adaptive mesh refinement algorithms substantially lowers the computational cost of a storm surge model run while retaining much of the desired coastal resolution. The approach presented is implemented in the GeoClaw framework and compared to ADCIRC for Hurricane Ike along with observed tide gauge data and the computational cost of each model run. © 2014 Elsevier Ltd.

  17. Adaptive Mesh Refinement for Storm Surge

    CERN Document Server

    Mandli, Kyle T

    2014-01-01

    An approach to utilizing adaptive mesh refinement algorithms for storm surge modeling is proposed. Currently numerical models exist that can resolve the details of coastal regions but are often too costly to be run in an ensemble forecasting framework without significant computing resources. The application of adaptive mesh refinement algorithms substantially lowers the computational cost of a storm surge model run while retaining much of the desired coastal resolution. The approach presented is implemented in the \\geoclaw framework and compared to \\adcirc for Hurricane Ike along with observed tide gauge data and the computational cost of each model run.

  18. Influence of Closing Storm Surge Barrier on Extreme Water Levels and Water Exchange; The Limfjord, Denmark

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Quvang Harck; Bentzen, Thomas Ruby; Larsen, Torben;

    2014-01-01

    of the fjord. The reduction is obtained by blocking the ingoing flow with a sluice in due time before the storm surge peaks in the North Sea. In order to avoid problems with reduced water quality and salinity, the water exchange should be controlled by only keeping the sluice open for ingoing currents...... the increased risk of flooding in the estuary has revitalized the discussion whether this connection should be closed. In this paper, it is shown by numerical simulation that the establishment of a storm surge barrier across Thyborøn Channel can significantly reduce the peak water levels in the central...

  19. Mitigation of hurricane storm surge impacts: Modeling scenarios over wide continental shelves

    Science.gov (United States)

    Lima Rego, Joao; Li, Chunyan

    2010-05-01

    The improvement of present understanding of surge dynamics over wide and shallow shelves is vital for the improvement of our ability to forecast storm surge impacts to coastal regions, particularly the low-lying land areas that are most vulnerable to hurricane flooding (e.g. the Northern Gulf of Mexico, coastal Bangladesh, the Southeast China sea). Given the increase of global sea-surface temperature, both the total number and proportion of intense tropical cyclones have increased notably since 1970 (Emanuel, 2005; Nature). Therefore, more intense hurricanes may hit densely populated coastal regions, and this problem may be aggravated by the prospect of accelerated sea-level rise in the 21st century. This presentation offers a review of recent work on hurricane-induced storm surge. The finite-volume coastal ocean model ("FVCOM", by Chen et al., 2003; J. Atmos. Ocean Tech.) was applied to the storm surge induced by Hurricanes Rita and Ike along the coasts of Louisiana and Texas in 2005 and 2008, respectively, to study coastal storm surge dynamics. The sensitivity analysis of Rego and Li (2009; Geophys. Res. Lett.) demonstrated how stronger, wider or faster tropical cyclones would affect coastal flooding. Li, Weeks and Rego (2009; Geophys. Res. Lett) looked into how hurricane flooding and receding dynamics differ, concluding that the overland flow in the latter stage is of considerable importance. Rego and Li (2010; J. Geophys. Res.) showed how extreme events may result of a combination of non-extreme factors, by studying the nonlinear interaction of tide and hurricane surge. The ability of models to reproduce these extreme events and to proactive plan for damage reduction is covered in Rego and Li's (2010; J. Marine Syst.) study of how barrier island systems protect coastal bays from offshore surge propagation. Here we combine these results for a wider perspective on how hurricane flooding could be mitigated under changing conditions.

  20. PH Domain-Arf G Protein Interactions Localize the Arf-GEF Steppke for Cleavage Furrow Regulation in Drosophila.

    Directory of Open Access Journals (Sweden)

    Donghoon M Lee

    Full Text Available The recruitment of GDP/GTP exchange factors (GEFs to specific subcellular sites dictates where they activate small G proteins for the regulation of various cellular processes. Cytohesins are a conserved family of plasma membrane GEFs for Arf small G proteins that regulate endocytosis. Analyses of mammalian cytohesins have identified a number of recruitment mechanisms for these multi-domain proteins, but the conservation and developmental roles for these mechanisms are unclear. Here, we report how the pleckstrin homology (PH domain of the Drosophila cytohesin Steppke affects its localization and activity at cleavage furrows of the early embryo. We found that the PH domain is necessary for Steppke furrow localization, and for it to regulate furrow structure. However, the PH domain was not sufficient for the localization. Next, we examined the role of conserved PH domain amino acid residues that are required for mammalian cytohesins to bind PIP3 or GTP-bound Arf G proteins. We confirmed that the Steppke PH domain preferentially binds PIP3 in vitro through a conserved mechanism. However, disruption of residues for PIP3 binding had no apparent effect on GFP-Steppke localization and effects. Rather, residues for binding to GTP-bound Arf G proteins made major contributions to this Steppke localization and activity. By analyzing GFP-tagged Arf and Arf-like small G proteins, we found that Arf1-GFP, Arf6-GFP and Arl4-GFP, but not Arf4-GFP, localized to furrows. However, analyses of embryos depleted of Arf1, Arf6 or Arl4 revealed either earlier defects than occur in embryos depleted of Steppke, or no detectable furrow defects, possibly because of redundancies, and thus it was difficult to assess how individual Arf small G proteins affect Steppke. Nonetheless, our data show that the Steppke PH domain and its conserved residues for binding to GTP-bound Arf G proteins have substantial effects on Steppke localization and activity in early Drosophila embryos.

  1. PH Domain-Arf G Protein Interactions Localize the Arf-GEF Steppke for Cleavage Furrow Regulation in Drosophila.

    Science.gov (United States)

    Lee, Donghoon M; Rodrigues, Francisco F; Yu, Cao Guo; Swan, Michael; Harris, Tony J C

    2015-01-01

    The recruitment of GDP/GTP exchange factors (GEFs) to specific subcellular sites dictates where they activate small G proteins for the regulation of various cellular processes. Cytohesins are a conserved family of plasma membrane GEFs for Arf small G proteins that regulate endocytosis. Analyses of mammalian cytohesins have identified a number of recruitment mechanisms for these multi-domain proteins, but the conservation and developmental roles for these mechanisms are unclear. Here, we report how the pleckstrin homology (PH) domain of the Drosophila cytohesin Steppke affects its localization and activity at cleavage furrows of the early embryo. We found that the PH domain is necessary for Steppke furrow localization, and for it to regulate furrow structure. However, the PH domain was not sufficient for the localization. Next, we examined the role of conserved PH domain amino acid residues that are required for mammalian cytohesins to bind PIP3 or GTP-bound Arf G proteins. We confirmed that the Steppke PH domain preferentially binds PIP3 in vitro through a conserved mechanism. However, disruption of residues for PIP3 binding had no apparent effect on GFP-Steppke localization and effects. Rather, residues for binding to GTP-bound Arf G proteins made major contributions to this Steppke localization and activity. By analyzing GFP-tagged Arf and Arf-like small G proteins, we found that Arf1-GFP, Arf6-GFP and Arl4-GFP, but not Arf4-GFP, localized to furrows. However, analyses of embryos depleted of Arf1, Arf6 or Arl4 revealed either earlier defects than occur in embryos depleted of Steppke, or no detectable furrow defects, possibly because of redundancies, and thus it was difficult to assess how individual Arf small G proteins affect Steppke. Nonetheless, our data show that the Steppke PH domain and its conserved residues for binding to GTP-bound Arf G proteins have substantial effects on Steppke localization and activity in early Drosophila embryos.

  2. Field performance of alternate wetting and drying furrow irrigation on tomato crop growth, yield, water use efifciency, quality and proiftability

    Institute of Scientific and Technical Information of China (English)

    Khokan Kumer Sarker; M A R Akanda; S K Biswas; D K Roy; A Khatun; M A Goffar

    2016-01-01

    Sustainable irrigation method is now essential for adaptation and adoption in the areas where water resources are limited. Therefore, a ifeld experiment was conducted to test the performance of alternate wetting and drying furrow irrigation (AWDFI) on crop growth, yield, water use efifciency (WUE), fruit quality and proiftability analysis of tomato. The experiment was laid out in randomized complete block design with six treatments replicated thrice during the dry seasons of 2013-2014 and 2014-2015. Irrigation water was applied through three ways of furrow: AWDFI, ifxed wetting and drying furrow irrigation (FWDFI) and traditional (every) furrow irrigation (TFI). Each irrigation method was divided into two levels: irrigation up to 100 and 80% ifeld capacity (FC). Results showed that plant biomass (dry matter) and marketable fruit yield of tomato did not differ signiifcantly between the treatments of AWDFI and TFI, but signiifcant difference was observed in AWDFI and in TFI compared to FWDFI at same irrigation level. AWDFI saved irrigation water by 35 to 38% for the irrigation levels up to 80 and 100% FC, compared to the TFI, respectively. AWDFI improved WUE by around 37 to 40% compared to TFI when irrigated with 100 and 80% FC, respectively. Fruit quality (total soluble solids and pulp) was found greater in AWDFI than in TFI. Net return from AWDFI technique was found nearly similar compared to TFI and more than FWDFI. The beneift cost ratio was viewed higher in AWDFI than in TFI and FWDFI by 2.8, 8.7 and 11, 10.4% when irrigation water was applied up to 100 and 80% FC, respectively. Unit production cost was obtained lower in AWDFI compared to TFI and FWDFI. However, AWDFI is a useful water-saving furrow irrigation technique which may resolve as an alternative choice compared with TFI in the areas where available water and supply methods are limited to irrigation.

  3. Soil Erosion as Affected by Polyacrylamide Application Under Simulated Furrow Irrigation with Saline Water

    Institute of Scientific and Technical Information of China (English)

    DOU Chao-Yin; LI Fa-Hu; L. S.WU

    2012-01-01

    The reduction of soil and water losses under furrow.irrigation with saline water is important to environnental protection and agricultural production.The objective of this study was to determine the effect of polyacrylamide (pAM) application on soil infiltration and erosion under simulated furrow irrigation with saline water.Polyacrylamide was applied by dissolving it in irrigation water at the rates of 1.5,7.5,and 15.0 mg L-1 or spreading it as a powder on soil surface at the rates of 0.3,15,3.0,and 6.0 g m-2,respectively.The electrolyte concentration of tested irrigation water was 10 and 30 mmolc L-1 and its sodium adsorption ratio (SAR) was 0.5,10.0,and 20.0 (mmol(c) L-1)0.5.Distilled water was used as a control for irrigation water quality.Results indicated that the electrolyte concentration and SAR generally did not significantly affect soil and water losses after PAM application.Infiltration rate and total infiltration volume decreased with the increase of PAM application rate.Polyacrylamide application in both methods significantly reduced soil erosion,but PAM application rate did not significantly affect it.The solution PAM application was more effective in controlling soil erosion than the powdered PAM application,but the former exerted a greater adverse influence on soil infiltration than the latter.Under the same total amounts,the powdered PAM application resulted in a 38.2%-139.6% granter infiltration volume but a soil mass loss of 1.3-3.4 times greater than the solution PAM apllication.

  4. Synthetic Fentanyl Fueling Surge in Overdose Deaths: CDC

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_160618.html Synthetic Fentanyl Fueling Surge in Overdose Deaths: CDC U.S. Surgeon ... News) -- Deaths from overdoses of the synthetic narcotic fentanyl have surged in recent years, U.S. health officials ...

  5. Approximate Nonlinear Modeling of Aircraft Engine Surge Margin Based on Equilibrium Manifold Expansion

    Institute of Scientific and Technical Information of China (English)

    LIU Xiaofeng; ZHAO Lei

    2012-01-01

    Stable operation of aircraft engine compressions is constrained by rotating surge.In this paper,an approximate nonlinear surge margin model of aircraft engine compression system by using equilibrium manifold is presented.Firstly,this paper gives an overview of the current state of modeling aerodynamic flow instabilities in engine compressors.Secondly,the expansion form of equilibrium manifold is introduced,and the choosing scheduling variable method is discussed.Then,this paper also gives the identification procedure of modeling the approximate nonlinear model.Finally,the modeling and simulations with high pressure (HP) compressor surge margin of the aircraft engine show that this real-time model has the same accuracy with the thermodynamic model,but has simpler structure and shorter computation time.

  6. A new on-line leakage current monitoring system of ZnO surge arresters

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Bok-Hee [Research Center for Next-Generation High Voltage and Power Technology, Inha University, 253 Yonghyun-dong, Nam-ku, Incheon 402-751 (Korea, Republic of)]. E-mail: bhlee@inha.ac.kr; Kang, Sung-Man [Research Center for Next-Generation High Voltage and Power Technology, Inha University, 253 Yonghyun-dong, Nam-ku, Incheon 402-751 (Korea, Republic of)

    2005-05-15

    This paper presents a new on-line leakage current monitoring system of zinc oxide (ZnO) surge arresters. To effectively diagnose the deterioration of ZnO surge arresters, a new algorithm and on-line leakage current detection device, which uses the time-delay addition method, for discriminating the resistive and capacitive currents was developed to use in the aging test and durability evaluation for ZnO arrester blocks. A computer-based measurement system of the resistive leakage current, the on-line monitoring device can detect accurately the leakage currents flowing through ZnO surge arresters for power frequency ac applied voltages. The proposed on-line leakage current monitoring device of ZnO surge arresters is more highly sensitive and gives more linear response than the existing devices using the detection method of the third harmonic leakage currents. Therefore, the proposed leakage current monitoring device can be useful for predicting the defects and performance deterioration of ZnO surge arresters in power system applications.

  7. Probabilistic modelling of sea surges in coastal urban areas

    Science.gov (United States)

    Georgiadis, Stylianos; Jomo Danielsen Sørup, Hjalte; Arnbjerg-Nielsen, Karsten; Nielsen, Bo Friis

    2016-04-01

    Urban floods are a major issue for coastal cities with severe impacts on economy, society and environment. A main cause for floods are sea surges stemming from extreme weather conditions. In the context of urban flooding, certain standards have to be met by critical infrastructures in order to protect them from floods. These standards can be so strict that no empirical data is available. For instance, protection plans for sub-surface railways against floods are established with 10,000 years return levels. Furthermore, the long technical lifetime of such infrastructures is a critical issue that should be considered, along with the associated climate change effects in this lifetime. We present a case study of Copenhagen where the metro system is being expanded at present with several stations close to the sea. The current critical sea levels for the metro have never been exceeded and Copenhagen has only been severely flooded from pluvial events in the time where measurements have been conducted. However, due to the very high return period that the metro has to be able to withstand and due to the expectations to sea-level rise due to climate change, reliable estimates of the occurrence rate and magnitude of sea surges have to be established as the current protection is expected to be insufficient at some point within the technical lifetime of the metro. The objective of this study is to probabilistically model sea level in Copenhagen as opposed to extrapolating the extreme statistics as is the practice often used. A better understanding and more realistic description of the phenomena leading to sea surges can then be given. The application of hidden Markov models to high-resolution data of sea level for different meteorological stations in and around Copenhagen is an effective tool to address uncertainty. For sea surge studies, the hidden states of the model may reflect the hydrological processes that contribute to coastal floods. Also, the states of the hidden Markov

  8. Active surge control of centrifugal compression systems : Theoretical and experimental results of drive actuation

    OpenAIRE

    Bøhagen, Bjørnar

    2007-01-01

    This thesis addresses modeling and active surge control of a simple compression system, using only the drive system of the compressor for actuation. Theoretical results are validated by experiments on a test rig that was built as a part of this work. Control laws are derived in two stages. First all system states, such as pressure mass flow and impeller speed, are assumed as available signals. All the resulting control laws require feedback from mass flow. However, transient measurement of th...

  9. 30 CFR 77.209 - Surge and storage piles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Surge and storage piles. 77.209 Section 77.209... Installations § 77.209 Surge and storage piles. No person shall be permitted to walk or stand immediately above a reclaiming area or in any other area at or near a surge or storage pile where the...

  10. Numerical Evaluation of Storm Surge Indices for Public Advisory Purposes

    Science.gov (United States)

    Bass, B.; Bedient, P. B.; Dawson, C.; Proft, J.

    2016-12-01

    After the devastating hurricane season of 2005, shortcomings with the Saffir-Simpson Hurricane Scale's (SSHS) ability to characterize a tropical cyclones potential to generate storm surge became widely apparent. As a result, several alternative surge indices were proposed to replace the SSHS, including Powell and Reinhold's Integrated Kinetic Energy (IKE) factor, Kantha's Hurricane Surge Index (HSI), and Irish and Resio's Surge Scale (SS). Of the previous, the IKE factor is the only surge index to-date that truly captures a tropical cyclones integrated intensity, size, and wind field distribution. However, since the IKE factor was proposed in 2007, an accurate assessment of this surge index has not been performed. This study provides the first quantitative evaluation of the IKEs ability to serve as a predictor of a tropical cyclones potential surge impacts as compared to other alternative surge indices. Using the tightly coupled ADvanced CIRCulation and Simulating WAves Nearshore models, the surge and wave responses of Hurricane Ike (2008) and 78 synthetic tropical cyclones were evaluated against the SSHS, IKE, HSI and SS. Results along the upper TX coast of the Gulf of Mexico demonstrate that the HSI performs best in capturing the peak surge response of a tropical cyclone, while the IKE accounting for winds greater than tropical storm intensity (IKETS) provides the most accurate estimate of a tropical cyclones regional surge impacts. These results demonstrate that the appropriate selection of a surge index ultimately depends on what information is of interest to be conveyed to the public and/or scientific community.

  11. Projections of extreme storm surge levels along Europe

    Science.gov (United States)

    Vousdoukas, Michalis I.; Voukouvalas, Evangelos; Annunziato, Alessandro; Giardino, Alessio; Feyen, Luc

    2016-11-01

    Storm surges are an important coastal hazard component and it is unknown how they will evolve along Europe's coastline in view of climate change. In the present contribution, the hydrodynamic model Delft3D-Flow was forced by surface wind and atmospheric pressure fields from a 8-member climate model ensemble in order to evaluate dynamics in storm surge levels (SSL) along the European coastline (1) for the baseline period 1970-2000; and (2) during this century under the Representative Concentration Pathways RCP4.5 and RCP8.5. Validation simulations, spanning from 2008 to 2014 and driven by ERA-Interim atmospheric forcing, indicated good predictive skill (0.06 m relative sea level rise (RSLR), can be further enforced by an increase of the extreme SSL, which can exceed 30 % of the RSLR, especially for the high return periods and pathway RCP8.5. This implies that the combined effect could increase even further anticipated impacts of climate change for certain European areas and highlights the necessity for timely coastal adaptation and protection measures. The dataset is publicly available under this link: http://data.jrc.ec.europa.eu/collection/LISCOAST.

  12. Avoiding compressor surge during emergency shutdown hybridturbine systems

    Energy Technology Data Exchange (ETDEWEB)

    Pezzini, Paolo [University of Genova, Italy; Tucker, David [U.S. DOE; Traverso, Alberto [University of Genova, Italy

    2013-01-01

    A new emergency shutdown procedure for a direct-fired fuel cell turbine hybrid power system was evaluated using a hardware-based simulation of an integrated gasifier/fuel cell/turbine hybrid cycle (IGFC), implemented through the Hybrid Performance (Hyper) project at the National Energy Technology Laboratory, U.S. Department of Energy (NETL). The Hyper facility is designed to explore dynamic operation of hybrid systems and quantitatively characterize such transient behavior. It is possible to model, test, and evaluate the effects of different parameters on the design and operation of a gasifier/fuel cell/gas turbine hybrid system and provide a means of quantifying risk mitigation strategies. An open-loop system analysis regarding the dynamic effect of bleed air, cold air bypass, and load bank is presented in order to evaluate the combination of these three main actuators during emergency shutdown. In the previous Hybrid control system architecture, catastrophic compressor failures were observed when the fuel and load bank were cut off during emergency shutdown strategy. Improvements were achieved using a nonlinear fuel valve ramp down when the load bank was not operating. Experiments in load bank operation show compressor surge and stall after emergency shutdown activation. The difficulties in finding an optimal compressor and cathode mass flow for mitigation of surge and stall using these actuators are illustrated.

  13. Remote-sensing-based analysis of the 1996 surge of Northern Inylchek Glacier, central Tien Shan, Kyrgyzstan

    Science.gov (United States)

    Häusler, Hermann; Ng, Felix; Kopecny, Alexander; Leber, Diethard

    2016-11-01

    The evolution of Northern Inylchek Glacier and its proglacial lake - Upper Lake Merzbacher - during its 1996 surge and the surrounding decades is analyzed with remote sensing imagery. Overall retreat of the glacier from 1943 to 1996 enlarged the lake to 4 km long and ≈ 100 m deep. The surge in 1996 initiated between 12 September and 7 October and advanced the glacier by 3.7 km to override most of Upper Lake Merzbacher. The surge phase probably ended in December 1996 and involved mean flow velocities across the lower trunk of the glacier that reached 50 m d- 1 over a 32-day period. Water displaced by the surge from Upper Lake Merzbacher, totalling 1.5 × 108 m3 in volume, accelerated filling of Lower Lake Merzbacher downvalley and helped trigger this marginal ice-dammed lake to outburst in a jökulhlaup around late November/early December. The characteristics and duration of the surge render it as similar to temperate glacier surges elsewhere. It may have been facilitated by low basal friction caused by water-saturated sediments in the upper lake bed. Furthermore, bathymetric measurements show that the surge evacuated much sediment into the upper lake, causing its depth to reduce from 20 to 30 m in 1996 to 8 m by 2005 and 2 m by 2011; the corresponding deposition rates imply glacier-catchment specific mean sediment yields of 1.4 to 3.4 × 103 Mg km- 2 a- 1 in the years after the surge. Our study documents novel interactions within a cascade system of glaciers and lakes that exhibits surging and outburst-flood behavior.

  14. NUMERICAL STUDY OF WATER LEVEL FLUCTUATION IN BULL-HORN SURGE CHAMBER IN PIPE SYSTEM DURING WATERHAMMER

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The method of characteristics was adopted to analyze water level fluctuation existing in Bull-Horn surge chamber in reservoir-valve pipe system during waterhammer caused by valve closure operation. The Finite Difference Method (FDM) based on the method of characteristics was used to solve numerically the nonlinear two-parameter characteristic equations governing waterhammer. The finite fixed mesh was applied to obtaining the discrete form of the governing equations and discrete flow-field. The temporal trends of the y-directional flow, water level, velocity of water level and head difference for different heights of water in surge chamber, diameters of cylinder, cutting angles of surge chamber, lengths of horizontal cylinder and lengths of inclined cylinder were obtained under the condition that the air in surge chamber is compressible. The conclusions on water level fluctuation in Bull-Horn surge chamber were given based on the analyses of the obtained transient numerical results. These conclusions can play a guiding role in designing pipe system and executing surge suppression.

  15. Impacts of land cover changes on hurricane storm surge in the lower Chesapeake Bay

    Science.gov (United States)

    Denton, M.; Lawler, S.; Ferreira, C.

    2013-12-01

    The Chesapeake Bay is the largest estuary in the United States with more than 150 rivers draining into the bay's tidal wetlands. Coastal wetlands and vegetation play an important role in shaping the hydrodynamics of storm surge events by retaining water and slowing the propagation of storm surge. In this way coastal wetlands act as a natural barrier to inland flooding, particularly against less intense storms. Threats to wetlands come from both land development (residential or commercial/industrial) and sea level rise. The lower region of the Chesapeake Bay near its outlet is especially vulnerable to flooding from Atlantic storm surge brought in by hurricanes, tropical storms and nor'easters (e.g., hurricanes Isabel [2003] and Sandy [2012]). This region is also intensely developed with nearly 1.7 million residents within the greater Hampton Roads metropolitan area. Anthropogenic changes to land cover in the lower bay can directly impact basin drainage and storm surge propagation with impacts reaching beyond the immediate coastal zone to affect flooding in inland areas. While construction of seawall barriers around population centers may provide storm surge protection to a specifically defined area, these barriers deflect storm surge rather than attenuate it, underscoring the importance of wetlands. To analyze these impacts a framework was developed combining numerical simulations with a detailed hydrodynamic characterization of flow through coastal wetland areas. Storm surges were calculated using a hydrodynamic model (ADCIRC) coupled to a wave model (SWAN) forced by an asymmetric hurricane vortex model using the FEMA region 3 unstructured mesh (2.3 million nodes) under a High Performance Computing (HPC) environment. Multiple model simulations were performed using historical hurricanes data and hypothetical storms to compare the predicted storm surge inundation with various levels of wetland reduction and/or beach hardening. These data were combined and overlaid

  16. Earth Observation in aid of surge monitoring and forecasting: ESA's eSurge Project

    Science.gov (United States)

    Harwood, Phillip; Cipollini, Paolo; Snaith, Helen; Høyer, Jacob; Dwyer, Ned; Dunne, Declan; Stoffelen, Ad; Donlon, Craig

    2013-04-01

    The understanding and realistic modelling of surges supports both preparation and mitigation activities and should eventually bring enormous societal benefits, especially to some of the world's poorest countries. Earth Observation data from satellites have an important role to play in storm surge monitoring and forecasting, but the full uptake of these data by the users (such as environmental agencies and tidal prediction centres) must be first encouraged by showcasing their usefulness, and then supported by providing easy access. The European Space Agency has recognized the above needs and, through its Data User Element (DUE) programme, has initiated in 2011 the eSurge project, whose aims are: a) to contribute through Earth Observation to an integrated approach to storm surge, wave, sea-level and flood forecasting as part of a wider optimal strategy for building an improved forecast and warning capability for coastal inundation; and b) to increase the use of the advanced capabilities of ESA and other satellite data for storm surge applications. The project is led by Logica UK, with NOC (UK), DMI (Denmark), CMRC (Ireland) and KNMI (Netherlands) as scientific partners. eSurge aims to provide easy access to a wide range of relevant data for a range of historical surge events, as well as performing a series of experiments to demonstrate the value of this data, and running workshops and training courses to help users make use of the available data. The eSurge database of Earth Observation and in situ measurements for past surge events is now publicly available. In 2013 the project moves into its service demonstration phase, adding more data and events, including a demonstration near real time service. The project works closely with its users in order to meet their needs and to maximise the return of this data. A novel dataset provided by eSurge is coastal altimetry. Coastal altimetry has a prominent role to play as it measures directly the total water level envelope

  17. The use of coastal altimetry to support storm surge studies in project eSurge

    Science.gov (United States)

    Cipollini, P.; Harwood, P.; Snaith, H.; Vignudelli, S.; West, L.; Zecchetto, S.; Donlon, C.

    2012-04-01

    One of the most promising applications of the new field of coastal altimetry, i.e. the discipline aiming to recover meaningful estimates of geophysical parameters (sea level, significant wave height and wind speed) from satellite altimeter data in the coastal zone, is the study of storm surges. The understanding and realistic modelling of surges supports both preparation and mitigation activities and should eventually bring enormous societal benefits, especially to some of the world's poorest countries (like Bangladesh). Earth Observation data have an important role to play in storm surge monitoring and forecasting, but the full uptake of these data by users (such as environmental agencies and tidal prediction centres) must first be encouraged by showcasing their usefulness, and then supported by providing easy access. Having recognized the above needs, The European Space Agency has recently launched a Data User Element (DUE) project called eSurge. The main purposes of eSurge are a) to contribute to an integrated approach to storm surge, wave, sea-level and flood forecasting through Earth Observation, as part of a wider optimal strategy for building an improved forecast and early warning capability for coastal inundation; and b) to increase the use of the advanced capabilities of ESA and other satellite data for storm surge applications. The project is led by Logica UK, with NOC (UK), DMI (Denmark), CMRC (Ireland) and KNMI (Netherlands) as scientific partners. A very important component of eSurge is the development, validation and provision of dedicated coastal altimetry products, which is the focus of the present contribution. Coastal altimetry has a prominent role to play as it measures the total water level envelope directly, and this is one of the key quantities required by storm surge applications and services. But it can also provide important information on the wave field in the coastal strip, which helps the development of more realistic wave models that in

  18. Guiding Surge Reduction Strategies via Characterization of Coastal Surge Propagation and Internal Surge Generation within a Complex Bay/Estuary System, Galveston Bay, TX

    Science.gov (United States)

    Bass, B.; Torres, J.; Irza, N.; Bedient, P. B.; Dawson, C.; Proft, J.

    2015-12-01

    In this study, Hurricane Ike (2008) and a suite of synthetic storms are simulated in order to evaluate how different hurricane landfalls, wind intensities, and radius to maximum winds influence the surge response in complex semi-enclosed bays such as Galveston Bay, located along the Texas Gulf Coast. The Advanced CIRCulation and Simulating Waves Nearshore (ADCIRC+SWAN) models are employed to quantify surge in terms of its relative coastal contributions that propagate across barrier islands and tidal inlets and subsequently into Galveston Bay, the surge generated locally within the Bay itself, and the interaction between these coastal and local components of surge. Results from this research will further the current understanding of surge interactions in bay systems and guide coastal engineering surge reduction projects that need to consider multiple lines of defense to protect complex bay/estuary systems such as Galveston Bay, TX.

  19. Nonlinear chaotic model for predicting storm surges

    Directory of Open Access Journals (Sweden)

    M. Siek

    2010-09-01

    Full Text Available This paper addresses the use of the methods of nonlinear dynamics and chaos theory for building a predictive chaotic model from time series. The chaotic model predictions are made by the adaptive local models based on the dynamical neighbors found in the reconstructed phase space of the observables. We implemented the univariate and multivariate chaotic models with direct and multi-steps prediction techniques and optimized these models using an exhaustive search method. The built models were tested for predicting storm surge dynamics for different stormy conditions in the North Sea, and are compared to neural network models. The results show that the chaotic models can generally provide reliable and accurate short-term storm surge predictions.

  20. Hypergravity induced prolactin surge in female rats

    Science.gov (United States)

    Megory, E.; Oyama, J.

    1985-01-01

    Acute initial exposure to hypergravity (HG) was previously found to induce prolonged diestrous in rats, which was followed by return to normal estrous cycling upon more prolonged exposure to continuous HG. Bromergocryptine was found to prevent this prolonged diestrous. In this study it is found that in female rats 20 h of 3.14 G exposure (D-1 1200 h until D-2 0800 h) can induce prolactin surge at D-2 1600 h. Shorter exposure time (8 h), or exposure during a different part of the estrous cycle (19 h: from D-1 0700 h until D-2 0200 h) could not elicit this prolactin surge. Similar exposure of male rats of HG did not alter significantly their prolactin levels. It is possible that the hypothalamus of male and female rats responds differently to stimulation by HG.

  1. The Preliminary discussion on the software optimization model of field parameters under furrow irrigation in inland arid region%内陆干旱区沟灌田面参数的软件优化模型初探

    Institute of Scientific and Technical Information of China (English)

    雷呈刚

    2015-01-01

    影响内陆干旱地区沟灌灌水质量的田间因素主要为沟长、 入沟流量以及田面坡度, 本文主要通过Win-SRFR模型对影响沟灌灌水质量的各因素之间正交组合条件下的田间灌溉水有效利用率、 各点入渗水量、 灌水均匀度等评价指标进行模拟, 根据模拟的结果对沟长、 入沟流量以及田面坡度等因素进行优化组合, 提出适合该区域适宜的沟灌灌溉管理方式与影响灌水质量的各因素最佳组合, 模拟表明该地区适宜的沟长为60―80m,当田面坡度控制在1/500以下时, 小于1.0L/s的入沟流量时灌水质量较好, 田面坡度控制在1/1 000 以下时,大于1.0L/s的入沟流量时灌水质量更佳, 通过建立优化组合模型, 通过遗传算法得到该地区适宜的沟灌入沟流量和灌水时间为1.5L/s和38min.%The field factors of influencing the furrow irrigation quality in Hexi inland arid region were irrigation ditch length,flow and slope of field.This paper introduces the imitation of the evaluation of indexes such as the field irrigation water utilization efficiency ,amount of infiltrating water in every spots and the uniformity of irrigation water application ,by means of the WinSRFR model under orthogonal combination.Meanwhile ,based on the imitation results,it optimizes the field factors of furrow irrigation quality and come up with the best combination of these factors to adapt the furrow irrigation management in Hexi area.The results indicated that the appropriate ditch length was 60-80m ,the furrow irrigation quality was good under the field slope was be-ing controlled below 1/500 and the flow was being controlled less than 1.0L/s.The furrow irrigation quality was better under the field slope was being controlled below 1/1000 and the flow was being controlled greater than 1.0L/s.By means of setting up the optimization of combination model and genetic algorithm ,the appropriate flow (1.5L/s) and irrigation time (38min

  2. Liftoff of the 18 May 1980 surge of Mount St. Helens (USA) and the deposits left behind

    Science.gov (United States)

    Gardner, James E.; Andrews, Benjamin J.; Dennen, Robert

    2017-01-01

    The distance that ground-hugging pyroclastic density currents travel is limited partly by when they reverse buoyancy and liftoff into the atmosphere. It is not clear, however, what deposits are left behind by lofting flows. One current that was seen to liftoff was the surge erupted from Mount St. Helens on the morning of 18 May 1980. Before lofting, it had leveled a large area of thick forest (the blowdown zone). The outer edge of the devastated area—where trees were scorched but left standing (the scorched zone)—is where the surge is thought to have lifted off. Deposits in the outer parts of the blowdown and in the scorched zone were examined at 32 sites. The important finding is that the laterally moving surge traveled through the scorched zone, and hence, the change in tree damage does not mark the runout distance of the surge. Buoyancy reversal and liftoff are thus not preserved in the deposits where the surge lofted upwards. We propose, based on interpretation of eyewitness accounts and the impacts of the surge on trees and vehicles, that the surge consisted of a faster, dilute "overcurrent" and a slower "undercurrent," where most of the mass (and heat) was retained. Reasonable estimates for flow density and velocity show that dynamic pressure of the surge (i.e., its ability to topple trees) peaked near the base of the overcurrent. We propose that where the overcurrent began to liftoff, the height of peak dynamic pressure rose above the trees and stopped toppling them. The slower undercurrent continued forward, however, scorching trees, but lacked the dynamic pressure needed to topple them. Grain-size variations argue that it slowed from ˜30 m s-1 when it entered the scorched zone to ˜3 m s-1 at the far end.

  3. Runout distance and dynamic pressure of pyroclastic density currents: Evidence from 18 May 1980 blast surge of Mount St. Helens

    Science.gov (United States)

    Gardner, J. E.; Andrews, B. J.

    2016-12-01

    Pyroclastic density currents (flows and surges) are one of the most deadly hazards associated with volcanic eruptions. Understanding what controls how far such currents will travel, and how their dynamic pressure evolves, could help mitigate their hazards. The distance a ground hugging, pyroclastic density current travels is partly limited by when it reverses buoyancy and lifts off into the atmosphere. The 1980 blast surge of Mount St. Helens offers an example of a current seen to lift off. Before lofting, it had traveled up to 20 km and leveled more than 600 km3 of thick forest (the blowdown zone). The outer edge of the devastated area - where burned trees that were left standing (the singe zone) - is where the surge is thought to have lifted off. We recently examined deposits in the outer parts of the blowdown and in the singe zone at 32 sites. The important finding is that the laterally moving surge travelled into the singe zone, and hence the change in tree damage does not mark the run out distance of the ground hugging surge. Eyewitness accounts and impacts on trees and vehicles reveal that the surge consisted of a fast, dilute "overcurrent" and a slower "undercurrent", where most of the mass (and heat) was retained. Reasonable estimates for flow density and velocity show that dynamic pressure of the surge (i.e., its ability to topple trees) peaked near the base of the overcurrent. We propose that when the overcurrent began to lift off, the height of peak dynamic pressure rose above the trees and stopped toppling them. The slower undercurrent continued forward, burning trees but it lacked the dynamic pressure needed to topple them. Grain-size variations argue that it slowed from 30 m/s when it entered the singe zone to 3 m/s at the far end. Buoyancy reversal and liftoff are thus not preserved in the deposits where the surge lofted upwards.

  4. Probabilistic Storm Surge Hazard Assessment in Martinique

    Science.gov (United States)

    Krien, Yann; Dudon, Bernard; Sansorgne, Eliot; Roger, Jean; Zahibo, Narcisse; Roquelaure, Stevie

    2013-04-01

    Located at the center of the Lesser Antilles, Martinique is under the threat of hurricanes formed over the warm tropical waters of the Atlantic Ocean and Caribbean Sea. These events can be extremely costly in terms of human, property, and economic losses. Storm surge hazard studies are hence required to provide guidance to emergency managers and decision-makers. A few studies have been conducted so far in the French Lesser Antilles, but they mainly rely on scarce historical data of extreme sea levels or numerical models with coarse resolutions. Recent progress in statistical techniques for generating large number of synthetic hurricanes as well as availability of high-resolution topographic and bathymetric data (LIDAR) and improved numerical models enables us today to conduct storm surge hazard assessment studies with much more accuracy. Here we present a methodology to assess cyclonic surge hazard in Martinique both at regional and local scales. We first simulate the storm surges that would be induced by a large set of potential events generated by the statistical/deterministic models of Emanuel et al. [2006]. We use the ADCIRC-SWAN coupled models (Dietrich et al 2012) to simulate inundation inland with grid resolutions of up to 50-100m in the coastal area for the whole island.These models are validated against observations during past events such as hurricane Dean in 2007. The outputs can then be used in some specific sites to force higher resolution models for crisis management and local risk assessment studies. This work is supported by the INTERREG IV « Caribbean » program TSUNAHOULE.

  5. A new concept for glacial geological investigations of surges, based on High-Arctic examples (Svalbard)

    Science.gov (United States)

    Lønne, Ida

    2016-01-01

    Svalbard is a key area for the investigation of glacial surges, and almost two centuries worth of field observations exists from this region. Studies have shown that the course of a surge and the associated formation of landforms are strongly influenced by basinal factors, and that the broad range of variables involved can hamper interpretations and comparisons. Based on a review of surges in Svalbard, a new concept for glacial geological investigations has been developed that combines ice-flows, ice-front movements, and morphostratigraphy. The concept is comprised of the following four elements: 1) classification based on the configuration and characteristics of the receiving basin, 2) division of the surge cycle into six stages, 3) guidelines for morphological mapping, and 4) use of an allostratigraphic approach for interpreting ice-front movements. In this context, delineation of the active phase is critical, which include the history of terminus movements, and four main categories of receiving basins are recognized. These are (A) terrestrial basins with deformable substrates, (B) terrestrial basins with poorly deformable substrates, (C) shallow water basins, and (D) deep water basins. The ice-front movement history is reconstructed by coupling information from the proglacial moraines (syn-surge), the supraglacial moraines (post-surge), and the associated traces of meltwater to the surge stages (I-VI). This approach has revealed a critical relationship between the termination of the active phase and three morphological elements, namely, the maximum ice-front position, the maximum moraine extent and the youngest proglacial moraine, which are unique for each of the basins A-D. The concept is thus a novel and more precise approach for mapping the active phase and the active phase duration, as shown by the ∼12-year long surge of Fridtjovbreen, where stage I was 30 months (inception), stage II was 54 months (ice-front advance), stage III was 12 months (stillstand

  6. Design and Characterization of a Centrifugal Compressor Surge Test Rig

    Directory of Open Access Journals (Sweden)

    Kin Tien Lim

    2011-01-01

    Full Text Available A detailed description of a new centrifugal compressor surge test rig is presented. The objective of the design and development of the rig is to study the surge phenomenon in centrifugal compression systems and to investigate a novel method of surge control by active magnetic bearing servo actuation of the impeller axial tip clearance. In this paper, we focus on the design, initial setup, and testing of the rig. The latter two include the commissioning of the rig and the experimental characterization of the compressor performance. The behavior of the compressor during surge is analyzed by driving the experimental setup into surge. Two fundamental frequencies, 21 Hz and 7 Hz, connected to the surge oscillation in the test rig are identified, and the observed instability is categorized according to the intensity of pressure fluctuations. Based on the test results, the excited pressure waves are clearly the result of surge and not stall. Also, they exhibit the characteristics of mild and classic surge instead of deep surge. Finally, the change in the compressor performance due to variation in the impeller tip clearance is experimentally examined, and the results support the potential of the tip clearance modulation for the control of compressor surge. This is the first such demonstration of the feasibility of surge control of a compressor using active magnetic bearings.

  7. Surge investigations in a radial single-stage blower with adjustable inlet guide vanes

    Energy Technology Data Exchange (ETDEWEB)

    Kryllowicz, W.; Horodko, L.; Hanausek, P.

    1996-12-31

    Experimental investigations of the influence of adjustable inlet guide vanes on the surge propagation in a radial single-stage blower system were carried out. The object of the investigations was a blower with a semi-open impeller with radially ended blades and a vaneless diffuser. The blower maximum pressure rate was {Pi} = 1.52 at the mass flow equal to m = 13.8 kg/s. The test instrumentation used consisted of classic probes and thermocouples and fast response semi-conductor pressure transducers located in flow path walls. Additionally, the noise level for different blower operating points was measured. These investigations made it possible to identify the mild and deep surge regions, the region of an inlet recirculation phenomenon as well as an inlet reverse flow phenomenon in the function of the IGV adjustment angle. (orig.)

  8. Basal processes beneath an Arctic glacier and their geomorphic imprint after a surge, Elisebreen, Svalbard

    Science.gov (United States)

    Christoffersen, Poul; Piotrowski, Jan A.; Larsen, Nicolaj K.

    2005-09-01

    The foreground of Elisebreen, a retreating valley glacier in West Svalbard, exhibits a well-preserved assemblage of subglacial landforms including ice-flow parallel ridges (flutings), ice-flow oblique ridges (crevasse-fill features), and meandering ridges (infill of basal meltwater conduits). Other landforms are thrust-block moraine, hummocky terrain, and drumlinoid hills. We argue in agreement with geomorphological models that this landform assemblage was generated by ice-flow instability, possibly a surge, which took place in the past when the ice was thicker and the bed warmer. The surge likely occurred due to elevated pore-water pressure in a thin layer of thawed and water-saturated till that separated glacier ice from a frozen substratum. Termination may have been caused by a combination of water drainage and loss of lubricating sediment. Sedimentological investigations indicate that key landforms may be formed by weak till oozing into basal cavities and crevasses, opening in response to accelerated ice flow, and into water conduits abandoned during rearrangement of the basal water system. Today, Elisebreen may no longer have surge potential due to its diminished size. The ability to identify ice-flow instability from geomorphological criteria is important in deglaciated terrain as well as in regions where ice dynamics are adapting to climate change.

  9. Friction distribution at the base of a surging glacier inferred from an inverse method

    Science.gov (United States)

    Gagliardini, O.; Jay-Allemand, M.; Gillet-Chaulet, F.

    2010-12-01

    The main objectives of this study is to investigate the basal conditions of a surging glacier. For that, we apply the inverse method proposed by Arthern and Gudmundsson (Journal of Glaciology, 2010). This method is based on an iterative descent algorithm numerically implemented in the finite element code Elmer/Ice. Neumann and Dirichlet problems are solved successively in order to minimize the cost function constructed as the norm of the difference between the basal velocities solutions of both problems. The method is applied to the Variegated glacier, a surge type glacier located in Alaska. We use measurements on this glacier carried out by Raymond and Harrison (Journal of Glaciology, 1988) during the quiescent stage of 1966-81 and the surge of 1982-83. Data contain surface velocities as well as the bed and surface topography along the central flow-line. In a first step, for each set of data obtained at different dates, we run the model diagnostically to solve for the basal drag coefficient in order to match the modelled horizontal surface velocities and the observed velocities. In a second step, inferred basal drag coefficient are analysed and then integrated in a transient simulation which cover the whole period of the data set, i.e. both quiescent and surge stages. Results show the contribution of basal sliding in the surge phenomenon and the modification of the basal condition from the quiescent to the surge stages. These modifications can be interpreted in term of changes in sub-glacial water pressure and runoff.

  10. Effect of plastic tarps over raised-beds and potassium thiosulfate in furrows on chloropicrin emissions from drip fumigated fields.

    Science.gov (United States)

    Qin, Ruijun; Gao, Suduan; McDonald, Jason A; Ajwa, Husein; Shem-Tov, Shachar; Sullivan, David A

    2008-06-01

    Plastic tarps are commonly used in raised bed strawberry production to minimize emissions of preplant soil fumigants and are left in place throughout the growing season as part of the standard cultural practices. Soil amendments with chemicals such as thiosulfate (S2O3(2-)) can reduce fumigant emissions. A field study was conducted near Santa Maria, CA to determine the effects of low density polyethylene (LDPE) and virtually impermeable film (VIF) over raised-beds and applying potassium thiosulfate (KTS) in furrows on reducing chloropicrin (CP) emissions from a strawberry field. Four fields (or treatments) were tested with 224 kg ha(-1) CP drip-applied threecm under the soil surface. The CP flux from bed tops and furrows and gas-phase concentrations under the tarps were monitored for five d. The CP emission flux and concentration under tarp were highest immediately following application. Diurnal temperature change affected CP concentration and emission fluxes (higher values during the day and lower at night). Slightly higher CP cumulative emission occurred using LDPE tarp (19%) compared to VIF (17%). Normalized flux (CP emission flux from the beds divided by CP concentration under the tarp) being estimated from field measurement was slightly higher for LDPE than VIF indicating different tarp permeability in the field. Because of extremely low emissions from the furrows (emission loss), KTS application to furrow treatments did not show further emission reductions than non-KTS treatments. This indicates that emission reduction should focus on the tarp above raised-beds when fumigant was drip-applied near bed-surface.

  11. The cranial anatomy of Discosauricsus Kuhn, a seymouriamorph tetrapod from the Lower Permian of the Boskovice Furrow (Czech Republic)

    OpenAIRE

    Klembara, J.

    1997-01-01

    A detailed description is given of the cranial anatomy of the Lower Permian tetrapod Discosauriscus. This material is three-dimensionally preserved and represents one of the best know seymouriamorph tetrapods. Two species, D. austriacus and D. pulcherrimus, are distinguished in the material from the Boskovice Furrow. D. austriacus is abundant, D. pulcherrimus is rare. The two species differ in the following features: (1) the shape of the postorbital and the jugal and the nature of their junct...

  12. Climatic Controls on the Distribution of Surging Glaciers

    Science.gov (United States)

    Sevestre, H.; Benn, D.

    2012-12-01

    Surge-type glaciers are scattered in a non-random fashion, gathered in clusters in some glaciated regions. One group of clusters forms an Arctic and Sub-Arctic 'crescent', spanning from Alaska-Yukon, through Arctic Canada, West and East Greenland, Iceland, Svalbard and Novaya Zemlya. Another cluster occurs in western High Asia, including the Karakoram Mountains. Although several studies have assessed the influence of environmental controls on surging, so far none has provided a satisfactory explanation for the geographical location of these clusters. The distribution of such glaciers undoubtedly holds the keys of a better understanding on the controls on surging behaviour. For this study, two glacier populations are considered. First, a global inventory of glacier surges has been compiled, based on published observations, field reports and remote sensing studies. This digital database is structured in three tables, respectively providing information on the location and geometry of each surge-type glacier, surge dates and magnitude, and methodology employed at the time of observation. This global dataset is compared to the population of "non-surge-type glaciers" based on the Randolph Glacier Inventory version 2.0 excluding the inventoried surging glaciers. In both populations, glaciers are classified depending on their geometry and thermal regime. Downscaled climatic datasets are used to identify climatic envelopes associated with clusters of surging glaciers. We identified which environments are most prone to be associated to glacier surging, and examined the influence of these parameters on the surge cycle duration and character. These results emphasize the importance of external controls on surging (as against individual surges), and promote the need to study this behaviour in the frame of an energy-balance budget.

