WorldWideScience

Sample records for high-amplitude kinoshita meandering

  1. Numerical modeling of dune progression in a high amplitude meandering channel

    Science.gov (United States)

    Laboratory experiments carried out by Abad and Garcia (2009) in a high-amplitude Kinoshita meandering channel show bed morphodynamics to comprise steady (local scour and deposition) and unsteady (migrating bedforms) components. The experiments are replicated with a numerical model. The sediment tran...

  2. Tidal meanders

    Science.gov (United States)

    Marani, Marco; Lanzoni, Stefano; Zandolin, Diego; Seminara, Giovanni; Rinaldo, Andrea

    2002-11-01

    Observational evidence is presented on the geometry of meandering tidal channels evolved within coastal wetlands characterized by different tidal, hydrodynamic, topographic, vegetational and ecological features. New insight is provided on the geometrical properties of tidal meanders, with possible dynamic implications on their evolution. In particular, it is shown that large spatial gradients of leading flow rates induce important spatial variabilities of meander wavelengths and widths, while their ratio remains remarkably constant in the range of scales of observation. This holds regardless of changes in width and wavelength up to two orders of magnitude. This suggests a locally adapted evolution, involving the morphological adjustment to the chief landforming events driven by local hydrodynamics. The spectral analysis of local curvatures reveals that Kinoshita's model curve does not fit tidal meanders due to the presence of even harmonics, in particular the second mode. Geometric parameters are constructed that are suitable to detect possible geomorphic signatures of the transitions from ebb- to flood-dominated hydrodynamics, here related to the skewness of the tidal meander. Trends in skewness, however, prove elusive to measure and fail to show detectable patterns. We also study comparatively the spatial patterns of evolution of the ratios of channel width to depth, and the ratio of width to local radius of curvature. Interestingly, the latter ratio exhibits consistency despite sharp differences in channel incision. Since the degree of incision, epitomized by the width-to-depth ratio, responds to the relevant erosion and migrations mechanisms and is much sensitive to vegetation and sediment properties, it is noticeable that we observe a great variety of landscape carving modes and yet recurrent planar features like constant width/curvature and wavelength/width ratios.

  3. High Amplitude Secondary Mass Drive

    Energy Technology Data Exchange (ETDEWEB)

    DYCK,CHRISTOPHER WILLIAM; ALLEN,JAMES J.; HUBER,ROBERT JOHN; SNIEGOWSKI,JEFFRY J.

    2000-07-06

    In this paper we describe a high amplitude electrostatic drive for surface micromachined mechanical oscillators that may be suitable for vibratory gyroscopes. It is an advanced design of a previously reported dual mass oscillator (Dyck, et. al., 1999). The structure is a 2 degree-of-freedom, parallel-plate driven motion amplifier, termed the secondary mass drive oscillator (SMD oscillator). During each cycle the device contacts the drive plates, generating large electrostatic forces. Peak-to-peak amplitudes of 54 {micro}m have been obtained by operating the structure in air with an applied voltage of 11 V. We describe the structure, present the analysis and design equations, and show recent results that have been obtained, including frequency response data, power dissipation, and out-of- plane motion.

  4. Iowa's Sovereign Meandered Rivers

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This data set depicts Iowa's Meandered Rivers. These rivers are deemed sovereign land & therefore require any person wishing to conduct construction activities...

  5. Dynamic wake meandering modeling

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, Gunner C.; Aagaard Madsen, H.; Bingoel, F. (and others)

    2007-06-15

    We present a consistent, physically based theory for the wake meandering phenomenon, which we consider of crucial importance for the overall description of wind turbine loadings in wind farms. In its present version the model is confined to single wake situations. The model philosophy does, however, have the potential to include also mutual wake interaction phenomenons. The basic conjecture behind the dynamic wake meandering model is that wake transportation in the atmospheric boundary layer is driven by the large scale lateral- and vertical turbulence components. Based on this conjecture a stochastic model of the downstream wake meandering is formulated. In addition to the kinematic formulation of the dynamics of the 'meandering frame of reference', models characterizing the mean wake deficit as well as the added wake turbulence, described in the meandering frame of reference, are an integrated part the model complex. For design applications, the computational efficiency of wake deficit prediction is a key issue. Two computationally low cost models are developed for this purpose. The character of the added wake turbulence, generated by the up-stream turbine in the form of shed and trailed vorticity, has been approached by analytical as well as by numerical studies. The dynamic wake meandering philosophy has been verified by comparing model predictions with extensive full-scale measurements. These comparisons have demonstrated good agreement, both qualitatively and quantitatively, concerning both flow characteristics and turbine load characteristics. Contrary to previous attempts to model wake loading, the dynamic wake meandering approach opens for a unifying description in the sense that turbine power and load aspects can be treated simultaneously. This capability is a direct and attractive consequence of the model being based on the underlying physical process, and it potentially opens for optimization of wind farm topology, of wind farm operation as

  6. Dynamic wake meandering modeling

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Madsen Aagaard, Helge; Bingöl, Ferhat;

    , are an integrated part the model complex. For design applications, the computational efficiency of wake deficit prediction is a key issue. Two computationally low cost models are developed for this purpose. The character of the added wake turbulence, generated by the up-stream turbine in the form of shed......We present a consistent, physically based theory for the wake meandering phenomenon, which we consider of crucial importance for the overall description of wind turbine loadings in wind farms. In its present version the model is confined to single wake situations. The model philosophy does, however......, have the potential to include also mutual wake interaction phenomenons. The basic conjecture behind the dynamic wake meandering model is that wake transportation in the atmospheric boundary layer is driven by the large scale lateral- and vertical turbulence components. Based on this conjecture...

  7. Geomorphology of Martian meanders

    Science.gov (United States)

    Gregoire-Mazzocco, H.; Stepinski, T.; McGovern, P.; Lanzoni, S.; Marani, M.; Rinaldo, A.

    2005-12-01

    Morphological features of meandering landforms observed on the surface of Mars are computed and discussed. The relevance of the study pertains potentially useful hypotheses for the understanding of the evolution of Mars. Materials are digital images taken from the Mars Orbiter Laser Altimer (MOLA) and from the Viking orbiter. The methods of morphological analysis derive from tool employed in the analysis of channeled landforms, in particular tidal ones, where the unit of information (i.e. the elementary pixel) is considerably smaller than the size of the channels. The results obtained concern the physical characterization of martian meanders, including the evolution in space of widths, wavelengths and curvatures and their spectra. Evidence for a narrow distribution of sinuosities (possibly a proxy of age of erosion/deposition processes carving the meanders) and for tapering of widths (a proxy of landforming flowrates) appears to suggest the past existence on Mars of massive and relatively brief outbursts of flow. The range of duration of such processes might be speculated upon comparison with terrestrial processes.

  8. The Origin of River Meanders

    Science.gov (United States)

    Sahagian, D. L.; Chatanantavet, P.; Bradley, C.; Friedgen-Veitch, D.; Diplas, P.

    2015-12-01

    Various propositions for the origin of meanders have been suggested in the past, involving local disturbances such as variable bank material, obstructions to flow, and sediment transport. Each of these approaches has required a very special and complex set of circumstances for the onset of meandering. However, meanders have also been observed in other systems such as the gulf stream , window glass , glacial meltwater, channels in submarine fans, the jet stream, water faucets, and many others. What has not been satisfactorily demonstrated is why some rivers (or parts of rivers) should tend to meander in the first place rather than ply a straight course to base level. We suggest that the fundamental cause of the river meander instability is simply a minimization of power (rate of work done), with an onset that occurs when inertial terms exceed body forces (e.g. gravity) acting on the flow, and thus create an adverse pressure gradient directed in the opposite direction of the flow. A simple way to visualize the cause of the instability is that the water "backs up" upon itself, running into a parcel of water downstream that is flowing more slowly than the water upstream. This causes the direction of maximum local water surface slope to be diverted to one side or the other of the regional slope. This can occur when a river encounters the ocean (or a lake, or a break in slope), and can occur in many other situations as well. We analyzed various meandering systems globally, and conducted laboratory experiments under controlled conditions to determine the conditions necessary for the onset of the meander instability. The results indicate that the meander instability does not depend on sediment or erodible banks. The critical threshold for the onset of the meander instability occurs when inertial forces exceed body forces acting on the fluid such that an adverse pressure gradient arises. Better understanding of the meander instability should thus elucidate some of the

  9. Designing and Assessing Restored Meandering River Planform Using RVR Meander

    Science.gov (United States)

    Langendoen, E. J.; Abad, J. D.; Motta, D.; Frias, C. E.; Wong, M.; Barnes, B. J.; Anderson, C. D.; Garcia, M. H.; MacDonald, T. E.

    2013-12-01

    The ongoing modification and resulting reduction in water quality of U.S. rivers have led to a significant increase in river restoration projects over the last two decades. The increased interest in restoring degraded streams, however, has not necessarily led to improved stream function. Palmer and Allan (2005) found that many restoration projects fail to achieve their objectives due to the lack of policies to support restoration standards, to promote proven methods and to provide basic data needed for planning and implementation. Proven models of in-stream and riparian processes could be used not only to guide the design of restoration projects but also to assess both pre- and post-project indicators of ecological integrity. One of the most difficult types of river restoration projects concern reconstructing a new channel, often with an alignment and channel form different from those of the degraded pre-project channel. Recreating a meandering planform to provide longitudinal and lateral variability of flow and bed morphology to improve in-stream aquatic habitat is often desired. Channel meander planform is controlled by a multitude of variables, for example channel width to depth ratio, radius of curvature to channel width ratio, bankfull discharge, roughness, bed-material physical characteristics, bed material transport, resistance to erosion of the floodplain soils, riparian vegetation, etc. Therefore, current practices that use simple, empirically based relationships or reference reaches have led to failure in several instances, for example a washing out of meander bends or a highly unstable planform, because they fail to address the site-specific conditions. Recently, progress has been made to enhance a physically- and process-based model, RVR Meander, for rapid analysis of meandering river morphodynamics with reduced empiricism. For example, lateral migration is based on measurable physical properties of the floodplain soils and riparian vegetation versus

  10. Floodplain heterogeneity and meander migration

    Science.gov (United States)

    The impact of horizontal heterogeneity of floodplain soils on rates and patterns of meander migration is analyzed with a Ikeda et al. (1981)-type model for hydrodynamics and bed morphodynamics, coupled with a physically-based bank erosion model according to the approach developed by Motta et al. (20...

  11. Simulation of transients of high amplitude in pipe systems

    NARCIS (Netherlands)

    Boersma, J.M.; Looijmans, K.N.H.

    1999-01-01

    Fast high-amplitude transients ask for a non-linear modelling approach in which large density variations and heat exchange can be considered. Operation of safety-valves, relief valves, the occurrence of valve failure and the start-up or shutdown of rotating equipment in industrial pipe systems can l

  12. Subharmonic and fundamental high amplitude excitation of an axisymmetric jet

    Science.gov (United States)

    Raman, Ganesh; Rice, Edward J.

    1989-01-01

    The effect of simultaneous excitation at the fundamental and subharmonic frequencies on the behavior of a circular jet shear layer is studied. Attention is given to the effect of the initial phase difference, the Strouhal number pair, and amplitudes of the fundamental and subharmonic tones. High-amplitude excitation devices which can provide a wide range of forcing conditions when used in conjunction with equipment that produces complex waveforms are used.

  13. Valley evolution by meandering rivers

    Science.gov (United States)

    Limaye, Ajay Brian Sanjay

    Fluvial systems form landscapes and sedimentary deposits with a rich hierarchy of structures that extend from grain- to valley scale. Large-scale pattern formation in fluvial systems is commonly attributed to forcing by external factors, including climate change, tectonic uplift, and sea-level change. Yet over geologic timescales, rivers may also develop large-scale erosional and depositional patterns that do not bear on environmental history. This dissertation uses a combination of numerical modeling and topographic analysis to identify and quantify patterns in river valleys that form as a consequence of river meandering alone, under constant external forcing. Chapter 2 identifies a numerical artifact in existing, grid-based models that represent the co-evolution of river channel migration and bank strength over geologic timescales. A new, vector-based technique for bank-material tracking is shown to improve predictions for the evolution of meander belts, floodplains, sedimentary deposits formed by aggrading channels, and bedrock river valleys, particularly when spatial contrasts in bank strength are strong. Chapters 3 and 4 apply this numerical technique to establishing valley topography formed by a vertically incising, meandering river subject to constant external forcing---which should serve as the null hypothesis for valley evolution. In Chapter 3, this scenario is shown to explain a variety of common bedrock river valley types and smaller-scale features within them---including entrenched channels, long-wavelength, arcuate scars in valley walls, and bedrock-cored river terraces. Chapter 4 describes the age and geometric statistics of river terraces formed by meandering with constant external forcing, and compares them to terraces in natural river valleys. The frequency of intrinsic terrace formation by meandering is shown to reflect a characteristic relief-generation timescale, and terrace length is identified as a key criterion for distinguishing these

  14. Experimental meandering river with chute cutoffs

    NARCIS (Netherlands)

    Dijk, W.M. van; Lageweg, W.I. van de; Kleinhans, M.G.

    2012-01-01

    Braided rivers are relatively simple to produce in the laboratory, whereas dynamic meandering rivers have not been sustained beyond initial bend formation. Meandering is theoretically explained by bend instability growing from planimetric perturbation, which convects downstream. In this study, we ex

  15. High Amplitude (delta)-Scutis in the Large Magellanic Cloud

    Energy Technology Data Exchange (ETDEWEB)

    Garg, A; Cook, K H; Nikolaev, S; Huber, M E; Rest, A; Becker, A C; Challis, P; Clocchiatti, A; Miknaitis, G; Minniti, D; Morelli, L; Olsen, K; Prieto, J L; Suntzeff, N B; Welch, D L; Wood-Vasey, W M

    2010-01-25

    The authors present 2323 High-Amplitude {delta}-Scutis (HADS) candidates discovered in the Large Magellanic Cloud (LMC) by the SuperMACHO survey (Rest et al. 2005). Frequency analyses of these candidates reveal that several are multimode pulsators, including 119 whose largest amplitude of pulsation is in the fundamental (F) mode and 19 whose largest amplitude of pulsation is in the first overtone (FO) mode. Using Fourier decomposition of the HADS light curves, they find that the period-luminosity (PL) relation defined by the FO pulsators does not show a clear separation from the PL-relation defined by the F pulsators. This differs from other instability strip pulsators such as type c RR Lyrae. They also present evidence for a larger amplitude, subluminous population of HADS similar to that observed in Fornax (Poretti et al. 2008).

  16. High Amplitude \\delta-Scutis in the Large Magellanic Cloud

    CERN Document Server

    Garg, A; Nikolaev, S; Huber, M E; Rest, A; Becker, A C; Challis, P; Clocchiatti, A; Miknaitis, G; Minniti, D; Morelli, L; Olsen, K; Prieto, J L; Suntzeff, N B; Welch, D L; Wood-Vasey, W M

    2010-01-01

    We present 2323 High-Amplitude \\delta-Scuti (HADS) candidates discovered in the Large Magellanic Cloud (LMC) by the SuperMACHO survey (Rest et al. 2005). Frequency analyses of these candidates reveal that several are multimode pulsators, including 119 whose largest amplitude of pulsation is in the fundamental (F) mode and 19 whose largest amplitude of pulsation is in the first overtone (FO) mode. Using Fourier decomposition of the HADS light curves, we find that the period-luminosity (PL) relation defined by the FO pulsators does not show a clear separation from the PL-relation defined by the F pulsators. This differs from other instability strip pulsators such as type c RR Lyrae. We also present evidence for a larger amplitude, subluminous population of HADS similar to that observed in Fornax (Poretti et al. 2008).

  17. Injection coupling with high amplitude transverse modes: Experimentation and simulation

    Science.gov (United States)

    Mery, Yoann; Ducruix, Sébastien; Scouflaire, Philippe; Candel, Sébastien

    2009-06-01

    High frequency combustion instabilities have technical importance in the design of liquid rocket engines. These phenomena involve a strong coupling between transverse acoustic modes and combustion. They are currently being investigated by combining experimentation and numerical simulations. On the experimental level, the coupling is examined in a model scale system featuring a multiple injector combustor (MIC) comprising five coaxial injectors fed with liquid oxygen and gaseous methane. This system is equipped with a novel VHAM actuator (Very High Amplitude Modulator) which comprises two nozzles and a rotating toothed wheel blocking the nozzles in an alternate fashion. This device was designed to obtain the highest possible levels of transverse oscillation in the MIC. After a brief review of the VHAM, this article reports cold flow experiments using this modulator. Velocity maps obtained under resonant conditions using the VHAM are examined at different instants during a cycle of oscillation. Experimental data are compared with numerical pressure and velocity fields obtained from an acoustic solver. The good agreement observed in the nozzle vicinity indicates that numerical simulations can be used to analyze the complex flow field generated by the VHAM. To cite this article: Y. Mery et al., C. R. Mecanique 337 (2009).

  18. The High Amplitude delta Scuti Star AD Canis Minoris

    Science.gov (United States)

    Axelsen, R. A.; Napier-Munn, T.

    2016-12-01

    The high amplitude delta Scuti star AD Canis Minoris was studied by photoelectric photometry (PEP) during one night in in February 2011 and by digital single lens reflex (DSLR) photometry during seven nights in January and February 2016. Nine light curve peaks were captured, eight of them by DSLR photometry. A review of the literature enabled us to tabulate 109 times of maximum since 1959, to which we added 9 times of maximum from our data, thus creating the largest dataset to date for this star. Assuming a linear ephemeris, the period of AD CMi was calculated to be 0.122974511 (+/- 0.000000004) d, almost identical to that quoted in earlier literature. We constructed an observed minus computed (O-C) diagram which exhibited a quasi-sinusoidal shape, and fitted a weighted model characterised by combined quadratic and trigonometric functions. The fit indicates that the shape of the O-C diagram is attributable to the effects of a slow increase in the pulsation period of AD CMi at a constant rate, and the light time effect of a binary pair, confirming the results from previous authors, and updating most of the coefficients of the equation for the fitted model. The values of all of the coefficients in the function are statistically significant. The rate of increase in the pulsation period of AD CMi was calculated from the entire dataset to be dP/dt = 6.17 (+/- 0.75) x 10-9 d yr-1 or dP/Pdt = 5.01 (+/- 0.61) x 10-8 yr-1.

  19. River meander modeling and confronting uncertainty.

    Energy Technology Data Exchange (ETDEWEB)

    Posner, Ari J. (University of Arizona Tucson, AZ)

    2011-05-01

    This study examines the meandering phenomenon as it occurs in media throughout terrestrial, glacial, atmospheric, and aquatic environments. Analysis of the minimum energy principle, along with theories of Coriolis forces (and random walks to explain the meandering phenomenon) found that these theories apply at different temporal and spatial scales. Coriolis forces might induce topological changes resulting in meandering planforms. The minimum energy principle might explain how these forces combine to limit the sinuosity to depth and width ratios that are common throughout various media. The study then compares the first order analytical solutions for flow field by Ikeda, et al. (1981) and Johannesson and Parker (1989b). Ikeda's et al. linear bank erosion model was implemented to predict the rate of bank erosion in which the bank erosion coefficient is treated as a stochastic variable that varies with physical properties of the bank (e.g., cohesiveness, stratigraphy, or vegetation density). The developed model was used to predict the evolution of meandering planforms. Then, the modeling results were analyzed and compared to the observed data. Since the migration of a meandering channel consists of downstream translation, lateral expansion, and downstream or upstream rotations several measures are formulated in order to determine which of the resulting planforms is closest to the experimental measured one. Results from the deterministic model highly depend on the calibrated erosion coefficient. Since field measurements are always limited, the stochastic model yielded more realistic predictions of meandering planform evolutions. Due to the random nature of bank erosion coefficient, the meandering planform evolution is a stochastic process that can only be accurately predicted by a stochastic model.

  20. Monte Carlo Simulation of River Meander Modelling

    Science.gov (United States)

    Posner, A. J.; Duan, J. G.

    2010-12-01

    This study first compares the first order analytical solutions for flow field by Ikeda et. al. (1981) and Johanesson and Parker (1989b). Ikeda et. al.’s (1981) linear bank erosion model was implemented to predict the rate of bank erosion in which the bank erosion coefficient is treated as a stochastic variable that varies with physical properties of the bank (e.g. cohesiveness, stratigraphy, vegetation density). The developed model was used to predict the evolution of meandering planforms. Then, the modeling results were analyzed and compared to the observed data. Since the migration of meandering channel consists of downstream translation, lateral expansion, and downstream or upstream rotations. Several measures are formulated in order to determine which of the resulting planform is closest to the experimental measured one. Results from the deterministic model highly depend on the calibrated erosion coefficient. Since field measurements are always limited, the stochastic model yielded more realistic predictions of meandering planform evolutions. Due to the random nature of bank erosion coefficient, the meandering planform evolution is a stochastic process that can only be accurately predicted by a stochastic model. Quasi-2D Ikeda (1989) flow solution with Monte Carlo Simulation of Bank Erosion Coefficient.

  1. Origins and impacts of mesoscale meanders in the Agulhas Current

    Science.gov (United States)

    Elipot, S.; Beal, L. M.

    2014-12-01

    The Agulhas Current (AC) is the western boundary current of the South Indian subtropical gyre and is also the pathway for the inter-basin exchange of water, heat and salt between the Indian Ocean and the Atlantic Ocean, and thus a crucial part of the global overturning circulation of the world ocean. The AC, which otherwise flows stably along the coast of South Africa, undergoes dramatic offshore excursions from its mean path, forming large mesoscale solitary meanders propagating downstream and potentially linked to the leakage of Indian Ocean waters to the South Atlantic. These irregular meander events have been referred to as Natal Pulses.Here we present new observations and analyses of Agulhas meanders using full-depth velocity mooring observations from the Agulhas Current Time series experiment (ACT). Detailed analyses of the in-situ velocity reveal important differences between the behavior of the flow during solitary meander events and during meander events of smaller amplitude. During solitary meanders, an onshore cyclonic circulation and an offshore anticyclonic circulation act in concert to displace the jet offshore, leading to sudden and strong positive conversion of kinetic energy of the mean flow to the meander. In contrast, smaller amplitude meanderings are principally represented by a single cyclonic circulation spanning the entire jet that acts to displace the jet without significantly extracting kinetic energy from the mean flow. Solitary meander events can be traced upstream using satellite altimetry and linked to either Mozambique Channel eddies or Madagascar dipoles, the latter possibly part of a basin-wide pattern of propagating sea level anomalies consistent with Rossby wave dynamics. However, only a small number of these anomalies lead to solitary meanders. Altimetric observations suggest 1.5 meanders per year and show that the two-year period during ACT when no events were observed is unprecedented in the 20-year satellite record.

  2. River channel patterns: Braided, meandering, and straight

    Science.gov (United States)

    Leopold, Luna B.; Wolman, M. Gordon

    1957-01-01

    Channel pattern is used to describe the plan view of a reach of river as seen from an airplane, and includes meandering, braiding, or relatively straight channels. Natural channels characteristically exhibit alternating pools or deep reaches and riffles or shallow reaches, regardless of the type of pattern. The length of the pool or distance between riffles in a straight channel equals the straight line distance between successive points of inflection in the wave pattern of a meandering river of the same width. The points of inflection are also shallow points and correspond to riffles in the straight channel. This distance, which is half the wavelength of the meander, varies approximately as a linear function of channel width. In the data we analysed the meander wavelength, or twice the distance between successive riffles, is from 7 to 12 times the channel width. It is concluded that the mechanics which may lead to meandering operate in straight channels. River braiding is characterized by channel division around alluvial islands. The growth of an island begins as the deposition of a central bar which results from sorting and deposition of the coarser fractions of the load which locally cannot be transported. The bar grows downstream and in height by continued deposition on its surface, forcing the water into the flanking channels, which, to carry the flow, deepen and cut laterally into the original banks. Such deepening locally lowers the water surface and the central bar emerges as an island which becomes stabilized by vegetation. Braiding was observed in a small river in a laboratory. Measurements of the adjustments of velocity, depth, width, and slope associated with island development lead to the conclusion that braiding is one of the many patterns which can maintain quasi-equilibrium among discharge, load, and transporting ability. Braiding does not necessarily indicate an excess of total load. Channel cross section and pattern are ultimately controlled by

  3. Meanders of the Jialing River in China: Morphology and formation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    As a fundamental category of river system, comparisons in diverse regions and types with quantitative parameters on meander morphology will help to distinguish different characteristics and approach formations and evolutions. It also can provide scientific basis of geomorphology for their protections and exploitation of the meander resources. Based on the images of Google Earth, meanders' parameters are proposed and then measured and calculated. The result suggests that incised meanders in the Jialing River are among the most complex, irregular and sinuous channels. Special river gradient,geological structures, strata and lithology, backwater effect of landform are key factors to shape meanders of the Jialing River. The evolution of meander in the Jialing River obeys the principle of minimum-maximum energy dissipation. Easy acquisitions of remote sensing data make regional and global comparisons possible, and then the differences of formations can be explored. The morphology can probably provide an evidence of antecedent river and demonstrate the channel incisions and crustal uplifts. Meander core in Chinese is named after the isolated hills in the Jialing River. The incised meander is a kind of resource and needs to be protected.

  4. Meandering rivers - feedbacks between channel dynamics, floodplain and vegetation

    NARCIS (Netherlands)

    van Dijk, W.M.

    2013-01-01

    Rivers have distinctive channel patterns such as multi-channel braiding and single-channel meandering. Why these different river patterns emerge is only qualitatively understood. Yet, we have not been able to retain dynamic meandering in laboratory experiments. The main objective of this thesis was

  5. In search of objective manometric criteria for colonic high-amplitude propagated pressure waves

    NARCIS (Netherlands)

    De Schryver, AMP; Samsom, M; Smout, AJPM

    2002-01-01

    The aims of this study were to explore all characteristics of high-amplitude propagated contractions (HAPCs) that would allow them to be distinguished from nonHAPC colonic pressure waves, and to develop computer algorithms for automated HAPC detection. Colonic manometry recordings obtained from 24 h

  6. Brh V128 is a Double-Mode High-Amplitude delta Scuti Star

    Science.gov (United States)

    Bernhard, K.; Pejcha, O.; Proksch, W.; Quester, W.; van Cauteren, P.; Wils, P.

    2004-08-01

    CCD-V and unfiltered photometric data show that Brh V128 = GSC 1893-89 is a new high-amplitude double-mode Delta Scuti variable with a fundamental period of 0.1534 days and a period ratio of 0.767. The amplitude of the first overtone pulsation is slightly larger than that of the fundamental mode.

  7. Fabrication of Meander and Spiral Type Micro Inductors

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    To obtain microstructure of magnetic devices, the thin film inductors were fabricated by the process such as thin film manufacturing, photolithography and wet etching. The freouency characteristics of these devices are measured at high frequency range. When the inductor sizes of the spiral and the meander type are same, the inductance and the quality factor of the spiral type inductor are larger than those of the meander type inductor, but the driving frequency of the spiral type inductor is lower than that of the meander type inductor.

  8. Non-Linear High Amplitude Oscillations in Wave-shaped Resonators

    Science.gov (United States)

    Antao, Dion; Farouk, Bakhtier

    2011-11-01

    A numerical and experimental study of non-linear, high amplitude standing waves in ``wave-shaped'' resonators is reported here. These waves are shock-less and can generate peak acoustic overpressures that can exceed the ambient pressure by three/four times its nominal value. A high fidelity compressible axisymmetric computational fluid dynamic model is used to simulate the phenomena in cylindrical and arbitrarily shaped axisymmetric resonators. Working fluids (Helium, Nitrogen and R-134a) at various operating pressures are studied. The experiments are performed in a constant cross-section cylindrical resonator in atmospheric pressure nitrogen and helium to provide model validation. The high amplitude non-linear oscillations demonstrated can be used as a prime mover in a variety of applications including thermoacoustic cryocooling. The work reported is supported by the US National Science Foundation under grant CBET-0853959.

  9. Analysis of the Petersen Diagram of Double-Mode High-Amplitude {\\delta} Scuti Stars

    CERN Document Server

    Furgoni, Riccardo

    2016-01-01

    I created the Petersen diagram relative to all the Double Mode High Amplitude {\\delta} Scuti stars listed in the AAVSO's International Variable Star Index up to date December 29, 2015. For the first time I noticed that the ratio between the two periods P1/P0 seems in evident linear relation with the duration of the period P0, a finding never explicitly described in literature regarding this topic.

  10. VizieR Online Data Catalog: VVV high amplitude NIR variable stars (Contreras Pena+, 2017)

    Science.gov (United States)

    Contreras Pena, C.; Lucas, P. W.; Minniti, D.; Kurtev, R.; Stimson, W.; Navarro Molina, C.; Borissova, J.; Kumar, M. S. N.; Thompson, M. A.; Gledhill, T.; Terzi, R.; Froebrich, D.; Caratti o Garatti, A.

    2017-08-01

    We present the single epoch ZYJHKs photometry obtained from VVV catalogues for 816 high-amplitude variables. We also present the amplitude of the Ks light curve of the objects derived from 2010-2015 photometry. For each object we also provide a provisional classification derived from the shape of the light curve. For objects found to be likely associated with SFRs we present an spectral index derived from the object's spectral energy distribution. (2 data files).

  11. Kepler observations of the high-amplitude δ Scuti star V2367 Cyg

    DEFF Research Database (Denmark)

    Balona, L. A.; Lenz, P.; Antoci, V.

    2012-01-01

    We analyse Kepler observations of the high-amplitude δ Scuti (HADS) star V2367 Cyg (KIC 9408694). The variations are dominated by a mode with frequency f1= 5.6611 d−1. Two other independent modes with f2= 7.1490 d−1 and f3= 7.7756 d−1 have amplitudes an order of magnitude smaller than f1. Nearly ...

  12. Meander applications at landslides in alluvium valleys

    Science.gov (United States)

    Yilmaz, L.

    2012-04-01

    For calculation of bed variation in alluvial channels important bed configurations include meso-scale bed configurations, such as alternating bars (pools and riffles) and braided bars. It is important in river management to be able to predict water surface elevation, scour, and fill in alluvial channels under given flow conditions. Mathematical and physical models can be used in designing or planning for improvement of river channels and hydraulic structures. Several studies have been made to evaluate flow and bed variation in meandering channels (Engelund, 1974; Odgaard, 1986; Ikeda et al., 1987; Falcon and Kennedy, 1983; Kishi et al., 1983, Struiksma, 1985, and Struiksma et al., 1985). The bed variation at meandering channels is calculated by the continuity equation for bed load transport. Typical bed configurations and flows with alternating bars and braided bars are produced in straight channels, and thus the formation and migration of bars are predicted quantitatively. The results of model applications were carried out for the same situations as the mathematical model at the Technical University of Berlin, Institute Wasserbau and Wasserwirtschaft (Yilmaz, 1990), started with flat bed, continued until dz/ dt=0. Then the beds were solidified, and precise measurements of the bed configuration and the velocity were performed. Plan geometries of runs consist of a sine-generated curve and an asymmetrical meander loop, respectively. The latter is derived by a Fourier series analysis on several typical bends. The meso-scale bed configuration in alluvial streams is highly dependent on the width-depth ratio of the channel. The velocity measurements were made with small mechanical current meters fixed to a 1m high frame that rested on the bottom while measuring the lower points on the profile. The frame was suspended at different levels above the bottom to collect the data represented by the higher points. Velocity profiles are plotted semi-logarithmically with the dots

  13. Martian Meanders: Wavelength-Width Scaling and Flow Duration

    Science.gov (United States)

    Gregoire-Mazzocco, H.; Stepinski, T. F.; McGovern, P. J.; Lanzoni, S.; Frascati, A.; Rinaldo, A.

    2006-03-01

    Martian meanders reveals linear wavelength/width scaling with a coef. k~10, that can be used to estimate discharges. Simulations of channel evolution are used to determine flow duration from sinuosity. Application to Nirgal Vallis yields 200 yrs.

  14. Stream-power model of meander cutoff in gravel beds

    Science.gov (United States)

    Pannone, M.; De Vincenzo, A.

    2016-12-01

    In the present study we propose a one-dimensional model for the prediction of the large-time evolution of river meanders (pre-cutoff conditions) characterized by gravel bed and negligible suspended load. Due to its relatively simple structure, it may be a fast and easy tool to forecast the time evolution of a bend when the symptoms of an incipient instability suggest quantifying the time left for river exploitation as a naturalistic or a commercial resource and timely planning, if needed, the site management and restoration. Most of the previous research on meandering rivers focused on linearized theories that apply to very small bend amplitudes and very large radii of curvature. The dynamics of meander growth and cutoff was typically afforded by case-sensitive numerical simulations or by descriptive methods aimed at deriving purely empirical laws relating the hydraulics to some geomorphological parameters. The present approach combines the immediacy of a general analytical model with the accuracy of a fluid-mechanical background. The model focuses on energetic principles and interprets the mechanism of meander cutoff as the achievement of limit conditions in terms of river stream power. The corresponding analytical solution, which consists in a 1-D deterministic integro-differential equation governing the meander pre-cutoff phase, accounts for the influence of the morphological and sedimentological parameters by the downstream migration rate and the radius of the meander osculating circle. The results, expressed in terms of instable meander lifetime, are in good agreement with the data obtained from a number of field surveys documented in literature. Additionally, the proposed fluid-mechanical model allows identifying the physical mechanisms responsible for some peculiarities of large-time meander evolution like the decreasing skewness and asymmetry.

  15. Simulation Comparisons of Three Different Meander Line Dipoles

    Science.gov (United States)

    2015-01-01

    number of meanders and a different definition can result in a different answer. 31 = � 12.0674(−2) log�2−2 �− 0.7245 � (1...with a tapered micro-strip line feed; the structure and modifications were validated in a previous report.7 Due to the space restrictions, the arms...maintain relative consistency with the definition of a meander. 3. Simulations The simulations were done using computer-aided design (CAD) FEKO3

  16. Cycloidal meandering of a mesoscale anticyclonic eddy

    Science.gov (United States)

    Kizner, Ziv; Shteinbuch-Fridman, Biana; Makarov, Viacheslav; Rabinovich, Michael

    2017-08-01

    By applying a theoretical approach, we propose a hypothetical scenario that might explain some features of the movement of a long-lived mesoscale anticyclone observed during 1990 in the Bay of Biscay [R. D. Pingree and B. Le Cann, "Three anticyclonic slope water oceanic eddies (SWODDIES) in the southern Bay of Biscay in 1990," Deep-Sea Res., Part A 39, 1147 (1992)]. In the remote-sensing infrared images, at the initial stage of observations, the anticyclone was accompanied by two cyclonic eddies, so the entire structure appeared as a tripole. However, at later stages, only the anticyclone was seen in the images, traveling generally west. Unusual for an individual eddy were the high speed of its motion (relative to the expected planetary beta-drift) and the presence of almost cycloidal meanders in its trajectory. Although surface satellites seem to have quickly disappeared, we hypothesize that subsurface satellites continued to exist, and the coherence of the three vortices persisted for a long time. A significant perturbation of the central symmetry in the mutual arrangement of three eddies constituting a tripole can make reasonably fast cycloidal drift possible. This hypothesis is tested with two-layer contour-dynamics f-plane simulations and with finite-difference beta-plane simulations. In the latter case, the interplay of the planetary beta-effect and that due to the sloping bottom is considered.

  17. Rapid high-amplitude circumferential slow wave propagation during normal gastric pacemaking and dysrhythmias.

    Science.gov (United States)

    O'Grady, G; Du, P; Paskaranandavadivel, N; Angeli, T R; Lammers, W J E P; Asirvatham, S J; Windsor, J A; Farrugia, G; Pullan, A J; Cheng, L K

    2012-07-01

    Gastric slow waves propagate aborally as rings of excitation. Circumferential propagation does not normally occur, except at the pacemaker region. We hypothesized that (i) the unexplained high-velocity, high-amplitude activity associated with the pacemaker region is a consequence of circumferential propagation; (ii) rapid, high-amplitude circumferential propagation emerges during gastric dysrhythmias; (iii) the driving network conductance might switch between interstitial cells of Cajal myenteric plexus (ICC-MP) and circular interstitial cells of Cajal intramuscular (ICC-IM) during circumferential propagation; and (iv) extracellular amplitudes and velocities are correlated. An experimental-theoretical study was performed. High-resolution gastric mapping was performed in pigs during normal activation, pacing, and dysrhythmia. Activation profiles, velocities, and amplitudes were quantified. ICC pathways were theoretically evaluated in a bidomain model. Extracellular potentials were modeled as a function of membrane potentials. High-velocity, high-amplitude activation was only recorded in the pacemaker region when circumferential conduction occurred. Circumferential propagation accompanied dysrhythmia in 8/8 experiments was faster than longitudinal propagation (8.9 vs 6.9 mm s(-1) ; P = 0.004) and of higher amplitude (739 vs 528 μV; P = 0.007). Simulations predicted that ICC-MP could be the driving network during longitudinal propagation, whereas during ectopic pacemaking, ICC-IM could outpace and activate ICC-MP in the circumferential axis. Experimental and modeling data demonstrated a linear relationship between velocities and amplitudes (P propagation. Rapid circumferential propagation also emerges during a range of gastric dysrhythmias, elevating extracellular amplitudes and organizing transverse wavefronts. One possible explanation for these findings is bidirectional coupling between ICC-MP and circular ICC-IM networks. © 2012 Blackwell Publishing Ltd.

  18. High amplitude nonlinear acoustic wave driven flow fields in cylindrical and conical resonators.

    Science.gov (United States)

    Antao, Dion Savio; Farouk, Bakhtier

    2013-08-01

    A high fidelity computational fluid dynamic model is used to simulate the flow, pressure, and density fields generated in a cylindrical and a conical resonator by a vibrating end wall/piston producing high-amplitude standing waves. The waves in the conical resonator are found to be shock-less and can generate peak acoustic overpressures that exceed the initial undisturbed pressure by two to three times. A cylindrical (consonant) acoustic resonator has limitations to the output response observed at one end when the opposite end is acoustically excited. In the conical geometry (dissonant acoustic resonator) the linear acoustic input is converted to high energy un-shocked nonlinear acoustic output. The model is validated using past numerical results of standing waves in cylindrical resonators. The nonlinear nature of the harmonic response in the conical resonator system is further investigated for two different working fluids (carbon dioxide and argon) operating at various values of piston amplitude. The high amplitude nonlinear oscillations observed in the conical resonator can potentially enhance the performance of pulse tube thermoacoustic refrigerators and these conical resonators can be used as efficient mixers.

  19. Modelling of meander migration in an incised channel

    Institute of Scientific and Technical Information of China (English)

    Jianchun HUANG; Blair P GREIMANN; Timothy J RANDLE

    2014-01-01

    An updated linear computer model for meandering rivers with incision has been developed. The model simulates the bed topography, flow field, and bank erosion rate in an incised meandering channel. In a scenario where the upstream sediment load decreases (e.g., after dam closure or soil conservation), alluvial river experiences cross section deepening and slope flattening. The channel migration rate might be affected in two ways:decreased channel slope and steeped bank height. The proposed numerical model combines the traditional one-dimensional (1D) sediment transport model in simulating the channel erosion and the linear model for channel meandering. A non-equilibrium sediment transport model is used to update the channel bed elevation and gradations. A linear meandering model was used to calculate the channel alignment and bank erosion/accretion, which in turn was used by the 1D sediment transport model. In the 1D sediment transport model, the channel bed elevation and gradations are represented in each channel cross section. In the meandering model, the bed elevation and gradations are stored in two dimensional (2D) cells to represent the channel and terrain properties (elevation and gradation). A new method is proposed to exchange information regarding bed elevations and bed material fractions between 1D river geometry and 2D channel and terrain. The ability of the model is demonstrated using the simulation of the laboratory channel migration of Friedkin in which channel incision occurs at the upstream end.

  20. Don't Fence Me In: Free Meanders in a Confined River Valley

    Science.gov (United States)

    Eke, E. C.; Wilcock, P. R.

    2015-12-01

    The interaction between meandering river channels and inerodible valley walls provides a useful test of our ability to understand meander dynamics. In some cases, river meanders confined between valley walls display distinctive angular bends in a dynamic equilibrium such that their size and shape persist as the meander migrates. In other cases, meander geometry is more varied and changes as the meander migrates. The ratio of channel to valley width has been identified as a useful parameter for defining confined meanders, but is not sufficient to distinguish cases in which sharp angular bends are able to migrate with little change in geometry. Here, we examine the effect of water and sediment supply on the geometry of confined rivers in order to identify conditions under which meander geometry reaches a persistent dynamic equilibrium. Because channel width and meander geometry are closely related, we use a numerical meander model that allows for independent migration of both banks, thereby allowing channel width to vary in space and time. We hypothesize that confined meanders with persistent angular bends have smaller transport rates of bed material and that their migration is driven by erosion of the cutbank (bank-pull migration). When bed material supply is sufficiently large that point bar deposition drives meander migration (bar-push migration), confined meander bends have a larger radius of curvature and a geometry that varies as the meander migrates. We test this hypothesis using historical patterns of confined meander migration for rivers with different rates of sediment supply and bed material transport. Interpretation of the meander migration pattern is provided by the free-width meander migration model.

  1. Experimental investigation of Mars meandering rivers: Chemical precipitation process

    Science.gov (United States)

    Kim, W.; Lim, Y.; Cleveland, J.; Reid, E.; Jew, C.

    2014-12-01

    On Earth, meandering streams occur where the banks are resistant to erosion, which enhances narrow and deep channels. Often this is because the stream banks are held firm by vegetation. The ancient, highly sinuous channels with cutoffs found on Mars are enigmatic because vegetation played no role in providing bank cohesion and enhancing fine sediment deposition. Possible causes of the meandering therefore include ice under permafrost conditions and chemical processes. We conducted carbonate flume experiments to investigate possible mechanisms creating meandering channels other than vegetation. The experiment includes a tank that dissolves limestone by adding CO2 gas and produces artificial spring water, peristaltic pumps to drive water through the system, a heater to control the temperature of the spring water, and a flume where carbonate sediment deposits. Spring water containing dissolved calcium and carbonate ions moves through a heater to increase temperature, and then into the flume. The flume surface is open to the air to allow CO2 degassing, decrease temperature, and increase pH, which promotes carbonate precipitation. A preliminary experiment was done and successfully created a meander pattern that evolved over a 3-day experiment. The experiment showed lateral migration of the bend and avulsion of the stream, similar to a natural meander. The lateral variation in flow speed increased the local residence time of water, thus increasing the degassing of CO2 on the two sides of the flow and promoting more precipitation. This enhanced precipitation on the sides provided a mechanism to build levees along the channel and created a stream confined in a narrow path. This mechanism also potentially applies to Earthly single thread and/or meandering rivers developed and recorded before vegetation appeared on Earth's surface.

  2. Pulsation analysis of the high amplitude δ Scuti star CW Serpentis

    Science.gov (United States)

    Niu, Jia-Shu; Fu, Jian-Ning; Zong, Wei-Kai

    2013-10-01

    Time-series photometric observations were made for the high amplitude δ Scuti star CW Ser between 2011 and 2012 at the Xinglong Station of National Astronomical Observatories, Chinese Academy of Sciences. After performing the frequency analysis of the light curves, we confirmed the fundamental frequency of f = 5.28677 c d-1, together with seven harmonics of the fundamental frequency, which are newly detected. No additional frequencies were detected. The O — C diagram, produced with the 21 newly determined times of maximum light combined with those provided in the literature, helps to obtain a new ephemeris formula of the times of maximum light with the pulsation period of 0.189150355 ± 0.000000003 d.

  3. The analysis of high amplitude of potential oscillations near the hollow cathode of ion thruster

    Science.gov (United States)

    Qin, Yu; Xie, Kan; Guo, Ning; Zhang, Zun; Zhang, Cen; Gu, Zengjie; Zhang, Yu; Jiang, Zhaorui; Ouyang, Jiting

    2017-05-01

    The influence of gas flow, current level, and different shapes of anode on the oscillation amplitude and the characteristics of the hollow cathode discharge were investigated. The average plasma potential, temporal measurements of plasma potential, ion density, the electron temperature, as well as waveforms of plasma potential for test conditions were measured. At the same time, the time-resolved images of the plasma plume were also recorded. The results show that the potential oscillations appear at high discharge current or low flow rate. The potential oscillation boundaries, the position of maximum amplitude of plasma potential, and the position where the highest ion density was observed, were found. Both of the positions are affected by different shapes of anode configurations. This high amplitude of potential oscillations is ionization-like instabilities. The xenon ions ionized in space was analyzed for the fast potential rise and spatial dissipation of the space xenon ions was the reason for the gradual potential delay.

  4. WEATHER ON OTHER WORLDS. III. A SURVEY FOR T DWARFS WITH HIGH-AMPLITUDE OPTICAL VARIABILITY

    Energy Technology Data Exchange (ETDEWEB)

    Heinze, Aren N.; Metchev, Stanimir [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States); Kellogg, Kendra, E-mail: aren.heinze@stonybrook.edu, E-mail: smetchev@uwo.ca [Department of Physics and Astronomy, The University of Western Ontario, 1151 Richmond St, London, ON N6A 3K7 (Canada)

    2015-03-10

    We have monitored 12 T dwarfs with the Kitt Peak 2.1 m telescope using an F814W filter (0.7-0.95 μm) to place in context the remarkable 10%-20% variability exhibited by the nearby T dwarf Luhman 16B in this wavelength regime. The motivation was the poorly known red optical behavior of T dwarfs, which have been monitored almost exclusively at infrared wavelengths, where variability amplitudes greater than 10% have been found to be very rare. We detect highly significant variability in two T dwarfs. The T2.5 dwarf 2MASS 13243559+6358284 shows consistent ∼17% variability on two consecutive nights. The T2 dwarf 2MASS J16291840+0335371 exhibits ∼10% variability that may evolve from night to night, similarly to Luhman 16B. Both objects were previously known to be variable in the infrared, but with considerably lower amplitudes. We also find evidence for variability in the T6 dwarf J162414.37+002915.6, but since it has lower significance, we conservatively refrain from claiming this object as a variable. We explore and rule out various telluric effects, demonstrating that the variations we detect are astrophysically real. We suggest that high-amplitude photometric variability for T dwarfs is likely more common in the red optical than at longer wavelengths. The two new members of the growing class of high-amplitude variable T dwarfs offer excellent prospects for further study of cloud structures and their evolution.

  5. Optimization of meander line antennas for RFID applications by using genetic algorithm

    Science.gov (United States)

    Bucuci, Stefania C.; Anchidin, Liliana; Dumitrascu, Ana; Danisor, Alin; Berescu, Serban; Tamas, Razvan D.

    2015-02-01

    In this paper, we propose an approach of optimization of meander line antennas by using genetic algorithm. Such antennas are used in RFID applications. As opposed to other approaches for meander antennas, we propose the use of only two optimization objectives, i.e. gain and size. As an example, we have optimized a single meander dipole antenna, resonating at 869 MHz.

  6. Changes in meandering of the Northern Hemisphere circulation

    Science.gov (United States)

    Di Capua, Giorgia; Coumou, Dim

    2016-09-01

    Strong waves in the mid-latitude circulation have been linked to extreme surface weather and thus changes in waviness could have serious consequences for society. Several theories have been proposed which could alter waviness, including tropical sea surface temperature anomalies or rapid climate change in the Arctic. However, so far it remains unclear whether any changes in waviness have actually occurred. Here we propose a novel meandering index which captures the maximum waviness in geopotential height contours at any given day, using all information of the full spatial position of each contour. Data are analysed on different time scale (from daily to 11 day running means) and both on hemispheric and regional scales. Using quantile regressions, we analyse how seasonal distributions of this index have changed over 1979-2015. The most robust changes are detected for autumn which has seen a pronounced increase in strongly meandering patterns at the hemispheric level as well as over the Eurasian sector. In summer for both the hemisphere and the Eurasian sector, significant downward trends in meandering are detected on daily timescales which is consistent with the recently reported decrease in summer storm track activity. The American sector shows the strongest increase in meandering in the warm season: in particular for 11 day running mean data, indicating enhanced amplitudes of quasi-stationary waves. Our findings have implications for both the occurrence of recent cold spells and persistent heat waves in the mid-latitudes.

  7. On the steadiness of separating and meandering currents

    NARCIS (Netherlands)

    van Leeuwen, P.J.; de Ruijter, W.P.M.

    2009-01-01

    The existence of inertial steady currents that separate from a coast and meander afterward is investigated. By integrating the zonal momentum equation over a suitable area, it is shown that retroflecting currents cannot be steady in a reduced gravity or in a barotropic model of the ocean. Even frict

  8. Simulating river meandering processes using stochastic bank erosion coefficient

    Science.gov (United States)

    Posner, Ari J.; Duan, Jennifer G.

    2012-08-01

    This study first compares the first order analytical solutions for flow field by Ikeda et. al. (1981) and Johanesson and Parker (1989b). Ikeda et. al.'s (1981) linear model of bank erosion was implemented to predict the rate of bank erosion in which the bank erosion coefficient is treated as a stochastic variable that varies with physical properties of the bank (e.g. cohesiveness, stratigraphy, vegetation density). The developed model was used to predict the evolution of meandering planforms. Then, the modeling results were analyzed and compared to the observed data. Because the migration of meandering channels consists of downstream translation, lateral expansion, and downstream or upstream rotations, several measures are formulated to determine which of the resulting planform is closest to the experimental measured one. Results from the deterministic model highly depend on the calibrated erosion coefficient. Because field measurements are always limited, the stochastic model yielded more realistic predictions of meandering planform evolutions. Because the coefficient of bank erosion is a random variable, the meandering planform evolution is a stochastic process that can only be accurately predicted by a stochastic model.

  9. Modeling meander morphodynamics over self-formed heterogeneous floodplains

    Science.gov (United States)

    Bogoni, Manuel; Putti, Mario; Lanzoni, Stefano

    2017-06-01

    This work addresses the signatures embedded in the planform geometry of meandering rivers consequent to the formation of floodplain heterogeneities as the river bends migrate. Two geomorphic features are specifically considered: scroll bars produced by lateral accretion of point bars at convex banks and oxbow lake fills consequent to neck cutoffs. The sedimentary architecture of these geomorphic units depends on the type and amount of sediment, and controls bank erodibility as the river impinges on them, favoring or contrasting the river migration. The geometry of numerically generated planforms obtained for different scenarios of floodplain heterogeneity is compared to that of natural meandering paths. Half meander metrics and spatial distribution of channel curvatures are used to disclose the complexity embedded in meandering geometry. Fourier Analysis, Principal Component Analysis, Singular Spectrum Analysis and Multivariate Singular Spectrum Analysis are used to emphasize the subtle but crucial differences which may emerge between apparently similar configurations. A closer similarity between observed and simulated planforms is attained when fully coupling flow and sediment dynamics (fully-coupled models) and when considering self-formed heterogeneities that are less erodible than the surrounding floodplain.

  10. Preservation of meandering river channels in uniformly aggrading channel belts

    NARCIS (Netherlands)

    van de Lageweg, W.I.; Schuurman, F.; Cohen, K.M.; van Dijk, W. M.; Shimizu, Y.; Kleinhans, M.G.

    2016-01-01

    Channel belt deposits from meandering river systems commonly display an internal architecture of stacked depositional features with scoured basal contacts due to channel and bedform migration across a range of scales. Recognition and correct interpretation of these bounding surfaces is essential to

  11. Low-frequency meandering piezoelectric vibration energy harvester.

    Science.gov (United States)

    Berdy, David F; Srisungsitthisunti, Pornsak; Jung, Byunghoo; Xu, Xianfan; Rhoads, Jeffrey F; Peroulis, Dimitrios

    2012-05-01

    The design, fabrication, and characterization of a novel low-frequency meandering piezoelectric vibration energy harvester is presented. The energy harvester is designed for sensor node applications where the node targets a width-to-length aspect ratio close to 1:1 while simultaneously achieving a low resonant frequency. The measured power output and normalized power density are 118 μW and 5.02 μW/mm(3)/g(2), respectively, when excited by an acceleration magnitude of 0.2 g at 49.7 Hz. The energy harvester consists of a laser-machined meandering PZT bimorph. Two methods, strain-matched electrode (SME) and strain-matched polarization (SMP), are utilized to mitigate the voltage cancellation caused by having both positive and negative strains in the piezoelectric layer during operation at the meander's first resonant frequency. We have performed finite element analysis and experimentally demonstrated a prototype harvester with a footprint of 27 x 23 mm and a height of 6.5 mm including the tip mass. The device achieves a low resonant frequency while maintaining a form factor suitable for sensor node applications. The meandering design enables energy harvesters to harvest energy from vibration sources with frequencies less than 100 Hz within a compact footprint.

  12. Facilitation of epileptic activity during sleep is mediated by high amplitude slow waves.

    Science.gov (United States)

    Frauscher, Birgit; von Ellenrieder, Nicolás; Ferrari-Marinho, Taissa; Avoli, Massimo; Dubeau, François; Gotman, Jean

    2015-06-01

    Epileptic discharges in focal epilepsy are frequently activated during non-rapid eye movement sleep. Sleep slow waves are present during this stage and have been shown to include a deactivated ('down', hyperpolarized) and an activated state ('up', depolarized). The 'up' state enhances physiological rhythms, and we hypothesize that sleep slow waves and particularly the 'up' state are the specific components of non-rapid eye movement sleep that mediate the activation of epileptic activity. We investigated eight patients with pharmaco-resistant focal epilepsies who underwent combined scalp-intracerebral electroencephalography for diagnostic evaluation. We analysed 259 frontal electroencephalographic channels, and manually marked 442 epileptic spikes and 8487 high frequency oscillations during high amplitude widespread slow waves, and during matched control segments with low amplitude widespread slow waves, non-widespread slow waves or no slow waves selected during the same sleep stages (total duration of slow wave and control segments: 49 min each). During the slow waves, spikes and high frequency oscillations were more frequent than during control segments (79% of spikes during slow waves and 65% of high frequency oscillations, both P ∼ 0). The spike and high frequency oscillation density also increased for higher amplitude slow waves. We compared the density of spikes and high frequency oscillations between the 'up' and 'down' states. Spike and high frequency oscillation density was highest during the transition from the 'up' to the 'down' state. Interestingly, high frequency oscillations in channels with normal activity expressed a different peak at the transition from the 'down' to the 'up' state. These results show that the apparent activation of epileptic discharges by non-rapid eye movement sleep is not a state-dependent phenomenon but is predominantly associated with specific events, the high amplitude widespread slow waves that are frequent, but not

  13. Turbulent large-scale structure effects on wake meandering

    Science.gov (United States)

    Muller, Y.-A.; Masson, C.; Aubrun, S.