  13. Banded applications are highly effective in minimising herbicide migration from furrow-irrigated sugar cane.

    Science.gov (United States)

    Oliver, Danielle P; Anderson, Jenny S; Davis, Aaron; Lewis, Stephen; Brodie, Jon; Kookana, Rai

    2014-01-01

    Runoff from farm fields is a common source of herbicide residues in surface waters in many agricultural industries around the world. In Queensland, Australia, the runoff of PSII inhibitor herbicides (in particular diuron and atrazine) is a major concern due to their potential impact on the Great Barrier Reef. This study compared the conventional practice of broadcast application of herbicides in sugarcane production across the whole field with the banded application of particular herbicides onto raised beds only using a shielded sprayer. This study found that the application of two moderately soluble herbicides, diuron and atrazine, to only the raised beds decreased the average total load of both herbicides moving off-site by >90% compared with the conventional treatment. This was despite the area being covered with the herbicides by the banded application being only 60% less than with the conventional treatment. The average total amount of atrazine in drainage water was 7.5% of the active ingredient applied in the conventional treatment compared with 1.8% of the active ingredient applied in the banded application treatment. Similarly, the average total amount of diuron in drainage water was 4.6% of that applied in the conventional treatment compared with 0.9% of that applied in the banded application treatment. This study demonstrates that the application of diuron and atrazine to raised beds only is a highly effective way of minimising migration of these herbicides in drainage water from furrow irrigated sugarcane.

  14. Evaluation of the Effect of Split application of Urea on Nitrogen Losses in Furrow Fertigation

    Directory of Open Access Journals (Sweden)

    farid feizolahpour

    2017-01-01

    Full Text Available Introduction: Broadcast fertilization method increases fertilizer losses while results in lower nutrient absorption by plant roots. Fertigation is an effective method to increase water and fertilizer efficiency and to reduce the losses of nitrogen. Moreover, it allows farmers to apply the nutrients in splits and few amounts in response to crop needs. In the present study, a field experiment was conducted to investigate the effects of split application of fertilizer in furrow fertigation on nitrogen losses and corn yield. Materials and Methods: Field experiments were carried out factorially in a randomized complete block design with four replicates. Experimental treatments were consisted of three fertilizer splits (two, three, and four splits and three levels of urea fertilizer (60, 80 and 100% of required urea fertilizer, which compared with the common method (broadcasting fertilizer as used by farmers in the fields. Experiments were conducted on a one hectare field in 120 meter long and open end furrows. During the crop season, Irrigation water was applied in the same way for all fertigation treatments and the third type of the WSC flumes was used to measure the amount of input and output water in irrigation events. Moreover, for determining the indexes of uniformity of water distribution in carrying out fertigation experiments, the amount of infiltration into the soil was calculated using the Kostiakov-Louis equation. The parameters of this equation were determined using the water volume balance method. Injection of Urea fertilizer was done by using 40-liter barrels were placed at the beginning of Furrows. In this study, the injection of fertilizers was applied in the last 10 to 20 minutes of irrigation time. Results and Discussions: Results showed that water distribution uniformities of low quarter and low half in all tests were very high. Such that the water low quarter distribution uniformities for all treatments were between 90.5 to 98

  15. Atlantic hurricane surge response to geoengineering

    Energy Technology Data Exchange (ETDEWEB)

    Moore, John C.; Grinsted, Aslak; Guo, Xiaoran; Yu, Xiaoyong; Jevrejeva, Svetlana; Rinke, Annette; Cui, Xuefeng; Kravitz, Ben; Lenton, Andrew; Watanabe, Shingo; Ji, Duoying

    2015-10-26

    Devastating Atlantic hurricanes are relatively rare events. However their intensity and frequency in a warming world may rapidly increase by a factor of 2-7 for each degree of increase in mean global temperature. Geoengineering by stratospheric sulphate aerosol injection cools the tropics relative to the polar regions, including the hurricane main development region in the Atlantic, suggesting that geoengineering may be an effective method of controlling hurricanes. We examine this hypothesis using 8 Earth System Model simulations of climate under the GeoMIP G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the RCP4.5 scenario. Global mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those in RCP4.5, but sulphate injection would have to double between 2020 and 2070 to balance RCP 4.5 to nearly 10 Tg SO2 yr-1, with consequent implications for damage to stratospheric ozone. We project changes in storm frequencies using a temperature-dependent Generalized Extreme Value statistical model calibrated by historical storm surges from 1923 and observed temperatures. The numbers of storm surge events as big as the one that caused the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this is only marginally statistically significant. However, when sea level rise differences at 2070 between RCP4.5 and geoengineering are factored in to coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5 year events and perhaps halved for 50 year surges.

  16. Atlantic hurricane surge response to geoengineering.

    Science.gov (United States)

    Moore, John C; Grinsted, Aslak; Guo, Xiaoran; Yu, Xiaoyong; Jevrejeva, Svetlana; Rinke, Annette; Cui, Xuefeng; Kravitz, Ben; Lenton, Andrew; Watanabe, Shingo; Ji, Duoying

    2015-11-10

    Devastating floods due to Atlantic hurricanes are relatively rare events. However, the frequency of the most intense storms is likely to increase with rises in sea surface temperatures. Geoengineering by stratospheric sulfate aerosol injection cools the tropics relative to the polar regions, including the hurricane Main Development Region in the Atlantic, suggesting that geoengineering may mitigate hurricanes. We examine this hypothesis using eight earth system model simulations of climate under the Geoengineering Model Intercomparison Project (GeoMIP) G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the Representative Concentration Pathway (RCP) 4.5 scenario. Global mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those temperature increases in the RCP4.5. However, sulfate injection would have to double (to nearly 10 teragrams of SO2 per year) between 2020 and 2070 to balance the RCP4.5, approximately the equivalent of a 1991 Pinatubo eruption every 2 y, with consequent implications for stratospheric ozone. We project changes in storm frequencies using a temperature-dependent generalized extreme value statistical model calibrated by historical storm surges and observed temperatures since 1923. The number of storm surge events as big as the one caused by the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this reduction is only marginally statistically significant. Nevertheless, when sea level rise differences in 2070 between the RCP4.5 and geoengineering are factored into coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5-y events and about halved for 50-y surges.

  17. Glacier surge after ice shelf collapse.

    Science.gov (United States)

    De Angelis, Hernán; Skvarca, Pedro

    2003-03-07

    The possibility that the West Antarctic Ice Sheet will collapse as a consequence of ice shelf disintegration has been debated for many years. This matter is of concern because such an event would imply a sudden increase in sea level. Evidence is presented here showing drastic dynamic perturbations on former tributary glaciers that fed sections of the Larsen Ice Shelf on the Antarctic Peninsula before its collapse in 1995. Satellite images and airborne surveys allowed unambiguous identification of active surging phases of Boydell, Sjögren, Edgeworth, Bombardier, and Drygalski glaciers. This discovery calls for a reconsideration of former hypotheses about the stabilizing role of ice shelves.

  18. Electrothermal model for complete metal-oxide surge arresters

    Energy Technology Data Exchange (ETDEWEB)

    Costa, E. Guedes da; Naidu, S.R. [UFPB, Dept. of Electrical Engineering, Campina Grande, PB (Brazil); Lima, A. Guedes de [CEFET-PB, Dept. of Mechanical Engineering, Joao Pessoa, PB (Brazil)

    2001-01-01

    A computational, electrothermal model for a complete metal-oxide surge arrester based on the implicit form of the finite-differences method is presented. The model is used to calculate the cooling curve after the application of overvoltages and the temperature variations during standard test. The model has been checked against experiments carried out on a test section and a complete surge arrester and the behaviour of a hypothetical surge arrester during standard tests simulated. (Author)

  19. Design and Characterization of a Centrifugal Compressor Surge Test Rig

    OpenAIRE

    2011-01-01

    A detailed description of a new centrifugal compressor surge test rig is presented. The objective of the design and development of the rig is to study the surge phenomenon in centrifugal compression systems and to investigate a novel method of surge control by active magnetic bearing servo actuation of the impeller axial tip clearance. In this paper, we focus on the design, initial setup, and testing of the rig. The latter two include the commissioning of the rig and the experimental characte...

  20. Investigating changes in basal conditions of Variegated Glacier prior to and during its 1982–1983 surge

    Directory of Open Access Journals (Sweden)

    M. Jay-Allemand

    2011-08-01

    Full Text Available Variegated Glacier (Alaska is known to surge periodically after a sufficient amount of cumulative mass balance is reached, but this observation is difficult to link with changes in the basal conditions. Here, using a 10-yr dataset, consisting of surface topography and surface velocity observations along a flow line for 25 dates, we have reconstructed the evolution of the basal conditions prior to and during the 1982–1983 surge. The model solves the full-Stokes problem along the central flow line using the finite element method. For the 25 dates of the dataset, the basal friction parameter distribution is inferred using the inverse method proposed by Arthern and Gudmundsson (2010. This method is here slightly modified by incorporating a regularisation term in the cost function to avoid short wavelength changes in the friction parameter. Our results indicate that dramatic changes in the basal conditions occurred between 1973 to 1983. Prior to the surge, periodic changes can be observed between winter and summer, with a regular increase of the sliding from 1973 to 1982. During the surge, the basal friction decreased dramatically and an area of very low friction moved from the upper part of the glacier to its terminus. Using a more complex friction law, these changes in basal sliding are then interpreted in terms of basal water pressure. Our results support that dramatic changes took place in the subglacial drainage system of Variegated Glacier, moving from a relatively efficient drainage system prior to the surge to an inefficient one during the surge. By reconstructing the water pressure evolution at the base of the glacier it is possible to propose a scenario for the hydrological history leading to the occurrence of a surge.

  1. Performance Comparison of the European Storm Surge Models and Chaotic Model in Forecasting Extreme Storm Surges

    Science.gov (United States)

    Siek, M. B.; Solomatine, D. P.

    2009-04-01

    Storm surge modeling has rapidly developed considerably over the past 30 years. A number of significant advances on operational storm surge models have been implemented and tested, consisting of: refining computational grids, calibrating the model, using a better numerical scheme (i.e. more realistic model physics for air-sea interaction), implementing data assimilation and ensemble model forecasts. This paper addresses the performance comparison between the existing European storm surge models and the recently developed methods of nonlinear dynamics and chaos theory in forecasting storm surge dynamics. The chaotic model is built using adaptive local models based on the dynamical neighbours in the reconstructed phase space of observed time series data. The comparison focused on the model accuracy in forecasting a recently extreme storm surge in the North Sea on November 9th, 2007 that hit the coastlines of several European countries. The combination of a high tide, north-westerly winds exceeding 50 mph and low pressure produced an exceptional storm tide. The tidal level was exceeded 3 meters above normal sea levels. Flood warnings were issued for the east coast of Britain and the entire Dutch coast. The Maeslant barrier's two arc-shaped steel doors in the Europe's biggest port of Rotterdam was closed for the first time since its construction in 1997 due to this storm surge. In comparison to the chaotic model performance, the forecast data from several European physically-based storm surge models were provided from: BSH Germany, DMI Denmark, DNMI Norway, KNMI Netherlands and MUMM Belgium. The performance comparison was made over testing datasets for two periods/conditions: non-stormy period (1-Sep-2007 till 14-Oct-2007) and stormy period (15-Oct-2007 till 20-Nov-2007). A scalar chaotic model with optimized parameters was developed by utilizing an hourly training dataset of observations (11-Sep-2005 till 31-Aug-2007). The comparison results indicated the chaotic

  2. Simplified Storm Surge Simulations Using Bernstein Polynomials

    Science.gov (United States)

    Beisiegel, Nicole; Behrens, Jörn

    2016-04-01

    Storm surge simulations are vital for forecasting, hazard assessment and eventually improving our understanding of Earth system processes. Discontinuous Galerkin (DG) methods have recently been explored in that context, because they are locally mass-conservative and in combination with suitable robust nodal filtering techniques (slope limiters) positivity-preserving and well-balanced for the still water state at rest. These filters manipulate interpolation point values in every time step in order to retain the desirable properties of the scheme. In particular, DG methods are able to represent prognostic variables such as the fluid height at high-order accuracy inside each element (triangle). For simulations that include wetting and drying, however, the high-order accuracy will destabilize the numerical model because point values on quadrature points may become negative during the computation if they do not coincide with interpolation points. This is why the model that we are presenting utilizes Bernstein polynomials as basis functions to model the wetting and drying. This has the advantage that negative pointvalues away from interpolation points are prevented, the model is stabilized and no additional time step restriction is introduced. Numerical tests show that the model is capable of simulating simplified storm surges. Furthermore, a comparison of model results with third-order Bernstein polynomials with results using traditional nodal Lagrange polynomials reveals an improvement in numerical convergence.

  3. Hospital bioterrorism planning and burn surge.

    Science.gov (United States)

    Kearns, Randy D; Myers, Brent; Cairns, Charles B; Rich, Preston B; Hultman, C Scott; Charles, Anthony G; Jones, Samuel W; Schmits, Grace L; Skarote, Mary Beth; Holmes, James H; Cairns, Bruce A

    2014-01-01

    On the morning of June 9, 2009, an explosion occurred at a manufacturing plant in Garner, North Carolina. By the end of the day, 68 injured patients had been evaluated at the 3 Level I trauma centers and 3 community hospitals in the Raleigh/Durham metro area (3 people who were buried in the structural collapse died at the scene). Approximately 300 employees were present at the time of the explosion, when natural gas being vented during the repair of a hot water heater ignited. The concussion from the explosion led to structural failure in multiple locations and breached additional natural gas, electrical, and ammonia lines that ran overhead in the 1-story concrete industrial plant. Intent is the major difference between this type of accident and a terrorist using an incendiary device to terrorize a targeted population. But while this disaster lacked intent, the response, rescue, and outcomes were improved as a result of bioterrorism preparedness. This article discusses how bioterrorism hospital preparedness planning, with an all-hazards approach, became the basis for coordinated burn surge disaster preparedness. This real-world disaster challenged a variety of systems, hospitals, and healthcare providers to work efficiently and effectively to manage multiple survivors. Burn-injured patients served as a focus for this work. We describe the response, rescue, and resuscitation provided by first responders and first receivers as well as efforts made to develop burn care capabilities and surge capacity.

  4. Tide and skew surge independence: New insights for flood risk

    Science.gov (United States)

    Williams, Joanne; Horsburgh, Kevin J.; Williams, Jane A.; Proctor, Robert N. F.

    2016-06-01

    Storm surges are a significant hazard to coastal communities around the world, putting lives at risk and costing billions of dollars in damage. Understanding how storm surges and high tides interact is crucial for estimating extreme water levels so that we can protect coastal communities. We demonstrate that in a tidal regime the best measure of a storm surge is the skew surge, the difference between the observed and predicted high water within a tidal cycle. Based on tide gauge records spanning decades from the UK, U.S., Netherlands, and Ireland we show that the magnitude of high water exerts no influence on the size of the most extreme skew surges. This is the first systematic proof that any storm surge can occur on any tide, which is essential for understanding worst-case scenarios. The lack of surge generation dependency on water depth emphasizes the dominant natural variability of weather systems in an observation-based analysis. Weak seasonal relationships between skew surges and high waters were identified at a minority of locations where long-period changes to the tidal cycle interact with the storm season. Our results allow advances to be made in methods for estimating the joint probabilities of storm surges and tides.

  5. Auroral radio absorption and the westward travelling surge

    Energy Technology Data Exchange (ETDEWEB)

    Collis, P.N.; Korth, A.

    1983-11-01

    Measurements from a network of riometers during the passage of an auroral westward traveling surge are presented. These show that the energetic precipitation producing the radio absorption expands in an almost identical fashion to the softer precipitation associated with the visible surge; but it is delayed by about two minutes with respect to the surge. The delay is interpreted as a hardening of the precipitating electron spectrum as the surge goes by. Simultaneous observations of electrons at synchronous orbit are shown to support this conclusion. 24 references.

  6. Over 400 previously undocumented Svalbard surge-type glaciers identified

    Science.gov (United States)

    Farnsworth, Wesley R.; Ingólfsson, Ólafur; Retelle, Michael; Schomacker, Anders

    2016-07-01

    Identifying glaciers that exhibit surge-type behavior is important when using evidence of ice front fluctuations as a proxy for reconstructing past climate oscillations. This study identifies previously undocumented surge-type glaciers in Svalbard, based on the presence of crevasse squeeze ridges in glacier forelands. Crevasse squeeze ridges are landforms suggested to be unique to surging glacier land systems. Estimates vary greatly as to the actual percentage of surge-type glaciers in Svalbard, and consequently their distribution pattern is poorly understood. A detailed survey of recent (2008-2012), high-resolution aerial imagery from TopoSvalbard, provided by the Norwegian Polar Institute, allowed for a survey of all the glacier forelands in Svalbard. Before our study, 277 individual glaciers in Svalbard have been documented to exhibit surge behavior. By using crevasse squeeze ridges as indicators of surge behavior, we have identified 431 additional glaciers that have surged. We suggest that this is a modest value as the unique surge landforms were not visible in approximately one-third of the forelands with documented surge histories. Limits to the crevasse squeeze ridge technique are presented and potential controlling factors for crevasse squeeze ridge formation/preservation are discussed.

  7. On the magnitude and frequency of Karakoram Glacier surges

    Directory of Open Access Journals (Sweden)

    D. J. Quincey

    2013-10-01

    Full Text Available The return periods of Karakoram glacier surges are almost entirely unknown. Here, we present evidence of an historic surge of the Khurdopin Glacier that began in the mid-1970s and peaked in 1979. Measured surface displacements reached > 5 km yr–1, two orders of magnitude faster than during quiescence and twice as large as any previously recorded velocity in the region. The Khurdopin Glacier next surged in the late-1990s, equating to a return period of 20 yr. Surge activity in the region needs to be better understood if accurate mass balance assessments of Hindu-Kush–Karakoram–Himalaya glaciers are to be made.

  8. Orbit/CLASP is required for myosin accumulation at the cleavage furrow in Drosophila male meiosis.

    Directory of Open Access Journals (Sweden)

    Daishi Kitazawa

    Full Text Available Peripheral microtubules (MTs near the cell cortex are essential for the positioning and continuous constriction of the contractile ring (CR in cytokinesis. Time-lapse observations of Drosophila male meiosis showed that myosin II was first recruited along the cell cortex independent of MTs. Then, shortly after peripheral MTs made contact with the equatorial cortex, myosin II was concentrated there in a narrow band. After MT contact, anillin and F-actin abruptly appeared on the equatorial cortex, simultaneously with myosin accumulation. We found that the accumulation of myosin did not require centralspindlin, but was instead dependent on Orbit, a Drosophila ortholog of the MT plus-end tracking protein CLASP. This protein is required for stabilization of central spindle MTs, which are essential for cytokinesis. Orbit was also localized in a mid-zone of peripheral MTs, and was concentrated in a ring at the equatorial cortex during late anaphase. Fluorescence resonance energy transfer experiments indicated that Orbit is closely associated with F-actin in the CR. We also showed that the myosin heavy chain was in close proximity with Orbit in the cleavage furrow region. Centralspindlin was dispensable in Orbit ring formation. Instead, the Polo-KLP3A/Feo complex was required for the Orbit accumulation independently of the Orbit MT-binding domain. However, orbit mutations of consensus sites for the phosphorylation of Cdk1 or Polo did not influence the Orbit accumulation, suggesting an indirect regulatory role of these protein kinases in Orbit localization. Orbit was also necessary for the maintenance of the CR. Our data suggest that Orbit plays an essential role as a connector between MTs and the CR in Drosophila male meiosis.

  9. Storm surges formation in the White and Barents Seas

    Science.gov (United States)

    Arkhipkin, Victor; Dobrolyubov, Sergey; Korablina, Anastasia; Myslenkov, Stanislav

    2016-04-01

    Investigation of storm surges in the Arctic seas are of high priority in Russia due to the active development of offshore oil and gas, construction of facilities in the coastal zone, as well as for the safety of navigation. It is important to study the variability of surges, to predict this phenomena and subsequent economic losses, thus including such information into the Russian Arctic Development Program 2020. Surges in the White and Barents Seas are caused mainly by deep cyclones of two types: "diving" from the north (88% of all cyclones) and western. The average height of the storm surges in the White Sea is 0.6-0.9 m. An average duration of storm surges is about 80 hours. Mathematical modeling is used to analyze the characteristics of storm surges formation in the Dvina Bay of the White Sea, and in the Varandey village on the Barents Sea coast. Calculating storm surge heights in the White and Barents seas is performed using the ADCIRC model on an unstructured grid with a step from 20 km in the Barents Sea to 100 m in the White Sea. Unstructured grids allowed keeping small features of the coastline of the White and Barents seas, small islands and shallow banks, and assessing their impact on the development and transformation of wind-generated waves. The ADCIRC model used data of wind field reanalysis CFSv2. The storm surges were simulated for the time period from 1979 to 2010 and included scenarios with / without direct atmospheric pressure forcing, waves and tides. Numerical experiments have revealed distribution of storm surges in channels of the Northern Dvina River delta. The storm surges spreads in the model from the north-north-west of the Dvina Bay. As storm surge moves from the wellhead to the seaside estuary of the Northern Dvina (district Solombala), its height increases from 0.5 to 2 m. We also found a non-linear interaction of the surge and tide during the phase of surge destruction. This phenomenon is the highest in the period of low water, and the

  10. Surges Initiated by Newly-emerging Satellite Magnetic Fields

    Science.gov (United States)

    Wang, Jun-feng; Zhou, Tuan-hui; Ji, Hai-sheng

    2014-01-01

    On July 22, 2011 and in the active region NOAA 11259 there ap- peared the event of the ejection of solar atmospheric Hα surges. According to the full-disc Hα observations of the Big Bear Solar Observatory in United States, three consecutive surges at one and the same place in the north of the main spot of the active region were discovered. The trajectories of these three surges exhib- ited the figure of straight lines, and their integral configuration is like an inverted Eiffel Tower. The first two surges are quite similar, and in each of them there appeared two bright points in the northern part of the main spot. After several minutes, the surges appeared in the midst of bright points. When the bright- ness of the bright points attained the maximum value, the surges spouted out from the midst of bright points. And after reaching the maximum altitude, they quickly vanished. Before the ejection of the third surge took place, no bright points appeared. Besides, its maximal altitude is merely one half of that of the first two surges. Via a comparison with the SDO/HMI (Solar Dynamics Obser- vatory/Helioseismic and Magnetic Imager) data of radial magnetic fields, it is found that in more than one hour before the appearance of the first surge there emerged bipolar magnetic fields in the region of ejection. Besides, in several min- utes before the ejection of each Hα surge the magnetic fluxes of positive polarity diminished. Via our analysis it is found that there appeared reconnections be- tween the newly emerging satellite magnetic fields and the preexisting magnetic fields in the spot, and this caused the continuous ejections of Hα surges.

  11. Simulating storm surge inundation and damage potential within complex port facilities

    Science.gov (United States)

    Mawdsley, Robert; French, Jon; Fujiyama, Taku; Achutan, Kamalasudhan

    2017-04-01

    Storm surge inundation of port facilities can cause damage to critical elements of infrastructure, significantly disrupt port operations and cause downstream impacts on vital supply chains. A tidal surge in December 2013 in the North Sea partly flooded the Port of Immingham, which handles the largest volume of bulk cargo in the UK including major flows of coal and biomass for power generation. This flooding caused damage to port and rail transport infrastructure and disrupted operations for several weeks. This research aims to improve resilience to storm surges using hydrodynamic modelling coupled to an agent-based model of port operations. Using the December 2013 event to validate flood extent, depth and duration, we ran a high resolution hydrodynamic simulation using the open source Telemac 2D finite element code. The underlying Digital Elevation Model (DEM) was derived from Environment Agency LiDAR data, with ground truthing of the flood defences along the port frontage. Major infrastructure and buildings are explicitly resolved with varying degrees of permeability. Telemac2D simulations are run in parallel and take only minutes on a single 16 cpu compute node. Inundation characteristics predicted using Telemac 2D differ from a simple Geographical Information System 'bath-tub' analysis of the DEM based upon horizontal application of the maximum water level across the port topography. The hydrodynamic simulation predicts less extensive flooding and more closely matches observed flood extent. It also provides more precise depth and duration curves. Detailed spatial flood depth and duration maps were generated for a range of tide and surge scenarios coupled to mean sea-level rise projections. These inundation scenarios can then be integrated with critical asset databases and an agent-based model of port operation (MARS) that is capable of simulating storm surge disruption along wider supply chains. Port operators are able to act on information from a particular

  12. Will oscillating wave surge converters survive tsunamis?

    Directory of Open Access Journals (Sweden)

    L. O’Brien

    2015-07-01

    Full Text Available With an increasing emphasis on renewable energy resources, wave power technology is becoming one of the realistic solutions. However, the 2011 tsunami in Japan was a harsh reminder of the ferocity of the ocean. It is known that tsunamis are nearly undetectable in the open ocean but as the wave approaches the shore its energy is compressed, creating large destructive waves. The question posed here is whether an oscillating wave surge converter (OWSC could withstand the force of an incoming tsunami. Several tools are used to provide an answer: an analytical 3D model developed within the framework of linear theory, a numerical model based on the non-linear shallow water equations and empirical formulas. Numerical results show that run-up and draw-down can be amplified under some circumstances, leading to an OWSC lying on dry ground!

  13. A MICROGAP SURGE ABSORBER FABRICATED USING CONVENTIONAL SEMICONDUCTOR TECHNOLOGY

    Institute of Scientific and Technical Information of China (English)

    李宏; 阮航宇

    2001-01-01

    A new type microgap surge absorber fabricated by only semiconductor technique has in it a special structure silicon chip which forms microgaps for gas discharge with electrodes, and has advantages such as small size, low cost, suitability for mass production besides the desirable characteristics that common microgap surge absorbers have. Applications of this absorber in communication facilities are discussed.

  14. Scenario-based Storm Surge Vulnerability Assessment of Catanduanes

    Science.gov (United States)

    Suarez, J. K. B.

    2015-12-01

    After the devastating storm surge effect of Typhoon Haiyan, the public recognized an improved communication about risks, vulnerabilities and what is threatened by storm surge. This can be provided by vulnerability maps which allow better visual presentations and understanding of the risks and vulnerabilities. Local implementers can direct the resources needed for protection of these areas. Moreover, vulnerability and hazard maps are relevant in all phases of disaster management designed by the National Disaster Risk Reduction Council (NDRRMC) - disaster preparedness, prevention and mitigation and response and recovery and rehabilitation. This paper aims to analyze the vulnerability of Catanduanes, a coastal province in the Philippines, to storm surges in terms of four parameters: population, built environment, natural environment and agricultural production. The vulnerability study relies on the storm surge inundation maps based on the Department of Science and Technology Nationwide Operational Assessment of Hazards' (DOST-Project NOAH) proposed four Storm Surge Advisory (SSA) scenarios (1-2, 3, 4, and 5 meters) for predicting storm surge heights. To determine total percent affected for each parameter elements, an overlay analysis was performed in ArcGIS Desktop. Moreover, vulnerability and hazard maps are generated as a final output and a tool for visualizing the impacts of storm surge event at different surge heights. The result of this study would help the selected province to know their present condition and adapt strategies to strengthen areas where they are found to be most vulnerable in order to prepare better for the future.

  15. Predicting Storm Surges: Chaos, Computational Intelligence, Data Assimilation, Ensembles

    NARCIS (Netherlands)

    Siek, M.B.L.A.

    2011-01-01

    Accurate predictions of storm surge are of importance in many coastal areas. This book focuses on data-driven modelling using methods of nonlinear dynamics and chaos theory for predicting storm surges. A number of new enhancements are presented: phase space dimensionality reduction, incomplete time

  16. Switching Surge Analysis of Vacuum Circuit Breaker using EMTP

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ik Mo; Kim, Ji Hong [Hyundai Heavy Industry, Mechatronics Research Institute (Korea)

    2000-07-01

    The first objective of this study is to set up the switching surge analysis method in motor driving distribution system. The simplified model which can simulate the motor energization and circuit breaker re-ignitions, and each circuit element model is presented in this paper. The second objective is to calculate the quantity of surge over-voltage in real nuclear power station. And the surge suppressing measures are verified on the simulation basis. It is clarified that most cases are not satisfactory to meet the IEEE standard 522-1992 without using surge suppressing measures. In cases that the surge arrester are installed in distribution board at the load side of circuit breaker. The IEEE specification is fully met. (author). 6 refs., 4 figs., 3 tabs.

  17. Investigation of Surge Behavior in a Micro Centrifugal Compressor

    Institute of Scientific and Technical Information of China (English)

    Shimpei MIZUKI; Yuichiro ASAGA; Yushi ONO; Hoshio TSUJITA

    2006-01-01

    This paper reports the experimental and theoretical study of the surge occurred in prototyping an ultra micro centrifugal compressor. As the first step, the 10 times size model of an ultra micro centrifugal compressor having the 40 mm outer diameter was designed and manufactured. The detailed experimental investigations for the transient behavior of surge with several different values of B parameter were carried out. The experimental results during the surge were compared with those obtained by the non-linear lumped parameter theory in order to validate the effectiveness of the theoretical surge model for the micro centrifugal compressor. As a result, the quite different behavior of the surge appeared for the different values of B both in the experiment and in the analysis.

  18. Application of short-data methods on extreme surge levels

    Science.gov (United States)

    Feng, X.

    2014-12-01

    Tropical cyclone-induced storm surges are among the most destructive natural hazards that impact the United States. Unfortunately for academic research, the available time series for extreme surge analysis are very short. The limited data introduces uncertainty and affects the accuracy of statistical analyses of extreme surge levels. This study deals with techniques applicable to data sets less than 20 years, including simulation modelling and methods based on the parameters of the parent distribution. The verified water levels from water gauges spread along the Southwest and Southeast Florida Coast, as well as the Florida Keys, are used in this study. Methods to calculate extreme storm surges are described and reviewed, including 'classical' methods based on the generalized extreme value (GEV) distribution and the generalized Pareto distribution (GPD), and approaches designed specifically to deal with short data sets. Incorporating global-warming influence, the statistical analysis reveals enhanced extreme surge magnitudes and frequencies during warm years, while reduced levels of extreme surge activity are observed in the same study domain during cold years. Furthermore, a non-stationary GEV distribution is applied to predict the extreme surge levels with warming sea surface temperatures. The non-stationary GEV distribution indicates that with 1 Celsius degree warming in sea surface temperature from the baseline climate, the 100-year return surge level in Southwest and Southeast Florida will increase by up to 40 centimeters. The considered statistical approaches for extreme surge estimation based on short data sets will be valuable to coastal stakeholders, including urban planners, emergency managers, and the hurricane and storm surge forecasting and warning system.

  19. Active control of surge in centrifugal compressors using magnetic thrust bearing actuation

    Science.gov (United States)

    Sanadgol, Dorsa

    This research presents a new method for active surge control in centrifugal compressors with unshrouded impellers using a magnetic thrust bearing to modulate the impeller tip clearance. Magnetic bearings offer the potential for active control of flow instabilities. This capability is highly dependent on the sensitivity of the compressor characteristics to blade tip clearance. If the position of the shaft can be actuated with sufficient authority and speed, the induced pressure modulation makes control of surge promising. The active nature of the magnetic bearing system makes the real-time static and dynamic positioning of the rotor and therefore modulation of the impeller tip clearance possible. A theoretical model is first established that describes the sensitivity of the centrifugal compressor characteristic curve to tip clearance variations induced by axial motion of the rotor. Results from simulation of the nonlinear model for a single stage high-speed centrifugal compressor show that using the proposed control method, mass flow and pressure oscillations associated with compressor surge are quickly suppressed with acceptable tip clearance excursions, typically less than 20% of the available clearance. It is shown that it is possible to produce adequate axial excursions in the clearance between the impeller blades and the adjacent stationary shroud using a magnetic thrust bearing with practical levels of drive voltage. This surge control method would allow centrifugal compressors to reliably and safely operate with a wider range than is currently done in the field. The principal advantage of the proposed approach over conventional surge control methods lies in that, in machines already equipped with magnetic bearing, the method can potentially be implemented by simply modifying controller software. This dispenses with the need to introduce additional hardware, permitting adaptation of existing machinery at virtually no cost. In addition, since the controller is

  20. Sedimentological recorders of the 2013 Typhoon Haiyan storm surge from contrasting Philippine coastal landscapes

    Science.gov (United States)

    Soria, J. L.; Switzer, A.; Siringan, F. P.; Pilarczyk, J.; Li, L.

    2016-12-01

    Typhoon Haiyan in 2013 was an extremely intense and fast moving typhoon. It claimed more than 6000 lives, caused widespread damage, and affected more than 16 million people along its path in central Philippines. Overwash associated with the 5 to 8 m storm surge of Typhoon Haiyan also left behind a variety of geomorphic and sedimentological imprints, which provide a valuable dataset for modern storm deposits in different landform settings. Here we only present a synthesis of the sedimentological imprints from sites that span clastic, mixed clastic-carbonate, and non-clastic carbonate coasts, and were affected by contrasting surge mechanisms. On the sheltered clastic coast where overwash was dominated by wind-induced setup surge, the overwash sediments occur as a sand unit of no more than 20 cm near the shore, and then spread into sub-cm thin sandsheet that blanket pre-Haiyan soil surfaces up to 1.6 km inland. Thicker sections of the overwash sand exhibit sharp depositional contacts, planar stratification, and generally coarsen upward and fine landward. On the mixed clastic-carbonate coast, the Typhoon Haiyan deposits are generally thin (coast that was affected by a wave-dominated setup surge, the overwash sediments include two distinct assemblages: carbonate boulders now occupying the reef flat surface, and a sand sheet that blanketed the coastal plain up to 300 m distance inland. On the open coast, inverse modeling of flow velocities derived from boulder dimensions, sediment thickness, and grain size distributions indicate that the storm surge travelled across the wide reef flat and inundated the coast with flow velocities exceeding 4 ms-1. The sediment data support the tsunami-like surge characteristics of Haiyan, and although Haiyan's overwash sediments are clearly representative of Philippine modern storm deposits, they should however be used with caution in the interpretation of the geologic record. This cautionary note highlights the continuing issue of

  1. Risk Assessment of Hurricane Storm Surge for Tampa Bay

    Science.gov (United States)

    Lin, N.; Emanuel, K.

    2011-12-01

    Hurricane storm surge presents a major hazard for the United States and many other coastal areas around the world. Risk assessment of current and future hurricane storm surge provides the basis for risk mitigation and related decision making. This study investigates the hurricane surge risk for Tampa Bay, located on the central west coast of Florida. Although fewer storms have made landfall in the central west Florida than in regions farther west in the Gulf of Mexico and the east coast of U.S., Tampa Bay is highly vulnerable to storm surge due to its geophysical features. It is surrounded by low-lying lands, much of which may be inundated by a storm tide of 6 m. Also, edge waves trapped on the west Florida shelf can propagate along the coastline and affect the sea level outside the area of a forced storm surge; Tampa Bay may be affected by storms traversing some distance outside the Bay. Moreover, when the propagation speed of the edge wave is close to that of a storm moving parallel to the coast, resonance may occur and the water elevation in the Bay may be greatly enhanced. Therefore, Tampa Bay is vulnerable to storms with a broad spectrum of characteristics. We apply a model-based risk assessment method to carry out the investigation. To estimate the current surge risk, we apply a statistical/deterministic hurricane model to generate a set of 1500 storms for the Tampa area, under the observed current climate (represented by 1981-2000 statistics) estimated from the NCAR/NCEP reanalysis. To study the effect of climate change, we use four climate models, CNRM-CM3, ECHAM, GFDL-CM2.0, and MIROC3.2, respectively, to drive the hurricane model to generate four sets of 1500 Tampa storms under current climate conditions (represented by 1981-2000 statistics) and another four under future climate conditions of the IPCC-AR4 A1B emission scenario (represented by 2081-2100 statistics). Then, we apply two hydrodynamic models, the Advanced Circulation (ADCIRC) model and the Sea

  2. Application of computer-assisted mapping to volcanic hazard evaluation of surge eruptions: Vulcano, lipari, and vesuvius

    Science.gov (United States)

    Sheridan, Michael F.; Malin, Michael C.

    1983-09-01

    A previously developed computer-assisted model has been applied to several pyroclastic-surge eruptions at three active volcanoes in Italy. Model hazard maps created for various vent locations, eruption types, and mass production rates reasonably reproduced pyroclastic-surge deposits from several recent eruptions on Vulcano, Lipari, and Vesuvius. Small-scale phreatic eruptions on the island of Vulcano (e.g. the 1727 explosion of Forgia Vecchia) pose a limited but serious threat to the village of Porto. The most dangerous zone affected by this type of eruption follows a NNW fissure system between Fossa and Vulcanello. Moderate-sized eruptions on Vulcano, such as those associated with the present Fossa Crater are a much more serious threat to Porto as well as the entire area within the caldera surrounding the cone. The less frequent surge eruptions on Lipari have been even more violent. The extreme mobility of surges like those produced from Monte Guardia (approx. 20,000 y.b.p.) and Monte Pilato would not only threaten the entire island of Lipari, but also the northern part of neighboring Vulcano. Eruptions at Vesuvius with energy and efficiency similar to that of the May 18, 1980 blast of Mount St. Helens would be still more destructive because of the great initial elevation of the summit vent. In addition, surge eruptions at Vesuvius are generally part of more complex eruption cycles that involve several other types of volcanic phenomena including Plinian fall and pyroclastic flows.

  3. A numerical study of vegetation impact on reducing storm surge by wetlands in a semi-enclosed estuary

    Science.gov (United States)

    Kelin, Hu; Qin, Chen; Wang, Hongqing

    2014-01-01

    Coastal wetlands play a unique role in extreme hurricane events. The impact of wetlands on storm surge depends on multiple factors including vegetation, landscape, and storm characteristics. The Delft3D model, in which vegetation effects on flow and turbulence are explicitly incorporated, was applied to the semi-enclosed Breton Sound (BS) estuary in coastal Louisiana to investigate the wetland impact. Guided by extensive field observations, a series of numerical experiments were conducted based on variations of actual vegetation properties and storm parameters from Hurricane Isaac in 2012. Both the vegetation-induced maximum surge reduction (MSR) and maximum surge reduction rate (MSRR) increased with stem height and stem density, and were more sensitive to stem height. The MSR and MSRR decreased significantly with increasing wind intensity. The MSRR was the highest with a fast-moving weak storm. It was also found that the MSRR varied proportionally to the expression involving the maximum bulk velocity and surge over the area of interest, and was more dependent on the maximum bulk surge. Both MSR and MSRR appeared to increase when the area of interest decreased from the whole BS estuary to the upper estuary. Within the range of the numerical experiments, the maximum simulated MSR and MSRR over the upper estuary were 0.7 m and 37%, respectively.

  4. A surge of the glaciers Skobreen–Paulabreen, Svalbard, observed by time-lapse photographs and remote sensing data

    Directory of Open Access Journals (Sweden)

    Lene Kristensen

    2012-11-01

    Full Text Available We present observations of a surge of the glaciers Skobreen–Paulabreen, Svalbard, during 2003–05, including a time-lapse movie of the frontal advance during 2005, Advanced Spaceborne Thermal Emission (ASTER imagery and oblique aerial photographs. The surge initiated in Skobreen, and then propagated downglacier into the lower parts of Paulabreen. ASTER satellite images from different stages of the surge are used to evaluate the surge progression. Features on the glacier surface advanced 2800 m over 2.4 yr, averaging 3.2 m/day, while the front advanced less (ca. 1300 m due to contemporaneous calving. The surge resulted in a lateral displacement of the medial moraines of Paulabreen of ca. 600 m at the glacier front. The time-lapse movie captured the advance of the frontal part of the glacier, and dramatically illustrates glacier dynamic processes in an accessible way. The movie documents a range of processes such as a plug-like flow of the glacier, proglacial thrusting, incorporation of old, dead ice at the margin, and calving into the fjord. The movie provides a useful resource for researchers, educators seeking to teach and inspire students, and those wishing to communicate the fascination of glacier science to a wider public.

  5. Evolution of surge levels inside of the Seine Bay : interactions between tide and surge levels during Johanna and Xynthia storms

    Science.gov (United States)

    Laborie, Vanessya; Sergent, Philippe

    2015-04-01

    Within the Technical Commission for the Study and the Evaluation of Maritime Submersions in the Seine Estuary (CTeeSMES), which aim is to improve the collective knowledge on physical processes related to maritime surge levels, a numerical model of the Atlantic French Coast based on TELEMAC2D was used to study the evolution of surge levels from the ocean to the harbour area of Le Havre and evaluate the interactions between tide and surge levels in the Seine Bay. The numerical model was specifically calibrated on JOHANNA and XYNTHIA storm events, which respectively occurred in March 2008 and in February 2010. To calibrate the global signal (tide + surge levels), measurements available on 18 outputs of the Atlantic coast were used to optimize the coefficient for wind influence and for bottom friction. Maritime boundary conditions were provided by the North East Atlantic Atlas (LEGOS). Winds and pressure fields were CFSR data. Once the numerical model had been calibrated both for tide and surge levels, it has been possible to draw the evolution of surge levels from the ocean to Le Havre (quai Meunier) and then to compare the signal obtained at each point of the Seine Bay with that obtained without taking into consideration tide for each event. That also allowed to evaluate the contribution of interactions between tide and surge levels inside of the Seine Bay for Xynthia and Johanna events, but also for other events in the slice [1979-2010] and considering climate change towards 2100 with IPCC5 scenarios. It appears that instantaneous interactions between tide and surge levels nearly reach 50 % of the global surge levels and can sharply influence the evolution of surge levels in the Seine Bay depending of the moment (high tide or low water) at which the storm occurs.

  6. The dynamics of surges in the 3 February 2015 avalanches in Vallée de la Sionne

    Science.gov (United States)

    Köhler, A.; McElwaine, J. N.; Sovilla, B.; Ash, M.; Brennan, P.

    2016-11-01

    Five avalanches were artificially released at the Vallée de la Sionne test site in the west of Switzerland on 3 February 2015 and recorded by the GEOphysical flow dynamics using pulsed Doppler radAR Mark 3 radar system. The radar beam penetrates the dilute powder cloud and measures reflections from the underlying denser avalanche features allowing the tracking of the flow at 111 Hz with 0.75 m downslope resolution. The data show that the avalanches contain many internal surges. The large or "major" surges originate from the secondary release of slabs. These slabs can each contain more mass than the initial release, and thus can greatly affect the flow dynamics, by unevenly distributing the mass. The small or "minor" surges appear to be a roll wave-like instability, and these can greatly influence the front dynamics as they can repeatedly overtake the leading edge. We analyzed the friction acting on the fronts of minor surges using a Voellmy-like, simple one-dimensional model with frictional resistance and velocity-squared drag. This model fits the data of the overall velocity, but it cannot capture the dynamics and especially the slowing of the minor surges, which requires dramatically varying effective friction. Our findings suggest that current avalanche models based on Voellmy-like friction laws do not accurately describe the physics of the intermittent frontal region of large mixed avalanches. We suggest that these data can only be explained by changes in the snow surface, such as the entrainment of the upper snow layers and the smoothing by earlier flow fronts.

  7. Surge of the Bivachny Glacier in 2012–2015

    Directory of Open Access Journals (Sweden)

    V. M. Kotlyakov

    2015-01-01

    Full Text Available The surge of the Bivachny Glacier that occurred in 2012–2015 is analyzed with the use of photographing performed from International Space Station in 2001–2015 together with data of the satellite monitoring of 1972–2000. This surge happened in 31 years after the similar previous event of 1972–1976. Dynamics of numerous glacier branches causing activation of the lower glacier part that is so called “dead” zone (more than 7 km in length is shown. Just before its stop the front part of the surging glacier had reached the main trunk of the Fedchenko Glacier. 

  8. Mud aprons in front of Svalbard surge moraines: Evidence of subglacial deforming layers or proglacial glaciotectonics?

    Science.gov (United States)

    Kristensen, Lene; Benn, Douglas I.; Hormes, Anne; Ottesen, Dag

    2009-10-01

    Large debris-flow units commonly occur on the distal sides of subaqueous end moraines deposited by surges of Svalbard tidewater glaciers, but have rarely been described in terrestrial settings. Some researchers have argued that these kinds of debris flows reflect processes unique to the subaqueous environment, such as the extrusion of subglacial deforming layers or extensive failure of oversteepened moraine fronts. In this paper, we describe terrestrial and subaqueous parts of a single late Holocene moraine system deposited by a major surge of the tidewater glacier Paulabreen in west Spitsbergen. The ice-marginal landforms on land closely resemble the corresponding landforms on the seabed as evidenced by geomorphic mapping and geophysical profiles from both environments. Both onland and offshore, extensive areas of hummocky moraine occur on the proximal side of the maximum glacier position, and large mud aprons (interpreted as debris flows) occur on the distal side. We show that the debris-flow sediments were pushed in front of the advancing glacier as a continuously failing, mobile push moraine. We propose that the mud aprons are end members of a proglacial landforms continuum that has thrust-block moraines as the opposite end member. Two clusters of dates (~ 8000 YBP and ~ 700 YBP) have previously been interpreted to indicate two separate surges responsible for the moraine formation. New dates suggest that the early cluster indicates a local extinction of the abounded species Chlamys islandica. Other changes corresponding to the widespread 8.2 ka event within the fjord, may suggest that the extinction of the C. islandica corresponds to that time.

  9. Control of Surge in Centrifugal Compressor by Using a Nozzle Injection System: Universality in Optimal Position of Injection Nozzle

    Directory of Open Access Journals (Sweden)

    Toshiyuki Hirano

    2012-01-01

    Full Text Available The passive control method for surge and rotating stall in centrifugal compressors by using a nozzle injection system was proposed to extend the stable operating range to the low flow rate. A part of the flow at the scroll outlet of a compressor was recirculated to an injection nozzle installed on the inner wall of the suction pipe of the compressor through the bypass pipe and injected to the impeller inlet. Two types of compressors were tested at the rotational speeds of 50,000 rpm and 60,000 rpm with the parameter of the circumferential position of the injection nozzle. The present experimental results revealed that the optimum circumferential position, which most effectively reduced the flow rate for the surge inception, existed at the opposite side of the tongue of the scroll against the rotational axis and did not depend on the compressor system and the rotational speeds.

  10. Centrifugal compressor surge detecting method based on wavelet analysis of unsteady pressure fluctuations in typical stages

    Science.gov (United States)

    Izmaylov, R.; Lebedev, A.

    2015-08-01

    Centrifugal compressors are complex energy equipment. Automotive control and protection system should meet the requirements: of operation reliability and durability. In turbocompressors there are at least two dangerous areas: surge and rotating stall. Antisurge protecting systems usually use parametric or feature methods. As a rule industrial system are parametric. The main disadvantages of anti-surge parametric systems are difficulties in mass flow measurements in natural gas pipeline compressor. The principal idea of feature method is based on the experimental fact: as a rule just before the onset of surge rotating or precursor stall established in compressor. In this case the problem consists in detecting of unsteady pressure or velocity fluctuations characteristic signals. Wavelet analysis is the best method for detecting onset of rotating stall in spite of high level of spurious signals (rotating wakes, turbulence, etc.). This method is compatible with state of the art DSP systems of industrial control. Examples of wavelet analysis application for detecting onset of rotating stall in typical stages centrifugal compressor are presented. Experimental investigations include unsteady pressure measurement and sophisticated data acquisition system. Wavelet transforms used biorthogonal wavelets in Mathlab systems.