    2015-06-01

    This work studies effects of large-scale turbulent structures on wake meandering using Large Eddy Simulations (LES) over an actuator disk. Other potential source of wake meandering such as the instablility mechanisms associated with tip vortices are not treated in this study. A crucial element of the efficient, pragmatic and successful simulations of large-scale turbulent structures in Atmospheric Boundary Layer (ABL) is the generation of the stochastic turbulent atmospheric flow. This is an essential capability since one source of wake meandering is these large - larger than the turbine diameter - turbulent structures. The unsteady wind turbine wake in ABL is simulated using a combination of LES and actuator disk approaches. In order to dedicate the large majority of the available computing power in the wake, the ABL ground region of the flow is not part of the computational domain. Instead, mixed Dirichlet/Neumann boundary conditions are applied at all the computational surfaces except at the outlet. Prescribed values for Dirichlet contribution of these boundary conditions are provided by a stochastic turbulent wind generator. This allows to simulate large-scale turbulent structures - larger than the computational domain - leading to an efficient simulation technique of wake meandering. Since the stochastic wind generator includes shear, the turbulence production is included in the analysis without the necessity of resolving the flow near the ground. The classical Smagorinsky sub-grid model is used. The resulting numerical methodology has been implemented in OpenFOAM. Comparisons with experimental measurements in porous-disk wakes have been undertaken, and the agreements are good. While temporal resolution in experimental measurements is high, the spatial resolution is often too low. LES numerical results provide a more complete spatial description of the flow. They tend to demonstrate that inflow low frequency content - or large- scale turbulent structures - is

  14. High amplitude theta wave bursts: a novel electroencephalographic feature of rem sleep and cataplexy.

    Science.gov (United States)

    Lo Martire, Viviana Carmen; Bastianini, Stefano; Berteotti, Chiara; Silvani, Alessandro; Zoccoli, Giovanna

    2015-01-01

    High amplitude theta wave bursts (HATs) were originally described during REMS and cataplexy in ORX-deficient mice as a novel neurophysiological correlate of narcolepsy (Bastianini et al., 2012). This finding was replicated the following year by Vassalli et al. in both ORX-deficient narcoleptic mice and narcoleptic children during cataplexy episodes (Vassalli et al., 2013). The relationship between HATs and narcolepsy-cataplexy in mice and patients indicates that the lack of ORX peptides is responsible for this abnormal EEG activity, the physiological meaning of which is still unknown. This review aimed to explore different phasic EEG events previously described in the published literature in order to find analogies and differences with HATs observed in narcoleptic mice and patients. We found similarities in terms of morphology, frequency and duration between HATs and several physiological (mu and wicket rhythms, sleep spindles, saw-tooth waves) or pathological (SWDs, HVSs, bursts of polyphasic complexes EEG complexes reported in a mouse model of CJD, and BSEs) EEG events. However, each of these events also shows significant differences from HATs, and thus cannot be equaled to them. The available evidence thus suggests that HATs are a novel neurophysiological phenomenon. Further investigations on HATs are required in order to investigate their physiological meaning, to individuate their brain structure(s) of origin, and to clarify the neural circuits involved in their manifestation.

  15. Nonlinear reflection of high-amplitude laser pulses from relativistic electron mirrors

    Science.gov (United States)

    Kulagin, V. V.; Kornienko, V. N.; Cherepenin, V. A.

    2016-04-01

    A coherent X-ray pulse of attosecond duration can be formed in the reflection of a counterpropagating laser pulse from a relativistic electron mirror. The reflection of a high-amplitude laser pulse from the relativistic electron mirror located in the field of an accelerating laser pulse is investigated by means of two-dimensional (2D) numerical simulation. It is shown that provided the amplitude of the counterpropagating laser pulse is several times greater than the amplitude of the accelerating laser pulse, the reflection process is highly nonlinear, which causes a significant change in the X-ray pulse shape and its shortening up to generation of quasi-unipolar pulses and single-cycle pulses. A physical mechanism responsible for this nonlinearity of the reflection process is explained, and the parameters of the reflected X-ray pulses are determined. It is shown that the duration of these pulses may constitute 50 - 60 as, while their amplitude may be sub-relativistic.

  16. High amplitude phase resetting in rev-erbalpha/per1 double mutant mice.

    Directory of Open Access Journals (Sweden)

    Corinne Jud

    Full Text Available Over time, organisms developed various strategies to adapt to their environment. Circadian clocks are thought to have evolved to adjust to the predictable rhythms of the light-dark cycle caused by the rotation of the Earth around its own axis. The rhythms these clocks generate persist even in the absence of environmental cues with a period of about 24 hours. To tick in time, they continuously synchronize themselves to the prevailing photoperiod by appropriate phase shifts. In this study, we disrupted two molecular components of the mammalian circadian oscillator, Rev-Erbalpha and Period1 (Per1. We found that mice lacking these genes displayed robust circadian rhythms with significantly shorter periods under constant darkness conditions. Strikingly, they showed high amplitude resetting in response to a brief light pulse at the end of their subjective night phase, which is rare in mammals. Surprisingly, Cry1, a clock component not inducible by light in mammals, became slightly inducible in these mice. Taken together, Rev-Erbalpha and Per1 may be part of a mechanism preventing drastic phase shifts in mammals.

  17. Adhesive bond strength evaluation in composite materials by laser-generated high amplitude ultrasound

    Science.gov (United States)

    Perton, M.; Blouin, A.; Monchalin, J.-P.

    2011-01-01

    Adhesive bonding of composites laminates is highly efficient but is not used for joining primary aircraft structures, since there is presently no nondestructive inspection technique to ensure the quality of the bond. We are developing a technique based on the propagation of high amplitude ultrasonic waves to evaluate the adhesive bond strength. Large amplitude compression waves are generated by a short pulse powerful laser under water confinement and are converted after reflection by the assembly back surface into tensile waves. The resulting tensile stresses can cause a delamination inside the laminates or at the bond interfaces. The adhesion strength is evaluated by increasing the laser pulse energy until disbond. A good bond is unaffected by a certain level of stress whereas a weaker one is damaged. The method is shown completely non invasive throughout the whole composite assembly. The sample back surface velocity is measured by an optical interferometer and used to estimate stress history inside the sample. The depth and size of the disbonds are revealed by a post-test inspection by the well established laser-ultrasonic technique. Experimental results show that the proposed method is able to differentiate weak bond from strong bonds and to estimate quantitatively their bond strength.

  18. Influence Coefficients of Constructive Parameters of Meander Slow-Wave System with Additional Shields

    Directory of Open Access Journals (Sweden)

    Metlevskis Edvardas

    2016-12-01

    Full Text Available Constructions of meander slow-wave systems with additional shields grounded at different positions are presented. The construction of meander slow-wave systems with additional shields grounded at both edges is investigated in detail. The influence of the main constructive parameters on the electrical characteristics of meander slow-wave systems with additional shields grounded at both edges is evaluated. The main constructive parameters of the investigated system are: the length of the conductor, the width of meander conductor, the width of additional shield, and the width of the gap between adjacent meander conductors.

  19. Noninvasive respiratory support of juvenile rabbits by high-amplitude bubble continuous positive airway pressure.

    Science.gov (United States)

    Diblasi, Robert M; Zignego, Jay C; Tang, Dennis M; Hildebrandt, Jack; Smith, Charles V; Hansen, Thomas N; Richardson, C Peter

    2010-06-01

    Bubble continuous positive airway pressure (B-CPAP) applies small-amplitude, high-frequency oscillations in airway pressure (DeltaPaw) that may improve gas exchange in infants with respiratory disease. We developed a device, high-amplitude B-CPAP (HAB-CPAP), which provides greater DeltaPaw than B-CPAP provides. We studied the effects of different operational parameters on DeltaPaw and volumes of gas delivered to a mechanical infant lung model. In vivo studies tested the hypothesis that HAB-CPAP provides noninvasive respiratory support greater than that provided by B-CPAP. Lavaged juvenile rabbits were stabilized on ventilator nasal CPAP. The animals were then supported at the same mean airway pressure, bias flow, and fraction of inspired oxygen (FiO2) required for stabilization, whereas the bubbler angle was varied in a randomized crossover design at exit angles, relative to vertical, of 0 (HAB-CPAP0; equivalent to conventional B-CPAP), 90 (HAB-CPAP90), and 135 degrees (HAB-CPAP135). Arterial blood gases and pressure-rate product (PRP) were measured after 15 min at each bubbler angle. Pao2 levels were higher (p<0.007) with HAB-CPAP135 than with conventional B-CPAP. PaCO2 levels did not differ (p=0.073) among the three bubbler configurations. PRP with HAB-CPAP135 were half of the PRP with HAB-CPAP0 or HAB-CPAP90 (p=0.001). These results indicate that HAB-CPAP135 provides greater respiratory support than conventional B-CPAP does.

  20. Short-lived high-amplitude cooling on Svalbard during the Dark Ages

    Science.gov (United States)

    van der Bilt, Willem; D`Andrea, William; Bakke, Jostein; Balascio, Nicholas; Werner, Johannes; Hoek, Wim

    2016-04-01

    As the paradigm of a stable Holocene climate has shifted, an increasing number of high-resolution proxy timeseries reveal dynamic conditions, characterized by high-amplitude climate shifts. Some of these events occurred during historical times and allow us to study the interaction between environmental and cultural change, providing valuable lessons for the near future. These include the Dark Ages Cold Period (DACP) between 300 and 800 AD, a period marked by political upheaval and climate instability that remains poorly investigated. Here, we present two temperature reconstructions from the High Arctic Svalbard Archipelago. To this end, we applied the established alkenone-based UK37 paleothermometer on sediments from two lakes on western Spitsbergen, Lake Hajeren and Lake Hakluyt. The Arctic is presently warming twice as fast as the global average and proxy data as well as model simulations suggest that this amplified response is characteristic for regional climate. The Arctic therefore provides a uniquely sensitive environment to study relatively modest climate shifts, like the DACP, that may not be adequately captured at lower-latitude sites. Owing to undisturbed sediments, a high sampling resolution and robust chronological control, the presented reconstructions resolve the attendant sub-centennial-scale climate shifts. Our findings suggest that the DACP marks a cold spell within the cool Neoglacial period, which started some 4 ka BP on Svalbard. Close investigation reveals a distinct temperature minimum around 500 AD that is reproduced in another alkenone-based temperature reconstruction from a nearby lake. At ± 1.75 °C, cooling underlines the sensitivity of Arctic climate as well as the magnitude of the DACP.

  1. Wind turbine wake meandering at the laboratory and field scales

    Science.gov (United States)

    Heisel, Michael; Musa, Mirko; Hong, Jiarong; Guala, Michele

    2016-11-01

    Flow measurements were collected in the wake of the utility-scale (2.5MW) Eolos wind turbine using a ground-based light detection and ranging (LiDAR) wind profiler to identify the characteristics of wake meandering at the field scale. The investigation seeks to establish the influence of scale and atmospheric turbulence on wake meandering, which has been observed to leave a strong spectral signature on laboratory measurements in wind tunnel and channel flows. The experimental data include multiple test periods at various downstream distances within the turbine wake. Inflow conditions were assessed using a meteorological tower equipped with sonic anemometers. Additionally, an experiment was conducted in the Saint Anthony Falls Laboratory atmospheric boundary layer wind tunnel to provide a direct comparison for the utility-scale results and to reaffirm the findings of previous laboratory-scale investigations. Estimates of the wake and inflow one-dimensional velocity spectra were compared to determine whether wake meandering characteristics are present at both scales. An empirical correction to the velocity spectra of the LiDAR and a few options to extract a more local velocity signal are discussed to compensate for the inherent limitations of LiDAR in capturing turbulent fluctuations.

  2. Plume meander and dispersion in a stable boundary layer

    Science.gov (United States)

    Hiscox, April L.; Miller, David R.; Nappo, Carmen J.

    2010-11-01

    Continuous lidar measurements of elevated plume dispersion and corresponding micrometeorology data are analyzed to establish the relationship between plume behavior and nocturnal boundary layer dynamics. Contrasting nights of data from the JORNADA field campaign in the New Mexico desert are analyzed. The aerosol lidar measurements were used to separate the plume diffusion (plume spread) from plume meander (displacement). Mutiresolution decomposition was used to separate the turbulence scale (90 s). Durations of turbulent kinetic energy stationarity and the wind steadiness were used to characterize the local scale and submesoscale turbulence. Plume meander, driven by submesoscale wind motions, was responsible for most of the total horizontal plume dispersion in weak and variable winds and strong stability. This proportion was reduced in high winds (i.e., >4 m s-1), weakly stable conditions but remained the dominant dispersion mechanism. The remainder of the plume dispersion in all cases was accounted for by internal spread of the plume, which is a small eddy diffusion process driven by turbulence. Turbulence stationarity and the wind steadiness are demonstrated to be closely related to plume diffusion and plume meander, respectively.

  3. Small-Size Meandered Loop Antenna for WLAN Dongle Devices

    Directory of Open Access Journals (Sweden)

    Wen-Shan Chen

    2014-01-01

    Full Text Available This paper proposes a loop-type USB dongle antenna, which is fabricated on a 1.6 mm thick FR-4 substrate for WLAN band systems. The front side of substrate consists of a 50-ohm coaxial line and a multiarm monopole antenna, while the back side has a meandered loop antenna connected to the ground by two via holes. The meandered loop resonates half-wavelength mode at about 2.4 GHz and its higher modes. The higher modes excited by the multiarm monopole form the 5.2 GHz frequency band. The bandwidth of the antenna covers the IEEE802.11 a/b/g WLAN applications. The overall dimensions of the antenna of 30 × 13.75 × 1.6 mm3 with an antenna area of 7.5 × 13.75 mm2 and a planar structure are exactly suitable for applying in dongle devices. The measured results of radiation patterns, antenna gain, and radiation efficiency are also proposed and discussed in the paper.

  4. Bandwidth Enhancement Technique of the Meandered Monopole Antenna

    Directory of Open Access Journals (Sweden)

    Chien-Jen Wang

    2015-01-01

    Full Text Available A small dual-band monopole antenna with coplanar waveguide (CPW feeding structure is presented in this paper. The antenna is composed of a meandered monopole, an extended conductor tail, and an asymmetrical ground plane. Tuning geometrical structure of the ground plane excites an additional resonant frequency band and thus enhances the impedance bandwidth of the meandered monopole antenna. Unlike the conventional monopole antenna, the new resonant mode is excited by a slot trace of the CPW transmission line. The radiation performance of the slot mode is as similar as that of the monopole. The parametrical effect of the size of the one-side ground plane on impedance matching condition has been derived by the simulation. The measured impedance bandwidths, which are defined by the reflection coefficient of −6 dB, are 186 MHz (863–1049 MHz, 19.4% at the lower resonant band and 1320 MHz (1490–2810 MHz, 61.3% at the upper band. From the results of the reflection coefficients of the proposed monopole antenna, the operated bandwidths of the commercial wireless communication systems, such as GSM 900, DCS, IMT-2000, UMTS, WLAN, LTE 2300, and LTE 2500, are covered for uses.

  5. Archimetrics: a quantitative tool to predict three-dimensional meander belt sandbody heterogeneity

    NARCIS (Netherlands)

    van de Lageweg, Wietse I.|info:eu-repo/dai/nl/32298694X; van Dijk, Wout M.|info:eu-repo/dai/nl/322965330; Box, Darren; Kleinhans, Maarten G.|info:eu-repo/dai/nl/217675123

    Fluvial meander belt sediments form some of the most architecturally complex reservoirs in hydrocarbon fields due to multiple scales of heterogeneity inherent in their deposition. Currently, characterization of meander belt bodies largely relies on idealized vertical profiles and a limited number of

  6. Meandering right pulmonary vein associated with severe and progressive "idiopathic-like" pulmonary hypertensive vascular disease.

    Science.gov (United States)

    Cuenca, Sofia; Bret, Montserrat; del Cerro, Maria Jesus

    2016-03-01

    Congenital anomalies of the pulmonary veins are rare. Meandering right pulmonary vein, considered a part of the Scimitar syndrome spectrum, is often an incidental finding during chest imaging. We present the case of a 4-year-old girl diagnosed with meandering pulmonary vein, who developed pulmonary hypertensive disease with an aggressive course, in spite of absence of hypoxia or elevated pulmonary wedge pressure.

  7. Archimetrics: a quantitative tool to predict three-dimensional meander belt sandbody heterogeneity

    NARCIS (Netherlands)

    van de Lageweg, Wietse I.; van Dijk, Wout M.; Box, Darren; Kleinhans, Maarten G.

    2016-01-01

    Fluvial meander belt sediments form some of the most architecturally complex reservoirs in hydrocarbon fields due to multiple scales of heterogeneity inherent in their deposition. Currently, characterization of meander belt bodies largely relies on idealized vertical profiles and a limited number of

  8. Formation of a cohesive floodplain in a dynamic experimental meandering river

    NARCIS (Netherlands)

    Dijk, W.M. van; Lageweg, W.I. van de; Kleinhans, M.G.

    2013-01-01

    Field studies suggest that a cohesive floodplain is a necessary condition for meandering in contrast to braided rivers. However, it is only partly understood how the balance between floodplain construction by overbank deposition and removal by bank erosion and chutes leads to meandering. This is

  9. Meander reconnection method determines restoration success for macroinvertebrate communities in a German lowland river

    DEFF Research Database (Denmark)

    Lorenz, Stefan; Leszinski, Marc; Graeber, Daniel

    2016-01-01

    Re-meandering of degraded rivers is a frequently implemented measure in river restoration. A simple solution is reconnection of old meanders; however, its success likely depends on the reconnection method. We conducted a field study to analyze the benefits of a fully reconnected (fully opened...

  10. Formation of a cohesive floodplain in a dynamic experimental meandering river

    NARCIS (Netherlands)

    Dijk, W.M. van; Lageweg, W.I. van de; Kleinhans, M.G.

    2013-01-01

    Field studies suggest that a cohesive floodplain is a necessary condition for meandering in contrast to braided rivers. However, it is only partly understood how the balance between floodplain construction by overbank deposition and removal by bank erosion and chutes leads to meandering. This is nee

  11. 2D numerical modelling of meandering channel formation

    Indian Academy of Sciences (India)

    Y Xiao; G Zhou; F S Yang

    2016-03-01

    A 2D depth-averaged model for hydrodynamic sediment transport and river morphological adjustment was established. The sediment transport submodel takes into account the influence of non-uniform sediment with bed surface armoring and considers the impact of secondary flow in the direction of bed-loadtransport and transverse slope of the river bed. The bank erosion submodel incorporates a simple simulation method for updating bank geometry during either degradational or aggradational bed evolution. Comparison of the results obtained by the extended model with experimental and field data, and numericalpredictions validate that the proposed model can simulate grain sorting in river bends and duplicate the characteristics of meandering river and its development. The results illustrate that by using its control factors, the improved numerical model can be applied to simulate channel evolution under differentscenarios and improve understanding of patterning processes.

  12. Partial transpose of random quantum states: Exact formulas and meanders

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Motohisa [Zentrum Mathematik, M5, Technische Universitaet Muenchen, Boltzmannstrasse 3, 85748 Garching (Germany); Sniady, Piotr [Zentrum Mathematik, M5, Technische Universitaet Muenchen, Boltzmannstrasse 3, 85748 Garching (Germany); Institute of Mathematics, Polish Academy of Sciences, ul. Sniadeckich 8, 00-956 Warszawa (Poland); Institute of Mathematics, University of Wroclaw, pl. Grunwaldzki 2/4, 50-384 Wroclaw (Poland)

    2013-04-15

    We investigate the asymptotic behavior of the empirical eigenvalues distribution of the partial transpose of a random quantum state. The limiting distribution was previously investigated via Wishart random matrices indirectly (by approximating the matrix of trace 1 by the Wishart matrix of random trace) and shown to be the semicircular distribution or the free difference of two free Poisson distributions, depending on how dimensions of the concerned spaces grow. Our use of Wishart matrices gives exact combinatorial formulas for the moments of the partial transpose of the random state. We find three natural asymptotic regimes in terms of geodesics on the permutation groups. Two of them correspond to the above two cases; the third one turns out to be a new matrix model for the meander polynomials. Moreover, we prove the convergence to the semicircular distribution together with its extreme eigenvalues under weaker assumptions, and show large deviation bound for the latter.

  13. Tsunami intrusion in wide meandering channels: a Lagrangian numerical experiment

    Science.gov (United States)

    Couston, L. A.; Alam, M. R.

    2015-12-01

    Among the many difficulties of tsunami forecast, wave runup on sloped beaches remains a major obstacle in numerical simulations. Traditional Eulerian models must adjust the fluid flow domain continuously due to the moving shorelines, which can significantly affect the computational cost and results accuracy. An efficient though uncommon alternative for accurate runup predictions still exists, consisting in using a Lagrangian model as recently shown by e.g. Couston et al. (2015) who studied the runup of landslide tsunamis in lakes with a non-dispersive Lagrangian model. Here we introduce a fully-nonlinear Boussinesq-type model derived in the Lagrangian framework to investigate various cases of long-wave runup on curved beaches and meandering channels. The governing equations are expressed in terms of curvilinear Lagrangian coordinates, making the model suitable for accurate runup computations at shorelines of arbitrary geometry while retaining the inherent simplicity of a physical model discretized on a fixed and structured grid. We implement an elliptic grid generation algorithm to map the physical space to the computational space, and a high-order finite-difference scheme for time integration. The numerical model has a linear complexity in the number of unknowns when neglecting dispersive effects. We show that the formation of edge waves due to the sloped banks of a wide channel has a significant influence on the capability of a meander or constriction in reflecting the intruding tsunami, and we investigate the effect of dispersion. Reference: Couston, L.-A., Mei, C. C., & Alam, M.-R. (2015). Landslide tsunamis in lakes. Journal of Fluid Mechanics, 772, 784-804.

  14. Meander migration modeling accounting for the effect of riparian vegetation

    Science.gov (United States)

    Eke, E.; Parker, G.

    2010-12-01

    A numerical model is proposed to study the development of meandering rivers so as to reproduce patterns of both migration and spatial/temporal width variation pattern observed in nature. The model comprises of: a) a depth-averaged channel hydrodynamic/morphodynamic model developed using a two-parameter perturbation expansion technique that considers perturbations induced by curvature and spatial channel width variation and b) a bank migration model which separately considers bank erosional and depositional processes. Unlike most previous meandering river models where channel migration is characterized only in terms of bank erosion, channel dynamics are here defined at channel banks which are allowed to migrate independently via deposition/erosion based on the local flow field and bank characteristics. A bank erodes (deposits) if the near bank Shields stress computed from the flow field is greater (less) than a specified threshold. This threshold Shields number is equivalent to the formative Shields stress characterizing bankfull flow. Excessive bank erosion is controlled by means of natural armoring provided by cohesive/rooted slump blocks produced when a stream erodes into the lower non-cohesive part of a composite bank. Bank deposition is largely due to sediment trapping by vegetation; resultant channel narrowing is related to both a natural rate of vegetal encroachment and flow characteristics. This new model allows the channel freedom to vary in width both spatially and in time as it migrates, so accounting for the bi-directional coupling between vegetation and flow dynamics and reproducing more realistic planform geometries. Preliminary results based on the model are presented.

  15. The MACHO Project Sample of Galactic Bulge High-Amplitude Scuti Stars: Pulsation Behavior and Stellar Properties

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, D.P.; Cook, K.H.; Freeman, K.C.; Geha, M.; Griest, K.; Lehner, M.J.; Marshall, S.L.; McNamara, B.J.; Minniti, D.; Nelson, C.; Peterson, B.A.; Popowski, P.; Pratt, M.R.; Quinn, P.J.; Rodgers, A.W.; Sutherland, W.; Templeton, M.R.; Vandehei, T.; Welch, D.L.

    1999-11-16

    We have detected 90 objects with periods and lightcurve structure similar to those of field {delta} Scuti stars, using the Massive Compact Halo Object (MACHO) Project database of Galactic bulge photometry. If we assume similar extinction values for all candidates and absolute magnitudes similar to those of other field high-amplitude {delta} Scuti stars (HADS), the majority of these objects lie in or near the Galactic bulge. At least two of these objects are likely foreground {delta} Scuti stars, one of which may be an evolved nonradial pulsator, similar to other evolved, disk-population {delta} Scuti stars. We have analyzed the light curves of these objects and find that they are similar to the light curves of field {delta} Scuti stars and the {delta} Scuti stars found by the Optical Gravitational Lens Experiment (OGLE). However, the amplitude distribution of these sources lies between those of low- and high-amplitude {delta} Scuti stars, which suggests that they may be an intermediate population. We have found nine double-mode HADS with frequency ratios ranging from 0.75 to 0.79, four probable double- and multiple-mode objects, and another four objects with marginal detections of secondary modes. The low frequencies (5-14 cycles d{sup -1}) and the observed period ratios of {approx}0.77 suggest that the majority of these objects are evolved stars pulsating in fundamental or first overtone radial modes.

  16. Numerical investigation of long-term planform dynamics and stability of river meandering on fluvial floodplains

    Science.gov (United States)

    Xu, Dong; Bai, Yuchuan; Ma, Jianmin; Tan, Yan

    2011-09-01

    A mathematical model for river meandering and floodplain development is presented under the assumption of constant channel width, which combined Johanneson and Parker (1989) linear theory for flows in river bends and a conceptual depositional model from Howard (1992). A new bank erosion model is also developed, which takes into consideration of the nonlinearity in near-bank velocity and the outer bank height. Simulations reproduce the long-term behavior of river meandering and floodplain evolution in a way very similar to their natural processes. Based on the simulation results, stability of river meandering dynamics is discussed and the concept of filtration effect is introduced to highlight meandering rivers' capability to filter out arbitrarily applied planform disturbance. Simulations are also carried out to investigate the influence of the velocity nonlinearity and the outer bank height in bank erosion model, as well as their combinations. Results show that the consideration of velocity nonlinearity in bank erosion model leads to highly upstream-skewing geometry of fully developed river meanders, as well as a slower downstream migration of meander trains. The influence of nonlinearity in bank erosion model is much smaller than the influence of bank height, which reduces the bank migration rate exponentially in the newly introduced bank erosion model. The outer bank height consideration tends to decelerate the downstream migration rate of river meanders and accelerate lateral expansion of the floodplain as well. Consequently, a broader floodplain is generated compared with simulations without bank height considerations.

  17. Comment on "The role of wetting heterogeneities in the meandering instability of a partial wetting rivulet"

    CERN Document Server

    Fathi, Nima; Putkaradze, Vakhtang; Vorobieff, Peter

    2014-01-01

    Rivulets and their meandering on a partially wetting surface present an interesting problem, as complex behavior arises from a deceptively simple setup. Recently Couvreur and Daerr suggested that meandering is caused by an instability developing as the flow rate $Q$ increases to a critical value $Q_c$, with stationary (pinned) meandering being the final state of the flow. We tried to verify this assertion experimentally, but instead produced results contradicting the claim of Couvreur and Daerr. The likely reason behind the discrepancy is the persistence of flow-rate perturbations. Moreover, the theory presented in this paper cannot reproduce the states as considered and disagrees with other theories.

  18. a Linear Model for Meandering Rivers with Arbitrarily Varying Width

    Science.gov (United States)

    Frascati, A.; Lanzoni, S.

    2011-12-01

    Alluvial rivers usually exhibit quite complex planforms, characterized by a wide variety of alternating bends, that have attracted the interest of a large number of researchers. Much less attention has been paid to another striking feature observed in alluvial rivers, namely the relatively regular spatial variations attained by the channel width. Actively meandering channels, in fact, generally undergo spatial oscillations systematically correlated with channel curvature, with cross sections wider at bends than at crossings. Some other streams have been observed to exhibit irregular width variations. Conversely, rivers flowing in highly vegetated flood plains, i.e. canaliform rivers, may exhibit an opposite behavior, owing to the combined effects of bank erodibility and floodplain depositional processes which, in turn, are strictly linked to vegetation cover. Similarly to streamline curvatures induced by bends, the presence of along channel width variations may have remarkable effects on the flow field and sediment dynamics and, thereby, on the equilibrium river bed configuration. In particular, spatial distribution of channel curvature typically determines the formation of a rhythmic bar-pool pattern in the channel bed strictly associated with the development of river meanders. Channel width variations are on the contrary characterized by a sequence of narrowing, yielding a central scour, alternated to the downstream development of a widening associated with the formation of a central bar. Here we present a morphodynamic model that predict at a linear level the spatial distribution of the flow field and the equilibrium bed configuration of an alluvial river characterized by arbitrary along channel distributions of both the channel axis curvature and the channel width. The mathematical model is averaged over the depth and describes the steady, non-uniform flow and sediment transport in sinuous channels with a noncohesive bed. The governing two-dimensional equations

  19. High-amplitude THz and GHz strain waves, generated by ultrafast screening of piezoelectric fields in InGaN/GaN multiple quantum wells

    DEFF Research Database (Denmark)

    Porte, Henrik; van Capel, P.J.S.; Turchinovich, Dmitry

    2010-01-01

    Screening of large built-in piezoelectric fields in InGaN/GaN quantum wells leads to high-amplitude acoustic emission. We will compare acoustic emission by quantum wells with different thicknesses with photoluminescence; indicating screening.......Screening of large built-in piezoelectric fields in InGaN/GaN quantum wells leads to high-amplitude acoustic emission. We will compare acoustic emission by quantum wells with different thicknesses with photoluminescence; indicating screening....

  20. Mechanical Stress Effects on Electromigration Voiding in a Meandering Test Stripe

    Science.gov (United States)

    Lowry, L. E.; Tai, B. H.; Mattila, J.; Walsh, L. H.

    1993-01-01

    Earlier experimental findings concluded that electromigratin voids in these meandering stripe test structures were not randomly distributed and that void nucleation frequenly occurred sub-surface at the metal/thermal oxide interface.

  1. Meander reconnection method determines restoration success for macroinvertebrate communities in a German lowland river

    DEFF Research Database (Denmark)

    Lorenz, Stefan; Leszinski, Marc; Graeber, Daniel

    2016-01-01

    Re-meandering of degraded rivers is a frequently implemented measure in river restoration. A simple solution is reconnection of old meanders; however, its success likely depends on the reconnection method. We conducted a field study to analyze the benefits of a fully reconnected (fully opened...... sufficiently affect the basic hydromorphological requirements to achieve reference macroinvertebrate community composition. Measures including hydromorphological conditions are therefore recommended for employment in environmental management....

  2. Optimization of meander line radiators for frequency selective surfaces by using genetic algorithm

    Science.gov (United States)

    Bucuci, Stefania C.; Dumitrascu, Ana; Danisor, Alin; Berescu, Serban; Tamas, Razvan D.

    2015-02-01

    In this paper we propose the use of frequency selective surfaces based on meander line radiators, as targets for monitoring slow displacements with synthetic aperture radars. The optimization of the radiators is performed by using genetic algorithms on only two parameters i.e., gain and size. As an example, we have optimized a single meander antenna, resonating in the X-band, at 9.65 GHz.

  3. Changes in morphometric meander parameters identified on the Karoon River, Iran, using remote sensing data

    Science.gov (United States)

    Yousefi, Saleh; Pourghasemi, Hamid Reza; Hooke, Janet; Navratil, Oldrich; Kidová, Anna

    2016-10-01

    River meander dynamics and mobility are important indicators of environmental change related to climate changes and anthropogenic activities at local and river basin scales. The aim of the present study is to identify morphological changes of the Karoon River in Iran using high accuracy maps and Landsat satellite images by analyses during the time period 1989-2008. In this study, 20 meandering reaches were analyzed over a 128-km-long river reach located in the middle part of the Karoon River, Iran. Morphometric indicators such as: river width (W), meander neck length (L), axis length (A), radius of curvature (R), water flow length (S), and sinuosity of meander (C) were extracted for the identified meanders. The results of a paired t-test showed that river width (W) and meander neck length (L) have significantly changed during the study period (1989-2008), with an increase of + 3.5 m for W and a decrease of 274 m for L. Spearman correlation analysis has shown that meander parameter changes are highly correlated to each other. The parameters that do not have significant correlation together are C with W and L, W and L, and L with S and A. During the period of the study, the flow length and river sinuosity decreased for the whole river reach, by 4.77 km and 0.11, respectively. Analysis of land use/land cover categories (1989 and 2008) using the support vector machine (SVM) and kernel function method served as one of the tools for interpretation of the meander parameter changes. These changes can be attributed not only to LU/LC (riparian vegetation to agriculture area ratio) but also to dam construction in the upstream part of the river that leads to major hydrological regime and sediment transfer alteration. Sediment extraction may also be an important factor.

  4. Effect of nacelle on the wake meandering in Horns Rev wind farm

    Science.gov (United States)

    Yang, Xiaolei; Foti, Daniel; Sotiropoulos, Fotis

    2016-11-01

    Turbine wake meandering has considerable effects on the velocity deficit and turbulence intensity in the wake. However, the mechanism for wake meandering is still not well understood and low-order models cannot take into account the wake meandering effects accurately. A recent work by Kang, Yang and Sotiropoulos showed that the nacelle has a significant effect on the wake meandering of a hydrokinetic turbine. To examine the nacelle contributions to wake meandering and wake interactions in utility-scale wind farms, we simulate the atmospheric turbulent flow over the Horns Rev wind farm using large-eddy simulation with actuator type models. In a preliminary simulation on a coarse grid using actuator line model for turbine blades without a nacelle model, the computed power shows overall good agreement with field measurements. Fine grid simulations using an actuator surface model for turbine blades with and without a nacelle model are being carried out. The corresponding results will be presented with analysis on wake meandering dynamics using the technique proposed by Horward et al. and Foti et al.. This work was supported by DOE (DE-AC04-94AL85000), Xcel Energy (Grant RD4-13) and Sandia National Laboratories. Computational resources were provided by National Renewable Energy Laboratory and University of Minnesota Supercomputing Institute.

  5. Meandering worms: mechanics of undulatory burrowing in muds.

    Science.gov (United States)

    Dorgan, Kelly M; Law, Chris J; Rouse, Greg W

    2013-04-22

    Recent work has shown that muddy sediments are elastic solids through which animals extend burrows by fracture, whereas non-cohesive granular sands fluidize around some burrowers. These different mechanical responses are reflected in the morphologies and behaviours of their respective inhabitants. However, Armandia brevis, a mud-burrowing opheliid polychaete, lacks an expansible anterior consistent with fracturing mud, and instead uses undulatory movements similar to those of sandfish lizards that fluidize desert sands. Here, we show that A. brevis neither fractures nor fluidizes sediments, but instead uses a third mechanism, plastically rearranging sediment grains to create a burrow. The curvature of the undulating body fits meander geometry used to describe rivers, and changes in curvature driven by muscle contraction are similar for swimming and burrowing worms, indicating that the same gait is used in both sediments and water. Large calculated friction forces for undulatory burrowers suggest that sediment mechanics affect undulatory and peristaltic burrowers differently; undulatory burrowing may be more effective for small worms that live in sediments not compacted or cohesive enough to extend burrows by fracture.

  6. Nano-structural characteristics of carbon nanotube-polymer composite films for high-amplitude optoacoustic generation

    Science.gov (United States)

    Baac, Hyoung Won; Ok, Jong G.; Lee, Taehwa; Jay Guo, L.

    2015-08-01

    We demonstrate nano-structural characteristics of carbon nanotube (CNT)-polydimethylsiloxane (PDMS) composite films that can be used as highly efficient and robust ultrasound transmitters for diagnostic and therapeutic applications. An inherent architecture of the nano-composite provides unique thermal, optical, and mechanical properties that are accommodated not just for efficient energy conversion but also for extraordinary robustness against pulsed laser ablation. First, we explain a thermoacoustic transfer mechanism within the nano-composite. CNT morphologies are examined to determine a suitable arrangement for heat transfer to the surrounding PDMS. Next, we introduce an approach to enhance optical extinction of the composite films, which uses shadowed deposition of a thin Au layer through an as-grown CNT network. Finally, the transmitter robustness is quantified in terms of laser-induced damage threshold. This reveals that the CNT-PDMS films can withstand an order-of-magnitude higher optical fluence (and extinction) than a Cr film used as a reference. Such robustness is crucial to increase the maximum-available optical energy for optoacoustic excitation and pressure generation. All of these structure-originated characteristics manifest the CNT-PDMS composite films as excellent optoacoustic transmitters for high-amplitude and high-frequency ultrasound generation.

  7. Nano-structural characteristics of carbon nanotube-polymer composite films for high-amplitude optoacoustic generation.

    Science.gov (United States)

    Baac, Hyoung Won; Ok, Jong G; Lee, Taehwa; Guo, L Jay

    2015-09-14

    We demonstrate nano-structural characteristics of carbon nanotube (CNT)-polydimethylsiloxane (PDMS) composite films that can be used as highly efficient and robust ultrasound transmitters for diagnostic and therapeutic applications. An inherent architecture of the nano-composite provides unique thermal, optical, and mechanical properties that are accommodated not just for efficient energy conversion but also for extraordinary robustness against pulsed laser ablation. First, we explain a thermoacoustic transfer mechanism within the nano-composite. CNT morphologies are examined to determine a suitable arrangement for heat transfer to the surrounding PDMS. Next, we introduce an approach to enhance optical extinction of the composite films, which uses shadowed deposition of a thin Au layer through an as-grown CNT network. Finally, the transmitter robustness is quantified in terms of laser-induced damage threshold. This reveals that the CNT-PDMS films can withstand an order-of-magnitude higher optical fluence (and extinction) than a Cr film used as a reference. Such robustness is crucial to increase the maximum-available optical energy for optoacoustic excitation and pressure generation. All of these structure-originated characteristics manifest the CNT-PDMS composite films as excellent optoacoustic transmitters for high-amplitude and high-frequency ultrasound generation.

  8. A photometric monitoring of bright high-amplitude delta Scuti stars. II. Period updates for seven stars

    CERN Document Server

    Derekas, A; Székely, P; Alfaro, E J; Csák, B; Mészáros, S; Rodríguez, E; Rolland, A; Sarneczky, K; Szabó, G M; Szatmary, K; Varadi, M; Kiss, C; Meszaros, Sz.; Szabo, Gy.M.; Kiss, Cs.

    2003-01-01

    We present new photometric data for seven high-amplitude delta Scuti stars. The observations were acquired between 1996 and 2002, mostly in the Johnson photometric system. For one star (GW UMa), our observations are the first since the discovery of its pulsational nature from the Hipparcos data.The primary goal of this project was to update our knowledge on the period variations of the target stars. For this, we have collected all available photometric observations from the literature and constructed decades-long O-C diagrams of the stars. This traditional method is useful because of the single-periodic nature of the light variations. Text-book examples of slow period evolution (XX Cyg, DY Her, DY Peg) and cyclic period changes due to light-time effect (LITE) in a binary system (SZ Lyn) are updated with the new observations. For YZ Boo, we find a period decrease instead of increase. The previously suggested LITE-solution of BE Lyn (Kiss & Szatmary 1995) is not supported with the new O-C diagram. Instead o...

  9. Temporal variation of meandering intensity and domain-wide lateral oscillations of the Gulf Stream

    Science.gov (United States)

    Lee, Tong; Cornillon, Peter

    1995-01-01

    The path of the Gulf Stream exhibits two modes of variability: wavelike spatial meanders associated with instability processes and large-sale lateral shifts of the path presumably due to atmospheric forcing. The objectives of this study are to examine the temporal variation of the intensity of spatial meandering in the stream, to characterize large-scale lateral oscillations in the stream's path, and to study the correlation betwen these two dynamically distinct modes of variability. The data used for this analysis are path displacemets ofthe Gulf Stream between 75 deg and 60 deg W obtained from AVHRR-derived (Advanced Very High Resolution Radiometer) infrared images for the period April 1982 through December 1989. Meandering intensity, measured by the spatial root-mean-sqaure displacement of the stream path, displays a 9-month dominant periodicity which is persistent through the study period. The 9-month fluctuation in meandering intensity may be related to the interaction of Rosseby waves with the stream. Interannual variation of meandering intensity is also found to be significant, with meandering being mich more intense during 1985 than it was in 1987. Annual variation, however,is weak and not well-defined.The spatially averaged position of the stream, which reflects nonmeandering large-scale lateral oscillations of the stream path, is dominated by an annual cycle. On average, the mean position is farthest north in November and farthest south in April. The first empirical orthogonal function mode of the space-time path displacements represents lateral oscillatins that are in-phase over the space-time domain. Interannual oscillations are also observed and are found to be weaker than the annual oscillation. The eigenvalue of the first mode indicates that about 21.5% of the total space-time variability of the stream path can be attibuted to domain-wide lateral oscillation. The correlation between meandering intensity and domain-wide lateral oscillations is very

  10. Fluvial bar dynamics in large meandering rivers with different sediment supply in the Amazon River basin

    Science.gov (United States)

    Monegaglia, Federico; Zolezzi, Guido; Tubino, Marco; Henshaw, Alex

    2017-04-01

    Sediments in the large meandering rivers of the Amazon basin are known to be supplied by sources providing highly different magnitudes of sediment input and storage, ranging from the sediment-rich Andean region to the sediment-poor Central Trough. Recent observations have highlighted how such differences in sediment supply have an important, net effect on the rates of planform activity of meandering rivers in the basin, in terms of meander migration and frequency of cutoffs. In this work we quantify and discuss the effect of sediment supply on the organization of macroscale sediment bedforms on several large meandering rivers in the Amazon basin, and we link our findings with those regarding the rates of planform activity. Our analysis is conducted through the newly developed software PyRIS, which enables us to perform extensive multitemporal analysis of river morphodynamics from multispectral remotely sensed Landsat imagery in a fully automated fashion. We show that large rivers with low sediment supply tend to develop alternate bars that consistently migrate through long reaches, characterized at the same time by limited planform development. On the contrary, high sediment supply is associated with the development of point bars that are well-attached to the evolving meander bends and that follow temporal oscillations around the bend apexes, which in turn show rapid evlution towards complex meander shapes. Finally, rivers with intermediate rates of sediment supply develop rather steady point bars associated with slowly migrating, regular meanders. We finally discuss the results of the image analysis in the light of the properties of river planform metrics (like channel curvature and width) for the examined classes of river reaches with different sediment supply rates.

  11. Comparing the Planform Morphologies of a Freely Meandering Channel and the Bedrock- Controlled South River, VA.

    Science.gov (United States)

    Narinesingh, P.; Pizzuto, J.

    2008-12-01

    The planforms of the lithologically controlled South River, VA, and the freely meandering Teklanika River, AK were investigated using two statistical methods as well as fractal and spectral analyses. The lithologic controls along the South River include riverbanks consisting of pre-Holocene terraces and alluvial fans, and highly resistant bedrock that frequently crops out both in the bed and along the banks. A statistical analysis of bends composed of single arcs shows that the average radius of curvature is six times greater and the average bend length is 25 percent smaller for the South River relative to the meandering river, indicating that lithologically controlled bends are less curved and shorter than freely-formed meander bends. Fractal analysis reveals that the meandering river displays a smaller range in length scales than the South River, which exhibits a wider range in length scales that reflect a wider distribution of bend sizes. The method of Lancaster and Bras, (2002), which identifies bends of different complexity, indicates that the meandering river displays bends composed of single arcs, complex arcs and multiple complex arcs. Unlike the freely meandering Teklanika River, the lithologically controlled South River does not display bends composed of multiple complex arcs, though bends composed of single and complex arcs are common. Spectral analysis reveals that the meandering river's pattern is composed of a relatively narrow range of dominant wavelengths with the most prominent wavelength being the longest, while the lithologically controlled river displays dominant wavelengths over a relatively wide range and the most prominent wavelength is not the longest. This analysis demonstrates that lithological controls increase the range of bend lengths, increase radii of curvature, simplify bend shapes, and increase the distribution of wavelengths of sinuous rivers.

  12. An integrated approach to investigate the reach-averaged bend scale dynamics of large meandering rivers

    Science.gov (United States)

    Monegaglia, Federico; Henshaw, Alex; Zolezzi, Guido; Tubino, Marco

    2016-04-01

    Planform development of evolving meander bends is a beautiful and complex dynamic phenomenon, controlled by the interplay among hydrodynamics, sediments and floodplain characteristics. In the past decades, morphodynamic models of river meandering have provided a thorough understanding of the unit physical processes interacting at the reach scale during meander planform evolution. On the other hand, recent years have seen advances in satellite geosciences able to provide data with increasing resolution and earth coverage, which are becoming an important tool for studying and managing river systems. Analysis of the planform development of meandering rivers through Landsat satellite imagery have been provided in very recent works. Methodologies for the objective and automatic extraction of key river development metrics from multi-temporal satellite images have been proposed though often limited to the extraction of channel centerlines, and not always able to yield quantitative data on channel width, migration rates and bed morphology. Overcoming such gap would make a major step forward to integrate morphodynamic theories, models and real-world data for an increased understanding of meandering river dynamics. In order to fulfill such gaps, a novel automatic procedure for extracting and analyzing the topography and planform dynamics of meandering rivers through time from satellite images is implemented. A robust algorithm able to compute channel centerline in complex contexts such as the presence of channel bifurcations and anabranching structures is used. As a case study, the procedure is applied to the Landsat database for a reach of the well-known case of Rio Beni, a large, suspended load dominated, tropical meandering river flowing through the Bolivian Amazon Basin. The reach-averaged evolution of single bends along Rio Beni over a 30 years period is analyzed, in terms of bend amplification rates computed according to the local centerline migration rate. A

  13. Competing growth processes induced by next-nearest-neighbor interactions: Effects on meandering wavelength and stiffness

    Science.gov (United States)

    Blel, Sonia; Hamouda, Ajmi BH.; Mahjoub, B.; Einstein, T. L.

    2017-02-01

    In this paper we explore the meandering instability of vicinal steps with a kinetic Monte Carlo simulations (kMC) model including the attractive next-nearest-neighbor (NNN) interactions. kMC simulations show that increase of the NNN interaction strength leads to considerable reduction of the meandering wavelength and to weaker dependence of the wavelength on the deposition rate F. The dependences of the meandering wavelength on the temperature and the deposition rate obtained with simulations are in good quantitative agreement with the experimental result on the meandering instability of Cu(0 2 24) [T. Maroutian et al., Phys. Rev. B 64, 165401 (2001), 10.1103/PhysRevB.64.165401]. The effective step stiffness is found to depend not only on the strength of NNN interactions and the Ehrlich-Schwoebel barrier, but also on F. We argue that attractive NNN interactions intensify the incorporation of adatoms at step edges and enhance step roughening. Competition between NNN and nearest-neighbor interactions results in an alternative form of meandering instability which we call "roughening-limited" growth, rather than attachment-detachment-limited growth that governs the Bales-Zangwill instability. The computed effective wavelength and the effective stiffness behave as λeff˜F-q and β˜eff˜F-p , respectively, with q ≈p /2 .

  14. Interactions between hyporheic flow produced by stream meanders, bars, and dunes

    Science.gov (United States)

    Stonedahl, Susa H.; Harvey, Judson W.; Packman, Aaron I.

    2013-01-01

    Stream channel morphology from grain-scale roughness to large meanders drives hyporheic exchange flow. In practice, it is difficult to model hyporheic flow over the wide spectrum of topographic features typically found in rivers. As a result, many studies only characterize isolated exchange processes at a single spatial scale. In this work, we simulated hyporheic flows induced by a range of geomorphic features including meanders, bars and dunes in sand bed streams. Twenty cases were examined with 5 degrees of river meandering. Each meandering river model was run initially without any small topographic features. Models were run again after superimposing only bars and then only dunes, and then run a final time after including all scales of topographic features. This allowed us to investigate the relative importance and interactions between flows induced by different scales of topography. We found that dunes typically contributed more to hyporheic exchange than bars and meanders. Furthermore, our simulations show that the volume of water exchanged and the distributions of hyporheic residence times resulting from various scales of topographic features are close to, but not linearly additive. These findings can potentially be used to develop scaling laws for hyporheic flow that can be widely applied in streams and rivers.

  15. Application of meandering centreline migration modelling and object-based approach of Long Nab member

    Science.gov (United States)

    Saadi, Saad

    2017-04-01

    Characterizing the complexity and heterogeneity of the geometries and deposits in meandering river system is an important concern for the reservoir modelling of fluvial environments. Re-examination of the Long Nab member in the Scalby formation of the Ravenscar Group (Yorkshire, UK), integrating digital outcrop data and forward modelling approaches, will lead to a geologically realistic numerical model of the meandering river geometry. The methodology is based on extracting geostatistics from modern analogous, meandering rivers that exemplify both the confined and non-confined meandering point bars deposits and morphodynamics of Long Nab member. The parameters derived from the modern systems (i.e. channel width, amplitude, radius of curvature, sinuosity, wavelength, channel length and migration rate) are used as a statistical control for the forward simulation and resulting object oriented channel models. The statistical data derived from the modern analogues is multi-dimensional in nature, making analysis difficult. We apply data mining techniques such as parallel coordinates to investigate and identify the important relationships within the modern analogue data, which can then be used drive the development of, and as input to the forward model. This work will increase our understanding of meandering river morphodynamics, planform architecture and stratigraphic signature of various fluvial deposits and features. We will then use these forward modelling based channel objects to build reservoir models, and compare the behaviour of the forward modelled channels with traditional object modelling in hydrocarbon flow simulations.

  16. Modelling the equilibrium bed topography of submarine meanders that exhibit reversed secondary flows

    Science.gov (United States)

    Darby, Stephen E.; Peakall, Jeff

    2012-08-01

    Submarine meandering channels formed by turbidity currents are common; however, their location on the ocean floor and their inactive status make it difficult to measure process dynamics and bed morphology. Conceptual models have, therefore, instead been developed by analogy with the well understood mechanics of fluvial bends. However, unlike fluvial currents, in turbidity currents the downstream velocity maximum typically occurs near the bed and recent experimental and theoretical studies suggest that, under certain hydraulic and morphological conditions, this forces the secondary flow to exhibit the reverse sense to that encountered in fluvial bends. Herein the possible morphological implications of a reversal of secondary flow are explored by modelling the force balance on sediment grains moving through either (i) field and laboratory submarine meander bends that are known to exhibit ‘reversed' secondary flows, or (ii) inactive submarine meander bends where the nature of the secondary flow in the formative turbidity currents can be inferred to be reversed. Exploratory simulations are undertaken for a single hypothetical submarine bend with morphological properties based on nine relic meanders observed on the floor of the Gulf of Alaska. Reconstructions of secondary flow properties within the Gulf of Alaska bends indicate that they likely exhibited reversed secondary flows. Results of the exploratory simulations indicate that, unlike typical fluvial meanders, the transverse bed profile gradient of the hypothetical bend is very low and the point bar is located downstream of the bend apex.

  17. Migration and cutoff of meanders in the hyperarid environment of the middle Tarim River, northwestern China

    Science.gov (United States)

    Li, Zhiwei; Yu, Guo-An; Brierley, Gary John; Wang, Zhaoyin; Jia, Yanhong

    2017-01-01

    A meandering channel has developed in the middle Tarim River, the longest inland river flowing through a hyperarid environment in northwestern China. Although the drainage basin of the Tarim River extends over 1 million km2, flow in downstream reaches is largely restricted to summer months, and irrigation pressures have made the flood season increasingly short. The planform morphology, lateral migration rate, and cutoffs of 105 meanders were analysed using multiperiod remote sensing images and field survey analyses of channel bed and bank properties and of riparian vegetation cover. Results show that planform attributes of the meandering Tarim River are similar to those found in other environments. The ratio of the channel centreline length to the neck channel width of meanders ranges between 1.2 and 8.1, the bend curvature (ratio of bend radius to channel width) ranges between 0.30 and 2.8, and the average deflection angle of the bend apexes is 79.9°. Meander migration rates range from 1.4 to 96.7 m y- 1. From 2000 to 2013, 45 cutoffs occurred along the 400-km-long reach. As the riparian vegetation cover is sparse because of limited precipitation and because banks are comprised of dense roots, fine sand and silt materials, but lack clay, bank strength is limited and presents limited constraints upon bend movement.

  18. Georectification of historical aerial photos to track meander change in Wood River, Klamath County, Oregon

    Science.gov (United States)

    Nash, C.; Hughes, M. L.

    2010-12-01

    The Wood River in Oregon’s Upper Klamath Basin is a meandering channel draining the southeastern slopes of Crater Lake National Park. Its valley floor is heavily grazed and highly altered by a series of irrigation channels that have substantially affected the river’s spring-fed flow regime and morphology. Despite efforts to restore the river’s hydrology, very little information is available about the river’s geomorphology. Using high-resolution LIDAR data from 2004 and georectified aerial photos from 1940-2009, we analyzed meander changes along the Wood River in the geomorphic context of its valley floor and meander belt. Aerial photos were scanned to produce digital images with sub-meter pixels, then georectified with a second-order polynomial transformation. Nine or fewer ground-control points were used for each photo to achieve an overall root-mean-square error value of 0.6 - 0.7 m. The scarcity of buildings and changes in the road and fence networks over the study period required the partial use of “natural pattern matching” during photo rectification. Semi-permanent patterns of fan erosion on the upper valley floor and hydrogeomorphic wetland patterns in lower valley provided the primary bases for natural pattern matching, further aided by the use of transparency during photo overlaying. Six prototypes of meander change were identified: extension, compression, translation, rotation, compound heading, and cutoff. Of these types, extension of meanders was the most frequently occurring. However, the effects of extension were counteracted by numerous meander cutoffs, which nominally affected sinuosity, but actually shortened the channel by about 1 km, or about 3%. Cutoffs were most frequent in the upper reaches of the river, where valley slope is higher, the meander belt is wider, and accommodation space was adequate to promote relatively high initial sinuosity. In these reaches, some cutoffs appear to have initiated downstream transfers of bedload

  19. EXPERIMENTAL STUDY ON THE RELATION OF BED MORPHOLOGY WITH SURFACE FLOW IN MEANDER CHANNELS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Alternate bars have the property that they migrate downstream whenever floods occur. However,in meander channels whose bend angles are larger than a critical value, the migration of bars can be suppressed, and the positions of bank erosion and flood attack also will be steady. In this study, the bed morphology in flume channels with bends of various lengths and angles is investigated at various flow discharges, and the relation of bed morphology to surface flow is investigated in detail using fluid measuring software. An effort is made to obtain guidelines for the plane shape design of meander channels. Based on the experimental results of bed topography and measurement of surface flow direction and velocity distribution, from the viewpoint of bank erosion and the concentration and dispersion of flood flow the most suitable plane shape for meandering channels is suggested through which the migration of alternate bars is suppressed.

  20. Offshore and onshore wind turbine wake meandering studied in an ABL wind tunnel

    DEFF Research Database (Denmark)

    Barlas, Emre; Buckingham, Sophia; Glabeke, Gertjan;

    2015-01-01

    diameter downstream. The results show an earlier wake recovery for the onshore case. The effect of inflow conditions and the wind turbine’s working conditions on wake meandering was investigated. Wake meandering was detected by hot wire anemometry through a low frequency peak in the turbulent power......Scaled wind turbine models have been installed in the VKI L1-B atmospheric boundary layer wind tunnel at offshore and onshore conditions. Time-resolved measurements were carried out with three component hot wire anemometry and stereo-PIV in the middle vertical plane of the wake up to eleven turbine...... spectrum, present in the entire wake mainly for offshore inflow condition. It was found that the Strouhal number, based on the rotor diameter and the wind velocity at hub height, was in the order of 0.25. Below the meandering frequency, turbulence power spectrum decreased, whereas above it increased. Wake...

  1. Streambed and water profile response to in-channel restoration structures in a laboratory meandering stream

    Science.gov (United States)

    Han, Bangshuai; Chu, Hong-Hanh; Endreny, Theodore A.

    2015-11-01

    In-channel structures are often installed in alluvial rivers during restoration to steer currents, but they also modify the streambed morphology and water surface profile, and alter hydraulic gradients driving ecologically important hyporheic exchange. Although river features before and after restoration need to be compared, few studies have collected detailed observations to facilitate this comparison. We created a laboratory mobile-bed alluvial meandering river and collected detailed measurements in the highly sinuous meander before and after installation of in-channel structures, which included one cross vane and six J-hooks situated along 1 bar unit. Measurements of streambed and water surface elevation with submillimeter vertical accuracy and horizontal resolution were obtained using close-range photogrammetry. Compared to the smooth gradually varied water surface profile for control runs without structures, the structures created rapidly varied flow with subcritical to supercritical flow transitions, as well as backwater and forced-morphology pools, which increased volumetric storage by 74% in the entire stream reach. The J-hooks, located along the outer bank of the meander bend and downstream of the cross vane, created stepwise patterns in the streambed and water surface longitudinal profiles. The pooling of water behind the cross vane increased the hydraulic gradient across the meander neck by 1% and increased local groundwater gradients by 4%, with smaller increases across other transects through the intrameander zone. Scour pools developed downstream of the cross vane and around the J-hooks situated near the meander apex. In-channel structures significantly changed meander bend hydraulic gradients, and the detailed streambed and water surface 3-D maps provide valuable data for computational modeling of changes to hyporheic exchange.

  2. Dynamical studies of the Mersa Matruh Gyre: intense meander and ring formation events

    Science.gov (United States)

    Golnaraghi, Maryam

    A study of the dynamics of the Mersa Matruh Gyre and the Mid-Mediterranean Jet flow system in the southwestern Levantine basin is presented. Data-driven simulations in the Levantine basin, using an eddy-resolving quasigeostrophic model initialized with two quasi-synoptic hydrographic data sets, reveal intense mesoscale meander and ring formation events involving the Mid-Mediterranean Jet, the Mersa Matruh Gyre and the Rhodes Gyre. The dynamics of these events are quantified via local energy and vorticity budget analyses. The dominant processes are investigated and compared with previously studied events in the Gulf Stream Ring and Meander region.