  11. U.S. Glaucoma Cases Expected to Surge by 2030

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_162924.html U.S. Glaucoma Cases Expected to Surge by 2030 Routine ... Medicine, the National Institutes of Health, or the U.S. Department of Health and Human Services. Recent Health ...

  12. Zika-Linked Birth Defects Surge in Colombia: CDC

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_162464.html Zika-Linked Birth Defects Surge in Colombia: CDC Study ... born with devastating birth defects linked to the Zika virus is no longer confined to Brazil, a ...

  13. Storm surge model based on variational data assimilation method

    Institute of Scientific and Technical Information of China (English)

    Shi-li HUANG; Jian XU; De-guan WANG; Dong-yan LU

    2010-01-01

    By combining computation and observation information,the variational data assimilation method has the ability to eliminate errors caused by the uncertainty of parameters in practical forecasting.It was applied to a storm surge model based on unstructured grids with high spatial resolution meant for improving the forecasting accuracy of the storm surge.By controlling the wind stress drag coefficient,the variation-based model was developed and validated through data assimilation tests in an actual storm surge induced by a typhoon.In the data assimilation tests,the model accurately identified the wind stress drag coefficient and obtained results close to the true state.Then,the actual storm surge induced by Typhoon 0515 was forecast by the developed model,and the results demonstrate its efficiency in practical application.

  14. Observations of cyclone-induced storm surge in coastal Bangladesh

    OpenAIRE

    Chiu, Soyee; Small, Christopher

    2015-01-01

    Water level measurements from 15 tide gauges in the coastal zone of Bangladesh are analyzed in conjunction with cyclone tracks and wind speed data for 54 cyclones between 1977 and 2010. Storm surge magnitude is inferred from residual water levels computed by subtracting modeled astronomical tides from observed water levels at each station. Observed residual water levels are generally smaller than reported storm surge levels for cyclones where both are available, and many cyclones produce no o...

  15. Analysis on Fungal Diversity in Rhizosphere Soil of Continuous Cropping Potato Subjected to Different Furrow-Ridge Mulching Managements

    Directory of Open Access Journals (Sweden)

    Shuhao Qin

    2017-05-01

    Full Text Available Knowledge about fungi diversity following different planting patterns could improve our understanding of soil processes and thus help us to develop sustainable management strategies. The objective of this study was to determine the impact of different furrow-ridge mulching techniques on fungal diversity in rhizosphere soil under continuous cropping system. The investigated treatments were: flat plot without mulch (CK; flat plot with mulch (T1; on-ridge planting with full mulch (T2; on-furrow planting with full mulch (T3; on-ridge planting with half mulch (T4; and on-furrow planting with half mulch (T5. NGS (Illumina methods and ITS1 sequences were used in monitoring fungi diversity of the potato rhizosphere soil. The fungi diversity in the rhizosphere soil was ranked in the order T5 > T2 > T4 > T1 > CK at the early growth stage and T2 > T3 > T1 > T4 > CK at the late growth stage of potato. The fungal communities found in the rhizosphere soil were Ascomycota, Zygomycota, Basidiomycota, Chytridiomycota, and other unidentified fungal communities. Among the fungal community in the rhizosphere soil, Ascomycota was found to be dominant fungi population, with the highest percentage (89% in the T5 soil whereas the T2 soils had the lowest percentage (67%. The Fusarium abundance in fully-mulched treated soils was higher than in half-mulched treated soil. The dominant genus in the T4 soil was Mortierella, whereas lower populations (1–2% of Scutellinia, Cryphonectria, Acremonium, and Alternaria were found in that treatment. Among the eumycetes, the dominant fungal class in all treated soils was the Sordariomycetes, which ranged from 57 to 85% in T2 and T5 soils, respectively. The Fusarium percentages in half-mulched treated soils (T4 and T5 were 55 and 28% lower than that of complete mulched treated soils (T2 and T3, respectively. The cluster analysis results showed that, CK, T4, and T5 treated soils and T1, T2, and T3 treated soils had similarities in

  16. The surge-like eruption of a miniature filament

    Institute of Scientific and Technical Information of China (English)

    Jia-Yan Yang; Yun-Chun Jiang; Dan yang; Yi Bi; Bo Yang; Rui-Sheng Zheng; Jun-Chao Hong

    2012-01-01

    We report on the rare eruption of a miniature Hα filament that took the form of a surge.The filament first underwent a full development within 46 min and then began to erupt 9 min later,followed by a compact,impulsive X-ray class M2.2 flare with a two-ribbon nature only at the early eruption phase.During the eruption,its top rose,whereas the two legs remained rooted in the chromosphere and showed little swelling perpendicular to the rising direction.This led to a surge-like eruption with a narrow angular extent.Similar to the recent observations for standard and blowout X-ray jets by Moore et al.,we thus define it as a "blowout Hα surge." Furthermore,our observations showed that the eruption was associated with (1) a coronal mass ejection guided by a pre-existing streamer,(2) abrupt,significant,and persistent changes in the photospheric magnetic field around the filament,and (3) a sudden disappearance of a small pore.These observations thus provide evidence that a blowout surge is a small-scale version of a large-scale filament eruption in many aspects.Our observations further suggest that at least part of the Hα surges belong to blowout-type cases,and the exact distinction between the standard and blowout Hα surges is important in understanding their different origins and associated eruptive phenomena.

  17. The role of mangroves in attenuating storm surges

    Science.gov (United States)

    Zhang, Keqi; Liu, Huiqing; Li, Yuepeng; Xu, Hongzhou; Shen, Jian; Rhome, Jamie; Smith, J.

    2012-01-01

    Field observations and numerical simulations indicate that the 6-to-30-km-wide mangrove forest along the Gulf Coast of South Florida effectively attenuated stormsurges from a Category 3 hurricane, Wilma, and protected the inland wetland by reducing an inundation area of 1800 km2 and restricting surge inundation inside the mangrove zone. The surge amplitude decreases at a rate of 40–50 cm/km across the mangrove forest and at a rate of 20 cm/km across the areas with a mixture of mangrove islands with open water. In contrast, the amplitudes of stormsurges at the front of the mangrove zone increase by about 10–30% because of the "blockage" of mangroves to surge water, which can cause greater impacts on structures at the front of mangroves than the case without mangroves. The mangrove forest can also protect the wetlands behind the mangrove zone against surge inundation from a Category 5 hurricane with a fast forward speed of 11.2 m/s (25 mph). However, the forest cannot fully attenuate stormsurges from a Category 5 hurricane with a slow forward speed of 2.2 m/s (5 mph) and reduced surges can still affect the wetlands behind the mangrove zone. The effects of widths of mangrove zones on reducing surge amplitudes are nonlinear with large reduction rates (15–30%) for initial width increments and small rates (<5%) for subsequent width increments.

  18. Improved PV system reliability results from surge evaluations at Sandia National Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Russell H. Bonn; Sigifredo Gonzalez

    2000-04-11

    Electrical surges on ac and dc inverter power wiring and diagnostic cables have the potential to shorten the lifetime of power electronics. These surges may be caused by either nearby lightning or capacitor switching transients. This paper contains a description of ongoing surge evaluations of PV power electronics and surge mitigation hardware at Sandia.

  19. Precision Herbicide Application Technologies To Decrease Herbicide Losses in Furrow Irrigation Outflows in a Northeastern Australian Cropping System.

    Science.gov (United States)

    Davis, Aaron M; Pradolin, Jordan

    2016-05-25

    This study compared water quality benefits of using precision herbicide application technologies in relation to traditional spraying approaches across several pre- and postemergent herbicides in furrow-irrigated canefarming systems. The use of shielded sprayers (herbicide banding) provided herbicide load reductions extending substantially beyond simple proportionate decreases in amount of active herbicide ingredient applied to paddocks. These reductions were due largely to the extra management control available to irrigating growers in relation to where both herbicides and irrigation water can be applied to paddocks, coupled with knowledge of herbicide toxicological and physicochemical properties. Despite more complex herbicide mixtures being applied in banded practices, banding provided capacity for greatly reduced environmental toxicity in off-paddock losses. Similar toxicological and loss profiles of alternative herbicides relative to recently regulated pre-emergent herbicides highlight the need for a carefully considered approach to integrating alternative herbicides into improved pest management.

  20. Surge-type glaciers in the Tien Shan (Central Asia)

    Science.gov (United States)

    Mukherjee, Kriti; Bolch, Tobias

    2016-04-01

    Surge-type glaciers in High Mountain Asia are mostly observed in Karakoram and Pamir. However, few surge-type glaciers also exist in the Tien Shan, but have not comprehensively studied in detail in the recent literature. We identified surge-type glaciers in the Tien Shan either from available literature or by manual interpretation using available satellite images (such as Corona, Hexagon, Landsat, SPOT, IRS) for the period 1960 to 2014. We identified 39 possible surge-type glaciers, showing typical characteristics like looped moraines. Twenty-two of them rapidly advanced during different periods or a surge was clearly described in the literature. For the remaining possible surge-type glaciers either the advance, in terms of time and length, were not mentioned in detail in the literature, or the glaciers have remained either stable or retreated during the entire period of our study. Most of the surge-type glaciers cluster in the Inner Tien Shan (especially in the Ak-Shiirak rage) and the Central Tien Shan, are in size and are facing North, West or North West. Pronounced surge events were observed for North Inylchek and Samoilowitsch glaciers, both of which are located in the Central Tien Shan. Samoilowitsch Glacier retreated by more than 3 km between 1960 (length ~8.9 km) and 1992 (~5.8 km), advanced by almost 3 km until 2006 and slightly retreated thereafter. The most pronounced advance occurred between 2000 and 2002. DEM differencing (based on SRTM3 data and stereo Hexagon and Cartosat-1 data) revealed a significant thickening in the middle reaches (reservoir area) of the glacier between 1973 and 2000 while the surface significantly lowered in the middle and upper parts of the glacier between 2000 and 2006. Hence, the ice mass was transferred to the lower reaches (receiving area) and caused the advance with a maximum thickening of more than 80 m. The ~30 km long North Inylchek Glacier retreated since 1943 and showed a very rapid advance of ~3.5 km especially in

  1. CFD Analysis of the Anti-Surge Effects by Water Hammering

    Science.gov (United States)

    Kim, Tae-oh; Jeong, Hyo-min; Chung, Han-shik; Lee, Sin-il; Lee, Kwang-sung

    2015-09-01

    Water hammering occurs due to the surge effect that comes from operating the pump, sudden stop during the operating due to a blackout and rapid open and close of the valve. By the water hammering of the pipeline and the pump, the valve are damaged. In this paper, transient analysis is conducted by CFD (Computational Fluid Dynamics). The purpose of this paper is to provide the research data about the change of the pressure and flow in the pipe that caused by the water hammering.

  2. Experimental and Numerical Investigations of Surge Extension on a Centrifugal Compressor with Vaned Diffuser Using Steam Injection

    Directory of Open Access Journals (Sweden)

    Chuang Gao

    2017-01-01

    Full Text Available This paper presents the first report on surge extension with steam injection through both experimental and numerical simulation. The experimental section covers the test facility, instrumentation, and prestall modes comparison with and without steam injection. It is found that surge extension is not in proportion to injected steam. There exists an upper bound above which deteriorates the margin. Injection of less than 1% of the designed mass flow can bring about over 10% margin improvement. Test results also indicated that steam injection not only damps out prestall waves, but also changes prestall modes and traveling direction. At 90% speed, injection changed the prestall mode from spike to modal, while at 80% speed line, it made the forward traveling wave become backward. Through numerical simulation, location and number of injectors, molecular weight, and temperature of injected gas are modified to explore their influences on surge margin. Similar to the test results, there exists an upper bound for the amount of steam injected. The flow field investigation indicates that this bound is caused by the early trigger of flow collapse due to the injected steam which is similar to the tip leakage flow spillage caused spike stall in axial compressors.

  3. Lethal Thermal Impact at Periphery of Pyroclastic Surges: Evidences at Pompeii

    Science.gov (United States)

    Mastrolorenzo, Giuseppe; Petrone, Pierpaolo; Pappalardo, Lucia; Guarino, Fabio M.

    2010-01-01

    Background The evaluation of mortality of pyroclastic surges and flows (PDCs) produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized. Pompeii and the nearby archaeological sites preserve the most complete set of evidence of the 79 AD catastrophic eruption recording its effects on structures and people. Methodology/Principal Findings Here we investigate the causes of mortality in PDCs at Pompeii and surroundings on the bases of a multidisciplinary volcanological and bio-anthropological study. Field and laboratory study of the eruption products and victims merged with numerical simulations and experiments indicate that heat was the main cause of death of people, heretofore supposed to have died by ash suffocation. Our results show that exposure to at least 250°C hot surges at a distance of 10 kilometres from the vent was sufficient to cause instant death, even if people were sheltered within buildings. Despite the fact that impact force and exposure time to dusty gas declined toward PDCs periphery up to the survival conditions, lethal temperatures were maintained up to the PDCs extreme depositional limits. Conclusions/Significance This evidence indicates that the risk in flow marginal zones could be underestimated by simply assuming that very thin distal deposits, resulting from PDCs with poor total particle load, correspond to negligible effects. Therefore our findings are essential for hazard plans development and for actions aimed to risk mitigation at Vesuvius and other explosive volcanoes. PMID:20559555

  4. Lethal thermal impact at periphery of pyroclastic surges: evidences at Pompeii.

    Directory of Open Access Journals (Sweden)

    Giuseppe Mastrolorenzo

    Full Text Available BACKGROUND: The evaluation of mortality of pyroclastic surges and flows (PDCs produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized. Pompeii and the nearby archaeological sites preserve the most complete set of evidence of the 79 AD catastrophic eruption recording its effects on structures and people. METHODOLOGY/PRINCIPAL FINDINGS: Here we investigate the causes of mortality in PDCs at Pompeii and surroundings on the bases of a multidisciplinary volcanological and bio-anthropological study. Field and laboratory study of the eruption products and victims merged with numerical simulations and experiments indicate that heat was the main cause of death of people, heretofore supposed to have died by ash suffocation. Our results show that exposure to at least 250 degrees C hot surges at a distance of 10 kilometres from the vent was sufficient to cause instant death, even if people were sheltered within buildings. Despite the fact that impact force and exposure time to dusty gas declined toward PDCs periphery up to the survival conditions, lethal temperatures were maintained up to the PDCs extreme depositional limits. CONCLUSIONS/SIGNIFICANCE: This evidence indicates that the risk in flow marginal zones could be underestimated by simply assuming that very thin distal deposits, resulting from PDCs with poor total particle load, correspond to negligible effects. Therefore our findings are essential for hazard plans development and for actions aimed to risk mitigation at Vesuvius and other explosive volcanoes.

  5. Lethal thermal impact at periphery of pyroclastic surges: evidences at Pompeii.

    Science.gov (United States)

    Mastrolorenzo, Giuseppe; Petrone, Pierpaolo; Pappalardo, Lucia; Guarino, Fabio M

    2010-06-15

    The evaluation of mortality of pyroclastic surges and flows (PDCs) produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized. Pompeii and the nearby archaeological sites preserve the most complete set of evidence of the 79 AD catastrophic eruption recording its effects on structures and people. Here we investigate the causes of mortality in PDCs at Pompeii and surroundings on the bases of a multidisciplinary volcanological and bio-anthropological study. Field and laboratory study of the eruption products and victims merged with numerical simulations and experiments indicate that heat was the main cause of death of people, heretofore supposed to have died by ash suffocation. Our results show that exposure to at least 250 degrees C hot surges at a distance of 10 kilometres from the vent was sufficient to cause instant death, even if people were sheltered within buildings. Despite the fact that impact force and exposure time to dusty gas declined toward PDCs periphery up to the survival conditions, lethal temperatures were maintained up to the PDCs extreme depositional limits. This evidence indicates that the risk in flow marginal zones could be underestimated by simply assuming that very thin distal deposits, resulting from PDCs with poor total particle load, correspond to negligible effects. Therefore our findings are essential for hazard plans development and for actions aimed to risk mitigation at Vesuvius and other explosive volcanoes.

  6. Study of a Novel Oscillating Surge Wave Energy Converter: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-08-01

    This study investigates the performance of an oscillating surge wave energy converter (OSWEC) that utilizes adjustable geometry as a means of controlling the hydrodynamic coefficients, a concept originally proposed by [1]. The body of the device consists of a bottom-hinged solid rectangular frame with five horizontal flaps spanning the interior of the frame. The flaps can rotate independently about their center of rotation within the frame like a large window shutter. Changing the orientation of the flaps alters the hydrodynamic coefficients and natural frequency of the device as well as the ability to shed or absorb structural loads accordingly. This ability may allow the device to operate in a wider range of sea states than other current wave energy converter designs. This paper presents and compares the results of numerical simulations and experimental testing of the OSWEC's response to regular waves with all five of the horizontal fin configurations sharing the same orientation of 0 degrees (fully closed interior) and 90 degrees (fully open). The numerical simulations were performed using WAMIT, which calculates hydrodynamic coefficients using a boundary element method code to solve the linear potential flow problem, and WEC-Sim, a MATLAB-based tool that simulates multibody devices in the time domain by solving the governing equations of motion. A 1:14 scale model of the device was built for experimental evaluation in an 8-m-long, 1-m wide wave tank, which supports a water depth of 0.7 m. The OSWEC motion in different wave conditions was measured with displacement sensors while nonlinear wave-structure interaction effects like slamming and overtopping were captured using a high-speed camera and used to understand differences between the simulation and experiments.

  7. Numerical experiments of dynamical processes during the 2011-2013 surge of the Bering-Bagley Glacier System, using a full-Stokes finite element model

    Science.gov (United States)

    Trantow, Thomas

    The Bering-Bagley Glacial System (BBGS) is the largest glacier system outside of the Greenland and Antarctic ice sheets, and is the Earth's largest surge-type glacier. Surging is one of three types of glacial acceleration and the least understood one. Understanding glacial acceleration is paramount when trying to explain ice discharge to the oceans and the glacial contribution to sea-level rise, yet there are currently no numerical glacial models that account for surging. The recent 2011-2013 surge of the BBGS provides a rare opportunity to study the surge process through observations and the subsequent data analysis and numerical modeling. Using radar, altimeter, and image data collected from airborne and satellite missions, various descriptions of ice geometry are created at different times throughout the surge. Using geostatistical estimation techniques including variography and ordinary kriging, surface and bedrock Digital Elevation Maps (DEMs) are derived. A time series analysis of elevation change during the current surge is then conducted and validated using a complete error analysis along with airborne observations. The derived DEMs are then used as inputs to a computer simulated model of glacier dynamics in the BBGS. Using the Finite Element software Elmer/Ice, a full-Stokes simulation, with Glen's flow law for temperate ice, is created for numerical experiments. With consideration of free surface evolution, glacial hydrology and surface mass balance, the model is able to predict a variety of field variables including velocity, stress, strain-rate, pressure and surface elevation change at any point forward in time. These outputs are compared and validated using observational data such as CryoSat-2 altimetry, airborne field data, imagery and previous detailed analysis of the BBGS. Preliminary results reveal that certain surge phenomena such as surface elevation changes, surge progression and locations at which the surge starts, can be recreated using the

  8. Surge and swab pressures in wells with cross-section changes; Pressoes de surge and swab em pocos com variacao de secao

    Energy Technology Data Exchange (ETDEWEB)

    Fedevjcyk, Joao Victor; Junqueira, Silvio Luiz de Mello; Negrao, Cezar Otaviano Ribeiro [Universidade Tecnologica Federal do Parana (UTFPR). Laboratorio de Ciencias Termicas (Lacit) (Brazil)], e-mails: silvio@utfpr.edu.br, negrao@utfpr.edu.br

    2009-12-15

    Well drilling is performed by rotating and applying a weighted drill bit to the geological formation. Well diameter variations and the use of drill pipe accessories might cause changes to the annular cross section space between the drill pipe and the borehole. It should be noted cross section changes influence pressure losses within the well. This study proposes a mathematical/ numerical model to simulate the surge and swab problem in wells with variable cross section areas. The fluid flow yielded by the drill pipe motion is considered to be one-dimensional, isothermal, compressible and transient. The proposed model features the mass and momentum conservation equations, along with a state equation and a constitutive equation for Bingham or Power Law fluids. The governing equations were discretized by the Finite Volume Method. The well is assumed to be impermeable and the drill pipe end to be closed. The results were compared to measured data obtained at the Taquipe experimental well with good agreement. Predictions can now be made as to how changes in cross section areas may significantly affect the transient surge and swab pressures. (author)

  9. Assessing the Impact of Topography on Groundwater Salinization Due to Storm Surge Inundation

    Science.gov (United States)

    Yu, X.; Yang, J.; Graf, T.; Koneshloo, M.; O'Neal, M. A.; Michael, H. A.

    2015-12-01

    The sea-level rise and increase in the frequency and intensity of coastal storms due to climate change are likely to exacerbate adverse effects of storm surges on low-lying coastal areas. The landward flow of water during storm surges introduces salt to surficial coastal aquifers and threatens groundwater resources. Coastal topography (e.g. ponds, dunes, canals) likely has a strong impact on overwash and salinization processes, but is generally highly simplified in modeling studies. To understand the topographic impacts on groundwater salinization, we modeled overwash and variable-density groundwater flow and salt transport in 3D using the fully coupled surface and subsurface numerical simulator, HydroGeoSphere. The model simulates the coastal aquifer as an integrated system considering processes such as overland flow, coupled surface and subsurface exchange, variably saturated flow, and variable-density flow. To represent various coastal landscape types, we started with realistic coastal topography from Delaware, USA, and then generated synthetic fields with differing shore-perpendicular connectivity and surface depressions. The groundwater salinization analysis suggested that the topographic connectivity promoting overland flow controls the volume of aquifer that is salinized. In contrast, depression storage of surface water mainly controls the time for infiltrated salt to flush from the aquifer. The results indicate that for a range of synthetic conditions, topography increases the flushing time of salt by 20-300% relative to an equivalent "simple slope" in which topographic variation is absent. Our study suggests that topography have a significant impact on overwash salinization, with important implications for land management at local scales and groundwater vulnerability assessment at regional to global scales.

  10. Cold surge: a sudden and spatially varying threat to health?

    Science.gov (United States)

    Yang, Tse-Chuan; Wu, Pei-Chih; Chen, Vivian Yi-Ju; Su, Huey-Jen

    2009-05-01

    While cold surge is one of the most conspicuous features of the winter monsoon in East Asia, its impact on human health remains underexplored. Based on the definition by the Central Weather Bureau in Taiwan, we identified four cold surges between 2000 and 2003 and collected the cardiovascular disease mortality data 2 weeks before and 2 weeks after these events. We attempted to answer the following research questions: 1) whether the cold surges impose an adverse and immediate effect on cardiovascular mortality; 2) whether the people living in temperate zones have a higher tolerance of extreme temperature drop than those in the subtropics. With geographic weighting techniques, we not only found that the cardiovascular disease mortality rates increased significantly after the cold surges, but also discovered a spatially varying pattern of tolerance to cold surges. Even within a small study area such as Taiwan, human reaction to severe weather drop differs across space. Needless to say, in the U.S., these findings should be considered in redirecting policy to address populations living in warm places when extreme temperature drops occur.

  11. Application of SCX Language in the Compressor Anti-surge Control Program%SCX语言在压缩机防喘振控制方案中的应用

    Institute of Scientific and Technical Information of China (English)

    何世胜

    2012-01-01

    This paper introduces the application of SCX language in the anti-surge control configuration of the turbo-compressor machine train (4-in-1 machine train) in the nitric acid plant. The surge flow of the compressor has to be determined based on the physical surge test and also the information provided by the compressor vendor. After that, the surge curve is to be worked out by means of the anti surge configuration process in the SCX language. During actual production, a test on the compensated flow is to be made and a judgment to be passed to affirm if the measured value is still in the surge range and see if regulation of the compressor set is necessary. This can effectively control the surge of the compressor set so as to facilitate long-term, safe and stable operation.%介绍了SCX语言在硝酸装置中的“四合一”机组防喘振控制组态中的应用.根据喘振试验确定空压机喘振流量,结合SCX语言编写程序,作出空压机特性曲线,通过判断补偿后流量测量值位置调节机组运行,可有效地控制机组的喘振.

  12. Storm surges in the Western Black Sea. Operational forecasting

    Directory of Open Access Journals (Sweden)

    G. MUNGOV

    2012-12-01

    Full Text Available The frequency of the storm surges in the Black Sea is lower than that in other regions of the World Ocean but they cause significant damages as the magnitude of the sea level set-up is up to 7-8 times greater than that of other sea level variations. New methods and systems for storm surge forecasting and studying their statistical characteristics are absolutely necessary for the purposes of the coastal zone management. The operational forecasting storm surge model of Meteo-France was adopted for the Black Sea in accordance with the bilateral agreement between Meteo-France and NINMH. The model was verified using tide-gauge observations for the strongest storms observed along the Bulgarian coast over the last 10 years.

  13. Observations of cyclone-induced storm surge in coastal Bangladesh

    CERN Document Server

    Chiu, Soyee

    2015-01-01

    Water level measurements from 15 tide gauges in the coastal zone of Bangladesh are analyzed in conjunction with cyclone tracks and wind speed data for 54 cyclones between 1977 and 2010. Storm surge magnitude is inferred from residual water levels computed by subtracting modeled astronomical tides from observed water levels at each station. Observed residual water levels are generally smaller than reported storm surge levels for cyclones where both are available, and many cyclones produce no obvious residual at all. Both maximum and minimum residual water levels are higher for west-landing cyclones producing onshore winds and generally diminish for cyclones making landfall on the Bangladesh coast or eastward producing offshore winds. Water levels observed during cyclones are generally more strongly influenced by tidal phase and amplitude than by storm surge alone. In only 7 of the 15 stations does the highest plausible observed water level coincide with a cyclone. While cyclone-coincident residual water level ...

  14. A numerical storm surge forecast model with Kalman filter

    Institute of Scientific and Technical Information of China (English)

    Yu Fujiang; Zhang Zhanhai; Lin Yihua

    2001-01-01

    Kalman filter data assimilation technique is incorporated into a standard two-dimensional linear storm surge model. Imperfect model equation and imperfect meteorological forcimg are accounted for by adding noise terms to the momentum equations. The deterministic model output is corrected by using the available tidal gauge station data. The stationary Kalman filter algorithm for the model domain is calculated by an iterative procedure using specified information on the inaccuracies in the momentum equations and specified error information for the observations. An application to a real storm surge that occurred in the summer of 1956 in the East China Sea is performed by means of this data assimilation technique. The result shows that Kalman filter is useful for storm surge forecast and hindcast.

  15. Electromagnetic computation methods for lightning surge protection studies

    CERN Document Server

    Baba, Yoshihiro

    2016-01-01

    This book is the first to consolidate current research and to examine the theories of electromagnetic computation methods in relation to lightning surge protection. The authors introduce and compare existing electromagnetic computation methods such as the method of moments (MOM), the partial element equivalent circuit (PEEC), the finite element method (FEM), the transmission-line modeling (TLM) method, and the finite-difference time-domain (FDTD) method. The application of FDTD method to lightning protection studies is a topic that has matured through many practical applications in the past decade, and the authors explain the derivation of Maxwell's equations required by the FDTD, and modeling of various electrical components needed in computing lightning electromagnetic fields and surges with the FDTD method. The book describes the application of FDTD method to current and emerging problems of lightning surge protection of continuously more complex installations, particularly in critical infrastructures of e...

  16. Community health facility preparedness for a cholera surge in Haiti.

    Science.gov (United States)

    Mobula, Linda Meta; Jacquet, Gabrielle A; Weinhauer, Kristin; Alcidas, Gladys; Thomas, Hans-Muller; Burnham, Gilbert

    2013-01-01

    With increasing population displacement and worsening water insecurity after the 2010 earthquake, Haiti experienced a large cholera outbreak. Our goal was to evaluate the strengths and weaknesses of seven community health facilities' ability to respond to a surge in cholera cases. Since 2010, Catholic Relief Services (CRS) with a number of public and private donors has been working with seven health facilities in an effort to reduce morbidity and mortality from cholera infection. In November 2012, CRS through the Centers for Disease Control and Prevention (CDC)'s support, asked the Johns Hopkins Center for Refugee and Disaster Response to conduct a cholera surge simulation tabletop exercise at these health facilities to improve each facility's response in the event of a cholera surge. Using simulation development guidelines from the Pan American Health Organization and others, a simulation scenario script was produced that included situations of differing severity, supply chain, as well as a surge of patients. A total of 119 hospital staff from seven sites participated in the simulation exercise including community health workers, clinicians, managers, pharmacists, cleaners, and security guards. Clinics that had challenges during the simulated clinical care of patients were those that did not appropriately treat all cholera patients according to protocol, particularly those that were vulnerable, those that would need additional staff to properly treat patients during a surge of cholera, and those that required a better inventory of supplies. Simulation-based activities have the potential to identify healthcare delivery system vulnerabilities that are amenable to intervention prior to a cholera surge.

  17. Wave-Tide-Surge Coupled Simulation for Typhoon Maemi

    Institute of Scientific and Technical Information of China (English)

    Byung Ho Choi; Byung Il Min; Kyeong Ok Kim; Jin Hee Yuk

    2013-01-01

    The main task of this study focuses on studying the effect of wave-current interaction on currents,storm surge and wind wave as well as effects of current induced wave refraction and current on waves by using numerical models which consider the bottom boundary layer and sea surface roughness parameter for shallow and smooth bed area around Korean Peninsula.The coupled system (unstructured-mesh SWAN wave and ADCIRC) run on the same unstructured mesh.This identical and homogeneous mesh allows the physics of wave-circulation interactions to be correctly resolved in both models.The unstructured mesh can be applied to a large domain allowing all energy from deep to shallow waters to be seamlessly followed.There is no nesting or overlapping of structured wave meshes,and no interpolation is required.In response to typhoon Maemi (2003),all model components were validated independently,and shown to provide a faithful representation of the system's response to this storm.The waves and storm surge were allowed to develop on the continental shelf and interact with the complex nearshore environment.The resulting modeling system can be used extensively for prediction of the typhoon surge.The result show that it is important to incorporate the wave-current interaction effect into coastal area in the wave-tide-surge coupled model.At the same time,it should consider effects of depth-induced wave breaking,wind field,currents and sea surface elevation in prediction of waves.Specially,we found that:(1) wave radiation stress enhanced the current and surge elevation otherwise wave enhanced nonlinear bottom boundary layer decreased that,(2) wind wave was significantly controlled by sea surface roughness thus we cautiously took the experimental expression.The resulting modeling system can be used for hindcasting (prediction) the wave-tide-surge coupled environments at complex coastline,shallow water and fine sediment area like areas around Korean Peninsula.

  18. Suspension-Driven Gravity Surges on Horizontal Surfaces: Effect of the Initial Shape

    Science.gov (United States)

    Zgheib, Nadim; Bonometti, Thomas; Balachandar, S.

    2016-11-01

    We present results from fully-resolved direct numerical simulations of canonical (axisymmetric and planar) and non-canonical (rectangular) configurations of horizontal suspension-driven gravity surges. We show that the dynamics along the initial minor and major axis of a rectangular release are roughly similar to that of a planar and axisymmetric current, respectively. However, contrary to expectation, we observe under certain conditions the final extent of the deposit from finite releases to surpass that from an equivalent planar current. This is attributed to a converging flow of the particle-laden mixture towards the initial minor axis, a behaviour that was previously reported for scalar-driven currents on uniform slopes. This flow is observed to be correlated with the travelling of a perturbation wave generated at the extremity of the longest side that reaches the front of the shortest side in a finite time. A semi-empirical explicit expression (based on established relations for planar and axisymmetric currents) is proposed to predict the extent of the deposit in the entire x-y plane. Finally we observe that for the same initial volume of a suspension-driven gravity surge, a release of larger initial horizontal aspect-ratio is able to retain particles in suspension for longer periods of time. ExxonMobil Upstream Research (EM 09296); NSF (OISE-0968313); CALMIP (P1525).

  19. Into the Surge of Network-driven Innovation

    DEFF Research Database (Denmark)

    Østergaard, Claus Møller; Rosenstand, Claus Andreas Foss; Gertsen, Frank

    2013-01-01

    The ambition of this paper is to provide a better theoretical understanding of innovation by framing it in a long historical, economical, and societal perspective. The research question of the paper is: What characterize the historical surges of innovation? Based on previous works and research...... this is examined from the 1880’s up until today. The contribution of the paper is a societal perspective on innovation, where the difference between industrial society and knowledge society leads into the surge of network-driven innovation. Network-driven innovation is unfolded on top of the known cost- driven...

  20. Probabilistic Storm Surge Hazard Assessment in the French West Indies

    Science.gov (United States)

    Krien, Y.; Dudon, B.; Roger, J.; Zahibo, N.; Arnaud, G.

    2016-12-01

    The French West Indies are prone to hurricanes formed over the warm tropical waters of the Atlantic Ocean and Caribbean Sea. These events can have great consequences in terms of human, property, and economic losses. Storm surge hazard assessment is therefore required to provide guidance to emergency managers and decision-makers. By combining statistical-deterministic approaches and wave-current coupled models, we assessed storm surge hazard in Guadeloupe and Martinique islands. We present here the methodology, the results, as well as the on-going work on the impact of climate change in the framework of the FEDER-funded project C3AF.

  1. A High Resolution Forecast Model of Storm Surge Inundation

    Institute of Scientific and Technical Information of China (English)

    LIU Juan; JIANG Wensheng; SUN Wenxin; WANG Yongzhi

    2005-01-01

    In order to forecast storm surge inundation, a two-dimensional model is established. In the model, an alternating computation sequence method is used to solve the governing equations, and the dry and wet method is introduced to treat the moving boundary. This model is easy to use. It has a friendly input interface and Arcview GIS is used as the output interface. The model is applied to the Shantou area to simulate the storm surge elevations and inundations caused by Typhoons 6903 ane 0104 using the same relevant parameters. The calculated results agree well with the observations.

  2. Surge of the Bivachny Glacier in 2012–2015

    OpenAIRE

    V. M. Kotlyakov; L. V. Desinov; V. A. Rudakov

    2015-01-01

    The surge of the Bivachny Glacier that occurred in 2012–2015 is analyzed with the use of photographing performed from International Space Station in 2001–2015 together with data of the satellite monitoring of 1972–2000. This surge happened in 31 years after the similar previous event of 1972–1976. Dynamics of numerous glacier branches causing activation of the lower glacier part that is so called “dead” zone (more than 7 km in length) is shown. Just before its stop the front part of the surgi...

  3. NUMERICAL STUDY OF THE INFLUENCE OF WAVES AND TIDE-SURGE INTERACTION ON TIDE-SURGES IN THE BOHAI SEA

    Institute of Scientific and Technical Information of China (English)

    尹宝树; 侯一筠; 程明华; 苏京志; 林明祥; 李明悝; M.I.El-Sabh

    2001-01-01

    Abstract The author's combined numerical model consisting of a third generation shallow water wave model and a 3-D tide-surge model with wave-dependent surface wind stress were used to study the influence of waves on fide-surge motion. For the typical weather case, in this study, the magnitude and mechanism of the influence of waves on tide-surges in the Bohai Sea were revealed for the first time. The results showed that although consideration of the wave-dependent surface wind stresses raise slightly the traditional surface wind stress, due to the accumulated effects, the computed results are improved on the whole. Storm level maximum modulation can reach 0.4 m. The results computed by the combined model agreed well with the measured data.

  4. NUMERICAL STUDY OF THE INFLUENCE OF WAVES AND TIDE- SURGE INTERACTION ON TIDE-SURGES IN THE BOHAI SEA

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The author's combined numerical model consisting of a third generation shallow water wave model and a 3-D tide-surge model with wave-dependent surface wind stress were used to study the influence of waves on tide-surge motion. For the typical weather case, in this study, the magnitude and mechanism of the influence of waves on tide-surges in the Bohai Sea were revealed for the first time. The results showed that although consideration of the wave-dependent surface wind stresses raise slightly the traditional surface wind stress, due to the accumulated effects, the computed results are improved on the whole. Storm level maximum modulation can reach 0.4 m. The results computed by the combined model agreed well with the measured data.

  5. Stall/surge dynamics of a multi-stage air compressor in response to a load transient of a hybrid solid oxide fuel cell-gas turbine system

    Science.gov (United States)

    Azizi, Mohammad Ali; Brouwer, Jacob

    2017-10-01

    A better understanding of turbulent unsteady flows in gas turbine systems is necessary to design and control compressors for hybrid fuel cell-gas turbine systems. Compressor stall/surge analysis for a 4 MW hybrid solid oxide fuel cell-gas turbine system for locomotive applications is performed based upon a 1.7 MW multi-stage air compressor. Control strategies are applied to prevent operation of the hybrid SOFC-GT beyond the stall/surge lines of the compressor. Computational fluid dynamics tools are used to simulate the flow distribution and instabilities near the stall/surge line. The results show that a 1.7 MW system compressor like that of a Kawasaki gas turbine is an appropriate choice among the industrial compressors to be used in a 4 MW locomotive SOFC-GT with topping cycle design. The multi-stage radial design of the compressor enhances the ability of the compressor to maintain air flow rate during transient step-load changes. These transient step-load changes are exhibited in many potential applications for SOFC/GT systems. The compressor provides sustained air flow rate during the mild stall/surge event that occurs due to the transient step-load change that is applied, indicating that this type of compressor is well-suited for this hybrid application.

  6. Modelling and Quasilinear Control of Compressor Surge and Rotating Stall Vibrations

    Directory of Open Access Journals (Sweden)

    Ranjan Vepa

    2010-01-01

    Full Text Available An unsteady nonlinear and extended version of the Moore-Greitzer model is developed to facilitate the synthesis of a quasilinear stall vibration controller. The controller is synthesised in two steps. The first step defines the equilibrium point and ensures that the desired equilibrium point is stable. In the second step, the margin of stability at the equilibrium point is tuned or increased by an appropriate feedback of change in the mass flow rate about the steady mass flow rate at the compressor exit. The relatively simple and systematic non-linear modelling and linear controller synthesis approach adopted in this paper clearly highlights the main features on the controller that is capable of inhibiting compressor surge and rotating stall vibrations. Moreover, the method can be adopted for any axial compressor provided its steady-state compressor and throttle maps are known.

  7. Fate and transport of furrow-applied granular tefluthrin and seed-coated clothianidin insecticides: Comparison of field-scale observations and model estimates.

    Science.gov (United States)

    Huff Hartz, Kara E; Edwards, Tracye M; Lydy, Michael J

    2017-05-30

    The transport of agricultural insecticides to water bodies may create risk of exposure to non-target organisms. Similarly, widespread use of furrow-applied and seed-coated insecticides may increase risk of exposure, yet accessible exposure models are not easily adapted for furrow application, and only a few examples of model validation of furrow-applied insecticides exist using actual field data. The goal of the current project was to apply an exposure model, the Pesticide in Water Calculator (PWC), to estimate the concentrations of two in-furrow insecticides applied to maize: the granular pyrethroid, tefluthrin, and the seed-coated neonicotinoid, clothianidin. The concentrations of tefluthrin and clothianidin in surface runoff water, sampled from a field in central Illinois (USA), were compared to the PWC modeled pesticide concentrations in surface runoff. The tefluthrin concentrations were used to optimize the application method in the PWC, and the addition of particulate matter and guttation droplets improved the models prediction of clothianidin concentrations. Next, the tefluthrin and clothianidin concentrations were calculated for a standard farm pond using both the optimized application method and the application methods provided in PWC. Estimated concentrations in a standard farm pond varied by a factor of 100 for tefluthrin and 50 for clothianidin depending on the application method used. The addition of guttation droplets and particulate matter to the model increased the annual clothianidin concentration in a standard farm pond by a factor of 1.5, which suggested that these transport routes should also be considered when assessing neonicotinoid exposure.

  8. Aging assessment of surge protective devices in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J.F.; Subudhi, M. [Brookhaven National Lab., Upton, NY (United States); Carroll, D.P. [Florida Univ., Gainesville, FL (United States)

    1996-01-01

    An assessment was performed to determine the effects of aging on the performance and availability of surge protective devices (SPDs), used in electrical power and control systems in nuclear power plants. Although SPDs have not been classified as safety-related, they are risk-important because they can minimize the initiating event frequencies associated with loss of offsite power and reactor trips. Conversely, their failure due to age might cause some of those initiating events, e.g., through short circuit failure modes, or by allowing deterioration of the safety-related component(s) they are protecting from overvoltages, perhaps preventing a reactor trip, from an open circuit failure mode. From the data evaluated during 1980--1994, it was found that failures of surge arresters and suppressers by short circuits were neither a significant risk nor safety concern, and there were no failures of surge suppressers preventing a reactor trip. Simulations, using the ElectroMagnetic Transients Program (EMTP) were performed to determine the adequacy of high voltage surge arresters.

  9. Why Teen Mental Ability Surges While Brain Shrinks

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_166310.html Why Teen Mental Ability Surges While Brain Shrinks Researchers say they may have answer to ... behavior keep scaling up," he said. So while teens lose brain volume and girls have lower brain volume than ...

  10. 14 CFR 33.65 - Surge and stall characteristics.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Surge and stall characteristics. 33.65 Section 33.65 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... stall characteristics. When the engine is operated in accordance with operating instructions required...

  11. Monitoring Inland Storm Surge and Flooding from Hurricane Rita

    Science.gov (United States)

    McGee, Benton D.; Tollett, Roland W.; Mason, Jr., Robert R.

    2006-01-01

    Pressure transducers (sensors) and high-water marks were used to document the inland water levels related to storm surge generated by Hurricane Rita in southwestern Louisiana and southeastern Texas. On September 22-23, 2005, an experimental monitoring network of sensors was deployed at 33 sites over an area of about 4,000 square miles to record the timing, extent, and magnitude of inland hurricane storm surge and coastal flooding. Sensors were programmed to record date and time, temperature, and barometric or water pressure. Water pressure was corrected for changes in barometric pressure and salinity. Elevation surveys using global-positioning systems and differential levels were used to relate all storm-surge water-level data, reference marks, benchmarks, sensor measuring points, and high-water marks to the North American Vertical Datum of 1988 (NAVD 88). The resulting data indicated that storm-surge water levels over 14 feet above NAVD 88 occurred at three locations, and rates of water-level rise greater than 5 feet per hour occurred at three locations near the Louisiana coast.

  12. ISSN 2073-9990 East Cent. Afr. J. surg

    African Journals Online (AJOL)

    Hp 630 Dual Core

    COSECSA/ASEA Publication - East and Central African Journal of Surgery. December 2016; Vol. .... shorter duration (median of 20 weeks vs. 3.5 weeks, p 0.029). .... inguinal hernia in children: laparoscopic or open? Eur J Ped Surg 2011; 21: ...

  13. Debris entrainment and landform genesis during tidewater glacier surges

    Science.gov (United States)

    Lovell, Harold; Fleming, Edward J.; Benn, Douglas I.; Hubbard, Bryn; Lukas, Sven; Rea, Brice R.; Noormets, Riko; Flink, Anne E.

    2015-08-01

    The englacial entrainment of basal debris during surges presents an opportunity to investigate processes acting at the glacier bed. The subsequent melt-out of debris-rich englacial structures during the quiescent phase produces geometrical ridge networks on glacier forelands that are diagnostic of surge activity. We investigate the link between debris entrainment and proglacial geomorphology by analyzing basal ice, englacial structures, and ridge networks exposed at the margins of Tunabreen, a tidewater surge-type glacier in Svalbard. The basal ice facies display clear evidence for brittle and ductile tectonic deformation, resulting in overall thickening of the basal ice sequence. The formation of debris-poor dispersed facies ice is the result of strain-induced metamorphism of meteoric ice near the bed. Debris-rich englacial structures display a variety of characteristics and morphologies and are interpreted to represent the incorporation and elevation of subglacial till via the squeezing of till into basal crevasses and hydrofracture exploitation of thrust faults, reoriented crevasse squeezes, and preexisting fractures. These structures are observed to melt-out and form embryonic geometrical ridge networks at the base of a terrestrially grounded ice cliff. Ridge networks are also located at the terrestrial margins of Tunabreen, neighboring Von Postbreen, and in a submarine position within Tempelfjorden. Analysis of network characteristics allows these ridges to be linked to different formational mechanisms of their parent debris-rich englacial structures. This in turn provides an insight into variations in the dominant tectonic stress regimes acting across the glacier during surges.

  14. On the Response of Interleaved Transformer Windings to Surge Voltages

    DEFF Research Database (Denmark)

    Pedersen, A.

    1963-01-01

    The high series capacitance theory for the response of interleaved transformer windings to surge voltages is criticized from the point of view that an increased series capacitance as a result of interleaving is incompatible with the concept of a pure capacitive initial voltage distribution. A new...

  15. Predicting paleohydraulics from storm surge and tsunami deposits: Using experiments to improve inverse model accuracy

    Science.gov (United States)

    Johnson, Joel P. L.; Delbecq, Katie; Kim, Wonsuck

    2017-04-01

    How accurately can flow depths and velocities of storm surges and tsunamis be predicted from sedimentary deposits? Inverse models have been proposed to quantify hydrodynamics from suspended sediment deposits, but assumptions about how deposit grain size distributions (GSDs) are influenced by flow characteristics remain largely untested. Using laboratory experiments, we evaluate an existing advection-settling model in which suspended sediment transport is assumed to reflect horizontal advection (constraining flow velocity) and vertical settling from the water surface (constraining depth). While the original model assumed that depth and velocity would be best predicted by the deposit D95 (the diameter for which 95% of the cumulative GSD is finer), we find that the median deposit size (D50) tends to better predict mean flow hydraulics. Two key factors influencing how flow characteristics control deposit GSDs are (a) dispersion caused by turbulence and (b) the transport distance required for suspension and settling to effectively sort grains. Deposits proximal to sediment sources primarily reflect the source GSD, while deposits farther from the source preferentially represent transport-dependent sorting. In our experimental data, transport distances longer than 1-2 advection length scales are required for the deposit GSD to reasonably predict flow depths and velocities. These results suggest ways that event deposits can be used to more accurately assess coastal risks from tsunamis and storm waves.

  16. Changing the guard: Polymer replaces porcelain for surge arresters

    Energy Technology Data Exchange (ETDEWEB)

    Skytt, T.; Gleimar, H. E. G.

    2002-07-01

    Surge arresters are safety devices which quickly and effectively limit the over voltages that can arise in transmission networks following lightning, switching and other transient events. The earliest forms of overvoltage protection, a simple air gap between electrodes, have long since been replaced by a new generation of gapless arresters with series-connected, non-linear zinc oxide varistors contained in a porcelain housing. Now these porcelain type surge arresters are being replaced by a new type, called PEXLIM (Polymeric EXcellent LIMiter), which uses the same block of zinc oxide as the porcelain type, but its housing is made of silicon rubber, a polymer. The new lightweight insulation material shows a number of properties superior to the porcelain, such as enhanced product safety and ease of handling. It is also more durable, resilient, yet solid and compact, water-repellent, lightweight, resistant to aging or light or ultra-violet radiation, as well as fire, has good electrical properties, and is environmentally friendly since it does not contain any substances harmful to the environment. These properties make this new type of surge arrester highly suitable for use in earthquake-prone areas; it can also replace more expensive and maintenance-intensive equipment. Having successfully broken into the lower voltage systems, these new type of surge arresters are now rapidly gaining ground at the higher voltage levels. ABB, the developer of PEXLIM, has already supplied these arresters to North America for use in an 800-kV grid. As further proof of its growing popularity, last year PEXLIM made up over half of the surge arrester production for applications up to and including 245 kV. 1 tab., 6 figs.

  17. A basis function approach for exploring the seasonal and spatial features of storm surge events

    Science.gov (United States)

    Wu, Wenyan; Westra, Seth; Leonard, Michael

    2017-07-01

    Storm surge is a significant contributor to flooding in coastal and estuarine regions. To represent the statistical characteristics of storm surge over a climatologically diverse region, we propose the use of basis functions that capture the temporal progression of individual storm surge events. This extends statistical analyses of surge from considering only the peak to a more multifaceted approach that also includes decay rate and duration. Our results show that there is seasonal variation in storm surge along the Australian coastline. During the dominant storm surge seasons, the peak and duration of storm surge events tend to increase simultaneously at a number of locations, with implications for flood damage assessments and evacuation planning. By combining the dynamic and statistical features of storm surge, it is possible to better understand the factors that can lead to flood risk along the coastline, including estuarine areas that are also affected by fluvial floods.

  18. Storm surge in the Bay of Bengal and Arabian Sea: The problem and its prediction

    Digital Repository Service at National Institute of Oceanography (India)

    Dube, S.K.; Rao, A.D.; Sinha, P.C.; Murty, T.S.; Bahulayan, N.

    India and its neighbourhood is threatened by the possibility of storm surge floods whenever a tropical cyclone approaches. Storm surge disasters cause heavy loss of life and property, damage to the coastal structures and agriculture nwhich lead...

  19. Brief Communication: On the magnitude and frequency of Khurdopin glacier surge events

    OpenAIRE

    D. J. Quincey; Luckman, A.

    2014-01-01

    The return periods of Karakoram glacier surges are poorly quantified. Here, we present evidence of an historic surge of the Khurdopin Glacier that began in the mid-1970s and peaked in 1979. Measured surface displacements reached >5 km a−1, two orders of magnitude faster than during quiescence. The Khurdopin Glacier next surged in the late 1990s, equating to a return period of 20 years. Surge evolution in the two events shows remarkable similarity suggesting a common trigger....

  20. [Effects of ridge and furrow rain harvesting with supplemental irrigation on winter wheat photosynthetic characteristics, yield and water use efficiency in Guanzhong irrigation district].

    Science.gov (United States)

    Zhang, Yu; Han, Qing-fang; Cheng, Xue-feng; Yang, Shan-shan; Jia, Zhi-kuan; Ding, Rui-xia; Ren, Xiao-long; Nie, Jun-feng

    2015-05-01

    A field experiment was conducted to determine the regulation of crop photosynthesis and output and water saving effect under ridge and furrow rain harvesting with supplemental irrigation in Guanzhong irrigation district. The experiment was set with 5 treatments with irrigation at returning green stage, and the widths of both ridge and furrow being 60 cm. T1, T2 and T3 were in the ridge and furrow rain harvesting planting pattern, with the irrigation volumes being 0, 375 and 750 m3 · hm(-2) respectively, T4 was flat planting with irrigation (border irrigation) of 750 m3 · hm(-2) and CK was flat planting without irrigation. Effects on winter wheat photosynthetic organs, photosynthetic rate, yield and water use efficiency, etc. were tested. The results showed that compared with T4, T1, T2 and T3 treatments increased the grain yield by 2.8%, 9.6% and 18.9%, improved the harvest index by 2.0% to 8.5%, advanced the flag leaf chlorophyll content by 41.9% to 64.4% significantly, and improved the 0-40 cm layer soil moisture content by 0.1%-4.6% during the whole growth period. Photosynthetic rates at the flowering and filling stages also increased by 22.3% to 54.2% and -4.3% to 67.2%, respectively. Total water use efficiencies (WUEy) were 17.9%, 10.4% and 15.4% higher than that of T4, and 69.3%, 58.6% and 65.7% higher than that of CK (P water use efficiencies (IUE) were 119.1% and 18.8% higher than that of T4, respectively. Therefore, it was concluded that ridge and furrow rain harvesting cultivation could maintain higher grain yield than border irrigation without irrigation or with irrigation reduction by 50%. The utilization efficiency of irrigation water under the condition of irrigation reduction by 50% was improved significantly, and the ridge and furrow rain harvesting could significantly improve whole cropland water use efficiency in the year of less rainfall.

  1. Furrow-irrigated chufa crops in Valencia (Spain. I: Productive response to two irrigation strategies

    Directory of Open Access Journals (Sweden)

    N. Pascual-Seva

    2013-01-01

    Full Text Available Chufa (Cyperus esculentus L. var. sativus Boeck. is an important vegetable crop in Valencia (Spain, where its tubers are used to produce a refreshing drink called 'horchata'. Water is relatively inexpensive, there are no data regarding the volumes of water used to grow chufa, and the irrigation water use efficiency (IWUE has neither been determined. The aim of this research was to compare the productive responses of the chufa crop to two irrigation strategies (IS. The volumetric soil water content (VSWC was monitored with capacitance sensors. Trends in VSWC were used to determine the in situ field capacity (FC, beginning each irrigation event when the VSWC reached either approximately 45% (H1 or 60% (H2 of the FC at a soil depth of 0.10 m. The experiments were conducted over three consecutive seasons. An area velocity flow module measured the water flow. The yields, the water volumes used, and the IWUE were calculated. Plants were periodically sampled and the harvest index and relative growth rate were determined. The yield was affected by the year and by the IS. The greatest yields were obtained with the H2 strategy (on average 2.18 kg m-2 for H2 vs. 1.94 kg m-2 for H1; p≤0.01, and the average tuber weight (ATW was affected (p≤0.01 by the year and IS interaction. IWUE was affected by the year, and none of the considered factors affected the harvest index (p≤0.05. It can be concluded that maintaining a higher VSWC would increase both yield and ATW without affecting IWUE.

  2. 30 CFR 57.16002 - Bins, hoppers, silos, tanks, and surge piles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Bins, hoppers, silos, tanks, and surge piles... NONMETAL MINES Materials Storage and Handling § 57.16002 Bins, hoppers, silos, tanks, and surge piles. (a) Bins, hoppers, silos, tanks, and surge piles, where loose unconsolidated materials are stored,...

  3. 30 CFR 56.16002 - Bins, hoppers, silos, tanks, and surge piles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Bins, hoppers, silos, tanks, and surge piles... MINES Materials Storage and Handling § 56.16002 Bins, hoppers, silos, tanks, and surge piles. (a) Bins, hoppers, silos, tanks, and surge piles, where loose unconsolidated materials are stored, handled...

  4. THE STUDY OF ALLOCATION OF SURGE BUNKER IN MINE HAULAGE SYSTEM

    Institute of Scientific and Technical Information of China (English)

    王喜富; 张幼蒂; 张达贤

    1997-01-01

    Based on the function analysis of surge bunker in mine haulage system, the authors raise the calculation methods of the total output of a mine haulage system. Taking the maximum of system's total throughput as a objective, the method of determining the surge bunker's rational size is put forward. Also, the problems of rational position of surge bunker are analysesed.

  5. A model study of Abrahamsenbreen, a surging glacier in northern Spitsbergen

    NARCIS (Netherlands)

    Oerlemans, J.; van Pelt, W. J. J.

    2015-01-01

    The climate sensitivity of Abrahamsenbreen, a 20 km long surge-type glacier in northern Spitsbergen, is studied with a simple glacier model. A scheme to describe the surges is included, which makes it possible to account for the effect of surges on the total mass budget of the glacier. A climate rec

  6. Numerical model for surge and swab pressures on wells with cross-section variation

    Energy Technology Data Exchange (ETDEWEB)

    Fedevjcyk, Joao Victor; Junqueira, Silvio Luiz de Mello; Negrao, Cezar Otaviano Ribeiro [UTFPR - Federal University of Technology - Parana - Curitiba, PR (Brazil)], e-mails: silvio@utfpr.edu.br, negrao@utfpr.edu.br

    2010-07-01

    Drilling is one of the most complex steps in petroleum exploration. The process is accomplished by rotating a drill bit to compress the rock formation. During drilling, a fluid is pumped into the well to lubricate and cool down the drill bit, to clean up the well, to avoid the formation fluid influx to the well and also to stabilize the borehole walls. Fluid circulation, however, can be interrupted for maintenance reasons and the drill pipe can be moved to remove the drill bit. The downward or upward movement of the drill pipe displaces the fluid within the well causing either under pressure (swab) or over pressure (surge), respectively. If the pressure at the well bore overcomes the formation fracture pressure, a loss of circulation can take place. On the other way round, the upward movement may reduce the pressure below the pore pressure and an inflow of fluid to the well (kick) can occur. An uncontrolled kick may cause a blowout with serious damages. The transient flow induced by the axial movement of the drill pipe is responsible for the pressure changes at the well bore. Nevertheless, the well bore cross section variation may modify the pressure change within the pipe. In this paper, the effects of diameter variation of the drilling well on the surge and swab pressures are investigated. The equations that represent the phenomenon (mass and momentum conservation) are discretized by the finite volume method. Despite its non-Newtonian properties, the fluid is considered Newtonian in this first work. The drill pipe is considered closed and the flow is assumed as single-phased, one-dimensional, isothermal, laminar, compressible and transient. A sensitivity analysis of the flow parameters is carried out. The cross-section changes cause the reflection of the pressure wave, and consequently pressure oscillations. (author)

  7. Building and Analyzing SURGEDAT: The World's Most Comprehensive Storm Surge Database

    Science.gov (United States)

    Needham, H.; Keim, B.

    2012-12-01

    SURGEDAT, the world's most comprehensive tropical storm surge database, has identified and mapped the location and height of hundreds of global storm surge events. This project originated with a study that identified more than 200 tropical surge events along the U.S. Gulf Coast. Spatial analysis of these data reveal that the central and western Gulf Coast observe more frequent and higher magnitude surges, whereas much of the eastern Gulf Coast, including the west coast of Florida, experiences less storm surge activity. Basin-wide return period analysis of these data estimate a 100-year return period of 8.20m, and a 10-year return period of 4.95m. Return period analysis of 10 sub-regions within the basin reveal that the highest surge levels occur in the Southeast Louisiana/ Mississippi zone, which includes the New Orleans metropolitan area. The 100-year surge level in this zone is estimated to be 7.67m. The Southeast Texas/ Southwest Louisiana zone, which includes the Houston metropolitan area, has the second highest surge levels, with a 100-year storm surge estimate of 6.30m. Surge levels are lower on the west coast of Florida, where the 100-year surge level is estimated between three and four meters. Expansion of this work includes mapping all high water marks for each surge event and the creation of a search-by-location web tool, which enables users to see the entire storm surge history for specific locations. In addition, the dataset has expanded internationally and now includes more than 500 surge events, as surges have now been identified in all the major ocean basins that experience tropical cyclones. International partnerships are sought to further expand this work, particularly in Australia, China, Japan, Philippines, India, Bangladesh, Myanmar, Mexico and various countries in Oceania and the Caribbean.; ;

  8. Analysis on Lightning Surge Propagation in Wind Farm

    Science.gov (United States)

    Yasuda, Yoh; Hara, Takehisa; Funabashi, Toshihisa

    Wind power generation is expected to become more important in the future distribution system. Although several prospective reports such as IEC 61400-24 and NREL SR-500-31115 indicate on insulation scheme and grounding design for lightning protection, it still seems that there are not many investigations on the problems. This paper therefore discusses lightning surge analysis using wind farm model with 2 or 10 ideal wind turbines. Changing parameters such as grounding resistance and lightning strike points, several cases were studied. As the result of the analysis using digital simulator ARENE, it is clear that the surge tends to propagate toward the end of a distribution line in a wind farm and there is possibility of insulation accidents at the other wind turbines when lightning attacks a wind turbine.

  9. RESEARCH ON THE CONDITION TO SET A TAILRACE SURGE TANK

    Institute of Scientific and Technical Information of China (English)

    ZHAO Gui-lian; YANG jian-dong; XU Yuan-jie; LI Jin-ping

    2004-01-01

    When using the draft-tube vacuum to be less than 8.0m as the rule to set a tailrace surge tank, a mixing function that describes the process of water-hammer vacuum and velocity-head vacuum varied with time is proposed, on the assumption that the guide vane of the hydraulic turbine and the turbine discharge were all changed linearly. An exact maximum of the draft-tube vacuum for the first-phase water-hammer and the last-phase water-hammer is obtained. Finally a much more reasonable formula of critical tailrace length is derived. The results of two cases show that the formula proposed can determine correctly and reasonably whether a tailrace surge tank is needed or not, and are more suitable for project design than the formula suggested by the specification.

  10. Use of historical information in extreme storm surges frequency analysis

    Science.gov (United States)

    Hamdi, Yasser; Duluc, Claire-Marie; Deville, Yves; Bardet, Lise; Rebour, Vincent

    2013-04-01

    The prevention of storm surge flood risks is critical for protection and design of coastal facilities to very low probabilities of failure. The effective protection requires the use of a statistical analysis approach having a solid theoretical motivation. Relating extreme storm surges to their frequency of occurrence using probability distributions has been a common issue since 1950s. The engineer needs to determine the storm surge of a given return period, i.e., the storm surge quantile or design storm surge. Traditional methods for determining such a quantile have been generally based on data from the systematic record alone. However, the statistical extrapolation, to estimate storm surges corresponding to high return periods, is seriously contaminated by sampling and model uncertainty if data are available for a relatively limited period. This has motivated the development of approaches to enlarge the sample extreme values beyond the systematic period. The nonsystematic data occurred before the systematic period is called historical information. During the last three decades, the value of using historical information as a nonsystematic data in frequency analysis has been recognized by several authors. The basic hypothesis in statistical modeling of historical information is that a perception threshold exists and that during a giving historical period preceding the period of tide gauging, all exceedances of this threshold have been recorded. Historical information prior to the systematic records may arise from high-sea water marks left by extreme surges on the coastal areas. It can also be retrieved from archives, old books, earliest newspapers, damage reports, unpublished written records and interviews with local residents. A plotting position formula, to compute empirical probabilities based on systematic and historical data, is used in this communication paper. The objective of the present work is to examine the potential gain in estimation accuracy with the

  11. Rapid Response Measurements of Hurricane Waves and Storm Surge

    Science.gov (United States)

    Gravois, U.

    2010-12-01

    Andrew (1992), Katrina (2005), and Ike (2008) are recent examples of extensive damage that resulted from direct hurricane landfall. Some of the worst damages from these hurricanes are caused by wind driven waves and storm surge flooding. The potential for more hurricane disasters like these continues to increase as a result of population growth and real estate development in low elevation coastal regions. Observational measurements of hurricane waves and storm surge play an important role in future mitigation efforts, yet permanent wave buoy moorings and tide stations are more sparse than desired. This research has developed a rapid response method using helicopters to install temporary wave and surge gauges ahead of hurricane landfall. These temporary installations, with target depths from 10-15 m and 1-7 km offshore depending on the local shelf slope, increase the density of measurement points where the worst conditions are expected. The method has progressed to an operational state and has successfully responded to storms Ernesto (2006), Noel (2007), Fay (2008), Gustav (2008), Hanna (2008) and Ike (2008). The temporary gauges are pressure data loggers that measure at 1 Hz continuously for 12 days and are post-processed to extract surge and wave information. For the six storms studied, 45 out of 49 sensors were recovered by boat led scuba diver search teams, with 43 providing useful data for an 88 percent success rate. As part of the 20 sensor Hurricane Gustav response, sensors were also deployed in lakes and bays inLouisiana, east of the Mississippi river delta. Gustav was the largest deployment to date. Generally efforts were scaled back for storms that were not anticipated to be highly destructive. For example, the cumulative total of sensors deployed for Ernesto, Noel, Fay and Hanna was only 20. Measurement locations for Gustav spanned over 800 km of exposed coastline from Louisiana to Florida with sensors in close proximity to landfall near Cocodrie

  12. Source of a Prominent Poleward Surge During Solar Cycle 24

    CERN Document Server

    Yeates, A R; van Driel-Gesztelyi, L

    2015-01-01

    As an observational case study, we consider the origin of a prominent poleward surge of leading polarity, visible in the magnetic butterfly diagram during Solar Cycle 24. A new technique is developed for assimilating individual regions of strong magnetic flux into a surface flux transport model. By isolating the contribution of each of these regions, the model shows the surge to originate primarily in a single high-latitude activity group consisting of a bipolar active region present in Carrington Rotations 2104-05 (November 2010-January 2011) and a multipolar active region in Rotations 2107-08 (February-April 2011). This group had a strong axial dipole moment opposed to Joy's law. On the other hand, the modelling suggests that the transient influence of this group on the butterfly diagram will not be matched by a large long-term contribution to the polar field, because of its location at high latitude. This is in accordance with previous flux transport models.

  13. The colonic groove or furrow: a comparative morphological study of six species of African mole-rats (Rodentia, Bathyergidae).

    Science.gov (United States)

    Kotzé, S H; van der Merwe, E L; Ndou, R; O'Riain, M J; Bennett, N C

    2009-08-01

    Herbivorous mammals such as nutrias, guinea pigs, chinchillas, and mole-rats have a longitudinal mucosal colonic groove (furrow) in their ascending colon, which is thought to play a role in the colonic separation mechanism (CSM). It is not known whether this groove is structurally modified to adapt to this function in mole-rat species. The morphology of this groove was studied in 32 mol-rats, four species, one of which consisted of three subspecies, endemic to southern Africa and two species found in eastern Africa. The macroscopic morphology of the groove was documented, and samples for histological examination were taken. The groove was wide at its origin at the cecocolic junction and was lined on either side by a row of papillae with the opposing papillae slightly offset in arrangement. The papillated groove gradually decreased in size toward the distal part of the ascending colon where it disappeared. This pattern was similar in all species except in Heterocephalus glaber, where the papillae were absent and the groove was lined by two longitudinal ridges. A histological examination of cross sections revealed that the mucosa covering the inner and outer walls of the groove was rich in mucous-secreting goblet cells. The walls of the groove contained smooth muscle extending from the inner circular smooth muscle layer at the base to the tips of the papillae in all species examined as well as arteries, lymphatic vessels, and prominent sinusoid-like veins. The groove could be demonstrated both macroscopically and histologically in three Bathyergus suillus fetuses of varying sizes. The sinusoid-like veins present in all grooves, regardless of macroscopic shape, suggest that they have a role in the functioning of the groove. (c) 2009 Wiley-Liss, Inc.

  14. Reducing Ammonia Volatilization from Maize Fields with Separation of Nitrogen Fertilizer and Water in an Alternating Furrow Irrigation System

    Institute of Scientific and Technical Information of China (English)

    HAN Kun; ZHOU Chun-ju; WANG Lin-quan

    2014-01-01

    The objective of this 2-yr field trial, with a central composite rotatable design, was to assess and quantify the effects of separation of nitrogen fertilizer and water with alternating furrow irrigation (SNWAFI) practices on soil ammonia (NH3) emission during the summer maize (Zea mays L.) growing season. Ammonia volatilization after N sidedress and irrigation ranged from 4.8 to 17.0 kg N ha-1 and 6.2 to 20.6 kg N ha-1, respectively, in 2008 and 2009. The lower N input contributed to lower NH3 loss but lower yield, whereas the higher N input induced higher yield as well as higher NH3 loss. Ammonia intensity (NH3 volatilization per crop yield) after N sidedress and irrigation was 1.2-3.0 kg NH3-N t-1 yield in 2008 and 1.1-3.2 kg NH3-N t-1 yield in 2009. The predicted minimum NH3 intensity in 2008 was 1.6 kg NH3-N t-1 yield and was obtained with the combined application of 127 kg N ha-1 and 108 mm irrigation water. In 2009, the predicted minimum NH3 intensity was 1.3 kg NH3-N t-1 yield and was obtained with the combined application of 101 kg N ha-1 and 83 mm irrigation water. We conclude that SNWAFI practices with optimum rates of water and fertilizer can signiifcantly reduce soil NH3 intensity and maintain yield. It was more beneifcial for sustainable farming strategies to minimize the NH3 intensity rather than reduce absolute NH3 emissions alone.

  15. The Effect of Plastic-Covered Ridge and Furrow Planting on the Grain Filling and Hormonal Changes of Winter Wheat

    Institute of Scientific and Technical Information of China (English)

    LIU Yang; HAN Juan; WEN Xiao-xia; WU Wei; GUO Qiang; ZENG Ai; LIAO Yun-cheng

    2013-01-01

    Although plastic-covered ridge and furrow planting (RF) has been reported to produce substantial increases in the grain weight of winter wheat, the underlying mechanism is not yet understood. The present study used two cultivars, Xinong 538 and Zhoumai 18, and RF and traditional lfatten planting (TF, control) with the objective of investigating the effect of RF on wheat grain iflling and the possible relationship of hormonal changes in the wheat grains under RF to grain iflling. The results indicated that RF signiifcantly increased the grain weight, although the effects on grain iflling were different: RF signiifcantly increased the grain-iflling rate and grain weight of inferior grains, whereas RF had no signiifcant effect on grain-iflling rate and grain weight of superior grains. The ifnal grain weight of inferior grains under RF was 39.1 and 50.7 mg for Xinong 538 and Zhoumai 18, respectively, 3.6 and 3.4 mg higher than the values under TF. However, the ifnal grain weight of superior grains under RF was only 0.6 and 0.8 mg higher than under TF for Xinong 538 and Zhoumai 18, respectively. RF signiifcantly decreased the ethylene and gibberellic acid content in the inferior grains and increased the indole-3-acetic acid, abscisic acid and zeatin+zeatin riboside content in the inferior grains; however, no signiifcant difference between RF and TF was observed for the hormonal content in the superior grains. Based on these results, we concluded that RF signiifcantly modulated hormonal changes in the inferior grains and, thus, affected the grain iflling and grain weight of the inferior grains;in contrast, RF had no signiifcant effect on grain iflling, grain weight and hormonal changes in the superior wheat grains.

  16. Controlling near shore nonlinear surging waves through bottom boundary conditions

    CERN Document Server

    Mukherjee, Abhik; Kundu, Anjan

    2016-01-01

    Instead of taking the usual passive view for warning of near shore surging waves including extreme waves like tsunamis, we aim to study the possibility of intervening and controlling nonlinear surface waves through the feedback boundary effect at the bottom. It has been shown through analytic result that the controlled leakage at the bottom may regulate the surface solitary wave amplitude opposing the hazardous variable depth effect. The theoretical results are applied to a real coastal bathymetry in India.

  17. Wildlife Poaching: Africa’s Surging Trafficking Threat

    Science.gov (United States)

    2014-05-01

    called keratin, an inert substance that is similar in composition to human fingernails and hair. Some of the consequences of wildlife trafficking are...of the few central figures to have been convicted is a Thai trafficker named Chumlong Lem- tongthai, who worked for businesses in Thailand and Laos...4 1 Wildlife Poaching: Africa’s Surging Trafficking Threat By Bradley anderson and Johan Jooste u Spikes in the prices of ivory and rhino horn have

  18. Enkephalin surges in dorsal neostriatum as a signal to eat

    OpenAIRE

    DiFeliceantonio, Alexandra G.; Mabrouk, Omar S.; Kennedy, Robert T.; C. Berridge, Kent

    2012-01-01

    Compulsive over-consumption of rewards characterizes disorders ranging from binge eating to drug addiction. Here, we provide evidence that enkephalin surges in an anteromedial quadrant of dorsal neostriatum contribute to generating intense consumption of palatable food. In ventral striatum, mu opioid circuitry contributes an important component of motivation to consume rewards [1–4]. In dorsal neostriatum, mu opioid receptors are concentrated within striosomes that receive inputs from limbic ...

  19. Population vulnerability to storm surge flooding in coastal Virginia, USA.

    Science.gov (United States)

    Liu, Hua; Behr, Joshua G; Diaz, Rafael

    2016-07-01

    This study aims to assess the vulnerability of populations to storm surge flooding in 12 coastal localities of Virginia, USA. Population vulnerability is assessed by way of 3 physical factors (elevation, slope, and storm surge category), 3 built-up components (road availability, access to hospitals, and access to shelters), and 3 household conditions (storm preparedness, financial constraints to recovering from severe weather events, and health fragility). Fuzzy analysis is used to generate maps illustrating variation in several types of population vulnerability across the region. When considering physical factors and household conditions, the most vulnerable neighborhoods to sea level rise and storm surge flooding are largely found in urban areas. However, when considering access to critical infrastructure, we find rural residents to be more vulnerable than nonrural residents. These detailed assessments can inform both local and state governments in catastrophic planning. In addition, the methodology may be generalized to assess vulnerability in other coastal corridors and communities. The originality is highlighted by evaluating socioeconomic conditions at refined scale, incorporating a broader range of human perceptions and predispositions, and employing a geoinformatics approach combining physical, built-up, and socioeconomic conditions for population vulnerability assessment. Integr Environ Assess Manag 2016;12:500-509. © 2015 SETAC. © 2015 SETAC.

  20. Mass balance, runoff and surges of Bering Glacier, Alaska

    Directory of Open Access Journals (Sweden)

    W. Tangborn

    2013-05-01

    Full Text Available The historical net, ablation and accumulation daily balances, as well as runoff of Bering Glacier, Alaska are determined for the 1951–2011 period with the PTAA (precipitation-temperature-area-altitude model, using daily precipitation and temperature observations collected at the Cordova and Yakutat weather stations, together with the area-altitude distribution of the glacier. The model mean annual balance for this 61 yr period is −0.6 m w.e., the accumulation balance is +1.4 and the ablation balance is −2.0 m w.e. Average annual runoff is 2.5 m w.e. Periodic surges of this glacier transport large volumes of ice to lower elevations where the ablation rate is higher, producing more negative balances and increasing runoff. Runoff from Bering Glacier (derived from simulated ablation and precipitation as rain is highly correlated with four of the glacier surges that have occurred since 1951. Ice volume loss for the 1972–2003 period measured with the PTAA model is 2.7 km3 w.e. a−1 and closely agrees with losses for the same period measured with the geodetic method. It is proposed that the timing and magnitude of daily snow accumulation and runoff, both of which are controlled by the glacier's area-altitude distribution and are calculated with the PTAA model, can be used to determine the probability that a glacier will surge.

  1. Hospitals Capability in Response to Disasters Considering Surge Capacity Approach

    Directory of Open Access Journals (Sweden)

    Gholamreza Khademipour

    2016-01-01

    Full Text Available Background: The man-made and natural disasters have adverse effects with sound, apparent, and unknown consequences. Among various components of disaster management in health sector, the most important role is performed by health-treatment systems, especially hospitals. Therefore, the present study aimed to evaluate the surge capacity of hospitals of Kerman Province in disaster in 2015. Materials and Methods: This is a quantitative study, conducted on private, military, and medical sciences hospitals of Kerman Province. The sampling method was total count and data collection for the research was done by questionnaire. The first section of the questionnaire included demographic information of the studied hospitals and second part examined the hospital capacity in response to disasters in 4 fields of equipment, physical space, human resources, and applied programs. The extracted data were analyzed by descriptive statistics. Results: The mean capability of implementing the surge capacity programs by hospitals of Kerman Province in disasters and in 4 fields of equipment, physical space, human resources, and applied programs was evaluated as 7.33% (weak. The surge capacity capability of state hospitals in disasters was computed as 8% and compared to private hospitals (6.07% had a more suitable condition. Conclusion: Based on the results of study and significance of preparedness of hospitals in response to disasters, it is proposed that managers of studied hospitals take measures to promote the hospital response capacity to disasters based on 4 components of increasing hospital capacity.

  2. Using satellite altimetry and tide gauges for storm surge warning

    Science.gov (United States)

    Andersen, O. B.; Cheng, Y.; Deng, X.; Steward, M.; Gharineiat, Z.

    2015-03-01

    The combination of the coarse temporal sampling by satellite altimeters in the deep ocean with the high temporal sampling at sparsely located tide gauges along the coast has been used to improve the forecast of high water for the North Sea along the Danish Coast and for the northeast coast of Australia. For both locations we have tried to investigate the possibilities and limitations of the use of satellite altimetry to capture high frequency signals (surges) using data from the past 20 years. The two regions are chosen to represent extra-tropical and tropical storm surge conditions. We have selected several representative high water events on the two continents based on tide gauge recordings and investigated the capability of satellite altimetry to capture these events in the sea surface height data. Due to the lack of recent surges in the North Sea we focused on general high water level and found that in the presence of two or more satellites we could capture more than 90% of the high water sea level events. In the Great Barrier Reef section of the northeast Australian coast, we have investigated several large tropical cyclones; one of these being Cyclone Larry, which hit the Queensland coast in March 2006 and caused both loss of lives as well as huge devastation. Here we demonstrate the importance of integrating tide gauges with satellite altimetry for forecasting high water at the city of Townsville in northeast Australia.

  3. Mass balance, runoff and surges of the Bering Glacier, Alaska

    Directory of Open Access Journals (Sweden)

    W. Tangborn

    2012-12-01

    Full Text Available The historical net, ablation and accumulation daily balances and runoff of the Bering Glacier, Alaska are determined for the 1951–2011 period with the PTAA (precipitation-temperature-area-altitude model, using daily precipitation and temperature observations collected at the Cordova and Yakutat weather stations, together with the area-altitude distribution of the glacier. The mean annual balance for this 61-yr period is −0.6 mwe, the accumulation balance is +1.4 and the ablation balance is −2.0 mwe. Periodic surges of this glacier transport large volumes of ice to lower elevations where the ablation rate is higher, producing more negative balances and increasing runoff. During the 1993–1995 surge the average ablation balance is −3.3 mwe, over a meter greater than the 1951–2011 average. Runoff from the Bering Glacier (derived from simulated ablation and precipitation as rain is highly correlated with the four glacier surges that have been observed since 1951. Ice volume loss for the 1972–2003 period measured with the PTAA model is 2.3 km3 we a−1 and closely agrees with losses for the same period measured with the geodetic method.

  4. H{α} Surges Aroused by Newly-emerging Satellite Bipolar Magnetic Field

    Science.gov (United States)

    Wang, J. F.; Zhou, T. H.; Ji, H. S.

    2013-07-01

    An Hα surge event occurred at AR NOAA 11259 on 2011 July 22. According to the BBSO (Big Bear Solar Observatory) Hα line-center observations, three surges continuously ejected from the same region to the north of the main-sunspot of AR 11259. All of surges ejected along a straight trajectory, and looked like the reversed Eiffel Tower. The first and second surges had the same process. Two bright points firstly appeared to the north of the main-sunspot. After several minutes, a surge appeared between the two bright points, and then rapidly ejected when the two points got most brightness.When the surge reached the maximum height, it disappeared quickly. However, the third surge appeared without bright points, and its height was only half of the others. Compared with SDO/HMI (Solar Dynamics Observatory/Helioseismic and Magnetic Imager) line-of-sight magnetogram, more than one hour before the first surge appeared, a satellite bipolar magnetic field emerged from the surge-ejection region. The newly-emerging positive magnetic flux showed a distinct decrease several minutes earlier than the ejection of the surges. We assumed that the surges was associated with the reconnection between the newly-emerging bipolar magnetic field and the existing (sunspot) magnetic field.

  5. Can we use crevasse fill ridges for identifying undocumented surge behavior in Svalbard?

    Science.gov (United States)

    Farnsworth, W. R.; Ingolfsson, O.; Schomacker, A.; Retelle, M.

    2015-12-01

    Documenting glaciers that exhibit surge type behavior is crucial, especially as we attempt to use evidence of ice front fluctuations for reconstructing past climate oscillations. Controversy exists regarding the relationship between surge activity and climatic processes such as mass balance. This project identifies undocumented surge type glaciers in Svalbard based on the presence of crevasse fill ridges (CFRs) visible in glacier forelands. Although it is acknowledged that many Svalbard outlet glaciers surge, estimates vary greatly as to the actual number of surge- type glaciers in Svalbard, and their distribution pattern is not well understood. A detailed survey of recent (2008-2011), high resolution imagery from Toposvalbard, provided by the Norwegian Polar Institute, allowed for a rapid analysis of Svalbard outlet glaciers. Using CFRs as indicators of surge behavior has almost doubled the amount of potential surge-type glaciers in central Spitsbergen. This method also highlights numerous other glaciers of potential surge type behavior throughout the archipelago. Limits to the CFR identification method are discussed. Additionally as the forelands of previously reported surge type glaciers were analyzed for CFRs, it was evident that the surge indicators were only present in approximately half of the forelands. Numerous factors control the formation and preservation of CFRs including; glacier size, bedrock lithology, subglacial sediments and clast size as well as glacial fluvial run-off. This poster focuses on the controlling factors for CFR formation and preservation as well as other potential methods for effectively identifying surge behavior.

  6. Response to the sudden closure of St. Vincent's Hospital: learning from a real, no-notice, prolonged surge event.

    Science.gov (United States)

    Adalja, Amesh A; Watson, Matthew; Wollner, Samuel; Rambhia, Kunal J; Toner, Eric S

    2011-06-01

    We qualitatively examined the impact of the permanent closure of St. Vincent's Hospital in New York City on the remaining hospitals in the area and analyzed how these hospitals responded to this event. We conducted a descriptive survey consisting of interviews with clinical (n = 24) and administrative (n = 11) staff from 4 hospitals in lower Manhattan after the sudden closure of St. Vincent's Hospital. These hospitals experienced a sudden and sustained increase in patient volume. Each was faced with specific constraints (eg, finances, physical plant, bureaucracy), but they developed similar strategic responses. Generally applicable principles included: soliciting innovative ideas from clinical staff, reexamining previous proposals to improve efficiency, fast-tracking stalled capacity-building projects, and focusing on improving patient care and flow. Three broad tactical themes were apparent: increases in staff and staff hours, use of alternative sites of care, and implementing novel ways of operating. The impact on hospital operations resulting from the closure of St. Vincent's Hospital is a surrogate medical surge event and met thresholds for activating emergency operations plans. Novel operating methods used in response to this surge event offer practical and broadly applicable principles that might improve medical surge management in other hospitals.

  7. Coupled modeling of storm surge and coastal inundation: A case study in New York City during Hurricane Sandy

    Science.gov (United States)

    Yin, Jie; Lin, Ning; Yu, Dapeng

    2016-11-01

    In this paper, we describe a new method of modeling coastal inundation arising from storm surge by coupling a widely used storm surge model (ADCIRC) and an urban flood inundation model (FloodMap). This is the first time the coupling of such models is implemented and tested using real events. The method offers a flexible and efficient procedure for applying detailed ADCIRC storm surge modeling results along the coastal boundary (with typical resolution of ˜100 m) to FloodMap for fine resolution inundation modeling (Hurricane Sandy was simulated at both the city (New York City) and subregional (lower Manhattan) scales with various resolutions. Results obtained from the ADCIRC and coupled ADCIRC-FloodMap simulations were compared with the recorded (high water marks) and derived (inundation extent based on the planar method) data from FEMA. At the city scale, coupled ADCIRC-FloodMap modeling demonstrates improved prediction over ADCIRC modeling alone for both the extent and depth of inundation. The advantage of the coupled model is further illustrated in the subregional modeling, using a mesh resolution of 3 m which is substantially finer than the inland mesh resolution used by ADCIRC (>70 m). In further testing, we explored the effects of mesh resolution and roughness specification. Results agree with previous studies that fine resolution is essential for capturing intricate flow paths and connectivity in urban topography. While the specification of roughness is more challenging for urban environments, it may be empirically optimized. The successful coupling of ADCIRC and FloodMap models for fine resolution coastal inundation modeling unlocks the potential for undertaking large numbers of probabilistically based synthetic surge events for street-level risk analysis.

  8. Base surge deposits, eruption history, and depositional processes of a wet phreatomagmatic volcano in Central Anatolia (Cora Maar)

    Science.gov (United States)

    Gençalioğlu-Kuşcu, Gonca; Atilla, Cüneyt; Cas, Ray A. F.; Kuşcu, İlkay

    2007-01-01

    Cora Maar is a Quaternary volcano located to the 20 km northwest of Mount Erciyes, the largest of the 19 polygenetic volcanic complexes of the Cappadocian Volcanic Province in central Anatolia. Cora Maar is a typical example of a maar-diatreme volcano with a nearly circular crater with a mean diameter of c.1.2 km, and a well-bedded base surge-dominated maar rim tephra sequence up to 40 m in thickness. Having a diameter/depth ratio ( D/ d) of 12, Cora is a relatively "mature" maar compared to recent maar craters in the world. Cora crater is excavated within the andesitic lava flows of Quaternary age. The tephra sequence is not indurated, and consists of juvenile clasts up to 70 cm, non-juvenile clasts up to 130 cm, accretionary lapilli up to 1.2 cm in diameter, and ash to lapilli-sized tephra. Base surge layers display well-developed antidune structures indicating the direction of the transport. Both progressive and regressive dune structures are present within the tephra sequence. Wavelength values increase with increasing wave height, and with large wavelength and height values. Cora tephra display similarities to Taal and Laacher See base surge deposits. Impact sags and small channel structures are also common. Lateral and vertical facies changes are observed for the dune bedded and planar bedsets. According to granulometric analyses, Cora Maar tephra samples display a bimodal distribution with a wide range of Md φ values, characteristic for the surge deposits. Very poorly sorted, bimodal ash deposits generally vary from coarse tail to fine tail grading depending on the grain size distribution while very poorly sorted lapilli and block-rich deposits display a positive skewness due to fine tail grading.

  9. Monitoring of surge tanks in hydroelectric power plants using fuzzy control; Ueberwachung von Wasserschloessern in Wasserkraftwerken mit Fuzzy-Control

    Energy Technology Data Exchange (ETDEWEB)

    Lin, J.C.

    2000-07-01

    Surge tanks are used to reduce pressure variations caused by fluid transients in high-head hydroelectric power plants. Occasionally load increases have to be limited to prevent the surge tank from draining due to excessive demands of flow. A control concept based on fuzzy logic was developed for governing the load changes of hydroelectric power plants. In order to achieve an optimal control behaviour and simultaneously to avoid the draining of surge tanks, the speed of load increases is automatically adjusted by a fuzzy conclusion depending on the height and the gradient of the water level in the surge tank, the reservoir level and the sum of load increases. The hydroelectric power plant Achensee of Tiroler Wasserkraftwerke AG in Austria is taken as an example to demonstrate the characteristics of the control concept. In comparison with a conventional control concept, the operation of load increases using the fuzzy concept proves to be more flexible and unrestricted. (orig.) [German] Ein Wasserschloss dient zur Verminderung von Druckschwankungen im Wasserfuehrungssystem von Hochdruckanlagen. Gelegentlich muss man die Lastaufnahme so beschraenken, dass das Wasserschloss nicht durch uebermaessige Wasserentnahme leerlaeuft. Fuer die Leistungsregelung eines Wasserkraftwerks wurde ein Konzept entwickelt, das auf der Fuzzy-Control in Verbindung mit der klassischen Regelung beruht. Um ein optimales Regelverhalten zu erhalten und gleichzeitig das Leerlaufen des Wasserschlosses zu vermeiden, wird die Geschwindigkeit der Lastaufnahme in Abhaengigkeit von der Hoehenkote und dem Gradienten des Wasserschlosspegels, dem Pegel des Oberwassers und der Groesse der geforderten Lasterhoehung automatisch eingestellt. Die Untersuchung erfolgt am Beispiel des Achenseekraftwerkes der Tiroler Wasserkraftwerke AG, Oesterreich. Im Vergleich mit einer konventionellen Regelung ergibt sich mit dem Fuzzy-Konzept eine flexiblere und freizuegigere Lastaufnahme. (orig.)

  10. On the physical mechanisms governing self-excited pressure surge in Francis turbines

    Science.gov (United States)

    Müller, A.; Favrel, A.; Landry, C.; Yamamoto, K.; Avellan, F.

    2014-03-01

    The required operating range for hydraulic machines is continually extended in an effort to integrate renewable energy sources with unsteady power outputs into the existing electrical grid. The off-design operation however brings forth unfavorable flow patterns in the machine, causing dynamic problems involving cavitation, which may represent a limiting factor to the energy production. In Francis turbines it is observed that the self-excited oscillation of a vortex rope in the draft tube cone prevents the delivery of maximum power when required. This phenomenon is referred to as full load pressure surge and has been the object of extensive research during the past decades. Several contributions deepened its understanding through measurement and simulation of the local flow properties and the global stability parameters. The draft tube pressure level and the runner outlet swirl are identified as key variables in the modelling of the vortex rope dynamics. Recently, a cyclic appearance of blade cavitation has been observed at overload conditions in a multiphase numerical simulation coupling the runner and the draft tube. From the analysis of the simulation it becomes obvious that the cyclic appearance of blade cavitation has a direct effect on the runner outlet swirl, thus introducing an additional interaction mechanism that is not accounted for in formerly published models. For the presented work, the results of this numerical study are confirmed experimentally on a reduced scale model of a Francis turbine. Several wall pressure measurements in the draft tube cone are performed, together with high speed visualizations of the vortex rope and the blade cavitation. The flow swirl is calculated based on Laser Doppler Velocimetry measurements. A possible mechanism explaining the coupling between the self-excited pressure and vortex rope oscillation and the cyclic appearance of the blade cavitation is proposed. Furthermore, the streamwise propagation speed of the flow

  11. THEORETICAL,NUMERICAL AND EXPERIMENTAL STUDY OF WATER HAMMER IN PIPE SYSTEM WITH COLUMN SURGE CHAMBER

    Institute of Scientific and Technical Information of China (English)

    Zhou Ze-xuan; Tan Soon Keat

    2003-01-01

    A new kind of governing equations for water hammer based on the elastic column theory was proposed and adopted to analyse water hammer phenomenon in the pipe system with a vertical column surge chamber and water level fluctuation in the surge chamber during pressure transient. The wrongness existing in the classical governing equations for water hammer was analysed. A typical reservoir-valve pipe system was chosen as an example to verify the new governing equations numerically and experimentally. The finite difference method based on the method of characteristics was used to solve numerically the nonlinear characteristic equations. The temporal evolutions of transient volume flux and head and of water level fluctuation for various surge chamber configurations were worked out, assuming that the air in the surge chamber are compressible. The relevant experiment was conducted to verify the new governing equations and numerical method. The numerical and experimental results show that the new governing equations are valid and the conventional assumption that the pressure head at the base of a surge chamber equals that of the static head above it during pressure transient is not always valid. The surge chamber generally reises the period of transient pressure wave in pipe system, reduces the maximum pressure envelope and lifts the minimum envelope substantially. The water level fluctuation in the surge chamber was numerically and experimentally observed. Increasing the size of the surge chamber and/or decreasing the initial air pressure in the surge chamber enhance the effectiveness of the surge chamber in suppressing pressure wave.

  12. Effect of hurricane paths on storm surge response at Tianjin, China

    Science.gov (United States)

    Feng, Xingru; Yin, Baoshu; Yang, Dezhou

    2012-06-01

    A hurricane induced storm surge simulation system was developed for Tianjin coast, which consists of a hurricane model and a storm surge model. The peak storm surge result of the simulation agreed well with that of the observation. Three observed paths (Rita, Mimie and WINNIE) and a hypothetical path (Rita2) were chosen as the selective hurricane paths according to their positions relative to Tianjin. The sensitivity of Tianjin storm surge to the four paths was investigated using the validated storm surge simulation system. Three groups of experiments were done. In group one, the models were forced by the wind field and air pressure; in group two and three the models were forced by the wind only and the air pressure only respectively. In the experiments, the hurricane moved with a fixed speed and an intensity of 50 year return period. The simulation results show that path of the type Rita2 is the easiest to cause storm surge disaster in Tianjin, and the effect of air pressure forcing is most evident for path of the type Rita in Tianjin storm surge process. The above conclusions were analyzed through the evolution of the wind fields and the air pressure distributions. Comparing the experiment results of Group one, two and three, it can be seen that the storm surge is mainly induced by the wind forcing and the nonlinear interaction between the effect of wind forcing and air pressure forcing on the storm surge tends to weaken the storm surge.

  13. Direct Surge Margin Control for Aeroengines Based on Improved SVR Machine and LQR Method

    Directory of Open Access Journals (Sweden)

    Haibo Zhang

    2013-01-01

    Full Text Available A novel scheme of high stability engine control (HISTEC on the basis of an improved linear quadratic regulator (ILQR, called direct surge margin control, is derived for super-maneuver flights. Direct surge margin control, which is different from conventional control scheme, puts surge margin into the engine closed-loop system and takes surge margin as controlled variable directly. In this way, direct surge margin control can exploit potential performance of engine more effectively with a decrease of engine stability margin which usually happened in super-maneuver flights. For conquering the difficulty that aeroengine surge margin is undetectable, an approach based on improved support vector regression (SVR machine is proposed to construct a surge margin prediction model. The surge margin modeling contains two parts: a baseline model under no inlet distortion states and the calculation for surge margin loss under supermaneuvering flight conditions. The previous one is developed using neural network method, the inputs of which are selected by a weighted feature selection algorithm. Considering the hysteresis between pilot input and angle of attack output, an online scrolling window least square support vector regression (LSSVR method is employed to firstly estimate inlet distortion index and further compute surge margin loss via some empirical look-up tables.

  14. Assessment of Spatial Distribution and Submerged Scope for Storm Surge in the Pearl River Delta Region

    Institute of Scientific and Technical Information of China (English)

    LI Kuo; LI Guo-sheng

    2011-01-01

    The aim of this study was to explore the spatial distribution and submerged scope for storm surge in the Pearl River Delta (PRD) region.Based on the data of storm surges in the PRD region in the past 30 years, the return periods of 12 tide-gauge stations for storm surges were calculated separately with the methods of Gumbel and Pearson-iii.The data of another six tide-gauge stations in Guangdong Coast was quoted to depict the overall features of storm surges in Guangdong.Using least-square method, the spatial distribution models of storm surges in different retum periods were established to reveal the distribution rule of the set-up values of storm surges.The spatial distribution curves of storm surges in different retum periods in the PRD Region were drawn up based on the models and the terrain of Guangdong Coast.According to the curves, the extreme set-up values of storm surges in 1 000,100, 10 a return periods were determined on each spot of Guangdong Coast.Applying the spatial analysis technology of ArcGIS, with the topography data of the PRD Region, the submerged scopes of flood caused by storm surge in 1 000, 100, 10 a return periods were drawn up.The loss caused by storm surges was estimated.Results showed that the storm surges and the topography of PRD region jointly led to the serious flood in the PRD region.This assessment would be useful for the planning and design department to make decision and provide government scientific basis for storm surge prediction, coastal engineering designing and the prevention of storm surge disaster.