  3. Design of Meander-Line Antennas for Radio Frequency Identification Based on Multiobjective Optimization

    Directory of Open Access Journals (Sweden)

    X. L. Travassos

    2012-01-01

    Full Text Available This paper presents optimization problem formulations to design meander-line antennas for passive UHF radio frequency identification tags based on given specifications of input impedance, frequency range, and geometric constraints. In this application, there is a need for directive transponders to select properly the target tag, which in turn must be ideally isotropic. The design of an effective meander-line antenna for RFID purposes requires balancing geometrical characteristics with the microchip impedance. Therefore, there is an issue of optimization in determining the antenna parameters for best performance. The antenna is analyzed by a method of moments. Some results using a deterministic optimization algorithm are shown.

  4. A new delirium phenotype with rapid high amplitude onset and nearly as rapid reversal: Central Coast Australia Delirium Intervention Study

    Directory of Open Access Journals (Sweden)

    Regal PJ

    2015-02-01

    , and 45%/80% for the Delirium Index. General medicine and geriatric medicine groups had similar outcomes.Conclusion: This delirium phenotype selects for a rapid high amplitude critical decline in attention, executive function, IADL, and apathy that recovers almost as rapidly.Keywords: delirium, inattention, executive function, dementia

  5. A numerical investigation of the role of the turbine rotor scale and the nacelle on wake meandering

    Science.gov (United States)

    Foti, Daniel; Yang, Xiaolei; Shen, Lian; Sotiropoulos, Fotis

    2016-11-01

    Recent analysis of a hydrokinetic turbine and laboratory scale wind turbine reveal that the turbine nacelle has a considerable effect on the turbulence kinetic energy and wake meandering. However, the role of the nacelle on wake meandering for utility-scale wind turbines has not been fully investigated. In this work, a numerical investigation using large eddy simulations of four wind turbines with rotor diameters ranging from laboratory to utility scale reveals similar turbulent structures in the far wake and a comparable wake meandering Strouhal number regardless of rotor size. By reconstructing the wake meandering with three dimensional spatio-temporal filtering process, first proposed in Foti et al., the statistics of the dynamics of the wake meandering are quantified in terms of amplitude and wavelength. Results indicate that the wavelength of wake meandering can be properly scaled by rotor diameter of the turbines for both simulations with and without a nacelle model. The meandering amplitude, on the other hand, is larger for the simulation with a nacelle. This is further quantitative evidence that a nacelle model is imperative to accurately capturing wake meandering. This work was supported by Department of Energy (DE-EE0002980, DE-EE0005482 and DE-AC04-94AL85000), and Sandia National Laboratories.

  6. Meandering instability of air flow in a granular bed: self-similarity and fluid-solid duality

    CERN Document Server

    Yoshimura, Yuki; Okumura, Ko

    2016-01-01

    Meandering instability is familiar to everyone through river meandering or small rivulets of rain flowing down a windshield. However, its physical understanding is still premature, although it could inspire researchers in various fields, such as nonlinear science, fluid mechanics and geophysics, to resolve their long-standing problems. Here, we perform a small-scale experiment in which air flow is created in a thin granular bed to successfully find a meandering regime, together with other remarkable fluidized regimes, such as a turbulent regime. We discover that phase diagrams of the flow regimes for different types of grains can be universally presented as functions of the flow rate and the granular-bed thickness when the two quantities are properly renormalized. We further reveal that the meandering shapes are self-similar as was shown for meandering rivers. The experimental findings are explained by theory, with elucidating the physics. The theory is based on force balance, a minimum-dissipation principle,...

  7. Three dimensional computation of turbulent flow in meandering channels

    Energy Technology Data Exchange (ETDEWEB)

    Van Thinh Nguyen

    2000-07-01

    In this study a finite element calculation procedure together with two-equation turbulent model k-{epsilon} and mixing length are applied to the problem of simulating 3D turbulent flow in closed and open meandering channels. Near the wall a special approach is applied in order to overcome the weakness of the standard k-{epsilon} in the viscous sub-layer. A specialized shape function is used in the special near wall elements to capture accurately the strong variations of the mean flow variables in the viscosity-affected near wall region. Based on the analogy of water and air flows, a few characteristics of hydraulic problems can be examined in aerodynamic models, respectively. To study the relationships between an aerodynamic and a hydraulic model many experiments have been carried out by Federal Waterway Engineering and Research Institute of Karlsruhe, Germany. In order to test and examine the results of these physical models, an appropriated numerical model is necessary. The numerical mean will capture the limitations of the experimental setup. The similarity and the difference between an aerodynamic and a hydraulic model will be found out by the results of numerical computations and will be depicted in this study. Despite the presence of similarities between the flow in closed channels and the flow in open channels, it should be stated that the presence of a free surface in the open channel introduces serious complications to three dimensional computation. A new unknown, which represents the position of nodes on this free surface, is introduced. A special approach is required for solving this unknown. A procedure surface tracking is applied to the free surface boundary like a moving boundary. Grid nodes on the free surface are free to move in such a way that they belong to the spines, which are the generator lines to define the allowed motion of the nodes on the free surface. (orig.) [German] Die numerische Simulation ist heute ein wichtiges Hilfsmittel fuer die

  8. Calibration and Validation of the Dynamic Wake Meandering Model for Implementation in an Aeroelastic Code

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge; Larsen, Gunner Chr.; Larsen, Torben J.;

    2010-01-01

    on this background, and the basic physical mechanisms in the wake—i.e., the velocity deficit, the meandering of the deficit, and the added turbulence—are modeled as simply as possible in order to make fast computations. In the present paper, the DWM model is presented in a version suitable for full integration...

  9. Wake meandering under non-neutral atmospheric stability conditions – theory and facts

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Machefaux, Ewan; Chougule, Abhijit S.

    2015-01-01

    This paper deals with modelling of wake dynamics under influence of atmospheric stability conditions different from neutral. In particular, it is investigated how the basic split in turbulent scales, on which the Dynamic Wake Meandering model is based, can be utilized to include atmospheric stabi...

  10. A computational platform for physically-based bank evolution and long-term meander migration

    Science.gov (United States)

    RVR Meander is a simplified two-dimensional (2D) hydrodynamic and migration model (Abad and Garcia, 2006) while CONCEPTS (CONservational Channel Evolution and Pollutant Transport System) is a one-dimensional (1D) hydrodynamic and morphodynamic model (Langendoen and Alonso, 2008; Langendoen and Simon...

  11. Antenna-in-package system integrated with meander line antenna based on LTCC technology

    Institute of Scientific and Technical Information of China (English)

    Gang DONG; Wei XIONG; Zhao-yao WU; Yin-tang YANG

    2016-01-01

    We present an antenna-in-package system integrated with a meander line antenna based on low temperature co-fi red ceramic (LTCC) technology. The proposed system employs a meander line patch antenna, a packaging layer, and a laminated multi-chip module (MCM) for integration of integrated circuit (IC) bare chips. A microstrip feed line is used to reduce the interaction between patch and package. To decrease electromagnetic coupling, a via hole structure is designed and analyzed. The meander line antenna achieved a bandwidth of 220 MHz with the center frequency at 2.4 GHz, a maximum gain of 2.2 dB, and a radiation efficiency about 90% over its operational frequency. The whole system, with a small size of 20.2 mm×6.1 mm×2.6 mm, can be easily realized by a standard LTCC process. This antenna-in-package system integrated with a meander line antenna was fabricated and the experimental results agreed with simulations well.

  12. Bank retreat study of a meandering river reach case study: River Irwell

    NARCIS (Netherlands)

    Duran, R.; Beevers, L.; Crosato, A.; Wright, N.

    2010-01-01

    Lack of data is often considered a limitation when undertaking morphological studies. This research deals with morphological studies of small rivers experiencing bank erosion processes when only limited data are available. A reach of the meandering gravel-bed river Irwell (United Kingdom) is taken

  13. Fabrication of superconducting NbN meander nanowires by nano-imprint lithography

    Science.gov (United States)

    Mei, Yang; Li-Hua, Liu; Lu-Hui, Ning; Yi-Rong, Jin; Hui, Deng; Jie, Li; Yang, Li; Dong-Ning, Zheng

    2016-01-01

    Superconducting nanowire single photon detector (SNSPD), as a new type of superconducting single photon detector (SPD), has a broad application prospect in quantum communication and other fields. In order to prepare SNSPD with high performance, it is necessary to fabricate a large area of uniform meander nanowires, which is the core of the SNSPD. In this paper, we demonstrate a process of patterning ultra-thin NbN films into meander-type nanowires by using the nano-imprint technology. In this process, a combination of hot embossing nano-imprint lithography (HE-NIL) and ultraviolet nano-imprint lithography (UV-NIL) is used to transfer the meander nanowire structure from the NIL Si hard mold to the NbN film. We have successfully obtained a NbN nanowire device with uniform line width. The critical temperature (Tc) of the superconducting NbN meander nanowires is about 5 K and the critical current (Ic) is about 3.5 μA at 2.5 K. Project supported by the National Basic Research Program of China (Grant Nos. 2011CBA00106 and 2009CB929102) and the National Natural Science Foundation of China (Grant Nos. 11104333 and 10974243).

  14. Antenna-in-package system integrated with meander line antenna based on LTCC technology

    Institute of Scientific and Technical Information of China (English)

    Gang DONG; Wei XIONG; Zhao-yao WU; Yin-tang YANG

    2016-01-01

    We present an antenna-in-package system integrated with a meander line antenna based on low temperature co-fired ceramic (LTCC) technology. The proposed system employs a meander line patch antenna, a packaging layer, and a laminated multi-chip module (MCM) for integration of integrated circuit (IC) bare chips. A microstrip feed line is used to reduce the interaction between patch and package. To decrease electromagnetic coupling, a via hole structure is designed and analyzed. The meander line antenna achieved a bandwidth of 220 MHz with the center frequency at 2.4 GHz, a maximum gain of 2.2 dB, and a radiation efficiency about 90% over its operational frequency. The whole system, with a small size of 20.2 minx6.1 mmx2.6 mm, can be easily realized by a standard LTCC process. This antenna-in-package system integrated with a meander line antenna was fabricated and the experimental results agreed with simulations well.

  15. Controls on cutoff formation along a tropical meandering river in the Amazon Basin

    Science.gov (United States)

    Ahmed, J.; Constantine, J. A.

    2016-12-01

    The termination of meander bends is an inherent part of the evolution of meandering rivers. Cutoffs are produced by one of two mechanisms: neck cutoffs occur when two adjacent meanders converge, while chute cutoffs are generated by flood-driven floodplain incision, resulting in a shorter, steeper channel path. Here we use an annually-resolved record of Landsat imagery, coupled with daily discharge data to assess the role of high-magnitude discharges (Q ≥ QBF) on cutoff formation along the Rio Beni, Bolivia. Our results suggest that despite numerous above-bankfull events, the dominant cutoff mechanism operating on the Beni is neck cutoff. Evaluating the formation of these cutoffs reveals that migration rates accelerate during years of high discharge, and eventually cause the migrating bends to breach. The density of floodplain vegetation and the medium into which the channel migrated was also responsible for the patterns of cutoff documented along this river. The presence of existing floodplain channels permitted the river to divert its flow along shorter courses thereby facilitating cutoff, and limiting sinuosity growth. Understanding the long-term evolution of meandering channels is important since their morphodynamics are responsible for the creation of highly biodiverse riparian habitats, as well as the store and release of alluvial material. Moreover, the interactions between discharge and the channel-floodplain system are integral for the functioning and long-term evolution of these landscapes, particularly in the face of global climate change.

  16. Bank retreat study of a meandering river reach case study: River Irwell

    NARCIS (Netherlands)

    Duran, R.; Beevers, L.; Crosato, A.; Wright, N.

    2010-01-01

    Lack of data is often considered a limitation when undertaking morphological studies. This research deals with morphological studies of small rivers experiencing bank erosion processes when only limited data are available. A reach of the meandering gravel-bed river Irwell (United Kingdom) is taken

  17. A consistent turbulence formulation for the dynamic wake meandering model in the atmospheric boundary layer

    DEFF Research Database (Denmark)

    Keck, Rolf-Erik; Veldkamp, Dick; Wedel-Heinen, Jens Jakob

    This thesis describes the further development and validation of the dynamic meandering wake model for simulating the flow field and power production of wind farms operating in the atmospheric boundary layer (ABL). The overall objective of the conducted research is to improve the modelling capabil...... intensity. This power drop is comparable to measurements from the North Hoyle and OWEZ wind farms....

  18. Bifurcation instability and chute cutoff development in meandering gravel-bed rivers

    NARCIS (Netherlands)

    Van Dijk, Wout M.; Schuurman, Filip; Van de Lageweg, Wietse I.; Kleinhans, Maarten G.

    2014-01-01

    Chute cutoffs reduce sinuosity of meandering rivers and potentially cause a transition from a single to a multiple channel river. The channel bifurcation of the main channel and the mouth of the incipient chute channel controls sediment and flow partitioning and development of the chute. Recent chan

  19. Captures, Cutoffs, and Autogenic Drainage Basin Reorganization from Bedrock River Meandering in the Oregon Coast Range

    Science.gov (United States)

    Johnson, K. N.; Finnegan, N. J.

    2015-12-01

    Meandering bedrock channels in the Oregon Coast Range (OCR), USA, have lateral migration rates far in excess of vertical incision rates. Consequently, the sweeping of trunk streams through this landscape can locally exert a much stronger influence on tributary channel long profiles than far-field tectonic forcing of base-level. Here, we use LiDAR-data to explore the influence of lateral channel mobility on the evolution of tributaries to the Smith River, in the OCR. We focus on two processes that dramatically and instantaneously change tributary long profiles: 1) Capture of tributaries by growing meander bends, and 2) Meander bend neck cutoffs on the main-stem that leave tributaries disconnected from base-level lowering. We focus on these two types of events because they provide clear examples of autogenic drivers of landscape disequilibrium at the sub-watershed scale in a landscape that is commonly argued to reflect steady tectonic forcing of base-level. We show that tributary streams are significantly more likely to flow into the leading edge of meander bends, testifying to the repeated capture of tributaries by growing bends. Examples of eminent captures by migrating bends, and examples with large knick points along recently captured tributaries suggest that the autogenic capture of tributaries by growing bends is a fundamental cause of transience in tributary channels in this landscape. To demonstrate the influence of the process of meander bend neck cutoff on tributary long profile evolution, we compare the long profiles of 34 tributaries that were hung above the main-stem of the Smith River following neck cutoff events. These stagnated tributary channels typically exhibit large convexities that record ongoing lowering of the trunk stream. Measured heights of these hanging tributaries implies that the timescale of adjustment for tributaries following cutoff events is ~ 105-106 years. The timescale of adjustment of tributary channels following meander cutoff

  20. Integration of fluvial erosion factors for predicting landslides along meandering rivers

    Science.gov (United States)

    Chen, Yi-chin; Chang, Kang-tsung; Ho, Jui-yi

    2015-04-01

    River incision and lateral erosion are important geomorphologic processes in mountainous areas of Taiwan. During a typhoon or storm event, the increase of water discharge, flow velocity, and sediment discharge enhances the power of river erosion on channel bank. After the materials on toe of hillslope were removed by river erosion, landslides were triggered at outer meander bends. Although it has been long expected that river erosion can trigger landslide, studies quantifying the effects of river erosion on landslide and the application of river erosion index in landslide prediction are still overlooked. In this study, we investigated the effect of river erosion on landslide in a particular meanders landscape of the Jhoukou River, southern Taiwan. We developed a semi-automatic model to separate meandering lines into several reach segments based on the inflection points and to calculate river erosion indexes, e.g. sinuosity of meander, stream power, and stream order, for each reach segment. This model, then, built the spatial relationship between the reaches and its corresponding hillslopes, of which the toe was eroded by the reach. Based on the spatial relationship, we quantified the correlations between these indexes and landslides triggered by Typhoon Morakot in 2009 to examine the effects of river erosion on landslide. The correlated indexes were then used as landslide predictors in logistic regression model. Results of the study showed that there is no significant correlation between landslide density and meander sinuosity. This may be a result of wider channel dispersing the erosion at a meandering reach. On the other hand, landslide density at concave bank is significantly higher than that at convex bank in the downstream (stream order > 3), but that is almost the same in the upstream (stream order < 3). This may imply that river sediment play different roles between down- and upstream segments. River sediment in the upstream is an erosion agent vertically

  1. Wake meandering statistics of a model wind turbine: Insights gained by large eddy simulations

    Science.gov (United States)

    Foti, Daniel; Yang, Xiaolei; Guala, Michele; Sotiropoulos, Fotis

    2016-08-01

    Wind tunnel measurements in the wake of an axial flow miniature wind turbine provide evidence of large-scale motions characteristic of wake meandering [Howard et al., Phys. Fluids 27, 075103 (2015), 10.1063/1.4923334]. A numerical investigation of the wake, using immersed boundary large eddy simulations able to account for all geometrical details of the model wind turbine, is presented here to elucidate the three-dimensional structure of the wake and the mechanisms controlling near and far wake instabilities. Similar to the findings of Kang et al. [Kang et al., J. Fluid Mech. 744, 376 (2014), 10.1017/jfm.2014.82], an energetic coherent helical hub vortex is found to form behind the turbine nacelle, which expands radially outward downstream of the turbine and ultimately interacts with the turbine tip shear layer. Starting from the wake meandering filtering used by Howard et al., a three-dimensional spatiotemporal filtering process is developed to reconstruct a three-dimensional meandering profile in the wake of the turbine. The counterwinding hub vortex undergoes a spiral vortex breakdown and the rotational component of the hub vortex persists downstream, contributing to the rotational direction of the wake meandering. Statistical characteristics of the wake meandering profile, along with triple decomposition of the flow field separating the coherent and incoherent turbulent fluctuations, are used to delineate the near and far wake flow structures and their interactions. In the near wake, the nacelle leads to mostly incoherent turbulence, while in the far wake, turbulent coherent structures, especially the azimuthal velocity component, dominate the flow field.

  2. Determination of real-time predictors of the wind turbine wake meandering

    Science.gov (United States)

    Muller, Yann-Aël; Aubrun, Sandrine; Masson, Christian

    2015-03-01

    The present work proposes an experimental methodology to characterize the unsteady properties of a wind turbine wake, called meandering, and particularly its ability to follow the large-scale motions induced by large turbulent eddies contained in the approach flow. The measurements were made in an atmospheric boundary layer wind tunnel. The wind turbine model is based on the actuator disc concept. One part of the work has been dedicated to the development of a methodology for horizontal wake tracking by mean of a transverse hot wire rake, whose dynamic response is adequate for spectral analysis. Spectral coherence analysis shows that the horizontal position of the wake correlates well with the upstream transverse velocity, especially for wavelength larger than three times the diameter of the disc but less so for smaller scales. Therefore, it is concluded that the wake is actually a rather passive tracer of the large surrounding turbulent structures. The influence of the rotor size and downstream distance on the wake meandering is studied. The fluctuations of the lateral force and the yawing torque affecting the wind turbine model are also measured and correlated with the wake meandering. Two approach flow configurations are then tested: an undisturbed incoming flow (modelled atmospheric boundary layer) and a disturbed incoming flow, with a wind turbine model located upstream. Results showed that the meandering process is amplified by the presence of the upstream wake. It is shown that the coherence between the lateral force fluctuations and the horizontal wake position is significant up to length scales larger than twice the wind turbine model diameter. This leads to the conclusion that the lateral force is a better candidate than the upstream transverse velocity to predict in real time the meandering process, for either undisturbed (wake free) or disturbed incoming atmospheric flows.

  3. Influence of Large Woody Debris on Three-dimensional Flow Structure Through Meander Bends in a Low-energy Stream

    Science.gov (United States)

    Newell, M. D.; Rhoads, B. L.

    2001-05-01

    Most theoretical research on the dynamics of meandering streams has emphasized the importance of internal mechanisms. Although there is an abundance of empirical work on external factors, theoretical development in this area has been limited, especially for biotic factors, such as LWD, which geomorphologists have long recognized constitute important external mechanisms in fluvial systems. In particular, little is known about the role of LWD in low-energy, human-modified streams. One important potential morphological influence of LWD that has not been investigated is the potential for LWD to alter flow structures through meander bends, a critical element of current meander evolution theories since three dimensional characteristics of flow through meander bends have been shown to have a significant impact on the processes of sediment transport and bank erosion, and consequently meander development. The overall goal of this project is to advance the understanding of the interactions between large woody debris and the geomorphic structure and function of low-gradient meandering streams. This improved understanding will provide a more reliable framework of knowledge on which to base stream naturalization (i.e. the return to pre-disturbance conditions) and management plans for low-energy meandering streams with abundant LWD.

  4. A review of crustacean sensitivity to high amplitude underwater noise: Data needs for effective risk assessment in relation to UK commercial species.

    Science.gov (United States)

    Edmonds, Nathan J; Firmin, Christopher J; Goldsmith, Denise; Faulkner, Rebecca C; Wood, Daniel T

    2016-07-15

    High amplitude anthropogenic noise is associated with adverse impacts among a variety of organisms but detailed species-specific knowledge is lacking in relation to effects upon crustaceans. Brown crab (Cancer pagurus), European lobster (Homarus gammarus) and Norway lobster (Nephrops norvegicus) together represent the most valuable commercial fishery in the UK (Defra, 2014). Critical evaluation of literature reveals physiological sensitivity to underwater noise among N. norvegicus and closely related crustacean species, including juvenile stages. Current evidence supports physiological sensitivity to local, particle motion effects of sound production in particular. Derivation of correlative relationships between the introduction of high amplitude impulsive noise and crustacean distribution/abundance is hindered by the coarse resolution of available data at the present time. Future priorities for research are identified and argument for enhanced monitoring under current legislative frameworks outlined. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  5. MEANDER-LINE CURRENT STRUCTURE DEVELOPMENT FOR SPALLATION NEUTRON SOURCE FAST CHOPPER

    Energy Technology Data Exchange (ETDEWEB)

    S. KURRENOY; J. POWER

    2000-10-01

    A new current structure for the fast traveling-wave 2.5-MeV beam chopper in the front end of the Spallation Neutron Source (SNS) has been suggested in [1]. The structure is based on the meander-folded notched stripline with dielectric supports and separators. Its design has been optimized using electromagnetic 3-D modeling with the MAFIA code package to provide rise and fall times in the range of 1 to 2 ns. A full-length (50 cm) prototype has been manufactured, and its preliminary measurements showed a good agreement with the calculations. Detailed measurements results and their comparison with simulations are presented. The latest front-end design requires a shorter, 35-cm chopper with a higher pulse voltage. Its meander-line current structure, based on the same principles, has also been optimized with MAFIA.

  6. Simulation of Helical Flow Hydrodynamics in Meanders and Advection-Turbulent Diffusion Using Smoothed Particle Hydrodynamics

    Science.gov (United States)

    Gusti, T. P.; Hertanti, D. R.; Bahsan, E.; Soeryantono, H.

    2013-12-01

    Particle-based numerical methods, such as Smoothed Particle Hydrodynamics (SPH), may be able to simulate some hydrodynamic and morphodynamic behaviors better than grid-based numerical methods. This study simulates hydrodynamics in meanders and advection and turbulent diffusion in straight river channels using Microsoft Excel and Visual Basic. The simulators generate three-dimensional data for hydrodynamics and one-dimensional data for advection-turbulent diffusion. Fluid at rest, sloshing, and helical flow are simulated in the river meanders. Spill loading and step loading are done to simulate concentration patterns associated with advection-turbulent diffusion. Results indicate that helical flow is formed due to disturbance in morphology and particle velocity in the stream and the number of particles does not have a significant effect on the pattern of advection-turbulent diffusion concentration.

  7. Chute Formation and Iterative Adjustment in Large, Sand-Bed Meandering Rivers

    Science.gov (United States)

    Grenfell, M. C.; Aalto, R. E.; Nicholas, A.

    2011-12-01

    The meandering-braided continuum is a planform manifestation of excess available river energy; a balance between the energy of flow (commonly quantified as unit steam power or shear stress), and dynamic resistance due to bed material calibre and bank strength. Single-thread meandering rivers plot in part of the continuum defined by low excess available river energy, while braided rivers plot in part of the continuum defined by high excess available river energy. Planform patterns that are transitional between single-thread meandering and braided occur where chute channel formation is prolific. In this presentation we will elucidate the morphodynamic implications of chute formation for sinuosity and planform pattern in large, sand-bed meandering rivers. We draw on the results of recent research that applied binary logistic regression analysis to determine the possibility of predicting chute initiation based on attributes of meander bend character and dynamics (Grenfell et al., accepted, ESP&L). Regression models developed for the Strickland River, Papua New Guinea (54 bends), the lower Paraguay River, Paraguay/Argentina (45 bends), and the Beni River, Bolivia (114 bends), revealed that the probability of chute initiation at a meander bend is a function of the bend extension rate (the rate at which a bend elongates). Image analyses of all rivers and field observations from the Strickland suggest that the majority of chute channels form during scroll-slough development. Rapid extension is shown to favour chute initiation by breaking the continuity of point bar deposition and vegetation encroachment at the inner bank, resulting in widely-spaced scrolls with intervening sloughs that are positively aligned with primary over-bar flow. The rivers plot in order of increasing chute activity on an empirical meandering-braided pattern continuum (Kleinhans and van den Berg, 2011, ESP&L 36) defined by potential specific stream power (ωpv) and bedload calibre (D50). Increasing

  8. The linkage between fluvial meander-belt morphodynamics and the depositional record improves paleoenvironmental interpretations, Western Interior Basin, Alberta, Canada

    Science.gov (United States)

    Durkin, P.; Hubbard, S. M.

    2016-12-01

    Enhanced stratigraphic interpretations are possible when linkages between morphodynamic processes and the depositional record are resolved. Recent studies of modern and ancient meander-belt deposits have emphasized morphodynamic processes that are commonly understated in the analysis of stratigraphic products, such as intra-point bar erosion and rotation, counter-point-bar (concave bank-bench) development and meander-bend abandonment. On a larger scale, longitudinal changes in meander-belt morphology and processes such as changes in meander-bend migration rate, channel-belt width/depth ratio and sinuosity have been observed as rivers flow through the tidal backwater zone. However, few studies have attempted to recognize the impact of the backwater zone in the stratigraphic record. We consider ancient meander-belt deposits of the Cretaceous McMurray Formation and document linkages between morphodynamic processes and their stratigraphic product to resolve more detailed paleoenvironmental interpretations. The ancient meander belt was characterized by paleochannels that were 600 m wide and up to 50 m deep, resolved in a particularly high quality subsurface dataset consisting of 600 km2 of high-quality 3-D seismic data and over 1000 wellbores. A 3-D geocellular model and reconstructed paleochannel migration patterns reveal the evolutionary history of seventeen individual meander belt elements, including point bars, counter point bars and their associated abandoned channel fills. At the meander-bend scale, intra-point-bar erosion surfaces bound accretion packages characterized by unique accretion directions, internal stratigraphic architecture and lithologic properties. Erosion surfaces and punctuated bar rotation are linked to upstream changes in channel planform geometry (meander cut-offs). We provide evidence for downstream translation and development of counter-point bars that formed in response to valley-edge and intra-meander-belt confinement. At the meander

  9. Compact rat-race ring coupler with meander high-impedance transmission line and port impedance matching

    Directory of Open Access Journals (Sweden)

    Jun He

    2015-08-01

    Full Text Available A novel compact rat-race ring coupler with meander high-impedance transmission line and port impedance matching is presented in this Letter. First, a ring coupler with high port impedance is designed using meander lines. Secondly, an impedance matching section is designed to match the high port impedance to ordinary 50 Ω. The proposed coupler effectively reduces occupied area to 16.8% of conventional one. The design is validated both by simulation and measurement.

  10. Geodiversity of a large meander bend in the Little Belt strait in the inner Danish waters

    Science.gov (United States)

    Brandbyge Ernstsen, Verner; Øbro Hansen, Lars; Becker, Marius; Brivio, Lara; Vang, Torben; Lynnerup Trinhammer, Per; Andresen, Katrine Juul; Seidenkrantz, Marit-Solveig; Boldreel, Lars Ole; Bartholdy, Jesper

    2017-04-01

    The Little Belt strait in the inner Danish waters is characterised by a high biodiversity, and continuous monitoring of flora and fauna and the water quality is undertaken by the authorities. However, the surface sedimentology and geomorphology, i.e. elements of the geodiversity, are less well-constrained. The aim of this study is to investigate the surface sediment and morphology of a large meander bend (with a channel width of 1 km) located between the two bridges crossing the strait (a channel reach of 4 km) in order to assess a potential coupling between geodiversity and biodiversity. More specifically, the objectives are 1) to identify and classify morphological units for creating a geomorphological map, 2) to quantify surface material characteristics for creating a surface material map, and 3) to develop a conceptual model of the substrate and the morphology and morphodynamics in the meander bend between the two bridges in the strait. Preliminary results reveal a diverse morphology in the meander bend; and the annual morphological changes reveal complex sediment transport patterns along and across the bend. Likewise significant sediment sorting trends exist along and across the meander bend. Hence, the preliminary results indicate a high geodiversity in the strait. Acknowledgements The data were collected as part of the MSc course Marine Geoscience, a joint MSc course between the Department of Geosciences and Natural Resource Management at the University of Copenhagen and the Department of Geoscience at Aarhus University. Additional data were included from the research project Control in the Danish Straits 1 (CiDS-1) funded by the Danish Centre for Marine Research (PI Morten Holtegaard). Thanks to the crew on board RV Aurora.

  11. On the relevance of diapycnal mixing for the stability of frontal meanders

    Directory of Open Access Journals (Sweden)

    A. Rodríguez-Santana

    2001-07-01

    Full Text Available This work examines the possible importance of shear-induced diapycnal mixing in controlling the evolution and stability of meanders in oceanic frontal jets. We first review the conditions necessary for vortex stability and investigate how these may be modified in the presence of diapycnal mixing. The procedure used is rather crude but provides a measure of the relative importance of diapycnal mixing. It consists in constructing a simplified equation for the radial velocity that retains the density tendency and examining under what circumstances this velocity may grow in time. Next, we use a simple two-dimensional isopycnic model to examine the intensity of diapycnal mixing in meanders. In the model the along-front velocity is in geostrophic balance and the ageostrophic contributions are an oscillating deformation field and diapycnal mass exchange. The horizontal deformation field increases the slope of the isopycnals in temporal scales typical of Gulf Stream meanders, causing a reduction of the gradient Richardson number, Ri. The diapycnal flux is calculated as the divergence of the density Reynolds flux, which is parameterized in terms of Ri. The results of the model show that diapycnal mixing increases during the frontogenetical stages, reaching density tendency values of the order of 10-4 kg m-3s-1 and convergence/divergence values of the order of 10-3 s-1. It turns out that diapycnal mixing in meanders may be intense enough to control the separation and slope of the isopycnals and to condition the possibility of barotropic instability.

  12. The effect of floodplain grass on the flow characteristics of meandering compound channels

    Science.gov (United States)

    Liu, Chao; Shan, Yuqi; Liu, Xingnian; Yang, Kejun; Liao, Huasheng

    2016-11-01

    Laboratory experiments were conducted in a large-scale meandering compound channel to investigate the effect of floodplain grass on the main flow field in the channel. Three-dimensional velocity fields, turbulences, and Reynolds shear stresses were measured along half a meander. The experiments revealed that flexible artificial grass planted on a floodplain can significantly reduce the conveyance capability of the entire channel. Two parallel stage-discharge curves increased with increasing flow depth. The additional resistance of the floodplain grass increased the streamwise velocity and conveyance in the main channel along a meander. An analysis of the generation mechanism of secondary flows in the main channel indicated that the secondary current consisted of an enhanced original secondary cell that was strengthened by the centrifugal force and a component of the upstream floodplain flow. The relative dominance of these two components in the secondary flows was primarily determined by the angle between the floodplain flow and the main channel ridge, and also the floodplain roughness. At the same flow depth, the secondary flow in cases with grass on the floodplain was generally stronger than that in the case of a smooth meander bend, although it was weaker near the middle cross-over section. Floodplain grass enhanced the intensity of the lateral turbulence above the bankfull level and significantly modified the turbulence structure, although it had a negligible effect on the vertical turbulence except at the bend entrance. Floodplain grass also affected the Reynolds shear stresses in the main channel, generating stronger lateral shear stresses at a low flow depth. In contrast, at a high flow depth, the distribution of the interface shear stresses changed entirely while its magnitude remained the same. When the floodplains were grassed, the vertical shear stress that was induced by secondary flows was greater at the apexes but reduced at the cross-over sections

  13. Development of a modular MR valve using meandering flow path structure

    Science.gov (United States)

    Ichwan, B.; Mazlan, S. A.; Imaduddin, F.; Ubaidillah; Koga, T.; Idris, M. H.

    2016-03-01

    The extensive development of the magnetorheological (MR) valve has successfully introduced a new high-performance compact-class MR valve using a meandering flow path structure. Aside from the performance improvement, in real applications, the ease of performance adjustment also needs to be improved. This study focused on the development of a new design of a modular MR valve using a meandering flow path to improve the adjustability of the valve performance. The approach is proposed based on the high-performance advantages of a meandering flow path structure, while at the same time utilizing the benefit of the modular structure in terms of performance flexibility. In order to evaluate the performance of the modular structure, the analytical assessment was conducted for three different module stages: the single-stage module, the double-stage module, and triple-stage module. To predict the strength of the magnetic field in the effective area, the magnetic simulation was conducted through an open-source software called the FEMM (Finite Element Method Magnetics). The quasi-steady mathematical model of the proposed valve was also derived to conduct the analytical assessment as well as to predict the valve performance. In order to validate the simulation results, the prototypes of the proposed valve are experimentally tested with the aid of the hydraulic cylinder on a dynamic test machine. The results of the MR valve assessment from both the simulation and experimental test demonstrated that the pressure drop rating of the meandering type MR valve can be easily modified using modular structure by changing the number of module stages.

  14. Scroll wave meandering induced by phase difference in a three-dimensional excitable medium.

    Science.gov (United States)

    Yang, Zhao; Gao, Shiyuan; Ouyang, Qi; Wang, Hongli

    2012-11-01

    We investigated scroll waves in an inhomogeneous excitable 3D system with gradient of excitability. The gradient promotes twisting of the scroll waves. Sufficiently large excitability gradient enhances the twisting and causes simple scroll waves to transition to meandering scroll waves. For the twist-induced instability of scroll waves, we analyzed the stability of 2D spiral waves sliced from the twisted scroll in the vertical direction. The 3D problem is simplified by taking into account the diffusive coupling in the third direction as a time-delayed perturbation to the 2D spiral wave. An additional "negative mass" term measuring the twist thus arises in the 2D system and induces the transition from simple rotation to meandering. A further increase in the gradient ruins partially the unity of the meandering scrolls and generates semiturbulence, the analogs of which were observed in the Belousov-Zhabotinski reaction. We also generated the phase diagram in the parameter space by adjusting the threshold for excitation of the media.

  15. Meandering instability of air flow in a granular bed: self-similarity and fluid-solid duality

    Science.gov (United States)

    Yoshimura, Yuki; Yagisawa, Yui; Okumura, Ko

    2016-12-01

    Meandering instability is familiar to everyone through river meandering or small rivulets of rain flowing down a windshield. However, its physical understanding is still premature, although it could inspire researchers in various fields, such as nonlinear science, fluid mechanics and geophysics, to resolve their long-standing problems. Here, we perform a small-scale experiment in which air flow is created in a thin granular bed to successfully find a meandering regime, together with other remarkable fluidized regimes, such as a turbulent regime. We discover that phase diagrams of the flow regimes for different types of grains can be universally presented as functions of the flow rate and the granular-bed thickness when the two quantities are properly renormalized. We further reveal that the meandering shapes are self-similar as was shown for meandering rivers. The experimental findings are explained by theory, with elucidating the physics. The theory is based on force balance, a minimum-dissipation principle, and a linear-instability analysis of a continuum equation that takes into account the fluid-solid duality, i.e., the existence of fluidized and solidified regions of grains along the meandering path. The present results provide fruitful links to related issues in various fields, including fluidized bed reactors in industry.

  16. Passionflower Extract Induces High-amplitude Rhythms without Phase Shifts in the Expression of Several Circadian Clock Genes in Vitro and in Vivo.

    Science.gov (United States)

    Toda, Kazuya; Hitoe, Shoketsu; Takeda, Shogo; Shimizu, Norihito; Shimoda, Hiroshi

    2017-06-01

    Circadian rhythms play key roles in the regulation of physiological and behavioral systems including wake-sleep cycles. We evaluated the effects of passionflower (aerial parts of Passiflora incarnata Linnaeus) extract (PFE) on circadian rhythms using NIH3T3 cells and mice. PFE (100 μg/mL) induced high-amplitude rhythms in the expression of period circadian protein (Per) 2, cryptochrome (Cry) 1, superoxide dismutase (SOD) 1, and glutathione peroxidase (GPx) in vitro from 12 h after a treatment with serum-rich medium. Isovitexin 2"-O-glucoside, isoschaftoside, and homoorientin, which were purified from PFE, also significantly enhanced Per2 mRNA expression at 20 h. An oral treatment with PFE (100 mg/kg/day) at zeitgeber time (ZT) 0 h for 15 days improved sleep latencies and sleeping times in the pentobarbital-induced sleep test in mice, similar to muscimol (0.2 mg/kg, i.p.). PFE induced high-amplitude rhythms without obvious phase shifts in serum corticosterone levels and the expression of Per1, Per2, and Cry1 in the liver as well as NIH3T3 cells. However, in the cerebrum, PFE enhanced the circadian expression of brain-muscle ARNT-like protein (Bmal) 1, circadian locomotor output cycles kaput (Clock), and Per1. Regarding this difference, we suggest the involvement of several neurotransmitters that influence the circadian rhythm. Indeed, PFE significantly increased dopamine levels at ZT 18 h, and then affected the mRNA expression of the synthetic and metabolic enzymes such as monoamine oxidase (MAO), catechol-O-methyltransferase (COMT), and glutamic acid decarboxylase (GAD). The results obtained show that PFE positively modulates circadian rhythms by inducing high-amplitude rhythms in the expression of several circadian clock genes.

  17. A consistent turbulence formulation for the dynamic wake meandering model in the atmospheric boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Keck, R.-E.

    2013-07-15

    This thesis describes the further development and validation of the dynamic meandering wake model for simulating the flow field and power production of wind farms operating in the atmospheric boundary layer (ABL). The overall objective of the conducted research is to improve the modelling capability of the dynamics wake meandering model to a level where it is sufficiently mature to be applied in industrial applications and for an augmentation of the IEC-standard for wind turbine wake modelling. Based on a comparison of capabilities of the dynamic wake meandering model to the requirement of the wind industry, four areas were identified as high prioritizations for further research: 1. the turbulence distribution in a single wake. 2. multiple wake deficits and build-up of turbulence over a row of turbines. 3. the effect of the atmospheric boundary layer on wake turbulence and wake deficit evolution. 4. atmospheric stability effects on wake deficit evolution and meandering. The conducted research is to a large extent based on detailed wake investigations and reference data generated through computational fluid dynamics simulations, where the wind turbine rotor has been represented by an actuator line model. As a consequence, part of the research also targets the performance of the actuator line model when generating wind turbine wakes in the atmospheric boundary layer. Highlights of the conducted research: 1. A description is given for using the dynamic wake meandering model as a standalone flow-solver for the velocity and turbulence distribution, and power production in a wind farm. The performance of the standalone implementation is validated against field data, higher-order computational fluid dynamics models, as well as the most common engineering wake models in the wind industry. 2. The EllipSys3D actuator line model, including the synthetic methods used to model atmospheric boundary layer shear and turbulence, is verified for modelling the evolution of wind

  18. Spatial variability in bank resistance to erosion on a large meandering, mixed bedrock-alluvial river

    Science.gov (United States)

    Konsoer, Kory M.; Rhoads, Bruce L.; Langendoen, Eddy J.; Best, James L.; Ursic, Mick E.; Abad, Jorge D.; Garcia, Marcelo H.

    2016-01-01

    Spatial heterogeneity in the erosion-resistance properties of the channel banks and floodplains associated with sediment characteristics, vegetation, or bedrock can have a substantial influence on the morphodynamics of meandering rivers, resulting in highly variable rates of bank erosion and complex patterns of planform evolution. Although past studies have examined the spatial variability in bank erodibility within small rivers, this aspect of the erosion-resistance properties for large rivers remains poorly understood. Furthermore, with the exception of recent numerical modeling that incorporates stochastic variability of floodplain erosional resistance, most models of meandering river dynamics have assumed uniform erodibility of the bank and floodplain materials. The present paper investigates the lateral and vertical heterogeneity in bank material properties and riparian vegetation within two elongate meander loops on a large mixed bedrock-alluvial river using several geotechnical field and laboratory methods. Additionally, the bank stability and toe-erosion numerical model (BSTEM) and repeat terrestrial LiDAR surveys are used to evaluate the capacity of the bank material properties to modify the rates and mechanisms of bank retreat. Results show that the textural properties of the bank materials, soil cohesion, and critical shear stress necessary for sediment entrainment differ substantially between the two bends and are also highly variable within each bend - laterally and vertically. Trees growing along the banks increase the resistance to erosion by contributing to the shear strength of the bank materials and are capable of increasing bank stability along a large river. Locally outcropping bedrock also influences bank erodibility in both bends. The results of this study demonstrate that spatial variability in the erosion-resistance properties of the channel banks is an important factor contributing to spatial variability in the rates and mechanisms of bank

  19. RIVER BED TOPOGRAPHY IN MEANDERING STREAMS AND ITS RELATIONSHIP WITH LOCAL SCOUR

    Directory of Open Access Journals (Sweden)

    Mahmud GÜNGÖR

    2006-01-01

    Full Text Available In Meandering Streams, deformation in bed topography occurs due to secondary flows. This situation significantly increases the local scour depths around hydraulic structures such as bridge piers and dikes, especially at the central angles of ~60º, ~130º and outer boundaries of the channel. Therefore, it is important to determine bed topography in dealing with local scour depths around hydraulic structures and investigate its effect on scour depths. In this study, bed deformations generated before the construction of hydraulic structure in a channel bend of 180o due to only flow are investigated. For this purpose, a series of experiments were made and bed topography was obtained by measuring the bed elevations at each central angle of 5o. As a result of the experimantal study, scour was not much observed in the beginning of the meander because the meterials coming from the upstream replaces the carried material, but it was observed that the scour depth increases because of the lack of incoming material. The generated relative flow depths were determined at flow axis and along the line which was thought to be at a distance of 20 % of channel width from the channel boundary and bed topography generated by the effect of flow was obtained. As a result, it was observed that the parameters which are effective in the generation of bed topography due to flow at meandering channel have the same effect in the generation of local scour when an obstacle is placed and that the bed topography and local scour depths have a very close similarity.

  20. Three Dimensional Large Eddy Simulation Model of Turbulence in a Meandering Channel

    Science.gov (United States)

    Akahori, R.; Schmeeckle, M. W.

    2002-12-01

    Recent research has shown that intermittency caused by large-scale turbulence structures in rivers can be critical to accurate prediction of the sediment transport field. These large-scale turbulence structures are inherently three-dimensional. This is especially true in a river meander where strong secondary flows affect not only the three-dimensional, time-averaged flow structure, but also the process of large-scale turbulent eddy generation. It is very difficult to directly measure the turbulence field in a river except at the water surface or a few points in the interior of the flow. Numerical simulation of turbulence is a powerful tool, because it can provide information about the non-averaged flow at each grid point. Many previous researchers have calculated the time-averaged flow in a meandering channel, and obtained useful results. However, simulations of turbulence in meandering channels have been restricted to two dimensions. Therefore, they have a problem in accurately reproducing important features of the flow. We present a 3-dimenstional turbulent model for the numerical calculation of channel flow. The turbulence cannot be resolved at scales smaller than the channel grid, and we therefore parameterize the effects of small scale turbulence using standard Large Eddy Simulation (LES) assumptions. A Body Fitted Coordinate (BFC) system is employed to fit the irregular boundaries of natural channels. To solve the Navier-Stokes equations on the finite difference mesh, we employ the Cubic-Interpolated Propagation (CIP) method. The CIP method precisely solves the convective acceleration terms without numerical diffusion.

  1. Non linear bend instability theory and finite amplitude evolution of bed deformations in meandering rivers

    Science.gov (United States)

    Bolla Pittaluga, M.; Nobile, G.; Seminara, G.

    2007-12-01

    We develop a three dimensional non linear asymptotic theory for flow and bed topography in meandering channels able to describe finite amplitude perturbations of bottom topography. The model extends a previous analysis on the equilibrium finite bed deformations, accounting here for arbitrary, yet slow, variations of channel curvature. This approach then allows us to formulate a non-linear bend instability theory, which predicts several characteristic features of the actual meandering process and extends results obtained by classical linear bend theories. In agreement with previous weakly non linear findings and consistently with field observations, the bend growth rate turns out to have a peak at some value of the meander wavenumber, typically larger than the resonant value of linear stability theory. Moreover, a feature typical of non linear waves arises: the selected wavenumber depends on the amplitude of the initial perturbation and, in particular, larger wavelengths are associated with larger amplitudes. The picture offered by results obtained through the present theory seems fully satisfactory and consistent with field observations as well as previous theoretical findings. Further substantiation of the model has been achieved by comparing predictions obtained for a test case (a reach of the Cecina river, Italy) with field observations. Finally the model is also extended to follow the evolution of bed deformations in time in order to investigate the morphological response of the river to a sequence of flood events characterized by a slow temporal variation of flow and sediment supply. Such an investigation would possibly provide a rational interpretation of the as yet loosely defined notion of formative discharge of an alluvial river.

  2. Spatiotemporal variations in channel changes caused by cumulative factors in a meandering river: The lower Peixe River, Brazil

    Science.gov (United States)

    Morais, Eduardo S.; Rocha, Paulo C.; Hooke, Janet

    2016-11-01

    Channel changes in meandering rivers naturally exhibit complex behaviour, and understanding the river dynamics can be challenging in environments also subject to cumulative human impacts. Planform changes were analysed on four reaches of the lower course of the Peixe River, Brazil, at decadal scales over the period 1962-2008 from aerial photographs and satellite imagery, complemented by a historical map from 1907. Analysis of the spatial and temporal patterns of channel change mechanisms and morphometry of bends and of the sinuosity and morphodynamic variations of the reaches demonstrates major changes in planform characteristics. Sinuosity in all reaches decreased from 2.6 to 1.7, average wavelength of bends has increased from 200 to 500 m, and the planform has become much simpler. Changes have been progressive from downstream to upstream, with higher intensities of processes, particularly cutoffs first in downstream reaches then more recently in upstream reaches. It is suggested that channel changes represent a morphological adjustment to human interventions, such as reservoir construction and land use. However, evidence of the autogenic behaviour of meanders is highlighted in which the existence of compound meanders reveals control over the spatial variation in the reaches. The results suggest that geomorphic thresholds associated with the compound meander formation and the bend evolution should be considered, even in impacted meandering rivers, because they exert primary controls on the spatial-temporal adjustment of channels.

  3. Fluvial Processes in the Meandering Reach of the Lower Wei River During the Course of Degradation

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This paper presents an analysis of the changes of the longitudinal and lateral profiles in the meander- ing reach of the Lower Wei River over the period from October 1973 to October 1976 during the course of degradation.Analysis results indicated that retrogressive erosion and subsequent downstream erosion occurred in the reach due to the lowering in the Tongguan elevation and the inflowing water carrying low sediment con- centrations.At the end of the degradation,the main channel widths of the majority ...

  4. Using High-Resolution Field Measurements to Model Dune Kinematics in a Large Elongate Meander Bend.

    Science.gov (United States)

    Konsoer, K. M.; Rhoads, B. L.; Best, J.; Frias, C. E.; Abad, J. D.; Langendoen, E. J.

    2014-12-01

    Due to recent advances in hydroacoustic technology, such as the development of multibeam echo sounders, it is now possible to obtain highly accurate and detailed bathymetric data for river channels. These data provide the basis for detailed characterizations of bed form morphology ranging from individual ripples to composite dune fields. Theoretical models suggest that bed forms reach an equilibrium morphology based on hydraulic conditions during steady flow. However, at the scale of individual meander bends, bed form morphology will vary according to the local flow structure as influenced by overall bed morphology and planform curvature. Thus, the coevolution of flow structure, bed form morphology, and sediment transport should vary throughout a meander bend. This paper examines spatial variation in bed form characteristics and rates of bed form migration, and thus bed material transport, within a large, actively migrating, elongate meander loop. During a May 2013 flood event on Maier Bend, Wabash River (IL-IN, USA), repeat multibeam echo sounding surveys were conducted ~4 hours apart, providing estimates of dune celerity and volumetric rates of sediment transport at different locations around the bend. Three-dimensional velocity measurements, obtained using an acoustic Doppler current profiler, provide hydraulic data for evaluating interactions between flow structure and bed form morphology. Results show that bed form morphology is highly variable within the bend, ranging from barchans dunes on the upstream limb, 2D ripples across the point bar, and 3D composite dunes with wavelength of ~20 meters near the bend apex. Rates of dune celerity varied from 0.3 m/hr to 0.7 m/hr and were dependent on bed form geometry and local hydraulic conditions. The high-resolution data on flow and form are used to calibrate a 2D numerical model of sediment transport through the bend. Simulations using the calibrated model are used to evaluate the fluvial processes underlying

  5. An inkjet printed meandered dipole antenna for RF passive sensing applications

    KAUST Repository

    Quddious, Abdul

    2016-04-10

    In this paper, a low cost inkjet printed antenna envisioned for integration with printed and non-printed RF sensors is presented. The proposed meandered dipole dual-loop antenna is designed on a 0.25mm thick paper substrate. The antenna not only gives wireless remote sensing capability but also allows remote identification functionality. The antenna structure consists of an outer loop and an inner loop resonating at 3GHz and 5GHz respectively and used for obtaining unique electromagnetic signature by modifications in their dimensions.

  6. Breakup of shearless meanders and ``outer'' tori in the standard nontwist map

    Science.gov (United States)

    Fuchss, K.; Wurm, A.; Apte, A.; Morrison, P. J.

    2006-09-01

    The breakup of shearless invariant tori with winding number ω =(11+γ)/(12+γ) (in continued fraction representation) of the standard nontwist map is studied numerically using Greene's residue criterion. Tori of this winding number can assume the shape of meanders [folded-over invariant tori which are not graphs over the x axis in (x,y) phase space], whose breakup is the first point of focus here. Secondly, multiple shearless orbits of this winding number can exist, leading to a new type of breakup scenario. Results are discussed within the framework of the renormalization group for area-preserving maps. Regularity of the critical tori is also investigated.

  7. Design and simulation of MEMS vector hydrophone with reduced cross section based meander beams

    Science.gov (United States)

    Kumar, Manoj; Dutta, S.; Pal, Ramjay; Jain, K. K.; Gupta, Sudha; Bhan, R. K.

    2016-04-01

    MEMS based vector hydrophone is being one of the key device in the underwater communications. In this paper, we presented a bio-inspired MEMS vector hydrophone. The hydrophone structure consists of a proof mass suspended by four meander type beams with reduced cross-section. Modal patterns of the structure were studied. First three modal frequencies of the hydrophone structure were found to be 420 Hz, 420 Hz and 1646 Hz respectively. The deflection and stress of the hydrophone is found have linear behavior in the 1 µPa - 1Pa pressure range.

  8. A Miniaturize Bandpass Filter with Harmonic Suppression Using Meandered Quarter-Wavelength Resonators

    Directory of Open Access Journals (Sweden)

    Yun-Long Lu

    2014-01-01

    Full Text Available A miniaturized bandpass filter with harmonics suppression is presented. The proposed filter consists of two quarter-wavelength microstrip resonators, which are meandered for circuit size reduction. An interdigital capacitor, loading at zero-voltage point, is employed to provide the desired coupling between the resonators at operating frequency, whereas the coupling coefficient at the third harmonic is realized to be zero. Besides, the second and fourth harmonics are suppressed since λ/4 resonators are adopted. Benefiting from these properties, a miniaturized bandpass filter with the second, third, and fourth harmonics suppression was designed and implemented. The final measured and simulated results show good consistence with the theoretical counterparts.

  9. Numerical Simulation of Sediment Movement and Deposition in a Meandering Channel

    Directory of Open Access Journals (Sweden)

    Usman Ghani

    2011-10-01

    Full Text Available In this research work, predictions have been made for the transport and deposition of incoming sediments in an open channel. Attempt has been made to understand the behavior of sediments flowing in the channel. The geometry consisted of a meandering compound channel with a constant inflow of sediments. For this purpose, 3D version of CFD (Computational Fluid Dynamics code FLUENT has been used as a research tool. The turbulence closure of Reynolds Averaged Navior-Stokes equation was performed with standard - turbulence model. The Lagrangian particle tracking technique available in the code has been used for modeling sediment movement and deposition. For this purpose, nine different ranges of the particle diameters were released at the inlet of the channel. Initially, the model was validated using point velocities in the downstream direction and discharge values at five cross sections along the meander wavelength. The channel used for simulation purposes had a rectangular section. Once the model validated, it was then used for simulation of sediments. The numerical modeling gave a detailed picture of sediment deposited and transported through the channel. As the model was used with - turbulence model and Lagrangian particle tracking technique and then validated, it showed that when this combination of particle tracking and turbulence closure option will be used, the prediction will be fairly good and trustworthy. A number of numerical experiments were conducted to get the impact of sediment inflow velocity and its diameter on deposition patterns. It showed that boundary shearing stresses and secondary flows had considerable impact on sediment deposition in a river bend. The current study revealed that CFD technique can be used for predicting sediment distribution patterns with reasonable confidence. Such prediction techniques are not only economical but also provide details of complex flow and sediment movement behavior which are difficult to get

  10. Modelling and fabrication of a compliant centrally supported meandering piezoelectric energy harvester using screenprinting technology

    Science.gov (United States)

    Fernandes, E.; Zarabi, S.; Debéda, H.; Lucat, C.; Nairn, D.; Wei, L.; Salehian, A.

    2016-11-01

    This paper reports the design, simulation, fabrication, and experimental testing of a low-frequency piezoelectric energy harvester fabricated using screen-printing technology. A centrally supported meandering geometry is chosen to reduce the torsional mode effects during the unit vibrations and to achieve better power efficiency. The design experiences alternating stress along the beams and a strain-matching polarization technique is used to minimize voltage cancellation. The test results are validated against the finite element solution for which there is a good agreement.

  11. Search for high-amplitude Delta Scuti and RR Lyrae stars in Sloan Digital Sky Survey Stripe 82 using principal component analysis

    CERN Document Server

    Süveges, M; Váradi, M; Mowlavi, N; Becker, A C; Ivezić, Ž; Beck, M; Nienartowicz, K; Rimoldini, L; Dubath, P; Bartholdi, P; Eyer, L

    2012-01-01

    We propose a robust principal component analysis (PCA) framework for the exploitation of multi-band photometric measurements in large surveys. Period search results are improved using the time series of the first principal component due to its optimized signal-to-noise ratio.The presence of correlated excess variations in the multivariate time series enables the detection of weaker variability. Furthermore, the direction of the largest variance differs for certain types of variable stars. This can be used as an efficient attribute for classification. The application of the method to a subsample of Sloan Digital Sky Survey Stripe 82 data yielded 132 high-amplitude Delta Scuti variables. We found also 129 new RR Lyrae variables, complementary to the catalogue of Sesar et al., 2010, extending the halo area mapped by Stripe 82 RR Lyrae stars towards the Galactic bulge. The sample comprises also 25 multiperiodic or Blazhko RR Lyrae stars.