  15. Surges of outlet glaciers from the Drangajökull ice cap, northwest Iceland

    Science.gov (United States)

    Brynjólfsson, Skafti; Schomacker, Anders; Korsgaard, Niels J.; Ingólfsson, Ólafur

    2016-09-01

    Surface elevation and volume changes of the Drangajökull surge-type glaciers, Reykjarfjarðarjökull and Leirufjarðarjökull, were studied by comparing digital elevation models that pre-date and post-date their most recent surges. Annual glacier-frontal measurements were used to estimate average ice velocities during the last surge of the glaciers. The observations show a distinct ice discharge, most of which was from the upper reservoir areas, down to the receiving areas during the surges. The surface draw-down in the reservoir areas was usually 10-30 m during the surges, while the thickening of the receiving areas was significantly more variable, on the order of 10-120 m. Despite a negative geodetic net mass balance derived from the digital elevation models, the reservoir areas have been gaining mass since the surge terminations. This surface thickening along with considerable ablation of the receiving areas will most likely return the glacier surface profiles to the pre-surge stage. Our results indicate that (a) greatest surface thinning in the upper reservoir areas of Drangajökull rather than proximal to the equilibrium line during Vatnajökull surges and (b) development of Drangajökull surges that resembles Svalbard surge-type glaciers rather than Vatnajökull surge-type glaciers. The contrasting surge characteristics could be explained by differences in glacier geometry, topography and substratum of the Drangajökull and Vatnajökull surge-type glaciers.

  16. Confined vortices in flow machinery

    Science.gov (United States)

    Escudier, Marcel

    After noting such basic aspects of vortex flows as the concepts of supercritical and subcritical flow and vortex breakdown, swirling flow behavior in various practical devices is discussed. The devices in question encompass swirl-stabilized combustion in industrial combustion chambers, fluidic vortex amplifiers that may be used as large scale valves, turbomachine outlets that can efficiently divert axial throughflow in a tangential direction, 'cyclone' separators, turbine draft tube surge phenomena, and the Ranque-Hilsch refrigeration tube.

  17. Surge currents and voltages at the low voltage power mains during lightning strike to a GSM tower

    Energy Technology Data Exchange (ETDEWEB)

    Markowska, Renata [Bialystok Technical University (Poland)], E-mail: remark@pb.edu.pl

    2007-07-01

    The paper presents the results of numerical calculations of lightning surge currents and voltages in the low voltage power mains system connected to a free standing GSM base station. Direct lightning strike to GSM tower was studied. The analysis concerned the current that flows to the transformer station through AC power mains, the potential difference between the grounding systems of the GSM and the transformer stations and the voltage differences between phase and PE conductors of the power mains underground cable at both the GSM and the transformer sides. The calculations were performed using a numerical program based on the electromagnetic field theory and the method of moments. (author)

  18. 砂沟滴灌技术参数模型%Model for estimating technical parameters of sand furrow irrigation

    Institute of Scientific and Technical Information of China (English)

    赵伟霞; 张振华; 蔡焕杰; 单志杰

    2009-01-01

    Based on the analysis of the soil infiltration rule of the Sand Furrow Irrigation (SFI), a model for estimating the technical parameters for SFI is established according to the water-balance principle. These technical parameters are the ditch width and height, the permeable boundary height, and the emitter discharge rate. The experiments about the constant-head well infiltration and the Philip model are used to estimate the soil infiltration capacity. Based on the technical parameters calculated by this model, the experiments about the SFI are carried out to verify the model's feasibility. The factors affecting the model's accuracy are also analyzed. The results indicate that the model has the high precision to design the technical parameters for the SFI.The soil water sorption and soil water transmissivity are the function of the time in the two-dimensional constant-head well infiltration. The changing water depth and wetted perimeter are other factors affecting the model' s accuracy.%在分析砂沟滴灌土壤入渗规律的基础上,根据水量平衡原理建立了求解砂沟滴灌技术参数(沟宽、沟高、透水边壁高度、滴头流量)的模型,并将恒定水头积水入渗试验和Philip模型用于求解模型中的土壤入渗性能.以该模型计算的技术参数为基础,通过砂沟滴灌试验验证了模型的可行性,并对影响模型精度的因素做出了分析.试验结果表明,该模型能够较精确地设计砂沟滴灌技术参数.二维恒定水头积水入渗试验中,土壤吸渗率和渗透率是灌水时间的函数,砂沟滴灌中变化的积水深度和湿周是影响模型精度的另一个因素.

  19. Experimental Hydro-Mechanical Characterization of Full Load Pressure Surge in Francis Turbines

    Science.gov (United States)

    Müller, A.; Favrel, A.; Landry, C.; Yamamoto, K.; Avellan, F.

    2017-04-01

    Full load pressure surge limits the operating range of hydro-electric generating units by causing significant power output swings and by compromising the safety of the plant. It appears during the off-design operation of hydraulic machines, which is increasingly required to regulate the broad integration of volatile renewable energy sources into the existing power network. The underlying causes and governing physical mechanisms of this instability were investigated in the frame of a large European research project and this paper documents the main findings from two experimental campaigns on a reduced scale model of a Francis turbine. The multi-phase flow in the draft tube is characterized by Particle Image Velocimetry, Laser Doppler Velocimetry and high-speed visualizations, along with synchronized measurements of the relevant hydro-mechanical quantities. The final result is a comprehensive overview of how the unsteady draft tube flow and the mechanical torque on the runner shaft behave during one mean period of the pressure oscillation, thus defining the unstable fluid-structure interaction responsible for the power swings. A discussion of the root cause is initiated, based on the state of the art. Finally, the latest results will enable a validation of recent RANS flow simulations used for determining the key parameters of hydro-acoustic stability models.

  20. Vulnerability of Coastal Communities from Storm Surge and Flood Disasters.

    Science.gov (United States)

    Bathi, Jejal Reddy; Das, Himangshu S

    2016-02-19

    Disasters in the form of coastal storms and hurricanes can be very destructive. Preparing for anticipated effects of such disasters can help reduce the public health and economic burden. Identifying vulnerable population groups can help prioritize resources for the most needed communities. This paper presents a quantitative framework for vulnerability measurement that incorporates both socioeconomic and flood inundation vulnerability. The approach is demonstrated for three coastal communities in Mississippi with census tracts being the study unit. The vulnerability results are illustrated as thematic maps for easy usage by planners and emergency responders to assist in prioritizing their actions to vulnerable populations during storm surge and flood disasters.

  1. Two parametric tropical cyclone models for storm surge modeling

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-li

    2010-01-01

    In this paper,the two parametric tropical cyclone models for storm surge modeling are further developed.The analytical expressions of tangential and radial velocity distribution are derived from the governing momentum equations,based on the general symmetric pressure distribution proposed by Holland and Fujita.On the basis of the data of several tropical cyclones that occurred in East China Ocean,the shape parameter in pressure model is estimated.Finally,the Fred cyclone(typhoon 199417)is calculated,and comparisons of measured and calculated air pressures and wind speed are presented.

  2. High Resolution Hurricane Storm Surge and Inundation Modeling (Invited)

    Science.gov (United States)

    Luettich, R.; Westerink, J. J.

    2010-12-01

    Coastal counties are home to nearly 60% of the U.S. population and industry that accounts for over 16 million jobs and 10% of the U.S. annual gross domestic product. However, these areas are susceptible to some of the most destructive forces in nature, including tsunamis, floods, and severe storm-related hazards. Since 1900, tropical cyclones making landfall on the US Gulf of Mexico Coast have caused more than 9,000 deaths; nearly 2,000 deaths have occurred during the past half century. Tropical cyclone-related adjusted, annualized losses in the US have risen from 1.3 billion from 1949-1989, to 10.1 billion from 1990-1995, and $35.8 billion per year for the period 2001-2005. The risk associated with living and doing business in the coastal areas that are most susceptible to tropical cyclones is exacerbated by rising sea level and changes in the characteristics of severe storms associated with global climate change. In the five years since hurricane Katrina devastated the northern Gulf of Mexico Coast, considerable progress has been made in the development and utilization of high resolution coupled storm surge and wave models. Recent progress will be presented with the ADCIRC + SWAN storm surge and wave models. These tightly coupled models use a common unstructured grid in the horizontal that is capable of covering large areas while also providing high resolution (i.e., base resolution down to 20m plus smaller subgrid scale features such as sea walls and levees) in areas that are subject to surge and inundation. Hydrodynamic friction and overland winds are adjusted to account for local land cover. The models scale extremely well on modern high performance computers allowing rapid turnaround on large numbers of compute cores. The models have been adopted for FEMA National Flood Insurance Program studies, hurricane protection system design and risk analysis, and quasi-operational forecast systems for several regions of the country. They are also being evaluated as

  3. Coastal Flooding Hazards due to storm surges and subsidence

    DEFF Research Database (Denmark)

    Sørensen, Carlo; Knudsen, Per; Andersen, Ole B.

    Flooding hazard and risk mapping are major topics in low-lying coastal areas before even considering the adverse effects of sea level rise (SLR) due to climate change. While permanent inundation may be a prevalent issue, more often floods related to extreme events (storm surges) have the largest...... damage potential.Challenges are amplified in some areas due to subsidence from natural and/or anthropogenic causes. Subsidence of even a few mm/y may over time greatly impair the safety against flooding of coastal communities and must be accounted for in order to accomplish the economically most viable...

  4. The Early-Warning System for incoming storm surge and tide in the Republic of Mauritius

    Science.gov (United States)

    Bogaard, Tom; de Lima Rego, Joao; Vatvani, Deepak; Virasami, Renganaden; Verlaan, Martin

    2016-04-01

    The Republic of Mauritius (ROM) is a group of islands in the South West of the Indian Ocean, consisting of the main islands of Mauritius, Rodrigues and Agalega and the archipelago of Saint Brandon. The ROM is particularly vulnerable to the adverse effects of climate change, especially in the coastal zone, where a convergence of accelerating sea level rise and increasing intensity of tropical cyclones is expected to result in considerable economic loss, humanitarian stresses, and environmental degradation. Storm surges and swell waves are expected to be aggravated through sea level rise and climate change effects on weather patterns. Adaptation to increased vulnerability requires a re-evaluation of existing preparedness measures. The focus of this project is on more effective preparedness and issuing of alerts developing a fully-automated Early-Warning System for incoming storm surge and tide, together with the Mauritius Meteorological Services and the National Disaster Risk Reduction and Management Centre (NDRRMC), such that coastal communities in Mauritius, Rodrigues and Agalega Islands are able to evacuate timely and safely in case of predicted extreme water levels. The Mauritius Early-Warning System for storm surge and tide was implemented using software from Deltares' Open-Source and free software Community. A set of five depth-averaged Delft3D-FLOW hydrodynamic models are run every six-hours with a forecast horizon of three days, simulating water levels along the coast of the three main islands. Two regional models of horizontal resolution 5km force the three detailed models of 500m resolution; all models are forced at the surface by the 0.25° NOAA/GFS meteorological forecasts. In addition, our Wind-Enhancement Scheme is used to blend detailed cyclone track bulletin's info with the larger-scale Numerical Weather Predictions. Measured data is retrieved near real-time from available Automatic Weather Stations. All these workflows are managed by the operational

  5. Simulation of Storm Surge and Wave Due to Typhoon Isewan (5915)

    Institute of Scientific and Technical Information of China (English)

    Jin-Hee YUK; Kyeong Ok KIM; Han Soo LEE; Byung Ho CHOI

    2015-01-01

    An integrally coupled wave-tide-surge model was developed and then applied to the simulation of the wave-typhoon surge for the typhoon Isewan (typhoon Vera (5915)), which is the strongest typhoon that has struck Japan and caused incalculable damage. An integrally coupled tide-surge-wave model using identical and homogeneous meshes in an unstructured grid system was used to correctly resolve the physics of wave-circulation interaction in both models. All model components were validated independently. The storm surge and wave properties such as the surge height, the significant wave height, wave period and direction were reproduced reasonably under the meteorological forcing, which was reprocessed to be close to the observations. The resulting modeling system can be used extensively for the prediction of the storm surge and waves and the usual barotropic forecast.

  6. Effectiveness of installing two pairs of distribution surge arresters in parallel

    Energy Technology Data Exchange (ETDEWEB)

    Sugimoto, Hitoshi; Asakawa, Akira; Yokoyama, Shigeru [Central Research Institute of Electric Power Industry (Japan); Nakada, Kazuo [Hokurika Electric Power Co. (Japan)

    1999-07-01

    Lightning strokes with a large amount of energy sometimes occur on the Sea of Japan coast in winter. Winter lightning often damages overhead power distribution lines, in particular, those supplying power to high structures located in mountainous areas. We have investigated that the ratio of surge arrester outages with respect to all damaged installations on such power distribution lines is largest at approximately 50%. We have examined the effectiveness of installing two pairs of surge arresters in parallel on a single pole as a method for preventing distribution surge arrester outages experimentally. We have clarified that to install surge arresters in parallel is effective in reducing the energy absorbed by surge arresters if these surge arresters have almost the same discharge voltage and voltage-current characteristics. (author)

  7. Oxidative stress by peripheral blood mononuclear cells is increased in hypertensives with an extreme-dipper pattern and/or morning surge in blood pressure.

    Science.gov (United States)

    Maeda, Kensaku; Yasunari, Kenichi; Watanabe, Takanori; Nakamura, Munehiro

    2005-09-01

    Because oxidative stress and inflammation are known to play important roles in the pathogenesis of cardiovascular events that occur most frequently in the morning, we studied the association between reactive oxygen species (ROS) formation by polymorphonuclear leukocytes (PMNs) or mononuclear cells (MNCs) and morning blood pressure (BP) rhythm. A total of 31 hypertensives in whom ambulatory BP monitoring was performed participated in this study. They were first divided into three groups according to their nocturnal BP rhythm (non-dippers, dippers and extreme dippers), and then into two groups according to their morning BP change (surge-type and sustained-type). ROS formation by PMNs and MNCs was measured by gated flow cytometry. C-reactive protein and traditional risk factors such as age, gender, body mass index, hemoglobin A1c, and total cholesterol were also measured. ROS formation by MNCs was significantly increased in extreme dippers (vs. dippers, p<0.05, n=11) and in morning BP surge-type hypertensives (vs. sustained-type, p<0.05, n=13). In patients who were both extreme dippers and morning BP surge-types, ROS formation by MNCs was significantly higher than that in other groups. These results suggest that both extreme dippers and morning BP surge-type hypertensives may suffer increased ROS formation by MNCs, and that increased ROS formation by MNCs may underlie morning strokes.

  8. Effect of PSD on Acoustic Cavitation Surge in Inlet Pipe of Turbopump

    OpenAIRE

    吉田, 義樹; 藤原, 徹也; 南里, 秀明; Yoshida, Yoshiki; Fujiwara, Tetsuya; Nanri, Hideaki

    2013-01-01

    To investigate the effect of PSD on acoustic cavitation surge in turbopump, we conducted analyses with the resistance of PSD as a parameter. Consequently, we found that patterns of the acoustic cavitation surge were classified into three types by the value of the resistance. (1) First (the resistance of the PSD is smaller.), when the frequency of the inertial cavitation surge between the PSD and the turbopump coincides with the acoustic natural frequencies between the tank and the PSD, the ac...

  9. Characteristics and possibilities of software tool for metal-oxide surge arresters selection

    Directory of Open Access Journals (Sweden)

    Đorđević Dragan

    2012-01-01

    Full Text Available This paper presents a procedure for the selection of metal-oxide surge arresters based on the instructions given in the Siemens and ABB catalogues, respecting their differences and the characteristics and possibilities of the software tool. The software tool was developed during the preparation of a Master's thesis titled, 'Automation of Metal-Oxide Surge Arresters Selection'. An example is presented of the selection of metal-oxide surge arresters using the developed software tool.

  10. Mapping and Visualization of Storm-Surge Dynamics for Hurricane Katrina and Hurricane Rita

    Science.gov (United States)

    Gesch, Dean B.

    2009-01-01

    The damages caused by the storm surges from Hurricane Katrina and Hurricane Rita were significant and occurred over broad areas. Storm-surge maps are among the most useful geospatial datasets for hurricane recovery, impact assessments, and mitigation planning for future storms. Surveyed high-water marks were used to generate a maximum storm-surge surface for Hurricane Katrina extending from eastern Louisiana to Mobile Bay, Alabama. The interpolated surface was intersected with high-resolution lidar elevation data covering the study area to produce a highly detailed digital storm-surge inundation map. The storm-surge dataset and related data are available for display and query in a Web-based viewer application. A unique water-level dataset from a network of portable pressure sensors deployed in the days just prior to Hurricane Rita's landfall captured the hurricane's storm surge. The recorded sensor data provided water-level measurements with a very high temporal resolution at surveyed point locations. The resulting dataset was used to generate a time series of storm-surge surfaces that documents the surge dynamics in a new, spatially explicit way. The temporal information contained in the multiple storm-surge surfaces can be visualized in a number of ways to portray how the surge interacted with and was affected by land surface features. Spatially explicit storm-surge products can be useful for a variety of hurricane impact assessments, especially studies of wetland and land changes where knowledge of the extent and magnitude of storm-surge flooding is critical.

  11. The Genesis of Tropical Cyclone Bilis (2000) Associated with Cross-equatorial Surges

    Institute of Scientific and Technical Information of China (English)

    XU Yamei

    2011-01-01

    The purpose of this paper is to explore how a tropical cyclone forms from a pre-existing large-scale depression which has been observed and associated with cross-equatorial surges in the western North Pacific. Tropical cyclone Bilis (2000) was selected as the case to study. The research data used are from the results of the non-hydrostatic mesoscale model (MM5), which has successfully simulated the transformation of a pre-existing weak large-scale tropical depression into a strong tropical storm. The scale separation technique is used to separate the synoptic-scale and sub-synoptic-scale fields from the model output fields. The scale-separated fields show that the pre-existing synoptic-scale tropical depression and the subsynoptic scale tropical cyclone formed later were different scale systems from beginning to end. It is also shown that the pre-existing synoptic-scale tropical depression did not contract to become the tropical cyclone. A series of weak, sub-synoptic-scale low and high pressure systems appeared and disappeared in the synopticscale depression, with one of the low systems near the center of the synoptic-scale depression having deepened to become the tropical cyclone. The roles of the synoptic-scale flow and the sub-synoptic scale disturbances in the formation of the tropical cyclone are investigated by diagnoses of the scale-separated vertical vorticity equation. The results show that the early development of the sub-synoptic scale vortex was fundamentally dependent on the strengthening synoptic-scale environmental depression. The depression was strengthened by cross-equatorial surges, which increased the convergence of the synoptic-scale depression at low levels and triggered the formation of the tropical cyclone.

  12. The Genesis of Tropical Cyclone Bilis(2000) Associated with Cross-equatorial Surges

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The purpose of this paper is to explore how a tropical cyclone forms from a pre-existing large-scale depression which has been observed and associated with cross-equatorial surges in the western North Pacific. Tropical cyclone Bilis(2000) was selected as the case to study.The research data used are from the results of the non-hydrostatic mesoscale model(MM5),which has successfully simulated the transformation of a pre-existing weak large-scale tropical depression into a strong tropical storm.The scale separation technique is used to separate the synoptic-scale and sub-synoptic-scale fields from the model output fields. The scale-separated fields show that the pre-existing synoptic-scale tropical depression and the subsynoptic scale tropical cyclone formed later were different scale systems from beginning to end.It is also shown that the pre-existing synoptic-scale tropical depression did not contract to become the tropical cyclone. A series of weak,sub-synoptic-scale low and high pressure systems appeared and disappeared in the synopticscale depression,with one of the low systems near the center of the synoptic-scale depression having deepened to become the tropical cyclone. The roles of the synoptic-scale flow and the sub-synoptic scale disturbances in the formation of the tropical cyclone are investigated by diagnoses of the scale-separated vertical vorticity equation.The results show that the early development of the sub-synoptic scale vortex was fundamentally dependent on the strengthening synoptic-scale environmental depression.The depression was strengthened by cross-equatorial surges,which increased the convergence of the synoptic-scale depression at low levels and triggered the formation of the tropical cyclone.

  13. A Comparison of Ensemble Kalman Filters for Storm Surge Assimilation

    KAUST Repository

    Altaf, Muhammad

    2014-08-01

    This study evaluates and compares the performances of several variants of the popular ensembleKalman filter for the assimilation of storm surge data with the advanced circulation (ADCIRC) model. Using meteorological data from Hurricane Ike to force the ADCIRC model on a domain including the Gulf ofMexico coastline, the authors implement and compare the standard stochastic ensembleKalman filter (EnKF) and three deterministic square root EnKFs: the singular evolutive interpolated Kalman (SEIK) filter, the ensemble transform Kalman filter (ETKF), and the ensemble adjustment Kalman filter (EAKF). Covariance inflation and localization are implemented in all of these filters. The results from twin experiments suggest that the square root ensemble filters could lead to very comparable performances with appropriate tuning of inflation and localization, suggesting that practical implementation details are at least as important as the choice of the square root ensemble filter itself. These filters also perform reasonably well with a relatively small ensemble size, whereas the stochastic EnKF requires larger ensemble sizes to provide similar accuracy for forecasts of storm surge.

  14. New technology and tool prepared for communication against storm surges.

    Science.gov (United States)

    Letkiewicz, Beata

    2010-05-01

    The aim of the presentation is description of the new technology and tool prepared for communication, information and issue of warnings against storm surges. The Maritime Branch of the Institute of Meteorology and Water Management is responsible for preparing the forecast as warning, where the end users are Government Officials and Public. The Maritime Branch carry out the project "Strengthening the administrative capacity in order to improve the management of Polish coastal zone environment" (supported by a grant from Norway through the Norwegian Financial Mechanism). The expected final result of the project is web site www.baltyk.pogodynka.pl. One of the activities of the project is - set up of information website www.baltyk.pogodynka.pl, giving public access to the complied data. Information on web site: - meta data - marine data (on-line measurement: sea level, water temperature, salinity, oxygen concentration); - data bases of mathematical model outputs - forecast data (sea level, currents); - ice conditions of the Baltic Sea, - instructions, information materials with information of polish coastal zone. The aim of set up of the portal is development of communication between users of the system, exchange of the knowledge of marine environment and natural hazards such as storm surges, improving the ability of the region in the scope of the data management about the sea environment and the coastal zone.

  15. Blunting post-meal glucose surges in people with diabetes

    Institute of Scientific and Technical Information of China (English)

    Elsamma; Chacko

    2016-01-01

    Worldwide, the morbidity and mortality associated with non-communicable diseases have been climbing steadily- with costs aggressively keeping pace. This letter highlights a decidedly low-cost way to address the challenges posed by diabetes. High levels of postprandial blood glucose are disproportionately linked to much of the microvascular damage which, in the end, leads to macrovascular complications and organ failures. Systematically controlling post-meal glucose surges is a critical element of overall glycemic management indiabetes. Diet, exercise and medications form a triad of variables that individuals engaged in diabetes selfmanagement may manipulate to achieve their targeted glucose levels. As a rule, diabetes patients in developing countries as well as those living in the pockets of poverty in the western world cannot afford special diets, medications, glucometers and supplies, lab tests and office visits. Exercise is the one option that is readily accessible to all. Decades of research in laboratory settings, viewed holistically, have established that light to moderate aerobic exercise for up to 60 min starting 30 min after the first bite into a meal can blunt the ensuing glucose surge effectively. Moderate resistance exercise, moderate endurance exercise or a combination of the two, practiced post-meal has also been found to improve many cardio-metabolic markers: Glucose, high density lipoprotein, triglycerides, and markers of oxidative stress. On the other hand, pre-breakfast exercise and high-intensity exercise in general have been decidedly counterproductive.

  16. Surge protective device response to steep front transient in low voltage circuit

    Energy Technology Data Exchange (ETDEWEB)

    Marcuz, J.; Binczak, S.; Bilbault, J.M. [Universite de Bourgogne, Dijon (France)], Emails: jerome.marcuz@ laposte.net, stbinc@u-bourgogne.fr, bilbault@u-bourgogne.fr; Girard, F. [ADEE Electronic, Pont de Pany (France)

    2007-07-01

    Surge propagation on cables of electrical or data lines leads to a major protection problem as the number of equipment based on solid-state circuits or microprocessors increases. Sub-microsecond components of real surge waveform has to be taken into account for a proper protection even in the case of surges caused by indirect lightning effects. The response of a model of transient voltage suppressor diode based surge protection device (SPD) to fast front transient is analytically studied, then compared to simulations, including the lines connected to the SPD and to the protected equipment. (author)

  17. Vulnerability assessment of storm surges in the coastal area of Guangdong Province

    Directory of Open Access Journals (Sweden)

    K. Li

    2011-07-01

    Full Text Available Being bordered by the South China Sea and with long coastline, the coastal zone of Guangdong Province is often under severe risk of storm surges, as one of a few regions in China which is seriously threatened by storm surges. This article systematically analyzes the vulnerability factors of storm surges in the coastal area of Guangdong (from Yangjing to Shanwei. Five vulnerability assessment indicators of hazard-bearing bodies are proposed, which are social economic index, land use index, eco-environmental index, coastal construction index, and disaster-bearing capability index. Then storm surge vulnerability assessment index system in the coastal area of Guangdong is established. Additionally, the international general mode about coastal vulnerability assessment is improved, and the vulnerability evolution model of storm surges in the coastal area of Guangdong is constructed. Using ArcGIS, the vulnerability zoning map of storm surges in the study region is drawn. Results show that there is the highest degree of storm surge vulnerability in Zhuhai, Panyu, and Taishan; second in Zhongshan, Dongguan, Huiyang, and Haifeng; third in Jiangmen, Shanwei, Yangjiang, and Yangdong; fourth in Baoan, Kaiping, and Enping; and lowest in Guangzhou, Shunde, Shenzhen, and Longgang. This study on the risk of storm surges in these coastal cities can guide the land use of coastal cities in the future, and provide scientific advice for the government to prevent and mitigate the storm surge disasters. It has important theoretical and practical significance.

  18. Regional frequency analysis of extreme storm surges along the French coast

    Directory of Open Access Journals (Sweden)

    L. Bardet

    2011-06-01

    Full Text Available A good knowledge of extreme storm surges is necessary to ensure protection against flood. In this paper we introduce a methodology to determine time series of skew surges in France as well as a statistical approach for estimating extreme storm surges. With the aim to cope with the outlier issue in surge series, a regional frequency analysis has been carried out for the surges along the Atlantic coast and the Channel coast. This methodology is not the current approach used to estimate extreme surges in France. First results showed that the extreme events identified as outliers in at-site analyses do not appear to be outliers any more in the regional empirical distribution. Indeed the regional distribution presents a curve to the top with these extreme events that a mixed exponential distribution seems to recreate. Thus, the regional approach appears to be more reliable for some sites than at-site analyses. A fast comparison at a given site showed surge estimates with the regional approach and a mixed exponential distribution are higher than surge estimates with an at-site fitting. In the case of Brest, the 1000-yr return surge is 167 cm in height with the regional approach instead of 126 cm with an at-site analysis.

  19. Dynamics of surge-type glaciers in West Kunlun Shan, Northwestern Tibet

    Science.gov (United States)

    Yasuda, Takatoshi; Furuya, Masato

    2015-11-01

    Here we examine 31 glaciers in the West Kunlun Shan of the northwestern Tibetan Plateau and identify 9 as surge type. The method is based on satellite synthetic aperture radar and Landsat optical images, the former going back to 1992, the latter to 1972. To identify surge-type glaciers, we consider temporal changes in velocity, changes in glacier terminus position, propagation of a surge bulge, presence of looped and/or contoured medial moraines, and extensive crevassing. Other than the nine surge-type glaciers, we identify two that have likely surged, and six that may be surge type. But no glacier surges more than once during the observation period, meaning that the recurrence interval exceeds 42 years. In addition, we examine the evolution of the surface velocities at two surging glaciers with the unprecedented temporal resolution of down to 11 days over ˜7 years. The results show clear seasonal modulations by as much as ˜200% in early winter against those in early summer. This seasonal modulation in surface velocity suggests the presence of surface meltwater that reroutes through the englacial and subglacial drainage systems. Thus, our findings suggest that the hydrological processes originating in the surface meltwater play an important role in maintaining the yearlong active surging phase.

  20. The Anti-surge Capacity of the Surge Arresters for Information System%信息系统避雷器的抗浪涌能力

    Institute of Scientific and Technical Information of China (English)

    谭克勤

    2001-01-01

    The paper describes the basic characteristics about lightning over-voltage, the technology measures of anti-lightning, and the usage and classification of surge arresters. The paper forcus on the Anti-surge capacity of the various surge arresters.%阐述了雷电过电压的基本特性及防雷技术措施,避雷器的用途和分类,重点论述了各种信息系统避雷器的抗浪涌能力。

  1. Stability analysis of a run-of-river diversion hydropower plant with surge tank and spillway in the head pond.

    Science.gov (United States)

    Sarasúa, José Ignacio; Elías, Paz; Martínez-Lucas, Guillermo; Pérez-Díaz, Juan Ignacio; Wilhelmi, José Román; Sánchez, José Ángel

    2014-01-01

    Run-of-river hydropower plants usually lack significant storage capacity; therefore, the more adequate control strategy would consist of keeping a constant water level at the intake pond in order to harness the maximum amount of energy from the river flow or to reduce the surface flooded in the head pond. In this paper, a standard PI control system of a run-of-river diversion hydropower plant with surge tank and a spillway in the head pond that evacuates part of the river flow plant is studied. A stability analysis based on the Routh-Hurwitz criterion is carried out and a practical criterion for tuning the gains of the PI controller is proposed. Conclusions about the head pond and surge tank areas are drawn from the stability analysis. Finally, this criterion is applied to a real hydropower plant in design state; the importance of considering the spillway dimensions and turbine characteristic curves for adequate tuning of the controller gains is highlighted.

  2. Stability Analysis of a Run-of-River Diversion Hydropower Plant with Surge Tank and Spillway in the Head Pond

    Directory of Open Access Journals (Sweden)

    José Ignacio Sarasúa

    2014-01-01

    Full Text Available Run-of-river hydropower plants usually lack significant storage capacity; therefore, the more adequate control strategy would consist of keeping a constant water level at the intake pond in order to harness the maximum amount of energy from the river flow or to reduce the surface flooded in the head pond. In this paper, a standard PI control system of a run-of-river diversion hydropower plant with surge tank and a spillway in the head pond that evacuates part of the river flow plant is studied. A stability analysis based on the Routh-Hurwitz criterion is carried out and a practical criterion for tuning the gains of the PI controller is proposed. Conclusions about the head pond and surge tank areas are drawn from the stability analysis. Finally, this criterion is applied to a real hydropower plant in design state; the importance of considering the spillway dimensions and turbine characteristic curves for adequate tuning of the controller gains is highlighted.

  3. The "Ram Effect": A "Non-Classical" Mechanism for Inducing LH Surges in Sheep.

    Science.gov (United States)

    Fabre-Nys, Claude; Chanvallon, Audrey; Dupont, Joëlle; Lardic, Lionel; Lomet, Didier; Martinet, Stéphanie; Scaramuzzi, Rex J

    2016-01-01

    During spring sheep do not normally ovulate but exposure to a ram can induce ovulation. In some ewes an LH surge is induced immediately after exposure to a ram thus raising questions about the control of this precocious LH surge. Our first aim was to determine the plasma concentrations of oestradiol (E2) E2 in anoestrous ewes before and after the "ram effect" in ewes that had a "precocious" LH surge (starting within 6 hours), a "normal" surge (between 6 and 28h) and "late» surge (not detected by 56h). In another experiment we tested if a small increase in circulating E2 could induce an LH surge in anoestrus ewes. The concentration of E2 significantly was not different at the time of ram introduction among ewes with the three types of LH surge. "Precocious" LH surges were not preceded by a large increase in E2 unlike "normal" surges and small elevations of circulating E2 alone were unable to induce LH surges. These results show that the "precocious" LH surge was not the result of E2 positive feedback. Our second aim was to test if noradrenaline (NA) is involved in the LH response to the "ram effect". Using double labelling for Fos and tyrosine hydroxylase (TH) we showed that exposure of anoestrous ewes to a ram induced a higher density of cells positive for both in the A1 nucleus and the Locus Coeruleus complex compared to unstimulated controls. Finally, the administration by retrodialysis into the preoptic area, of NA increased the proportion of ewes with an LH response to ram odor whereas treatment with the α1 antagonist Prazosin decreased the LH pulse frequency and amplitude induced by a sexually active ram. Collectively these results suggest that in anoestrous ewes NA is involved in ram-induced LH secretion as observed in other induced ovulators.

  4. Zinc Oxide Surge Arresters and HVDC 125kV-upgrade 500kV Converter Stations

    Science.gov (United States)

    Shirakawa, Shingo; Kobayashi, Takayuki; Matsushita, Yoshinao; Sakai, Takehisa; Suzuki, Hironori; Ozaki, Yuzo

    Gapless Metal (Zinc) Oxide Surge Arresters for a.c. systems contribute to the insulation co-ordination based on the suppression of lightning surges and switching surges. These gapless metal oxide surge arresters using ZnO elements are effective to HVDC systems. This paper describes basic characteristics of ZnO (zinc oxide) elements for d.c. systems and applications of gapless surge arresters to HVDC 125kV frequency converters, HVDC 250kV, upgrade HVDC 500kV converter stations, and HVDC 500kV cables of Japan through the experience of developments and applications of gapless metal oxide surge arresters.

  5. Hybrid simulation of metal oxide surge-arrester thermal behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Huang, L.; Raghuveer, M.R. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Electrical and Computer Engineering

    1996-01-01

    A finite-difference-based technique for simulating the thermal behaviour of a metal oxide surge arrester (MOSA) was described. The improved hybrid thermal modelling technique was claimed to accurately represent heat-transfer modes. Fin theory was used to represent arrester sheds. The proposed model, which relies on simple measurements at the arrester terminals, yields the temporal variation of temperature in a MOSA in both the axial and radial direction. The thermal behaviour of a MOSA under steady-state and transient conditions can be simulated using such a model under different environmental conditions. The accuracy of the modelling technique was demonstrated experimentally by measurements conducted on an arrester. 15 refs., 7 figs.

  6. Designs for surge immunity in critical electronic facilities

    Science.gov (United States)

    Roberts, Edward F., Jr.

    1991-01-01

    In recent years, Federal Aviation Administration (FAA) embarked on a program replacing older tube type electronic equipment with newer solid state equipment. This replacement program dramatically increased the susceptibility of the FAA's facilities to lightning related damages. The proposal is presented of techniques which may be employed to lessen the susceptibility of new FAA electronic facility designs to failures resulting from lightning related surges and transients as well as direct strikes. The general concept espoused is one of a consistent system approach employing both perimeter and internal protection. It compares the technique presently employed to reduce electronic noise with other techniques which reduce noise while lowering susceptibility to lightning related damage. It is anticipated that these techniques will be employed in the design of an Air Traffic Control Tower in a high isokeraunic area. This facility would be subjected to rigorous monitoring over a multi-year period to provide quantitative data hopefully supporting the advantage of this design.

  7. Designs for surge immunity in critical electronic facilities

    Science.gov (United States)

    Roberts, Edward F., Jr.

    1991-08-01

    In recent years, Federal Aviation Administration (FAA) embarked on a program replacing older tube type electronic equipment with newer solid state equipment. This replacement program dramatically increased the susceptibility of the FAA's facilities to lightning related damages. The proposal is presented of techniques which may be employed to lessen the susceptibility of new FAA electronic facility designs to failures resulting from lightning related surges and transients as well as direct strikes. The general concept espoused is one of a consistent system approach employing both perimeter and internal protection. It compares the technique presently employed to reduce electronic noise with other techniques which reduce noise while lowering susceptibility to lightning related damage. It is anticipated that these techniques will be employed in the design of an Air Traffic Control Tower in a high isokeraunic area. This facility would be subjected to rigorous monitoring over a multi-year period to provide quantitative data hopefully supporting the advantage of this design.

  8. SAPS onset timing during substorms and the westward traveling surge

    Science.gov (United States)

    Mishin, Evgeny, V.

    2016-07-01

    We present multispacecraft observations in the magnetosphere and conjugate ionosphere of the onset time of subauroral polarization streams (SAPS) and tens of keV ring current injections on the duskside in three individual substorms. This is probably the first unequivocal determination of the substorm SAPS onset timing. The time lag between the SAPS and substorm onsets is much shorter than the gradient-curvature drift time of ˜10 keV ions in the plasmasphere. It seemingly depends on the propagation time of substorm-injected plasma from the dipolarization onset region to the plasmasphere, as well as on the SAPS position. These observations suggest that fast onset SAPS and ring current injections are causally related to the two-loop system of the westward traveling surge.

  9. Recent Trends of Technology of Zinc-Oxide Surge Arrester for Electric Power System

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.S.; Kim, K.U.; Cho, H.G. [Korea Electrotechnology Research Institute (Korea); Park, T.G. [Changwon National University (Korea); Park, S.H. [KEPCO (Korea)

    1999-05-01

    Metal-oxide surge arresters were developed in the late 1970s, and were immediately recognized as significant breakthrough in over-voltage protection of power system. Work was continued throughout the world on the design, development and application of metal-oxide surge arresters. (author). 6 refs., 1 fig., 6 tabs.

  10. Validating the calculated reliability and availability in Dutch storm surge barriers (and other infrastructural works)

    NARCIS (Netherlands)

    Kleijn van Willigen, G.K.; Meerveld, H. van

    2016-01-01

    The reliability and availability of the Dutch storm surge barriers are calculated by probabilistic risk assessment and various underlying risk analysis methods. These calculations, however, focus on the numerical probability of the storm surge barrier functioning adequately, and the implementation o

  11. Role of exogenous estrogen in initiation of estrus and induction of an LH surge

    Science.gov (United States)

    Among cattle the LH surge that causes ovulation occurs shortly after the onset of a spontaneous estrus. In addition an injection of 100 'g of GnRH can induce an LH surge capable of inducing ovulation. We hypothesized that different preovulatory estradiol profiles would result in different ovulator...

  12. Extreme storm surges: a comparative study of frequency analysis approaches

    Directory of Open Access Journals (Sweden)

    Y. Hamdi

    2013-11-01

    Full Text Available In France, nuclear facilities were designed to very low probabilities of failure. Nevertheless, exceptional climatic events have given rise to surges much larger than observations (outliers and had clearly illustrated the potential to underestimate the extreme water levels calculated with the current statistical methods. The objective of the present work is to conduct a comparative study of three approaches including the Annual Maxima (AM, the Peaks-Over Threshold (POT and the r-Largest Order Statistics (r-LOS. These methods are illustrated in a real analysis case study. All the data sets were screened for outliers. Non-parametric tests for randomness, homogeneity and stationarity of time series were used. The shape and scale parameters stability plots, the mean excess residual life plot and the stability of the standard errors of return levels were used to select optimal thresholds and r values for the POT and r-LOS method, respectively. The comparison of methods was based on: (i the uncertainty degrees, (ii the adequacy criteria and tests and (iii the visual inspection. It was found that the r-LOS and POT methods have reduced the uncertainty on the distributions parameters and return level estimates and have systematically shown values of the 100 and 500 yr return levels smaller than those estimated with the AM method. Results have also shown that none of the compared methods has allowed a good fitting at the right tail of the distribution in the presence of outliers. As a perspective, the use of historical information was proposed in order to increase the representativity of outliers in data sets. Findings are of practical relevance not only to nuclear energy operators in France, for applications in storm surge hazard analysis and flood management, but also for the optimal planning and design of facilities to withstand extreme environmental conditions, with an appropriate level of risk.

  13. Extreme storm surges: a comparative study of frequency analysis approaches

    Science.gov (United States)

    Hamdi, Y.; Bardet, L.; Duluc, C.-M.; Rebour, V.

    2014-08-01

    In France, nuclear facilities were designed around very low probabilities of failure. Nevertheless, some extreme climatic events have given rise to exceptional observed surges (outliers) much larger than other observations, and have clearly illustrated the potential to underestimate the extreme water levels calculated with the current statistical methods. The objective of the present work is to conduct a comparative study of three approaches to extreme value analysis, including the annual maxima (AM), the peaks-over-threshold (POT) and the r-largest order statistics (r-LOS). These methods are illustrated in a real analysis case study. All data sets were screened for outliers. Non-parametric tests for randomness, homogeneity and stationarity of time series were used. The shape and scale parameter stability plots, the mean excess residual life plot and the stability of the standard errors of return levels were used to select optimal thresholds and r values for the POT and r-LOS method, respectively. The comparison of methods was based on (i) the uncertainty degrees, (ii) the adequacy criteria and tests, and (iii) the visual inspection. It was found that the r-LOS and POT methods have reduced the uncertainty on the distribution parameters and return level estimates and have systematically shown values of the 100 and 500-year return levels smaller than those estimated with the AM method. Results have also shown that none of the compared methods has allowed a good fit at the right tail of the distribution in the presence of outliers. As a perspective, the use of historical information was proposed in order to increase the representativeness of outliers in data sets. Findings are of practical relevance, not only to nuclear energy operators in France, for applications in storm surge hazard analysis and flood management, but also for the optimal planning and design of facilities to withstand extreme environmental conditions, with an appropriate level of risk.

  14. Directional Storm Surge in Enclosed Seas: The Red Sea, the Adriatic, and Venice

    Directory of Open Access Journals (Sweden)

    Carl Drews

    2015-05-01

    Full Text Available Storm surge is dependent on wind direction, with maximum surge heights occurring when strong winds blow onshore. It is less obvious what happens when a port city is situated at the end of a long narrow gulf, like Venice at the northwestern end of the Adriatic Sea. Does the narrow marine approach to the port city limit the dangerous wind direction to a span of only a few degrees? This modeling study shows that the response in surge height to wind direction is a sinusoidal curve for port cities at the end of a long inlet, as well as for cities exposed along a straight coastline. Surge height depends on the cosine of the angle between the wind direction and the major axis of the narrow gulf. There is no special protection from storm surge afforded by a narrow ocean-going approach to a port city.

  15. Quantification of Sediment Transport During Glacier Surges and its Impact on Landform Architecture

    DEFF Research Database (Denmark)

    Kjær, Kurt H.; Schomacker, Anders; Korsgaard, Niels Jákup

    Eos Trans. AGU, 89(53), Fall Meet. Suppl., Abstract C23A-0580 Multi-temporal DEMs (Digital Elevation Models) of glaciers and ice streams have successfully been used for extraction of changes in ice volume over time. In this study, we analysed DEMs of the Brúarjökull glacier forefield (Iceland......) for 1945, prior to the last surge in 1964, and for 2003 in order to assess the effect of the surge on the sediment architecture in the forefield. The pre- and post-surge DEMs allow direct quantification of the sediment volumes that were re-distributed in the forefield by the surging ice mass in 1964...... margin, where the impact of four surges is evident. Thus, the landscape at Brúarjökull is a product of multiple generations of superimposed landforms associated with extensive sediment transport through subglacial deformation....

  16. Determining Storm Surge Return Periods: The Use of Evidence of Historic Events

    DEFF Research Database (Denmark)

    Madsen, Kristine S.; Sørensen, Carlo Sass; Schmith, Torben

    Storm surges are a major concern for many coastal communities, and rising levels of surges is a key concern in relation to climate change. The sea level of a statistical 100-year or 1000-year storm surge event and similar statistical measures are used for spatial planning and emergency preparedness....... These statistics are very sensitive to the assessments of past events, and to future sea level change. The probability of a major storm surge from the Baltic Sea hitting the Copenhagen metropolitan area is officially determined by the Danish Coastal Authority based on tide gauge records. We have a long history......, but with the revised statistics using historic evidence, much larger events can be expected. Further, we assess the very large impact of sea level rise on the storm surge statistics. As an example, according to the official statistics of southern Copenhagen, the flooding of a present day 100 year event...

  17. Multivariate extreme value analysis of storm surges in SCS on peak over threshold method

    Directory of Open Access Journals (Sweden)

    Y. Luo

    2015-11-01

    Full Text Available We use a novel statistical approach-MGPD to analyze the joint probability distribution of storm surge events at two sites and present a warning method for storm surges at two adjacent positions in Beibu Gulf, using the sufficiently long field data on surge levels at two sites. The methodology also develops the procedure of application of MGPD, which includes joint threshold and Monte Carlo simulation, to handle multivariate extreme values analysis. By comparing the simulation result with analytic solution, it is shown that the relative error of the Monte Carlo simulation is less than 8.6 %. By running MGPD model based on long data at Beihai and Dongfang, the simulated potential surge results can be employed in storm surge warnings of Beihai and joint extreme water level predictions of two sites.

  18. Magnetic fabric and remanent magnetization of pyroclastic surge deposits from Vulcano (Aeolian Islands, Italy)

    Science.gov (United States)

    Zanella, E.; De Astis, G.; Dellino, P.; Lanza, R.; La Volpe, L.

    1999-11-01

    Tufi di Grotte dei Rossi Inferiori are unwelded, fine-grained pyroclastic deposits of hydromagmatic origin emplaced between 21 and 11-8.6 ka at Vulcano (Aeolian Islands, Italy) by deposition through surges spreading laterally from inside the La Fossa caldera. In this study, the deposit's magnetic properties were investigated and interpreted in terms of eruptive and emplacement dynamics. Rock-magnetism data were supplemented by grain size and textural characteristic analyses as well as scanning electron microscope (SEM) investigations. Curie point measurements, isothermal remanent magnetization and microprobe analyses showed that magnetization is carried by low-Ti titanomagnetite. The size of the grains ranges from about 20 to 300 micrometres, their shape from equidimensional to highly elongated. The magnetic fabric is typical of fine-grained pyroclastics. Foliation is well developed and in most sites lineation is directed towards the source area of the La Fossa caldera. The remanent magnetization consists of two components whose blocking temperature spectra partially overlap. The direction of the low-temperature component is close to that of the axial dipole, and consistent with the palaeosecular variation curve for the Aeolian Islands. The high-temperature component is systematically shallowed and close to the direction of the magnetic lineation. The overall results suggest that the high-temperature component was acquired before, and the low-temperature component after, the actual deposition of grains. Immediately after eruption, the grains cooled and moved as free particles in the turbulent cloud during the expansion of the surge flows. Those particles with high blocking temperatures acquired a thermal remanence. They were then deposited and shear at the very base of the flow oriented them and imprinted the rock's fabric and high-temperature magnetization component. Volcanological and magnetic data suggest turbulent transportation and traction deposition of

  19. 果蝇长时程记忆缺陷型突变体的鉴定%Identifying Furrowed Mutant in Drosophila with Long-term Memory Deficience

    Institute of Scientific and Technical Information of China (English)

    王世清; 孙侃; 帅祎春; 王连章; 钟毅

    2012-01-01

    长时程记忆作为依赖蛋白合成的记忆组分,对于了解高等认知活动的分子机制有着重要意义.与此同时,细胞粘连分子作为影响突触可塑性的重要因子在学习与记忆研究领域也日益得到重视.为探索作用于长时程记忆的细胞粘连分子,利用P因子在果蝇基因组随机插入制造突变体,并通过大规模行为筛选得到了一个可能的长时程记忆突变体RUO.测序结果表明,突变体RUO的P因子位于果蝇中selectin超家族对应的furrowed同源基因功能片段和未知功能的CG1806基因编码片段之间,且更靠近furrowed片段.RT-PCR结果和互补遗传学实验均表明,突变体RUO主要影响furrowed基因的表达.为了进一步确认furrowed基因与长时程记忆的相关性,引入已知的furrowed基因突变体fw1.结果表明,fw1同样具有长时程记忆缺陷,同时具备正常的学习能力.荧光共聚焦扫描成像显示,该基因特异性的表达在果蝇大脑两个对称的未知神经元中.此项工作不仅证明了furrowed基因在果蝇长时程记忆中的重要作用,而且在解剖学上揭示了果蝇神经系统中可能参与长时程记忆形成的新的神经元.%Long-term memory related protein synthesis is a significant aspect for understanding of advanced cognitive behavior. Exploration of the relationship between long-term memory and adhesion molecules helped to link synaptic plasticity change with behavior modification. To discover novel adhesion molecules participating memory formation, we screened for defective long-term memory mutants in Drosophila of P-element inserted stocks, and obtained one defective mutant RUO. DNA sequencing and RT-PCR showed that the P-element in RUO mutant only disrupted the expression of the protein furrowed, an adhesion molecule of selectin superfamily. Both RUO mutant and an existed furrow mutant fw1 were observed defective for long-term memory in behavior experiments, but with normal aversive

  20. A new occurrence of the benthic amphipod Dyopedos monacanthus (Metzger, 1875 in the southern Baltic Sea - the first record in the Słupsk Furrow

    Directory of Open Access Journals (Sweden)

    Diana Dziaduch

    2007-03-01

    Full Text Available The paper reports on the occurrence of the epibenthic amphipod Dyopedos monacanthus (Metzger, 1875 in the Baltic Sea. This species belongs to the family Dulichiidae and is found in the North Atlantic and European coastal waters from northern Norway to the English Channel and the Danish Straits. Some 50 years ago, only a few individuals of D. monacanthus were occasionally sighted inthe western Baltic (the Arkona and Bornholm Basins. In summer 2006, unusual amphipod specimens were noticed at five deep-waterstations over the Slupsk Furrow. This was the first time that D. monacanthus was observed in that area,which is currently the easternmost limit of the species' range in the Baltic Sea.

  1. A new dynamical index for classification of cold surge types over East Asia

    Science.gov (United States)

    Park, Tae-Won; Ho, Chang-Hoi; Jeong, Jee-Hoon; Heo, Jin-Woo; Deng, Yi

    2015-11-01

    The cold surges over East Asia can be classified into wave-train type and blocking type according to their dynamic origins. In the present study, two dynamic indices are proposed to objectively identify cold surge types using potential temperature ( θ) on the dynamic tropopause at 2-potential vorticity units (2-PVU) surface. The two indices are designed to represent primary characteristics of the two types of cold surge. The wave-train index ( WI) is defined as a difference of anomalous θ on the 2-PVU surface between the western North Pacific and northeast China, which captures a southward (northward) intrusion of cold (warm) air mass related to the trough-ridge pattern. The blocking index ( BI) is defined as a difference of anomalous θ between the subarctic region and northeast China, which indicates air mass overturning related to a reversal of the usual meridional θ gradient commonly observed in the occurrence of blocking type cold surge. Composite analyses based on the distribution of the WI and BI clearly demonstrate the dynamic evolutions of corresponding cold surge types. The wave-train cold surge is associated with a southeastward expansion of the Siberian High and northerly wind near surface, which is caused by growing baroclinic waves. During the blocking cold surge, a geopotential height dipole indicating the subarctic blocking and deepening of East Asian coastal trough induces a southward expansion of the Siberian High and northeasterly wind. Compared to the wave-train type, the blocking cold surge exhibits a longer duration and stronger intensity. In the new framework of these dynamic indices, we can detect a third type of cold surge when both the wave-train and the blocking occur together. In addition, we can exclude the events that do not have the essential features of the upper tropospheric disturbances or the subarctic anticyclonic circulation, which are responsible for cold surge occurrence, using the new indices.

  2. Global reconstructed daily surge levels from the 20th Century Reanalysis (1871-2010)

    Science.gov (United States)

    Cid, Alba; Camus, Paula; Castanedo, Sonia; Méndez, Fernando J.; Medina, Raúl

    2017-01-01

    Studying the effect of global patterns of wind and pressure gradients on the sea level variation (storm surge) is a key issue in understanding the recent climate change effect on the dynamical state of the ocean. The analysis of the spatial and temporal variability of storm surges from observations is a difficult task to accomplish since observations are not homogeneous in time, scarce in space, and moreover, their temporal coverage is limited. A recent global surge database developed by AVISO (DAC, Dynamic Atmospheric Correction) fulfilled the lack of data in terms of spatial coverage, but not regarding time extent, since it only includes the last two decades (1992-2014). In this work, we use the 20th Century Reanalysis V2 (20CR), which spans the years 1871 to 2010, to statistically reconstruct daily maximum surge levels at a global scale. A multivariate linear regression model is fitted between daily mean ERA-interim sea level pressure fields and daily maximum surge levels from DAC. Following, the statistical model is used to reconstruct daily surges using mean sea level pressure fields from 20CR. The verification of the statistical model shows good agreements between DAC levels and the reconstructed surge levels from the 20CR. The validation of the reconstructed surge with tide gauges, distributed throughout the domain, shows good accuracy both in terms of high correlations and small errors. A time series comparison is also depicted at specific tide gauges for the beginning of the 20th century, showing a high concordance. Therefore, this work provides to the scientific community, a daily database of maximum surge levels; which correspond to an extension of the DAC database, from 1871 to 2010. This database can be used to improve the knowledge on historical storm surge conditions, allowing the study of their temporal and spatial variability.

  3. Spatial distribution of erosion and deposition during a glacier surge: Brúarjökull, Iceland

    Science.gov (United States)

    Korsgaard, Niels J.; Schomacker, Anders; Benediktsson, Ívar Örn; Larsen, Nicolaj K.; Ingólfsson, Ólafur; Kjær, Kurt H.

    2015-12-01

    Time-series of digital elevation models (DEMs) of the forefield of the Brúarjökull surge-type glacier in Iceland were used to quantify the volume of material that was mobilized by the 1963-1964 surge. The DEMs were produced by stereophotogrammetry on aerial photographs from before the surge (1961) and after (1988 and 2003). The analysis was performed on two DEMs of Difference (DoDs), i.e., a 1961-2003 DoD documenting the impact of the surge and a 1988-2003 DoD documenting the post-surge modification of the juvenile surging glacier landsystem. Combined with a digital geomorphological map, the DoDs allow us to quantify the impact of the surge on a landsystem scale down to individual landforms. A total of 34.2 ± 11.3 × 106 m3 of material was mobilized in the 30.7-km2 study area as a result of the most recent surge event. Of these, 17.4 ± 6.6 × 106 m3 of the material were eroded and 16.8 ± 4.7 × 106 m3 were deposited. More than half of the deposited volume was ice-cored landforms. This study demonstrates that although the total mobilized mass volume is high, the net volume gain of ice and sediment deposited as landforms in the forefield caused by the surge is low. Furthermore, deposition of new dead-ice from the 1963-1964 surge constitutes as much as 64% of the volume gain in the forefield. The 1988-2003 DoD is used to quantify the melt-out of this dead-ice and other paraglacial modification of the recently deglaciated forefield of Brúarjökull.

  4. Storm surge and wave simulations in the Gulf of Mexico using a consistent drag relation for atmospheric and storm surge models

    Directory of Open Access Journals (Sweden)

    D. Vatvani

    2012-07-01

    Full Text Available To simulate winds and water levels, numerical weather prediction (NWP and storm surge models generally use the traditional bulk relation for wind stress, which is characterized by a wind drag coefficient. A still commonly used drag coefficient in those models, some of them were developed in the past, is based on a relation, according to which the magnitude of the coefficient is either constant or increases monotonically with increasing surface wind speed (Bender, 2007; Kim et al., 2008; Kohno and Higaki, 2006. The NWP and surge models are often tuned independently from each other in order to obtain good results. Observations have indicated that the magnitude of the drag coefficient levels off at a wind speed of about 30 m s−1, and then decreases with further increase of the wind speed. Above a wind speed of approximately 30 m s−1, the stress above the air-sea interface starts to saturate. To represent the reducing and levelling off of the drag coefficient, the original Charnock drag formulation has been extended with a correction term.

    In line with the above, the Delft3D storm surge model is tested using both Charnock's and improved Makin's wind drag parameterization to evaluate the improvements on the storm surge model results, with and without inclusion of the wave effects. The effect of waves on storm surge is included by simultaneously simulating waves with the SWAN model on identical model grids in a coupled mode. However, the results presented here will focus on the storm surge results that include the wave effects.

    The runs were carried out in the Gulf of Mexico for Katrina and Ivan hurricane events. The storm surge model was initially forced with H*wind data (Powell et al., 2010 to test the effect of the Makin's wind drag parameterization on the storm surge model separately. The computed wind, water levels and waves are subsequently compared with observation data. Based on the good

  5. The Brazos River (Texas) Sequence Shows Significant Cooling in the Waning Stages of the Tsunami Surges Caused by the Chicxulub Impact

    Science.gov (United States)

    Smit, J.; Vellekoop, J.

    2013-05-01

    The Brazos river K-Pg sequences are among the best preserved and studied in the world, yet any interpretation remains highly controversial. Most researchers, however, agree that the coarse clastic deposits are the direct result of a train of Chicxulub impact triggered tsunami surges. Alternative interpretations such as low stand deposits or (super) storm deposits lack sedimentological support. The entire impact related deposit starts with a strong ground shaking from the impact-induced earthquake, disintegrating unconsolidated uppermost Maastrichtian muds, and opening 0.5m deep and 5 m long fissures filled with spherule-rich debris. The disintegrated debris has been taken up in a coarse mass-flow, just underlying the first coarse tsunami deposit containing impact spherules from Chicxulub. One to four distinct tsunami surges follow the basal surge, each leaving a graded coarse to medium sand deposit assembled from coarse debris strewn on the local seafloor such as glauconitic pellets, fish-debris and near coastal foraminifers. The medium-grained sand layers are typically cross-bedded in linguoid and linguoid-climbing current-ripple sets, indicating a dominant S to SE seaward directed flow. Such climbing ripple-sets are found in most tsunami deposits in NE Mexico. These climbing ripples indicate an extremely high suspension load, quickly settling on the seafloor in the waning tsunami surge backflow-currents. Occasionally, the climbing ripple directions are reversed, showing the upflow direction of the incoming tsunami surge. Such linguoid climbing ripple sets have often been mistaken for storm-wave induced hummocky cross-bedding (HCS), leading to storm-deposit hypotheses. The final phase of settling out of the tsunami surges, may be re-suspension due to impact-triggered storms in the Gulf, is represented by continuously graded, very fine-grained sand to silt deposit. This is initially a hard 10 cm thick silty lime-mudstone layer with plant debris, grading into drab

  6. Monitoreo del glaciar horcones inferior y sus termokarst, antes y durante el surge de 2003-2006: Andes centrales argentinos

    Directory of Open Access Journals (Sweden)

    María Gabriela Lenzano

    2012-12-01

    Full Text Available En el presente trabajo se expone el monitoreo de termokarts glaciarios y su relación e interacción con los eventos surges ocurridos en el glaciar cubierto Horcones Inferior (GHI. Este glaciar se encuentra ubicado a los 32º 41'S y 69º 57'W, al pie de la pared sur del C° Aconcagua, Parque Provincial Aconcagua, en la Provincia de Mendoza, Argentina. El estudio fue llevado a cabo a través de la implementación de métodos indirectos de detección utilizando imágenes de los sensores Landsat y Aster durante el período 1997-2006. En el Glaciar Horcones Inferior "GHI", la superficie ocupada por los termokarst alcanza valores que varían entre el 4.3% y el 0% de la superficie total del glaciar, al finalizar un evento de surge. Las velocidades registradas en la superficie del glaciar cubierto arrojaron valores promedios entre 0.4 y 12 m/día. La metodología aplicada, con imágenes satelitales históricas, representa una herramienta fundamental para separar períodos de flujo glaciario catastróficos y no catastróficos.This work analyses the temporal evolution of thermokarst and their relationship to the surges in a reconstituted debris covered glacier. The glacier Horcones Inferior is located at Lat 32º 41' S and Long 69º 57' W in the Provincial Park Aconcagua, Mendoza, Argentina, on the foot of the Aconcagua massif. The study and monitoring of the thermokarst was carried out applying indirect methods using Landsat and Aster images from 1997-2006. Detected percentages of thermokarst, in relation to the total glacial area, showed that they varied between 4.3% to 0% at the end of the surge event. The registered speeds of the glacier -on the glacial surface- reached averages of between 0.4 and 12 m/d. This methodology, with historical images from archives, represents a fundamental tool to separate catastrophic and non-catastrophic glacial flow periods.

  7. Reconnaissance Level Studies on a Storm Surge Barrier for Flood Risk Reduction in the Houston-Galveston Bay

    NARCIS (Netherlands)

    Jonkman, S.N.; Mooyaart, L.F.; Van Ledden, M.; Stoeten, K.J.; De Vries, P.A.L.; Lendering, K.T.; Van der Toorn, A.; Willems, A.

    2014-01-01

    The Houston - Galveston area is at significant risk from hurricane induced storm surges. This paper summarizes ongoing studies on flood risk reduction for the region. Firstly, based on a simplified probabilistic hurricane surge model , the return periods of surges within the bay have been estimated.

  8. A preliminary study on the intensity of cold wave storm surges of Laizhou Bay

    Science.gov (United States)

    Li, Xue; Dong, Sheng

    2016-12-01

    Dike failure and marine losses are quite prominent in Laizhou Bay during the period of cold wave storm surges because of its open coastline to the north and flat topography. In order to evaluate the intensity of cold wave storm surge, the hindcast of marine elements induced by cold waves in Laizhou Bay from 1985 to 2004 is conducted using a cold wave storm surge-wave coupled model and the joint return period of extreme water level, concomitant wave height, and concomitant wind speed are calculated. A new criterion of cold wave storm surge intensity based on such studies is developed. Considering the frequency of cold wave, this paper introduces a Poisson trivariate compound reconstruction model to calculate the joint return period, which is closer to the reality. By using the newly defined cold wave storm surge intensity, the `cold wave grade' in meteorology can better describe the severity of cold wave storm surges and the warning level is well corresponding to different intensities of cold wave storm surges. Therefore, it provides a proper guidance to marine hydrological analysis, disaster prevention and marine structure design in Laizhou Bay.

  9. Study on the storm surges induced by cold waves in the Northern East China Sea

    Science.gov (United States)

    Mo, Dongxue; Hou, Yijun; Li, Jian; Liu, Yahao

    2016-08-01

    Cold wave, a kind of severe weather system, can bring strong wind and induce significant sea level rise to the Northern East China Sea. Based on CFSR data, the study shows the monthly distributions of invaded days and the spatiotemporal distributions of cold-wave wind direction and wind speed. A three-dimensional numerical model (ROMS) was developed to study storm surges induced by cold waves. The role of wind direction, wind speed, wind duration, extratropical cyclone and tide-surge interaction is investigated by conducting different sensitivity experiments. The results indicate that storm surges mainly happen at the coasts perpendicular to the wind directions. Surge range and time lag are related to the geometry of the basin and the continental shelf. The response of the sea-level fluctuations to cold wave indicates that there is a positive correlation between crests and wind speed, a negative correlation between troughs and wind speed, but no obvious correlations to wind duration. Coupled weather cold waves, which yield a larger range and a multi-peak structure of surges, can be classified according to cold wave tracks and extratropical cyclones. The tide-surge interaction has an obvious and different effect on the magnitudes and phases of storm surges for different tidal stages.

  10. CFD simulation of pressure and discharge surge in Francis turbine at off-design conditions

    Science.gov (United States)

    Chirkov, D.; Avdyushenko, A.; Panov, L.; Bannikov, D.; Cherny, S.; Skorospelov, V.; Pylev, I.

    2012-11-01

    A hybrid 1D-3D CFD model is developed for the numerical simulation of pressure and discharge surge in hydraulic power plants. The most essential part - the turbine itself - is simulated directly using 3D unsteady equations of turbulent motion of fluid-vapor mixture, while the rest of the hydraulic system is simulated in frames of 1D hydro-acoustic model. Thus the model accounts for the main factors responsible for excitation and propagation of pressure and discharge waves in hydraulic power plant. Boundary conditions at penstock inlet and draft tube outlet are discussed in detail. Then simulations of dynamic behavior at part load and full load operating points are performed. It is shown that the numerical model is able to capture self-excited oscillations in full load conditions. The influence of penstock length and flow structure behind the runner are investigated. The presented approach seems to be a promising tool for prediction and investigation the dynamic behavior in hydraulic power plants.

  11. Slab entrainment and surge dynamics of the 2015 Valleé de la Sionne avalanches

    Science.gov (United States)

    Köhler, Anselm; McElwaine, Jim; Sovilla, Betty

    2016-04-01

    On 3 February 2015 five avalanches were artificially released at the Valleé de la Sionne test site in the west of Switzerland. The dense parts of the avalanches were tracked by the GEODAR Mark 2 radar system at 111 Hz framerate with 0.75 m down slope resolution. The data show that these avalanche contain several internal surges and that the avalanche front is repeatedly overtaken by some of these surges. We show that these surges exist on different scale. While the major surges originates from secondary triggered slab releases and occur all over the avalanche. The minor surges are only found in the energetic part of a well developed powder snow avalanche. The mass of the major surges can be as huge as the initial released mass, this has a dramatic effect on the mass distribution inside the avalanche and effects the front velocity and run out. Furthermore, the secondary released snow slabs are an important entrainment mechanism and up to 50 percent of the mass entered the avalanche via slab entrainment. We analyse the dynamics of the leading edge and the minor surges in more detail using a simple one dimensional model with frictional resistance and quadratic velocity dependent drag. These models fit the data well for the start and middle of avalanche but cannot capture the slowing and overtaking of the minor surge. We find much higher friction coefficients to describe the surging. We propose that this data can only be explained by changes in the snow surface. These effects are not included in current models yet, but the data presented here will enable the development and verification of such models.

  12. The influence of coastal wetlands on hurricane surge in Corpus Christi, TX

    Science.gov (United States)

    Ferreira, C.; Irish, J. L.; Olivera, F.

    2010-12-01

    The State of Texas has historically faced hurricane-related damage episodes, with Ike being the most recent example. It is expected that, in the future, hurricanes will intensify due to climate change causing greater surges, while the attenuating effect of wetlands on storm surges will also be modified due to sea level rise changes in wetland vegetation type and spatial location. Numerical analysis of storm surges is an important instrument to predict and simulate flooding extent and magnitude in coastal areas. Most operational surge models account for the influence of wetlands and other vegetation by momentum loss due to friction at the bottom and by reduction of imposed wind stress. A coupled hydrodynamic model (ADCIRC) and wave model (SWAN) was employed, and wetlands were characterized using Manning’s n, surface canopy, and surface roughness. The wetlands parameters were developed from: 1) the National Land Cover Dataset (NLCD) 1992 and 2001; 2) the National Wetlands Inventory (NWI) 2001. The calibrated coupled model for two historical hurricanes, Bret and Beulah, was used to simulate the storm surge for each scenario. Preliminary results for the sensitivity analyses, for hurricane Bret, comparing the scenarios with parameters developed from NLCD and NWI datasets with four hypothetical scenarios considering very high and low Manning’s n and wind stress (surface canopy) values showed that, for areas inside Nueces Bay, the storm surge high could vary up to four times depending on the parameter selection, for areas inside Corpus Christi Bay, the storm surge high varied around three times and behind the barrier island the storm surge high variation was less than three times. This study is a first step for an evaluation of the impact that sea level rise, climate changed wetlands, wetlands restoration, land use change, and wetlands degradation have on hurricane related surge elevation and extent in the city of Corpus Christi.

  13. A global record of large storm surges and loss of life

    Science.gov (United States)

    Bouwer, Laurens; Jonkman, Sebastiaan

    2017-04-01

    Storm surges can cause very high numbers of loss of life (fatalities) in single events, and these events are expected to increase due to sea-level rise and increasing population in coastal zones. However, compared to fatalities from fresh water flooding, for storm surges these fatality numbers are not consistently recorded, and often neglected in scientific assessments. In order to assess the impacts of major coastal storm surge events at the global level, we have developed a record of these events and associated loss of life. Information was compiled from the EM-DAT database for the period 1900-2013, using the two key categories of "Tropical cyclone" and "Storm surge/coastal flood", complemented with other databases and sources of information, and records of observed surge levels. We find that globally, each year on average about 8,500 people are killed and 1.3 million people are affected by storm surges. The occurrence of very substantial loss of life (>10,000 persons) from single events has decreased over time, which is in contrast with the slight increasing trends in fatalities observed for fresh water flooding. Also, there is a consistent and strong decrease in event mortality, which is the fraction of the people exposed to surges that lose their life, for all global regions, except South-East Asia. Thus, reduction in vulnerability to loss of life over time plays a significant role in storm surge impacts. We also find that for the same coastal surge water level, mortality appears to have decreased over time, showing the robustness of this finding. This quantified decline can be attributed to risk reduction efforts over the last decades, including improved forecasting, early warning and evacuation, but also improved coastal protection. These results have important implications for assessment studies on current and projected future coastal flood risk, as historical mortality fractions may not be valid to assess impacts from future events.

  14. The evolution of a submarine landform record following recent and multiple surges of Tunabreen glacier, Svalbard

    Science.gov (United States)

    Flink, Anne Elina; Noormets, Riko; Kirchner, Nina; Benn, Douglas I.; Luckman, Adrian; Lovell, Harold

    2015-01-01

    This study focuses on the glacial landform record associated with recent surge events of Tunabreen - a calving tidewater glacier in Tempelfjorden, Spitsbergen. Submarine geomorphology and recent terminal fluctuations of Tunabreen's glacier front were studied using high-resolution multibeam-bathymetric data and a range of published and remote-sensing sources, including topographic maps, satellite images and aerial photographs. The retreat moraines in the inner part of Tempelfjorden have been correlated with glacier terminus positions during retreat from the 2004 surge maximum. Glacier surface velocity and ice-front positions derived from high-resolution TerraSAR-X satellite data show ice movements at the glacier front during minor advances of the front in winter when calving is suppressed. This suggests that the moraines have formed annually during quiescent phase winter advances. Tunabreen has experienced three surges since the Little Ice Age (LIA). This is in contrast with most Svalbard surging glaciers which have long quiescent phases and have typically only undergone one or two surges during this time. The landform record in Tempelfjorden is distinguished from previously studied glacier-surge landsystems by four, well-preserved sets of landform assemblages generated by the LIA advance and three subsequent surges, all of which partly modify earlier landform records. Based on the unique landform record in Tempelfjorden, a new conceptual landsystem model for frequently surging glaciers has been put forward improving our understanding of the dynamics of the surging glaciers and, most importantly, how they can be distinguished from the climatically-controlled glaciers in the geological record.

  15. Developing an early warning system for storm surge inundation in the Philippines

    Directory of Open Access Journals (Sweden)

    J. Tablazon

    2014-10-01

    Full Text Available A storm surge is the sudden rise of sea water generated by an approaching storm, over and above the astronomical tides. This event imposes a major threat in the Philippine coastal areas, as manifested by Typhoon Haiyan on 8 November 2013 where more than 6000 people lost their lives. It has become evident that the need to develop an early warning system for storm surges is of utmost importance. To provide forecasts of the possible storm surge heights of an approaching typhoon, the Nationwide Operational Assessment of Hazards under the Department of Science and Technology (DOST-Project NOAH simulated historical tropical cyclones that entered the Philippine Area of Responsibility. Bathymetric data, storm track, central atmospheric pressure, and maximum wind speed were used as parameters for the Japan Meteorological Agency Storm Surge Model. The researchers calculated the frequency distribution of maximum storm surge heights of all typhoons under a specific Public Storm Warning Signal (PSWS that passed through a particular coastal area. This determines the storm surge height corresponding to a given probability of occurrence. The storm surge heights from the model were added to the maximum astronomical tide data from WXTide software. The team then created maps of probable area inundation and flood levels of storm surges along coastal areas for a specific PSWS using the results of the frequency distribution. These maps were developed from the time series data of the storm tide at 10 min intervals of all observation points in the Philippines. This information will be beneficial in developing early warnings systems, static maps, disaster mitigation and preparedness plans, vulnerability assessments, risk-sensitive land use plans, shoreline defense efforts, and coastal protection measures. Moreover, these will support the local government units' mandate to raise public awareness, disseminate information about storm surge hazards, and implement

  16. Identification of storm surge events over the German Bight from atmospheric reanalysis and climate model data

    Science.gov (United States)

    Befort, D. J.; Fischer, M.; Leckebusch, G. C.; Ulbrich, U.; Ganske, A.; Rosenhagen, G.; Heinrich, H.

    2015-06-01

    A new procedure for the identification of storm surge situations for the German Bight is developed and applied to reanalysis and global climate model data. This method is based on the empirical approach for estimating storm surge heights using information about wind speed and wind direction. Here, we hypothesize that storm surge events are caused by high wind speeds from north-westerly direction in combination with a large-scale wind storm event affecting the North Sea region. The method is calibrated for ERA-40 data, using the data from the storm surge atlas for Cuxhaven. It is shown that using information of both wind speed and direction as well as large-scale wind storm events improves the identification of storm surge events. To estimate possible future changes of potential storm surge events, we apply the new identification approach to an ensemble of three transient climate change simulations performed with the ECHAM5/MPIOM model under A1B greenhouse gas scenario forcing. We find an increase in the total number of potential storm surge events of about 12 % [(2001-2100)-(1901-2000)], mainly based on changes of moderate events. Yearly numbers of storm surge relevant events show high interannual and decadal variability and only one of three simulations shows a statistical significant increase in the yearly number of potential storm surge events between 1900 and 2100. However, no changes in the maximum intensity and duration of all potential events is determined. Extreme value statistic analysis confirms no frequency change of the most severe events.

  17. Identification of storm surge events over the German Bight from atmospheric reanalysis and climate model data

    Directory of Open Access Journals (Sweden)

    D. J. Befort

    2015-06-01

    Full Text Available A new procedure for the identification of storm surge situations for the German Bight is developed and applied to reanalysis and global climate model data. This method is based on the empirical approach for estimating storm surge heights using information about wind speed and wind direction. Here, we hypothesize that storm surge events are caused by high wind speeds from north-westerly direction in combination with a large-scale wind storm event affecting the North Sea region. The method is calibrated for ERA-40 data, using the data from the storm surge atlas for Cuxhaven. It is shown that using information of both wind speed and direction as well as large-scale wind storm events improves the identification of storm surge events. To estimate possible future changes of potential storm surge events, we apply the new identification approach to an ensemble of three transient climate change simulations performed with the ECHAM5/MPIOM model under A1B greenhouse gas scenario forcing. We find an increase in the total number of potential storm surge events of about 12 % [(2001–2100–(1901–2000], mainly based on changes of moderate events. Yearly numbers of storm surge relevant events show high interannual and decadal variability and only one of three simulations shows a statistical significant increase in the yearly number of potential storm surge events between 1900 and 2100. However, no changes in the maximum intensity and duration of all potential events is determined. Extreme value statistic analysis confirms no frequency change of the most severe events.

  18. Surge Capacity of Hospitals in Emergencies and Disasters With a Preparedness Approach: A Systematic Review.

    Science.gov (United States)

    Sheikhbardsiri, Hojjat; Raeisi, Ahmad Reza; Nekoei-Moghadam, Mahmood; Rezaei, Fatemeh

    2017-03-07

    Surge capacity is one of the most important components of hospital preparedness for responding to emergencies and disasters. The ability to provide health and medical care during a sudden increase in the number of patients or victims of disasters is a main concern of hospitals. We aimed to perform a systematic review of hospital surge capacity in emergencies and disasters with a preparedness approach. A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The key words "surge," "surge capacity," "preparedness," "hospital emergency department," "hospital," "surge capability," "emergency," "hazard," "disaster," "catastrophe," "crisis," and "tragedy" were used in combination with the Boolean operators OR and AND. The Google Scholar, ISI Web of Science, Science Direct, PubMed, Scopus, Ovid, Pro Quest, and Wiley databases were searched. A total of 1008 articles were extracted and 17 articles were selected for final review of surge capacity based on the objective of the study. Seventeen studies (1 randomized controlled trial, 2 qualitative studies, and 14 cross-sectional studies) investigated the surge capacity of hospitals in emergencies and disasters to evaluate the best evidence to date. The results of selected articles indicated that there are various ways to increase the capacity of hospitals in 4 domains: staff, stuff, structure, and system. Surge capacity is a basic element of disaster preparedness programs. Results of the current study could help health field managers in hospitals to prepare for capacity-building based on surge capacity components to improve and promote hospital preparedness programs. (Disaster Med Public Health Preparedness. 2017;page 1 of 9).

  19. Switching surge overvoltages on a feeding system of a MAGLEV train; Jiki fujoshiki tetsudo no kidenkei ni okeru kaihei surge kaden`atsu

    Energy Technology Data Exchange (ETDEWEB)

    Muragishi, H. [Nippon Yusoki Co. Ltd., Kyoto (Japan); Nakamura, Y.; Muraoka, N.; Ametani, A. [Doshisha Univ., Kyoto (Japan)

    1997-04-20

    Discussions using simulations were given on surge overvoltages and earth fault surge overvoltage associated with operation of a section switchgear in a feeding system of a MAGLEV train. Results of the discussions may be summarized as follows: throw-in surge overvoltage caused by the section switchgear is about 25 kV at maximum on the coil and about 15 kV on the cable sheath. The coil overvoltage increases as the closer to 90 degrees the throw-in phase approaches, and the greater the power supply frequency increases. The cable sheath overvoltage, however, is not affected by these environments. Breaking surge overvoltage caused by the section switchgear reaches 115 kV on the coil and about the same value on the cable sheath when the breaking current is 50 A. Earth fault surge overvoltage due to cable fault is 24 kV at maximum on the coil, while it reaches 32 kV on the cable sheath. The cable sheath overvoltage depends largely on sheath installing conditions. These overvoltages can be suppressed sufficiently lower than insulation levels of each device by installing arresters. 17 refs., 18 figs.

  20. Time-frequency analysis of the Surge Onset in the Centrifugal Blower

    Directory of Open Access Journals (Sweden)

    Liskiewicz Grzegorz

    2015-09-01

    Full Text Available Time frequency analysis of the surge onset was performed in the centrifugal blower. A pressure signal was registered at the blower inlet, outlet and three locations at the impeller shroud. The time-frequency scalograms were obtained by means of the Continuous Wavelet Transform (CWT. The blower was found to successively operate in four different conditions: stable working condition, inlet recirculation, transient phase and deep surge. Scalograms revealed different spectral structures of aforementioned phases and suggest possible ways of detecting the surge predecessors.

  1. Association between the rate of the morning surge in blood pressure and cardiovascular events and stroke

    Institute of Scientific and Technical Information of China (English)

    LUO Yu; WANG Yan-li; WU Ying-biao; XU Yao; Geoffrey A.Head; Macgrathy Barry; LIANG Yu-lu

    2013-01-01

    Background The exaggerated surge in morning blood pressure (BP) that many patients experience upon awakening may be closely related to target organ damage and may be a predictor of cardiovascular complications.However,no previous studies have evaluated the rate of this surge independently of the evening period.It remains unclear whether the rate of increase experienced during the surge is a significant or independent determinant of cardiovascular events.Methods We randomly selected 340 ambulatory BP monitoring (ABPM) patients.All subjects without type 2 diabetes mellitus were divided into two groups:hypertensive group (n=170) and normotensive group (n=170).We analyzed ambulatory blood pressure recordings using a double logistic curve-fitting procedure to determine whether the magnitude of the surge in BP and heart rate (HR) in the morning is related to the level of BP in hypertensive individuals.We evaluated the association between the rate of the morning surge in systolic BP (SBP) and the incidence of myocardial infarction and stroke in normotensive and hypertensive subjects.Results Comparisons between hypertensive and normotensive subjects showed that the rates of the morning surges in SBP,mean BP (MBP),and diastolic BP (DBP) were greater in the hypertensive group (P <0.05) than in the normotensive group.The rate of morning surge in BP was found to be correlated with the daytime SBP (r=0.236,P <0.01),the difference between the day and night plateau (r=0.249,P <0.01),and the night SBP (r=-0.160,P <0.05),respectively.After controlling for age,sex,and mean systolic pressure within 24 hours (24 h SBP),the rate of morning surge in SBP was closely correlated with daytime SBP (r=0.463,P <0.001),night SBP (r=-0.173,P <0.05),and the difference between the day and night plateau (r=0.267,P <0.001).Logistic regression analysis revealed that the rate of morning surge in SBP was an independent determinant of myocardial infarction (OR=1.266,95% CI=1.153-1.389,P

  2. Smart Ultrasound Remote Guidance Experiment (SURGE) Preliminary Findings

    Science.gov (United States)

    Hurst, Victor; Dulchavsky, Scott; Garcia, Kathleen; Sargsyan, Ashot; Ebert, Doug

    2009-01-01

    To date, diagnostic quality ultrasound images were obtained aboard the International Space Station (ISS) using the ultrasound of the Human Research Facility (HRF) rack in the Laboratory module. Through the Advanced Diagnostic Ultrasound in Microgravity (ADUM) and the Braslet-M Occlusion Cuffs (BRASLET SDTO) studies, non-expert ultrasound operators aboard the ISS have performed cardiac, thoracic, abdominal, vascular, ocular, and musculoskeletal ultrasound assessments using remote guidance from ground-based ultrasound experts. With exploration class missions to the lunar and Martian surfaces on the horizon, crew medical officers will necessarily need to operate with greater autonomy given communication delays (round trip times of up to 5 seconds for the Moon and 90 minutes for Mars) and longer periods of communication blackouts (due to orbital constraints of communication assets). The SURGE project explored the feasibility and training requirements of having non-expert ultrasound operators perform autonomous ultrasound assessments in a simulated exploration mission outpost. The project aimed to identify experience, training, and human factors requirements for crew medical officers to perform autonomous ultrasonography. All of these aims pertained to the following risks from the NASA Bioastronautics Road Map: 1) Risk 18: Major Illness and Trauna; 2) Risk 20) Ambulatory Care; 3) Risk 22: Medical Informatics, Technologies, and Support Systems; and 4) Risk 23: Medical Skill Training and Maintenance.

  3. Nivmar: a storm surge forecasting system for Spanish waters

    Directory of Open Access Journals (Sweden)

    Enrique Álvarez Fanjul

    2001-07-01

    Full Text Available In this paper, a storm surge prediction system for the Spanish Waters is presented. The system, named Nivmar, is based on the ocean circulation Hamsom model and on the harmonical prediction of tides computed from data measured by the tide gauge network Redmar, managed by Puertos del Estado. Nivmar is executed twice a day, running Hamsom forced by meteorological fields derived from the INM (Instituto Nacional de Meteorología operational application of Hirlam atmospheric model. Data from Redmar tide gauges is used to to forecast the tidal elevations, to validate the system and to perform data assimilation, correcting systematic errors in the mean sea level due to physicals processes that are not included in the ocean model (i. e. steric height. The forecast horizon is 48 hours. In order to validate the system with measured data from Redmar a very stormy 5 months period was selected. Results from this test (November 95 to March 96 are presented. Data from this experiment shown that Nivmar is able to correctly predict sea level in the region. A simple data assimilation scheme for sea level is described and results from its application are studied. Finally, special focus is made in future plans and potential developments and applications of the system.

  4. Southeastern Regional Pediatric Disaster Surge Network: a public health partnership.

    Science.gov (United States)

    Ginter, Peter M; Rucks, Andrew C; Duncan, W Jack; Wingate, Martha S; Beeman, S Kenn; Reeves, Jane; West, Maury A

    2010-01-01

    In the event of a natural or man-made disaster involving large numbers of children, resources in the Southeastern U.S. are extremely limited. This article chronicles the efforts of the Alabama Department of Public Health, the Mississippi State Department of Health, and the South Central Center for Public Health Preparedness in conjunction with more than 40 organizations to develop a voluntary network of health-care providers, public health departments, volunteers, and emergency responders from Alabama, Florida, Louisiana, Mississippi, and Tennessee. The purpose of the Southeastern Regional Pediatric Disaster Surge Network (the Network) is to improve the pediatric preparedness response strategies of public health, emergency response, and pediatric providers in the event of large-scale emergencies or disasters that overwhelm local or state pediatric resources. The planning and development of the Network is proceeding through three general phases--information sharing, mutual goal setting and collective action, and long-term formal linkages. In Phase 1, critical planning tasks to be undertaken in the development of the Network were identified. In Phase 2, the agencies developed a draft operational handbook that served as the basis for a formal memorandum of understanding. In Phase 3, participants will engage in exercises and evaluations that will further identify and work out logistical and operational details.

  5. 冬小麦沟灌土壤水分动态和生长发育的试验研究%Experimental Study on the Soil Water Dynamics and Growth Effect of Winter Wheat in Furrow Irrigation Mode

    Institute of Scientific and Technical Information of China (English)

    高传昌; 汪顺生; 傅渝亮; 李兴敏

    2011-01-01

    在不同灌溉方式下进行冬小麦土壤水分动态、生长发育的对比试验研究.结果表明:拔节期以前,畦灌与沟灌的土壤水分与生长发育差异不大,拔节后期,随着灌水量的增加,其土壤水分与生长发育差异逐渐明显,沟灌土壤含水量整体较畦灌增幅达到11.6%;叶面积指数(LAI)以及地上干物质分别提高11.4%和39.73%,差异性明显,但株高整体不如畦灌;从产量方面,沟灌模式在整体节水40%条件下,产量平均提高7.66%,水分生产效率提高0.28 kg/m3.达到节水增产的统一.综合本试验数据,其中垄植沟灌配合3水沟灌为本次试验最佳分配方案.%This paper reported a study on the soil water dynamics and growth development of winter wheat under treatments of different furrow irrigations. The results showed that the soil water dynamics and growth development were similar under different irrigation treatments before the jointing stage. After the jointing stage,with the increasing of irrigation amount, the soil water content under furrow irrigation was 11. 6% higher than that under border irrigation,and both leaf area index (LAD and ground dry matter increased by 11.4%and 39. 73% under furrow irrigation than those under border irrigation, respectively. However, plant height was lower under furrow irrigation than those under border irrigation. Comparing with the flat irrigation mode, the irrigation amount saved by 40 %, the production increased by 7. 66%, and efficiency of water use increased by 0. 28 kg/m3 under furrow irrigation, which achieved the goals of water-saving and high yield Based on the data in this study, the best experiment scenario was the three times irrigation under the furrow irrigation and ridge planting.

  6. The Application of 3-D Numerical Simulation to Calculating the Waves in Surge Tanks%CFD在调压室涌浪水位模拟中的应用

    Institute of Scientific and Technical Information of China (English)

    刘飞; 杨建东; 李进平

    2011-01-01

    While a hydropower station is in its transition process, the unsteady flow in the tailrace surge tank has been simulated by using the method of CFD. In this paper, the surge wave and the bottom plate pressure difference are the focus of concern in the 3-D numerical simulation. Three turbulence models have been used to simulate the unsteady flow. We can illustrate the differences between the three turbulence models while they are used to simulate the transition process. Based on the advantage that the 3-D numerical simulation can capture the information of internal flow field, we are also able to explore the situation of free surface and flow regime in the surge tank through the entire wave process.%对某水电站的尾水隧洞及下游调压室过渡过程中的非恒定流流态进行三维数值模拟,着重观测调压室内涌浪波动及调压室内底板压差变化过程。采用3种湍流模型对下游调压室及尾水隧洞进行了模拟,将调压室涌浪波动过程与调压室底板压差变化过程的三维计算结果与物理模型实验、一维数值计算的相应结果予以对比分析,阐明了不同湍流模型对过渡过程模拟的影响。结合三维模拟能捕捉流场内部流态的优势,探讨了涌浪波动过程中调压室水面波动过程及水流流态。

  7. Esforços em ferramentas rompedoras de solo de semeadoras de plantio direto Loads in furrow opening tools for seeders on no-tillage systems

    Directory of Open Access Journals (Sweden)

    Renildo Luiz Mion

    2008-10-01

    Full Text Available A avaliação individual de mecanismos de abertura de sulco de semeadoras de plantio direto auxilia as empresas no dimensionamento de ferramentas rompedoras do solo, que buscam menor requerimento energético e a diminuição da área de solo mobilizado. Portanto, objetivou-se, neste trabalho, avaliar os esforços de cinco diferentes mecanismos de abertura de sulco de semeadoras de plantio direto, variando a carga vertical. O experimento foi instalado num solo classificado como Nitossolo Vermelho Distroférrico. O delineamento experimental utilizado foi o de blocos ao acaso, em esquema fatorial 5 x 4, constituídos dos seguintes fatores: cinco mecanismos de abertura de sulco (disco liso - DL, disco corrugado -DC, disco ondulado - DO, disco duplo - DD e haste sulcadora - F e quatro cargas verticais (750, 1500, 2250 e 3000 N. Para mensurar as forças nos tratamentos estudados foi utilizado um dinamômetro com sensibilidade nas direções horizontal, lateral, vertical. A avaliação mostrou que a interação entre mecanismos de abertura de sulco e carga vertical não foi significativa, entretanto os fatores foram significativos quando analisados individualmente. A haste promoveu a maior mobilização do solo com menor requerimento de esforço horizontal, atingindo as maiores profundidades de trabalho. O trabalho mostrou que a carga vertical influenciou a profundidade de trabalho dos mecanismos de abertura de sulco. Os mecanismos de abertura de sulco do tipo disco necessitam de maior força vertical para penetrar no solo.The individual evaluation of mechanisms for opening furrows to drop the seeds in a no-tillage seeders cultivation assists the companies in the sizing of opening tools of the ground, that search for minor energy petition and for diminishing the ground area mobilized. Therefore this work had the aim of evaluate the efforts of five different mechanisms of opening of ridge of seeding of direct plantation varyng the vertical load. The

  8. Lightning arrester models enabling highly accurate lightning surge analysis; Koseidona kaminari surge kaiseki wo kano ni suru hiraiki model

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, T. [Chubu Electric Power Co. Inc., Nagoya (Japan); Funabashi, T.; Hagiwara, T.; Watanabe, H. [Meidensha Corp., Tokyo (Japan)

    1998-12-28

    Introduced herein are a dynamic behavior model for lightning arresters designed for power stations and substations and a flashover model for a lightning arresting device designed for transmission, both developed by the author et al. The author et al base their zinc oxide type lightning arrester model on the conventional static V-I characteristics, and supplement them with difference in voltage between static and dynamic characteristics. The model is easily simulated using EMTP (Electromagnetic Transients Program) etc. There is good agreement between the results of calculation performed using this model and actually measured values. Lightning arresting devices for transmission have come into practical use, and their effectiveness is introduced on various occasions. For the proper application of such devices, an analysis model capable of faithfully describing the flashover characteristics of arcing horns installed in great numbers along transmission lines, and of lightning arresting devices for transmission, are required. The author et al have newly developed a flashover model for the devices and uses the model for the analysis of lightning surges. It is found that the actually measured values of discharge characteristics of lightning arresting devices for transmission agree well with the values calculated by use of the model. (NEDO)

  9. Multi-Output Artificial Neural Network for Storm Surge Prediction in North Carolina

    CERN Document Server

    Bezuglov, Anton; Santiago, Reinaldo

    2016-01-01

    During hurricane seasons, emergency managers and other decision makers need accurate and `on-time' information on potential storm surge impacts. Fully dynamical computer models, such as the ADCIRC tide, storm surge, and wind-wave model take several hours to complete a forecast when configured at high spatial resolution. Additionally, statically meaningful ensembles of high-resolution models (needed for uncertainty estimation) cannot easily be computed in near real-time. This paper discusses an artificial neural network model for storm surge prediction in North Carolina. The network model provides fast, real-time storm surge estimates at coastal locations in North Carolina. The paper studies the performance of the neural network model vs. other models on synthetic and real hurricane data.

  10. More Research Shows Big Surge in U.S. Opioid Use, Addictions

    Science.gov (United States)

    ... Research Shows Big Surge in U.S. Opioid Use, Addictions Report from major insurer shows more than 20 ... Health News on Health Disparities Opioid Abuse and Addiction Recent Health News Related MedlinePlus Health Topics Health ...

  11. Control of Surge in Centrifugal Compressors by Active Magnetic Bearings Theory and Implementation

    CERN Document Server

    Yoon, Se Young; Allaire, Paul E

    2013-01-01

    Control of Surge in Centrifugal Compressors by Active Magnetic Bearings sets out the fundamentals of integrating the active magnetic bearing (AMB) rotor suspension technology in compressor systems, and describes how this relatively new bearing technology can be employed in the active control of compressor surge. The authors provide a self-contained and comprehensive review of rotordynamics and the fundamentals of the AMB technology. The active stabilization of compressor surge employing AMBs in a machine is fully explored, from the modeling of the instability and the design of feedback controllers, to the implementation and experimental testing of the control algorithms in a specially-constructed, industrial-size centrifugal compression system. The results of these tests demonstrate the great potential of the new surge control method developed in this text. This book will be useful for engineers in industries that involve turbocompressors and magnetic bearings, as well as for researchers and graduate students...

  12. Sea, Lake, and Overland Surge from Hurricanes (SLOSH) Inundation for Categories 2 and 4

    Data.gov (United States)

    U.S. Environmental Protection Agency — The file geodatabase (fgdb) contains the Sea, Lake, and Overland Surge from Hurricanes (SLOSH) Maximum of Maximums (MOM) model for hurricane categories 2 and 4. The...

  13. Evaluation of Ferrite Chip Beads as Surge Current Limiters in Circuits with Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander

    2014-01-01

    Limiting resistors are currently required to be connected in series with tantalum capacitors to reduce the risk of surge current failures. However, application of limiting resistors decreases substantially the efficiency of the power supply systems. An ideal surge current limiting device should have a negligible resistance for DC currents and high resistance at frequencies corresponding to transients in tantalum capacitors. This work evaluates the possibility of using chip ferrite beads (FB) as such devices. Twelve types of small size FBs from three manufacturers were used to evaluate their robustness under soldering stresses and at high surge current spikes associated with transients in tantalum capacitors. Results show that FBs are capable to withstand current pulses that are substantially greater than the specified current limits. However, due to a sharp decrease of impedance with current, FBs do not reduce surge currents to the required level that can be achieved with regular resistors.

  14. Three-Dimensional Numerical Analysis of Compound Lining in Complex Underground Surge-Shaft Structure

    Directory of Open Access Journals (Sweden)

    Juntao Chen

    2015-01-01

    Full Text Available The mechanical behavior of lining structure of deep-embedded cylinder surge shaft with multifork tunnel is analyzed using three-dimensional nonlinear FEM. With the elastic-plastic constitutive relations of rock mass imported and the implicit bolt element and distributed concrete cracking model adopted, a computing method of complex surge shaft is presented for the simulation of underground excavations and concrete lining cracks. In order to reflect the interaction and initial gap between rock mass and concrete lining, a three-dimensional nonlinear interface element is adopted, which can take into account both the normal and tangential characteristics. By an actual engineering computation, the distortion characteristics and stress distribution rules of the dimensional multifork surge-shaft lining structure under different behavior are revealed. The results verify the rationality and feasibility of this computation model and method and provide a new idea and reference for the complex surge-shaft design and construction.

  15. nowCOAST's Map Service for NOAA NWS NHC Potential Storm Surge Flooding Map

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Map Information: This nowCOAST map service provides maps depicting the latest official NWS Potential Storm Surge Flooding Map for any significant landfalling...