  12. Numerical Simulation on Seismic Response of the Filled Joint under High Amplitude Stress Waves Using Finite-Discrete Element Method (FDEM

    Directory of Open Access Journals (Sweden)

    Xiaolin Huang

    2016-12-01

    Full Text Available This paper numerically investigates the seismic response of the filled joint under high amplitude stress waves using the combined finite-discrete element method (FDEM. A thin layer of independent polygonal particles are used to simulate the joint fillings. Each particle is meshed using the Delaunay triangulation scheme and can be crushed when the load exceeds its strength. The propagation of the 1D longitude wave through a single filled joint is studied, considering the influences of the joint thickness and the characteristics of the incident wave, such as the amplitude and frequency. The results show that the filled particles under high amplitude stress waves mainly experience three deformation stages: (i initial compaction stage; (ii crushing stage; and (iii crushing and compaction stage. In the initial compaction stage and crushing and compaction stage, compaction dominates the mechanical behavior of the joint, and the particle area distribution curve varies little. In these stages, the transmission coefficient increases with the increase of the amplitude, i.e., peak particle velocity (PPV, of the incident wave. On the other hand, in the crushing stage, particle crushing plays the dominant role. The particle size distribution curve changes abruptly with the PPV due to the fragments created by the crushing process. This process consumes part of wave energy and reduces the stiffness of the filled joint. The transmission coefficient decreases with increasing PPV in this stage because of the increased amount of energy consumed by crushing. Moreover, with the increase of the frequency of the incident wave, the transmission coefficient decreases and fewer particles can be crushed. Under the same incident wave, the transmission coefficient decreases when the filled thickness increases and the filled particles become more difficult to be crushed.

  13. Testing the role of meander cutoff in promoting gene flow across a riverine barrier in ground skinks (Scincella lateralis.

    Directory of Open Access Journals (Sweden)

    Nathan D Jackson

    Full Text Available Despite considerable attention, the long-term impact of rivers on species diversification remains uncertain. Meander loop cutoff (MLC is one river phenomenon that may compromise a river's diversifying effects by passively transferring organisms from one side of the river to the other. However, the ability of MLC to promote gene flow across rivers has not been demonstrated empirically. Here, we test several predictions of MLC-mediated gene flow in populations of North American ground skinks (Scincella lateralis separated by a well-established riverine barrier, the Mississippi River: 1 individuals collected from within meander cutoffs should be more closely related to individuals across the river than on the same side, 2 individuals within meander cutoffs should contain more immigrants than individuals away from meander cutoffs, 3 immigration rates estimated across the river should be highest in the direction of the cutoff event, and 4 the distribution of alleles native to one side of the river should be better predicted by the historical rather than current path of the river. To test these predictions we sampled 13 microsatellite loci and mitochondrial DNA from ground skinks collected near three ancient meander loops. These predictions were generally supported by genetic data, although support was stronger for mtDNA than for microsatellite data. Partial support for genetic divergence of samples within ancient meander loops also provides evidence for the MLC hypothesis. Although a role for MLC-mediated gene flow was supported here for ground skinks, the transient nature of river channels and morphologies may limit the long-term importance of MLC in stemming population divergence across major rivers.

  14. Statistical meandering wake model and its application to yaw-angle optimisation of wind farms

    Science.gov (United States)

    Thøgersen, E.; Tranberg, B.; Herp, J.; Greiner, M.

    2017-05-01

    The wake produced by a wind turbine is dynamically meandering and of rather narrow nature. Only when looking at large time averages, the wake appears to be static and rather broad, and is then well described by simple engineering models like the Jensen wake model (JWM). We generalise the latter deterministic models to a statistical meandering wake model (SMWM), where a random directional deflection is assigned to a narrow wake in such a way that on average it resembles a broad Jensen wake. In a second step, the model is further generalised to wind-farm level, where the deflections of the multiple wakes are treated as independently and identically distributed random variables. When carefully calibrated to the Nysted wind farm, the ensemble average of the statistical model produces the same wind-direction dependence of the power efficiency as obtained from the standard Jensen model. Upon using the JWM to perform a yaw-angle optimisation of wind-farm power output, we find an optimisation gain of 6.7% for the Nysted wind farm when compared to zero yaw angles and averaged over all wind directions. When applying the obtained JWM-based optimised yaw angles to the SMWM, the ensemble-averaged gain is calculated to be 7.5%. This outcome indicates the possible operational robustness of an optimised yaw control for real-life wind farms.

  15. Sediment Transport Dynamic in a Meandering Fluvial System: Case Study of Chini River

    Science.gov (United States)

    Nazir, M. H. M.; Awang, S.; Shaaban, A. J.; Yahaya, N. K. E. M.; Jusoh, A. M.; Arumugam, M. A. R. M. A.; Ghani, A. A.

    2016-07-01

    Sedimentation in river reduces the flood carrying capacity which lead to the increasing of inundation area in the river basin. Basic sediment transport can predict the fluvial processes in natural rivers and stream through modeling approaches. However, the sediment transport dynamic in a small meandering and low-lying fluvial system is considered scarce in Malaysia. The aim of this study was to analyze the current riverbed erosion and sedimentation scenarios along the Chini River, Pekan, Pahang. The present study revealed that silt and clay has potentially been eroded several parts of the river. Sinuosity index (1.98) indicates that Chini River is very unstable and continuous erosion process in waterways has increase the riverbank instability due to the meandering factors. The riverbed erosional and depositional process in the Chini River is a sluggish process since the lake reduces the flow velocity and causes the deposited particles into the silt and clay soil at the bed of the lake. Besides, the bed layer of the lake comprised of cohesive silt and clayey composition that tend to attach the larger grain size of sediment. The present study estimated the total sediment accumulated along the Chini River is 1.72 ton. The HEC-RAS was employed in the simulations and in general the model performed well, once all parameters were set within their effective ranges.

  16. Observations on the propagation, growth, and predictability of Gulf Stream meanders

    Science.gov (United States)

    Vazquez, J.; Watts, D. R.

    1985-01-01

    During a three-year period, Gulf Stream positions determined by satellite infrared imagery on a grid northeast of Cape Hatteras have been correlated against 'inlet' path parameters (displacement from the mean position, angle, and curvature) monitored by an array of inverted echo sounders. By cross-spectral calculations between these measurements, the downstream coherences, phase speeds, and spatial growth rates were determined. The downstream path predictability from these inlet parameters was tested in a multiple input linear response model. The most energetic meanders, with periods of 33-50 days, remained highly coherent for 300 km downstream, roughly the dominant wavelength, with marginal coherence again at 500-575 km. Phase speeds are frequency dependent and decrease with distance downstream. For the 50- (33) day meanders, phase speeds decreased from 10 (17) km/d at the inlet to 6 (8) km/d at a distance downstream of about 550 km. The average growth rate (spatial e-folding wave number) over the entire region is 1.3 x 10 to the -3rd per km. Within 300 km of the inlet, the multiple coherence accounts for 55-65 percent of the total path-displacement variance, with displacement and angle being the best individual predictors in the first and last halves of this region, respectively.

  17. Bandwidth enhancement of a dual band planar monopole antenna using meandered microstrip feeding.

    Science.gov (United States)

    Ahsan, M R; Islam, M T; Habib Ullah, M; Misran, N

    2014-01-01

    A meandered-microstrip fed circular shaped monopole antenna loaded with vertical slots on a high dielectric material substrate (ε r = 15) is proposed in this paper. The performance criteria of the proposed antenna have been experimentally verified by fabricating a printed prototype. The experimental results show that the proposed antenna has achieved wider bandwidth with satisfactory gain by introducing meandered-microstrip feeding in assistant of partial ground plane. It is observed that, the -10 dB impedance bandwidth of the proposed antenna at lower band is 44.4% (600 MHz-1 GHz) and at upper band is 28% (2.25 GHz-2.95 GHz). The measured maximum gains of -1.18 dBi and 4.87 dBi with maximum radiation efficiencies have been observed at lower band and upper band, respectively. The antenna configuration and parametric study have been carried out with the help of commercially available computer-aided EM simulator, and a good accordance is perceived in between the simulated and measured results. The analysis of performance criteria and almost consistent radiation pattern make the proposed antenna a suitable candidate for UHF RFID, WiMAX, and WLAN applications.

  18. Meandered Monopoles for 700 MHz LTE Handsets and Improved MIMO Channel Capacity Performance

    Directory of Open Access Journals (Sweden)

    I. Dioum

    2011-12-01

    Full Text Available In this paper, we present the design and the measurement of MIMO meandered monopole antennas and the computation of their channel capacity performance. The initial proposed handset-system is composed of a meandered monopole operating in the LTE 700 MHz band, connected to a parasitic radiating element for the upper 2.5 GHz LTE band. Two antennas of the same kind are then closely positioned on the same 120x50 mm2 Printed Circuit Board (PCB. A neutralization line connects the two antennas to enhance their port-to-port isolation in the 700 MHz band. The computation of the channel capacity performance in this band is based on propagation simulations performed with the GRIMM model from the CREMANT. Two system-prototypes are evaluated: one with the neutralization line for enhanced port-to-port isolation and a second without the neutralization exhibiting poor antenna-to-antenna isolation. It is demonstrated that the neutralization technique helps in giving a minimum improvement of 12% of the capacity performance of the handset-system, and a maximum improvement 46%, in the chosen environment.

  19. Measuring Plume Meander in the Nighttime Stable Boundary Layer with Lidar

    Science.gov (United States)

    Hiscox, A.; Miller, D. R.; Nappo, C. J.

    2009-12-01

    Complex dynamics of the stable planetary boundary layer (PBL), such as the effects of density currents, intermittent turbulence, surface-layer decoupling, internal gravity waves, cold air pooling, and katabatic flows affect plume transport and diffusion. A better understanding of these effects is needed for nighttime transport model development. The JORNADA (Joint Observational Research on Nocturnal Atmospheric Dispersion of Aerosols) field campaign, conducted in the New Mexico desert during April 2005, sought to address some of these issues The JORNADA data set includes simultaneous micrometeorological measurements of the boundary layer structure, turbulence, and wave activity along with continuous lidar measurement of aerosol plume releases. What makes JORNADA unique is the real-time monitoring of an elevated plume with a lidar. The quantification of plume meander will be presented in this paper. The application of these techniques to the JORNADA data allows for a more complete understanding of the nocturnal boundary layer (NBL). We will present an in-depth analysis of lidar measurements of plume meander and dispersion and their relationship to the complexities of NBL structure.

  20. High-amplitude, centennial-scale climate oscillations during the last glacial in the western Third Pole as recorded in the Guliya ice cap

    Science.gov (United States)

    Thompson, L. G.; Yao, T.; Mosley-Thompson, E.; Wu, G.; Davis, M. E.; Tian, L.; Lin, P. N.

    2015-12-01

    The Guliya ice cap, located in the Kunlun Mountains in the western Third Pole (TP) region near the northern limit of the southwest monsoon influence, may be the only non-polar ice field that provides detailed histories of climate and environment over the last glacial cycle. A continuous climate record from an ice core drilled in 1992 contains Eemian ice, and basal temperatures measured that year confirmed that the record was not being removed from the bottom. The δ18O record throughout Marine Isotope Stage 2 (MIS2) displays the occurrence of high-amplitude (~20‰) episodes of ~200-year periodicity, and the aerosol records suggest snow cover, regional vegetation and fire frequency that vary in synchrony. These oscillations might reflect the movement of the northernmost penetration of the monsoon precipitation through the Late Glacial Stage, which is restricted by the topographic barrier posed by the Kunlun range, and might also reflect solar-driven nonlinearities in the climate system such as sudden shifts in the jet stream. Recent model simulations suggest that glacial cooling over China was significantly amplified by stationary waves, and the Guliya MIS2 oscillations could reflect cyclical variability in these waves. These results are supported by clumped isotope thermometry of carbonates from the Chinese Loess Plateau, which indicate a 6 to 7oC decrease in Last Glacial Maximum summer temperatures. These studies will lead to a better understanding of the mechanisms driving such high-frequency, high-amplitude oscillations. A review of the 2015 Sino-American cooperative ice core drilling program on Guliya is presented. This program will serve as a flagship for the TP Environment Program, an international, multidisciplinary collaboration among professionals and students in 14 countries designed to investigate environmental changes across the TP. The rapidly warming TP contains ~46,000 glaciers that collectively hold one of Earth's largest stores of fresh water that

  1. A 3D forward stratigraphic model of fluvial meander-bend evolution for prediction of point-bar lithofacies architecture

    Science.gov (United States)

    Yan, Na; Mountney, Nigel P.; Colombera, Luca; Dorrell, Robert M.

    2017-08-01

    Although fundamental types of fluvial meander-bend transformations - expansion, translation, rotation, and combinations thereof - are widely recognised, the relationship between the migratory behaviour of a meander bend, and its resultant accumulated sedimentary architecture and lithofacies distribution remains relatively poorly understood. Three-dimensional data from both currently active fluvial systems and from ancient preserved successions known from outcrop and subsurface settings are limited. To tackle this problem, a 3D numerical forward stratigraphic model - the Point-Bar Sedimentary Architecture Numerical Deduction (PB-SAND) - has been devised as a tool for the reconstruction and prediction of the complex spatio-temporal migratory evolution of fluvial meanders, their generated bar forms and the associated lithofacies distributions that accumulate as heterogeneous fluvial successions. PB-SAND uses a dominantly geometric modelling approach supplemented by process-based and stochastic model components, and is constrained by quantified sedimentological data derived from modern point bars or ancient successions that represent suitable analogues. The model predicts the internal architecture and geometry of fluvial point-bar elements in three dimensions. The model is applied to predict the sedimentary lithofacies architecture of ancient preserved point-bar and counter-point-bar deposits of the middle Jurassic Scalby Formation (North Yorkshire, UK) to demonstrate the predictive capabilities of PB-SAND in modelling 3D architectures of different types of meander-bend transformations. PB-SAND serves as a practical tool with which to predict heterogeneity in subsurface hydrocarbon reservoirs and water aquifers.

  2. Reply to ‘‘Comments on ‘On the Steadiness of Separating Meandering Currents’’’

    NARCIS (Netherlands)

    van Leeuwen, P.J.; de Ruijter, W.P.M.

    2012-01-01

    The authors thank Nof et al. for their comments on the authors’ paper ‘‘On the steadiness of separating meandering currents.’’ The authors’ paper was motivated by a series of papers by Nof et al. Under a certain set of conditions (reduced gravity, steady state, no meridional velocity at outflow, and

  3. Validation of the dynamic wake meander model with focus on tower loads

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Larsen, Gunner Chr.; Pedersen, Mads Mølgaard

    2017-01-01

    of wind speeds. In general, tower loads in wake conditions are very challenging to predict correctly in simulations. The Nysted project offers an improved insight to this field as six wind turbines located in the Nysted II wind farm have been instrumented to measure tower top and tower bottom moments. All...... a period extending over a time span of more than 3 years. Based on the recorded data basic mechanisms driving the increased loading experienced by wind turbines operating in offshore wind farm conditions have been identified, characterized and modeled. The modeling is based on the Dynamic Wake Meandering...... (DWM) approach in combination with the state-of-the-art aeroelastic model HAWC2, and has previously as well as in this study shown good agreement with the measurements. The conclusions from the study have several parts. In general the tower bending and yaw loads show a good agreement between...

  4. Design of a Miniaturized Meandered Line Antenna for UHF RFID Tags

    Science.gov (United States)

    Islam, Mohammad Tariqul; Rowe, Wayne S. T.; Kibria, Salehin; Jit Singh, Mandeep; Misran, Norbahiah

    2016-01-01

    A semi-circle looped vertically omnidirectional radiation (VOR) patterned tag antenna for UHF (919–923 MHz for Malaysia) frequency is designed to overcome the impedance mismatch issue in this paper. Two impedance matching feeding strips are used in the antenna structure to tune the input impedance of the antenna. Two dipole shaped meandered lines are used to achieve a VOR pattern. The proposed antenna is designed for 23-j224 Ω chip impedance. The antenna is suitable for ‘place and tag’ application. A small size of 77.68×35.5 mm2 is achieved for a read range performance of 8.3 meters using Malaysia regulated maximum power transfer of 2.0 W effective radiated power (ERP). PMID:27533470

  5. Lateral Dispersion of Pollutants in a Very Stable Atmosphere - The Effect of Meandering

    DEFF Research Database (Denmark)

    Kristensen, Leif; Jensen, Niels Otto; Lundtang Petersen, Erik

    1981-01-01

    A model based on single particle diffusion is introduced to account for the effect of “meandering” on lateral plume dispersion in a very stable atmosphere. It is assumed that small scale atmospheric turbulence is absent, so that only large horizontal eddies are effective. A formula for the lateral...... standard deviation σy as function of observation time, distance from source, mean wind speed, lateral turbulence intensity, and scale of the atmospheric motion is derived. Climatological time series of temperature lapse rates, wind speeds, and wind directions can be used as input to calculate σy....... Meteorological data from Risø and the small island Sprogø have been analysed in order to identify all situations in which the atmosphere is so stable that small scale turbulence cannot exist. The purpose is to see in how many of these situations meandering is also absent. The results show that, as a rule...

  6. A Compact Dual Band Implantable Antenna Based on Split-Ring Resonators with Meander Line Elements

    Directory of Open Access Journals (Sweden)

    Yunus Emre Yamac

    2016-12-01

    Full Text Available In this paper, a dual band implantable split-ring microstrip antenna which operates at MICS (Medical Implant Services and ISM (Industrial, Scientific, and Medical bands is proposed for biotelemetry applications. A miniaturized size of 9.5 mm × 9.5 mm × 1.27 mm was accomplished by using three split-ring resonators and meander lines elements on these resonators. A shorting pin appropriately placed between the patch and ground plane was used for the antenna miniaturization. In addition, three useful metallic paths between the rings provided fine frequency tuning. The proposed split-ring implantable antenna presents 23.5% and 9.3% bandwidth, -48 dB and -24 dB maximum gains, 407 W/kg and 403 W/kg maximum 1-g averaged SAR values at the respective bands. Return loss performance, radiation patterns and SAR values of the antenna design are presented in the paper.

  7. Great expectations - Epigenetics and the meandering path from bench to bedside

    DEFF Research Database (Denmark)

    Häfner, Sophia J; Lund, Anders H

    2016-01-01

    Making quick promises of major biomedical breakthroughs based on exciting discoveries at the bench is tempting. But the meandering path from fundamental science to life-saving clinical applications can be fraught with many hurdles. Epigenetics, the study of potentially heritable changes of gene...... a conceptual framework to a mechanistic understanding. This shift was accompanied by much hype and raised high hopes that epigenetics might hold both the key to deciphering the molecular underpinning of complex, non-Mendelian diseases and offer novel therapeutic approaches for a large panel of pathologies....... However, while exciting reports of biological phenomena involving DNA methylation and histone modifications fill up the scientific literature, the realistic clinical applications of epigenetic medicines remain somewhat blurry. Here, we discuss the state of the art and speculate how epigenetics might...

  8. Development of silicon microforce sensors integrated with double meander springs for standard hardness test instruments

    Science.gov (United States)

    Wasisto, Hutomo Suryo; Doering, Lutz; Daus, Alwin; Brand, Uwe; Frank, Thomas; Peiner, Erwin

    2015-05-01

    Silicon microforce sensors, to be used as a transferable standard for micro force and depth scale calibrations of hardness testing instruments, are developed using silicon bulk micromachining technologies. Instead of wet chemical etching, inductively coupled plasma (ICP) cryogenic deep reactive ion etching (DRIE) is employed in the sensor fabrication process leading to more precise control of 300 μm deep structures with smooth sidewall profiles. Double meander springs are designed flanking to the boss replacing the conventional rectangular springs and thereby improving the system linearity. Two full p-SOI piezoresistive Wheatstone bridges are added on both clamped ends of the active sensors. To realize passive force sensors two spring-mass elements are stacked using glue and photoresist as joining materials. Correspondingly, although plastic deformation seems to occur when the second spring is contacted, the kink effect (i.e., abrupt increase of stiffness) is obviously observed from the first test of the passive stack sensor.

  9. Estimation of annual energy production using dynamic wake meandering in combination with ambient CFD solutions

    Science.gov (United States)

    Hahn, S.; Machefaux, E.; Hristov, Y. V.; Albano, M.; Threadgill, R.

    2016-09-01

    In the present study, combination of the standalone dynamic wake meandering (DWM) model with Reynolds-averaged Navier-Stokes (RANS) CFD solutions for ambient ABL flows is introduced, and its predictive performance for annual energy production (AEP) is evaluated against Vestas’ SCADA data for six operating wind farms over semi-complex terrains under neutral conditions. The performances of conventional linear and quadratic wake superposition techniques are also compared, together with the in-house implemention of successive hierarchical merging approaches. As compared to our standard procedure based on the Jensen model in WindPRO, the overall results are promising, leading to a significant improvement in AEP accuracy for four of the six sites. While the conventional linear superposition shows the best performance for the improved four sites, the hierarchical square superposition shows the least deteriorated result for the other two sites.

  10. Implementation of a Mixing Length Turbulence Formulation Into the Dynamic Wake Meandering Model

    DEFF Research Database (Denmark)

    Keck, Rolf-Erik; Veldkamp, Dick; Aagaard Madsen, Helge

    2012-01-01

    The work presented in this paper focuses on improving the description of wake evolution due to turbulent mixing in the dynamic wake meandering (DWM) model. From wake investigations performed with high-fidelity actuator line simulations carried out in ELLIPSYS3D, it is seen that the current DWM...... description, where the eddy viscosity is assumed to be constant in each cross-section of the wake, is insufficient. Instead, a two-dimensional eddy viscosity formulation is proposed to model the shear layer generated turbulence in the wake, based on the classical mixing length model. The performance...... from 3 to 12 diameters behind the rotor, is reduced by 27% by using the new eddy viscosity formulation. ©2012 American Society of Mechanical Engineers...

  11. A 94 GHz CMOS based oscillator transmitter with an on-chip meandered dipole antenna

    KAUST Repository

    Cheema, Hammad M.

    2015-10-26

    A miniaturized 94 GHz oscillator transmitter in 65nm CMOS is presented. An extremely small silicon foot-print of 0.25mm2 is achieved through meandering of the top-metal dipole antenna, conjugate matching between the oscillator and the antenna without impedance matching elements and efficient placement of the oscillator circuit within the antenna. The antenna demonstrates bandwidth of 90 to 99 GHz (10%) and a gain of -6dBi. The use of parasitic aware antenna-circuit code-sign strategy results in an accurate measured oscillation frequency of 94.1 GHz. The oscillator exhibits a measured output power of -25 dBm, phase noise of -88 dBc/Hz at 1 MHz offset and consumes 8.4mW from a 1V supply. © 2015 IEEE.

  12. InGaAs/GaAs (110) quantum dot formation via step meandering

    Energy Technology Data Exchange (ETDEWEB)

    Diez-Merino, Laura; Tejedor, Paloma [Department of Nanostructures and Surfaces, Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Ines de la Cruz 3, 28049-Madrid (Spain)

    2011-07-01

    InGaAs (110) semiconductor quantum dots (QDs) offer very promising prospects as a material base for a new generation of high-speed spintronic devices, such as single electron transistors for quantum computing. However, the spontaneous formation of InGaAs QDs is prevented by two-dimensional (2D) layer-by-layer growth on singular GaAs (110) substrates. In this work we have studied, by using atomic force microscopy and photoluminescence spectroscopy (PL), the growth of InGaAs/GaAs QDs on GaAs (110) stepped substrates by molecular beam epitaxy (MBE), and the modification of the adatom incorporation kinetics to surface steps in the presence of chemisorbed atomic hydrogen. The as-grown QDs exhibit lateral dimensions below 100 nm and emission peaks in the 1.35-1.37 eV range. It has been found that a step meandering instability derived from the preferential attachment of In adatoms to [110]-step edges relative to [11n]-type steps plays a key role in the destabilization of 2D growth that leads to 3D mound formation on both conventional and H-terminated vicinal substrates. In the latter case, the driving force for 3D growth via step meandering is enhanced by H-induced upward mass transport in addition to the lower energy cost associated with island formation on H-terminated substrates, which results in a high density array of InGaAs/GaAs dots selectively nucleated on the terrace apices with reduced lateral dimensions and improved PL efficiency relative to those of conventional MBE-grown samples.

  13. Seismic Sedimentology Interpretation Method of Meandering Fluvial Reservoir:From Model to Real Data

    Institute of Scientific and Technical Information of China (English)

    Tao Zhang; Xianguo Zhang; Chengyan Lin; Jingfeng Yu; Shouxiu Zhang

    2015-01-01

    Reservoir architecture of meandering river deposition is complex and traditional seismic facies interpretation method cannot characterize it when layer thickness is under seismic vertical reso-lution. In this study, a seismic sedimentology interpretation method and workflow for point bar char-acterization is built. Firstly, the influences of seismic frequency and sandstone thickness on seismic re-flection are analyzed by outcrop detection with ground penetrating radar (GPR) and seismic forward modeling. It is found that (1) sandstone thickness can influence seismic reflection of point bar architec-ture. With the increasing of sandstone thickness from 1/4 wavelength (λ) to λ/2, seismic reflection ge-ometries various from ambiguous reflection,“V”type reflection to“X”type reflection;(2) seismic fre-quency can influence reservoirs’ seismic reflection geometry. Seismic events follow inclined lateral ag-gradation surfaces, which is isochronic depositional boundaries, in high frequency seismic data while the events extend along lithologic surfaces, which are level, in low frequency data. Secondly, strata slice interpretation method for thin layer depositional characterization is discussed with seismic forward modeling. Lastly, a method and workflow based on the above study is built which includes seismic fre-quency analysis, 90º phasing, stratal slicing and integrated interpretation of slice and seismic profile. This method is used in real data study in Tiger shoal, the Gulf of Mexico. Two episodes of meandering fluvial deposition is recognized in the study layer. Sandstone of the lower unit, which is formed in low base level stage, distributes limited. Sandstone distribution dimension and channel sinuosity become larger in the upper layer, which is high base level deposition.

  14. Influence of riparian vegetation on near-bank flow structure and erosion rates on a large meandering river

    Science.gov (United States)

    Konsoer, K. M.; Rhoads, B. L.; Langendoen, E. J.; Johnson, K.; Ursic, M.

    2012-12-01

    Rates of meander migration are dependent upon dynamic interactions between planform geometry, three-dimensional flow structure, sediment transport, and the erodibility and geotechnical properties of the channel banks and floodplains. Riparian vegetation can greatly reduce the rate of migration through root-reinforcement and increased flow resistance near the bank. In particular, forested riverbanks can also provide large woody debris (LWD) to the channel, and if located near the outer bank, can act to amour the bank by disrupting three-dimensional flow patterns and redirecting flow away from the bank-toe, the locus of erosion in meandering rivers. In this paper, three-dimensional flow patterns and migration rates are compared for two meander bends, one forested and one non-forested, on the Wabash River, near Grayville, Illinois. Flow data were obtained using acoustic Doppler current profilers (ADCP) for two large flow events in May and June 2011. LWD was mapped using a terrestrial LiDAR survey, and residence times for the LWD were estimated by comparing the survey data to time-series aerial photography. Rates of migration and planform evolution were determined through time-series analysis of aerial photography from 1938-2011. Results from this study show that near-bank LWD can have a significant influence on flow patterns through a meander bend and can disrupt helical flow near the outer bank, thereby reducing the effect of the high velocity core on the toe of the bank. Additionally, these effects influence migration rates and the planform evolution of meandering rivers.

  15. A 3-D numerical model of the influence of meanders on groundwater discharge to a gaining stream in an unconfined sandy aquifer

    Science.gov (United States)

    Balbarini, Nicola; Boon, Wietse M.; Nicolajsen, Ellen; Nordbotten, Jan M.; Bjerg, Poul L.; Binning, Philip J.

    2017-09-01

    Groundwater discharge to streams depends on stream morphology and groundwater flow direction, but are not always well understood. Here a 3-D groundwater flow model is employed to investigate the impact of meandering stream geometries on groundwater discharge to streams in an unconfined and homogenous sandy aquifer at the reach scale (10-200 m). The effect of meander geometry was examined by considering three scenarios with varying stream sinuosity. The interaction with regional groundwater flow was examined for each scenario by considering three groundwater flow directions. The sensitivity of stream morphology and flow direction to other parameters was quantified by varying the stream width, the meander amplitude, the magnitude of the hydraulic gradient, the hydraulic conductivity, and the aquifer thickness. Implications for a real stream were then investigated by simulating groundwater flow to a stream at a field site located in Grindsted, Denmark. The simulation of multiple scenarios was made possible by the employment of a computationally efficient coordinate transform numerical method. Comparison of the scenarios showed that the geometry of meanders greatly affect the spatial distribution of groundwater flow to streams. The shallow part of the aquifer discharges to the outward pointing meanders, while deeper groundwater flows beneath the stream and enters from the opposite side. The balance between these two types of flow depends on the aquifer thickness and meander geometry. Regional groundwater flow can combine with the effect of stream meanders and can either enhance or smooth the effect of a meander bend, depending on the regional flow direction. Results from the Grindsted site model showed that real meander geometries had similar effects to those observed for the simpler sinuous streams, and showed that despite large temporal variations in stream discharge, the spatial pattern of flow is almost constant in time for a gaining stream.

  16. Validation of the dynamic wake meander model for loads and power production in the Egmond aan Zee wind farm

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Aagaard Madsen, Helge; Larsen, Gunner Chr.;

    2013-01-01

    This paper investigates wake effects on load and power production by using the dynamic wake meander (DWM) model implemented in the aeroelastic code HAWC2. The instationary wind farm flow characteristics are modeled by treating the wind turbine wakes as passive tracers transported downstream using...... fatigue and min–mean–max loads for blade root flap, tower yaw and tower bottom bending moments, respectively. Since the observed turbine is located deep inside a row of turbines, a new method on how to handle multiple wakes interaction is proposed. The agreement between measurements and simulations...... is excellent regarding power production in both free and wake sector, and a very good agreement is seen for the load comparisons too. This enables the conclusion that wake meandering, caused by large scale ambient turbulence, is indeed an important contribution to wake loading in wind farms. Copyright © 2012...

  17. Ultrafast Linear Kinetic Inductive Photoresponse of YBa2Cu3O7-{\\delta} Meander-Line Structures by Photoimpedance Measurements

    CERN Document Server

    Atikian, Haig A; Anlage, Steven M; Majedi, A Hamed

    2010-01-01

    We report the experimental demonstration of linear kinetic-inductive photoresponse of thin-film YBa2Cu3O7-{\\delta} (YBCO) meander-line structures, where the photoresponse amplitude, full-width-half-maximum (FWHM), and rise-time are bilinear in the incident optical power and bias current. This bilinear behavior reveals a trade off between obtaining high responsivity and high speed photodetection. We also report a rise-time as short as 29ps in our photoimpedance measurements.

  18. Finite-element simulation of the performance of a superconducting meander structure shielding for a cryogenic current comparator

    Science.gov (United States)

    De Gersem, H.; Marsic, N.; Müller, W. F. O.; Kurian, F.; Sieber, T.; Schwickert, M.

    2016-12-01

    The ferrite core and measuring coil of a cryogenic current comparator have to be shielded against external magnetic fields by a compact, efficient meander structure made of superconducting niobium. A design with minimized material and production costs is only feasible when a highly accurate magnetic field simulator is available. 3D field models become prohibitively large. The cylindrical symmetry of the devices motivates to develop a quasi-3D field solver, exploiting the symmetry while still capable of representing 3D field distributions.

  19. Giant magnetoimpedance effect in a thin-film multilayer meander-like sensor

    Science.gov (United States)

    Vilela, G. L. S.; Monsalve, J. G.; Rodrigues, A. R.; Azevedo, A.; Machado, F. L. A.

    2017-03-01

    A meander-like magnetic sensing element based on the giant magnetoimpedance (GMI) effect was prepared by using optical lithography and sputtering deposition techniques. The structure of the sensing element consists of layers of Permalloy (Py = Ni81Fe19), titanium (Ti), and copper (Cu) with composition [Py(100 nm)/Ti(6 nm)]4/Cu(400 nm)/[Py(100 nm)/Ti(6 nm)]4. The GMI was investigated at room temperature under applied magnetic fields (H) varying in the range of ±4.0 kOe in both longitudinal and transversal geometries. The amplitude Iac and frequency f of the ac electrical current were varied in the range of 0.35-6.50 mA and 0.1-20 MHz, respectively. The overall dc electrical resistance of the sensing element was found to be 45.6 Ω. The sensing element yielded a GMI of 53.5% for H ≃ 5.0 Oe and f = 7.0 MHz, and the corresponding maximum average sensitivity of about 5 Ω/Oe. The sensing element was used for measuring the local Earth magnetic field ( H l o c a l = 0.26 ± 0.03 Oe) yielding a value close to the one measured by using a Hall sensor probe ( = 0.23 ± 0.01 Oe). GMI sensors are being used in applications such as accelerometers, magnetometers, biomagnetism, magnetic compasses, traffic control, non-destructive analysis, and virus and cancer cell detection.

  20. Hydrological controls on the morphogenesis of low-energy meanders (Cher River, France)

    Science.gov (United States)

    Dépret, Thomas; Gautier, Emmanuèle; Hooke, Janet; Grancher, Delphine; Virmoux, Clément; Brunstein, Daniel

    2015-12-01

    River restoration is a key-issue for European hydrosystems that were modified over centuries by human activities. This is particularly true for numerous low energy rivers flowing in the plateaus of Western Europe. Because of this limited energy, their potential in terms of autogenic restoration a priori appears strongly restricted. This study examines the conditions under which the morphogenesis on one of these systems occurs in relation to various hydrologic conditions. Two complementary approaches are combined on three reaches of the meandering Cher River (France). Firstly, we examine at a pluri-decadal scale the control of duration, frequency and intensity of floods on the planimetric erosion (bank retreat mainly). Secondly, we estimate the range of effective discharge for bedload transport. The results show that the morphogenesis is controlled by low magnitude hydrological events. Two major controlling factors are suggested: low differential of energy between small and large floods, peculiar to low energy rivers of mid-latitude, and low critical discharges for lateral erosion and bedload mobilization. For these reasons, the ability of the alluvial Cher River to self-restore its fluvial dynamics seems to be relatively high.

  1. Quasi 3D refined simulation of flow and pollutant transport in a meandering River Reach

    Directory of Open Access Journals (Sweden)

    Li-ren Yu

    2013-03-01

    Full Text Available This paper reports a quasi 3D numerical simulation in a meandering river reach of the Yellow River, aiming to develop a tool for modeling turbulent flows and pollutant transport in complex natural waters. The recently built depth-averaged two-equation turbulence model, together with and models, were used to close non-simplified quasi 3D hydrodynamic fundamental governing equations. The discretized equations were solved by advanced multi-grid iterative method under non-orthogonal body-fitted coarse and fine two-levels’ grids with collocated variable arrangement. Except for steady flow and transport computation, the processes of contaminant inpouring and plume development, caused by the side-discharge from a tribytary, also have been investigated numerically. The used three closure approaches are suitable for modeling strong mixing turbulence. The established model with higher order of magnitude of transported variable provides a possibility to elevate the computational precision. Based on the developed mathematical model, a CFD (Computational Fluid Dynamics software, namely Q3drm1.0, was developed. This numerical tool focuses on the refined simulations of the steady and unsteady problems of flow and temperature/contaminant transports in complicated computational domains with the strong ability to deal with different discharge situations: side-discharge, point-source discharge/point-sink, and area-source discharge from the slope along bank. In this article, the study of side-discharge is presented only.

  2. Miniaturized Meander Slot Antenna Tor RFID TAG with Dielectric Resonator at 60 Ghz

    Directory of Open Access Journals (Sweden)

    JMAL Sabri

    2016-04-01

    Full Text Available Day after day, recent advances in millimeter wave communications have called for the development of compact and efficient antennas. Furthermore, the greatest challenges in this area is to get a good performance and a miniaturized antenna. In addition, the design of antenna, in the Silicon technology, is one of the key challenges. In this way, this work will focus on the design of the free 60 GHz band, high gain and high efficiency on-chip antenna meandering slots for transponder Radio Frequency Identification (RFID. Further, the stacked dielectric resonators (DRS will be arranged above the power element of on-chip antenna with an excitation of coplanar waveguide (CPW. We will use the Scattering Bond-Graph formalism like a new technique to design these proposed antennas and we will use the microwave Studio CST software simulation to validate the results. We have miniaturized the proposed antenna after having such a number of iteration and by applying the Bond Graph methodology, and the size of the antenna is about 1.2 * 1.1 mm2.

  3. Great expectations - Epigenetics and the meandering path from bench to bedside.

    Science.gov (United States)

    Häfner, Sophia J; Lund, Anders H

    2016-06-01

    Making quick promises of major biomedical breakthroughs based on exciting discoveries at the bench is tempting. But the meandering path from fundamental science to life-saving clinical applications can be fraught with many hurdles. Epigenetics, the study of potentially heritable changes of gene function without modification of the underlying DNA sequence, has dominated the biological research field during the last decade and encountered a large public success. Driven by the unfolding of molecular biology and recent technological progress, the term has evolved significantly and shifted from a conceptual framework to a mechanistic understanding. This shift was accompanied by much hype and raised high hopes that epigenetics might hold both the key to deciphering the molecular underpinning of complex, non-Mendelian diseases and offer novel therapeutic approaches for a large panel of pathologies. However, while exciting reports of biological phenomena involving DNA methylation and histone modifications fill up the scientific literature, the realistic clinical applications of epigenetic medicines remain somewhat blurry. Here, we discuss the state of the art and speculate how epigenetics might contribute to prognostic and therapy approaches in the future.

  4. A new planar broadband antenna based on meandered line loops for portable wireless communication devices

    Science.gov (United States)

    Alibakhshi-Kenari, Mohammad; Naser-Moghadasi, Mohammad; Sadeghzadeh, R. A.; Virdee, Bal S.; Limiti, Ernesto

    2016-07-01

    This article presents the design of a novel planar antenna structure comprising two pairs of interconnected meandered line loops that are grounded to a truncated T-shaped ground plane through two via holes. The T-shaped ground plane is used as a reflector to enhance the performance of the antenna. The resulting antenna is compact occupying an area of 38.5 × 36.6 mm2 (0.070λo × 0.067λo), where free-space wavelength is 550 MHz. The antenna radiates omnidirectionally in the E plane across its operational bandwidth (550 MHz to 3.85 GHz) with peak gain and efficiency of 5.5 dBi and 90.1%, respectively, at 2.35 GHz and reflection coefficient better than -10 dB. These characteristics make the antenna suitable for numerous applications, in particular, JCDMA, UHF RFID, GSM 900, GPS, KPCS, DCS, IMT-2000, WiMAX, WiFi, and Bluetooth.

  5. Meandering Shallow Atmospheric Jet as a Model of Saturn's North-polar Hexagon

    Science.gov (United States)

    Morales-Juberías, R.; Sayanagi, K. M.; Simon, A. A.; Fletcher, L. N.; Cosentino, R. G.

    2015-06-01

    The Voyager flybys of Saturn in 1980-1981 revealed a circumpolar Hexagon at ˜78° north planetographic latitude that has persisted for over 30 Earth years, more than one Saturn year, and has been observed by ground-based telescopes, Hubble Space Telescope and multiple instruments on board the Cassini orbiter. Its average phase speed is very slow with respect to the System III rotation rate, defined by the primary periodicity in the Saturn Kilometric Radiation during the Voyager era. Cloud tracking wind measurements reveal the presence of a prograde jet-stream whose path traces the Hexagon’s shape. Previous numerical models have produced large-amplitude, n = 6, wavy structures with westward intrinsic phase propagation (relative to the jet). However, the observed net phase speed has proven to be more difficult to achieve. Here we present numerical simulations showing that instabilities in shallow jets can equilibrate as meanders closely resembling the observed morphology and phase speed of Saturn’s northern Hexagon. We also find that the winds at the bottom of the model are as important as the winds at the cloud level in matching the observed Hexagon’s characteristics.

  6. MEANDERING SHALLOW ATMOSPHERIC JET AS A MODEL OF SATURN'S NORTH-POLAR HEXAGON

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Juberías, R.; Cosentino, R. G. [Physics Department, New Mexico Institute of Mining and Technology, Socorro, NM 87801 (United States); Sayanagi, K. M. [Atmospheric and Planetary Sciences Department, Hampton University, Hampton VA 23668 (United States); Simon, A. A. [Solar System Exploration Division, NASA/GSFC, Greenbelt MD 20771 (United States); Fletcher, L. N., E-mail: rmjuberias@gmail.com [Atmospheric, Oceanic and Planetary Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom)

    2015-06-10

    The Voyager flybys of Saturn in 1980–1981 revealed a circumpolar Hexagon at ∼78° north planetographic latitude that has persisted for over 30 Earth years, more than one Saturn year, and has been observed by ground-based telescopes, Hubble Space Telescope and multiple instruments on board the Cassini orbiter. Its average phase speed is very slow with respect to the System III rotation rate, defined by the primary periodicity in the Saturn Kilometric Radiation during the Voyager era. Cloud tracking wind measurements reveal the presence of a prograde jet-stream whose path traces the Hexagon’s shape. Previous numerical models have produced large-amplitude, n = 6, wavy structures with westward intrinsic phase propagation (relative to the jet). However, the observed net phase speed has proven to be more difficult to achieve. Here we present numerical simulations showing that instabilities in shallow jets can equilibrate as meanders closely resembling the observed morphology and phase speed of Saturn’s northern Hexagon. We also find that the winds at the bottom of the model are as important as the winds at the cloud level in matching the observed Hexagon’s characteristics.

  7. An Optimized Circuit in Plastic Meander Line Antenna for 2.45 GHz Applications

    Directory of Open Access Journals (Sweden)

    Farhat Majeed

    2016-01-01

    Full Text Available Researchers seek to design electrically small planar antennas for RFID applications. Using multiparameter optimization, various meander line antennas were designed for the lowest resonant frequency and maximum radiation efficiencies for a fixed grid size. One such design for highest radiation efficiency was optimized for microwave frequencies by including an impedance matching structure. The antenna was printed with silver ink on a plexiglass substrate using the circuit in plastic (CiP technique of embedded electrical components. The measured scattering parameter (S11 was −18.43 dB at resonance. The radiation efficiency of the antenna measured using simple and improved Wheeler cap method was 74.4/74.1%. The radiation pattern of electrically small CiP antenna was doughnut-shaped with main lobe magnitude of 0.453 dB and an angular width of 84.2° in elevation plane. The measured 10 dB fractional bandwidth of the antenna was 18.98%. The results are compared with silver/copper in air antennas optimized for achieving the highest radiation efficiency for a fixed grid size. Plastic antennas are viable at microwave frequencies.

  8. Meandered conformai antenna for ISM-band ingestible capsule communication systems.

    Science.gov (United States)

    Arefin, Md Shamsul; Redoute, Jean-Michel; Yuce, Mehmet Rasit

    2016-08-01

    The wireless capsule has been used to measure physiological parameters in the gastrointestinal tract where communication from in-body to external receiver is necessary using a miniaturized antenna with high gain and onmidirectional radiation pattern. This paper presents a meandered conformal antenna with center frequency of 433 MHz for a wireless link between an in-body capsule system and an ex-body receiver system. The antenna is wrapped around the wireless capsule, which provides extra space for other circuits and sensors inside the capsule as well as allows it having larger dimensions compared to inner antennas. This paper analyses return loss, radiation pattern, antenna gain, and propagation loss using pork as the gastrointestinal tissue simulating medium. From the radiation pattern and return loss results, the antenna shows an omni-directional radiation pattern and an ultrawide bandwidth of 124.4 MHz (371.6 to 496 MHz) for VSWR <; 2. Experimental results shows that the path loss is 17.24 dB for an in-body propagation distance of 140 mm.

  9. Developmental analysis of GFAP immunoreactivity in the cerebellum of the meander tail mutant mouse.

    Science.gov (United States)

    Grishkat, H L; Schwartz, E; Jain, G; Eisenman, L M

    1996-08-01

    It is thought that Bergmann glial fibers assist in the inward migration of granule cells. Model systems in which there is a perturbation of either the migrating cells or the glial cell population have been useful in understanding the migratory process. In the meander tail mutant mouse, the anterior cerebellar region is agranular, whereas the posterior cerebellum is relatively unaffected by the mutation. This study presents a qualitative analysis of the development of cerebellar radial glia in mea/mea and +/mea mice aged from postnatal day 0 to adult, using an antibody against the glia specific antigen, glial fibrillary acidic protein. The results indicate a slight delay in the onset of immunoreactivity in the mea/mea cerebellum and abnormal glial formation in the anterior and posterior regions by postnatal day 5. At postnatal day 11, the full complement of labeled fibers appears to be present and although they appear abnormal in formation, they eventually reach the surface and terminate in oddly shaped and irregularly spaced endfeet. In adult mea/mea and +/mea mice, as compared to the early postnatal stages, there is a significant reduction in GFAP immunoreactive fibers. Cresyl violet stained adult mea/mea sections revealed the presence of ectopic granule cells in radial columns and small clumps at the surface of and within the molecular layer of the caudal cerebellum. Quantitative analyses revealed a 4- to 5-fold increase in the number of ectopic granule cells in lobule VIII of the mea/mea when compared with the +/mea cerebellum. These results suggest that the radial glia in the mea/mea cerebellum exhibit some uncharacteristic morphologies, but that these abnormalities are most likely the consequence of environmental alterations produced by the mutant gene.

  10. A 184-year record of river meander migration from tree rings, aerial imagery, and cross sections

    Science.gov (United States)

    Schook, Derek M.; Rathburn, Sara L.; Friedman, Jonathan M.; Wolf, J. Marshall

    2017-09-01

    Channel migration is the primary mechanism of floodplain turnover in meandering rivers and is essential to the persistence of riparian ecosystems. Channel migration is driven by river flows, but short-term records cannot disentangle the effects of land use, flow diversion, past floods, and climate change. We used three data sets to quantify nearly two centuries of channel migration on the Powder River in Montana. The most precise data set came from channel cross sections measured an average of 21 times from 1975 to 2014. We then extended spatial and temporal scales of analysis using aerial photographs (1939-2013) and by aging plains cottonwoods along transects (1830-2014). Migration rates calculated from overlapping periods across data sets mostly revealed cross-method consistency. Data set integration revealed that migration rates have declined since peaking at 5 m/year in the two decades after the extreme 1923 flood (3000 m3/s). Averaged over the duration of each data set, cross section channel migration occurred at 0.81 m/year, compared to 1.52 m/year for the medium-length air photo record and 1.62 m/year for the lengthy cottonwood record. Powder River peak annual flows decreased by 48% (201 vs. 104 m3/s) after the largest flood of the post-1930 gaged record (930 m3/s in 1978). Declining peak discharges led to a 53% reduction in channel width and a 29% increase in sinuosity over the 1939-2013 air photo record. Changes in planform geometry and reductions in channel migration make calculations of floodplain turnover rates dependent on the period of analysis. We found that the intensively studied last four decades do not represent the past two centuries.

  11. A 184-year record of river meander migration from tree rings, aerial imagery, and cross sections

    Science.gov (United States)

    Schook, Derek M.; Rathburn, Sara L.; Friedman, Jonathan M.; Wolf, J. Marshall

    2017-01-01

    Channel migration is the primary mechanism of floodplain turnover in meandering rivers and is essential to the persistence of riparian ecosystems. Channel migration is driven by river flows, but short-term records cannot disentangle the effects of land use, flow diversion, past floods, and climate change. We used three data sets to quantify nearly two centuries of channel migration on the Powder River in Montana. The most precise data set came from channel cross sections measured an average of 21 times from 1975 to 2014. We then extended spatial and temporal scales of analysis using aerial photographs (1939–2013) and by aging plains cottonwoods along transects (1830–2014). Migration rates calculated from overlapping periods across data sets mostly revealed cross-method consistency. Data set integration revealed that migration rates have declined since peaking at 5 m/year in the two decades after the extreme 1923 flood (3000 m3/s). Averaged over the duration of each data set, cross section channel migration occurred at 0.81 m/year, compared to 1.52 m/year for the medium-length air photo record and 1.62 m/year for the lengthy cottonwood record. Powder River peak annual flows decreased by 48% (201 vs. 104 m3/s) after the largest flood of the post-1930 gaged record (930 m3/s in 1978). Declining peak discharges led to a 53% reduction in channel width and a 29% increase in sinuosity over the 1939–2013 air photo record. Changes in planform geometry and reductions in channel migration make calculations of floodplain turnover rates dependent on the period of analysis. We found that the intensively studied last four decades do not represent the past two centuries

  12. Modeling the meander morphodynamics with internal boundary conditions given by a localized variation in the flow field

    Science.gov (United States)

    Lanzoni, S.; Bogoni, M.; Nittrouer, J. A.; Cantelli, A.

    2016-12-01

    Modeling of long-term evolution of meander planforms is usually applied to river reaches characterized by a uniform flow perturbed by the effects of the curvature and width distributions. However, in nature meandering rivers may be characterized by localized variations due to external conditions, e.g. changes in floodplain slope (geologic variation), confluence of a tributary into the main river (hydrologic variation), or backwater effects (hydrodynamic variation). As a consequence, the hypothesis of a sufficiently long reach having constant forcing characteristic could limit the reliability of the numerical simulations. We developed a mathematical extension of a well-known fully coupled two-dimensional morphodynamic model (i.e., the ZS model) able to manage an internally localized boundary condition which affects the characteristic of the main flow. The resulting modular model computes the flow field in the two meandering sub-reaches determined by the presence of a section entailing prescribed changes in external conditions, and simulates the long-term lateral migration above the floodplain surface due to erosion and deposition processes at the banks, and the possible occurrence of neck cutoffs. Calibration runs and simulations based on real test cases show that internal variations in the parameters controlling the flow field might strongly affect the morphodynamic behavior of the migrating planforms. Future research shall provide an extension of this approach in order to manage multiple internal boundary conditions within the investigated river reach. The aim is to relax the common hypothesis of a unique formative uniform flow, exploiting the less restrictive assumption of a sequence of uniform flows to describe the flow field that establishes in the river and controls its morphodynamic behaviour.

  13. Three-dimensional flow structure and patterns of bed shear stress in an evolving compound meander bend

    Science.gov (United States)

    Engel, Frank; Rhoads, Bruce L.

    2016-01-01

    Compound meander bends with multiple lobes of maximum curvature are common in actively evolving lowland rivers. Interaction among spatial patterns of mean flow, turbulence, bed morphology, bank failures and channel migration in compound bends is poorly understood. In this paper, acoustic Doppler current profiler (ADCP) measurements of the three-dimensional (3D) flow velocities in a compound bend are examined to evaluate the influence of channel curvature and hydrologic variability on the structure of flow within the bend. Flow structure at various flow stages is related to changes in bed morphology over the study timeframe. Increases in local curvature within the upstream lobe of the bend reduce outer bank velocities at morphologically significant flows, creating a region that protects the bank from high momentum flow and high bed shear stresses. The dimensionless radius of curvature in the upstream lobe is one-third less than that of the downstream lobe, with average bank erosion rates less than half of the erosion rates for the downstream lobe. Higher bank erosion rates within the downstream lobe correspond to the shift in a core of high velocity and bed shear stresses toward the outer bank as flow moves through the two lobes. These erosion patterns provide a mechanism for continued migration of the downstream lobe in the near future. Bed material size distributions within the bend correspond to spatial patterns of bed shear stress magnitudes, indicating that bed material sorting within the bend is governed by bed shear stress. Results suggest that patterns of flow, sediment entrainment, and planform evolution in compound meander bends are more complex than in simple meander bends. Moreover, interactions among local influences on the flow, such as woody debris, local topographic steering, and locally high curvature, tend to cause compound bends to evolve toward increasing planform complexity over time rather than stable configurations.

  14. Flow Patterns and Morphological Changes in a Sandy Meander Bend during a Flood—Spatially and Temporally Intensive ADCP Measurement Approach

    Directory of Open Access Journals (Sweden)

    Elina Kasvi

    2017-02-01

    Full Text Available The fluvio-geomorphological processes in meander bends are spatially uneven in distribution. Typically, higher velocities and erosion take place near the outer bank beyond the bend apex, while the inner bend point bar grows laterally towards the outer bank, increasing the bend amplitude. These dynamics maintain the meander evolution. Even though this development is found in meandering rivers independent of soil or environmental characteristics, each river still seems to behave unpredictably. The special mechanisms that determine the rate and occasion of morphological changes remain unclear. The aim of this study is to offer new insights regarding flow-induced morphological changes in meander using a novel study approach. We focused on short-term and small-spatial-scale changes by conducting a spatially and temporally (daily intensive survey during a flood (a period of nine days with an ADCP attached to a remotely controlled mini-boat. Based on our analysis, the flood duration and the rate of discharge increase and decrease seems to play key roles in determining channel changes by controlling the flow velocities and depth and the backwater effect may have notable influence on the morphological processes. We discuss themes such as the interaction of inner and outer bend processes and the longer-term development of meander bends.

  15. Drifting and meandering of Olive Ridley Sea turtles in the Bay of Bengal: Role of oceanic Rossby waves

    Digital Repository Service at National Institute of Oceanography (India)

    Ram, P.S.; Rao, S.A.; Sadhuram, Y.

    in the direction of geostrophic currents. It is found that the locations of these thermal fronts in the Bay of Bengal are primarily determined by the Oceanic Rossby waves and local Ekman pumping. Key Words: Bay of Bengal, Circulation, Cyclonic and Anti... drawn with black dots shows the meandering path of the rest of the three turtles. Locations of the turtles at different times are also shown as white stars. A strong anti-cyclonic gyre (warm core eddy) centered at 17º N with SSHD above 30 cm...

  16. Magnetic fingerprint of the sediment load in a meander bend section of the Seine River (France)

    Science.gov (United States)

    Kayvantash, D.; Cojan, I.; Kissel, C.; Franke, C.

    2017-06-01

    This study aims to evaluate the potential of magnetic methods to determine the composition of the sediment load in a cross section of an unmanaged meander in the upstream stretch of the Seine River (Marnay-sur-Seine). Suspended particulate matter (SPM) was collected based on a regular sampling scheme along a cross section of the river, at two different depth levels: during a low-water stage (May 2014) and a high-water stage (February 2015). Riverbed sediments (RBS) were collected during the low-water stage and supplementary samples were taken from the outer and inner banks. Magnetic properties of the dry bulk SPM and sieved RBS and bank sediments were analysed. After characterizing the main magnetic carrier as magnetite, hysteresis parameters were measured, giving access to the grain size and the concentration of these magnetite particles. The results combined with sedimentary grain size data were compared to the three-dimensional velocity profile of the river flow. In the RBS where the magnetic grain size is rather uniform, the concentration of magnetite is inversely proportional to the mean grain size of the total sediment indicating that magnetite is strongly associated with the fine sedimentary fraction. The same pattern is observed in the samples from the outer and inner banks. During the low-water stage, the uniformly fine SPM grain size distribution characterizes the wash load. The magnetic fraction is also relatively fine (within the pseudo single domain range) with concentration similar to that of the fine RBS fraction. During the high-water stage, SPM samples correspond to mixtures of wash load and resuspended sediment from the bedload and riverbanks. Here, the grain size distribution is heterogeneous across the section showing coarser particles compared to those in the low-water stage and more varying magnetite concentrations while the magnetic grain size is like that of the low-water stage. The magnetite concentration in the high-water SPM can be

  17. Meandering main pancreatic duct as a relevant factor to the onset of idiopathic recurrent acute pancreatitis.

    Directory of Open Access Journals (Sweden)

    Wataru Gonoi

    Full Text Available BACKGROUND: Meandering main pancreatic duct (MMPD, which comprises loop type and reverse-Z type main pancreatic duct (MPD, has long been discussed its relation to pancreatitis. However, no previous study has investigated its clinical significance. We aimed to determine the non-biased prevalence and the effect of MMPD on idiopathic pancreatitis using non-invasive magnetic resonance (MR technique. METHODS AND FINDINGS: A cross-sectional study performed in a tertiary referral center. The study enrolled 504 subjects from the community and 30 patients with idiopathic pancreatitis (7 acute, 13 chronic, and 10 recurrent acute. All subjects underwent MR scanning and medical examination. MMPD was diagnosed when the MPD in the head of pancreas formed two or more extrema in the horizontal direction on coronal images of MR cholangiopancreatography, making a loop or a reverse-Z shaped hairpin curves and not accompanied by other pancreatic ductal anomaly. Statistical comparison was made among groups on the rate of MMPD including loop and reverse-Z subtypes, MR findings, and clinical features. The rate of MMPD was significantly higher for all idiopathic pancreatitis/idiopathic recurrent acute pancreatitis (RAP (20%/40%; P<0.001/0.0001; odds ratio (OR, 11.1/29.0 than in the community (2.2% but was not higher for acute/chronic pancreatitis (14%/8%; P = 0.154/0.266. Multiple logistic regression analysis revealed MMPD to be a significant factor that induces pancreatitis/RAP (P<0.0001/0.0001; OR, 4.01/26.2. Loop/reverse-Z subtypes were found more frequently in idiopathic RAP subgroup (20%/20%; P = 0.009/0.007; OR, 20.2/24.2 than in the community (1.2%/1.0%. The other clinical and radiographic features were shown not associated with the onset of pancreatitis. CONCLUSIONS: MMPD is a common anatomical variant and might be a relevant factor to the onset of idiopathic RAP.

  18. Minimizing the Error Associated With Measurements of Migration-Related Sediment Exchange on Meandering Rivers

    Science.gov (United States)

    Lauer, J. W.; Parker, G.

    2005-05-01

    The floodplains of meandering rivers represent reservoirs that both store and release sediment. Bed material is generally released from cut banks and replaced in nearby point bars wherever migration occurs. Measuring the associated bed material flux is important for tracing the movement of contaminants that may be mixed with the bed material. Approximations of this flux can be made using a representative channel depth and sequences of aerial photography to estimate average absolute migration rates (or reworked areas) between photographs. Error in the aerial photographs leads to a positive bias in computed release rates. A method for removing this bias is introduced that uses the apparent offset of fixed linear features such as roads (along smaller rivers) or abandoned channel courses (along larger rivers). Measuring the rate of release of fine sediment is important both for predicting the long term morphodynamic evolution of the channel/floodplain system and for tracing the movement of contaminants that may be adsorbed to the fine sediment. While fine sediment can be mixed throughout the depth of the floodplain, it is most concentrated in the upper portion of older parts of the floodplain where it has had time to accumulate through overbank deposition. Its release rate can be estimated using migration rates computed from aerial photography in combination with local measurements of bank topography, both of which are highly variable even within a given reach. Where detailed bank topography is available for an entire reach, estimating the release of fine sediment is relatively straightforward. However, detailed topography is often unavailable along the banks of large lowland rivers, forcing estimates of the fine material flux to be made using a relatively small number of physically surveyed cross-sections. It is not immediately clear how many cross sections are required for a good estimate. This study performs Monte Carlo simulations on a detailed topographic dataset

  19. The performance of the Hydromorphological Index of Diversity (HMID) in a hydropower affected meandering river

    Science.gov (United States)

    Stähly, Severin; Bourqui, Pierre; Franca, Mario J.; Robinson, Christopher; Schleiss, Anton J.

    2016-04-01

    More than half of the Swiss electricity is produced by hydropower. Large price fluctuations cause severe hydropeaking flow regimes due to corresponding production fluctuations, which undisputedly have a negative impact on aquatic biota. Water diversion due to dams on the other hand imposes downstream residual flow regimes. The absence of flood events and regular sediment supply disrupts sediment dynamics and disconnects floodplains, which are habitats of high value, from its main channel. The residual-flow controlled reach at the Sarine river in western Switzerland is the subject of the present study. The Sarine meanders strongly and the river reach under analysis has a bed incision of locally more than 100 m. Its incision provokes the isolation of the river which is consequently minimally touched by human structures and shows a natural geomorphology. Since the construction of a dam upstream this reach in 1948, aiming at the water abstraction to hydropower, vegetation could establish and the active floodplain decreased its area, as airborne images show. Nevertheless, it is classified as a floodplain of national importance and it has been under protection since 1992. It is supposed to be a valuable habitat for a wide range of organisms. The Hydromorphological Index of Diversity (HMID) is a simple tool for quantifying the habitat richness in a river reach, taking into account the mean values and the variation of water depth and flow velocity. For channelized rivers, HMID values from up to 5 are expected, while morphological pristine sites with a high spatial variability of water depth and velocity show values of 9 or higher. For the residual flow of the Sarine River, flow depth and velocity were measured using ADCP and ADV. The results are compared with a nearby natural reference river and the outcome of a 2D numerical simulation. Finally, the behaviour and limitations of the HMID, in a hydropower affected river, are discussed. In the close future an artificial flood

  20. Stratification effects on flow field and bed topography in meandering rivers

    Science.gov (United States)

    Bolla Pittaluga, M.

    2010-12-01

    and eddy diffusivity, enhances significantly the vertical distribution of lateral velocity. Next, we investigate whether the point bar pattern in the inner bank and pool in the outer bank typically observed in meandering rivers may be significantly affected by the stratification effect. With the help of the Exner equation we show that, in the ideal case analyzed here, namely a uniform and steady flow in a constant curvature channel, stratification gives rise to steeper lateral bed profiles with respect to the unstratified case.

  1. Developmental analysis of the external granular layer in the meander tail mutant mouse: do cerebellar microneurons have independent progenitors?

    Science.gov (United States)

    Napieralski, J A; Eisenman, L M

    1993-08-01

    The cerebellum of the meander tail mutant mouse (mea/mea) is characterized by an apparently normal cytoarchitecture posteriorly with an abrupt transition to an abnormal anterior region. Anteriorly, there is abnormal foliation, a drastic reduction in the granule cells (GC) population, disorganization of the Purkinje cells (PC), and a virtual absence of Bergmann glial processes. In this paper we analyze the prenatal and postnatal development of the cerebellum in the mea/mea and attempt to determine the phenotypic onset of the mutation in the anterior region. Hematoxylin and eosin stained sections reveal a morphological difference in the cerebellum of the mea/mea as early as embryonic day 16 characterized by a reduction in the external granule cell layer (EGL). The reduction in the EGL becomes increasingly apparent as development proceeds. This deficit in the EGL most probably results in the absence of GC, but it is unclear at this point whether reduced migration, proliferation, and/or increased cell death is the major factor. Interestingly, immunohistochemical staining with a monoclonal antibody against parvalbumin reveals that the basket and stellate cells, which are also thought to arise from the EGL, are present in the anterior region of the mea/mea cerebellum. These results suggest that the lack of GC in the meander tail is due to an early expressed abnormality of the EGL. However, the presence of the basket and/or stellate cells raises some interesting questions concerning the lineage of the cerebellar microneurons.

  2. 2D NUMERICAL SIMULATION OF FLOOD AND FLUVIAL PROCESS IN THE MEANDERING AND ISLAND-BRAIDED MIDDLE YANGTZE RIVER

    Institute of Scientific and Technical Information of China (English)

    Yong-jun LU; Zhao-yin WANG; Li-qin ZUO; Li-jun ZHU

    2005-01-01

    The characteristics of water flow and sediment transport in a typical meandering and island-braided reach of the middle Yangtze River is investigated using a two-dimensional (2D)mathematical model. The major problems studied in the paper include the carrying capacity for suspended load, the incipient velocity and transport formula of non-uniform sediment, the thickness of the mixed layer on the riverbed, and the partitioning of bed load and suspended load. The model parameters are calibrated using extensive field data. Water surface profiles, distribution of flow velocities, riverbed deformation are verified with site measurements. The model is applied to a meandering and island-braided section of the Wakouzi-Majiazui reach in the middle Yangtze River,which is about 200 km downstream from the Three Gorges Dam, to study the training scheme of the navigation channels. The model predicts the processes of sediment deposition and river bed erosion,changes of flow stage and navigation conditions for the first 20 years of impoundment of the Three Gorges Project.

  3. Identifying sensitive areas of adaptive observations for prediction of the Kuroshio large meander using a shallow-water model

    Science.gov (United States)

    Zou, Guang'an; Wang, Qiang; Mu, Mu

    2016-09-01

    Sensitive areas for prediction of the Kuroshio large meander using a 1.5-layer, shallow-water ocean model were investigated using the conditional nonlinear optimal perturbation (CNOP) and first singular vector (FSV) methods. A series of sensitivity experiments were designed to test the sensitivity of sensitive areas within the numerical model. The following results were obtained: (1) the eff ect of initial CNOP and FSV patterns in their sensitive areas is greater than that of the same patterns in randomly selected areas, with the eff ect of the initial CNOP patterns in CNOP sensitive areas being the greatest; (2) both CNOP- and FSV-type initial errors grow more quickly than random errors; (3) the eff ect of random errors superimposed on the sensitive areas is greater than that of random errors introduced into randomly selected areas, and initial errors in the CNOP sensitive areas have greater eff ects on final forecasts. These results reveal that the sensitive areas determined using the CNOP are more sensitive than those of FSV and other randomly selected areas. In addition, ideal hindcasting experiments were conducted to examine the validity of the sensitive areas. The results indicate that reduction (or elimination) of CNOP-type errors in CNOP sensitive areas at the initial time has a greater forecast benefit than the reduction (or elimination) of FSV-type errors in FSV sensitive areas. These results suggest that the CNOP method is suitable for determining sensitive areas in the prediction of the Kuroshio large-meander path.

  4. Printed Notched Antenna with Long Meandered Line for Eight-Band LTE/GSM/UMTS Wireless USB Dongle Operation

    Science.gov (United States)

    Zhang, Y. H.; Sun, S. C.; Ban, Y. L.; Tang, X. H.

    2016-03-01

    This paper presents a planar notched antenna with a long meandered line for wireless USB dongle applications. The printed notched structure is used as additional resonators to generate multiple bands operation for covering GSM1800/1900/UMTS2100/LTE2300/2500 bands. In addition, with the help of the long meandered line via hole to ground, a lower resonant mode is sufficiently generated at around 770 MHz and forms a wider lower operating bandwidth (LTE700/GSM850/900). Briefly printed on a 0.8 mm thick FR4 dielectric substrate of size 20×70 mm² and electrically connected (via hole) to the ground plane of the USB dongle, the proposed antenna can provide a wide operating bandwidth (3:1 VSWR) of larger than 120 % centered at 2,000 MHz, allowing it to cover 698-960 and 1,710-2,690 MHz bands. The proposed antenna also can be attached to laptop computer by the USB interface. Detailed design considerations of the proposed antenna are described, and obtained experimental and simulation results are also presented and discussed in this paper.

  5. Geophysical controls of aquifer-river exchange flow patterns in a UK lowland meandering river.

    Science.gov (United States)

    Dara, Rebwar; Krause, Stefan; Rivett, Michael

    2016-04-01

    The deposition of fine particles (clay and silt) and organic matters in alluvial sediments can substantially reduce the permeability of streambed sediments and extend towards the wider floodplain. The resulting hydraulic conductivity patterns within the streambed and floodplain have been shown to control both location as well as intensity of hyporheic exchange in many lowland rivers. The aim of the study is to investigate the variability in streambed permeability fields in an unprecedented spatial resolution and quantify the impacts on controlling hyporheic exchange fluxes in the River Tern, a UK lowland meandering stream. Geophysical surveys were conducted deploying Ground Penetrating Radar (GPR) in conjunction with geological information derived from core logs and bank exposures for mapping shallow subsurface structural heterogeneity. The GPR survey deployed a pulse EKKO pro equipped with a shielded 250 MHz antenna. For the floodplain survey, GPR profiles of 12 NE-SW and 6 NW- SE orientation profiles were taken creating a raster of approximately 10 m. The riparian terrestrial GPR surveys were accompanied by a longitudinal in channel GPR survey for which the antenna was deployed on a floating device. At locations identified to be representative for the range of streambed hydrofacies identified by GPR in investigated stream reach, multi-level mini-piezometer networks were installed in the streambed for monitoring groundwater-surface water exchange fluxes, and conducting dilution tracer tests for quantification of residence time distributions at the aquifer-river interface. Quasi-three-dimensional GPR profiles from closely spaced grids of 2D GPR data of floodplain deposits indicated a range of different radar facies and helped to delineate the type and extend of high and low conductive materials. The results of longitudinal GPR survey along a 240 m section of the river channel revealed that areas rich in low conductivity layers such as organic peat and clay lenses

  6. Fates of pollutants from uranium mining in floodplain of a meandering river (the Ploucnice, Czech Republic)

    Science.gov (United States)

    Matys Grygar, Tomas; Elznicova, Jitka; Majerova, Lucie; Babek, Ondrej; Kiss, Timea; Havelcova, Martina; Hosek, Michal

    2014-05-01

    tens of km downstream of the mining area). Several hotspots were formed behind the end of the channelised river reach downstream from the mining area. The analyses of the pollution hotspots conducted by other researchers in 1990s and our novel results show that maximal pollutant gamma activity (mainly U and Ra-226) in these hotspots has been transported from a meander (channel) belt towards the distal floodplain. Downstream transport (secondary pollution) from the hotspots is demonstrated by considerable Zn, Ni and U enrichment in the deposits of 2013 summer flood (25 years after termination of the primary pollution) and by the fact, that enrichment factors of Zn, Ni and U in the floodplain sediments downstream of the hotspots has still not started to decline. The persistence of the pollution of the floodplain sediments is in contrast with the activity of the Ploučnice River water, which dropped down in 1989 and afterwards to the levels from the period before the start of the uranium mining.

  7. Comparison of the Dynamic Wake Meandering Model, Large-Eddy Simulation, and Field Data at the Egmond aan Zee Offshore Wind Plant: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Churchfield, M. J.; Moriarty, P. J.; Hao, Y.; Lackner, M. A.; Barthelmie, R.; Lundquist, J.; Oxley, G. S.

    2014-12-01

    The focus of this work is the comparison of the dynamic wake meandering model and large-eddy simulation with field data from the Egmond aan Zee offshore wind plant composed of 36 3-MW turbines. The field data includes meteorological mast measurements, SCADA information from all turbines, and strain-gauge data from two turbines. The dynamic wake meandering model and large-eddy simulation are means of computing unsteady wind plant aerodynamics, including the important unsteady meandering of wakes as they convect downstream and interact with other turbines and wakes. Both of these models are coupled to a turbine model such that power and mechanical loads of each turbine in the wind plant are computed. We are interested in how accurately different types of waking (e.g., direct versus partial waking), can be modeled, and how background turbulence level affects these loads. We show that both the dynamic wake meandering model and large-eddy simulation appear to underpredict power and overpredict fatigue loads because of wake effects, but it is unclear that they are really in error. This discrepancy may be caused by wind-direction uncertainty in the field data, which tends to make wake effects appear less pronounced.

  8. Single Wake Meandering, Advection and Expansion - An analysis using an adapted Pulsed Lidar and CFD LES-ACL simulations

    DEFF Research Database (Denmark)

    In this paper, single wake characteristics have been studied both experimentally and numerically. Firstly, the wake is studied experimentally using full-scale measurements from an adapted focused pulsed lidar system, which potentially gives more insight into the wake dynamics as compared to class...... using the EllipSys3D flow solver using Large Eddy Simulation (LES) and Actuator Line Technique (ACL) to model the rotor. Discrepancies due to the uncertainties on the wake advection velocity are observed and discussed....... of the wake, and it is compared to the predictions from the Dynamic Wake Meandering model, for a selected 10 minutes dataset. Secondly, the average wake expansion in the fixed frame of reference is determined from measurements and compared to results from CFD simulations. The CFD simulations were conducted...

  9. Single Wake Meandering, Advection and Expansion - An analysis using an adapted Pulsed Lidar and CFD LES-ACL simulations

    DEFF Research Database (Denmark)

    Machefaux, Ewan; Larsen, Gunner Chr.; Troldborg, Niels;

    2013-01-01

    In this paper, single wake characteristics have been studied both experimentally and numerically. Firstly, the wake is studied experimentally using full-scale measurements from an adapted focused pulsed lidar system, which potentially gives more insight into the wake dynamics as compared to class...... using the EllipSys3D flow solver using Large Eddy Simulation (LES) and Actuator Line Technique (ACL) to model the rotor. Discrepancies due to the uncertainties on the wake advection velocity are observed and discussed....... of the wake, and it is compared to the predictions from the Dynamic Wake Meandering model, for a selected 10 minutes dataset. Secondly, the average wake expansion in the fixed frame of reference is determined from measurements and compared to results from CFD simulations. The CFD simulations were conducted...

  10. Quantifying process-based mitigation strategies in historical context: separating multiple cumulative effects on river meander migration.

    Directory of Open Access Journals (Sweden)

    Alexander K Fremier

    Full Text Available Environmental legislation in the US (i.e. NEPA requires defining baseline conditions on current rather than historical ecosystem conditions. For ecosystems with long histories of multiple environmental impacts, this baseline method can subsequently lead to a significantly altered environment; this has been termed a 'sliding baseline'. In river systems, cumulative effects caused by flow regulation, channel revetment and riparian vegetation removal significantly impact floodplain ecosystems by altering channel dynamics and precluding subsequent ecosystem processes, such as primary succession. To quantify these impacts on floodplain development processes, we used a model of river channel meander migration to illustrate the degree to which flow regulation and riprap impact migration rates, independently and synergistically, on the Sacramento River in California, USA. From pre-dam conditions, the cumulative effect of flow regulation alone on channel migration is a reduction by 38%, and 42-44% with four proposed water diversion project scenarios. In terms of depositional area, the proposed water project would reduce channel migration 51-71 ha in 130 years without current riprap in place, and 17-25 ha with riprap. Our results illustrate the utility of a modeling approach for quantifying cumulative impacts. Model-based quantification of environmental impacts allow scientists to separate cumulative and synergistic effects to analytically define mitigation measures. Additionally, by selecting an ecosystem process that is affected by multiple impacts, it is possible to consider process-based mitigation scenarios, such as the removal of riprap, to allow meander migration and create new floodplains and allow for riparian vegetation recruitment.

  11. Temperature, salinity, and oxygen; measured with a Seabird CTD system; The Anatomy of Gulf Stream Meanders; Fall of 1988 and Spring of 1989; Gulf Stream region South of Cape Cod (NODC Accession 9900100)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The object was to probe in greater detail than has been possible in the past, the dynamical balances of Gulf Stream meanders and their change with time....

  12. Hyporheic Exchange Flows and Biogeochemical Patterns near a Meandering Stream: East Fork of the Jemez River, Valles Caldera National Preserve, New Mexico

    Science.gov (United States)

    Christensen, H.; Wooten, J. P.; Swanson, E.; Senison, J. J.; Myers, K. D.; Befus, K. M.; Warden, J.; Zamora, P. B.; Gomez, J. D.; Wilson, J. L.; Groffman, A.; Rearick, M. S.; Cardenas, M. B.

    2012-12-01

    A study by the 2012 Hydrogeology Field Methods class of the University of Texas at Austin implemented multiple approaches to evaluate and characterize local hyporheic zone flow and biogeochemical trends in a highly meandering reach of the of the East Fork of the Jemez River, a fourth order stream in northwestern New Mexico. This section of the Jemez River is strongly meandering and exhibits distinct riffle-pool morphology. The high stream sinuosity creates inter-meander hyporheic flow that is also largely influenced by local groundwater gradients. In this study, dozens of piezometers were used to map the water table and flow vectors were then calculated. Surface water and ground water samples were collected and preserved for later geochemical analysis by ICPMS and HPLC, and unstable parameters and alkalinity were measured on-site. Additionally, information was collected from thermal monitoring of the streambed, stream gauging, and from a series of electrical resistivity surveys forming a network across the site. Hyporheic flow paths are suggested by alternating gaining and losing sections of the stream as determined by stream gauging at multiple locations along the reach. Water table maps and calculated fluxes across the sediment-water interface also indicate hyporheic flow paths. We find variability in the distribution of biogeochemical constituents (oxidation-reduction potential, nitrate, ammonium, and phosphate) along interpreted flow paths which is partly consistent with hyporheic exchange. The variability and heterogeneity of reducing and oxidizing conditions is interpreted to be a result of groundwater-surface water interaction. Two-dimensional mapping of biogeochemical parameters show redox transitions along interpreted flow paths. Further analysis of various measured unstable chemical parameters results in observable trends strongly delineated along these preferential flow paths that are consistent with the direction of groundwater flow and the assumed

  13. A Compact Symmetric Microstrip Filter Based on a Rectangular Meandered-Line Stepped Impedance Resonator with a Triple-Band Bandstop Response

    Directory of Open Access Journals (Sweden)

    Rajendra Dhakal

    2013-01-01

    Full Text Available This paper presents a symmetric-type microstrip triple-band bandstop filter incorporating a tri-section meandered-line stepped impedance resonator (SIR. The length of each section of the meandered line is 0.16, 0.15, and 0.83 times the guided wavelength (λg, so that the filter features three stop bands at 2.59 GHz, 6.88 GHz, and 10.67 GHz, respectively. Two symmetric SIRs are employed with a microstrip transmission line to obtain wide bandwidths of 1.12, 1.34, and 0.89 GHz at the corresponding stop bands. Furthermore, an equivalent circuit model of the proposed filter is developed, and the model matches the electromagnetic simulations well. The return losses of the fabricated filter are measured to be −29.90 dB, −28.29 dB, and −26.66 dB while the insertion losses are 0.40 dB, 0.90 dB, and 1.10 dB at the respective stop bands. A drastic reduction in the size of the filter was achieved by using a simplified architecture based on a meandered-line SIR.

  14. Research on 3D Distribution of Meandering River Sand Body Using Sedimentary Facies Method and 3D Geological Modeling

    Institute of Scientific and Technical Information of China (English)

    WU Jian; CAO Dai-yong

    2006-01-01

    Sedimentary facies study is an important method in describing the property and distribution of reservoir. 3D geological modeling is a powerful tool in 3D characterization of geological bodies. By combining the sedimentary facies study with 3D geological modeling to generate 3D sedimentary facies model, the 3D geometry and distribution feature of sand bodies can be more accurately characterized, particularly in 3D view. In Liuchu oilfield of Jizhong depression, the Ed2IV formation was recognized as meandering river deposition facies and five sedimentary facies were identified, which include point bar sand, levee, channel margin, abandoned channel and floodplain. All the 24 sand body facies in Ed2IV were mapped and the 3D sedimentary facies model established based on 2D facies maps. The result shows that the 3D sedimentary facies model is well matched for the research result of sedimentary facies. Being an extension of traditional sedimentary study, the 3D sedimentary facies model can be used to describe the 3D geometry and distribution orders of a single sand body more reliably and more accurately.

  15. THREE-DIMENSIONAL SIMULATION OF MEANDERING RIVER BASED ON 3-D RNG k-ε TURBULENCE MODEL

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ming-liang; SHEN Yong-ming

    2008-01-01

    A 3-D numerical model for calculating flow in non-curvilinear coordinates was established in this article. The flow was simulated by solving the full Reynolds-averaged Navier-Stokes equations with the RNG k-ε turbulence model. In the horizontal x-y-plane, a boundary-fitted curvilinear co-ordinate system was adopted, while in the vertical direction, a co-ordinate transformation was used to represent the free surface and bed topography. The water level was determined by solving the 2-D Poisson equation derived from 2-D depth averaged momentum equations. The finite-volume method was used to discretize the equations and the SIMPLEC algorithm was applied to acquire the coupling of velocity and pressure. This model was applied to simulate the meandering channels and natural rivers, and the water levels and the velocities for all sections were given. By contrasting and analyzing, the agreement with measurements is generally good. The feasibility studies of simulating flow of the natural river have been conducted to demonstrate its applicability to hydraulic engineering research.

  16. Geomorphic and vegetation changes in a meandering dryland river regulated by a large dam, Sauce Grande River, Argentina

    Science.gov (United States)

    Casado, Ana; Peiry, Jean-Luc; Campo, Alicia M.

    2016-09-01

    This paper investigates post-dam geomorphic and vegetation changes in the Sauce Grande River, a meandering dryland river impounded by a large water-conservation dam. As the dam impounds a river section with scarce influence of tributaries, sources for fresh water and sediment downstream are limited. Changes were inspected based on (i) analysis of historical photographs/imagery spanning pre- (1961) and post-dam (1981, 2004) channel conditions for two river segments located above and below the dam, and (ii) field survey of present channel conditions for a set of eight reference reaches along the river segments. Whilst the unregulated river exhibited active lateral migration with consequent adjustments of the channel shape and size, the river section below the dam was characterized by (i) marked planform stability (93 to 97%), and by (ii) vegetation encroachment leading to alternating yet localized contraction of the channel width (up to 30%). The present river displays a moribund, stable channel where (i) redistribution of sediment along the river course no longer occurs and (ii) channel forms constitute a remnant of a fluvial environment created before closing the dam, under conditions of higher energy. In addition to providing new information on the complex geomorphic response of dryland rivers to impoundment, this paper represents the very first geomorphic assessment of the regulated Sauce Grande and therefore provides an important platform to underpin further research assessing the geomorphic state of this highly regulated dryland river.

  17. Hub vortex helical instability as the origin of wake meandering in the lee of a model wind-turbine

    Science.gov (United States)

    Viola, Francesco; Iungo, Giacomo Valerio; Camarri, Simone; Porte-Agel, Fernando; Gallaire, Francois

    2012-11-01

    Wind tunnel measurements were performed for the wake produced by a three-bladed wind turbine immersed in uniform flow. These tests show the presence of a vorticity structure in the near wake region mainly oriented along the streamwise direction, which is denoted as hub vortex. The hub vortex is characterized by oscillations with frequencies lower than the one connected to the rotational velocity of the rotor, which are ascribed to wake meandering by previous works. This phenomenon consists in transversal oscillations of the wind turbine wake, which are excited by the shedding of vorticity structures from the rotor disc acting as a bluff body. In this work temporal and spatial linear stability analyses of a wind turbine wake are performed on a base flow obtained through time-averaged wind tunnel velocity measurements. This study shows that the low frequency spectral component detected experimentally is the result of a convective instability of the hub vortex, which is characterized by a counter-winding single-helix structure. Simultaneous hot-wire measurements confirm the presence of a helicoidal unstable mode of the hub vortex with a streamwise wavenumber roughly equal to the one predicted from the linear instability analysis.

  18. 一种新型微带曲折线慢波结构的设计%Design of a New Microstrip Meander-Line Slow Wave Structure

    Institute of Scientific and Technical Information of China (English)

    陈常婷; 宫玉彬; 沈飞; 魏彦玉; 王文祥

    2011-01-01

    设计了一种新型微带曲折线慢波结构,该结构采用双介质杆支撑式的V型平面曲折线慢波电路.利用电磁场仿真软件HFSS对这种新型结构和传统微带曲折线慢波结构进行了分析比较,研究结果表明,新型微带曲折线慢波结构在不改变色散强弱的情况下,工作频段向高频端拓展且耦合阻抗有了很大提高,可以更好地工作在短毫米波段.并仿真分析了结构参数对高频特性的影响,所获得的仿真结果为器件的粒子模拟及计算慢波结构的工作效率奠定了基础.%A new microstrip meander-line slow wave structure was designed, which uses the V-type plane meander-line slow wave circuit with twin dielectric-strips.The performances of the new microstrip meander-line slow wave structure and the traditional meander-line slow wave structure were compared by using of the electromagnetic simulation software HFSS.The effects of different structural parameters on the new structure were analyzed.The simulation results show that the new microstrip meander-line slow wave structure has a similar dispersion characteristic with the traditional structure, and the center frequency expands to the higher frequency, and the coupling impedance is greatly improved.Hence the new structure can work much better in millimeter wave band.The results lay a good foundation for particle-in-cell (PIC) simulation and efficiency caculation.

  19. Degree of Contamination and Sources of Polychlorinated Biphenyls in Meandering Road Creek and Woods Inlet of Lake Worth, Fort Worth, Texas, 2004 and 2006-07

    Science.gov (United States)

    Braun, Christopher L.; Wilson, Jennifer T.; Van Metre, Peter C.

    2008-01-01

    Lake Worth is a reservoir on the West Fork Trinity River on the western edge of Fort Worth, Texas. Air Force Plant 4 (AFP4) is on the eastern shore of Woods Inlet, an arm of Lake Worth that extends south from the main body of the lake. Two previous reports documented ele-vated polychlorinated biphenyl (PCB) concentrations in surficial sediment in Woods Inlet relative to those in surficial sediment in other parts of Lake Worth. This report presents the results of another USGS study, done in cooperation with the U.S. Air Force, to indicate the degree of PCB contamination of Meandering Road Creek and Woods Inlet and to identify possible sources of PCBs in Meandering Road Creek and Woods Inlet on the basis of suspended, streambed, and lake-bottom sediment samples collected there in 2004 and 2006-07. About 40 to 80 percent of total PCB concentrations (depending on how total PCB concentration is computed) in suspended sediment exceed the threshold effect concentration, a concentration below which adverse effects to benthic biota rarely occur. About 20 percent of total PCB concentrations (computed as sum of three Aroclors) in suspended sediment exceed the probable effect concentration, a concentration above which adverse effects to benthic biota are expected to occur frequently. About 20 to 30 percent of total PCB concentrations in streambed sediment exceed the threshold effect concentration; and about 6 to 20 percent of total PCB concentrations in lake-bottom (Woods Inlet) sediment exceed the threshold effect concentration. No streambed or lake-bottom sediment concentrations exceed the probable effect concentration. The sources of PCBs to Meandering Road Creek and Woods Inlet were investigated by comparing the relative distributions of PCB congeners of suspended sediment to those of streambed and lake-bottom sediment. The sources of PCBs were identified using graphical analysis of normalized concentrations (congener ratios) of 11 congeners. For graphical analysis, the

  20. Application of the conditional nonlinear optimal perturbation method to the predictability study of the Kuroshio large meander

    Science.gov (United States)

    Wang, Qiang; Mu, Mu; Dijkstra, Henk A.

    2012-01-01

    A reduced-gravity barotropic shallow-water model was used to simulate the Kuroshio path variations. The results show that the model was able to capture the essential features of these path variations. We used one simulation of the model as the reference state and investigated the effects of errors in model parameters on the prediction of the transition to the Kuroshio large meander (KLM) state using the conditional nonlinear optimal parameter perturbation (CNOP-P) method. Because of their relatively large uncertainties, three model parameters were considered: the interfacial friction coefficient, the wind-stress amplitude, and the lateral friction coefficient. We determined the CNOP-Ps optimized for each of these three parameters independently, and we optimized all three parameters simultaneously using the Spectral Projected Gradient 2 (SPG2) algorithm. Similarly, the impacts caused by errors in initial conditions were examined using the conditional nonlinear optimal initial perturbation (CNOP-I) method. Both the CNOP-I and CNOP-Ps can result in significant prediction errors of the KLM over a lead time of 240 days. But the prediction error caused by CNOP-I is greater than that caused by CNOP-P. The results of this study indicate not only that initial condition errors have greater effects on the prediction of the KLM than errors in model parameters but also that the latter cannot be ignored. Hence, to enhance the forecast skill of the KLM in this model, the initial conditions should first be improved, the model parameters should use the best possible estimates.

  1. Application of the Conditional Nonlinear Optimal Perturbation Method to the Predictability Study of the Kuroshio Large Meander

    Institute of Scientific and Technical Information of China (English)

    WANG Qiang; MU Mu; Henk A. DIJKSTRA

    2012-01-01

    A reduced-gravity barotropic shallow-water model was used to simulate the Kuroshio path variations.The results show that the model was able to capture the essential features of these path variations.We used one simulation of the model as the reference state and investigated the effects of errors in model parameters on the prediction of the transition to the Kuroshio large meander (KLM) state using the conditional nonlinear optimal parameter perturbation (CNOP-P) method.Because of their relatively large uncertainties,three model parameters were considcred:the interfacial friction coefficient,the wind-stress amplitude,and the lateral friction coefficient.We determined the CNOP-Ps optimized for each of these three parameters independently,and we optimized all three parameters simultaneously using the Spectral Projected Gradient 2 (SPG2) algorithm.Similarly,the impacts caused by errors in initial conditions were examined using the conditional nonlinear optimal initial perturbation (CNOP-I) method.Both the CNOP-I and CNOP-Ps can result in significant prediction errors of the KLM over a lead time of 240 days.But the prediction error caused by CNOP-I is greater than that caused by CNOP-P.The results of this study indicate not only that initial condition errors have greater effects on the prediction of the KLM than errors in model parameters but also that the latter cannot be ignored.Hence,to enhance the forecast skill of the KLM in this model,the initial conditions should first be improved,the model parameters should use the best possible estimates.

  2. The European ASAMPSA_E project : towards guidance to model the impact of high amplitude natural hazards in the probabilistic safety assessment of nuclear power plants. Information on the project progress and needs from the geosciences.

    Science.gov (United States)

    Raimond, Emmanuel; Decker, Kurt; Guigueno, Yves; Klug, Joakim; Loeffler, Horst

    2015-04-01

    The Fukushima nuclear accident in Japan resulted from the combination of two correlated extreme external events (earthquake and tsunami). The consequences, in particular flooding, went beyond what was considered in the initial engineering design design of nuclear power plants (NPPs). Such situations can in theory be identified using probabilistic safety assessment (PSA) methodology. PSA results may then lead industry (system suppliers and utilities) or Safety Authorities to take appropriate decisions to reinforce the defence-in-depth of the NPP for low probability event but high amplitude consequences. In reality, the development of such PSA remains a challenging task. Definitions of the design basis of NPPs, for example, require data on events with occurrence probabilities not higher than 10-4 per year. Today, even lower probabilities, down to 10-8, are expected and typically used for probabilistic safety analyses (PSA) of NPPs and the examination of so-called design extension conditions. Modelling the combinations of natural or man-made hazards that can affect a NPP and affecting some meaningful probability of occurrence seems to be difficult. The European project ASAMPSAE (www.asampsa.eu) gathers more than 30 organizations (industry, research, safety control) from Europe, US and Japan and aims at identifying some meaningful practices to extend the scope and the quality of the existing probabilistic safety analysis developed for nuclear power plants. It offers a framework to discuss, at a technical level, how "extended PSA" can be developed efficiently and be used to verify if the robustness of Nuclear Power Plants (NPPs) in their environment is sufficient. The paper will present the objectives of this project, some first lessons and introduce which type of guidance is being developed. It will explain the need of expertise from geosciences to support the nuclear safety assessment in the different area (seismotectonic, hydrological, meteorological and biological

  3. High precision terrestrial laser scanning : measuring the individual impact of floods and landslides on meandering bedrock river dynamics (Rangitikei river, New-Zealand)

    Science.gov (United States)

    Lague, D.; Bonnet, S.; Brodu, N.; Davies, T.; Leroux, J.

    2012-04-01

    Actively incising and meandering bedrock rivers are an ubiquitous feature of mountain belts, but the mechanisms leading to their formation and evolution are still poorly understood. Part of the problem lies in our limited ability to quantify in situ the mechanisms governing the dynamics of straight bedrock rivers (tool-cover effects, stochastic sediment supply and discharge effects, roughness effects,...). But the rapid and spatially variable rates of bank erosion in meanders also lead to potentially more complex hillslope-channel interactions than in straight river. Terrestrial laser scanner has the potential to shed new light on these interactions and to capture over large surfaces the impact of individual flood and landsliding events. Given the small changes of surface position that must be detected for even the largest rates of bedrock erosion (~ 5-10 mm/yr) and the 3D geometrical complexity of bedrock meanders, specific survey approaches and post-processing algorithms must be developed. To this end, we started to perform repeated Terrestrial Laser Scanner (TLS) surveys of actively incising meanders in the Rangitikei river (New-Zealand) in 2009. The Rangitikei river is incising weakly consolidated mudstone at an average rate of 5 mm/yr since 15 kyr and has developed a very sinuous meandering pattern with several cut-off bedrock meanders. Lateral undercutting of 100 m high cliffs generates failures of up to hundred of meters. Alluvial material consists of coarse resistant material (D50 ~20 cm) sourced from upstream, and large boulders locally derived from rockfalls. Exposed bedrock is rare on the bed but shows that abrasion, weathering by wetting-drying cycles and plucking are important incision mechanisms. Six TLS surveys were performed at bi-monthly to yearly intervals with a Leica Scanstation 2 in 5 reaches of variable planform curvature. Survey length varies from 300 m to 1200 m and point spacing from ~ 5 mm to 5 cm. Point clouds were co-registered between

  4. Faulted terrace riser position with respect to meanders constrains late Quaternary slip history of the Honey Lake fault, NE California

    Science.gov (United States)

    Gold, R. D.

    2016-12-01

    Faulted terrace risers are prevalent semi-linear features commonly used to constrain Quaternary slip rates along strike-slip faults. Terrace risers are difficult to date directly and therefore the bracketing upper and lower terrace surfaces commonly are used to constrain their ages. However, if there is a significant difference in the age of the upper and lower terrace surfaces, then large uncertainties in slip rate result. Some investigators try to reduce uncertainties by arguing that either the upper- or lower-terrace age closely approximates the age of a terrace riser. To evaluate where this approach is valid, we use 0.25-m airborne lidar data to analyze three sites where terrace risers are laterally offset by the right-lateral Honey Lake fault in NE California. The terrace risers are bracketed by the same sub-horizontal surfaces: an upper surface defined by the bed of abandoned Lake Lahontan having an age of 15.8 ka and a lower fluvial terrace abandoned after 4.7 ka. We estimate a >4x difference in the amount of lateral offset recorded by the risers, ranging from 7 to 30 m. The amount of offset appears to correspond to the riser position relative to modern stream meanders: smaller offsets are in cutbank locations and the largest offset is in the point-bar location. At face value, the results yield slip rates of 0.5 to 6.4 mm/yr. However, in detail, the largest lateral displacement ( 30 m) places a minimum bound on slip rate of 2 mm/yr since 15.8 ka and the smallest displacement ( 7 m) places a maximum bound on slip rate of 1.5 mm/yr since 4.7 ka. This investigation highlights the challenge of correctly determining whether an upper or lower terrace best approximates the age of a faulted terrace riser. To reduce uncertainties, we advocate considering the terrace riser position in the stream system and characterizing numerous faulted and dated landforms.

  5. The meandering Gulf Stream as seen by the Geosat altimeter - Surface transport, position, and velocity variance from 73 deg to 46 deg W

    Science.gov (United States)

    Kelly, Kathryn A.

    1991-01-01

    Results are presented of an analysis of the surface geostrophic velocity field for the Gulf Stream region for the position, structure, and surface transport of the Gulf Stream for 2.5 yr of the Geosat altimeter Exact Repeat Mission. Synthetic data using a Gaussian velocity profile were generated and fit to the sea surface residual heights to create a synthetic mean sea surface height field and profiles of absolute geostrophic currents. An analysis of the model parameters and the actual geostrophic velocity profiles revealed two different flow regimes for the Gulf Stream connected by a narrow transition region coincident with the New England Seamount Chain. The upstream region was found to exhibit relatively straight Gulf Stream paths, long Eulerian time scales, and eastward propagating meanders. The downstream region had more large meanders, no consistent propagation direction, and shorter Eulerian time scales. A 25-percent reduction in surface transport occurred in the transition region, with a corresponding reduction in current speed and no change in Gulf Stream width.

  6. Tightening the River Meander-Belt: Application of a Topographic Erodible Corridor Concept Using DEM Raster Analysis. A Case Study of Highland Creek, Ontario.

    Science.gov (United States)

    Phillips, R. T.

    2009-05-01

    Planimetric river hazard assessments, typically delineated as meander-belts, are complicated in southern Ontario by rivers which are incised into thick glacial sediments. Active and relic floodplain surfaces are topographically diverse, with river terraces commonly observed in the valleys due to deglacial and Holocene incision. Consequently, channels are often in contact with a mixed boundary of alluvial and glaciogenic sediments. Accepted meander-belt delineation procedures and protocols vary between intra-national and international jurisdictions; however, a focus on planimetric mapping and historical techniques is common place. In the southern Ontario context, this type of reach-scale river hazard assessment is important for protection of upland property, erosion risks to valley bottom infrastructure, and delineation of new development limits. Given the ecological and public safety benefits, there is growing acceptance and expectation that river bank erosion processes should be preserved within an erodible corridor, with a decreased emphasis on channel intervention and engineering approaches where possible. However, the use of planimetric meander- belt delineation techniques for incised valley settings frequently meets both practical and conceptual challenges. This study explores the potential for a Topographic Erodible Corridor Concept (TECC) as an improved representation of river evolution compared to the traditional planimetric techniques, particularly in previously glaciated regions. Such a concept would account for differences in erodible volumes of sediment associated with topographic variations within incised river valleys. Application of this concept is investigated using raster analysis of a high resolution digital elevation model (DEM), within widely available GIS software. Initial results from a case study on Highland Creek (Ontario) confirm that the corridor alignment and diverse topography of the incised valley morphology are well represented by a

  7. Development processes of chute cutoffs on meandering rivers%弯曲河流斜槽裁弯模式与发育过程

    Institute of Scientific and Technical Information of China (English)

    李志威; 王兆印; 赵娜; 余国安

    2013-01-01

    Chute cutoff is one form of natural cutoffs on meandering rivers. This paper studies the patterns and development processes of chute cutoffs through field investigations and statistical analyses using remote sensing images. The natural chute cutoffs are divided into shoal-cutting pattern, ditch-scouring pattern and embayment-eroding pattern. The shoal-cutting pattern is caused by the direction of main flow turning to the shoal of convex bank during flood, which results in overbank flow on the shoal and a new chute on shoal. Such a cutoff is found on 67 meanders among the examined rivers. The average ratio of the bend curvature radius is about 3 times of the average stream width and the average angle of dividing flow is about 55. The ditch-scouring pattern is the result of pre-flood overflows forming several ditches, and one of the ditches is scoured, enlarged and deepened, and finally formed the cutoff. In the embayment-eroding pattern, the mainstream flow erodes the inside bank of river bends and forms an embayment, and then the flood erosion results in the downstream extension of the embayment until cutoff the meander.%结合遥感影像、野外调查和形态统计,深入分析斜槽裁弯现象,将其划分为切滩冲刷、串沟冲刷和主流顶冲3种模式.切滩模式发生于洪水期间主流水流动力轴线偏向凸滩后,形成漫流水流冲刷,极可能在边滩形成新的斜槽.切滩裁弯的形态统计表明,弯道曲率半径与平均河宽之比约2.92,分流角约54.8°.串沟模式是前期洪水漫过河湾内侧洪泛平原,漫滩水流冲刷形成若干串沟,后续洪水沿串沟继续冲刷,串沟逐步横向展宽和向下游侵蚀,直至形成新的河槽.主流顶冲模式是水流顶冲河湾内侧河岸,形成湾状缺口,后续洪水持续顶冲湾状缺口,直至上下游水流贯通,形成斜槽裁弯.

  8. Coplanar-waveguide-based silicon Mach-Zehnder modulator using a meandering optical waveguide and alternating-side PN junction loading.

    Science.gov (United States)

    Dong, Po; Sinsky, Jeffrey H; Gui, Chengcheng

    2016-09-15

    We demonstrate a silicon Mach-Zehnder modulator with a coplanar waveguide transmission-line electrode structure using a meandering optical waveguide and alternating-side PN junction loading of the electrodes, which helps suppress the signal distortion caused by the parasitic slot-line mode and improves the electro-optic (EO) bandwidth. The silicon MZM exhibits a π-phase-shift voltage (Vπ) of 4.5 V with an EO 3 dB bandwidth of ∼20  GHz for a 5 mm long phase shifter. This achieved Vπ is among the lowest for silicon-only modulators with a bandwidth of more than 20 GHz.

  9. Polychlorinated Biphenyls in suspended-sediment samples from outfalls to Meandering Road Creek at Air Force Plant 4, Fort Worth, Texas, 2003-08

    Science.gov (United States)

    Braun, Christopher L.; Wilson, Jennifer T.

    2010-01-01

    Meandering Road Creek is an intermittent stream and tributary to Lake Worth, a reservoir on the West Fork Trinity River on the western edge of Fort Worth, Texas. U.S. Air Force Plant 4 (AFP4) is on the eastern shore of Woods Inlet, an arm of Lake Worth. Meandering Road Creek gains inflow from several stormwater outfalls as it flows across AFP4. Several studies have characterized polychlorinated biphenyls (PCBs) in the water and sediments of Lake Worth and Meandering Road Creek; sources of PCBs are believed to originate primarily from AFP4. Two previous U.S. Geological Survey (USGS) reports documented elevated PCB concentrations in surficial sediment samples from Woods Inlet relative to concentrations in surficial sediment samples from other parts of Lake Worth. The second of these two previous reports also identified some of the sources of PCBs to Lake Worth. These reports were followed by a third USGS report that documented the extent of PCB contamination in Meandering Road Creek and Woods Inlet and identified runoff from outfalls 4 and 5 at AFP4 as prominent sources of these PCBs. This report describes the results of a fourth study by the USGS, in cooperation with the Lockheed Martin Corporation, to investigate PCBs in suspended-sediment samples in storm runoff from outfalls 4 and 5 at AFP4 following the implementation of engineering controls designed to potentially alleviate PCB contamination in the drainage areas of these outfalls. Suspended-sediment samples collected from outfalls 4 and 5 during storms on March 2 and November 10, 2008, were analyzed for selected PCBs. Sums of concentrations of 18 reported PCB congeners (Sigma PCBc) in suspended-sediment samples collected before and after implementation of engineering controls are compared. At both outfalls, the Sigma PCBc before engineering controls was higher than the Sigma PCBc after engineering controls. The Sigma PCBc in suspended-sediment samples collected at AFP4 before and after implementation of

  10. Response of lateral channel dynamics of a lowland meandering river to engineering-derived adjustments - an example of the Morava River (Czech Republic)

    Science.gov (United States)

    Ondruch, Jakub; Mácka, Zdenek

    2015-11-01

    Freely meandering (quasi)natural reaches of lowland rivers represent a rare phenomenon in Central Europe. Increasing attention is currently being paid to the dynamics of quasi-natural (artificially influenced) meandering rivers as this attention represents the basic prerequisite for the development of appropriate restoration strategies on regulated rivers. This study focused on a 5.5 km long reach of the Morava River in the Strážnické Pomoraví region, Czech Republic that is characterised by quasi-natural evolution after substantial engineering adjustments were made in the first decades of the twentieth century. Based on Geographic Information Systems (GIS) analysis of aerial photographs, the spatio-temporal dynamics of bank erosion and accretion rates were quantitatively described and variables that control channel migration rates were identified. High rates of lateral shifts were localised in high sinuosity segments (sinuosity 1.17-2.37), whereas segments with very low rates were straight or formed into slightly curved bends (sinuosity 1.05-1.18). As a key factor, engineering works that influenced local river bed slope and induced a dramatic increase in bank erosion rates were identified. River engineering works induced a dramatic increase in bank erosion rate (2.19 m/year for 1938-53 and 1.47 m/year for 1953-63). An interval of approximately 25 years was needed before the erosion rates dropped back to values documented before river regulation (0.35-1.09 m/year for 1841-1938). Other important controlling variables included radius of curvature, frequency and magnitude of floods and, locally, river bank material properties and floodplain land cover.

  11. Paleohydrology of meandering systems: a new approach for the reconstruction of ancient drainage areas and the quantification of the controlling factors

    Science.gov (United States)

    Held, A.; Cojan, I.

    2009-12-01

    In meandering system fluvial sedimentology, studying infill geometries and sedimentary structures of channelized sandstone bodies, gives information about the sedimentary dynamic and the depositional environment. Associated with such a sedimentary approach, paleohydrology enables the reconstruction of hydrological parameters such as discharge, drainage area or stream length. Although fluvial systems are known to be influenced by allogenic and/or autogenic processes, climate or structural evolution were not taken into account in previous paleohydrological studies. Therefore, the present study attempts to develop a new method of paleohydrological reconstitution, based on the geometry of fluvial sandstone bodies and constrained by the controlling factors (climate and tectonic). We selected two meandering systems of the same age, developed under different climatic setting: the first one is located in the Alpine Foreland Basin (SE France) and was associated to a subtropical humid realm; the second one is situated in the Loranca Basin (Central Spain) and was related to subtropical semi-arid conditions. Dealing with the uniformitarianism concept, we developed a new method to determine the paleohydrological parameters of the two different systems. For each of these two climatic setting we have constructed an equivalent modern rivers database taking into account their respective climatic conditions. By defining empirical relations, we translated the point-bar thickness (the only data available in the field) into paleohydrological parameters, such as channel geometry, water discharge and basin geometry. Because fluvial members studied are composed of several channelized sequences; each of them gives a specific drainage area depending on discharge value and climatic coefficient. But assuming a constant basin area all along the river evolution, we can quantify the spatiotemporal impact of the climate on the development of an alluvial system. Furthermore, granulometry

  12. O desenvolvimento meandroso da educação brasileira entre o estado e o mercado The meandering development of Brazilian education between State and market

    Directory of Open Access Journals (Sweden)

    Luiz Antônio Cunha

    2007-10-01

    Full Text Available O artigo questiona a imagem da privatização da educação brasileira como um processo generalizado e contínuo. Defende que a privatização consiste num processo cheio de meandros, que não comporta resposta simples, porque as forças que a determinam ora incentivam o crescimento do setor público, ora do setor privado, ora de ambos. Como sustentação da argumentação, é examinada a legislação federal relativa aos incentivos às instituições privadas nas últimas quatro décadas, assim como as estatísticas de alunos dos três níveis de ensino. O autor chama a atenção para o fato de que o aumento do número de alunos do ensino médio público gera uma nova qualidade, que exige um novo currículo. O artigo conclui que o caráter meandroso dessas fronteiras expressa, de um lado, uma crise de hegemonia no que concerne à natureza do Estado republicano e, de outro, o travamento de uma qualidade de que a educação brasileira carece, qual seja, a da clareza na distinção entre o público e o privado, em sua dimensão institucional e curricular.The present study seeks to question the image of the privatization of Brazilian education, which is presented as a generalized and ongoing process. It argues that this privatization process is full of meanders and does not accept simple answers because it is established by forces that sometimes stimulate the growth of the public sector, sometimes that of the private sector and sometime that of both. To support this argument, it explores both the federal legislation on incentives to private institutions passed these last four decades and the statistics on students in the three levels of education. The author highlights the fact that the increase in the number of secondary public school students generates a new quality that demands a new curriculum. The paper concludes that the meandering character of such frontiers demonstrates, on the one hand, a crisis of hegemony with regard to the nature of the

  13. Morphological responses in a meandering and island-braided reach of the Middle Yangtze River to the Three Gorges Reservoir impoundment

    Institute of Scientific and Technical Information of China (English)

    Dongdong Jia; Xuejun Shao; Xingnong Zhang; Yongjun Lu; Pengfei Hei

    2016-01-01

    Lateral migration is an important form of morphological changes on the Middle Yangtze River (MYR), particularly for the lower Jingjiang reach. The Three Gorges Reservoir (TGR) has substantially reduced sediment supply to the downstream river channels since its impoundment in June 2003. The scientific understanding of how decrease of sediment influences the processes of bank erosion and channel adjustments is complex and limited. In the present paper, the morphological responses in a typical meandering and island-braided river segment of the MYR to the filling of the TGR were investigated by a 3-D morphodynamic model. The potential of the 3-D model has been demonstrated by the observed data. The morphological evolutions in the Shishou bend during the first 12 years of the TGR impound-ment were predicted. The effects of the TGR operation on the planform evolutions in the study reach were analyzed based on the simulated results. Sediment load is decreased by 75%due to the early filling of the TGR. The magnitude of bed degradation with less sediment load due to the TGR operation is increased compared with the pre-dam situation. Qualitatively, the overall planform evolution trends in the Shishou bend after the TGR operation are similar to that without the TGR operation. The magnitude of lateral migration has been increased in some part of the channel bend, where the morphological response of the TGR operation exhibits more lateral migration rather than vertical degradation. Scouring at the bank toe enhances bank failure. Decrease of sediment load and weak bank anti-scour ability as well as the significant helical flow can be responsible for intensified bank erosion in the channel bend.

  14. Continued Development of Meandering Winding Magnetometer (MWM (Register Trademark)) Eddy Current Sensors for the Health Monitoring, Modeling and Damage Detection of Composite Overwrapped Pressure Vessels

    Science.gov (United States)

    Russell, Richard; Wincheski, Russell; Jablonski, David; Washabaugh, Andy; Sheiretov, Yanko; Martin, Christopher; Goldfine, Neil

    2011-01-01

    Composite Overwrapped Pressure Vessels (COPVs) are used in essentially all NASA spacecraft, launch. vehicles and payloads to contain high-pressure fluids for propulsion, life support systems and science experiments. Failure of any COPV either in flight or during ground processing would result in catastrophic damage to the spacecraft or payload, and could lead to loss of life. Therefore, NASA continues to investigate new methods to non-destructively inspect (NDE) COPVs for structural anomalies and to provide a means for in-situ structural health monitoring (SHM) during operational service. Partnering with JENTEK Sensors, engineers at NASA, Kennedy Space Center have successfully conducted a proof-of-concept study to develop Meandering Winding Magnetometer (MWM) eddy current sensors designed to make direct measurements of the stresses of the internal layers of a carbon fiber composite wrapped COPV. During this study three different MWM sensors were tested at three orientations to demonstrate the ability of the technology to measure stresses at various fiber orientations and depths. These results showed good correlation with actual surface strain gage measurements. MWM-Array technology for scanning COPVs can reliably be used to image and detect mechanical damage. To validate this conclusion, several COPVs were scanned to obtain a baseline, and then each COPV was impacted at varying energy levels and then rescanned. The baseline subtracted images were used to demonstrate damage detection. These scans were performed with two different MWM-Arrays. with different geometries for near-surface and deeper penetration imaging at multiple frequencies and in multiple orientations of the linear MWM drive. This presentation will include a review of micromechanical models that relate measured sensor responses to composite material constituent properties, validated by the proof of concept study, as the basis for SHM and NDE data analysis as well as potential improvements including

  15. Development of Meandering Winding Magnetometer (MWM (Register Trademark)) Eddy Current Sensors for the Health Monitoring, Modeling and Damage Detection of High Temperature Composite Materials

    Science.gov (United States)

    Russell, Richard; Washabaugh, Andy; Sheiretov, Yanko; Martin, Christopher; Goldfine, Neil

    2011-01-01

    The increased use of high-temperature composite materials in modern and next generation aircraft and spacecraft have led to the need for improved nondestructive evaluation and health monitoring techniques. Such technologies are desirable to improve quality control, damage detection, stress evaluation and temperature measurement capabilities. Novel eddy current sensors and sensor arrays, such as Meandering Winding Magnetometers (MWMs) have provided alternate or complimentary techniques to ultrasound and thermography for both nondestructive evaluation (NDE) and structural health monitoring (SHM). This includes imaging of composite material quality, damage detection and .the monitoring of fiber temperatures and multidirectional stresses. Historically, implementation of MWM technology for the inspection of the Space Shuttle Orbiter Reinforced Carbon-Carbon Composite (RCC) leading edge panels was developed by JENTEK Sensors and was subsequently transitioned by NASA as an operational pre and post flight in-situ inspection at the Kennedy Space Center. A manual scanner, which conformed'automatically to the curvature of the RCC panels was developed and used as a secondary technique if a defect was found during an infrared thermography screening, During a recent proof of concept study on composite overwrapped pressure vessels (COPV's), three different MWM sensors were tested at three orientations to demonstrate the ability of the technology to measure stresses at various fiber orientations and depths. These results showed excellent correlation with actual surface strain gage measurements. Recent advancements of this technology have been made applying MWM sensor technology for scanning COPVs for mechanical damage. This presentation will outline the recent advance in the MWM.technology and the development of MWM techniques for NDE and SHM of carbon wraped composite overwrapped pressure vessels (COPVs) including the measurement of internal stresses via a surface mounted sensor

  16. Radial convection of finite ion temperature, high amplitude plasma blobs

    DEFF Research Database (Denmark)

    Wiesenberger, M.; Madsen, Jens; Kendl, Alexander

    2014-01-01

    We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line...... with conditions found in tokamak scrape-off-layers (SOL) regions. Varying the ion temperature, the initial blob width, and the initial amplitude, we found an FLR dominated regime where the blob behavior is significantly different from what is predicted by cold-ion models. The transition to this regime is very...