  16. Global reconstructed daily storm surge levels from the 20th century reanalysis (1871-2010)

    Science.gov (United States)

    Cid, Alba; Camus, Paula; Castanedo, Sonia; Mendez, Fernando; Medina, Raul

    2015-04-01

    The study of global patterns of wind and pressure gradients, and more specifically, their effect on the sea level variation (storm surge), is a key issue in the understanding of recent climate changes. The local effect of storm surges on coastal areas (zones particularly vulnerable to climate variability and changes in sea level), is also of great interest in, for instance, flooding risk assessment. Studying the spatial and temporal variability of storm surges from observations is a difficult task to accomplish since observations are not homogeneous in time and scarce in space, and moreover, their temporal coverage is limited. The development of a global storm surge database (DAC, Dynamic Atmospheric Correction by Aviso, Carrère and Lyard, 2003) fulfils the lack of data in terms of spatial coverage, but not regarding time extent since it only includes last couple of decades (1992-2014). In this work, we propose the use of the 20CR ensemble (Compo et al., 2011) which spans from 1871 to 2010 to statistically reconstruct storm surge at a global scale and for a long period of time. Therefore, the temporal and spatial variability of storm surges can be fully studied and with much less effort than performing a dynamical downscaling. The statistical method chosen to carry out the reconstruction is based on multiple linear regression between an atmospheric predictor and the storm surge level at daily scale (Camus et al., 2014). The linear regression model is calibrated and validated using daily mean sea level pressure fields (and gradients) from the ERA-interim reanalysis and daily maxima surges from DAC. The obtained daily database of maximum daily surges has allowed us to estimate global trends at a centennial scale and analyse the effect of the changing climate on storm surges during the 20th century. Hence, this work improves the knowledge on historical storm-surge conditions and provides helpful information to the community concern on marine climate evolution and

  17. On the 'real' mass loss of some surging glaciers in the central Karakoram

    Science.gov (United States)

    Paul, Frank

    2016-04-01

    Several assessments of the mass changes of surging glaciers in the central Karakoram (and elsewhere) have shown near-zero changes over the typically decadal-long observation periods. This is in line with the theory that during a surge mass from a reservoir area is moved down-glacier to a receiving area with limited overall change. The resulting elevation changes of the glacier surface as determined by differencing DEMs from two points in time show a typical pattern (decreasing at higher, increasing at lower elevations) with a possible strong frontal advance (km scale) of the terminus. However, this is only half of the story as the observed mass gain at lower elevations is ultimately also a loss. This loss can only be determined when it is calculated separately and when sufficiently precise DEMs from the beginning and the end of a surge are available for each individual glacier. As the latter are hard to obtain, this study presents a simplified geomorphometric approach to approximate a potential maximum surge volume for 20 glaciers with a channel-like glacier fore field. By assuming a semi-elliptical cross-section of the channels, simple measurements of their average width, height and length in Google Earth provide the volume. Further glacier-specific parameters are taken from a recently compiled glacier inventory (area, slope) and Google Earth (minimum length and highest/lowest elevations) to obtain characteristics such as elevation ranges and volume. The average annual specific volume loss for each glacier is then determined by dividing the calculated surge volumes by the respective glacier area and the duration of a full surge cycle (obtained in a previous study). Which glacier area (minimum?) and surge duration (only the active phase?) have to be taken for this calculation is likely a matter of debate. With surge distances between about 1 and 5 km and channel widths (heights) between 300 and 700 (50 and 125) m, the surge volumes vary between 15 and 250 (mean 80

  18. Brazilian production development of class 2 polymeric surge arresters for transmission line application

    Energy Technology Data Exchange (ETDEWEB)

    Dellallibera, Adriano A. [Industria Eletromecanica Balestro, Mogi Mirim, SP (Brazil)], E-mail: adrianoad@balestro.com; Andrade, Antonio Donizetti de; Bezerra, Ana Cristina Guara; Duarte, Jose Vicente Pereira; Gois, Paulo Marcio Batista; Markiewicz, Rubens Leopoldo [Companhia Energetica de Minas Gerais (CEMIG), Belo Horizonte, MG (Brazil)], Emails: andonize@cemig.com.br, anacris@cemig.com.br, vicente@cemig.com.br, pgois@cemig.com.br, rlmark@cemig.com.br

    2007-07-01

    This paper shows the steeps of Brazilian class 2 ZnO lightning surge arrester development and production, aiming to attend the goal of CEMIG transmission lines performance improvement against lightning discharges action. The description of CEMIG transmission lines performance, before and after the ZnO lightning arresters installation, the necessity of use of ZnO lightning surge arrester, the prototypes manufacture, tests, problems and solutions are presented. (author)

  19. Application and Analysis for Surge Arrester on Lightning Protection of Distribution Network

    Directory of Open Access Journals (Sweden)

    Wang Daxing

    2016-01-01

    Full Text Available In order to effectively reduce lightning stroke outage rate, effect of lightning protection with surge arrester on transmission line has been generally acknowledged relative to other lightning protection measures. This article introduces in such aspects as the working principle of line surge arrester and effect of lightning protection, and also explores application for lightning arrester of distribution network to achieve difference lightning protection and improve the lightning protection performance of distribution network.

  20. An Analysis of Air Force Systems Command’s Industrial Surge Preparedness Planning.

    Science.gov (United States)

    1987-09-01

    have you taken related to suroe preparedness planning? Only three participants stated that they had taken the * basic production management courses AFIT...program phase was/(will) surge planning initially (be) put on contract? a. Suroe not applicable b. Concept Exploration c. Demonstration/Validation d...constantly. (2) Bad answers - Surge is problem in avionics only if suroes requires more test equipment to build upon to suroe rate. 7 esl equipment at least

  1. Data Assimilation within the Advanced Circulation (ADCIRC) Modeling Framework for Hurricane Storm Surge Forecasting

    KAUST Repository

    Butler, T.

    2012-07-01

    Accurate, real-time forecasting of coastal inundation due to hurricanes and tropical storms is a challenging computational problem requiring high-fidelity forward models of currents and water levels driven by hurricane-force winds. Despite best efforts in computational modeling there will always be uncertainty in storm surge forecasts. In recent years, there has been significant instrumentation located along the coastal United States for the purpose of collecting data—specifically wind, water levels, and wave heights—during these extreme events. This type of data, if available in real time, could be used in a data assimilation framework to improve hurricane storm surge forecasts. In this paper a data assimilation methodology for storm surge forecasting based on the use of ensemble Kalman filters and the advanced circulation (ADCIRC) storm surge model is described. The singular evolutive interpolated Kalman (SEIK) filter has been shown to be effective at producing accurate results for ocean models using small ensemble sizes initialized by an empirical orthogonal function analysis. The SEIK filter is applied to the ADCIRC model to improve storm surge forecasting, particularly in capturing maximum water levels (high water marks) and the timing of the surge. Two test cases of data obtained from hindcast studies of Hurricanes Ike and Katrina are presented. It is shown that a modified SEIK filter with an inflation factor improves the accuracy of coarse-resolution forecasts of storm surge resulting from hurricanes. Furthermore, the SEIK filter requires only modest computational resources to obtain more accurate forecasts of storm surge in a constrained time window where forecasters must interact with emergency responders.

  2. Application and Analysis for Surge Arrester on Lightning Protection of Distribution Network

    Directory of Open Access Journals (Sweden)

    Wang Daxing

    2015-01-01

    Full Text Available In order to effectively reduce lightning stroke outage rate, effect of lightning protection with surge arrester on transmission line has been generally acknowledged relative to other lightning protection measures. This article introduces in such aspects as the working principle of line surge arrester and effect of lightning protection, and also explores application for lightning arrester of distribution network to achieve difference lightning protection and improve the lightning protection performance of distribution network.

  3. A time series of TanDEM-X digital elevation models to monitor a glacier surge

    Science.gov (United States)

    Wendt, Anja; Mayer, Christoph; Lambrecht, Astrid; Floricioiu, Dana

    2016-04-01

    Bivachny Glacier, a tributary of the more than 70 km long Fedchenko Glacier in the Pamir Mountains, Central Asia, is a surge-type glacier with three known surges during the 20th century. In 2011, the most recent surge started which, in contrast to the previous ones, evolved down the whole glacier and reached the confluence with Fedchenko Glacier. Spatial and temporal glacier volume changes can be derived from high-resolution digital elevation models (DEMs) based on bistatic InSAR data from the TanDEM-X mission. There are nine DEMs available between 2011 and 2015 covering the entire surge period in time steps from few months up to one year. During the surge, the glacier surface elevation increased by up to 130 m in the lower part of the glacier; and change rates of up to 0.6 m per day were observed. The surface height dataset was complemented with glacier surface velocity information from TerraSAR-X/ TanDEM-X data as well as optical Landsat imagery. While the glacier was practically stagnant in 2000 after the end of the previous surge in the 1990s, the velocity increase started in 2011 in the upper reaches of the ablation area and successively moved downwards and intensified, reaching up to 4.0 m per day. The combination of surface elevation changes and glacier velocities, both of high temporal and spatial resolution, provides the unique opportunity to describe and analyse the evolution of the surge in unprecedented detail. Especially the relation between the mobilization front and the local mass transport provides insight into the surge dynamics.

  4. Performance of metal oxide gapless surge arresters for HVDC systems

    Energy Technology Data Exchange (ETDEWEB)

    Diseko, N.L.

    1990-09-01

    An examination of the electrical stresses which may be imposed upon metal oxide surge arresters in a dc converter station is undertaken by means of simulation of the dc system and associated ac systems in the time domain using a digital computer program. Detailed models of a dc link are developed for temporary overvoltage stresses and steep front stresses. The most critical stresses for each type of dc station arrester due to converter faults and converter malfunctions are identified. The energy stresses were generally determined to be dependent on the converter control and protection strategies adopted during the faults. The arrester energy stresses for faults on both the line side and valve side busses of the converter transformer were determined to be sensitive to the instant of fault application and the duration of the fault. The arrester stresses for ac bus faults were analyzed in detail to determine their statistical distribution relative to the point on wave at which the fault occurred in each affected phase, and to the instant of fault clearance in each phase. Generally, the highest stresses occur for sequential fault occurrence in the phases compared with simultaneous faults. The studies indicate that the stresses in the arresters in a dc pile experiencing the worst duty depend on the number of arresters represented. Modelling only one arrester of a series-connected group does not provide correct results when the fault condition imposes duty on more than one of the arresters in the group. The study also indicates that the highest stresses do not necessarily occur in the single arrester connected across the valve with the highest prospective overvoltage. Hence the capability to represent all valve arresters within one pole is necessary when determining the most onerous stresses. 11 refs., 79 figs., 28 tabs.

  5. Reference Model 5 (RM5): Oscillating Surge Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Y. H. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Jenne, D. S. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Thresher, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Copping, A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Geerlofs, S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hanna, L. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-01-01

    This report is an addendum to SAND2013-9040: Methodology for Design and Economic Analysis of Marine Energy Conversion (MEC) Technologies. This report describes an Oscillating Water Column Wave Energy Converter (OSWEC) reference model design in a complementary manner to Reference Models 1-4 contained in the above report. A conceptual design for a taut moored oscillating surge wave energy converter was developed. The design had an annual electrical power of 108 kilowatts (kW), rated power of 360 kW, and intended deployment at water depths between 50 m and 100 m. The study includes structural analysis, power output estimation, a hydraulic power conversion chain system, and mooring designs. The results were used to estimate device capital cost and annual operation and maintenance costs. The device performance and costs were used for the economic analysis, following the methodology presented in SAND2013-9040 that included costs for designing, manufacturing, deploying, and operating commercial-scale MEC arrays up to 100 devices. The levelized cost of energy estimated for the Reference Model 5 OSWEC, presented in this report, was for a single device and arrays of 10, 50, and 100 units, and it enabled the economic analysis to account for cost reductions associated with economies of scale. The baseline commercial levelized cost of energy estimate for the Reference Model 5 device in an array comprised of 10 units is $1.44/kilowatt-hour (kWh), and the value drops to approximately $0.69/kWh for an array of 100 units.

  6. The insulation coordination and surge arrester design for HTS cable system in Icheon substation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hansang, E-mail: Hansang80@korea.ac.kr [School of Railway and Electrical Engineering, Kyungil University, Hayang-eup, Gyeongsan-si, Gyeongsangbuk-do 712-701 (Korea, Republic of); Yoon, Dong-Hee [Department of New and Renewable Energy, Kyungil University, Hayang-eup, Gyeongsan-si, Gyeongsangbuk-do 712-701 (Korea, Republic of); Lee, Seung-Ryul [Korea Electrotechnology Research Institute, Naeson-dong, Uiwang-si, Gyeonggi-do 437-080 (Korea, Republic of); Yang, Byeong-Mo [Korea Electric Power Research Institute, Munji-dong, Yuseong-gu, Daejeon 305-760 (Korea, Republic of); Jang, Gilsoo, E-mail: gjang@korea.ac.kr [School of Electrical Engineering, Korea University, Anam-dong 5-ga, Seongbuk-gu, Seoul 136-713 (Korea, Republic of)

    2013-01-15

    Highlights: ► It is necessary to study lightning response of the HTS cable. ► The analytic model has been developed for the HTS cable in the Icheon substation. ► Well-designed surge arrester has been verified through PSCAD/EMTDC simulations. -- Abstract: This paper proposes an insulation coordination and surge arrester design for HTS (High-Temperature Superconducting) cable system in Icheon substation in Korea. In the aspect of the economic analysis, since the HTS cable is very expensive, the insulation coordination to prevent the dielectric breakdown caused by the lightning surge should be considered carefully. Also, in the aspect of the power system reliability, since the HTS cable has much more capacity compared than conventional power cables and the ripple effect from the HTS cable failure may lead to the wide area blackout, an intensive study for insulation coordination from lightning surge is one of the most important considerations. In this paper, the insulation coordination for lightning surge is verified using HTS cable and power equipment models and the design of the proper surge arrester is proposed.

  7. Storm surge evolution and its relationship to climate oscillations at Duck, NC

    Science.gov (United States)

    Munroe, Robert; Curtis, Scott

    2017-07-01

    Coastal communities experience increased vulnerability during storm surge events through the risk of damage to coastal infrastructure, erosion/deposition, and the endangerment of human life. Policy and planning measures attempt to avoid or mitigate storm surge consequences through building codes and setbacks, beach stabilization, insurance rates, and coastal zoning. The coastal emergency management community and public react and respond on shorter time scales, through temporary protection, emergency stockpiling, and evacuation. This study utilizes time series analysis, the Kolmogorov-Smirnov (K-S) test, Pearson's correlation, and the generalized extreme value (GEV) theorem to make the connection between climate oscillation indices and storm surge characteristics intra-seasonally to inter-annually. Results indicate that an El Niño (+ENSO), negative phase of the NAO, and positive phase of the PNA pattern all support longer duration and hence more powerful surge events, especially in winter. Increased surge duration increases the likelihood of extensive erosion, inland inundation, among other undesirable effects of the surge hazard.

  8. The value of wetlands in protecting southeast louisiana from hurricane storm surges.

    Directory of Open Access Journals (Sweden)

    Edward B Barbier

    Full Text Available The Indian Ocean tsunami in 2004 and Hurricanes Katrina and Rita in 2005 have spurred global interest in the role of coastal wetlands and vegetation in reducing storm surge and flood damages. Evidence that coastal wetlands reduce storm surge and attenuate waves is often cited in support of restoring Gulf Coast wetlands to protect coastal communities and property from hurricane damage. Yet interdisciplinary studies combining hydrodynamic and economic analysis to explore this relationship for temperate marshes in the Gulf are lacking. By combining hydrodynamic analysis of simulated hurricane storm surges and economic valuation of expected property damages, we show that the presence of coastal marshes and their vegetation has a demonstrable effect on reducing storm surge levels, thus generating significant values in terms of protecting property in southeast Louisiana. Simulations for four storms along a sea to land transect show that surge levels decline with wetland continuity and vegetation roughness. Regressions confirm that wetland continuity and vegetation along the transect are effective in reducing storm surge levels. A 0.1 increase in wetland continuity per meter reduces property damages for the average affected area analyzed in southeast Louisiana, which includes New Orleans, by $99-$133, and a 0.001 increase in vegetation roughness decreases damages by $24-$43. These reduced damages are equivalent to saving 3 to 5 and 1 to 2 properties per storm for the average area, respectively.

  9. 3D Simulation of Storm Surge Disaster Based on Scenario Analysis

    Institute of Scientific and Technical Information of China (English)

    王晓玲; 孙小沛; 张胜利; 孙蕊蕊; 李瑞金; 朱泽彪

    2016-01-01

    The occurrence of storm surge disaster is often accompanied with floodplain, overflow, dike breach and other complex phenomena, while current studies on storm surge flooding are more concentrated on the 1D/2D numerical simulation of single disaster scenario (floodplain, overflow or dike breach), ignoring the composite ef-fects of various phenomena. Therefore, considering the uncertainty in the disaster process of storm surge, scenario analysis was firstly proposed to identify the composite disaster scenario including multiple phenomena by analyzing key driving forces, building scenario matrix and deducing situation logic. Secondly, by combining the advantages of k-ωand k-εmodels in the wall treatment, a shear stress transmission k-ωmodel coupled with VOF was proposed to simulate the 3D flood routing for storm surge disaster. Thirdly, risk degree was introduced to make the risk analysis of storm surge disaster. Finally, based on the scenario analysis, four scenarios with different storm surge intensity (100-year and 200-year frequency) were identified in Tianjin Binhai New Area. Then, 3D numerical simulation and risk map were made for the case.

  10. Cortisol interferes with the estradiol-induced surge of luteinizing hormone in the ewe.

    Science.gov (United States)

    Wagenmaker, Elizabeth R; Breen, Kellie M; Oakley, Amy E; Pierce, Bree N; Tilbrook, Alan J; Turner, Anne I; Karsch, Fred J

    2009-03-01

    Two experiments were conducted to test the hypothesis that cortisol interferes with the positive feedback action of estradiol that induces the luteinizing hormone (LH) surge. Ovariectomized sheep were treated sequentially with progesterone and estradiol to create artificial estrous cycles. Cortisol or vehicle (saline) was infused from 2 h before the estradiol stimulus through the time of the anticipated LH surge in the artificial follicular phase of two successive cycles. The plasma cortisol increment produced by infusion was approximately 1.5 times greater than maximal concentrations seen during infusion of endotoxin, which is a model of immune/inflammatory stress. In experiment 1, half of the ewes received vehicle in the first cycle and cortisol in the second; the others were treated in reverse order. All ewes responded with an LH surge. Cortisol delayed the LH surge and reduced its amplitude, but both effects were observed only in the second cycle. Experiment 2 was modified to provide better control for a cycle effect. Four treatment sequences were tested (cycle 1-cycle 2): vehicle-vehicle, cortisol-cortisol, vehicle-cortisol, cortisol-vehicle. Again, cortisol delayed but did not block the LH surge, and this delay occurred in both cycles. Thus, an elevation in plasma cortisol can interfere with the positive feedback action of estradiol by delaying and attenuating the LH surge.

  11. Effect of Hydraulic Accumulator on Pressure Surge of a Hydrostatic Transmission System

    Science.gov (United States)

    Kumar, Ajit; Das, Jayanta; Dasgupta, Kabir; Barnwal, Manish Kumar

    2017-05-01

    Hydraulic power system is generally used in off-road vehicles for power transmission such as Heavy Earth Moving Machineries (HEMM). Their energy efficiency and unsubstantial failure becomes an extensive subject of analysis. Various arrangements in the system are compassed along with the utilization of some appropriate components. Application of a hydraulic accumulator is one among them. Benefits of accumulator is its multi-purpose usages like energy saving and pressure surge damping. This paper deals with the control of pressure surges in the hydraulic system and energy saving from the surges by using accumulator. For this purpose, the simulation of the hydraulic system is done in MATLAB/SimulinkR environment and an external disturbance is introduced to generate the pressure surge. The surge absorptivity of the accumulator is studied for different sizes at different pre-charged conditions of the accumulator. The discharge characteristics of different sized accumulators are also analyzed in this paper. It is observed that the ability to absorb the surge and stabilize the system is high in the smaller capacity accumulator. However the energy delivery time of larger sized accumulator is high.

  12. An ensemble study of extreme North Sea storm surges in a changing climate

    Directory of Open Access Journals (Sweden)

    A. Sterl

    2009-05-01

    Full Text Available The height of storm surges is extremely important for a low-lying country like the Netherlands. By law, part of the coastal defence system has to withstand a water level that on average occurs only once every 10 000 years. The question then arises whether and how climate change affects the heights of extreme storm surges. Published research points to only small changes. However, due to the limited amount of data available results are usually limited to relatively frequent extremes like the annual 99%-ile. We here report on results from a 17-member ensemble of North Sea water levels spaning the period 1950–2100. It was created by forcing a surge model of the North Sea with meteorological output from a state-of-the-art global climate model which has been driven by greenhouse gas emissions following the SRES A1b scenario. The large ensemble size enables us to calculate 10 000 year return water levels with a low statistical uncertainty. We find no statistically significant change in the 10 000 year return values of surge heights along the Dutch during the 21st century. Also a higher sea level resulting from global warming does not impact the height of the storm surges. As a side effect of our simulations we also obtain results on the interplay between surge and tide.

  13. Annual bed statistics give a misleading picture of hospital surge capacity.

    Science.gov (United States)

    DeLia, Derek

    2006-10-01

    I describe how annual hospital surge capacity is affected by within-year variation in patient volume and bed supply. Surge capacity was measured as the percentage and total number of hospital beds that are not occupied by patients. Administrative data were used to calculate these bed statistics for 78 hospitals in New Jersey--statewide and by emergency planning regions--in 2003. Annual bed statistics were compared to more refined calculations for each day of the year. Calculated numbers of empty beds were compared to federal disaster planning benchmarks. Annual bed statistics showed no major limitations on surge capacity. Statewide occupancy rates were well below 80% (ie, more than 20% of beds were empty), and the number of empty beds that were set up and staffed (ie, maintained) was well above federal disaster planning benchmarks. In contrast, daily bed statistics reveal long periods in 2003 when regional and statewide surge capacity was severely strained. Strained capacity was most likely to occur on Tuesdays through Fridays and least likely to occur on weekends. On 212 days, statewide occupancy of maintained beds met or exceeded 85%. This occupancy rate met or exceeded 90% and 95% on 88 and 4 days, respectively. On 288 days, the statewide number of empty maintained beds fell below the federal planning benchmark. Annual bed statistics give a misleading picture of hospital surge capacity. Analysis of surge capacity should account for daily variation in patient volume and within-year variation in bed supply.

  14. 玉米全膜双垄沟播与半膜平作对比分析%The Comparative Analysis of Maize with Mulched Double Furrow Planting and Conventional Planting with Half-mulching

    Institute of Scientific and Technical Information of China (English)

    王翠花; 田立双

    2016-01-01

    对比分析了全膜双垄沟播玉米和半膜平作玉米的生育期、苗期生长情况、苗期土壤含水量、产量及构成因素,结果表明,全膜双垄沟播的增产效果、保墒效果均优于半膜平作,更适合在旱作区推广。%By comparing the growing period、Seedling growth、soil water content in seedling period、yield and itscom-ponent of maize with mulched double furrow planting and conventional planting with half-mulching, we know that the yield increasing、soil water conservation of mulched double furrow planting are better than that of flat-planting with half-mulching, and mulched double furrow planting is more suitable for planting in the dry region.

  15. Identification of storm surge vulnerable areas in the Philippines through the simulation of Typhoon Haiyan-induced storm surge levels over historical storm tracks

    Directory of Open Access Journals (Sweden)

    J. P. Lapidez

    2015-07-01

    Full Text Available Super Typhoon Haiyan entered the Philippine Area of Responsibility (PAR on 7 November 2013, causing tremendous damage to infrastructure and loss of lives mainly due to the storm surge and strong winds. Storm surges up to a height of 7 m were reported in the hardest hit areas. The threat imposed by this kind of natural calamity compelled researchers of the Nationwide Operational Assessment of Hazards (Project NOAH which is the flagship disaster mitigation program of the Department of Science and Technology (DOST of the Philippine government to undertake a study to determine the vulnerability of all Philippine coastal communities to storm surges of the same magnitude as those generated by Haiyan. This study calculates the maximum probable storm surge height for every coastal locality by running simulations of Haiyan-type conditions but with tracks of tropical cyclones that entered PAR from 1948–2013. One product of this study is a list of the 30 most vulnerable coastal areas that can be used as a basis for choosing priority sites for further studies to implement appropriate site-specific solutions for flood risk management. Another product is the storm tide inundation maps that the local government units can use to develop a risk-sensitive land use plan for identifying appropriate areas to build residential buildings, evacuation sites, and other critical facilities and lifelines. The maps can also be used to develop a disaster response plan and evacuation scheme.

  16. Identification of storm surge vulnerable areas in the Philippines through the simulation of Typhoon Haiyan-induced storm surge levels over historical storm tracks

    Directory of Open Access Journals (Sweden)

    J. P. Lapidez

    2015-02-01

    Full Text Available Super Typhoon Haiyan entered the Philippine Area of Responsibility (PAR 7 November 2013, causing tremendous damage to infrastructure and loss of lives mainly due to the storm surge and strong winds. Storm surges up to a height of 7 m were reported in the hardest hit areas. The threat imposed by this kind of natural calamity compelled researchers of the Nationwide Operational Assessment of Hazards (Project NOAH, the flagship disaster mitigation program of the Department of Science and Technology (DOST, Government of the Philippines, to undertake a study to determine the vulnerability of all Philippine coastal communities to storm surges of the same magnitude as those generated by Haiyan. This study calculates the maximum probable storm surge height for every coastal locality by running simulations of Haiyan-type conditions but with tracks of tropical cyclones that entered PAR from 1948–2013. One product of this study is a list of the 30 most vulnerable coastal areas that can be used as basis for choosing priority sites for further studies to implement appropriate site-specific solutions for flood risk management. Another product is the storm tide inundation maps that the local government units can use to develop a risk-sensitive land use plan for identifying appropriate areas to build residential buildings, evacuation sites, and other critical facilities and lifelines. The maps can also be used to develop a disaster response plan and evacuation scheme.

  17. Simulated storm surge effects on freshwater coastal wetland soil porewater salinity and extractable ammonium levels: Implications for marsh recovery after storm surge

    Science.gov (United States)

    McKee, M.; White, J. R.; Putnam-Duhon, L. A.

    2016-11-01

    Coastal wetland systems experience both short-term changes in salinity, such as those caused by wind-driven tides and storm surge, and long-term shifts caused by sea level rise. Salinity increases associated with storm surge are known to have significant effects on soil porewater chemistry, but there is little research on the effect of flooding length on salt penetration depth into coastal marsh soils. A simulated storm surge was imposed on intact soil columns collected from a non-vegetated mudflat and a vegetated marsh site in the Wax Lake Delta, LA. Triplicate intact cores were continuously exposed to a 35 salinity water column (practical salinity scale) for 1, 2, and 4 weeks and destructively sampled in order to measure porewater salinity and extractable NH4sbnd N at two cm depth intervals. Salinity was significantly higher in the top 8 cm for both the marsh and mudflat cores after one week of flooding. After four weeks of flooding, salinity was significantly higher in marsh and mudflat cores compared to the control (no salinity) cores throughout the profile for both sites. Extractable ammonium levels increased significantly in the marsh cores throughout the experiment, but there was only a marginally (p coastal marsh soil in just one week. This vertical intrusion of salt can potentially negatively impact macrophytes and associated microbial communities for significantly longer term post-storm surge.

  18. (abstract) A Mini-Surge on the Ryder Glacier, Greenland

    Science.gov (United States)

    Joughin, I.; Tulaczyk, Slawek; Fahnestock, M.; Kwok, R.

    1996-01-01

    We have detected a dramatic short-term speedup of the Ryder Glacier, Greenland, using satellite radar interferometry. The accelerated flow represents a substantial, though short-lived, change in the ice discharge from the basin. We use the term.

  19. Two New Freshwater Woloszynskioids Asulcocephalium miricentonis gen. et sp. nov. and Leiocephalium pseudosanguineum gen. et sp. nov. (Suessiaceae, Dinophyceae) Lacking an Apical Furrow Apparatus.

    Science.gov (United States)

    Takahashi, Kazuya; Moestrup, Øjvind; Jordan, Richard W; Iwataki, Mitsunori

    2015-12-01

    Two new woloszynskioid dinoflagellates, Asulcocephalium miricentonis gen. et sp. nov. and Leiocephalium pseudosanguineum gen. et sp. nov., are described from Japanese freshwater ponds on the basis of bright field and fluorescence light microscopy, scanning and transmission electron microscopy, and molecular phylogeny inferred from rDNA sequences. Asulcocephalium miricentonis has a spherical anterior nucleus and chloroplast with a pyrenoid penetrated by the cytoplasm. This species has 9-12 latitudinal series of amphiesmal vesicles (AVs), including an apparently large AV on the right ventral side of the epicone. Leiocephalium pseudosanguineum has a U-shaped nucleus in the epicone and chloroplasts without a pyrenoid. This species has at least 24 latitudinal series of AVs. The characteristic features of both species were brick-like material (type E) in the eyespot and the lack of an apical furrow. These features coincide with those of Polarella glacialis, but the two species differ in cell shape, number and arrangement of AVs, shape of resting cysts, and habitats; i.e., P. glacialis has been reported only from marine cold waters. Molecular phylogeny revealed that A. miricentonis and L. pseudosanguineum were positioned in the Suessiaceae and closely related to Piscinoodinium sp., but their relationship to Polarella and other reported taxa was not supported.

  20. Alternate furrow irrigation of four fresh-market tomato cultivars under semi-arid condition of Ethiopia – Part II: Physiological response

    Directory of Open Access Journals (Sweden)

    Ashinie Bogale

    2016-11-01

    Full Text Available Understanding the variation in physiological response to deficit irrigation together with better knowledge on physiological characteristics of different genotypes that contribute to drought adaptation mechanisms would be helpful in transferring different irrigation technologies to farmers. A field experiment was carried to investigate the physiological response of four tomato cultivars (Fetan, Chali, Cochoro and ARP Tomato d2 to moderate water deficit induced by alternate furrow irrigation (AFI and deficit irrigation (DI under semi-arid condition of Ethiopia during 2013 and 2014. The study also aimed at identifying physiological attributes to the fruit yield of tomato under different deficit irrigation techniques. A factorial combination of irrigation treatments and cultivar were arranged in a complete randomized design with three replicates. Results showed that stomatal conductance (g_s was significantly reduced while photosynthetic performance measured as chlorophyll fluorescence (Fv’/Fm’, relative water content (RWC and leaf ash content remained unaffected under deficit irrigations. Significant differences among cultivars were found for water use efficiency (WUE, g_s, chlorophyll content (Chl_SPAD, normal difference vegetation index (NDVI, leaf ash content and fruit growth rate. However, cultivar differences in WUE were more accounted for by the regulation of g_s, therefore, g_s could be useful for breeders for screening large numbers of genotypes with higher WUE under deficit irrigation condition. The study result also demonstrated that cultivar with traits that contribute to achieve higher yields under deficit irrigation strategies has the potential to increase WUE.

  1. Twelve-year cyclic surging episode at Donjek Glacier in Yukon, Canada

    Science.gov (United States)

    Furuya, M.; Abe, T.; Sakakibara, D.

    2015-12-01

    Surge-type glaciers exhibit several-fold to orders-of-magnitude speed-up during the short active phase, resulting in km-scale terminus advance. Although there are many surge-type glaciers near the border of Alaska and the Yukon, the generation mechanisms remain uncertain because of limited and few continuous observations. To better understand the surge dynamics and predict the next event, it is essential to examine the entire surge cycles. Here we use Landsat optical imageries to reveal the long-term evolutions, and report three surging episodes at Donjek Glacier in Yukon, Canada. Using the Landsat images, we found three surging events in 1989, 2001, and 2013. In the 2001 event, the surface speed significantly increased by up to 4.5 m/d; during the quiescent phases it was ~0.5 m/d at the terminus. While the duration of active phase is about 4~5 and 2~3 year in the 2001 and 2013 events, the period in the 1989 event is unclear because of the lack of high temporal resolution data. Remarkably, the surging area is limited to the ~20-km section from the terminus instead of the entire glacier. Moreover, we examined the terminus area changes from 1975 to 2014. Although the area has been secularly decreasing probably due to the tread of global warming, it has also revealed four significant fluctuations during the nearly forty years. Comparing the speed and the area changes, the three speed-up events correspond to the terminus area fluctuations with a few time lags. It turns out that the surge event has been quite regularly repeating every twelve years. Although the behavior is rather similar to that in Svalbard glaciers in terms of maximum speed and unclear initiation season, the recurrence interval is much shorter than other nearby surges. Considering that the surge events seem to have initiated around significantly narrower area than upstream, the strong valley constriction may control the regularity as well as the twelve-year recurrence time.

  2. The eSurge-Venice project: altimeter and scatterometer satellite data to improve the storm surge forecasting in the city of Venice

    Science.gov (United States)

    Zecchetto, Stefano; De Biasio, Francesco; Umgiesser, Georg; Bajo, Marco; Vignudelli, Stefano; Papa, Alvise; Donlon, Craig; Bellafiore, Debora

    2013-04-01

    On the framework of the Data User Element (DUE) program, the European Space Agency is funding a project to use altimeter Total Water Level Envelope (TWLE) and scatterometer wind data to improve the storm surge forecasting in the Adriatic Sea and in the city of Venice. The project will: a) Select a number of Storm Surge Events occurred in the Venice lagoon in the period 1999-present day b) Provide the available satellite Earth Observation (EO) data related to the Storm Surge Events, mainly satellite winds and altimeter data, as well as all the available in-situ data and model forecasts c) Provide a demonstration Near Real Time service of EO data products and services in support of operational and experimental forecasting and warning services d) Run a number of re-analysis cases, both for historical and contemporary storm surge events, to demonstrate the usefulness of EO data The re-analysis experiments, based on hindcasts performed by the finite element 2-D oceanographic model SHYFEM (https://sites.google.com/site/shyfem/), will 1. use different forcing wind fields (calibrated and not calibrated with satellite wind data) 2. use Storm Surge Model initial conditions determined from altimeter TWLE data. The experience gained working with scatterometer and Numerical Weather Prediction (NWP) winds in the Adriatic Sea tells us that the bias NWP-Scatt wind is negative and spatially and temporally not uniform. In particular, a well established point is that the bias is higher close to coasts then offshore. Therefore, NWP wind speed calibration will be carried out on each single grid point in the Adriatic Sea domain over the period of a Storm Surge Event, taking into account of existing published methods. Point #2 considers two different methodologies to be used in re-analysis tests. One is based on the use of the TWLE values from altimeter data in the Storm Surge Model (SSM), applying data assimilation methodologies and trying to optimize the initial conditions of the

  3. Mapping Risks Due To Storm Surges Within The Coastal Zone

    Science.gov (United States)

    Mai, S.; Zimmermann, C.

    The coast protection at the Wadden Sea coastline of Lower Saxony, Germany, is mainly guaranteed by sea dikes. In case of a failure of these dikes a total area of approx. 7.130 km2 is endangered from inundation. Besides that approx. 1.3 million people and economic values of 150 billion Euro are at risk. The consequences of dike failure show a large spatial variability. However today's design of sea dikes does not take into account the spatial variability, i.e. coastal areas with high losses in case of dike failure are not protected better than those with low. In order to improve this sit- uation a scheme for risk analysis was developed and applied at the estuaries Jade and Weser including the cities Wilhelmshaven, Bremerhaven, Bremen and Cuxhaven. The scheme of risk analysis comprises on the one hand a calculation of the probability of dike failure and a determination of the area flooded in case of dike breaching and on the other hand a register of all values, i.e. houses, industrial estates and infrastructure, within the hinterland. The different steps are integrated and linked to a Geographical Information System GIS using ARCVIEW. Within the developed design scheme failure of sea dikes is related to wave overtop- ping. Therefore the probability of failure is determined from the joined probability of tidal high water-levels and waves. The statistics of latter are calculated from the wind statistics using the numerical wave model SWAN. The time dependent flooding process after dike breaches is calculated with the numer- ical model MIKE 21 HD providing information on the depth, velocity and duration of the inundation. The sensitivity of the calculations of the inundation characteristics with respect to the width of the dike breach, the surface roughness and the character- istics of the storm surge is evaluated. The inundation depth and speed is used to estimate the damage factor, i.e. the ratio of the expected loss after inundation and the maximum possible loss. The

  4. Morning blood pressure surge: the reliability of different definitions.

    Science.gov (United States)

    Stergiou, George S; Mastorantonakis, Stylianos E; Roussias, Leonidas G

    2008-08-01

    Preliminary evidence suggests that the morning surge (MS) in blood pressure (BP) is an independent predictor of cerebrovascular disease. However, the optimal definition of MS is uncertain. To compare the reproducibility of several MS definitions used in the literature, 132 untreated hypertensives were assessed with ambulatory BP monitoring twice, 2 weeks apart. Five MS definitions were compared. MS-1: the average BP of the first hour after rising minus the average BP of the first hour before rising; MS-2: BP 2 h after rising minus that of 2 h before rising; MS-3: BP 3 h after rising minus that of 3 h before rising; MS-4: BP 2 h after rising minus the average BP during sleep; MS-5: BP 2 h after rising minus the average BP of 3 consecutive readings, centered on the lowest reading during sleep. The reproducibility of each MS definition was assessed using the concordance correlation coefficient (CCC), the standard deviation of differences (SDD) and the coefficient of variation (CV) between repeated MS assessments, and the agreement in detecting "surgers," defined as subjects at the top quartile (Q4) of the MS distribution. CCCs were 0.20/0.30, 0.43/0.45, 0.53/0.51, 0.51/0.47, and 0.46/0.48 (systolic/diastolic) for MS-1 to MS-5 respectively; SDDs were 14.3/11.4, 12.1/9.9, 11.2/9.5, 10.3/8.2, and 11.9/9.8, respectively; CVs were 0.49/0.57, 0.44/0.39, 0.37/0.35, 0.36/0.31, and 0.27/0.24, respectively; and the agreement in detecting "surgers" was 69%/70%, 71%/76%, 75%/75%, 81%/83%, and 74%/75%, with kappa of 0.18/0.20, 0.23/0.36, 0.33/0.33, 0.49/0.53 and 0.29/0.31, respectively. There are important differences in the reproducibility of MS calculated by different methods. MS4 appears to provide the most reproducible definition of MS.

  5. Selection of gonadotrophin surge attenuating factor phage antibodies by bioassay

    Directory of Open Access Journals (Sweden)

    Mason Helen D

    2005-09-01

    Full Text Available Abstract Background We aimed to combine the generation of "artificial" antibodies with a rat pituitary bioassay as a new strategy to overcome 20 years of difficulties in the purification of gonadotrophin surge-attenuating factor (GnSAF. Methods A synthetic single-chain antibody (Tomlinson J phage display library was bio-panned with partially purified GnSAF produced by cultured human granulosa/luteal cells. The initial screening with a simple binding immunoassay resulted in 8 clones that were further screened using our in-vitro rat monolayer bioassay for GnSAF. Initially the antibodies were screened as pooled phage forms and subsequently as individual, soluble, single-chain antibody (scAbs forms. Then, in order to improve the stability of the scAbs for immunopurification purposes, and to widen the range of labelled secondary antibodies available, these were engineered into full-length human immunoglobulins. The immunoglobulin with the highest affinity for GnSAF and a previously described rat anti-GnSAF polyclonal antiserum was then used to immunopurify bioactive GnSAF protein. The two purified preparations were electrophoresed on 1-D gels and on 7 cm 2-D gels (pH 4–7. The candidate GnSAF protein bands and spots were then excised for peptide mass mapping. Results Three of the scAbs recognised GnSAF bioactivity and subsequently one clone of the purified scAb-derived immunoglobulin demonstrated high affinity for GnSAF bioactivity, also binding the molecule in such as way as to block its bioactivity. When used for repeated immunopurification cycles and then Western blot, this antibody enabled the isolation of a GnSAF-bioactive protein band at around 66 kDa. Similar results were achieved using the rat anti-GnSAF polyclonal antiserum. The main candidate molecules identified from the immunopurified material by excision of 2-D gel protein spots was human serum albumin precursor and variants. Conclusion This study demonstrates that the combination of

  6. Studies on scaled models for gas entrainment in the surge tank of LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Ramdasu, D.; Shivakumar, N.S.; Padmakumar, G.; Anand Babu, C.; Vaidyanathan, G. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Rammohan, S.; Sreekala, S.K.; Manikandan, S.; Saseendran, S. [Fluid Control Research Institute, Palghat (India)

    2007-07-01

    This paper presents the studies carried out in the different scale models of Surge tank used in the secondary circuit of Liquid metal fast breeder reactor (LMFBR). Surge tank acquires importance because of its ability to take care of pressure surges in case of a sodium water reaction in Steam Generators (SG). The blanket of argon cover gas above the sodium free surface in the surge tank acts as a cushion for the surges. At the same time, argon gas is a source of entrainment into the sodium which is undesirable from the consideration of effective heat transfer in Inter mediate Heat Exchanger and SG, cavitation in pumps and operational problems of continuous feed and bleed of cover gas, thus leading to unfavourable reactor operating conditions. To investigate the phenomenon of gas entrainment in surge tank, hydraulic experiments were conducted in water using 1/38, 1/32, 1/22 and 1/12 scale models with Froude similarity. The minimum height of liquid column required to avoid gas entrainment was determined using different types of internal devices. Experiments were carried out in the 5/8 scale model to confirm the results of the smaller scale models. It was found that free surface height to avoid gas entrainment varies for different scale models. The combination of Pepper pot with ring plate was found to be the most effective in avoiding gas entrainment at H/D equals 1.28 where H is the height of liquid column in the tank from tank bottom and D is the inner diameter of surge tank.

  7. Tsivat Basin conduit system persists through two surges, Bering Piedmont Glacier, Alaska

    Science.gov (United States)

    Fleisher, P.J.; Cadwell, D.H.; Muller, E.H.

    1998-01-01

    The 1993-1995 surge of Bering Glacier, Alaska, occurred in two distinct phases. Phase 1 of the surge began on the eastern sector in July, 1993 and ended in July, 1994 after a powerful outburst of subglacial meltwater into Tsivat Lake basin on the north side of Weeping Peat Island. Within days, jokulhlaup discharge built a 1.5 km2 delta of ice blocks (25-30 m) buried in outwash. By late October 1994, discharge temporarily shifted to a vent on Weeping Peat Island, where a second smaller outburst dissected the island and built two new sandar. During phase 2, which began in spring 1995 and ended within five months, continuous discharge issued from several vents along the ice front on Weeping Peat Island before returining to the Tsivat Basin. Surge related changes include a five- to six-fold increase in meltwater turbidity; the redirection of supercooled water in two ice-contact lakes; and an increase in the rate of glaciolacustrine sedimentation. US Geological Survey aerial photos by Austin Post show large ice blocks in braided channels indicating excessive subglacial discharge in a similar position adjacent to Weeping Peat Island during the 1966-1967 surge. During the subsequent three decades of retreat, the location of ice-marginal, subglacial discharge vents remained aligned on a linear trend that describes the position of a persistent subglacial conduit system. The presence of a major conduit system, possibly stabilized by subglacial bedrock topography, is suggested by: 1) high-level subglacial meltwater venting along the northern side of Weeping Peat Island during the 1966-1967 surge, 2) persistent low-level discharge between surges, and 3) the recurrence of localizing meltwater outbursts associated with both phases of the 1993-1005 surge.

  8. 秸秆深埋还田开沟扶垄犁设计及试验研究%Design and Testing of Plough for Deep Furrowing and Ridging of Straw Amendment Fields

    Institute of Scientific and Technical Information of China (English)

    王瑞丽; 黄毅; 魏凤兰; 白雪卫; 刘鄂; 张玉龙

    2011-01-01

    针对我国北方旱作地区春玉米播种时墒情不够、肥力不足的问题,提出了在秋季收获后进行深开沟、沟内铺放秸秆、覆土起垄整垄、垄上覆膜的秸秆深埋,蓄积秋冬降水的土肥水跨季节联合调控技术.研制了秸秆深埋还田开沟扶垄犁.采用对称式可翻转犁架,实现开沟、覆土、起垄、整垄联合作业.田间性能试验结果表明:该机开沟深度可以达到40cm,沟形规整,覆土效果较好,整垄效率高,垄形符合农艺要求.采用该机进行秋季秸秆深埋还田,可以有效提高土壤水分含量,提高玉米产量.%Zn northern China, soil moisture content and fertility are low at the time of maize planting. A solution was proposed for this problem. After harvesting in the autumn, the soil was tilled to create deep furrows filled with straw and backfilled to form ridges mulched with a plastic film. A plough was designed to furrow the soil properly, bury the straw deeply, form ridges with a suitable shape, and to puncture the membranes for spring seeding. The rotary plough with a symmetrical frame was developed, built and tested. The results of field tests showed that the plough could create furrows up to a depth of 40 cm. The shaping and backfilling of the furrows were done effectively and efficiently according with agricultural standards. The use of the plough and the technique of filling the furrows with straw and mulching with a plastic film were used in a field test This technique resulted in increased soil moisture content and productivity of corn.

  9. Laboratory Research of the Two-Layer Liquid Dynamics at the Wind Surge in a Strait Canal

    Directory of Open Access Journals (Sweden)

    S.F. Dotsenko

    2017-06-01

    Full Text Available The results of laboratory experiments in a straight aerohydrocanal of the rectangular cross-section filled with the two-layer (fresh-salty liquid are represented. The disturbance generator is the air flow directed to the area above the canal. The cases of the two-layer liquid dynamics in the canal with the horizontal flat bottom and in the presence of the bottom obstacle of finite width are considered. It is shown that during the surge in the straight canal, one of the possible exchange mechanisms on the boundary of fresh and salty layers may consist in the salt water emissions (resulted from the Kelvin-Helmholtz instability to the upper freshwater layer. The subsequent eviction can possibly be accompanied by occurrence of undulations at the interface. Besides, the evictions can be followed by formation of the oscillating layer, i.e. the layer with maximum density gradient the oscillations of which propagate to the overlying layers. Presence of the bottom obstacle complicates the structure of the two-layer liquid motions. In particular, it results in emergence of the mixed layers and transformation of the flow behind the obstacle into a turbulent one, formation of the wave-like disturbances over the obstacle, sharp change of the interface position and occurrence of large-scale vortices with the horizontal axes. It is revealed that the maximum peak of the flow velocity horizontal component is shifted upstream from the obstacle.

  10. 尾矿膏体蠕动堆存技术在窄沟陡坡降雨集中尾矿库的应用%Application of tailings paste snailing stockpiling technique in tailings dam below steep slopes with narrow furrows in precipitation-intense seasons

    Institute of Scientific and Technical Information of China (English)

    梁凯河; 周东平; 滕永清; 姜良友; 王杰; 胡海涛

    2016-01-01

    为解决高寒陡坡尾矿库下游式排放方式降雨集中季节在窄沟陡坡形成的泥石流冲击尾矿坝等问题,对高海拔尾矿库采用上游法排放尾矿,采用自高而下分台阶蠕动排放,修筑防汛缓冲子坝,实行全面防渗与排渗,以及边运行边复垦等有效措施,保证了降雨集中季节以及尾矿冻结融化过程中尾矿库运行的稳定性.%In light of the impact of debris flow on tailings dam incurred by the downstream discharge of tailings below steep slopes with narrow furrows in precipitation-intense seasons in high altitude and cold steep slope tailings dams,an upstream discharge means is applied in which tailings are discharged to steps from high to low,flood-buffe-ring sub-dams are constructed,full-scale seepage prevention and drainage are carried out and reclamation goes hand in hand with the operation. These measures have ensured the operation stability in precipitation-intense seasons and in the process of tailings freezing and melting of tailings dam.