  17. High-amplitude, ultrashort strain solitons in solids

    NARCIS (Netherlands)

    Muskens, O.L.

    2004-01-01

    In recent years, pressure pulses of very short (picosecond) time duration have found wide application as a diagnostic tool in the semiconductor industry and in fundamental condensed matter research. Next to their application in the studies of nanometer-sized structures, propagation of these short ac

  18. High Amplitude (delta)-Scutis in the Large Magellanic Cloud

    National Research Council Canada - National Science Library

    Garg, A; Cook, K H; Nikolaev, S; Huber, M E; Rest, A; Becker, A C; Challis, P; Clocchiatti, A; Miknaitis, G; Minniti, D; Morelli, L; Olsen, K; Prieto, J L; Suntzeff, N B; Welch, D L; Wood-Vasey, W M

    2010-01-01

    ... (LMC) by the SuperMACHO survey (Rest et al. 2005). Frequency analyses of these candidates reveal that several are multimode pulsators, including 119 whose largest amplitude of pulsation is in the fundamental (F...

  19. Radial convection of finite ion temperature, high amplitude plasma blobs

    CERN Document Server

    Wiesenberger, M; Kendl, A

    2014-01-01

    We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line with conditions found in tokamak scrape-off-layers (SOL) regions. Varying the ion temperature, the initial blob width and the initial amplitude, we found an FLR dominated regime where the blob behavior is significantly different from what is predicted by cold-ion models. The transition to this regime is very well described by the ratio of the ion gyroradius to the characteristic gradient scale length of the blob. We compare the global gyrofluid model with a partly linearized local model. For low ion temperatures we find that simulations of the global model show more coherent blobs with an increased cross-field transport compared to blobs simulated with the local model. The maximal blob amplitude is significantly higher in ...

  20. Effects of Liquid Second Viscosity in High-Amplitude Sonoluminescence

    Institute of Scientific and Technical Information of China (English)

    Ahmad Moshaii; Rasool Sadighi-Bonabi; Mohammad Taeibi-Rahni; Mehdi Daemi

    2004-01-01

    @@ The well-known Rayleigh-Plesset (RP) equation is the base of nearly all hydrodynamical descriptions of the sonoluminescence phenomenon. A major deficiency of this equation is that it accounts for viscosity of an incompressible liquid and compressibility, separately. By removing this approximation, we have modified the RP equation, considering effects of liquid second viscosity. This modification exhibits its importance at the end of an intense collapse, so that the new model predicts the appearance of a new picosecond bouncing during highamplitude sonoluminescence radiation. This new bouncing produces very sharp (sub-picosecond) peaks on the top of the sonoluminescence pulse. These new behaviours are more remarkable for higher driving pressures and lower ambient temperatures.

  1. High-amplitude, ultrashort strain solitons in solids

    NARCIS (Netherlands)

    Muskens, O.L.

    2004-01-01

    In recent years, pressure pulses of very short (picosecond) time duration have found wide application as a diagnostic tool in the semiconductor industry and in fundamental condensed matter research. Next to their application in the studies of nanometer-sized structures, propagation of these short

  2. Thermal Mechanisms for High Amplitude Aerodynamic Flow Control (YIP 2012)

    Science.gov (United States)

    2016-04-15

    employed to generate shear layer profiles. Two access holes are drilled in the tunnel sidewalls to provide a path for laser beam. The holes were...observed for the ns- DBD plasma case. The laser -induced wave strength at short delay can exceed four times that of the ns-DBD case. The laser wave...energy deposition for mixing layer excitation. Figure 52 shows the response of the mixing layer to Nd:YAG laser energy deposition. The time trace

  3. River response to climate and sea level changes during the Late Saalian/Early Eemian in northern Poland – a case study of meandering river deposits in the Chłapowo cliff section

    Directory of Open Access Journals (Sweden)

    Moskalewicz Damian

    2016-03-01

    Full Text Available Fluvial sediments in the Chłapowo cliff section were studied in order to reconstruct their palaeoflow conditions and stratigraphical position. Lithofacies, textural and palaeohydraulic analyses as well as luminescence dating were performed so as to achieve the aim of study. Sedimentary successions were identified as a record of point bar cycles. The fluvial environment probably functioned during the latest Saalian, shortly after the retreat of the Scandinavian Ice Sheet. Discharge outflow was directed to the northwest. The river used the older fluvioglacial valley and probably was directly connected to the Eem Sea. Good preservation and strong aggradation of point-bar cycles were related to a rapid relative base level rise. The meandering river sediments recognised showed responses to climate and sea level changes as illustrated by stratigraphical, morphological and sedimentological features of the strata described. The present study also revealed several insights into proper interpretation of meandering fluvial successions, in which the most important were: specific lithofacies assemblage of GSt (St, Sp → Sl → SFrc → Fm (SFr and related architectural elements: channel/sandy bedforms CH/SB → lateral accretion deposits LA → floodplain fines with crevasse splays FF (CS; upward-fining grain size and decreasing content of denser heavy minerals; estimated low-energy flow regime with a mean depth of 1.6–3.3 m, a Froude number of 0.2–0.4 and a sinuosity of 1.5.

  4. Testing river surveying techniques in tidal environments: example from an actively meandering channel surveyed with TLS (Mont Saint-Michel bay, France)

    Science.gov (United States)

    Leroux, J.; Lague, D.

    2013-12-01

    factor 2 during summer/autumn spring tides at the peak of pioneer vegetation development. Bank erosion and channel dynamics show a marked difference for tides reaching the salt marsh elevation. For tides below marsh elevation, bank erosion is negligible and the channel is systematically aggrading at a rate proportional to HWL. For tides flooding the marsh, mean bank erosion increases linearly with HWL and the channel shifts to erosion for over-marsh tides. Using flow velocity and SSC data we show that sedimentation on the inner bar results from the penetration of the turbid flood onto the inner bar. Spatial variability in sedimentation results from local interactions between flow and vegetation. On the contrary, bank erosion is dominated by the very large ebb peak velocity developing during spring tides. The very non-linear sensitivity to HWL of bank erosion and channel erosion means that the rate of evolution is largely controlled by the largest tides of the year. This in turn yields very large annual fluctuations in the rates of meander evolution. These results demonstrate that mega-tidal environment can offer an alternative setting to test new survey techniques aimed at river monitoring and can shed light in the elementary processes governing biogeomorphological interactions.

  5. 黄河源区典型弯曲河流的几何形态特征%Planform geometry characteristics of typical meandering rivers in Yellow River Source

    Institute of Scientific and Technical Information of China (English)

    李志威; 王兆印; 李艳富; 刘乐

    2012-01-01

    The Bailie and Heihe rivers are tributaries in the Yellow River source region in the north-eastern part of the Qinghai-Tibet Plateau. The rivers are meandering with extremely high sinuosity and numerous oxbow lakes. Digital Elevation Model and Google Earth satellite images are used for analyzing the characteristics of the rivers, meanders and oxbow lakes. River networks and longitudinal bed profiles of the Baihe and Heihe rivers are extracted by using GIS model. Channel width, sinuosity, valley width and number of oxbow lakes are calculated with AutoCAD software. Average sinuosity of the Heihe River is 2. 46, which is much greater than that of the Baihe River (1. 68). It is found that the sinuosity of the Heihe river is greater than the Baihe River and the main causes for the big difference are their different average flow discharges and average channel gradients. The Heihe River has much higher density of oxbow lakes than the Baihe River. The density of oxbow lakes of the Heihe River is more uniform along the course which keeps a higher frequency of cutoffs. The density of oxbow lakes reduces along the course of the Baihe River because the channel width and average flow discharge increase along the course.%黄河源区支流白河和黑河位于青藏高原东北部若尔盖盆地的东部,河道蜿蜒曲折,是典型弯曲型河流,研究其弯曲河道的一般形态规律,有利于认识青藏高原弯曲河流的发育条件和形态特征.基于遥感图像、DEM和野外调查,利用ArcGIS提取了白河和黑河的河网,计算了沿程的纵比降,并测算了河道宽度、弯曲度、河谷宽度和牛轭湖数量.白河和黑河的统计河段平均弯曲度分别为1.68和2.46,黑河平均弯曲度大于白河的主要原因是黑河的多年平均流量和河道纵比降均小于白河.白河单位河长的牛轭湖数量沿程由多变少,黑河单位河长的牛轭湖数量沿程趋于均匀,且牛轭湖数量多于白河,说明黑河沿程保持更高的自然裁弯频率.

  6. The Wavelet ToolKat: A set of tools for the analysis of series through wavelet transforms. Application to the channel curvature and the slope control of three free meandering rivers in the Amazon basin.

    Science.gov (United States)

    Vaudor, Lise; Piegay, Herve; Wawrzyniak, Vincent; Spitoni, Marie

    2016-04-01

    The form and functioning of a geomorphic system result from processes operating at various spatial and temporal scales. Longitudinal channel characteristics thus exhibit complex patterns which vary according to the scale of study, might be periodic or segmented, and are generally blurred by noise. Describing the intricate, multiscale structure of such signals, and identifying at which scales the patterns are dominant and over which sub-reach, could help determine at which scales they should be investigated, and provide insights into the main controlling factors. Wavelet transforms aim at describing data at multiple scales (either in time or space), and are now exploited in geophysics for the analysis of nonstationary series of data. They provide a consistent, non-arbitrary, and multiscale description of a signal's variations and help explore potential causalities. Nevertheless, their use in fluvial geomorphology, notably to study longitudinal patterns, is hindered by a lack of user-friendly tools to help understand, implement, and interpret them. We have developed a free application, The Wavelet ToolKat, designed to facilitate the use of wavelet transforms on temporal or spatial series. We illustrate its usefulness describing longitudinal channel curvature and slope of three freely meandering rivers in the Amazon basin (the Purus, Juruá and Madre de Dios rivers), using topographic data generated from NASA's Shuttle Radar Topography Mission (SRTM) in 2000. Three types of wavelet transforms are used, with different purposes. Continuous Wavelet Transforms are used to identify in a non-arbitrary way the dominant scales and locations at which channel curvature and slope vary. Cross-wavelet transforms, and wavelet coherence and phase are used to identify scales and locations exhibiting significant channel curvature and slope co-variations. Maximal Overlap Discrete Wavelet Transforms decompose data into their variations at a series of scales and are used to provide

  7. Re-Meandering of Lowland Streams

    DEFF Research Database (Denmark)

    Pedersen, Morten Lauge; Kristensen, Klaus Kevin; Friberg, Nikolai

    2014-01-01

    We evaluated the restoration of physical habitats and its influence on macroinvertebrate community structure in 18 Danish lowland streams comprising six restored streams, six streams with little physical alteration and six channelized streams. We hypothesized that physical habitats...... and macroinvertebrate communities of restored streams would resemble those of natural streams, while those of the channelized streams would differ from both restored and near-natural streams. Physical habitats were surveyed for substrate composition, depth, width and current velocity. Macroinvertebrates were sampled...... along 100 m reaches in each stream, in edge habitats and in riffle/run habitats located in the center of the stream. Restoration significantly altered the physical conditions and affected the interactions between stream habitat heterogeneity and macroinvertebrate diversity. The substrate in the restored...

  8. Analytical modelling and calculation of impedance and pulsed magnetic field for rectangular meander coil based on second order potential%基于二阶矢量位的矩形截面回折线圈阻抗和脉冲磁场的解析建模与计算

    Institute of Scientific and Technical Information of China (English)

    郝宽胜; 黄松岭; 赵伟; 王坤

    2011-01-01

    Meander coil is an important kind of coil configuration used in eddy current testing and electromagnetic acoustic testing. Owing to lack of analytical calculation formulas of impedance and magnetic field for meander coil, the analytical modeling is performed and a method of calculating pulsed response is presented. In terms of the general model for eddy current testing and electromagnetic acoustic testing, the calculation of impedance and pulsed magnetic field is transformed into the superposition of impedance and pulsed magnetic field of single rectangular coils. Based on the second order vector potential and the time harmonic magnetic field equations, the scalar potential analytical expressions of the meander coil are derived. Then the analytical expressions of magnetic flux in all solution area and eddy current in the specimen are obtained. By calculating the induction electric potential and the impedance change, the impedance analytical expression of the rectangular meander coil is derived. An FFT-IFFT method is used to calculate the time domain response to pulsed magnetic field. A model with an 8-meander double-layer double-bundle coil above an aluminium plate is used in calculation, and the results are in good agreement with the experimental result and the TSFEM calculation result, which verifies the analytical model and the accuracy of the calculation method. The analytical calculation largely shortens the calculation time compared with that by TSFEM method.%本文基于二阶矢量位建立了回折线圈的阻抗和磁场计算的解析模型,并提出了计算磁场脉冲响应的方法.根据回折线圈用于涡流检测和电磁超声检测时的通用模型,将回折线圈的阻抗和磁场计算问题转化为多个单匝矩形线圈阻抗和磁场的叠加问题.基于二阶矢量位和时谐电磁场方程,推导了回折线圈的频域标势表达式;利用标势与矢量磁位和磁通密度间的关系,推导了计算区域的磁

  9. Polychlorinated biphenyls in aquatic invertebrates and fish and observations about nitrogen and carbon isotope composition in relation to trophic structure and bioaccumulation patterns, Lake Worth and Meandering Road Creek, Fort Worth, Texas, 2007-08

    Science.gov (United States)

    Moring, J. Bruce

    2010-01-01

    During 2007-08 the U.S. Geological Survey, in cooperation with the U.S. Air Force, evaluated the concentration of polychlorinated biphenyls (PCBs) in aquatic invertebrates and fish from one site in the main body of Lake Worth, two sites in a small inlet in Lake Worth (upper and lower Woods Inlet), and one site in Meandering Road Creek in Fort Worth, Texas. The four sites sampled during 2007-08 were located at or near sites where surficial bed-sediment samples had been collected and analyzed for PCBs during previous U.S. Geological Survey studies so that PCB concentrations in aquatic invertebrates and fish and PCB concentrations in surficial bed-sediment samples could be compared. Stable nitrogen and carbon isotopes were used to help assess differences in the amount of these isotopes by species and sampling location. The sum of 15 PCB-congener concentrations was highest for aquatic invertebrates and fish from the upper Woods Inlet site and lowest for the same aquatic invertebrates and fish from Lake Worth site, where PCBs historically had not been detected in lake bed sediment. An increase in the ratio of the heavier nitrogen-15 (15N) isotope to the lighter nitrogen-14 (14N) isotope, referred to as enrichment of 15N, was highest in largemouth bass (representing the highest trophic level sampled) at all sites and lowest for true midge larvae inhabiting surficial bed sediment in the lake (representing the lowest trophic level sampled). Enrichment of 15N was less variable in largemouth bass and other fish from the highest trophic level compared with shorter lived, primary consumer invertebrates from lower trophic levels, such as true midge larvae, mayfly nymphs, and zooplankton. The delta carbon-13 (delta13C) values measured in true midge larvae collected at the Lake Worth and upper and lower Woods Inlet sites were more negative compared with the delta13C values measured for all other taxa, indicating true midge larvae were more depleted of carbon-13 (13C) compared

  10. Correlation between river slope and meandering variability (obtained by DGPS data) and morphotectonics for two Andean tributaries of the Amazon river: the case of Beni (Bolivia) and Napo (Ecuador-Peru) rivers.

    Science.gov (United States)

    Bourrel, L.; Darrozes, J.; Guyot, J.; Christophoul, F.; Bondoux, F.

    2007-05-01

    The Beni river drains a catchment area of 282 000 km2 of which 40 percent are located in the Cordillera of the Bolivian and Peruvian Andes, and the rest in the Amazonian plain : the studied reaches runs from Guanay (Andean Piedmont) to Riberalta (junction with Madre de Dios river) that represents a distance by the river of 1055 km. The Napo river starts in the Ecuadorian Andes and leaves Ecuador in Nuevo Rocafuerte (27 400 km2) and enters in Peru until its junction with the Amazon river : the studied section runs from Misahualli (Andean Piedmont) to this junction, that represents a distance by the river of 995 km. The GPS data were acquired using a mobile GPS embarked on a boat and 4 fixed bases located along the Beni river, 6 along the Napo river and the two rivers profile calculated from post-treated differential GPS solutions. For the Beni river, two sectors were identified: - the upstream sector (~230 km) between Guanay (414 m) and 50 km downstream Rurrenabaque (245 m) is located in Andean Piedmont, which consists in a series of thrusts associated with anticlines and synclines (the subandean zone), and presents slope values range between 135 cm/km and 10 cm/km and an average index of sinuosity (IS) of 1.29, - the downstream sector (~ 820 km) which runs in Amazonian plain (until Riberalta -165 m-), is characterized by an average slope of 8 cm/km and an average IS of 2.06 (this sector is much more homogeneous and the Beni river shows a meandering channel). For the Napo River, three sectors were identified: - the first sector (~140 km) between Misahualli (401 m) and Coca (265 m), is located in Andean Piedmont (subandean zone) and presents slope values range between 170 cm/km and 30 cm/km and an average IS of 1.6, - the second sector (~250 km) between Coca (when the Napo river enters in the Amazonian plain) and Nuevo Rocafuerte (190 m), presents slope values range between 30 cm/km and 20 cm/km and an average IS of 1.2, and a convex-up shape profile corresponding to

  11. High amplitude vortex-induced pulsations in a gas transport system

    NARCIS (Netherlands)

    Kriesels, P.C.; Peters, M.C.A.M.; Hirschberg, A.; Wijnands, A.P.J.; Iafrati, A.; Riccardi, G.; Piva, R.; Bruggeman, J.C.

    1995-01-01

    High Reynolds number, low Mach number gas flows in pipe systems with closed side branches exhibit spectacular low frequency self-sustained pulsations driven by periodic vortex shedding at specific values of the Strouhal number. A detailed study is presented of the behaviour of the flow in a system w

  12. Discovery of a Long-Lived, High Amplitude Dusty Infrared Transient

    CERN Document Server

    Britt, C T; Green, J D; Jonker, P G; Hynes, R I; Torres, M A P; Strader, J; Chomiuk, L; Salinas, R; Lucas, P; Pena, C Contreras; Kurtev, R; Heinke, C; Smith, L; Wright, N J; Johnson, C; Steeghs, D; Nelemans, G

    2016-01-01

    We report the detection of an infrared selected transient which has lasted at least 5 years, first identified by a large mid-infrared and optical outburst from a faint X-ray source detected with the Chandra X-ray Observatory. In this paper we rule out several scenarios for the cause of this outburst, including a classical nova, a luminous red nova, AGN flaring, a stellar merger, and intermediate luminosity optical transients, and interpret this transient as the result of a Young Stellar Object (YSO) of at least solar mass accreting material from the remains of the dusty envelope from which it formed, in isolation from either a dense complex of cold gas or massive star formation. This object does not fit neatly into other existing categories of large outbursts of YSOs (FU Orionis types) which may be a result of the object's mass, age, and environment. It is also possible that this object is a new type of transient unrelated to YSOs.

  13. High-amplitude electrical stimulation can reduce elicited neuronal activity in visual prosthesis

    Science.gov (United States)

    Barriga-Rivera, Alejandro; Guo, Tianruo; Yang, Chih-Yu; Abed, Amr Al; Dokos, Socrates; Lovell, Nigel H.; Morley, John W.; Suaning, Gregg J.

    2017-01-01

    Retinal electrostimulation is promising a successful therapy to restore functional vision. However, a narrow stimulating current range exists between retinal neuron excitation and inhibition which may lead to misperformance of visual prostheses. As the conveyance of representation of complex visual scenes may require neighbouring electrodes to be activated simultaneously, electric field summation may contribute to reach this inhibitory threshold. This study used three approaches to assess the implications of relatively high stimulating conditions in visual prostheses: (1) in vivo, using a suprachoroidal prosthesis implanted in a feline model, (2) in vitro through electrostimulation of murine retinal preparations, and (3) in silico by computing the response of a population of retinal ganglion cells. Inhibitory stimulating conditions led to diminished cortical activity in the cat. Stimulus-response relationships showed non-monotonic profiles to increasing stimulating current. This was observed in vitro and in silico as the combined response of groups of neurons (close to the stimulating electrode) being inhibited at certain stimulating amplitudes, whilst other groups (far from the stimulating electrode) being recruited. These findings may explain the halo-like phosphene shapes reported in clinical trials and suggest that simultaneous stimulation in retinal prostheses is limited by the inhibitory threshold of the retinal ganglion cells. PMID:28209965

  14. Acoustic minor losses in high amplitude resonators with single-sided junctions

    Science.gov (United States)

    Doller, Andrew J.

    Steady flow engineering handbooks like Idelchik20 do not exist for investigators interested in acoustic (oscillating) fluid flows in complex resonators. Measurements of acoustic minor loss coefficients are presented in this dissertation for a limited number of resonator configurations having single-sided junctions. While these results may be useful, the greater purpose of this work is to provide a set of controlled measurements that can be used to benchmark computational models of acoustic flows used for more complicated resonator structures. The experiments are designed around a driver operating at 150 Hz enabling acoustic pressures in excess of 10k Pa in liquid cooled, temperature controlled resonators with 90°, 45° and 25° junctions. These junctions join a common 109 cm long 4.7 cm diameter section to a section of 8.4 mm diameter tube making two sets of resonators: one set with a small diameter length approximately a quarter-wavelength (45 cm), the other approximately a half-wavelength (112 cm). The long resonators have a velocity node at the junction; the short resonators have a velocity anti-node generating the greatest minor losses. Input power is measured by an accelerometer and a pressure transducer at the driver. A pressure sensor at the rigid termination measures radiation pressure from the driver and static junction pressure, as well as the acoustic pressure used to calculate linear thermal and viscous resonator wall losses. At the largest amplitudes, the 90° junction was found to dissipate as much as 0.3 Watt, 1/3 the power of linear losses alone. For each junction, the power dissipation depends on acoustic pressure differently: pressure cubed for the 90°, pressure to the 3.76 for the 45° and pressure to the 4.48 for the 25°. Common among all resonators, blowing acoustic half-cycle minor losses (KB) are excited at lower amplitudes than the suction half-cycle (KS) minor losses. Data collected for the 90° junction shows KB reaches an asymptotic value 40% greater than suggested by Idelchik20 for steady flow. Although, values for KB for the conical junctions and KS for 90° junction agree with Idelchik20, the slopes of the data do not suggest an asymptotic value is reached.

  15. Evaluation of a Hopkinson bar fly-away technique for high amplitude shock accelerometer calibration

    Energy Technology Data Exchange (ETDEWEB)

    Togami, T.C.; Bateman, V.I.; Brown, F.A.

    1997-11-01

    A split Hopkinson bar technique has been developed to evaluate the performance of accelerometers that measure large amplitude pulses. An evaluation of this technique has been conducted in the Mechanical Shock Laboratory at Sandia National Laboratories (SNL) to determine its use in the practical calibration of accelerometers. This evaluation consisted of three tasks. First, the quartz crystal was evaluated in a split Hopkinson bar configuration to evaluate the quartz gage`s sensitivity and frequency response at force levels of 18,000, 35,000 and 53,000 N at ambient temperature, {minus}48 C and +74 C. Secondly, the fly away technique was evaluated at shock amplitudes of 50,000, 100,000, 150,000 and 200,000 G (1 G = 9.81 m/s{sup 2}) at ambient temperature, {minus}48 C and +74 C. Lastly, the technique was performed using a NIST calibrated reference accelerometer. Comparisons of accelerations calculated from the quartz gage data and the measured acceleration data have shown very good agreement. Based on this evaluation, the authors expect this split Hopkinson fly away technique to be certified by the SNL Primary Standards Laboratory.

  16. Discovery of a long-lived, high-amplitude dusty infrared transient

    Science.gov (United States)

    Britt, C. T.; Maccarone, T. J.; Green, J. D.; Jonker, P. G.; Hynes, R. I.; Torres, M. A. P.; Strader, J.; Chomiuk, L.; Salinas, R.; Lucas, P.; Contreras Peña, C.; Kurtev, R.; Heinke, C.; Smith, L.; Wright, N. J.; Johnson, C.; Steeghs, D.; Nelemans, G.

    2016-08-01

    We report the detection of an infrared-selected transient which has lasted at least five years, first identified by a large mid-infrared and optical outburst from a faint X-ray source detected with the Chandra X-ray Observatory. In this paper we rule out several scenarios for the cause of this outburst, including a classical nova, a luminous red nova, AGN flaring, a stellar merger, and intermediate luminosity optical transients, and interpret this transient as the result of a young stellar object (YSO) of at least solar mass accreting material from the remains of the dusty envelope from which it formed, in isolation from either a dense complex of cold gas or massive star formation. This object does not fit neatly into other existing categories of large outbursts of YSOs (FU Orionis types) which may be a result of the object's mass, age, and environment. It is also possible that this object is a new type of transient unrelated to YSOs.

  17. MASTER: high amplitude (>6.8m) optical transient and new OT

    Science.gov (United States)

    Gress, O.; Pogrosheva, T.; Lipunov, V.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kuznetsov, A.; Kornilov, V.; Chazov, V.; Vladimirov, V.; Shumkov, V.; Kuvshinov, D.; Ivanov, K.; Budnev, N.; Tlatov, A.; Senik, V.

    2017-02-01

    MASTER-Tunka auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 19h 12m 48.12s +37d 49m 34.6s on 2017-01-31.86338 UT. The OT unfiltered magnitude is (limit 18.4m).

  18. Short duration high amplitude flares detected on the M dwarf star KIC 5474065

    CERN Document Server

    Ramsay, Gavin; Hakala, Pasi; Garcia-Alvarez, David; Brooks, Adam; Barclay, Thomas; Still, Martin

    2013-01-01

    Using data obtained during the RATS-Kepler project we identified one short duration flare in a 1 hour sequence of ground based photometry of the dwarf star KIC 5474065. Observations made using GTC show it is a star with a M4 V spectral type. Kepler observations made using 1 min sampling show that KIC 5474065 exhibits large amplitude (deltaF/F>0.4) optical flares which have a duration as short as 10 mins. We compare the energy distribution of flares from KIC 5474065 with that of KIC 9726699, which has also been observed using 1 min sampling, and ground based observations of other M dwarf stars in the literature. We discuss the possible implications of these short duration, relatively low energy flares would have on the atmosphere of exo-planets orbiting in the habitable zone of these flare stars.

  19. Implications of high amplitude atmospheric CO2 fluctuations on past millennium climate change

    Science.gov (United States)

    van Hoof, Thomas; Kouwenberg, Lenny; Wagner-Cremer, Friederike; Visscher, Henk

    2010-05-01

    Stomatal frequency analysis of leaves of land plants preserved in peat and lake deposits can provide a proxy record of pre-industrial atmospheric CO2 concentration complementary to measurements in Antarctic ice cores. Stomatal frequency based CO2 trends from the USA and NW European support the presence of significant CO2 variability during the first half of the last millennium (Kouwenberg et al., 2005; Wagner et al., 2004; van Hoof et al., 2008). The timing of the most significant perturbation in the stomata records (1200 AD) is in agreement with an observed CO2 fluctuation in the D47 Antarctic ice-core record (Barnola et al., 1995; van Hoof et al., 2005). The amplitude of the stomatal frequency based CO2 changes (> 34ppmv) exceeds the maximum amplitude of CO2 variability in the D47 ice core (Proceedings of the National Academy of Sciences of the USA, v. 105, no. 41, pp. 15815-15818 Wagner F., L.L.R. Kouwenberg, T.B. van Hoof and H. Visscher 2004. Reproducibility of Holocene atmospheric CO2 records based on stomatal frequency. Quartenary Science Reviews. V. 23, pp. 1947-1954

  20. Skeletal bone morphology is resistant to the high amplitude seasonal leptin cycle in the Siberian hamster.

    Science.gov (United States)

    Rousseau, K; Atcha, Z; Denton, J; Cagampang, F R A; Ennos, A R; Freemont, A J; Loudon, A S I

    2005-09-01

    Recent studies have suggested that the adipocyte-derived hormone, leptin, plays a role in the regulation of metabolism. Here, we tested this hypothesis in the seasonally breeding Siberian hamster, as this species exhibits profound seasonal changes in adiposity and circulating leptin concentrations driven by the annual photoperiodic cycle. Male hamsters were kept in either long (LD) or short (SD) photoperiods. Following exposure to short photoperiods for 8 weeks animals exhibited a significant weight-loss and a 16-fold reduction of serum leptin concentrations. At Week 9, animals in both photoperiods were infused with leptin or PBS via osmotic mini-pump for 14 days. Chronic leptin infusion mimicked LD-like concentrations in SD-housed animals and caused a further decline in body weight and adipose tissue. In LD-housed animals, leptin infusion resulted in a significant elevation of serum concentrations above natural LD-like levels, but had no discernable effect on body weight or overall adiposity. Both bending and compression characteristics and histomorphometric measurements of trabecular bone mass were unaltered by leptin treatment or photoperiod. Our data therefore show that despite a high natural amplitude cycle of leptin, this hormone has no apparent role in the regulation of bone metabolism, and therefore do not support recent propositions that this hormone is an important component in the metabolism of bone tissue.

  1. An unusual very low-mass high-amplitude pre-main sequence periodic variable

    CERN Document Server

    Rodriguez-Ledesma, Maria V; Ibrahimov, Mansur; Messina, Sergio; Parihar, Padmakar; Hessman, Frederic; de Oliveira, Catarina Alves; Herbst, William

    2012-01-01

    We have investigated the nature of the variability of CHS7797, an unusual periodic variable in the Orion Nebula Cluster. An extensive I-band photometric data set of CHS7797 was compiled between 2004-2010 using various telescopes. Further optical data have been collected in R and z' bands. In addition, simultaneous observations of the ONC region including CHS7797 were performed in the I, J, Ks and IRAC [3.6] and [4.5] bands over a time interval of about 40d. CHS7797 shows an unusual large-amplitude variation of about 1.7 mag in the R, I, and z' bands with a period 17.786. The amplitude of the brightness modulation decreases only slightly at longer wavelengths. The star is faint during 2/3 of the period and the shape of the phased light-curves for seven different observing seasons shows minor changes and small-amplitude variations. Interestingly, there are no significant colour-flux correlations for wavelengths smaller than 2microns, while the object becomes redder when fainter at longer wavelengths. CHS7797 ha...

  2. Thermal effects on seeded finite ion temperature, high amplitude plasma blobs

    CERN Document Server

    Held, M; Madsen, J; Kendl, A

    2016-01-01

    Thermal effects on the perpendicular convection of seeded pressure blobs in the scrape-off layer of magnetised fusion plasmas are investigated. Our numerical study is based on a four field full-F gyrofluid model, which entails the consistent description of high fluctuation amplitudes and dynamic finite Larmor radius effects. We find that a temperature perturbation increases the maximal blob velocity and that a finite Larmor radius contributes to highly compact blob structures with finite poloidal motion. An extensive parameter study reveals that a smooth transition to this compact blob regime occurs when the finite Larmor radius effect strength, defined by the ratio of the ion diamagnetic to the perpendicular vorticity, exceeds unity. The maximal blob velocities excellently agree with the inertial velocity scaling law over more than an order of magnitude. We show that the finite Larmor radius effect strength affects the radial transport and verify the here presented empirical scaling law for the maximal radia...

  3. 陕西延川黄河蛇曲国家地质公园地质遗迹特征与旅游开发价值%Geosite Features and Tourism Values of the Yellow River Meanders National Geopark in Yanchuan County, Shaanxi Province

    Institute of Scientific and Technical Information of China (English)

    薛滨瑞; 彭永祥; 张立文

    2011-01-01

    陕西延川黄河蛇曲国家地质公园是我国目前最密集,规模最大、发育最完好的干流峡谷型蛇曲.她以黄河秦晋大峡谷壮丽的自然景观为依托,以河流地质遗迹景观和黄土地貌景观为主体,以人文景观为陪衬,给游客提供优美舒适的户外游憩环境,集开发科学考察、科普教育、游览观光、生态旅游、休闲度假为一体的多功能地质公园.但地质遗迹资源自身价值的优势并不能完全代表旅游开发的价值.衡量其旅游开发价值,必须从旅游者消费需求角度出发,合理规划和开发建设.%The meanders of the Yellow River in Yanchuan County is the most intensive, largest scale and best-developed canyon-type meanders along the main stream in China. Both the magnificent natural landscape in Qin-Jin Grand Gorge and the abundant cultural landscape provide a perfect site for observing fiver geological remains and loess landscape. Tourists will enjoy a beautiful and comfortable recreation environment in the park,which offers multiple functions such as scientific investigation, scientific education, eco-tourism, and leisure.However, the value of geological remains is not wholly equal to the tourism value. In order to make a rational decision for implementing planning, exploitation and construction, it is necessary to assess the whole value from the angle of tourists' demand.

  4. Teachers in Children's Mind: Interview with Professor Kinoshita Yuriko%儿童心目中的教师——日本教育学者木下百合子教授访谈

    Institute of Scientific and Technical Information of China (English)

    钟启泉

    2009-01-01

    本文围绕儿童心目中的教师形象的论题,分析了如何联系儿童的"认知型教师形象",去准确地把握他们所抱有的"假定型教师形象"与"理想型教师形象"的必要性.真真切切地把握不同年龄阶段儿童的教师认知的发展脉络,是每一个教师(特别是班主任教师)得以成功的秘诀.

  5. Pulsation and Long-Term Variability of the High-Amplitude δ Scuti Star AD Canis Minoris

    Institute of Scientific and Technical Information of China (English)

    Pongsak Khokhuntod; Jian-Ning Fu; Chayan Boonyarak; Kanokwan Marak; Li Chen; Shi-Yang Jiang

    2007-01-01

    Time-series photometry was made for the large-amplitude δ Scuti star AD CMi in 2005 and 2006.High-quality photometric data provided in the literature were used to analyze the pulsation of the star,with the derived multiple frequencies fitted to our new data.Besides the dominant frequency and its harmonics,one low frequency(2.27402 cd-1)is discovered,which provides a reasonable interpretation for the long-noticed luminosity variation at the maximum and minimum light.Combining the nine new times of light maxima determined from the new data with the 64 times collected from the literature.we analyzed the long-term variability of AD CMi with the O-C technique.The results provide the updated value of period of 0.122974478 days.and seem to be in favor of the model of combination of the evolutionary effect and light-time effect of a binary system.of which some parameters are hereby deduced.

  6. Mechanism associated with the Space Shuttle main engine oxidizer valve/duct system anomalous high amplitude discrete acoustical excitation

    Science.gov (United States)

    Schutzenhofer, L. A.; Jones, J. H.; Jewell, R. E.; Ryan, R. S.

    1980-01-01

    Anomalous high frequency pressure fluctuations in the Space Shuttle main engine have been experienced during hot firings. Through diagnostic analysis of hot firing engine data, it was determined that this excitation originated at the main oxidizer valve. The intensity of these fluctuations was such that the main oxidizer valve was partially consumed in fire, experienced fretting, and had seal damage. Delineated in this paper are the associated dynamical phenomena and the methodologies leading toward understanding the excitation mechanism. The results presented demonstrate that the source of the anomalous frequencies was suppressed by a simple fix and all main oxidizer valve damage was terminated.

  7. Pulsation and Long-Term Variability of the High-Amplitude δ Scuti Star AD Canis Minoris

    Science.gov (United States)

    Khokhuntod, Pongsak; Fu, Jian-Ning; Boonyarak, Chayan; Marak, Kanokwan; Chen, Li; Jiang, Shi-Yang

    2007-06-01

    Time-series photometry was made for the large-amplitude δ Scuti star AD CMi in 2005 and 2006. High-quality photometric data provided in the literature were used to analyze the pulsation of the star, with the derived multiple frequencies fitted to our new data. Besides the dominant frequency and its harmonics, one low frequency (2.27402 c d-1) is discovered, which provides a reasonable interpretation for the long-noticed luminosity variation at the maximum and minimum light. Combining the nine new times of light maxima determined from the new data with the 64 times collected from the literature, we analyzed the long-term variability of AD CMi with the O-C technique. The results provide the updated value of period of 0.122974478 days, and seem to be in favor of the model of combination of the evolutionary effect and light-time effect of a binary system, of which some parameters are hereby deduced.

  8. Characterization of a Setup to test the Impact of High-Amplitude Pressure Waves on Living Cells

    Science.gov (United States)

    Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O.

    2014-01-01

    The impact of pressure waves on cells may provide several possible applications in biology and medicine including the direct killing of tumors, drug delivery or gene transfection. In this study we characterize the physical properties of mechanical pressure waves generated by a nanosecond laser pulse in a setup with well-defined cell culture conditions. To systematically characterize the system on the relevant length and time scales (micrometers and nanoseconds) we use photon Doppler velocimetry (PDV) and obtain velocity profiles of the cell culture vessel at the passage of the pressure wave. These profiles serve as input for numerical pressure wave simulations that help to further quantify the pressure conditions on the cellular length scale. On the biological level we demonstrate killing of glioblastoma cells and quantify experimentally the pressure threshold for cell destruction. PMID:24458018

  9. The Kep-Cont Mission: Continuing the observation of high-amplitude variable stars in the Kepler field of view

    CERN Document Server

    Molnár, L; Kolenberg, K; Borkovits, T; Antoci, V; Vida, K; Ngeow, C C; Guzik, J A; Plachy, E; Castanheira, B

    2013-01-01

    As a response to the Kepler white paper call, we propose to keep Kepler pointing to its current field of view and continue observing thousands of large amplitude variables (Cepheid, RR Lyrae and delta Scuti stars among others) with high cadence in the Kep-Cont Mission. The degraded pointing stability will still allow observation of these stars with reasonable (better than millimag) precision. The Kep-Cont mission will allow studying the nonradial modes in Blazhko-modulated and first overtone RR Lyrae stars and will give a better view on the period jitter of the only Kepler Cepheid in the field. With continued continuous observation of the Kepler RR Lyrae sample we may get closer to the origin of the century-old Blazhko problem. Longer time-span may also uncover new dynamical effects like apsidal motion in eclipsing binaries. A continued mission will have the advantage of providing unprecedented, many-years-long homogeneous and continuous photometric data of the same targets. We investigate the pragmatic detai...

  10. Hidden focal EEG seizures during prolonged suppressions and high-amplitude bursts in early infantile epileptic encephalopathy.

    Science.gov (United States)

    Al-Futaisi, Amna; Banwell, Brenda; Ochi, Ayako; Hew, Justine; Chu, Bill; Oishi, Makoto; Otsubo, Hiroshi

    2005-05-01

    We report on a 27-month-old female with atypical early infantile epileptic encephalopathy (EIEE), who developed tonic spasms, partial seizures and myoclonic jerks along with episodic bradycardia at 5 days. We recorded digital electroencephalography (EEG) using either an 11-channel neonatal montage or 19 channel scalp electrodes, at 200 Hz sampling rate, and a single reference for a minimum of 30 min. At 18 days EEG showed suppression-burst (SB) patterns during wakefulness and sleep. Tonic spasms concomitant with bursts recorded as brief, low-amplitude fast waves. EEG at 8 months showed increased amplitude of bursts to 1 mV and extension of suppression periods to 65 s. By increasing recording sensitivity, we detected focal epileptiform discharges of slow rhythmic sharp and slow waves building to 30 microV during suppression periods. Status epilepticus occurred at 16 months. EEG at 27 months returned to the previous SB pattern with rare partial seizures. This report is the first to demonstrate clinically silent focal EEG seizures during prolonged suppression periods in atypical EIEE by off-line digital EEG. Digital EEG sensitivity can reveal covert electrical activity during suppression periods in epileptic neonates and infants.

  11. High-amplitude supergiant V5112 Sgr: enrichment of the envelope with heavy s-process metals

    CERN Document Server

    Klochkova., V G

    2013-01-01

    High-resolution (R=60000) echelle spectroscopy of the post-AGB supergiant V5112 Sgr performed in 1996-2012 with the 6-m telescope BTA has revealed peculiarities of the star optical spectrum and has allowed the variability of the velocity field in the stellar atmosphere and envelope to be studied in detail. An asymmetry and splitting of strong absorption lines with a low lower-level excitation potential have been detected for the first time. The effect is maximal in BaII lines whose profile is split into three components. The profile shape and positions of the split lines change with time. The blue components of the split absorption lines are shown to be formed in a structured circumstellar envelope, suggesting an efficient dredge-up of the heavy metals produced during the preceding evolution of this star into the envelope. The envelope expansion velocities have been estimated to be 20 and 30 km/s. The mean radial velocity from diffuse bands in the spectrum of V5112 Sgr coincides with that from the short-wavel...

  12. Asteroseismology of KIC\\,11754974: a high-amplitude SX\\,Phe pulsator in a 343-day binary system

    CERN Document Server

    Murphy, S J; Kurtz, D W; Suarez, J C; Handler, G; Balona, L A; Smalley, B; Uytterhoeven, K; Szabo, R; Thygesen, A O; Elkin, V; Breger, M; Grigahcene, A; Guzik, J A; Nemec, J M; Southworth, J

    2013-01-01

    The candidate SX Phe star KIC 11754974 shows a remarkably high number of combination frequencies in the Fourier amplitude spectrum: 123 of the 166 frequencies in our multi-frequency fit are linear combinations of independent modes. Predictable patterns in frequency spacings are seen in the Fourier transform of the light curve. We present an analysis of 180 d of short-cadence Kepler photometry and of new spectroscopic data for this evolved, late A-type star. We infer from the 1150-d, long-cadence light curve, and in two different ways, that our target is the primary of a 343-d, non-eclipsing binary system. According to both methods, the mass function is similar, f(M)=0.0207 +/- 0.0003 Msun. The observed pulsations are modelled extensively, using separate, state-of-the-art, time-dependent convection (TDC) and rotating models. The models match the observed temperature and low metallicity, finding a mass of 1.50-1.56 Msun. The models suggest the whole star is metal-poor, and that the low metallicity is not just a...

  13. Technical Note: Is radiation important for the high amplitude variability of the MOC in the North Atlantic?

    Directory of Open Access Journals (Sweden)

    D. Nof

    2007-09-01

    Full Text Available Radiation is of fundamental importance to climate modeling and it is customary to assume that it is also important for the variability of North Atlantic Deep Water (NADW formation and the meridional overturning cell (MOC. Numerous articles follow this scenario and incorporate radiation into the calculation. Using relatively old heat-flux maps based on measurements taken in the nineteen sixties, Sandal and Nof (2007 recently suggested that, even though the radiation terms are of the same order as the other heat-flux terms, they are not important for the variability of the NADW and the MOC. They proposed that only sensible and latent heat fluxes are important for the long-term variability of the convection, i.e., for processes such as Heinrich events, which supposedly correspond to turning convection on-and-off in the Atlantic.

    Here, we place this suggestion on a firmer ground by presenting new and accurate up-to-date heat flux maps that also suggest that the radiation is of no major consequence to the NADW variability. Also, we attribute the relative importance of sensible and latent heat fluxes and the contrasting negligible role of radiation to the fact that the latent and sensible heat fluxes are primarily proportional to the difference between the sea surface and the air temperature whereas the radiation is primarily proportional to the sea surface temperature, i.e., radiation is approximately independent of the atmospheric temperature. Due the small heat capacity ratio of air/water (1/4, the difference between the ocean temperature and the air temperature varies dramatically between the state of active and inactive MOC, whereas the ocean temperature by itself varies very modestly between a state of active and inactive convection.

  14. The influence of temperature dynamics and dynamic finite ion Larmor radius effects on seeded high amplitude plasma blobs

    Science.gov (United States)

    Held, M.; Wiesenberger, M.; Madsen, J.; Kendl, A.

    2016-12-01

    Thermal effects on the perpendicular convection of seeded pressure blobs in the scrape-off layer of magnetised fusion plasmas are investigated. Our numerical study is based on a four field full-F gyrofluid model, which entails the consistent description of high fluctuation amplitudes and dynamic finite Larmor radius effects. We find that the maximal radial blob velocity increases with the square root of the initial pressure perturbation and that a finite Larmor radius contributes to highly compact blob structures that propagate in the poloidal direction. An extensive parameter study reveals that a smooth transition to this compact blob regime occurs when the finite Larmor radius effect strength, defined by the ratio of the magnetic field aligned component of the ion diamagnetic to the \\boldsymbol{E}× \\boldsymbol{B} vorticity, exceeds unity. The maximal radial blob velocities agree excellently with the inertial velocity scaling law over more than an order of magnitude. We show that the finite Larmor radius effect strength affects the poloidal and total particle transport and present an empirical scaling law for the poloidal and total blob velocities. Distinctions to the blob behaviour in the isothermal limit with constant finite Larmor radius effects are highlighted.

  15. A novel high amplitude piezoceramic actuator for applications in magnetic resonance elastography: a compliant mechanical amplifier approach

    Science.gov (United States)

    Arani, Arvin; Eskandari, Amiraslan; Ouyang, Puren; Chopra, Rajiv

    2017-08-01

    Piezoceramic actuators are capable of precise positioning with high force, but suffer from limited displacement range, which has hindered their application in the field of magnetic resonance elastography (MRE). The objective of this study was to investigate the feasibility of using a mechanical amplifier in combination with a piezoceramic actuator for the application of endorectal prostate MRE. A five-bar symmetric structure was designed in ANSYS® and manufactured out of brass. Laser vibrometer measurements were used to characterize the amplitude of the CMA actuator while attached to masses in the 0-325 g range and over operating frequencies of 90-500 Hz. The response of the CMA was investigated while mechanically coupled to a balloon type endorectal coil. The resonant frequency of the prototype CMA actuator was predicted within 10% error using ANSYS simulations. The amplification ratio of the CMA actuator was measured to be 10 with the laser vibrometer and 7.6 ± 1.7 (max: 9.2, min: 6.5) using MRE, at a vibration frequency of 200 Hz. Laser vibrometer data also showed that the CMA actuator’s performance did not change whether it was connected to an empty or inflated endorectal. The feasibility of performing endorectal prostate MRE with a CMA actuator was successfully demonstrated in a human volunteer.

  16. The influence of temperature dynamics and dynamic finite ion Larmor radius effects on seeded high amplitude plasma blobs

    DEFF Research Database (Denmark)

    Held, Magnus; Wiesenberger, M.; Madsen, Jens

    2016-01-01

    Thermal effects on the perpendicular convection of seeded pressure blobs in the scrape-off layer of magnetised fusion plasmas are investigated. Our numerical study is based on a four field full-F gyrofluid model, which entails the consistent description of high fluctuation amplitudes and dynamic...

  17. 曲折型三明治结构FeNi/Cu/FeNi多层膜巨磁阻抗效应研究%Study on giant magneto-impedance effect in FeNi/Cu/FeNi multilayer films with meandering sandwich structure

    Institute of Scientific and Technical Information of China (English)

    夏鹏; 陈磊; 雷剑; 王韬; 周勇

    2011-01-01

    The FeNi/Cu/FeNi multilayer films with meandering sandwich structure were prepared on the glass substrate by using micro electromechanical systems (MEMS) technique. The giant magneto-impedance (GMI) effect was investigated in the current frequency range of 1-40 MHz with external magnetic field Ha applied along the longitudinal axis of the sample. And the effects of sizes of the FeNi film and Cu film on GMI effect were researched through changing their width and thickness. The results show that GMI ratio increases with the increasing of Ha and achieves the positive maximum value at a certain magnetic field strength, then decreases to the negative value with further increase of Ha, When the current frequency is 2 MHz and Ha is 2 kA ·m-1, the positive maximum GMI ratio reaches 169.85%.%采用微机电系统(MEMS)技术在玻璃基片上制备了曲折型三明治结构FeNi/Cu/FeNi多层膜,在电流频率1~40 MHz范围内研究了FeNi/Cu/FeNi多层膜的巨磁阻抗(GMI)效应,并分别通过改变FeNi薄膜的宽度、厚度和Cu薄膜的宽度,研究了尺寸对巨磁阻抗效应的影响,当磁场Ha施加在薄膜的纵轴时,巨磁阻抗变化率随磁场强度的增加而增大,在某一磁场强度下达到最大值,然后随磁场强度的增加而下降到负值.在电流频率为2 MHz,磁场强度为2kA · m-1时,巨磁阻抗变化率达到最大值169.85%.

  18. Mid-infrared plasmonic inductors: enhancing inductance with meandering lines.

    Science.gov (United States)

    Torres, Víctor; Ortuño, Rubén; Rodríguez-Ulibarri, Pablo; Griol, Amadeu; Martínez, Alejandro; Navarro-Cía, Miguel; Beruete, Miguel; Sorolla, Mario

    2014-01-07

    We present a mid-infrared inductor that when applied to an extraordinary transmission hole array produces a strong redshift of the resonant peak accompanied by an unprecedented enlargement of the operation bandwidth. The importance of the result is twofold: from a fundamental viewpoint, the direct applicability of equivalent circuit concepts borrowed from microwaves is demonstrated, in frequencies as high as 17 THz upholding unification of plasmonics and microwave concepts and allowing for a simplification of structure design and analysis; in practical terms, a broadband funnelling of infrared radiation with fractional bandwidth and efficiency as high as 97% and 48%, respectively, is achieved through an area less than one hundredth the squared wavelength, which leads to an impressive accessible strong field localization that may be of great interest in sensing applications.

  19. The meandering mind: vection and mental time travel.

    Directory of Open Access Journals (Sweden)

    Lynden K Miles

    Full Text Available BACKGROUND: The ability to travel mentally through time sets humans apart from many other species, yet little is known about this core cognitive capacity. In particular, what shapes the passage of the mind's journey through time? Guided by the viewpoint that higher cognitive activity can have a sensory-motor grounding, we explored the possibility that mental time travel is influenced by apparent movement through space. METHODOLOGY/PRINCIPAL FINDINGS: Participants performed a mundane vigilance task, during which they were expected to daydream, while viewing a display that elicited an illusion of self-motion (i.e., vection. Afterwards, the contents of their mind wandering experiences were probed. The results revealed that the direction of apparent motion influenced the temporal focus of mental time travel. While backward vection prompted thinking about the past, forward vection triggered a preponderance of future-oriented thoughts. CONCLUSIONS/SIGNIFICANCE: Consistent with recent evidence that traveling mentally through time entails associated movements in space, the current results demonstrate the converse relationship-apparent movement through space influenced the temporal locus of mental activity. Together, these findings corroborate the viewpoint that mental time travel may be grounded in the embodiment of spatiotemporal information in a bidirectional manner.

  20. The design secret of kyokusui-no-en's meandering channel

    OpenAIRE

    Tsubaki, Ryota; Nakayama, Yasuki; Fujita, Ichiro

    2008-01-01

    The purpose of this study is to investigate the characteristics of the flow through the Jonangu channel which is used for ceremonial game called as ‘Kyokusui-no-En' in Japanese. The geometry of the channel is measured, a visualization technique is used to measure the actual flow characteristics, and then a numerical flow model is used to represent the flow including unsteady flow characteristics. Numerical model of drifting cup is introduced to investigate an interaction between flow and moti...

  1. Meandering worms: mechanics of undulatory burrowing in muds

    OpenAIRE

    Dorgan, Kelly M.; Law, Chris J.; Rouse, Greg W.

    2013-01-01

    Recent work has shown that muddy sediments are elastic solids through which animals extend burrows by fracture, whereas non-cohesive granular sands fluidize around some burrowers. These different mechanical responses are reflected in the morphologies and behaviours of their respective inhabitants. However, Armandia brevis, a mud-burrowing opheliid polychaete, lacks an expansible anterior consistent with fracturing mud, and instead uses undulatory movements similar to those of sandfish lizards...

  2. Meandering worms: mechanics of undulatory burrowing in muds

    National Research Council Canada - National Science Library

    Dorgan, Kelly M; Law, Chris J; Rouse, Greg W

    2013-01-01

    .... However, Armandia brevis, a mud-burrowing opheliid polychaete, lacks an expansible anterior consistent with fracturing mud, and instead uses undulatory movements similar to those of sandfish lizards...

  3. Diagnosing Meridional Meandering of the Antarctic Circumpolar Current

    Science.gov (United States)

    Gille, S. T.; Shao, A.

    2008-12-01

    Long-term warming trends in the Southern Ocean appear consistent with a multi-decadal scale poleward migration of the Antarctic Circumpolar Current (ACC), possibly linked to a long-term shift in the Southern Annular Mode. Since historic in situ hydrographic data are sparse, definitive assessments of the actual trends and mechanisms governing them have proved difficult. Satellite data offer some promise for evaluating the meridional migrations of the ACC. However, studies carried out using microwave sea surface temperature (SST) data as well as satellite altimetry have sometimes reached differing conclusions. In part these differences may stem from the variety of definitions used to locate the frontal jets that define the ACC, which have been based on absolute sea surface height, gradients in sea surface height, or gradients in SST. In addition alternate statistical measures, such as the variance and skewness of sea surface height, have been proposed as means to identify the position of the ACC. This study represents an effort to identify consistent and robust definitions of the ACC jets from satellite altimeter data and to make use of these to investigate the physical processes governing ACC variability.

  4. Very Rapid High-amplitude Gamma-Ray Variability in Luminous Blazar PKS 1510-089 Studied with Fermi-LAT

    Energy Technology Data Exchange (ETDEWEB)

    Saito, S.; Stawarz, L.; Tanaka, Y.T.; Takahashi, T.; Madejski, G.; D' Ammando, F.

    2013-03-20

    Here we report on the detailed analysis of the γ-ray light curve of a luminous blazar PKS 1510-089 observed in the GeV range with the Large Area Telescope (LAT) onboard the Fermi satellite during the period 2011 September - December. By investigating the properties of the detected three major flares with the shortest possible time binning allowed by the photon statistics, we find a variety of temporal characteristics and variability patterns. This includes a clearly asymmetric profile (with a faster flux rise and a slower decay) of the flare resolved on sub-daily timescales, a superposition of many short uncorrelated flaring events forming the apparently coherent longer-duration outburst, and a huge single isolated outburst unresolved down to the timescale of three-hours. In the latter case we estimate the corresponding γ-ray flux doubling timescale to be below one hour, which is extreme and never previously reported for any active galaxy

  5. Detection of a 1258 Hz high-amplitude kilohertz quasi-periodic oscillation in the ultra-compact X-ray binary 1A 1246-588

    CERN Document Server

    Jonker, P G; Méndez, M; Van der Klis, M

    2007-01-01

    We have observed the ultra-compact low-mass X-ray binary (LMXB) 1A 1246-588 with the Rossi X-ray Timing Explorer (RXTE). In this manuscript we report the discovery of a kilohertz quasi-periodic oscillation (QPO) in 1A 1246-588. The kilohertz QPO was only detected when the source was in a soft high-flux state reminiscent of the lower banana branch in atoll sources. Only one kilohertz QPO peak is detected at a relatively high frequency of 1258+-2 Hz and at a single trial significance of more than 7 sigma. Kilohertz QPOs with a higher frequency have only been found on two occasions in 4U 0614+09. Furthermore, the frequency is higher than that found for the lower kilohertz QPO in any source, strongly suggesting that the QPO is the upper of the kilohertz QPO pair often found in LMXBs. The full-width at half maximum is 25+-4 Hz, making the coherence the highest found for an upper kilohertz QPO. From a distance estimate of ~6 kpc from a radius expansion burst we derive that 1A 1246-588 is at a persistent flux of ~0....

  6. Cloud Atlas: Discovery of Patchy Clouds and High-amplitude Rotational Modulations in a Young, Extremely Red L-type Brown Dwarf

    Science.gov (United States)

    Lew, Ben W. P.; Apai, Daniel; Zhou, Yifan; Schneider, Glenn; Burgasser, Adam J.; Karalidi, Theodora; Yang, Hao; Marley, Mark S.; Cowan, Nicolas B.; Bedin, Luigi R.; Metchev, Stanimir A.; Radigan, Jacqueline; Lowrance, Patrick J.

    2016-10-01

    Condensate clouds fundamentally impact the atmospheric structure and spectra of exoplanets and brown dwarfs, but the connections between surface gravity, cloud structure, dust in the upper atmosphere, and the red colors of some brown dwarfs remain poorly understood. Rotational modulations enable the study of different clouds in the same atmosphere, thereby providing a method to isolate the effects of clouds. Here, we present the discovery of high peak-to-peak amplitude (8%) rotational modulations in a low-gravity, extremely red (J-K s = 2.55) L6 dwarf WISEP J004701.06+680352.1 (W0047). Using the Hubble Space Telescope (HST) time-resolved grism spectroscopy, we find a best-fit rotational period (13.20 ± 0.14 hr) with a larger amplitude at 1.1 μm than at 1.7 μm. This is the third-largest near-infrared variability amplitude measured in a brown dwarf, demonstrating that large-amplitude variations are not limited to the L/T transition but are present in some extremely red L-type dwarfs. We report a tentative trend between the wavelength dependence of relative amplitude, possibly proxy for small dust grains lofted in the upper atmosphere, and the likelihood of large-amplitude variability. By assuming forsterite as a haze particle, we successfully explain the wavelength-dependent amplitude with submicron-sized haze particle sizes of around 0.4 μm. W0047 links the earlier spectral and later spectral type brown dwarfs in which rotational modulations have been observed; the large amplitude variations in this object make this a benchmark brown dwarf for the study of cloud properties close to the L/T transition.

  7. Cloud Atlas: Discovery of Patchy Clouds and High-amplitude Rotational Modulations In a Young, Extremely Red L-type Brown Dwarf

    CERN Document Server

    Lew, Ben W P; Zhou, Yifan; Schneider, Glenn; Burgasser, Adam J; Karalidi, Theodora; Yang, Hao; Marley, Mark S; Cowan, N B; Bedin,; R., L; Metchev, Stanimir A; Radigan, Jacqueline; Lowrance, Patrick J

    2016-01-01

    Condensate clouds fundamentally impact the atmospheric structure and spectra of exoplanets and brown dwarfs but the connections between surface gravity, cloud structure, dust in the upper atmosphere, and the red colors of some brown dwarfs remain poorly understood. Rotational modulations enable the study of different clouds in the same atmosphere, thereby providing a method to isolate the effects of clouds. Here we present the discovery of high peak-to-peak amplitude (8%) rotational modulations in a low-gravity, extremely red (J-Ks=2.55) L6 dwarf WISEP J004701.06+680352.1 (W0047). Using the Hubble Space Telescope (HST) time-resolved grism spectroscopy we find a best-fit rotational period (13.20$\\pm$0.14 hours) with a larger amplitude at 1.1 micron than at 1.7 micron. This is the third largest near-infrared variability amplitude measured in a brown dwarf, demonstrating that large-amplitude variations are not limited to the L/T transition but are present in some extremely red L-type dwarfs. We report a tentativ...

  8. The Evolution and Future Trends of Physical Education in Japan: Interview with Professor Kinoshita Yuriko%日本学校体育的演进及其未来走势——日本教育学者木下百合子教授访谈

    Institute of Scientific and Technical Information of China (English)

    钟启泉

    2009-01-01

    本文围绕保健与体育的论题,梳理了日本学校体育的理念及其历史发展.日本的学校体育经历了"身体教育"、"基于运动的教育"、"运动教育"三个里程碑.今后的学校体育需要超越以往时代侧重于某个方向的局面,保持上述三种方向的和谐共存.

  9. Multibeam Echosounding Survey in Meander Reach, Kootenai River near Bonners Ferry, Idaho - Water Year 2011

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — In 2009, the Kootenai Tribe of Idaho released and implemented the Kootenai River Habitat Restoration Master Plan. This plan aimed to restore, enhance, and maintain...

  10. 漫谈金属探测器%Meander about Metal Detector

    Institute of Scientific and Technical Information of China (English)

    司德平

    2006-01-01

    金属探测器(Metal Detector)是一种专门用来探测金属的仪器,除了用于探测有金属外壳或金属部件的地雷之外,还可用来探测隐蔽在墙壁内的电线、埋在地下的水管和电缆,甚至能够地下探宝,发现埋藏在地下的金属物体。目前还广泛应用于各种大型会议中心、会展场馆、体育场馆、公检法和监狱系统及娱乐场所的安全检查和工厂企业的防盗检查。另外,为了严肃考风考纪,有效防止高科技手段作弊,为众多考生营造一个公平、公正的考试环境,2005年全国硕士研究生入学统一考试和2005年普通高等学校招生全国统一考试中,部分省、市首次使用金属探测器。根据国务院发布的《单位内部治安保卫条例》,监考人员在考场里使用金属探测器符合相关规定,它将作为一项常规措施用于监考。本文就来简要介绍一下金属探测器的发展简史、发展现状、工作原理和技术性能。

  11. The meandering Indus, channels: Study in a small area by the multibeam swath bathymetry system - Hydrosweep

    Digital Repository Service at National Institute of Oceanography (India)

    Kodagali, V.N.; Jauhari, P.

    The discharge of sediments by the river Indus has accumulated into a 2500 m thick pile, forming one of the largest deep sea fans in the world. Though there are many reports on channels in different regions of tha fan, we report for the first time...

  12. Satellite Observations and Chemistry Climate Models - A Meandering Path Towards Better Predictions

    Science.gov (United States)

    Douglass, Anne R.

    2011-01-01

    Knowledge of the chemical and dynamical processes that control the stratospheric ozone layer has grown rapidly since the 1970s, when ideas that depletion of the ozone layer due to human activity were put forth. The concept of ozone depletion due to anthropogenic chlorine increase is simple; quantification of the effect is much more difficult. The future of stratospheric ozone is complicated because ozone is expected to increase for two reasons: the slow decrease in anthropogenic chlorine due to the Montreal Protocol and its amendments and stratospheric cooling caused by increases in carbon dioxide and other greenhouse gases. Prediction of future ozone levels requires three-dimensional models that represent physical, photochemical and radiative processes, i.e., chemistry climate models (CCMs). While laboratory kinetic and photochemical data are necessary inputs for a CCM, atmospheric measurements are needed both to reveal physical and chemical processes and for comparison with simulations to test the conceptual model that CCMs represent. Global measurements are available from various satellites including but not limited to the LIMS and TOMS instruments on Nimbus 7 (1979 - 1993), and various instruments on the Upper Atmosphere Research Satellite (1991 - 2005), Envisat (2002 - ongoing), Sci-Sat (2003 - ongoing) and Aura (2004 - ongoing). Every successful satellite instrument requires a physical concept for the measurement, knowledge of physical chemical properties of the molecules to be measured, and stellar engineering to design an instrument that will survive launch and operate for years with no opportunity for repair but providing enough information that trend information can be separated from any instrument change. The on-going challenge is to use observations to decrease uncertainty in prediction. This talk will focus on two applications. The first considers transport diagnostics and implications for prediction of the eventual demise of the Antarctic ozone hole. The second focuses on the upper stratosphere, where ozone is predicted to increase both due to chlorine decrease and due to temperature decrease expected as a result of increased concentrations Of CO2 and other greenhouse gases. Both applications show how diagnostics developed from global observations are being used to explain why the ozone response varies among CCM predictions for stratospheric ozone in the 21st century.

  13. Geomorphic adjustment to hydrologic modifications along a meandering river: Implications for surface flooding on a floodplain

    Science.gov (United States)

    Edwards, Brandon L.; Keim, Richard F.; Johnson, Erin L.; Hupp, Cliff R.; Marre, Saraline; King, Sammy L.

    2016-09-01

    Responses of large regulated rivers to contemporary changes in base level are not well understood. We used field measurements and historical analysis of air photos and topographic maps to identify geomorphic trends of the lower White River, Arkansas, USA, in the 70 years following base-level lowering at its confluence with the Mississippi River and concurrent with flood control by dams. Incision was identified below a knickpoint area upstream of St. Charles, AR, and increases over the lowermost ~90 km of the study site to ~2 m near the confluence with the Mississippi River. Mean bankfull width increased by 30 m (21%) from 1930 to 2010. Bank widening appears to be the result of flow regulation above the incision knickpoint and concomitant with incision below the knickpoint. Hydraulic modeling indicated that geomorphic adjustments likely reduced flooding by 58% during frequent floods in the incised, lowermost floodplain affected by backwater flooding from the Mississippi River and by 22% above the knickpoint area. Dominance of backwater flooding in the incised reach indicates that incision is more important than flood control on the lower White River in altering flooding and also suggests that the Mississippi River may be the dominant control in shaping the lower floodplain. Overall, results highlight the complex geomorphic adjustment in large river-floodplain systems in response to anthropogenic modifications and their implications, including reduced river-floodplain connectivity.

  14. Meandering Musings by Linus Pauling: "American Scientists and the Spirit of the Frontier".

    Science.gov (United States)

    Bause, George S

    2016-04-01

    Hoping to raise funds in 1975 for his namesake institute, Linus Pauling submitted to Esquire magazine a 32-page handwritten manuscript, "American Scientists and the Spirit of the Frontier." Angered when his submission for publication was declined, Pauling eventually gifted the original manuscript in 1986 to his friend, Linus Pauling Institute fundraiser Stephen Maddox, who would sell it in 2004 to the Wood Library-Museum of Anesthesiology. Published accurately here for the first time, the manuscript captures not only Pauling's sweeping metaphor of scientists as frontiersmen but also the creative process by which Pauling formulated his hydrate microcrystal theory of general anesthesia.

  15. Application of conditional nonlinear optimal perturbation method to the predictability study of the Kuroshio large meander

    NARCIS (Netherlands)

    Wang, Qiang; Mu, M.; Dijkstra, H.A.

    2012-01-01

    A reduced-gravity barotropic shallow-water model was used to simulate the Kuroshio path variations. The results show that the model was able to capture the essential features of these path variations. We used one simulation of the model as the reference state and investigated the effects of errors i

  16. Preservation of meander channel and scour features under aggradational and non-aggradational conditions

    NARCIS (Netherlands)

    Lageweg, W.I. van de; Schuurman, F.; Shimizu, Y.; Cohen, K.M.; Dijk, W.M. van; Kleinhans, M.G.

    2013-01-01

    The internal architecture of channel belts commonlyconsists of channel-form bounding surfaces due to channelmigration and scouring (e.g. Miall, 1985). These boundingsurfaces are essential to our reconstructions of palaeochannel dimensions. It is therefore crucial tounderstand the suite of processes

  17. Morphological adjustments in a meandering reach of the middle Yangtze River caused by severe human activities

    Science.gov (United States)

    Zhou, Meirong; Xia, Junqiang; Lu, Jinyou; Deng, Shanshan; Lin, Fenfen

    2017-05-01

    In the past 50 years, the Shishou reach in the middle Yangtze River underwent significant channel evolution owing to the implementation of an artificial cutoff, the construction of bank revetment works and the operation of the Three Gorges Project (TGP). Based on the measured hydrological data and topographic data, the processes of channel evolution in this reach were investigated mainly from the adjustments in planform and cross-sectional geometries. The variation in planform geometry obtained in this study indicates that (i) the artificial cutoff at Zhongzhouzi caused the river regime to adjust drastically, with the mean rate of thalweg migration at reach scale of 42.0 m/a over the period 1966-1975; (ii) then the effect of this artificial cutoff reduced gradually, with the mean migration rate decreasing to 40 m/a owing to the occurrence of high water levels in 1993-1998; and (iii) the average annual rate of thalweg migration decreased to 29.3 m/a because of the impacts of various bank protection engineering and the TGP operation during the period 2002-2015. However, remarkable thalweg migration processes still occurred in local regions after the TGP operation, which resulted in significant bankline migration in local reaches of Beimenkou, Shijiatai, and Tiaoxiankou. In addition, the adjustments of bankfull channel geometry were investigated at section and reach scales after the TGP operation. Calculated results show that lateral channel migration in this reach was restricted by various river regulation works and that channel evolution was mainly characterized by an increase in bankfull depth and cross-sectional area. Empirical relationships were developed between the reach-scale bankfull dimensions (depth and area), the bankfull widths at specified sections, and the previous 5-year average fluvial erosion intensity during flood seasons, with high correlation degrees between them being obtained.

  18. Cadastral PLSS Standardized Data - MeanderedWater, SE - Version 1.1

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This feature class is part of the Cadastral National Spatial Data Infrastructure (NSDI) CADNSDI publication data set for rectangular and non-rectangular Public Land...

  19. On the nature of meandering of the springtime western boundary current in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Gangopadhyay, A.; BharatRaj, G.N.; Chaudhuri, A.H.; Babu, M.T.; Sengupta, D.

    2192 Ocean Prediction System: Assimilation Strategies and Structured Data Models, inModern Approaches to Data Assimilation in Ocean Modeling, (Ed.P. Malanotte-Rizzoli), Elsevier Oceanography Series, Elsevier Science, Amsterdam, pp 413–452. Legeckis, R...

  20. HF Meander-Line Antenna Simulations and Investigations for NVIS on a HMMV

    Science.gov (United States)

    2016-09-28

    communication  systems  [1]-­‐  [3].   Typical  planar...beneficial   communication   coverage  within  300  km.       Researchers  from  the  late  1990s  tried  to  improve  NVIS...MLA  (dimensions  from  table  1)  integrated  into  the   roof  of  a  HMMV.  The   computer  model  for  the

  1. CLOUD STRUCTURE OF THE NEAREST BROWN DWARFS. II. HIGH-AMPLITUDE VARIABILITY FOR LUHMAN 16 A AND B IN AND OUT OF THE 0.99 μm FeH FEATURE

    Energy Technology Data Exchange (ETDEWEB)

    Buenzli, Esther [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Marley, Mark S. [NASA Ames Research Center, MS-245-3, Moffett Field, CA 94035 (United States); Apai, Dániel [Department of Astronomy, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Saumon, Didier [Los Alamos National Laboratory, Mail Stop F663, Los Alamos, NM 87545 (United States); Biller, Beth A. [Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Crossfield, Ian J. M. [Department of Planetary Sciences, University of Arizona, 1629 E. University Blvd, Tucson, AZ 85721 (United States); Radigan, Jacqueline, E-mail: buenzli@mpia.de [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2015-10-20

    The re-emergence of the 0.99 μm FeH feature in brown dwarfs of early- to mid-T spectral type has been suggested as evidence for cloud disruption where flux from deep, hot regions below the Fe cloud deck can emerge. The same mechanism could account for color changes at the L/T transition and photometric variability. We present the first observations of spectroscopic variability of brown dwarfs covering the 0.99 μm FeH feature. We observed the spatially resolved very nearby brown dwarf binary WISE J104915.57–531906.1 (Luhman 16AB), a late-L and early-T dwarf, with Hubble Space Telescope/WFC3 in the G102 grism at 0.8–1.15 μm. We find significant variability at all wavelengths for both brown dwarfs, with peak-to-valley amplitudes of 9.3% for Luhman 16B and 4.5% for Luhman 16A. This represents the first unambiguous detection of variability in Luhman 16A. We estimate a rotational period between 4.5 and 5.5 hr, very similar to Luhman 16B. Variability in both components complicates the interpretation of spatially unresolved observations. The probability for finding large amplitude variability in any two brown dwarfs is less than 10%. Our finding may suggest that a common but yet unknown feature of the binary is important for the occurrence of variability. For both objects, the amplitude is nearly constant at all wavelengths except in the deep K i feature below 0.84 μm. No variations are seen across the 0.99 μm FeH feature. The observations lend strong further support to cloud height variations rather than holes in the silicate clouds, but cannot fully rule out holes in the iron clouds. We re-evaluate the diagnostic potential of the FeH feature as a tracer of cloud patchiness.

  2. The improved 10th order QED expression for a_{\\mu} new results and related estimates

    CERN Document Server

    Kataev, A L

    2006-01-01

    New estimates of the 10th order QED corrections to the muon anomalous magnetic moment are presented. The estimates include the information on definite improved 10th order QED contributions to $a_{\\mu}$, calculated by Kinoshita and Nio. The final estimates are in good agreement with the ones, given recently by Kinoshita.

  3. Health Monitoring of Composite Overwrapped Pressure Vessels (COPVs) Using Meandering Winding Magnetometer ((MWM(Registered Trademark)) Eddy Current Sensors

    Science.gov (United States)

    Russell, Rick; Grundy, David; Jablonski, David; Martin, Christopher; Washabaugh, Andrew; Goldfine, Neil

    2011-01-01

    There are 3 mechanisms that affect the life of a COPV are: a) The age life of the overwrap; b) Cyclic fatigue of the metallic liner; c) Stress Rupture life. The first two mechanisms are understood through test and analysis. A COPV Stress Rupture is a sudden and catastrophic failure of the overwrap while holding at a stress level below the ultimate strength for an extended time. Currently there is no simple, deterministic method of determining the stress rupture life of a COPV, nor a screening technique to determine if a particular COPV is close to the time of a stress rupture failure. Conclusions: Demonstrated a correlation between MWM response and pressure or strain. Demonstrated the ability to monitor stress in COPV at different orientations and depths. FA41 provides best correlation with bottle pressure or stress.

  4. Hydrography, Great Salt Lake Meander, Published in 2008, 1:24000 (1in=2000ft) scale, Box Elder County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Hydrography dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from Other information as of 2008. It is described as 'Great Salt Lake...

  5. Into the meanders of fiction and reality: some common aspects between Castalian and Benedictines in The Glass Bead Game

    OpenAIRE

    Leopoldo, Raphael Novaresi

    2015-01-01

    This paper aims at making clear the striking similarity managed by Herman Hesse in The glass bead game in the making of a fictional secular institution, which can be called the Castalian Order, and in the literary portrayal of another one, existing at the faithful non-literary reality, the Benedictine Order. In order to achieve such goal, we will expose both congregations as they are presented by the novel’s narrator, while we focus on sparse characteristics along the story. Besides, we will ...

  6. Simple physics-based predictor for the number of river bars and the transition between meandering and braiding

    NARCIS (Netherlands)

    Crosato, A.; Mosselman, E.

    2009-01-01

    The number of bars that form in an alluvial channel cross section can be determined from a physics-based linear model for alluvial bed topography. The classical approach defines separators between ranges in which river planform styles with certain numbers of bars are linearly stable and linearly uns

  7. Abundance of zooplankton from different zones (pelagic and littoral) and time periods (morning and night) in two Amazonian meandering lakes

    OpenAIRE

    Erlei Cassiano Keppeler

    2003-01-01

    Durante 10 meses foi estudada a abundância do zooplâncton em dois lagos da Amazônia Sul-Ocidental, situados respectivamente nas coordenadas 10°02'36''S; 67°50'24''W (Lago Amapá) e 9°27'21"S; 67°31'39"W (Lago Pirapora). Ambos os lagos caracterizam-se como de meandro abandonado. O objetivo desse estudo foi comparar as regiões pelágica e litorânea, com base na abundäncia da comunidade zooplanctönica, bem como observar diferenças da distribuição dessa comunidade na coluna da água no período da ma...

  8. Into the meanders of fiction and reality: some common aspects between Castalian and Benedictines in The Glass Bead Game

    Directory of Open Access Journals (Sweden)

    Raphael Novaresi Leopoldo

    2015-04-01

    Full Text Available This paper aims at making clear the striking similarity managed by Herman Hesse in The glass bead game in the making of a fictional secular institution, which can be called the Castalian Order, and in the literary portrayal of another one, existing at the faithful non-literary reality, the Benedictine Order. In order to achieve such goal, we will expose both congregations as they are presented by the novel’s narrator, while we focus on sparse characteristics along the story. Besides, we will report to the Benedictines as an actual organism when they appear to possess traits unstated in the romance which may contribute to the present comparative study.

  9. AI's Philosophical Underpinnings: A Thinking Person's Walk through the Twists and Turns of Artificial Intelligence's Meandering Path

    Science.gov (United States)

    Colombano, Silvano; Norvig, Peter (Technical Monitor)

    2000-01-01

    Few human endeavors can be viewed both as extremely successful and unsuccessful at the same time. This is typically the case when goals have not been well defined or have been shifting in time. This has certainly been true of Artificial Intelligence (AI). The nature of intelligence has been the object of much thought and speculation throughout the history of philosophy. It is in the nature of philosophy that real headway is sometimes made only when appropriate tools become available. Similarly the computer, coupled with the ability to program (at least in principle) any function, appeared to be the tool that could tackle the notion of intelligence. To suit the tool, the problem of the nature of intelligence was soon sidestepped in favor of this notion: If a probing conversation with a computer could not be distinguished from a conversation with a human, then AI had been achieved. This notion became known as the Turing test, after the mathematician Alan Turing who proposed it in 1950. Conceptually rich and interesting, these early efforts gave rise to a large portion of the field's framework. Key to AI, rather than the 'number crunching' typical of computers until then, was viewed as the ability to manipulate symbols and make logical inferences. To facilitate these tasks, AI languages such as LISP and Prolog were invented and used widely in the field. One idea that emerged and enabled some success with real world problems was the notion that 'most intelligence' really resided in knowledge. A phrase attributed to Feigenbaum, one of the pioneers, was 'knowledge is the power.' With this premise, the problem is shifted from 'how do we solve problems' to 'how do we represent knowledge.' A good knowledge representation scheme could allow one to draw conclusions from given premises. Such schemes took forms such as rules,frames and scripts. It allowed the building of what became known as expert systems or knowledge based systems (KBS).

  10. Detection of Rare Antigen Presenting Cells through T cell-intrinsic meandering motility, mediated by Myo1g

    OpenAIRE

    Gérard, Audrey; Patino-Lopez, Genaro; Beemiller, Peter; Nambiar, Rajalakshmi; Ben-Aissa, Khadija; Liu, Yin; Totah, Fadi J.; Tyska, Matthew J.; Shaw, Stephen; Krummel, Matthew F.

    2014-01-01

    To mount an immune response, T lymphocytes must successfully search for foreign material bound to the surface of antigen-presenting cells. How T cells optimize their chances of encountering and responding to these antigens is unknown. T cell motility in tissues resembles a random or Levy walk and is regulated in part by external factors including chemokines and lymph node topology, but motility parameters such as speed and propensity to turn may also be cell-intrinsic. Here we found that the ...

  11. Hyperfinite Representation of Distributions

    Indian Academy of Sciences (India)

    J Sousa Pinto; R F Hoskins

    2000-11-01

    Hyperfinite representation of distributions is studied following the method introduced by Kinoshita [2, 3], although we use a different approach much in the vein of [4]. Products and Fourier transforms of representatives of distributions are also analysed.

  12. Burden of comorbidities among Japanese patients with atrial fibrillation: a case study of dyspepsia [Corrigendum

    Directory of Open Access Journals (Sweden)

    Kinoshita Y

    2013-09-01

    Full Text Available Kinoshita Y, DiBonaventura M, Rossi B, Iwamoto K, Wang ECY, Briere JB. Clin Exp Gastroenterol. 2013;6:51–59.On page 54, in the second paragraph, line 6, note that "26.65% versus 17.02%" should be "29.65% versus 17.02%".View original paper by Kinoshita Y, DiBonaventura M, Rossi B et al. 

  13. Micro Flow-Through Thermocycler with Simple Meandering Channel with Symmetric Temperature Zones for Disposable PCR-Devices in Microscope Slide Format

    Institute of Scientific and Technical Information of China (English)

    Anett Reichert; Jana Felbel; Mark Kielpinski; Matthias Urban; Benno Steinbrecht; Thomas Henkel

    2008-01-01

    Chip-based flow-through PCR implements the PCR as a continuous process for nucleic acid analytics. The sample is transported in a winding channel through temperature zones required for denaturation, annealing and extension. Main fields of application are the monitoring of continuous processes for rapid identification of contaminants and quality control as well as high throughput screening of cells or microorganisms. A modular arrangement with five heating zones for flow-through PCR is discussed and evaluated. The special heater arrangement allows the implementation of up to 40 cycles on the footprint of a microscope slide, which is placed on top ofa 5 zones heating plate. Liquid/liquid two phase flow of PCR reaction mixture and mineral oil have been applied to create a segmented flow process scheme. In that way, the developed system may provide flow-through PCR as a unit operation for the droplet based microfluidics platform. The single use of disposable devices is commonly preferred due to the sensitivity of the PCR process to contaminations. All-glass microfluidic chips and disposable chip devices, made from polycarbonate as a replication with identically geometry, have been fabricated and tested. For the fast time, microchannel geometries with nearly circular profile developed by all-glass technology have been transferred to mass fabrication by injection compression molding. Both devices have been successfully applied for the detection of the tumor suppressor gene p53. Although product yield and selectivity of the amplification process do not depend on the chip material, a well defmod, reliable segmented flow regime could only be realized in the all-glass chip.

  14. Disease: H00058 [KEGG MEDICUS

    Lifescience Database Archive (English)

    Full Text Available 4:581-91 (2001) PMID:20428114 (ALS12) Maruyama H, Morino H, Ito H, Izumi Y, Kato H, Watanabe Y, Kinoshita Y,...K, Suzuki N, Aoki M, Kawata A, Hirai T, Kato T, Ogasawara K, Hirano A, Takumi T, Kusaka H, Hagiwara K, Kaji

  15. Current Approaches to Assessment in Self-Access Language Learning

    Science.gov (United States)

    Reinders, Hayo; Lázaro, Noemí

    2007-01-01

    Assessment is generally seen as one of the key challenges in the field of self-access learning (Gardner & Miller, 1999; Champagne et al., 2001; Lai, 2001; Kinoshita Thomson, 1996). Many researchers and practitioners point to difficulties with assessing language gains in an environment in which variables cannot comprehensively be controlled…

  16. Reference: 19 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available 19 http://metadb.riken.jp/db/SciNetS_ria224i/cria224u4ria224u12569131i Lopez-Molina Luis... 410-8 12569131 2003 Feb Genes & development Chua Nam-Hai|Kinoshita Natsuko|Lopez-Molina Luis|Mongrand S辿bastien

  17. Database Description - SAHG | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available of Advanced Industrial Science and Technology (AIST) Journal Search: Creator Name...: Motonori Ota Creator Affiliation: Graduate School of Information Sciences, Nagoya University Journal Searc...rai, Kengo Kinoshita, Tamotsu Noguchi, Motonori Ota Journal: Nucleic Acids Research, 2011, Vol. 39, External

  18. Revision of the Antipatharia (Cnidaria: Anthozoa). Part III. Cladopathidae

    NARCIS (Netherlands)

    Opresko, D.M.

    2003-01-01

    The family of antipatharian corals Cladopathidae (Cnidaria: Anthozoa: Antipatharia) is revised. The family is characterized by polyps 2 mm or more in transverse diameter, six primary mesenteries, and no secondary mesenteries. The family is divided into three subfamilies: Cladopathinae Kinoshita, Hex

  19. QTL Information Table: 718 [Q-TARO

    Lifescience Database Archive (English)

    Full Text Available Dn-1 Morphological trait Panicle/flower Dense panicle RFLP d)Co-segregated F2 RG553... rgn Yu, Z.H., Kinoshita, T., Sato, S., and Tanksley, S.D. (1992). Morphological and RFLP markers are associated in rice. Rice Genetics Newsletter 9, 116-118. ...

  20. QTL Information Table: 719 [Q-TARO

    Lifescience Database Archive (English)

    Full Text Available d-27 Morphological trait Dwarf dwarf RFLP d)Co-segregated F2 RZ141 rgn Yu, Z.H., Ki...noshita, T., Sato, S., and Tanksley, S.D. (1992). Morphological and RFLP markers are associated in rice. Rice Genetics Newsletter 9, 116-118. ...

  1. QTL Information Table: 716 [Q-TARO

    Lifescience Database Archive (English)

    Full Text Available Hg Morphological trait Panicle/flower RFLP d)Co-segregated F2 RG348 rgn Yu, Z.H., K...inoshita, T., Sato, S., and Tanksley, S.D. (1992). Morphological and RFLP markers are associated in rice. Rice Genetics Newsletter 9, 116-118. ...

  2. Colored HOMFLY polynomials can distinguish mutant knots

    CERN Document Server

    Nawata, Satoshi; Singh, Vivek Kumar

    2015-01-01

    We illustrate from the viewpoint of braiding operations on WZNW conformal blocks how colored HOMFLY polynomials with multiplicity structure can detect mutations. As an example, we explicitly evaluate the (2,1)-colored HOMFLY polynomials that distinguish a famous mutant pair, Kinoshita-Terasaka and Conway knot.

  3. Two improvements to the dynamic wake meandering model: including the effects of atmospheric shear on wake turbulence and incorporating turbulence build-up in a row of wind turbines

    DEFF Research Database (Denmark)

    Keck, Rolf-Erik; de Mare, Martin Tobias; Churchfield, Matthew J.

    2015-01-01

    the model to simulate the build-up of turbulence over a row of turbines in a physically consistent manner. The performance of the modified model is validated against actuator line (AL) model results and field data from the Lillgrund offshore wind farm. Qualitatively, the modified DWM model is in fair......%, respectively, by including the proposed corrections for a row of eight turbines. Furthermore, it is found that the root-mean-square difference between the AL model and the modified DWM model in terms of wind speed and turbulence intensity does not increase over a row of turbines compared with the root...

  4. Radar facies and architecture of alluvial fans and related sediments in high-energy alpine environments, British Columbia

    Science.gov (United States)

    Ekes, Csaba

    2000-08-01

    It is widely recognized that the dominant depositional processes on alluvial fans include rock falls, rock slides, rock avalanches, debris flows, sheetfloods and incised-channel floods. A fundamental question addressed in this thesis is: Can ground penetrating radar (GPR) differentiate between the sediments associated with these processes? Do these individual deposits have characteristic radar reflection signatures? The dissertation is divided into two parts. In part one, a calibration exercise conducted in southern British Columbia, it was demonstrated that GPR was able to obtain good penetration and resolution in rock fall, rock slide, fluvial and alluvial fan sediments, and that a characteristic radar reflection pattern (or radar facies) can be assigned to these deposits. Bedrock reflection pattern is characterised by a discontinuous radar signal and by stacked diffractions. The radar facies for rock slide and rock avalanche sediments, where boulders constitute the predominant clast size, is characterized by discontinuous, high amplitude, macro-scale, hyperbolic reflections that are different from diffractions generated by bedrock. Alluvial fans dominated by debris flow processes produce a chaotic and discontinuous radar pattern; diffractions in these patterns are attributed to boulders. Alluvial fans dominated by sheetflood processes are likely to produce surface-parallel, gently dipping, more or less continuous radar patterns. Large-scale meandering-river radar-patterns are characterized by high amplitude, continuous, dipping clinoforms. Braided-river radar facies, based on data collected on the Kicking Horse braidplain, are characterized by predominantly horizontally continuous reflections with few identifiable features. Based solely on GPR data, it was possible to distinguish between sediments of meandering and braided rivers. Analysis of over 95 km GPR data suggests that alluvial fan radar-reflection patterns are distinctly different from those observed in

  5. Arrested geomorphic trajectories and the long-term hidden potential for change.

    Science.gov (United States)

    James, L Allan

    2017-11-01

    Geomorphic systems often experience morphological changes that define a trajectory over decadal time periods. These trends can be halted by natural inhibitors such as vegetation, knickpoints, bed armor, or bank cohesion, or by anthropogenic inhibitors such as revetment, levees, or dams. Details about where and how channels and floodplains are stabilized are often poorly understood, which poses a risk that modern projects could unwittingly remove critical stabilizing elements (inhibitors) and unleash an episode of rapid change. The potential for destabilization is particularly keen for rivers that were severely altered by human activities but were stabilized by an inhibitor before readjustment was complete. This study uses aerial photographs to examine two cases of arrested geomorphic trajectories in the lower Yuba and Feather Rivers of northern California after 150 years of severe human disturbance. Channel adjustments were inhibited in distinctly different ways. First, channelization of the Feather River across a high-amplitude meander bend ∼4 km below the Yuba-Feather River confluence resulted in a knickpoint at Shanghai Shoals that retreated upstream at an average rate of 3.67 m/yr from 1963 to 2013 with two episodes of rapid retreat. Shanghai Shoals was breached in 2013. Second, numerous wing dams on the Yuba River constructed in the early nineteenth century limit floodplain widening and prevent return to an anastomosing channel planform. Their stabilizing role is important to preventing mobilization of mining sediment with high concentrations of mercury. These rivers exemplify how arrested geomorphic trajectories may impact sustainable river management, and how recognition of fluvial evolution is essential to sustainable river management. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. ONR (Office of Naval Research) Far East Scientific Information Bulletin. Volume 14, Number 3, July-September 1989

    Science.gov (United States)

    1989-09-01

    Masahiro Yoshimura Tokyo Institute of Technology Preparation of Mullite Kenya Hamano Kanagawa University Ceramics from Kaolin Hiroaki Nakajima and... Kaolin Hiromichi Ichinose Sachiko Furuta Shuji Yoshida Makoto Egashita Nagasaki University Microstructure and Mechanical Teruhiko Kinoshita Tokyo...cutting angle error and they tures, are thought to be less sensitive to can be grown from a congruent melt, but sulphur . they grow only at 2.5 mm/h

  7. Bacterial Genome Adaptation to Niches: Divergence of the Potential Virulence Genes in Three Burkholderia Species of Different Survival Strategies

    Science.gov (United States)

    2005-12-01

    species For comparative genomic analysis with pathogenic Bm and Bp, we produced finished sequence of the closely related nonpathogenic soil bacterium...1999. 11. Godoy D, Randle G, Simpson AJ, Aanensen DM, Pitt TL, Kinoshita R, Spratt BG: Multilocus sequence typing and evolutionary rela- tionships...5223):496-512. 34. Waterman MS: Computer analysis of nucleic acid sequences . Methods Enzymol 1988, 164:765-793. 35. Bateman A, Birney E, Durbin R, Eddy

  8. Tandem Repeat Regions within the Burkholderia pseudomallei Genome and their Application for High-Resolution Genotyping

    Science.gov (United States)

    2007-03-30

    multilocus sequence typing (MLST) [6]. RAPD detects differences in genomes by amplifying segments of unknown DNA. Drawbacks to this technique include the...Australian isolates using MLST exhibited no overlap between sequence types for the two countries [50]. However, phylogenetic analysis of these data...Aanensen DM, Pitt TL, Kinoshita R, Spratt BG: Multilocus sequence typing and evolutionary rela- tionships among the causative agents of melioidosis

  9. Forensic Discrimination of 25 Isolates of Burkholderia mallei

    Science.gov (United States)

    2007-10-01

    size-fractionated, and immobilized DNA fragments with labeled homologous DNA sequences . An advantage of ribotyping is that it enables genetic analysis ...Simpson, A.J.; Aanensen, D.M.; Pitt, T.L.; Kinoshita, R.; Spratt, B.G. Multilocus Sequence Typing and Evolutionary Relationships Among the Causative...isolate were digested with PstI and EcoRI enzymes and probed with an Escherichia coli-derived 18-mer rDNA sequence to identify diagnostic fragments

  10. Monoclonal Antibodies Passively Protect BALB/c Mice Against Burkholderia mallei Aerosol Challenge

    Science.gov (United States)

    2006-03-01

    Kinoshita, and B. G. Spratt. 2003. Multilocus sequence typing and evolu- tionary relationships among the causative agents of melioidosis and glanders...evaluated for statistical significance by linear regression analysis or by analysis of vari- ance. Survival distributions were compared by Kaplan-Meier...determined the antigenic specificity of the four anti-B. mallei MAbs by immunoblot analysis of B. mallei sep- arated by SDS-PAGE with 10 to 20% precast

  11. Pose Determination of a Grasped Object Using Limited Sensing

    Science.gov (United States)

    1991-05-01

    7th International Symposium on Industrial Robots, pages 353-361, Tokyo, October 1977. 174 [50] J. M. Hollerbach. A review of kinematic calibration...118, Tokyo, 1977. [65j G. I. Kinoshita. Representation and tactile sensing of 3-d objects by a gripper finger. Robotica , 1:217-222, 1983. [66] G. I...St. Clair. Conductive elastomers as sensor for industrial parts handling equipment. IEEE Transactions on Instrumentation and Measurement, IM-27:94

  12. Étrange ou ennemi ? Typologie de l’étranger, construction identitaire et circonvolutions du discours dans l’Angleterre des XVIe et XVIIe siècles Monster or Enemy? Types of Strangers, Construction of National Identity, and the Meanderings of Discourse in 16th and 17th century England

    Directory of Open Access Journals (Sweden)

    Michèle Vignaux

    2009-06-01

    Full Text Available Taking Bacon’s and Coke’s definitions of strangers in the Case of the Post-Nati (1605 as a starting point, this article examines the implications of defining English citizens as subjects owing allegiance to the King of England by looking at the various types of allegiance (which may be implicit or explicit, geographically or temporally limited or unlimited. It concludes that the one unbridgeable chasm was with perpetual enemies, that is with infidels, rather than with strangers as such. Ironically, the monstrosities of Mandevillian lore resurfaced with the discovery of the “fourth continent” when in the face of economic “necessity” Christian discourse was trapped into labelling as monstrous, and denying humanity to, those strangers who were to be used as slaves.

  13. 78 FR 8018 - Establishment of the Indiana Uplands Viticultural Area and Modification of the Ohio River Valley...

    Science.gov (United States)

    2013-02-05

    ...) generally easterly to the mouth of French Creek in Franklin Township, Floyd County, Indiana (Louisville map..., approximately 0.3 mile south of the White River; then (6) Proceed easterly along the meandering 200-meter... easterly then southwesterly along the meandering 200- meter contour line, crossing to the Bedford map,...

  14. TOPFARM: Multi-fidelity optimization of wind farms

    DEFF Research Database (Denmark)

    Réthoré, Pierre-Elouan; Fuglsang, Peter; Larsen, Gunner Chr.

    2014-01-01

    on the basis of the interpolation in a database of simulations performed for various wind speeds and wake setups with the aero-elastic code HAWC2 and the dynamic wake meandering model. The third level, not considered in this present paper, includes directly the HAWC2 and the dynamic wake meandering model...

  15. Two-dimensional equilibrium island shape and step free energies of Cu(001)

    NARCIS (Netherlands)

    van Moere, R.; Zandvliet, Henricus J.W.; Poelsema, Bene

    2003-01-01

    We have derived expressions for the free energies of the densely packed [110] and 100% kinked [010] step edges of Cu(001), including both meandering and vibrational entropy terms. The meandering entropy is calculated by taking into account nearest-neighbor and next-nearest-neighbor interactions

  16. A nonlinear theory of the bimodality of the Kuroshio extension

    NARCIS (Netherlands)

    Pierini, S.; Dijkstra, H.A.; Riccio, A.

    2009-01-01

    The Kuroshio Extension (KE) flow in the North Pacific Ocean displays a very distinctive decadal variability of bimodal character involving two completely different states (a large-meander “elongated” state and a small-meander “contracted” state) connected by very asymmetric temporal transitions. Alt

  17. APPLICABILITY OF THE BEND DEVELOPMENT THEORY IN NATURAL ALLUVIAL RIVERS

    Institute of Scientific and Technical Information of China (English)

    M.M.RAHMAN; M.A.HAQUE; M.M.HOQUE

    2002-01-01

    The theoretical conditions for the bend development or attenuation have been reviewed and tested for a study reach of the Meghna river.The field observations in the natural alluvial meander do not support the theories developed for bend development.The limitations of the theory to apply in the natural meandering river are discussed.

  18. Myanmar, Southeast Asia as seen from STS-59

    Science.gov (United States)

    1994-01-01

    View westward from Burma across a finger of India into the Ganges Delta in Bangladesh. The meandering stream in the foreground is the Chindwin River about 100 miles northwest of Mandalay; the stream having tiny meanders is the Myittha; and the stream in sunglint is the Manipur River flowing through the Chin Hills. Extensive hillside fires fill the valleys of Burma with smoke.

  19. Proposal of a new autocorrelation function in low wind speed conditions

    Science.gov (United States)

    Moor, L. P.; Degrazia, G. A.; Stefanello, M. B.; Mortarini, L.; Acevedo, O. C.; Maldaner, S.; Szinvelski, C. R. P.; Roberti, D. R.; Buligon, L.; Anfossi, D.

    2015-11-01

    In this study a new mathematical expression to describe the observed meandering autocorrelation functions in low-wind speed is proposed. The analysis utilizes a large number of best fit curves to show that the proposed theoretical function well reproduces the general form and the negative lobes characterizing the experimental meandering autocorrelation function. Further, the good agreement of the measured autocorrelation curves with the proposed algebraic autocorrelation function allows to calculate the magnitudes of the meandering period and of the loop parameter. The results agree with the values presented and discussed in the literature. Therefore, the new formulation describing experimental meandering autocorrelation functions can be used to simulate the dispersion of contaminant during low wind episodes and to determine relevant meandering parameters.

  20. Oscillations in the hadron scattering amplitude at high energy and small momentum transfer; Oscillations dans l`amplitude de diffusion hadronique a haute energie et petites moments de transfer

    Energy Technology Data Exchange (ETDEWEB)

    Gauron, Pierre; Basarab Nicolescu [Theoretical Physics Division, Inst. de Physique Nucleaire, Paris-11 Univ., 91 - Orsay (France); Selyugin, O.V. [Lab. of Theoretical Physics, Joint Inst. for Nuclear Research, Dubna (Russian Federation)

    1999-10-01

    We show that the high precision dN/dt UA4/2 data at {radical} = 541 GeV are compatible with the presence of Auberson-Kinoshita-Martin (AKM) type of oscillations at very small momentum transfer. These oscillations seem to be periodic in {radical}|t|, the corresponding period being {approx_equal} 2 {center_dot}10{sup -2} GeV. The existence of such visible oscillations suggests a general mechanism of saturation of axiomatic bounds. As an illustration the consequences for extracting the parameter {rho} = ReF/ImF from dN/dt data are also discussed. (authors) 1 ref., 2 figs.

  1. Quench Dynamics in Confined 1+1-Dimensional Systems

    CERN Document Server

    Engelhardt, Dalit

    2015-01-01

    We present a scheme for investigating the response of confined 1+1-dimensional systems to a quantum quench and consider the extent to which a system whose post-quench dynamics are near-integrable may be analyzed by an application of boundary CFT techniques. As the main example we present a model of a split-momentum quench in a finite 1D geometry, a setup analogous to that of the experiment of Kinoshita, Wenger, and Weiss [Nature 440, 900 (2006)]. We analytically derive the form of the expected momentum distributions and describe how such information may be used to assess the extent of integrability breaking in realistic systems.

  2. FLUID EXCHANGE ACROSS THE EQUATORIAL FRONT

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, the cusp-shaped wave pattern (Legeckis wave) along the Equatorial Front (EF) is modeled by a meandering jet, and the motion of fluid parcels in a two-dimensional kinematic model of the meandering jet along EF is studied using Melnikov's method. Results indicated that the velocity field of the cusp-shaped wave pattern can indeed be modeled by a meandering jet; that the EF will act as a barrier to fluid exchange if there is no variability, but that it is just the variability that moves the buoy across the EF.

  3. FLUID EXCHANGE ACROSS THE EQUATORIAL FRONT

    Institute of Scientific and Technical Information of China (English)

    姜传丽; 吕建; 吴德星

    2001-01-01

    In this paper, the cusp-shaped wave pattern (Legeckis wave) along the Equatorial Front (EF) is modeled by a meandering jet, and the motion of fluid parcels in a two-dimensional kine-matic model of the meandering jet along EF is studied using Melnikov's method. Results indicated that the velocity field of the cusp-shaped wave pattern can indeed be modeled by a meandering jet; that the EF will act as a barrier to fluid exchange if there is no variability, but that it is just the variability that moves the buoy across the EF.

  4. Fabrication of a 3D electrically small antenna using holographic photolithography

    Science.gov (United States)

    Toriz-Garcia, J. J.; Cowling, J. J.; Williams, G. L.; Bai, Q.; Seed, N. L.; Tennant, A.; McWilliam, R.; Purvis, A.; Soulard, F. B.; Ivey, P. A.

    2013-05-01

    We describe the novel fabrication of a 3D electrical small antenna and its subsequent characterization. The patterning of meander lines conformed onto a hemispherical substrate is achieved by 3D holographic photolithography, which uses time-division multiplexing of a series of iteratively optimized computer-generated holograms. The meander lines have a line width of 100 µm and line separation of 400 µm, with a line pitch of 500 µm and a total meander length of 145 mm. The working frequency is found to be 2.06 GHz, with an efficiency of 46%. This work demonstrates a new method for the fabrication of 3D conformal antennas.

  5. Reconsidered estimates of the 10th order QED contributions to the muon anomaly

    CERN Document Server

    Kataev, A L

    2006-01-01

    The problem of estimating the 10th order QED corrections to the muon anomalous magnetic moment is reconsidered. The incorporation of the recently improved contributions to the $\\alpha^4$ and $\\alpha^5$- corrections to $a_{\\mu}$ within the renormalization-group inspired scheme-invariant approach leads to the estimate $a_{\\mu}^{(10)}\\approx 643$. It is in good agreement with the estimate $a_{\\mu}^{(10)}= 663(20) (\\alpha/\\pi)^5$, obtained by Kinoshita and Nio from the numerical calculations of 2958 10-th order diagrams, which are considered to be more important than the still uncalculated 6122 10th-order $m_{\\mu}/m_e$-dependent vertex graphs, and 12672 5-loop diagrams, responsible for the mass-independent constant contribution both to $a_{\\mu}$ and $a_e$. This confirms Kinoshita and Nio guess about dominance of the 10-th order diagrams calculated by them. Comparisons with other estimates of the $\\alpha^5$- contributions to $a_{\\mu}$, which exist in the literature, are presented.

  6. Effects of Cu Layer Width on the Giant Magneto-impedance Effect in Sandwich FeCuNbCrSiB/Cu/FeCuNbCrSiB Films With a Meander Line Structure%Cu层宽度对弯曲型三明治结构FeCuNbCrSiB/Cu/FeCuNbCrSiB多层膜巨磁阻抗效应的影响

    Institute of Scientific and Technical Information of China (English)

    张亚民; 陈吉安; 周勇; 丁文; 王明军; 高孝裕; 周志敏

    2005-01-01

    采用射频磁控溅射方法和微细加工工艺制备了不同Cu层宽度的弯曲型三明治结构的FeCuNbCrSiB/Cu/FeCuNbCrSiB多层膜,在频率1~40MHz下研究了Cu层宽度对多层膜的纵向和横向巨磁阻抗效应的影响.结果表明,弯曲型三明治结构多层膜的巨磁阻抗率随Cu层宽度的变化具有显著的变化,在频率10MHz、磁场12kA/m下,当Cu层宽度为0.4mm时,纵向、横向巨磁阻抗率分别达-57%、-65%.

  7. Shaded Relief of the Bathymetry near Shorty's Island and Myrtle Bend, 2010, Kootenai River near Bonners Ferry, ID

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The shaded relief raster data was created based on bathymetry obtained in the meander reach collected in about a one month period extending from 6/3/2010 -...

  8. River Corridors (Jan 2, 2015)

    Data.gov (United States)

    Vermont Center for Geographic Information — River corridors are delineated to provide for the least erosive meandering and floodplain geometry toward which a river will evolve over time. River corridor maps...

  9. 27 CFR 9.184 - Trinity Lakes.

    Science.gov (United States)

    2010-04-01

    ... the meandering contour line across Van Ness Creek, both Bear Gulches, Langdon Gulch, Digger Gulch... to the southeast corner of section 1, R9W/T34N, near Smith Gulch; (31) Continue due west along the...

  10. Altered River Morphology in South Africa Related to the Permian-Triassic Extinction

    National Research Council Canada - National Science Library

    Peter D. Ward; David R. Montgomery; Roger Smith

    2000-01-01

    The Permian-Triassic transition in the Karoo Basin of South Africa was characterized by a rapid and apparently basin-wide change from meandering to braided river systems, as evidenced by preserved sedimentary facies...

  11. In the past two decades, research interest has focused on the eddy ...

    African Journals Online (AJOL)

    spamer

    Current results in meandering, with the formation of eddies that can ... forced by a number of oceanic and meteorological boundary conditions, none of which is entirely predictable. ...... invade the South Atlantic: evidence from Geosat altimeter.

  12. Novel Electrically Small Spherical Electric Dipole Antenna

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.

    2010-01-01

    of 72 ohms is numerically investigated and its performance is compared to that of the multiarm spherical helix antenna of the same size. Both antennas yield equal quality factors, which are about 1.5 times the Chu lower bound, but quite different cross-polarization characteristics.......This paper introduces a novel electrically small spherical meander antenna. Horizontal sections of the meander are composed of wire loops, radii of which are chosen so that the whole structure is conformal to a sphere of radius a. To form the meander the loops are connected by wires at a meridian...... plane. The antenna operates as an electric dipole, i.e. it radiates the TM10 spherical mode. The antenna is self-resonant and can be matched to a wide range of input feed lines without an external matching network. In this paper, a spherical meander antenna of the size ka = 0.27 and the input impedance...

  13. The impact of reduced conductivity on the performance of wire antennas

    CERN Document Server

    Shahpari, Morteza

    2015-01-01

    Low cost methods of antenna production primarily aim to reduce the cost of metalization. This might lead to a reduction in conductivity. A systematic study on the impact of conductivity is presented. The efficiency, gain and bandwidth of cylindrical wire meander line, dipole, and Yagi-Uda antennas were compared for materials with conductivities in the range $\\mathrm{10^3}$ to $\\mathrm{10^9}$ S/m. In this range, the absorption efficiency of both the dipole and meander line changed little, however the conductivity significantly impacts on radiation efficiency and the absorption cross section of the antennas. The extinction cross section of the dipole and meander line antennas (antennas that Thevenin equivalent circuit is applicable) also vary with radiation efficiency. From the point of radiation efficiency, the dipole antenna performance is most robust under decreasing conductivity. The power to volume ratio reveals that the meander line antenna is more economical than dipole and Yagi antennas in terms of cost...

  14. Downstream-migrating fluvial point bars in the rock record

    Science.gov (United States)

    Ghinassi, Massimiliano; Ielpi, Alessandro; Aldinucci, Mauro; Fustic, Milovan

    2016-04-01

    Classical models developed for ancient fluvial point bars are based on the assumption that meander bends invariably increase their radius as meander-bend apices migrate in a direction transverse to the channel-belt axis (i.e., meander bend expansion). However, many modern meandering rivers are also characterized by down-valley migration of the bend apex, a mechanism that takes place without a significant change in meander radius and wavelength. Downstream-migrating fluvial point bars (DMFPB) are the dominant architectural element of these types of meander belts. Yet they are poorly known from ancient fluvial-channel belts, since their disambiguation from expansional point bars often requires fully-3D perspectives. This study aims to review DMFPB deposits spanning in age from Devonian to Holocene, and to discuss their main architectural and sedimentological features from published outcrop, borehole and 3D-seismic datasets. Fluvial successions hosting DMFPB mainly accumulated in low accommodation conditions, where channel belts were affected by different degrees of morphological (e.g., valleys) or tectonic (e.g., axial drainage of shortening basins) confinement. In confined settings, bends migrate downstream along the erosion-resistant valley flanks and little or no floodplain deposits are preserved. Progressive floor aggradation (e.g., valley filling) allow meander belts with DMFPB to decrease their degree of confinement. In less confined settings, meander bends migrate downstream mainly after impinging against older, erosion-resistant channel fill mud. By contrast, tectonic confinement is commonly associated with uplifted alluvial plains that prevented meander-bend expansion, in turn triggering downstream translation. At the scale of individual point bars, translational morphodynamics promote the preservation of downstream-bar deposits, whereas the coarser-grained upstream and central beds are less frequently preserved. However, enhanced preservation of upstream

  15. A study of hydro-graphene for energy storage (2) hydrogen absorption

    Energy Technology Data Exchange (ETDEWEB)

    Tokio, Yamabe; Mitsuhiro, Fujii [Nagasaki Institute of Applied Science, Nagasaki (Japan); Yoshio, Furuya [Faculty of Education, Dept. of Technology, Nagasaki (Japan); Shiro, Mori; Shizukuni, Yata [Energy Conversion Research Lab., KRI Inc., Kyoto (Japan)

    2005-07-01

    The technology of hydrogen storage is one of the most important challenges in hydrogen energy system for clean environment [1]. Some carbon materials are expected to have such advantage for hydrogen storage. We have studied about PAS and PAHs, which are marginal members of the carbon allotropes containing a significant amount of hydrogen atoms, and which show a variety of interesting properties lacking pure carbon materials [2-9]. They constituted by graphite sheets terminated by hydrogen atoms, and so it may be called 'hydro-graphene' [10]. In this work, we prepared two kinds of hydro-graphene, such as PAS [8,9] and PAHs [7], by the pyrolysis at 550 C. The [H]/[C] molar ratio of PAS was 0.45, and that of PAHs was 0.33. The interlayer distance of PAS was broad, and that of PAH was 3.68 A. We examined their ability of hydrogen storage by two methods. It was measured the amount of equilibrium pressure change of sample room, on the first method of increasing hydrogen pressure at 77 K, and on the second method of temperature increasing to R.T. in vacuum after reducing pressure. On the former method, the hydrogen storage amount of PAS was 0.5 wt-%, and that of PAHs was about 0.4 wt-%. On the latter, that of PAS was 0.4 wt-%, d that of PAHs was 0.3 wt-%. Those results indicate that each total capacity of hydrogen storage was estimated 0.5-0.6 wt%. We will discuss the mechanism of hydrogen adsorption to hydro-graphene based on the quantum chemical viewpoint. [1] DOE Hydrogen Program: www.hydrogen.energy.gov. [2] P. Novac, K. Muller, K. S. V. Santhanam, O. Haas: Chem. Rev., 97, 270, 1997; [3] T. Yamabe, K. Tanaka, K. Ohzeki, S. Yata: Solid State Commun., 44, 823, 1982; [4] S. Yata, Y. Hato, K. Sakurai, H. Satake, K. Mukai, K. Tanaka, T. Yamabe: Synth. Met., 38, 169, 1990; [5] S. Yata, H. Kinoshita, M. Komori, N. Ando, T. Kashiwamura, T. Harada, K Tanaka, T. Yamabe: Synth. Met., 62, 153, 1994; [6] J. R. Dahn, T. Zheng, Y. Liu, J. S. Xue: Science, 270, 590, 1995

  16. 76 FR 35346 - Airworthiness Directives; Eurocopter France Model SA-365C, SA-365C1, SA-365C2, SA-365N, SA-365N1...

    Science.gov (United States)

    2011-06-17

    ... high amplitude vibrations in flight, compelling the pilot to make a precautionary landing. The actions... two of these cases, the deterioration caused high amplitude vibrations in flight, compelling the pilot...-amplitude vibrations could make it difficult to control the helicopter. Related Service...

  17. High speed, high current pulsed driver circuit

    Energy Technology Data Exchange (ETDEWEB)

    Carlen, Christopher R.

    2017-03-21

    Various technologies presented herein relate to driving a LED such that the LED emits short duration pulses of light. This is accomplished by driving the LED with short duration, high amplitude current pulses. When the LED is driven by short duration, high amplitude current pulses, the LED emits light at a greater amplitude compared to when the LED is driven by continuous wave current.

  18. Interface characteristics of the Third and Fourth Members of Denglouku Formation in deep Changde gas field, Songliao Basin%松辽盆地昌德气田深层登三、四段底界面特征

    Institute of Scientific and Technical Information of China (English)

    张艳; 孙雅林; 王璞珺; 吴艳辉; 姚瑞士; 瞿雪娇

    2011-01-01

    The Third and Fourth Members of Denglouku Formation (K,d3 and K1d4) are the important gas productive reservoirs in Changde gas field, Songliao Basin. However, the interfaces of K1d3 and K1d4 have been confused in definition before, which impeded the oil and gas exploration. The authors studied the characteristics of K1d3, K1d4 and key interface by lithological, logging and seismic analyses, and adjusted the defination of the interfaces based on their characteristics. Lithologically, the K1d3 and K1 d4 mainly are composed of mudstone, developing lacustrine and meandering river facies. In the K, d3, the resistivity curve presents high frequency, medium-high amplitude, and finger or box shape. The base surface of K1d3 is the bottom boundary of sandstone and top boundary of mudstone, and the gamma ray curve shows negative step shaped, while the elective resistance shows positive step shaped with onlap and toplap characteristics in seismic profile. In the K1d4, the resistivity curve presents medium-high frequency, medium amplitude, finger and box interbed shape. The base surface of K1d4 is the bottom boundary of mudstone and top boundary of sandstone, and the gamma ray curve shows positive step shaped, while the elective resistance shows negative step shaped with concordance characteristics in seismic profile. Thus,the definition on the imferfaces of 12 wells in the bottom of K1d3 and 8 wells in the bottom of K1d4 were adjusted.%松辽盆地昌德气田登娄库组三、四段是深层主要产气层位,但井震地层界面不一致阻碍了该区油气勘探.从岩性、测井和地震等方面对登三、四段主要特征及关键界面特征进行综合研究,荻取各段界面主要特征,并据此进行了对界面确定的调整.登三、四段岩性以泥岩为主,发育湖相和曲流河相.登三段电阻曲线呈高频中高幅指状或箱型,底面为一套砂岩组底界,泥岩组顶面,GR负台阶,电阻正台阶,地震剖面上具有上超和顶超的

  19. Shallow Faulting in Morelia, Mexico, Based on Seismic Tomography and Geodetically Detected Land Subsidence

    Science.gov (United States)

    Cabral-Cano, E.; Arciniega-Ceballos, A.; Vergara-Huerta, F.; Chaussard, E.; Wdowinski, S.; DeMets, C.; Salazar-Tlaczani, L.