  11. Automated detection of unstable glacier flow and a spectrum of speedup behavior in the Alaska Range

    Science.gov (United States)

    Herreid, Sam; Truffer, Martin

    2016-01-01

    Surge-type glaciers are loosely defined as glaciers that experience periodic alterations between slow and fast flow regimes. Glaciers from a variety of mountain ranges around the world have been classified as surge type, yet consensus of what defines a glacier as surge type has not always been met. A common source of dispute is the lack of a succinct and globally applicable delimiter between a surging and nonsurging glacier. The attempt is often a Boolean classification; however, glacier speedup events can vary significantly with respect to event magnitude, duration, and the fraction of the glacier that participates in the speedup. For this study, we first updated the inventory of glaciers that show flow instabilities in the Alaska Range and then quantified the spectrum of speedup behavior. We developed a new method that automatically detects glaciers with flow instabilities. Our automated results show a 91% success rate when compared to direct observations of speedup events and glaciers that are suspected to display unstable flow based on surface features. Through a combination of observations from the Landsat archive and previously published data, our inventory now contains 36 glaciers that encompass at least one branch exhibiting unstable flow and we document 53 speedup events that occurred between 1936 and 2014. We then present a universal method for comparing glacier speedup events based on a normalized event magnitude metric. This method provides a consistent way to include and quantify the full spectrum of speedup events and allows for comparisons with glaciers that exhibit clear surge characteristics yet have no observed surge event to date. Our results show a continuous spectrum of speedup magnitudes, from steady flow to clearly surge type, which suggests that qualitative classifications, such as "surge-type" or "pulse-type" behavior, might be too simplistic and should be accompanied by a standardized magnitude metric.

  12. Optimization of furrow irrigation mode for summer maize based on weighted grey correlation model%基于加权灰色关联模型优选夏玉米沟灌方式

    Institute of Scientific and Technical Information of China (English)

    汪顺生; 王康三; 刘东鑫; 李欢欢

    2016-01-01

    该文建立加权灰色关联综合评价模型,基于夏玉米耗水量、产量及其构成因素(穗长、穗周长、穗粒数、穗行数、百粒质量和产量)对沟灌方式进行优选。结果表明,同一水分控制下限,无论是产量综合评价,还是耗水及水分利用效率综合评价,宽垄沟灌种植模式的灰色关联综合评价均优于常规沟灌种植模式;其中灌水控制下限为田间持水量的70%(field water holding capacity, FC)的宽垄沟灌种植处理在第2层综合评价中耗水评价虽然位次第3,但产量评价和水分利用效率评价位次第1,在第1层综合评价中灰色关联度最大(0.852),故灌水控制下限为70%(70%FC)最佳;其次为灌水控制下限为60%(60%FC)的宽垄沟灌种植处理,关联度为0.788,60%FC与70%FC二者关联度相差较小。加权灰色关联综合评价模型的评判结果与大田试验结果相吻合。因此,最终方案的最终选定可根据当地水资源状况而定,对于水资源相对丰富地区建议采用W70灌水方式,对于水资源相对匮乏地区建议采用W60灌水方式。研究可为灰色关联度方法在节水灌溉研究中的应用提供参考。%A suitable cultivation mode directly affects the effect of water saving and yield of crops. In order to study the application of the grey correlation model in the research of water saving irrigation, based on water consumption, yield and its components (spike length, ear perimeter, grain number per spike, rows per ear, hundred grain weight, yield) of summer maize, this paper used the improved grey correlation evaluation model to optimize irrigation methods. The test was carried out in North China University of Water Resources and Electric Power located at 34°47′N and 113°46′E and altitude 110.4 m from June 2, 2012 to September 18, 2012. Two kinds of planting modes under furrow irrigation (conventional furrow irrigation and wide ridge and

  13. Furrow Irrigation Management and Design Criteria Using Efficiency Parameters and Simulation Models Criterios para Manejo y Diseño de Riego por Surcos Utilizando Parámetros de Eficiencia y Modelos de Simulación

    Directory of Open Access Journals (Sweden)

    Eduardo A. Holzapfel

    2010-06-01

    Full Text Available This study analyzes the relationship between the variables of furrow irrigation and the irrigation performance parameters, crop yield, and deep percolation as a basis for furrow irrigation design and management. Application efficiency (AE, requirement efficiency (RE, requirement distribution efficiency (RDE, total distribution efficiency (TDE, and furrow irrigation management, operation, and design variables (inflow discharge, furrow length, and irrigation cutoff time were correlated. The relationship between performance irrigation parameters and relative yield was also examined. In addition, environmental aspects related to leaching and runoff were also presented for each of the parameters. Study results indicate that increasing the length of the furrow reduces RE, RDE, and TDE values. However, an increase in inflow discharge and cutoff time increases efficiency. In contrast, an increase in furrow length increases AE while an increase in inflow discharge and cutoff time reduces it. Unlike AE, RE, RDE, and TDE parameters are well-correlated with relative yield. TDE and AE are recommended parameters for the design, management, and operation of furrow irrigation systems, in order to establish good irrigation practices, and to prevent contamination.El presente artículo analiza la relación entre las variables de riego por surcos y los parámetros que determinan la calidad del riego, producción, y percolación profunda como base para el diseño y manejo del riego por surcos. Se ha realizado la correlación entre la eficiencia de aplicación (AE, eficiencia de requerimiento (RE, eficiencia de distribución del requerimiento (RDE, eficiencia de distribución total (TDE, y las variables de manejo, operación y diseño de riego por surcos (caudal, longitud de surco y tiempo de corte de riego. También se ha examinado la relación entre los parámetros que determinan la calidad de riego y la producción relativa. Además, se presentan para cada uno de

  14. 调压井水面面积对水轮机稳定运行的影响%Influence of Water Area of Surge Tank on Stable Operation of Hydraulic Turbine

    Institute of Scientific and Technical Information of China (English)

    黄顺礼

    2000-01-01

    利用汤姆计算调压井水位波动的方程,得到在这个波动过程中水轮机流量的振荡曲线,从而证明调压井水面面积的取值大小影响水轮机的稳定运行,当流量振荡严重时,水轮机就会发生振动。%Presents the oscillating curves for hydraulic turbine flow rate during fluctuation of surge tank water level obtained using Thoma equation, which proves that the effect of water area of surge tank on stable operation of hydraulic turbine is so that hydraulic turbine may vibrate when flow rate flucturates significantly.

  15. A probabilistic storm surge risk model for the German North Sea and Baltic Sea coast

    Science.gov (United States)

    Grabbert, Jan-Henrik; Reiner, Andreas; Deepen, Jan; Rodda, Harvey; Mai, Stephan; Pfeifer, Dietmar

    2010-05-01

    The German North Sea coast is highly exposed to storm surges. Due to its concave bay-like shape mainly orientated to the North-West, cyclones from Western, North-Western and Northern directions together with astronomical tide cause storm surges accumulating the water in the German bight. Due to the existence of widespread low-lying areas (below 5m above mean sea level) behind the defenses, large areas including large economic values are exposed to coastal flooding including cities like Hamburg or Bremen. The occurrence of extreme storm surges in the past like e.g. in 1962 taking about 300 lives and causing widespread flooding and 1976 raised the awareness and led to a redesign of the coastal defenses which provide a good level of protection for today's conditions. Never the less the risk of flooding exists. Moreover an amplification of storm surge risk can be expected under the influence of climate change. The Baltic Sea coast is also exposed to storm surges, which are caused by other meteorological patterns. The influence of the astronomical tide is quite low instead high water levels are induced by strong winds only. Since the exceptional extreme event in 1872 storm surge hazard has been more or less forgotten. Although such an event is very unlikely to happen, it is not impossible. Storm surge risk is currently (almost) non-insurable in Germany. The potential risk is difficult to quantify as there are almost no historical losses available. Also premiums are difficult to assess. Therefore a new storm surge risk model is being developed to provide a basis for a probabilistic quantification of potential losses from coastal inundation. The model is funded by the GDV (German Insurance Association) and is planned to be used within the German insurance sector. Results might be used for a discussion of insurance cover for storm surge. The model consists of a probabilistic event driven hazard and a vulnerability module, furthermore an exposure interface and a financial

  16. Mass Balance Evolution of Black Rapids Glacier, Alaska, 1980–2100, and Its Implications for Surge Recurrence

    OpenAIRE

    Christian Kienholz; Regine Hock; Martin Truffer; Peter Bieniek; Richard Lader

    2017-01-01

    Surge-type Black Rapids Glacier, Alaska, has undergone strong retreat since it last surged in 1936–1937. To assess its evolution during the late Twentieth and Twenty-first centuries and determine potential implications for surge likelihood, we run a simplified glacier model over the periods 1980–2015 (hindcasting) and 2015–2100 (forecasting). The model is forced by daily temperature and precipitation fields, with downscaled reanalysis data used for the hindcasting. A constant climate scenario...

  17. Assessment of surge arrester failure rate and application studies in Hellenic high voltage transmission lines

    Energy Technology Data Exchange (ETDEWEB)

    Christodoulou, C.A.; Fotis, G.P.; Gonos, I.F.; Stathopulos, I.A. [National Technical University of Athens, School of Electrical and Computer Engineering, High Voltage Laboratory, 9 Iroon Politechniou St., Zografou Campus, 157 80 Athens (Greece); Ekonomou, L. [A.S.PE.T.E. - School of Pedagogical and Technological Education, Department of Electrical Engineering Educators, N. Heraklion, 141 21 Athens (Greece)

    2010-02-15

    The use of transmission line surge arresters to improve the lightning performance of transmission lines is becoming more common. Especially in areas with high soil resistivity and ground flash density, surge arresters constitute the most effective protection mean. In this paper a methodology for assessing the surge arrester failure rate based on the electrogeometrical model is presented. Critical currents that exceed arresters rated energy stress were estimated by the use of a simulation tool. The methodology is applied on operating Hellenic transmission lines of 150 kV. Several case studies are analyzed by installing surge arresters on different intervals, in relation to the region's tower footing resistance and the ground flash density. The obtained results are compared with real records of outage rate showing the effectiveness of the surge arresters in the reduction of the recorded failure rate. The presented methodology can be proved valuable to the studies of electric power systems designers intending in a more effective lightning protection, reducing the operational costs and providing continuity of service. (author)

  18. Co-ordination of spark-gap protection with zinc-oxide surge arresters

    Energy Technology Data Exchange (ETDEWEB)

    Haddad, A.; German, D.M.; Waters, R.T. [Cardiff Univ., School of Engineering, Cardiff (United Kingdom); Abdul-Malek, Z. [University of Technology (Malaysia)

    2001-01-01

    Zinc-oxide (ZnO) surge arresters are now well established as a very efficient and reliable form of overvoltage protection against both fast surges, such as those generated by lightning and gas-insulated switchgear, and high-energy surges generated by switching operations and temporary faults on the network. The addition of ZnO surge arresters to existing protection schemes reinforces the system's reliability and the security of supply. The protection characteristics of the parallel configuration formed by arresters and existing spark gaps at distribution voltages are studied. Tests on various spark-gap geometries, with and without surge arresters in parallel, have been carried out to determine breakdown characteristics, probability curves and voltage-time characteristics for different impulse shapes. It is found that the introduction of the arrester in the circuit modifies the prospective impulse which results in the shift of the breakdown characteristics towards higher voltages. A proposed circuit model, based on laboratory test data, is used to simulate such parallel configurations. Good agreement between test and simulated results is obtained. As a result of these tests, it is recommended that gap-sparkover characteristics based on short-tail (about 5{mu}s) impulses are used for insulation co-ordination. The role of parallel airgaps in preserving the arrester energy-rating limits is also discussed. (Author)

  19. Effective Installations Technique of Grounding Conductors for Metal Oxide Surge Arresters

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B.H.; Kang, S.M. [Inha University, Inchon (Korea); Ryu, I.S. [Korea Electric Power Corporation, Seoul (Korea)

    2002-06-01

    This paper deals with the effects of grounding conductors for metal oxide surge arresters. When surge arresters are improperly installed, the results can cause costly damage of electrical equipments. In particular, the route of surge arrester connection is very important because bends and links of leads increase the impedances to lightning surges and tend to nullify the effectiveness of a grounding conductor. Therefore, there is a need to know how effective installation of lightning surge arresters is made in order to control voltage and to absorb energy at high lightning currents. The effectiveness of a grounding conductor and 18 [kV] metal oxide distribution line arresters was experimentally investigated under the lightning and oscillatory impulse voltages. Thus, the results are as follows; (1) The induced voltage of a grounding conductor is drastically not affected by length of a connecting line, but it is very sensitive to types of grounding conductor. (2) The coaxial cable having a low characteristic impedance is suitable as a grounding conductor. (3) It is also clear from these results that bonding the metal raceway enclosing the grounding conductor to the grounding electrode is very effective because of skin effect. (4) The induced voltages of grounding conductors for the oscillatory impulse voltages are approximately twice as large as those for the lightning impulse voltages. (author). 9 refs., 12 figs., 2 tabs.

  20. Parameter sensitivity and uncertainty analysis for a storm surge and wave model

    Science.gov (United States)

    Bastidas, Luis A.; Knighton, James; Kline, Shaun W.

    2016-09-01

    Development and simulation of synthetic hurricane tracks is a common methodology used to estimate hurricane hazards in the absence of empirical coastal surge and wave observations. Such methods typically rely on numerical models to translate stochastically generated hurricane wind and pressure forcing into coastal surge and wave estimates. The model output uncertainty associated with selection of appropriate model parameters must therefore be addressed. The computational overburden of probabilistic surge hazard estimates is exacerbated by the high dimensionality of numerical surge and wave models. We present a model parameter sensitivity analysis of the Delft3D model for the simulation of hazards posed by Hurricane Bob (1991) utilizing three theoretical wind distributions (NWS23, modified Rankine, and Holland). The sensitive model parameters (of 11 total considered) include wind drag, the depth-induced breaking γB, and the bottom roughness. Several parameters show no sensitivity (threshold depth, eddy viscosity, wave triad parameters, and depth-induced breaking αB) and can therefore be excluded to reduce the computational overburden of probabilistic surge hazard estimates. The sensitive model parameters also demonstrate a large number of interactions between parameters and a nonlinear model response. While model outputs showed sensitivity to several parameters, the ability of these parameters to act as tuning parameters for calibration is somewhat limited as proper model calibration is strongly reliant on accurate wind and pressure forcing data. A comparison of the model performance with forcings from the different wind models is also presented.

  1. The physics of debris flows

    Science.gov (United States)

    Iverson, R.M.

    1997-01-01

    Recent advances in theory and experimentation motivate a thorough reassessment of the physics of debris flows. Analyses of flows of dry, granular solids and solid-fluid mixtures provide a foundation for a comprehensive debris flow theory, and experiments provide data that reveal the strengths and limitations of theoretical models. Both debris flow materials and dry granular materials can sustain shear stresses while remaining static; both can deform in a slow, tranquil mode characterized by enduring, frictional grain contacts; and both can flow in a more rapid, agitated mode characterized by brief, inelastic grain collisions. In debris flows, however, pore fluid that is highly viscous and nearly incompressible, composed of water with suspended silt and clay, can strongly mediate intergranular friction and collisions. Grain friction, grain collisions, and viscous fluid flow may transfer significant momentum simultaneously. Both the vibrational kinetic energy of solid grains (measured by a quantity termed the granular temperature) and the pressure of the intervening pore fluid facilitate motion of grains past one another, thereby enhancing debris flow mobility. Granular temperature arises from conversion of flow translational energy to grain vibrational energy, a process that depends on shear rates, grain properties, boundary conditions, and the ambient fluid viscosity and pressure. Pore fluid pressures that exceed static equilibrium pressures result from local or global debris contraction. Like larger, natural debris flows, experimental debris flows of ???10 m3 of poorly sorted, water-saturated sediment invariably move as an unsteady surge or series of surges. Measurements at the base of experimental flows show that coarse-grained surge fronts have little or no pore fluid pressure. In contrast, finer-grained, thoroughly saturated debris behind surge fronts is nearly liquefied by high pore pressure, which persists owing to the great compressibility and moderate

  2. Reduction of the visual impact of overhead transmission line systems through utilisation of line surge arresters as lightning protection

    DEFF Research Database (Denmark)

    Sørensen, Thomas Kjærsgaard; Holbøll, Joachim

    2008-01-01

    in line performance and lightning protection of the nearest substations requires thorough modelling of the new line including all electrical parameters necessary for performance evaluation under all conditions. In this paper, explicit use of line surge arresters as lightning protection on the line...... of the line and the required protection level in substations. The use of line surge arresters gives the possibility to decrease the height of towers thereby improving the visual impression of the overhead line transmission systems. However the usage of line surge arresters will, dependent upon line surge...

  3. Lightning Surge Analysis in 154 kV S/S due to Flashover on the 4 Circuits Tower

    Energy Technology Data Exchange (ETDEWEB)

    Woo, J. W.; Shim, E. B.; Kwak, J. S.; Choi, B. J. [Korea Electric Power Corporation (Korea)

    2000-07-01

    This paper describes the analysis results for the protection of lightning surge at 154 kV substation. We found that the surge arrester is needed at the inlet structure. The maximum overvoltage is about 1,500 kV at the circuit breaker without the surge arrester at the inlet structure. This value can be lower than 600 kV by installing the surge arrester at the inlet structure. In addition to the shield wire should be considered to prevent the shielding failure by the direct lightning stroke. (author). 6 refs., 8 figs.

  4. Parameter identification of ZnO surge arrester models based on genetic algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Bayadi, Abdelhafid [Laboratoire d' Automatique de Setif, Departement d' Electrotechnique, Faculte des Sciences de l' Ingenieur, Universite Ferhat ABBAS de Setif, Route de Bejaia Setif 19000 (Algeria)

    2008-07-15

    The correct and adequate modelling of ZnO surge arresters characteristics is very important for insulation coordination studies and systems reliability. In this context many researchers addressed considerable efforts to the development of surge arresters models to reproduce the dynamic characteristics observed in their behaviour when subjected to fast front impulse currents. The difficulties with these models reside essentially in the calculation and the adjustment of their parameters. This paper proposes a new technique based on genetic algorithm to obtain the best possible series of parameter values of ZnO surge arresters models. The validity of the predicted parameters is then checked by comparing the predicted results with the experimental results available in the literature. Using the ATP-EMTP package, an application of the arrester model on network system studies is presented and discussed. (author)

  5. Stabilization of gas-filled surge arrester’s characteristics by use of ionizing radiation

    Directory of Open Access Journals (Sweden)

    Brajović Dragan V.

    2012-01-01

    Full Text Available This paper investigates the stabilization of electrical discharges in gases by means of external ionizing radiation. Discharges in a gas-filled surge arrester model were studied in both passive and active regimes of the device. An originally developed model of the gas-filled surge arrester was used. Gas pressure and the interelectrode gap were the variable parameters in our measurements. Applied radiation types included α-particles, γ-rays, X-rays, and neutrons. Measurements were performed under highly controlled laboratory conditions. The combined measurement uncertainty of the applied procedure was estimated as being under the 5% level. The results obtained are followed by a theoretical explanation. The crucial result is the conclusion that ionizing radiation does not necessarily degrade the gas-filled surge arrester’s functionality but that it, rather, improves it under certain conditions.

  6. Development of an Electro–Thermal Model for ZnO Surge Arrester Under Contamination

    Directory of Open Access Journals (Sweden)

    E. Melgoza–Vázquez

    2010-01-01

    Full Text Available An electro–thermal model for a Zinc Oxide (ZnO surge arrester under contamination tests is presented. The model is based in three sub–models: electrical, thermal and contamination, which interact in order to obtain the surge arrester performance under contamination tests. The electrical model is obtained from measurements and is based on a capacitance and a non–linear resistor. The thermal model takes into account the heat generated and dissipated by the column of varistors and its surroundings. The contamination is represented by a dynamic impedance obtained from measurements in the arrester column during contamination tests. The full model is validated by calculating the temperature increase during contamination tests carried out in a two units ZnO surge arrester, class 190 kV. Finally, the results of the effect of several design and construction parameters in the voltage and temperature distribution in the arrester columns during contamination tests are presented.

  7. The cool surge following flux emergence in a radiation-MHD experiment

    CERN Document Server

    Nóbrega-Siverio, D; Martínez-Sykora, J

    2016-01-01

    Cool and dense ejections, typically H$_{\\alpha}$ surges, often appear alongside EUV or X-Ray coronal jets as a result of the emergence of magnetized plasma from the solar interior. Idealized numerical experiments explain those ejections as being indirectly associated with the magnetic reconnection taking place between the emerging and preexisting systems. However, those experiments miss basic elements that can importantly affect the surge phenomenon. In this paper we study the cool surges using a realistic treatment of the radiation transfer and material plasma properties. To that end, the Bifrost code is used, which has advanced modules for the equation of state of the plasma, photospheric and chromospheric radiation transfer, heat conduction and optically thin radiative cooling. We carry out a 2.5D experiment of the emergence of magnetized plasma through (meso)granular convection cells and the low atmosphere to the corona. Through detailed Lagrange tracing, we study the formation and evolution of the cool e...

  8. Google Earth-based dynamic visualization system for storm surge flood routing

    Institute of Scientific and Technical Information of China (English)

    Liu Donghai; Wang Qian; Zuo Wentao

    2013-01-01

    To describe the dynamic process of flood routing intuitively and realistically when storm surge disaster occurs,a method for ArcGIS data and Google Earth (GE) data integration is proposed,which realizes the impor-ting and integrating of basic geographic information into GE. Based on SketchUp and AutoCAD software,three-dimension (3D) visualization of seawall and other tidal defense structures is achieved. By employing Microsoft Foundation Class Library (MFC),the related system modules and storm surge flood routing dynamic visualization system are developed. Therefore,dynamic visualization of flood routing process and interactive query of sub-merged area and inundated depth are implemented. A practical application case study of Tianjin Binhai New Area provides decision-making support for coastal seawall planning and storm surge disaster prevention and reduction.

  9. Dynamic Model of Centrifugal Compressor for Prediction of Surge Evolution and Performance Variations

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Mooncheong; Han, Jaeyoung; Yu, Sangseok [Chungnam National Univ., Daejeon (Korea, Republic of)

    2016-05-15

    When a control algorithm is developed to protect automotive compressor surges, the simulation model typically selects an empirically determined look-up table. However, it is difficult for a control oriented empirical model to show surge characteristics of the super charger. In this study, a dynamic supercharger model is developed to predict the performance of a centrifugal compressor under dynamic load follow-up. The model is developed using Simulink® environment, and is composed of a compressor, throttle body, valves, and chamber. Greitzer’s compressor model is used, and the geometric parameters are achieved by the actual supercharger. The simulation model is validated with experimental data. It is shown that compressor surge is effectively predicted by this dynamic compressor model under various operating conditions.

  10. Experimental Study on Active Control of Surge in a Centrifugal Compression System

    Directory of Open Access Journals (Sweden)

    Nie Chaoqun

    2000-01-01

    Full Text Available An experimental study has been carried out on the active control of surge in a centrifugal compression system. With a computerized on-line control scheme, the surge phenomenon is suppressed and the stable operating range of the system is extended. In order to design the active control scheme and choose the desired parameters of the control system inputs, special emphases have been placed on the development of surge inception and the nonlinear interaction between the system and the actuator. By use of the method designed in the present work, the results of active control onsurge have been demonstrated for the different B parameters, different prescribed criteria and different control frequencies.

  11. Protection of New York City Urban Fabric With Low-Cost Textile Storm Surge Barriers

    CERN Document Server

    Bolonkin, Alexander

    2007-01-01

    Textile storm surge barriers, sited at multiple locations, are literally extensions of the city world famous urban fabric - another manifestation of the dominance of the City over local Nature. Textile Storm Surge Barriers (TSSB) are intended to preserve the City from North Atlantic Ocean hurricanes that cause sea waves impacting the densely populated and high-value real estate, instigating catastrophic, and possibly long-term, infrastructure and monetary losses. Complicating TSSB installation macroproject planning is the presence of the Hudson and other rivers, several small tidal straits, future climate change and other factors. We conclude that TSSB installations made of homogeneous construction materials are worthwhile investigating because they may be less expensive to build, and more easily replaced following any failure, than concrete and steel storm surge barriers, which are also made of homogeneous materials. We suppose the best macroproject outcome will develop in the perfect Macro-engineering plann...

  12. On Active Surge Control of Compression Systems via Characteristic Linearization and Model Nonlinearity Cancellation

    Directory of Open Access Journals (Sweden)

    Yohannes S.M. Simamora

    2014-09-01

    Full Text Available A simple approach of active surge control of compression systems is presented. Specifically, nonlinear components of the pressure ratio and rotating speed states of the Moore-Greitzer model are transferred into the input vectors. Subsequently, the compressor characteristic is linearized into two modes, which describe the stable region and the unstable region respectively. As a result, the system’s state and input matrices both appear linear, to which linear realization and analysis are applicable. A linear quadratic regulator plus integrator is then chosen as closed-loop controller. By simulation it was shown that the modified model and characteristics can describe surge behavior, while the closed-loop controller can stabilize the system in the unstable operating region. The last-mentioned was achieved when massflow was 5.38 per cent less than the surge point.

  13. A parabolic model of drag coefficient for storm surge simulation in the South China Sea.

    Science.gov (United States)

    Peng, Shiqiu; Li, Yineng

    2015-10-26

    Drag coefficient (Cd) is an essential metric in the calculation of momentum exchange over the air-sea interface and thus has large impacts on the simulation or forecast of the upper ocean state associated with sea surface winds such as storm surges. Generally, Cd is a function of wind speed. However, the exact relationship between Cd and wind speed is still in dispute, and the widely-used formula that is a linear function of wind speed in an ocean model could lead to large bias at high wind speed. Here we establish a parabolic model of Cd based on storm surge observations and simulation in the South China Sea (SCS) through a number of tropical cyclone cases. Simulation of storm surges for independent Tropical cyclones (TCs) cases indicates that the new parabolic model of Cd outperforms traditional linear models.

  14. Winter speed-up of quiescent surge-type glaciers in Yukon, Canada

    Science.gov (United States)

    Abe, T.; Furuya, M.

    2015-06-01

    Glacier surges often initiate in winter, but the mechanism remains unclear in contrast to the well-known summer speed-up at normal glaciers. To better understand the mechanism, we used radar images to examine spatial-temporal changes in the ice velocity of surge-type glaciers near the border of Alaska and the Yukon, focusing on their quiescent phase. We found significant accelerations in the upstream region from autumn to winter, regardless of surging episodes. Moreover, the winter speed-up propagated from upstream to downstream. Given the absence of surface meltwater input in winter, we suggest the presence of water storage near the base that does not directly connect to the surface, yet can promote basal sliding through increased water pressure. Our findings have implications for the modelling of glacial hydrology in winter, which may help us better understand glacier dynamics.

  15. Winter speed-up of quiescent surge-type glaciers in Yukon, Canada

    Directory of Open Access Journals (Sweden)

    T. Abe

    2014-05-01

    Full Text Available Glacier surge is known to often initiate in winter, but the mechanisms remain unclear in light of the summer speed-up at normal glaciers. We examined spatial-temporal changes in the ice velocity of surge-type glaciers near the border of Alaska and Yukon, and found significant upstream accelerations from fall to winter, regardless of surging episodes. Moreover, whereas the summer speed-up was observed downstream, the winter speed-up propagated from upstream to downglacier. Given the absence of upstream surface meltwater input in winter, we speculate the presence of water storages near the base that do not directly connect to the surface but can promote basal sliding through increased water pressure as winter approaches. Our findings have implications for modeling of glacial hydrology in winter time, and its link to glacier dynamics and subglacial erosion.

  16. Quantification of Storm Surge Using A Python-based ArcGIS Toolbox

    Science.gov (United States)

    Gao, S.; Siverd, C. G.; Bilskie, M. V.; Hagen, S. C.; Alizad, K.

    2016-12-01

    Geographic Information System (GIS) technology allows the organization, manipulation, analysis, and visualization of spatial data (Fischer, 2010). Although GIS provides some operations for spatial analysis, the methods are often only partially implemented and can be difficult to find and use effectively (Rigol-Sanchez et al., 2015). For coastal researchers, development of automated GIS tools is essential to efficiently analyze coastal flood risk from hurricanes. An adaptive GIS toolbox, Quantitative Surge Analysis Tool (QSAT), was developed and implements ArcGIS software and Python scripts to quantify attributes of hurricane storm surge (e.g., average water surface elevation). The python script provides a way to allow researchers to reduce the amount of time spent developing common solutions (Etherington, 2010) and repeating manual operations. The QSAT contains tools that run in the ArcGIS program. These tools compute average water surface elevation, average inundation depth, inundated area, total surge volume, percent of land inundated, and retention time for a given polygonal area. A new shapefile is created with a detail attribute table containing the various surge quantities. The toolbox is designed to directly read data files produced by an ADCIRC storm surge simulation as well as a polygon shapefile defining the areas of interest. The functionality of the QSAT toolbox was tested using Hydrologic Unit Code 12 (HUC 12) polygons of coastal Louisiana and ADCIRC model results from a simulation of Hurricane Gustav. The QSAT aids a streamlined transition of surge quantities across a local medium (i.e. HUC 12s) to better inform stakeholders and lead to improved regional and local decisions.

  17. Automating Flood Hazard Mapping Methods for Near Real-time Storm Surge Inundation and Vulnerability Assessment

    Science.gov (United States)

    Weigel, A. M.; Griffin, R.; Gallagher, D.

    2015-12-01

    Storm surge has enough destructive power to damage buildings and infrastructure, erode beaches, and threaten human life across large geographic areas, hence posing the greatest threat of all the hurricane hazards. The United States Gulf of Mexico has proven vulnerable to hurricanes as it has been hit by some of the most destructive hurricanes on record. With projected rises in sea level and increases in hurricane activity, there is a need to better understand the associated risks for disaster mitigation, preparedness, and response. GIS has become a critical tool in enhancing disaster planning, risk assessment, and emergency response by communicating spatial information through a multi-layer approach. However, there is a need for a near real-time method of identifying areas with a high risk of being impacted by storm surge. Research was conducted alongside Baron, a private industry weather enterprise, to facilitate automated modeling and visualization of storm surge inundation and vulnerability on a near real-time basis. This research successfully automated current flood hazard mapping techniques using a GIS framework written in a Python programming environment, and displayed resulting data through an Application Program Interface (API). Data used for this methodology included high resolution topography, NOAA Probabilistic Surge model outputs parsed from Rich Site Summary (RSS) feeds, and the NOAA Census tract level Social Vulnerability Index (SoVI). The development process required extensive data processing and management to provide high resolution visualizations of potential flooding and population vulnerability in a timely manner. The accuracy of the developed methodology was assessed using Hurricane Isaac as a case study, which through a USGS and NOAA partnership, contained ample data for statistical analysis. This research successfully created a fully automated, near real-time method for mapping high resolution storm surge inundation and vulnerability for the

  18. A model study of Abrahamsenbreen, a surging glacier in northern Spitsbergen

    Directory of Open Access Journals (Sweden)

    J. Oerlemans

    2014-11-01

    Full Text Available The climate sensitivity of Abrahamsenbreen, a 20 km long surge-type glacier in northern Spitsbergen, is studied with a simple glacier model. A scheme to describe the surges is included, which makes it possible to account for the effect of surges on the total mass budget of the glacier. A climate reconstruction back to AD 1300, based on ice-core data from Lomonosovfonna and climate records from Longyearbyen, is used to drive the model. The model is calibrated by requesting that it produces the correct Little Ice Age maximum glacier length and simulates the observed magnitude of the 1978-surge. Abrahamsenbreen is strongly out of balance with the current climate. If climatic conditions will remain as they were for the period 1989–2010, the glacier will ultimately shrink to a length of about 4 km (but this will take hundreds of years. For a climate change scenario involving a 2 m yr−1 rise of the equilibrium line from now onwards, we predict that in the year 2100 Abrahamsenbreen will be about 12 km long. The main effect of a surge is to lower the mean surface elevation and to increase the ablation area, thereby causing a negative perturbation of the mass budget. We found that the occurrence of surges leads to a somewhat stronger retreat of the glacier in a warming climate. Because of the very small bed slope, Abrahamsenbreen is sensitive to small perturbations in the equilibrium-line altitude E. For a decrease of E of only 160 m, the glacier would steadily grow into the Woodfjorddalen until after 2000 years it would reach the Woodfjord and calving could slow down the advance.

  19. A high resolution study of a hurricane storm surge and inundation in Veracruz, Mexico

    Science.gov (United States)

    Díaz García, Ovel; Zavala Hidalgo, Jorge; Douillet, Pascal

    2014-05-01

    Veracruz is the most populated city along the Mexican shoreline of the Gulf of Mexico and also is the country's largest commercial port. In recent years the city has been affected by hurricanes of medium intensity that have provoked human casualties, property damaged and economic loss. Two of the most recent events were hurricane Karl (2010), which caused a storm surge and severe flooding, and hurricane Ernesto (2012). The purpose of this work is to study, based on high-resolution numerical simulations, scenarios of storm surge flooding using state-of-the-art open source numerical models: the Weather, Research and Forecasting (WRF), and the coupled models ADvanced CIRCulation (ADCIRC) and Simulating WAves Nearshore (SWAN) for weather and storm surge hindcast, respectively. We also use topography high resolution data from LIDAR and bathymetry from GEBCO 30", the Mexican Navy and nautical charts from Electrical Federal Commission. We present the validation of the models evaluating several statistical parameters against measurements from Acoustic Data Current Profilers, pressure sensors, tide gauge and meteorological stations for these events. In the case of hurricane Karl, it made landfall 15 km north of Veracruz City, reducing the maximum surge along the city shoreline. The hurricane Ernesto made landfall 200 km southeast of the city, too far to have a significant impact. We did some numerical experiments slightly changing the trajectory, reported by the best track data, for these two hurricanes with the purpose of evaluating storm surge scenarios. The results shows that the worst storm surge cases were when the tracks of this hurricanes made landfall south of the city in the range of 30 to 60 km.

  20. Dynamics of wave-current-surge interactions in Lake Michigan: A model comparison

    Science.gov (United States)

    Mao, Miaohua; Xia, Meng

    2017-02-01

    Wave, storm surge dynamics, and wave-current-surge interactions (WCSI) were investigated by applying a pair of unstructured-grid-based models to Lake Michigan under two strong wind events. The effects of wind field sources, wind drag coefficient bulk formula, and parameterizations of the bottom friction term were explored to understand lake dynamics. Two wave models were calibrated by using alternative wave physics settings under the 2011 northeasterly wind event. Forced by the southwesterly wind event in 2013, the calibrated models using the atmosphere-ocean fully coupled Climate Forecast System Version 2 wind field were further validated. It is found that the northwesterly winds induced 0.57 m setup near the southwestern coast, whereas the southwesterly winds produced 0.28 m setup and -0.43 m setdown near the northern and southwestern coasts, respectively. The WCSI mostly influence waves and storm surge in shallow-water areas near coasts and islands through depth-induced breaking, current-induced frequency shift and refraction, and wave-induced setup/setdown through wave radiation stress. Owing to the adoption of different discretization algorithms and bottom friction formulations, the modeled storm surge and waves exhibit some variation between the paired models. Even though the storm surge difference with and without WCSI is smaller than that between the two WCSI-coupled models, both circulation models adopt WCSI considering their consistent improvement on model accuracy under both wind events. The analysis of water transport indicates that wind speed, direction, and coastal geometry and bathymetry are also important factors in storm surge.

  1. The Propagation of a Surge Front on Bering Glacier, Alaska, 2001-2011

    Science.gov (United States)

    Turrin, James; Forster, Richard R.; Larsen, Chris; Sauber, Jeanne

    2013-01-01

    Bering Glacier, Alaska, USA, has a 20 year surge cycle, with its most recent surge reaching the terminus in 2011. To study this most recent activity a time series of ice velocity maps was produced by applying optical feature-tracking methods to Landsat-7 ETM+ imagery spanning 2001-11. The velocity maps show a yearly increase in ice surface velocity associated with the down-glacier movement of a surge front. In 2008/09 the maximum ice surface velocity was 1.5 plus or minus 0.017 kilometers per a in the mid-ablation zone, which decreased to 1.2 plus or minus 0.015 kilometers per a in 2009/10 in the lower ablation zone, and then increased to nearly 4.4 plus or minus 0.03 kilometers per a in summer 2011 when the surge front reached the glacier terminus. The surge front propagated down-glacier as a kinematic wave at an average rate of 4.4 plus or minus 2.0 kilometers per a between September 2002 and April 2009, then accelerated to 13.9 plus or minus 2.0 kilometers per a as it entered the piedmont lobe between April 2009 and September 2010. Thewave seems to have initiated near the confluence of Bering Glacier and Bagley Ice Valley as early as 2001, and the surge was triggered in 2008 further down-glacier in the mid-ablation zone after the wave passed an ice reservoir area.

  2. Long Hard Road: Volume II -- NCO Experiences in the Surge

    Science.gov (United States)

    2009-10-01

    prove the flow of reports and analysis from the Commander in the field, imple- ment them to assist the commander in analyzing what is happening in his...have added numerous acronyms to our military lingo . For the purposes of brevity and clarity, this paper will focus on one: Forward Operating Base...terrain platoon, which was located in Heidelberg under V Corps. The unit provided topographic informa- tion through terrain and geospatial analysis

  3. Surge motion of an ice floe in waves: comparison of theoretical and experimental models

    CERN Document Server

    Meylan, Michael; Bennetts, Luke; French, Benjamin; Thomas, Giles

    2014-01-01

    A theoretical model and an experimental model of surge motions of an ice floe due to regular waves are presented. The theoretical model is a modified version of Morrison's equation, valid for small floating bodies. The experimental model is implemented in a wave basin at scale 1:100, using a thin plastic disk to model the floe. The processed experimental data displays a regime change in surge amplitude when the incident wavelength is approximately twice the floe diameter. It is shown that the theoretical model is accurate in the large wavelength regime, but highly inaccurate for the small wavelength regime.

  4. Implementation and application of a nested numerical storm surge forecast model in the East China Sea

    Institute of Scientific and Technical Information of China (English)

    于福江; 张占海

    2002-01-01

    A nested numerical storm surge forecast model for the East China Sea is developed. A one-way relaxing nest method is used to exchange the information between coarse grid and fine grid. In the inner boundary of the fine grid model a transition area is set up to relax the forecast variables. This ensures that the forecast variables of the coarse model may transit to those of fine grid gradually, which enhances the model stability. By using this model, a number of hindcasts and forecast are performed for six severe storm surges caused by tropical cyclones in the East China Sea. The results show good agreement with the observations.

  5. Possible management of near shore nonlinear surging waves through bottom boundary conditions

    Science.gov (United States)

    Mukherjee, Abhik; Janaki, M. S.; Kundu, Anjan

    2017-03-01

    We propose an alternative way for managing near shore surging waves, including extreme waves like tsunamis, going beyond the conventional passive measures like the warning system. We study theoretically the possibility of influencing the nonlinear surface waves through a leakage boundary effect at the bottom. It has been found through analytic result, that the controlled leakage at the bottom might regulate the amplitude of the surface solitary waves. This could lead to a possible decay of the surging waves to reduce its hazardous effects near the shore. Our theoretical results are estimated by applying it to a real coastal bathymetry of the Bay of Bengal in India.

  6. Effects of seismic surge waves and implications for moraine-dammed lake outburst

    Science.gov (United States)

    Du, Cui; Yao, Lingkan; Huang, Yidan; Yan, Jiahong; Shakya, Subhashsagar

    2016-09-01

    Moraine dams usually collapse due to overtopping by the surge wave in the dammed lake, and the surge wave is most likely caused by an earthquake. The seismic water wave (SWW) is a major factor causing the dam to break in the earthquake zone. This paper focused on the SWW by model experiments with a shaking water tank under conditions of various water depths, seismic waves, and peak ground accelerations. Two empirical equations were obtained for estimating maximal wave height for the low and high frequency, respectively. Finally, we present the application of the empirical equations on Midui Glacier Lake in Tibet plateau.

  7. Analysis of vehicle surge. Relationship with the coefficient of variation in combustion of engine; Sharyo surge no kaiseki. Engine nensho hendoritsu tono kankei

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, H. [Subaru Research Center Co. Ltd., Tokyo (Japan)

    1998-05-01

    Leaning of great magnitude and increase in EGR rate are being moved forward to reduce fuel consumption and improve exhaust gas emission, where variation in combustion is one of the important evaluation items. No studies can be found to date, which express the relationship between variation in combustion and vehicle surge as a specific numerical function including vehicle characteristics. Forward and rearward vehicle acceleration may be expressed by root mean square (RMS) of square mean of instantaneous acceleration. The Parseval`s theorem was used to convert the forward and rearward vehicle acceleration and time function of engine torque into a frequency function, and to perform an analysis in the frequency region. It was made clear that, when engine rotation speed is 1200 rpm or higher, or if there is no torque deviation between cylinders, vehicle surge can be expressed as the vehicle power characteristic value, the drivetrain characteristic value, the indicated mean effective pressure, the torque shape coefficient, the surge rate, and the product of the combustion variation coefficient. The drivetrain characteristic value could be said a dynamic total reduction gear ratio, and is a function of the drivetrain factors, which are largely affected especially by the mechanical loss factor of tires and suspension systems. 6 refs., 7 figs., 2 tabs.

  8. Improvements of Storm Surge Modelling in the Gulf of Venice with Satellite Data: The ESA Due Esurge-Venice Project

    Science.gov (United States)

    De Biasio, F.; Bajo, M.; Vignudelli, S.; Papa, A.; della Valle, A.; Umgiesser, G.; Donlon, C.; Zecchetto, S.

    2016-08-01

    Among the most detrimental natural phenomena, storm surges heavily endanger the environment, the economy and the everyday life of sea-side countries and coastal zones. Considering that 120.000.000 people live in the Mediterranean area, with additional 200.000.000 presences in Summer for tourism purposes, the correct prediction of storm surges is crucial to avoid fatalities and economic losses. Earth Observation (EO) can play an important role in operational storm surge forecasting, yet it is not widely diffused in the storm surge community. In 2011 the European Space Agency (ESA), through its Data User Element (DUE) programme, financed two projects aimed at encouraging the uptake of EO data in this sector: eSurge and eSurge-Venice (eSV). The former was intended to address the issues of a wider users' community, while the latter was focused on a restricted geographical area: the northern Adriatic Sea and the Gulf of Venice. Among the objectives of the two projects there were a number of storm surge hindcast experiments using satellite data, to demonstrate the improvements on the surge forecast brought by EO. We report here the results of the hindcast experiments of the eSV project. They were aimed to test the sensitivity of a storm surge model to a forcing wind field modified with scatterometer data in order to reduce the bias between simulated and observed winds. Hindcast experiments were also performed to test the response of the storm surge model to the assimilation, with a dual 4D-Var system, of satellite altimetry observations as model errors of the initial state of the sea surface level. Remarkable improvements on the storm surge forecast have been obtained for what concerns the modified model wind forcing. Encouraging results have been obtained also in the assimilation experiments.

  9. Adapting NEMO for use as the UK operational storm surge forecasting model

    Science.gov (United States)

    Furner, Rachel; Williams, Jane; Horsburgh, Kevin; Saulter, Andrew

    2016-04-01

    The United Kingdom is an area vulnerable to damage due to storm surges, particularly the East Coast which suffered losses estimated at over £1 billion during the North Sea surge event of the 5th and 6th December 2013. Accurate forecasting of storm surge events for this region is crucial to enable government agencies to assess the risk of overtopping of coastal defences so they can respond appropriately, minimising risk to life and infrastructure. There has been an operational storm surge forecast service for this region since 1978, using a numerical model developed by the National Oceanography Centre (NOC) and run at the UK Met Office. This is also implemented as part of an ensemble prediction system, using perturbed atmospheric forcing to produce an ensemble surge forecast. In order to ensure efficient use of future supercomputer developments and to create synergy with existing operational coastal ocean models the Met Office and NOC have begun a joint project transitioning the storm surge forecast system from the current CS3X code base to a configuration based on the Nucleus for European Modelling of the Ocean (NEMO). This work involves both adapting NEMO to add functionality, such as allowing the drying out of ocean cells and changes allowing NEMO to run efficiently as a two-dimensional, barotropic model. As the ensemble surge forecast system is run with 12 members 4 times a day computational efficiency is of high importance. Upon completion this project will enable interesting scientific comparisons to be made between a NEMO based surge model and the full three-dimensional baroclinic NEMO based models currently run within the Met Office, facilitating assessment of the impact of baroclinic processes, and vertical resolution on sea surface height forecasts. Moving to a NEMO code base will also allow many future developments to be more easily used within the storm surge model due to the wide range of options which currently exist within NEMO or are planned for

  10. Effects of plastic film and ridge-furrow cropping patterns on growth and yield of potato in semiarid areas%沟垄覆膜栽培对旱作马铃薯生长及产量的影响

    Institute of Scientific and Technical Information of China (English)

    代海林; 秦舒浩; 张俊莲; 王蒂; 王春林; 陈龙

    2012-01-01

    以当地主栽品种“新大坪”为试验材料,研究了不同沟垄覆膜种植模式对旱作马铃薯生长和产量的影响.结果表明:沟垄覆膜种植能显著提高马铃薯根际的温度、株高、开展度、主根长以及相对生长率(RGR).与传统平畦不覆膜(T1)相比,平畦覆膜(T2)、全膜双垄沟播(T3)、全膜双垄垄播(T4)、半膜膜侧种植(T5)和半膜沟垄垄播(T6)种植分别增产36.29%、59.68%、60.49%、47.58%和45.97%,其中T3和T4的产量最高.沟垄覆膜种植有利于马铃薯产量性状的改善,提高了大薯率和中薯率总和,其中以全膜双垄垄播(T4)最为显著.在该区采用全膜双垄垄播(T4)最有利于马铃薯的生长及产量性状的提高.%"Xin Daping was used as test materials to study the effects of plastic film and ridge-furrow cropping patterns on growth and yield of potato. The results showed that the ground temperature,plant height,the crown width,length of vertical roots and relative growth rate (RGR) of potato increased significantly by ridge-furrow and film cropping patterns. Compared to the traditional flat stretch coating (Tl) ,the yield of the coated flat stretch (T2) ,the whole film double furrow sowing (T3) ,the whole film double ridge broadcast (T4) ,the semimembranosus film side planting (T5) and half-film ridge and furrow ridge sowing (T6) increased by 36.29% ,60.49% ,59.68% ,47.58% ,45.97% ,respectively . The yield increase of T4 and T3 was the highest. All the plastic mulched and ridge-furrow cropping patterns improved yield components of potato. Sum of big and middle tuber rates,tuber number per plant and tuber yield per plant under T4 and T3 were higher than that of the others,whereas green tuber rate,belt tuber rate under T4 and T3 were lower than that of the others. Therefore,the ridge-furrow and film cropping patterns,especially T4,were good cropping patterns for growth and high yield of potato in this area.

  11. Improving the Resilience of Major Ports and Critical Supply Chains to Extreme Coastal Flooding: a Combined Artificial Neural Network and Hydrodynamic Simulation Approach to Predicting Tidal Surge Inundation of Port Infrastructure and Impact on Operations.

    Science.gov (United States)

    French, J.

    2015-12-01

    Ports are vital to the global economy, but assessments of global exposure to flood risk have generally focused on major concentrations of population or asset values. Few studies have examined the impact of extreme inundation events on port operation and critical supply chains. Extreme water levels and recurrence intervals have conventionally been estimated via analysis of historic water level maxima, and these vary widely depending on the statistical assumptions made. This information is supplemented by near-term forecasts from operational surge-tide models, which give continuous water levels but at considerable com