    2013-12-01

    include secondary faults at depths up to 4-8m below the surface and located up to 24m away from the main fault trace. The Torremolinos fault system includes secondary faults, which are present up to 8m deep and 12-18m away from the main fault trace. Even though the InSAR analysis provides an unsurpassed synoptic view, a higher temporal resolution observation of fault movement has been pursued using the MOIT continuously operating GPS station, which is located within 100 m from the La Colina main fault trace. GPS data is also particularly useful to decompose horizontal and vertical motion in the absence of both ascending and descending SAR data acquisitions. Observations since July 2009 show a total general displacement trend of -39mm/yr and a total horizontal differential motion of 41.8 mm/yr and -4.7mm/yr in its latitudinal and Longitudinal components respectively in respect to the motion observed at the MOGA GPS station located 5.0 km to the SSE within an area which is not affected by subsidence. In addition to the overall trend, high amplitude excursions at the MOIT station with individual residual amplitudes up to 20mm, 25mm, and 60mm in its latitudinal, longitudinal and vertical components respectively vertical are observed. The correlation of fault motion excursions in relationship to the rainfall records will be analyzed.

  20. Trialing a new clinical clerkship record in Japanese clinical training

    Directory of Open Access Journals (Sweden)

    Nomura S

    2015-09-01

    Full Text Available Shosaku Nomura, Noboru Tanigawa, Yo Kinoshita, Koichi TomodaFirst Department of Internal Medicine, Kansai Medical University, Shinmachi, Hirakata, Osaka, JapanUndergraduate medical education has several problems.1,2 In particular, clinical training, which is the unique feature of medical education, tends to be performed less extensively. In Japan, the current clinical training method is clinical clerkship (CC. CC differs from conventional clinical training, which is study by observation. In CC, the student is a member of the medical team and participates in actual medical care. The student is allowed to practice medical actions in the definite range under the guidance and monitoring of a teaching doctor. Therefore, students can acquire practical clinical abilities. In their study of medical care, students are required to have their own sense of identity and personal responsibility. Clinical training is performed by CC following the original curriculum for diagnoses and treatments in various medical departments.

  1. Task-Dependent Masked Priming Effects in Visual Word Recognition

    Science.gov (United States)

    Kinoshita, Sachiko; Norris, Dennis

    2012-01-01

    A method used widely to study the first 250 ms of visual word recognition is masked priming: These studies have yielded a rich set of data concerning the processes involved in recognizing letters and words. In these studies, there is an implicit assumption that the early processes in word recognition tapped by masked priming are automatic, and masked priming effects should therefore be invariant across tasks. Contrary to this assumption, masked priming effects are modulated by the task goal: For example, only word targets show priming in the lexical decision task, but both words and non-words do in the same-different task; semantic priming effects are generally weak in the lexical decision task but are robust in the semantic categorization task. We explain how such task dependence arises within the Bayesian Reader account of masked priming (Norris and Kinoshita, 2008), and how the task dissociations can be used to understand the early processes in lexical access. PMID:22675316

  2. Task-dependent masked priming effects in visual word recognition.

    Science.gov (United States)

    Kinoshita, Sachiko; Norris, Dennis

    2012-01-01

    A method used widely to study the first 250 ms of visual word recognition is masked priming: These studies have yielded a rich set of data concerning the processes involved in recognizing letters and words. In these studies, there is an implicit assumption that the early processes in word recognition tapped by masked priming are automatic, and masked priming effects should therefore be invariant across tasks. Contrary to this assumption, masked priming effects are modulated by the task goal: For example, only word targets show priming in the lexical decision task, but both words and non-words do in the same-different task; semantic priming effects are generally weak in the lexical decision task but are robust in the semantic categorization task. We explain how such task dependence arises within the Bayesian Reader account of masked priming (Norris and Kinoshita, 2008), and how the task dissociations can be used to understand the early processes in lexical access.

  3. Coupled cluster method with single and double excitations tailored by matrix product state wave functions

    CERN Document Server

    Veis, Libor; Neese, Frank; Legeza, Örs; Pittner, Jiří

    2016-01-01

    We present an alternative method for accurate treatment of strongly correlated systems which combines the coupled cluster (CC) theory with the density matrix renormalization group method (DMRG). The connection is done in the spirit of the tailored CC method [T. Kinoshita, O. Hino, and R. J. Bartlett, \\textit{J. Chem. Phys.} {\\bf 123} (2005) 074106]. In the first step, the configuration interaction (CI) coefficients corresponding to single and double excitations within the DMRG active space are computed by contraction of the matrix product state (MPS) matrices. These coefficients are subsequently transformed into CC amplitudes. In the second step, the CC amplitudes are used to define a "tailored" single reference CCSD wavefunction. As a result, the DMRG method is responsible for the proper description of non-dynamic correlation, whereas the dynamic correlation is incorporated through the framework of the CC theory. We illustrate the potential of this method on prominent multireference model systems like N$_2$ ...

  4. Three-loop QED vacuum polarization and the four-loop muon anomalous magnetic moment

    CERN Document Server

    Baikov, P A

    1995-01-01

    Three--loop contributions to massive QED vacuum polarization are evaluated by a combination of analytical and numerical techniques. The first three Taylor coefficients, at small q^2, are obtained analytically, using d\\/--dimensional recurrence relations. Combining these with analytical input at threshold, and at large q^2, an accurate Pad\\'e approximation is obtained, for all q^2. Inserting this in the one--loop diagram for the muon anomalous magnetic moment, we find reasonable agreement with four--loop, single--electron--loop, muon--anomaly contributions, recently re--evaluated by Kinoshita, using 8--dimensional Monte--Carlo integration. We believe that our new method is at least two orders of magnitude more accurate than the Monte--Carlo approach, whose uncertainties appear to have been underestimated, by a factor of 6.

  5. Warped branches of flux compactifications

    CERN Document Server

    Lim, Yen-Kheng

    2012-01-01

    We consider Freund-Rubin-type compactifications which are described by (p+q)-dimensional Einstein gravity with a positive cosmological constant and a q-form flux. Using perturbative expansions of Kinoshita's ansatz for warped dS_pxS^q and AdS_pxS^q spacetimes, we obtain analytical solutions describing the warped branches and their respective phase spaces. These equations are given by inhomogeneous Gegenbauer differential equations which can be solved by the Green's function method. The requirement that the Green's functions are regular provides constraints which determine the structure of the phase space of the warped branches. We apply the perturbation results to calculate the thermodynamic variables for the warped dS_pxS^q branch. In particular, the first law of thermodynamics can be reproduced using this method.

  6. "US-JAPAN CONFERENCE: INFLAMMATION, DIABETES AND CANCER" held at the Beckman Research Institute of City of Hope, Duarte, CA, USA.

    Science.gov (United States)

    Fujita-Yamaguchi, Yoko; Lin, Ren-Jang; Jove, Richard

    2011-12-01

    The conference was held to facilitate research collaborations between US and Japan scientists, and to commemorate the rich history of the Beckman Research Institute of City of Hope (COH) research contributed by many Japanese doctors. Most noticeable is Dr. Ryojun Kinoshita, an internationally renowned oncologist who built the first research team at the campus of COH Medical Center in 1952. The conference received enthusiastic support from Junichi Ihara, Consul General of Japan, Los Angeles. During the two day conference, seven scientists from Japan, six scientists from Southern California, and six scientists from COH presented various aspects of cancer and diabetes research which included nuclear receptor regulation, DNA base and chromatin modifications, cancer glycosylation, circadian clock, cell polarity, tumorigenesis, micro and small RNA therapies, genomics, epigenetics, and signaling.

  7. Bridging single and multireference coupled cluster theories with universal state selective formalism.

    Science.gov (United States)

    Bhaskaran-Nair, Kiran; Kowalski, Karol

    2013-05-28

    The universal state selective (USS) multireference approach is used to construct new energy functionals which offer a possibility of bridging single and multireference coupled cluster theories (SR/MRCC). These functionals, which can be used to develop iterative and non-iterative approaches, utilize a special form of the trial wavefunctions, which assure additive separability (or size-consistency) of the USS energies in the non-interacting subsystem limit. When the USS formalism is combined with approximate SRCC theories, the resulting formalism can be viewed as a size-consistent version of the method of moments of coupled cluster equations employing a MRCC trial wavefunction. Special cases of the USS formulations, which utilize single reference state specific CC [V. V. Ivanov, D. I. Lyakh, and L. Adamowicz, Phys. Chem. Chem. Phys. 11, 2355 (2009)] and tailored CC [T. Kinoshita, O. Hino, and R. J. Bartlett, J. Chem. Phys. 123, 074106 (2005)] expansions are also discussed.

  8. Half-lives of $\\alpha$ decay from natural nuclides and from superheavy elements

    CERN Document Server

    Qian, Yibin

    2014-01-01

    Recently, experimental researches on the $\\alpha$ decay with long lifetime are one of hot topics in the contemporary nuclear physics [e.g. N. Kinoshita {\\sl et al.} (2012) and J. W. Beeman {\\sl et al.} (2012) ]. In this study, we have systematically investigated the extremely long-lived $\\alpha$-decaying nuclei within a generalized density-dependent cluster model involving the experimental nuclear charge radii. In detail, the important density distribution of daughter nuclei is deduced from the corresponding experimental charge radii, leading to an improved $\\alpha$-core potential in the quantum tunneling calculation of $\\alpha$-decay width. Besides the excellent agreement between theory and experiment, predictions on half-lives of possible candidates for natural $\\alpha$ emitters are made for future experimental detections. In addition, the recently confirmed $\\alpha$-decay chain from $^{294}$117 is well described, including the attractive long-lived $\\alpha$-decaying $^{270}$Db, i.e., a positive step toward...

  9. Generation of deep eddies by a turning baroclinic jet

    Science.gov (United States)

    Sutyrin, Georgi

    2015-07-01

    The North Atlantic Current (NAC) travels northward east of the Grand Banks until approximately 50°N where it makes a sharp turn to the east. Previous analysis of sea level variability in this region, known as the Northwest Corner, showed large-amplitude meandering and a quasi-regular production of anticyclonic eddies playing an important role in the air-sea heat exchange. Here we investigate key physical mechanisms of meandering of an idealized upper ocean turning jet using a two-layer model. The existing reduced-gravity thin jet theory is modified to take into account the crossjet velocity in the lower layer induced by the jet meanders. Such coupled system is capable to describe realistically baroclinic instability and to reduce the two-dimensional initial value problem to a rather simple one-dimensional formulation. Its linearized version is solved here to describe the fluid motion in both layers in terms of jet curvature. It is found that transient meander growth is enhanced in the vicinity of turning point owing to vertical coupling with deep eddies generated due to stretching in water column beneath growing meanders. Scaling for initial growth of deep cyclone-anticyclone pair is suggested based on a generalized thin jet theory. Patterns of further nonlinear evolution resembling observational data are described.

  10. Abundância do zooplâncton em diferentes zonas (pelágica e litorânea e horários (manhã e noite em dois lagos meândricos amazônicos - DOI: 10.4025/actascibiolsci.v25i2.2011 Abundance of zooplankton from different zones (pelagic and littoral and time periods (morning and night in two Amazonian meandering lakes - DOI: 10.4025/actascibiolsci.v25i2.2011

    Directory of Open Access Journals (Sweden)

    Erlei Cassiano Keppeler

    2003-04-01

    Full Text Available Durante 10 meses foi estudada a abundância do zooplâncton em dois lagos da Amazônia Sul-Ocidental, situados respectivamente nas coordenadas 10°02'36''S; 67°50'24''W (Lago Amapá e 9°27'21"S; 67°31'39"W (Lago Pirapora. Ambos os lagos caracterizam-se como de meandro abandonado. O objetivo desse estudo foi comparar as regiões pelágica e litorânea, com base na abundäncia da comunidade zooplanctönica, bem como observar diferenças da distribuição dessa comunidade na coluna da água no período da manhã e noite. As coletas foram realizadas com filtragem em rede de zooplâncton (55µm e posterior passagem em garrafa de Van Dorn de 5L. Coletou-se 4L na superfície e 5L nas camadas do meio e fundo, totalizando 14L de água para cada estação de coleta. Adicionalmente, foram medidos parâmetros físicos e químicos como transparência, temperatura, pH, oxigênio dissolvido, condutividade elétrica e turbidez. Anova (análise de variância e teste de Tukey foram usados. Não houve diferença estatística significativa nem para as regiões estudadas como também para os diferentes horários observados. Os resultados dos coeficientes de correlação de Pearson (p Moina spp. (representados por Moina minuta e Moina reticulata e Ceriodaphnia reticulata. Daphnia gessneri também apresentou correlação com ChaoboridaeThe abundance of zooplankton in two lakes of Southwest Amazonia was studied for 10 months in different regions and at different periods of the day. The lakes were Lago Amapá, located at 10°02'36''S, 67°50'24''W, and Lago Pirapora, at 9°27'21"S, 67°31'39". Both lakes are characterized as oxbow lakes. The aim of this study was to compare the pelagic and littoral regions, as well as to determine differences in the distribution of zooplankton in the water column in the morning and at night. Collections were made by filtering water through a 55µm zooplankton net into a 5L Van Dorn bottle, collecting 4L from the top and 5L from the middle and bottom layers, totaling 14L of water for each sampling location. In addition, physical and chemical parameters were measured, including transparency, temperature, pH, dissolved oxygen, electrical conductivity and turbidity. Anova (analysis of variance and Tukey’s test were used. There was no statistically significant difference between the regions studied, nor between the two time periods examined. The results of the Pearson correlation (p Moina spp. (represented by M. minuta and M. reticulate and Ceriodaphnia cornuta, and that Daphnia gessneri was associated with Chaoboridae

  11. Broadband electromagnetic characterization of a 100  Ω traveling-wave electrode by measuring scattering parameters

    Directory of Open Access Journals (Sweden)

    Fabrizio Consoli

    2013-07-01

    Full Text Available The Single Bunch Selector (SBS will be used on the Spiral2 linear accelerator to reduce the rate of high energy bunches reaching the target with, in principle, no residual particles from the suppressed bunches. For this purpose, a pulsed electromagnetic wave will travel along the 100  Ω microstrip meander line electrode of the SBS. In this work we describe the broadband accurate characterization of the electrode electromagnetic features. The method applied here leads to the analytical determination of complex characteristic impedance, propagation constant, and group velocity from a measurement of the 50  Ω scattering parameters on the meander transmission line. Particular care is given to the de-embedding phase of the transitions required to connect the meander electrode to the measurement device.

  12. Chaotic mixing and fractals in a geophysical jet current

    CERN Document Server

    Budyansky, M V; 10.1016/j.cnsns.2006.05.004

    2012-01-01

    We model Lagrangian lateral mixing and transport of passive scalars in meandering oceanic jet currents by two-dimensional advection equations with a kinematic stream function with a time-dependent amplitude of a meander imposed. The advection in such a model is known to be chaotic in a wide range of the meander's characteristics. We study chaotic transport in a stochastic layer and show that it is anomalous. The geometry of mixing is examined and shown to be fractal-like. The scattering characteristics (trapping time of advected particles and the number of their rotations around elliptical points) are found to have a hierarchical fractal structure as functions of initial particle's positions. A correspondence between the evolution of material lines in the flow and elements of the fractal is established.

  13. Thermal vertical bimorph actuators and their applications

    CERN Document Server

    Sehr, H J

    2002-01-01

    In this thesis, a novel concept for lateral actuators based on vertical bimorphs is presented. Vertical bimorphs consist of silicon beams side-coated with aluminium, which bend when heated due to the different thermal expansion coefficients of the two materials causing a displacement in the wafer plane. The heating of the actuator is provided by an electrical current through the silicon beam. The simplest implementation of a vertical bimorph actuator is a clamped-clamped beam. To obtain higher deflections, a meander shaped actuator has been designed. By combining four meander actuators, a two-dimensional positioning stage has been realised. The meander actuator has also been applied for normally closed and normally open micro-relays. Analytical calculations and ANSYS simulations have been carried out to predict the physical behaviour of the bimorph devices, including temperature distribution, static deflection, vertical stiffness, thermal time constant and lateral resonances. For both the clamped-clamped beam...

  14. Light detection and ranging measurements of wake dynamics Part I: One-dimensional Scanning

    DEFF Research Database (Denmark)

    Bingöl, Ferhat; Mann, Jakob; Larsen, Gunner Chr.

    2010-01-01

    at the same time widens gradually, primarily because of mixing caused by small-scale atmospheric eddies. In this first paper, we focus on our new measurement technique, and test if the wake meandering follows the wind direction fluctuations, i.e. if it is advected passively in the lateral direction......The vast majority of wind turbines are today erected in wind farms. As a consequence, wake-generated loads are becoming more and more important. In this first of two parts, we present a new experimental technique to measure the instantaneous wake deficit directly, thus allowing for quantification...... of the wake meandering, as well as the instantaneous wake expansion expressed in a meandering frame of reference. The experiment was conducted primarily to test the simple hypothesis that the wake deficit is advected passively by the larger-than-rotor-size eddies in the atmospheric flow, and that the wake...

  15. Developments of the offshore wind turbine wake model Fuga

    DEFF Research Database (Denmark)

    Ott, Søren; Nielsen, Morten

    's Offshore Wind Accelerator Stage 1 project called Linearized CFD Wake models. The earlier project resulted in the development, implementation and validation of the Fuga model. Fuga is a linearized CFD model that can predict wake effects for offshore wind farms. The main purpose of Stage 2 is to add more...... with the modified equations. - Meandering. Meandering has been included in the form of a post processing of the model results that bend and twist the wake centreline. The meandering centrelines are calculated using a Gaussian process developed on the basis of measured spectra. An analysis of meteorological data......This is the final report of the project entitled Risø DTU Modelling Services carried out by DTU Wind Energy (formerly known as Risø National Laboratory) as part of the Carbon Trust's Offshore Wind Accelerator Stage 2 under a contract with Carbon Trust. The project is a follow-up to a Carbon Trust...

  16. VizieR Online Data Catalog: OGLE-III SMC massive stars VI light curves (Kourniotis+, 2014)

    Science.gov (United States)

    Kourniotis, M.; Bonanos, A. Z.; Soszynski, I.; Poleski, R.; Krikelis, G.; Udalski, A.; Szymanski, M. K.; Kubiak, M.; Pietrzynski, G.; Wyrzykowski, L.; Ulaczyk, K.; Kozlowski, S.; Pietrukowicz, P.

    2014-01-01

    We used the photometry provided by the OGLE-III monitoring survey to study the variability of 4646 massive stars with known spectral types in the SMC. Based on the standard deviation of the light curves, we classified the stars into constant, low-amplitude and high amplitude variables. We searched the low- and high-amplitude variables for periodic signals using the Analysis of Variance method (Schwarzenberg-Czerny, 1989MNRAS.241..153S). The following tables present newly discovered and known EBs, ellipsoidal variables, Cepheids and other periodic stars. We also present the irregular variables, which have stochastic, high-amplitude variability. (12 data files).

  17. Challenges in wind farm optimization

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.

    for the wind turbine modeling, where aeroelastic models are required, and for the wind farm flow field description, where in-stationary flow field modeling is needed to capture the complicated mixture of atmospheric boundary layer (ABL) flows and upstream emitted meandering wind turbine wakes, which together...... dictates the fatigue loading of the individual wind turbines. Within an optimization context, the basic challenge in describing the in-stationary wind farm flow field is computational speed. The Dynamic Wake Meandering (DWM) model includes the basic features of a CFD Large Eddy Simulation approach...

  18. Fabrication of Barrier Ribs for PDP by Capillary Infiltration Process and Their Sintering Behavior

    Institute of Scientific and Technical Information of China (English)

    Tae Jung Tang; Hak Nynu Choi; Chan Hyoung Kang; Yong Seog Kim

    2004-01-01

    Closed-cell type barrier ribs such as meander, honeycomb, SDR, and waffle types were produced using capillary molding process. Sintering of the ribs revealed that the ribs with asymmetric geometry such as meander and SDR type became distorted severely by the sintering process, but the ribs with symmetric geometry such as honeycomb and waffle type maintained their green state morphology. After sintering, the ribs were coated with green phosphor using osmosis coating process and its luminance characteristics were evaluated. The results indicated that the luminance and its efficiency is improved by using closed-cell type ribs with the new phosphor forming technology.

  19. Marine magnetic anomalies as a link between the granulite belts of east coast of India and enderby land of Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Murthy, K.S.R.; Rao, M.M.M.; Venkateswarlu, K.; Subrahmanyam, A.S.; Lakshminarayana, S.; Rao, T.C.S.

    Magnetic data of the eastern continental margin of India (ECMI) helped in demarcating the offshore extension of the granulite belts of east coast of India and their possible link to those of the East Aantarctica. Short wavelength and high amplitude...

  20. Ultrasound-induced encapsulated microbubble phenomena

    NARCIS (Netherlands)

    Postema, Michiel; Wamel, van Annemieke; Lancée, Charles T.; Jong, de Nico

    2004-01-01

    When encapsulated microbubbles are subjected to high-amplitude ultrasound, the following phenomena have been reported: oscillation, translation, coalescence, fragmentation, sonic cracking and jetting. In this paper, we explain these phenomena, based on theories that were validated for relatively big

  1. Delineation of structural lineaments from marine magnetic anomalies off Lawson's Bay (Visakhapatnam), East Coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Murthy, K.S.R.; Rao, T.C.S.; Rao, M.M.M.

    Marine magnetic surveys have recorded total field anomalies that correspond to structural lineaments extending from the coast into the sea. The significant anomalies recorded in this area are along wavelength high amplitude negative anomaly...

  2. Measurement and Mapping of Riverine Environments by Optical Remote Sensing

    Science.gov (United States)

    2011-09-30

    we also 4 conduted a high-resolution, intensive survey of a meander bend that we have monitired each year since 2005 and is now in the midst of a...optical and thermal remote sensing as part of their Riverine Dynamics Experiment 4. Beginning tomorrow (9-30-2011), we will be working with Arete at

  3. Instructor Gallery. Homage to the Laborer.

    Science.gov (United States)

    Vanelli, Jill

    1991-01-01

    Discusses the life and paintings of Vincent van Gogh, focusing on "The Road Meanders," and describes how to teach students through the painting (e.g., analyzing colors, discussing feelings it evokes, and writing poems that speak to the people in the painting). A copy of the painting is included. (SM)

  4. Powerful polymeric thermal microactuator with embedded silicon microstructure

    NARCIS (Netherlands)

    Lau, G.K.; Goosen, J.F.L.; Van Keulen, F.; Chu Duc, T.; Sarro, P.M.

    2007-01-01

    A powerful and effective design of a polymeric thermal microactuator is presented. The design has SU-8 epoxy layers filled and bonded in a meandering silicon (Si) microstructure. The silicon microstructure reinforces the SU-8 layers by lateral restraint. It also improves the transverse thermal expan

  5. Elevation Contours of the Bathymetry near Shorty's Island and Myrtle Bend, Koootenai River near Bonners Ferry, ID, 2010

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The elevation contour data was created based on bathymetry obtained in the meander reach collected in about a one month period extending from 6/3/2010 - 6/19/2010....

  6. Distichopora vervoorti, a new shallow-water stylasterid coral (Cnidaria: Hydrozoa: Stylasteridae) from Bali, Indonesia

    NARCIS (Netherlands)

    Cairns, S.D.; Hoeksema, B.W.

    1998-01-01

    A new species of stylasterid coral, Distichopora vervoorti, is described from shallow water off Bali, Indonesia. Although similar to D. irregularis in having meandering pore rows, it differs from that species in colony and branch shape, coenosteal colour, and expression of the ampullae.

  7. Graphene based piezoresistive pressure sensor

    NARCIS (Netherlands)

    Zhu, S.E.; Ghatkesar, M.K.; Zhang, C.; Janssen, G.C.A.M.

    2013-01-01

    We present a pressure sensor based on the piezoresistive effect of graphene. The sensor is a 100 nm thick, 280 μm wide square silicon nitride membrane with graphene meander patterns located on the maximum strain area. The multilayer, polycrystalline graphene was obtained by chemical vapor

  8. A dynamical systems approach to actin-based motility in Listeria monocytogenes

    Science.gov (United States)

    Hotton, S.

    2010-11-01

    A simple kinematic model for the trajectories of Listeria monocytogenes is generalized to a dynamical system rich enough to exhibit the resonant Hopf bifurcation structure of excitable media and simple enough to be studied geometrically. It is shown how L. monocytogenes trajectories and meandering spiral waves are organized by the same type of attracting set.

  9. Submesoscale cyclones in the Agulhas Current

    CSIR Research Space (South Africa)

    Krug, Marjolaine

    2017-01-01

    Full Text Available a period of 1 month provide the first high resolution observations of the Agulhas Current’s inshore front. The observations collected in a non-meandering Agulhas Current show the presence of submesoscale cyclonic eddies, generated at the inshore...

  10. Graphene based piezoresistive pressure sensor

    NARCIS (Netherlands)

    Zhu, S.E.; Ghatkesar, M.K.; Zhang, C.; Janssen, G.C.A.M.

    2013-01-01

    We present a pressure sensor based on the piezoresistive effect of graphene. The sensor is a 100 nm thick, 280 μm wide square silicon nitride membrane with graphene meander patterns located on the maximum strain area. The multilayer, polycrystalline graphene was obtained by chemical vapor deposition

  11. 27 CFR 9.53 - Alexander Valley.

    Science.gov (United States)

    2010-04-01

    ... on the northeasterly line of “Olive Hill” Cemetery, lying on the easterly side of a light-duty road... most easterly point thereon; (17) Then southerly 3,000 feet along the meanders of the west fork of Wood... identified as Lytton Springs Road in T. 9 N., R. 9 W.; (21) Then easterly along Lytton Springs Road to...

  12. Improved numerical modelling of morphodynamics of rivers with steep banks

    Science.gov (United States)

    The flow and sediment transport processes near steep streambanks, which are commonly found in meandering, braided, and anastomosing stream systems, exhibit complex patterns. The interactions between bed and bank morphologic adjustment, and their governing processes are still not well understood. Inc...

  13. The electrocurrent microrelay modelling

    Directory of Open Access Journals (Sweden)

    Mukhurov N. I.

    2011-06-01

    Full Text Available The design and method of electrocurrent microrelay theoretical modelling is offered. It is established, that base function in the normalized kind graphically represents a symmetric parabola. Microrelay capability evaluation have been carried out for different current flow directions through the meander-line system of planar structure.

  14. Multiple focused EMAT designs for improved surface breaking defect characterization

    Science.gov (United States)

    Thring, C. B.; Fan, Y.; Edwards, R. S.

    2017-02-01

    Ultrasonic Rayleigh waves can be employed for the detection of surface breaking defects such as rolling contact fatigue and stress corrosion cracking. Electromagnetic Acoustic Transducers (EMATs) are well suited to this technique as they can directly generate Rayleigh waves within the sample without the requirement for wedges, and they are robust and inexpensive compared to laser ultrasonics. Three different EMAT coil types have been developed, and these are compared to assess their ability to detect and characterize small (down to 0.5 mm depth, 1 mm diameter) surface breaking defects in aluminium. These designs are: a pair of linear meander coils used in a pseudo-pulse-echo mode, a pair of focused meander coils also used in pseudo-pulse-echo mode, and a pair of focused racetrack coils used in pitch-catch mode. The linear meander coils are able to detect most of the defects tested, but have a much lower signal to noise ratio and give limited sizing information. The focused meander coils and the focused racetrack coils can detect all defects tested, but have the advantage that they can also characterize the defect sizes on the sample surface, and have a stronger sensitivity at their focal point. Measurements using all three EMAT designs are presented and compared for high resolution imaging of surface-breaking defects.

  15. Graphene based piezoresistive pressure sensor

    NARCIS (Netherlands)

    Zhu, S.E.; Ghatkesar, M.K.; Zhang, C.; Janssen, G.C.A.M.

    2013-01-01

    We present a pressure sensor based on the piezoresistive effect of graphene. The sensor is a 100 nm thick, 280 μm wide square silicon nitride membrane with graphene meander patterns located on the maximum strain area. The multilayer, polycrystalline graphene was obtained by chemical vapor deposition

  16. არაფერი | araperi (Nothing)

    DEFF Research Database (Denmark)

    2014-01-01

    reflecting - as in white - or none at all, all absorbing - as in black - the impact on the visual perception is of "nothing" in itself, but, put in relation with everything, "k'velaperi", - literally "all color(s)" -, it meanders, borrowing from Alenka Zupancic, "...to nothingness as minimal difference...

  17. Een vegetatiewaardering van het stroomdallandschap van het Merkske (N.-Br.), gebaseerd op een floristische inventarisatie

    NARCIS (Netherlands)

    Mennema, J.

    1973-01-01

    The vegetation of the valley of the rivulet Merkske; an evaluation based on a floristic investigation The valley of the meandering rivulet Merkske (in the province of Noord-Brabant, Netherlands, and the province of Antwerp, Belgium) is menaced with deterioration by the intended canalization of the m

  18. StemBells: A novel stem cell delivery platform using microbubbles and ultrasound

    NARCIS (Netherlands)

    T.J.A. Kokhuis (Tom)

    2014-01-01

    markdownabstract__Abstract__ Bubbles are omnipresent. It is the popping of bubbles present in the water that produces the characteristic sound of meandering brooks, boiling water [1] and breaking waves at the beach. The popping of bubbles can generate great forces, an effect which is employed in ul

  19. Wave-current interaction near the Gulf Stream during the surface wave dynamics experiment

    Science.gov (United States)

    Wang, David W.; Liu, Antony K.; Peng, Chih Y.; Meindl, Eric A.

    1994-01-01

    This paper presents a case study on the wave-current interaction near the local curvature of a Gulf Stream meander. The wave data were obtained from in situ measurements by a pitch-roll discus buoy during the Surface Wave Dynamics Experiment (SWADE) conducted off Wallops Island, Virginia, from October 1990 to March 1991. Owing to the advection of the Gulf Stream by the semidiurnal tide, the discus buoy was alternately located outside and inside the Gulf Stream. The directional wave measurements from the buoy show the changes in wave direction, wave energy, and directional spreading when waves encountered the current in the Gulf Stream meanders. A wave refraction model, using the ray-tracing method with an estimated Gulf Stream velocity field and meandering condition, was used to simulate wave refraction patterns and to estimate wave parameters at relative locations corresponding to buoy measurements. The numerical simulation shows that a focusing zone of wave rays was formed near the boundary and behind the crest of a simulated Gulf Stream meander. The focusing of wave rays causes changes in wave direction, increases in wave energy, and decreases in wave directional spreading, which are in good agreement with the results from the buoy measurements.

  20. Gulf Stream Ring Coalescence with the Gulf Stream off Cape Hatteras.

    Science.gov (United States)

    Watts, D R; Olson, D B

    1978-12-01

    A cyclonic ring, which had separated from the Gulf Stream 7 months earlier and traveled 500 kilometers westward, collided with the stream in September 1977. Within 3 days the ring and stream joined to form a sharp S-shaped meander. Shipboard expendable temperature probes and four bottom-moored inverted echo sounders were used to obtain synoptic descriptions of the rejoining process.

  1. StemBells: A novel stem cell delivery platform using microbubbles and ultrasound

    NARCIS (Netherlands)

    T.J.A. Kokhuis (Tom)

    2014-01-01

    markdownabstract__Abstract__ Bubbles are omnipresent. It is the popping of bubbles present in the water that produces the characteristic sound of meandering brooks, boiling water [1] and breaking waves at the beach. The popping of bubbles can generate great forces, an effect which is employed in ul

  2. 10 käsku elu püsimiseks / Arni Alandi

    Index Scriptorium Estoniae

    Alandi, Arni, 1969-

    2006-01-01

    Taanis elav USA ökoloog, keskkonnauudiseid koguva ja vahendava võrgukeskkonna Ecological Internet asutaja ning blogi Earth Meanders autor, dr Glen Barry pakub välja kümme eeldust inimkonna püsimajäämiseks

  3. The River Gelså restoration revisited: Habitat specific assemblages and persistence of the macroinvertebrate community over an 11-year period

    DEFF Research Database (Denmark)

    Friberg, Nikolai; Baattrup-Pedersen, Annette; Kristensen, Esben Astrup;

    2014-01-01

    The study was undertaken on the River Gelså, Denmark, where a 1.8 km meandering course was estab-lished in 1989 to replace a channelized river reach. This restoration project was the first of its kind inDenmark and has the longest time-series of post-intervention data of any restoration project c...

  4. Thirsty Cities,Dirty Water

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Rapid economic growth has taken a toll on water quality Houses lining up meandering rivers make Jiaxing in east China’s Zhejiang Province a famed water city.Yet the Venetian-style center is suffering from a water shortage.Jiaxing has a population of more than 3

  5. 77 FR 26569 - Llano Seco Riparian Sanctuary Unit Restoration and Pumping Plant/Fish Screen Facility Protection...

    Science.gov (United States)

    2012-05-04

    ... to prevent river meander. Alternative 2: Spur Dikes and Site-Specific Plantings Under Alternative 2, bank protection measures would consist of installing eight rock spur dikes along the Sacramento River on the northern side of the Riparian Sanctuary. The dike field would extend about 2,000 feet...

  6. Dynamics of the Spiral Tip in a Closed Belousov-Zhabotinsky Reaction

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui-Jie; WANG Peng-Ye; ZHAO Ying-Ying

    2005-01-01

    @@ Dynamics of spiral tip rotating in a closed system of the light sensitive Belousov-Zhabotinsky reaction is studied under a homogeneous and steady illumination. The time dependence of the kinematical parameters of meandering spiral is presented and the experimental evidence is obtained for self-synchronization of the spiral tip in a closed B-Z system without external feedback.

  7. A new approach to river bank retreat and advance in 2D numerical models of fluvial morphodynamics

    NARCIS (Netherlands)

    Spruyt, A.; Mosselman, E.; Jagers, B.

    2011-01-01

    River bank retreat and advance are modes of morphological evolution in addition to bed level changes and changes in bed sediment composition. They produce planform changes such as width adjustment and meander bend migration. However, their reproduction in a 2D numerical model still remains a challen

  8. Morphological assessment of reconstructed lowland streams in the Netherlands

    NARCIS (Netherlands)

    Eekhout, J.P.C.; Hoitink, Ton; Brouwer, de J.H.F.; Verdonschot, P.F.M.

    2015-01-01

    Channelisation measures taken halfway the 20th century have had destructive consequences for the diversity of the ecology in the majority of the lowland streams in countries such as the Netherlands. Re-meandering is the common practice in restoring these lowland streams. Three reconstructed

  9. De TNO OK simulator

    NARCIS (Netherlands)

    Litsenburg, C. van

    2015-01-01

    Onlangs werd de OK-simulator van TNO officieel in gebruik genomen. Prof. Dr. Ivo Broeders, hoogleraar Robotica en minimaal invasie technieken aan de Universiteit Twente en chirurg in het Meander Medisch Centrum was één van de inleiders tijdens de presentatie

  10. Vegetation and Channel Morphology Responses to Ordinary High Water Discharge Events in Arid West Stream Channels

    Science.gov (United States)

    2009-05-01

    from aggrading main channel Single-thread channels with adjacent floodplains – Meandering that develops to minimize amount of change at...widening with bank destabilization – Aggradation due to decrease in capacity to transport sediment ERDC/CRREL TR-09-5 6 3 Methods In an

  11. A Computational Model to Simulate Groundwater Seepage Risk in Support of Geotechnical Investigations of Levee and Dam Projects

    Science.gov (United States)

    2013-03-01

    process-imitating rules. The model aggrades an alluvial floodplain, creating floodplain architecture by differentiating between sediment deposited by...meandering rivers. The results suggest that the channel aggradation rate influenced heavily the relative channel avulsion frequency during floodplain...composition and organization of the river basin and its floodplain (Schumm 1968). In an actively building ( aggrading ) floodplain, the river channel is

  12. Soil and water characteristics in restored canebrake and forest riparian zones

    Science.gov (United States)

    Danielle M. Andrews; Christopher D. Barton; Randy Kolka; Charles C. Rhoades; Adam J. Dattilo

    2011-01-01

    The degradation of streams has been widespread in the United States. In Kentucky, for instance, almost all of its large streams have been impounded or channelized. A restoration project was initiated in a channelized section of Wilson Creek (Nelson Co., Kentucky) to return its predisturbance meandering configuration. A goal of the project was to restore the native...

  13. Bimodal behavior of the Kuroshio and the Gulf Stream

    NARCIS (Netherlands)

    Schmeits, M.J.; Dijkstra, H.A.

    2001-01-01

    For a long time, observations have been pointing out that the Kuroshio in the North Paciffc Ocean displays bimodal meandering behavior of the southern coast of Japan. For the Gulf Stream in the North Atlantic Ocean, weakly and strongly deffected paths near the coast of South Carolina have been obser

  14. A Study of Vegetation on Revetments Sacramento River Bank Protection Project. Phase 1. Literature Review and Pilot Study

    Science.gov (United States)

    1990-11-01

    clays that were resistant to erosion and locally affected bank erosion patterns. Ancient meander belt deposits such as the Modesto Formation also had a...and Wildlife Service, Portland, OR. Gilbert, G. K. 1917. "Hydraulic Mining Debris in the Sierra Nevada," Geological Survey Professional Paper 105, US

  15. Bathymetric surveys of the Kootenai River near Bonners Ferry, Idaho, water year 2011

    Science.gov (United States)

    Fosness, Ryan L.

    2013-01-01

    In 2009, the Kootenai Tribe of Idaho released and implemented the Kootenai River Habitat Restoration Master Plan. This plan aimed to restore, enhance, and maintain the Kootenai River habitat and landscape to support and sustain habitat conditions for aquatic species and animal populations. In support of these restoration efforts, the U.S. Geological Survey, in cooperation with the Kootenai Tribe of Idaho, conducted high-resolution multibeam echosounder bathymetric surveys in May, June, and July 2011, as a baseline bathymetric monitoring survey on the Kootenai River near Bonners Ferry, Idaho. Three channel patterns or reaches exist in the study area—braided, meander, and a transitional zone connecting the braided and meander reaches. Bathymetric data were collected at three study areas in 2011 to provide: (1) surveys in unmapped portions of the meander reach; (2) monitoring of the presence and extent of sand along planned lines within a section of the meander reach; and (3) monitoring aggradation and degradation of the channel bed at specific cross sections within the braided reach and transitional zone. The bathymetric data will be used to update and verify flow models, calibrate and verify sediment transport modeling efforts, and aid in the biological assessment in support of the Kootenai River Habitat Restoration Master Plan. The data and planned lines for each study reach were produced in ASCII XYZ format supported by most geospatial software.

  16. Large-eddy simulation of a curved open-channel flow over topography

    NARCIS (Netherlands)

    Van Balen, W.; Uijttewaal, W.S.J.; Blanckaert, K.

    2010-01-01

    Large-eddy simulation (LES) is performed of a curved open-channel flow over topography based on the laboratory experiment by Blanckaert [“Topographic steering, flow circulation, velocity redistribution and bed topography in sharp meander bends,” Water Resour. Res., doi:10.1029/2009WR008303 (in press

  17. Detection and monitoring of invasive exotic plants: a comparison of four sampling methods

    Science.gov (United States)

    Cynthia D. Huebner

    2007-01-01

    The ability to detect and monitor exotic invasive plants is likely to vary depending on the sampling method employed. Methods with strong qualitative thoroughness for species detection often lack the intensity necessary to monitor vegetation change. Four sampling methods (systematic plot, stratified-random plot, modified Whittaker, and timed meander) in hemlock and red...

  18. Impacts of non-native plant removal on vertebrates along the Middle Rio Grande (New Mexico)

    Science.gov (United States)

    Heather L. Bateman; Alice Chung-MacCoubrey; Deborah M. Finch; Howard L. Snell; David L. Hawksworth

    2008-01-01

    The Middle Rio Grande and its riparian forest in central New Mexico are the focus of restoration activities to reverse or lessen negative anthropogenic impacts. The riparian forest is the largest gallery cottonwood (Populus deltoides) forest in the Southwest (Hink and Ohmart 1984). Historically, the river was free to meander across the floodplain,...

  19. Large-eddy simulation of a curved open-channel flow over topography

    NARCIS (Netherlands)

    Van Balen, W.; Uijttewaal, W.S.J.; Blanckaert, K.

    2010-01-01

    Large-eddy simulation (LES) is performed of a curved open-channel flow over topography based on the laboratory experiment by Blanckaert [“Topographic steering, flow circulation, velocity redistribution and bed topography in sharp meander bends,” Water Resour. Res., doi:10.1029/2009WR008303 (in press

  20. Micro-stereolithography as a transducer design method.

    Science.gov (United States)

    Ho, K S; Bradley, R J; Billson, D R; Hutchins, D A

    2008-03-01

    This paper investigates the use of micro-stereolithography, a rapid prototyping technique, in the manufacture of transducers. It is illustrated for the production of electromagnetic acoustic transducer (EMATs) coils in both meander-line and spiral configurations. A synthetic aperture focussing technique (SAFT) has been applied to the ultrasonic signals from these devices to reconstruct images in metallic objects.

  1. De TNO OK simulator

    NARCIS (Netherlands)

    Litsenburg, C. van

    2015-01-01

    Onlangs werd de OK-simulator van TNO officieel in gebruik genomen. Prof. Dr. Ivo Broeders, hoogleraar Robotica en minimaal invasie technieken aan de Universiteit Twente en chirurg in het Meander Medisch Centrum was één van de inleiders tijdens de presentatie

  2. On the Simulation of Floods in a Narrow Bending Valley: The Malpasset Dam Break Case Study

    Directory of Open Access Journals (Sweden)

    Chiara Biscarini

    2016-11-01

    Full Text Available In this paper, we investigate the performance of three-dimensional (3D hydraulic modeling when dealing with river sinuosity and meander bends. In river bends, the flow is dominated by a secondary current, which has a key role on the flow redistribution. The secondary flow induces transverse components of the bed shear stress and increases the velocity in outward direction, thus generating local erosion and riverbed modifications. When in river bends, the 3D processes prevail, and a 3D computational fluid dynamics (CFD model is required to correctly predict the flow structure. An accurate description of the different hydrodynamic processes in mildly and sharply curved bends find a relevant application in meanders migration modeling. The mechanisms that drive the velocity redistribution in meandering channels depend on the river’s roughness, the flow depth (H, the radius curvature (R, the width (B and the bathymetric variations. Here, the hydro-geomorphic characterization of sharp and mild meanders is performed by means of the ratios R/B, B/H, and R/H, and of the sinuosity index. As a case study, we selected the Malpasset dam break on the Reyran River Valley (FR, as it is perfectly suited for investigating performances and issues of a 3D model in simulating the inundation dynamics in a river channel with a varying curvature radius.

  3. Chute cutoff as a morphological response to stream reconstruction

    NARCIS (Netherlands)

    Eekhout, J.P.C.; Hoitink, A.J.F.

    2015-01-01

    Stream restoration efforts often aim at creating new unconstrained meandering channels without weirs and bank revetments. In reconstructed streams, the initial morphological response of the new streams is often rapid, until a dynamic equilibrium is reached. Here we report on a chute cutoff that o

  4. Fiber-coupled NbN superconducting single-photon detectors for quantum correlation measurements

    NARCIS (Netherlands)

    Slysz, W.; Wegrzecki, M.; Bar, J.; Grabiec, P.; Gorska, M.; Reiger, E.; Dorenbos, S.; Zwiller, V.; Milostnaya, I.; Minaeva, O.

    2007-01-01

    We have fabricated fiber-coupled superconducting single-photon detectors (SSPDs), designed for quantum-correlationtype experiments. The SSPDs are nanostructured (~100-nm wide and 4-nm thick) NbN superconducting meandering stripes, operated in the 2 to 4.2 K temperature range, and known for ultrafast

  5. Gulf of Mexico Loop Current path variability

    Science.gov (United States)

    Donohue, K. A.; Watts, D. R.; Hamilton, P.; Leben, R.; Kennelly, M.; Lugo-Fernández, A.

    2016-12-01

    Loop Current, LC, path variability exhibits a continuum of spatial and temporal scales, all are called meanders in this work. They arise from a variety of processes, including short and long waves, frontal eddies with or without closed cores and developing baroclinic instability. They have been extensively studied with satellite sea surface temperature SST, and height, SSH. Yet, these systems provide an incomplete view into LC meandering: SST measurements are hampered by cloud coverage and low thermal contrast in summer months and SSH measurements by altimeter temporal and spatial resolution. In an effort to resolve LC meander temporal and spatial scales, they are investigated using a mesoscale resolving in situ array deployed in the Gulf of Mexico. The array, which consisted of twenty-five inverted echo sounders with pressure gauges, PIES, and current meter moorings, was deployed April 2009 and recovered in October-November 2011. The broad extent of the array, nominally 89° W to 85° W, 25° N to 27° N, enabled quantitative mapping of the regional circulation. LC meander properties are characterized as a function of spatial distribution of energy, frequency, wavenumber, and phase speed. Dispersion characteristics and meander scales are comparable to those found in the Gulf Stream. Phase speeds increase with frequency and range from 8 to 50 km d-1. Wavelengths associated with each band are as follows: 460 km for the 100 to 40 d band, 350 km for the 40 to 20 d band, 270 km for the 20 to 10 d band and 230 km for the 10 to 3 d band. The strongest variability is in the 100 to 40 d band. Spatially the 100 to 40 d variability is concentrated to east of the Mississippi Fan, growing and propagating downstream along the eastern portion of the LC. Meanders between 40 and 20 d propagate along the full encompassed length of the LC. Their temporal amplitudes peak at the time of LC eddy detachment and separation. Meanders with shorter periods than 20 d do not always propagate

  6. The eddy-dipole mode interaction and the decadal variability of the Kuroshio Extension system

    Science.gov (United States)

    Luo, Dehai; Feng, Shaohua; Wu, Lixin

    2016-10-01

    In this paper, the physical cause of why the eddy kinetic energy (EKE) in the upstream Kuroshio Extension (KE) region is strong (weak) during a large (small) jet meandering period is studied by using the satellite altimeter data and constructing an eddy-dipole mode interaction theory from a reduced gravity shallow water wave quasi-geostrophic vorticity equation. It is found that the large KE jet meander corresponds to a large-scale positive-over-negative dipole SSH anomaly (KED- mode, hereafter), a double-branch jet with a weak strength and a strong EKE in the upstream KE region, while the small jet meander corresponds to a negative-over-positive dipole anomaly (KED+ mode, hereafter), a strong single-branch jet, and a weak EKE. Further diagnostics using this new eddy-dipole mode interaction theory reveals that the horizontal advection and KED deformation field can change the eddy activity in the upstream KE region. When the KED- mode is amplified by mesoscale eddies, the EKE grows by extracting energy from the KED- deformation (shearing and stretching) field and due to a reduced eastward advection, thus showing a high EKE level during the KED- mode (large jet meander) episode. In contrast, when the KED+ mode is intensified, the kinetic energy of the eddy weakens by losing its energy to the KED+ deformation field and by an enhanced eastward advection, thus showing a low EKE level during the KED+ mode (small jet meander) episode. Because the KED mode shows a clear decadal variation due to the modulation of the Pacific Decadal Oscillation, both the KE jet and EKE exhibit inevitably a distinct decadal variability.

  7. Investigation of the Spatial Patterns of Velocity and Bed Morphology Within Actively Evolving Neck Cutoffs on a Highly Sinuous River

    Science.gov (United States)

    Richards, D.; Konsoer, K. M.; Turnipseed, C.; Willson, C. S.

    2016-12-01

    Meander bend cutoffs and oxbow lakes are essential and ubiquitous features of meandering river floodplains. Yet, the processes involved in the evolution of an elongated bend to neck cutoff and oxbow lake are incompletely understood. Five neck cutoffs occurring on the White River, Arkansas, with two types of planform geometries, and one elongate meander loop prior to cutoff were examined for this study. Three-dimensional velocities were obtained using an acoustic Doppler current profiler (ADCP), and high-resolution channel bathymetry was collected using multi-beam echo sounder (MBES). Results show similar patterns of acceleration of velocity with nearly 180 degree redirection of the flow through the cutoff, strong advection of high momentum toward the far bank, and multiple zones of flow separation and recirculation. This pattern of velocity leads to increased bank erosion rates on the downstream bank opposite of the cutoff, bar formation downstream of the cutoff along the adjacent banks, and relatively deep scour pools located within the region of flow acceleration immediately downstream of the cutoff. Analysis of high-resolution channel bathymetry show a wide range in bedform morphology, the presence of amalgamating unit bars, and a lack of sediment accumulation within the entrance and exit to the abandoned meander loops. The findings from this investigation reveal that the evolution of these neck cutoffs do not conform to current conceptual models of meander cutoff and oxbow lake formation, suggesting that cutoff location, planform geometry, and length of channel removed are important factors in determining planform evolution and the hydrologic connectivity of the abandoned bend to the active channel.

  8. Gis Based Multi-Risk and Vulnerability Assessment. A Case Study for Niraj basin area (Transylvanian Depression, Romania)

    Science.gov (United States)

    Rosca, Sanda; Petrea, Danut; Bilasco, Stefan; Vescan, Iuliu; Fodorean, Ioan

    2015-04-01

    Natural hazards such as landslides, meandering and flash floods have caused economical damage and environmental changes in the last period of time increasing the risk level of the built-up areas and roads from Romania. Thus, an essential role in the prevention of negative effects and the identification of natural risks is played by the generation of hazard and risk maps. The purpose of the study is represented by the generation of multi-hazard and multi-risk maps using GIS technologies, which requires the identification of cumulated risk for each administrative-territorial unit situated in the study area of Niraj river basin from Transylvania Depression, Romania. The first stage in this approach was to develop the flood risk zonation which is based on floodable stripes, obtained using statistical analysis of past data series and their integration in determinist spatial analysis models, generated as a product of temporal flood probability and vulnerability of the territory. The probability of landslide occurrence was estimated using bivariate statistical analysis, by evaluating the importance of each class of preparatory factors depending of the characteristic/local conditions: lithology, geomorphology, structure, hydro-climatic factors, hydrogeology, seismicity, forestry and anthropogenic factor. Finally, the assessment of the risk associated to lateral river erosion, or meandering, was obtained by using the largest time span available (of the last 102 years) in order to identify the river's present dynamic trends of each river meander. The average and the maximum rate of erosion values were used to determine the meandering potential and to identify the meandering risk zones. Therefore, in order to accurately identify the local risk level, we calculated the spatial and temporal probability of occurrence of potential damaging events, as well as the distribution of the elements at risk based on their characteristic vulnerability. The final results represent valuable

  9. Vegetative impacts upon bedload transport capacity and channel stability for differing alluvial planforms in the Yellow River source zone

    Science.gov (United States)

    Li, Zhi Wei; Yu, Guo An; Brierley, Gary; Wang, Zhao Yin

    2016-07-01

    The influence of vegetation upon bedload transport and channel morphodynamics is examined along a channel stability gradient ranging from meandering to anabranching to anabranching-braided to fully braided planform conditions along trunk and tributary reaches of the Upper Yellow River in western China. Although the regional geology and climate are relatively consistent across the study area, there is a distinct gradient in the presence and abundance of riparian vegetation for these reaches atop the Qinghai-Tibet Plateau (elevations in the study area range from 2800 to 3400 m a.s.l.). To date, the influence of vegetative impacts upon channel planform and bedload transport capacity of alluvial reaches of the Upper Yellow River remains unclear because of a lack of hydrological and field data. In this region, the types and pattern of riparian vegetation vary with planform type as follows: trees exert the strongest influence in the anabranching reach, the meandering reach flows through meadow vegetation, the anabranching-braided reach has a grass, herb, and sparse shrub cover, and the braided reach has no riparian vegetation. A non-linear relation between vegetative cover on the valley floor and bedload transport capacity is evident, wherein bedload transport capacity is the highest for the anabranching reach, roughly followed by the anabranching-braided, braided, and meandering reaches. The relationship between the bedload transport capacity of a reach and sediment supply from upstream exerts a significant influence upon channel stability. Bedload transport capacity during the flood season (June-September) in the braided reach is much less than the rate of sediment supply, inducing bed aggradation and dynamic channel adjustments. Rates of channel adjustment are less pronounced for the anabranching-braided and anabranching reaches, while the meandering reach is relatively stable (i.e., this is a passive meandering reach).

  10. Committees

    Science.gov (United States)

    2003-08-01

    Born in Buenos Aires, Argentina, in 1930, Alberto Sirlin studied at the University of Buenos Aires from 1948-52, where he carried out research work in classical nonlinear physics, under the guidance of Richard Gans, and in 1953 received the degree of doctor in Physical-Mathematical Sciences. In 1953 he held a fellowship at the Centro Brasileiro de Pesquisas Fisicas in Rio de Janeiro, Brazil, where he did research work and attended some graduate courses, including a memorable and highly influential one taught by Richard Feynman. He spent the academic year 1954-55 at UCLA, where he initiated his work on electroweak physics in collaboration with Robert Finkelstein and Ralph Behrends. His next move was to Cornell University in 1955, earning his PhD there in 1958 for research in electroweak physics in collaboration with Toichiro Kinoshita. Sirlin spent 1957-59 as a research associate at Columbia University, becoming an Assistant Professor of Physics at New York University in 1959, an Associate Professor in 1961, and a full Professor in 1968. It is a remarkable coincidence that one of his fellow post-docs, Steven Weinberg, was to become one of the founders of the Standard Model, which in turn has provided the natural setting for Sirlin's work. During his formative years, he was extremely fortunate to receive guidance and advice from an extraordinary group of distinguished scientists, including R Gans, R P Feynman, R J Finkelstein, H A Bethe and E E Salpeter. He also enjoyed close and fruitful long-term collaborations with a number of brilliant theorists, including R E Behrends, T Kinoshita, T D Lee, M A B Beg, W J Marciano, P Langacker, G Degrassi, P Gambino and B A Kniehl, and has had fourteen excellent, interesting, and highly enterprising graduate students, who have remained close friends. Sirlin's main research interests have been in precision electroweak physics, other topics in weak interaction theory, the search for higher symmetries of the strong interactions

  11. The First D/V Chikyu IODP Operations: Successful Logging and Coring During NanTroSEIZE Stage 1 Expeditions

    Directory of Open Access Journals (Sweden)

    Moe Kyaw Thu

    2008-07-01

    Full Text Available The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE is a multi-expedition IODP drilling project aimed at drilling, coring, logging, and instrumenting the seismogenic zone of an active subduction margin , in a region thought to generate megathrust earthquakes of magnitude >8.0 on the moment-magnitude scale (Tobin and Kinoshita, 2006. The Nankai Trough, offshore of the Kii Peninsula, Honshu, Japan (Fig. 1 was chosen as the location for thisproject based on a number of scientific drilling proposals to IODP. These reviewed existing drilling data in the region, the long-term historical and recent record of great earthquakes, the social and societal relevance of the area, and the accessibility of the seismogenic zone to present drilling technology. The first stage of this multi-stage project was intended to accomplish a broad characterization of the shallow geology, geophysics, physical properties, heat flow, and fluid flow in a transect across the downgoing Philippine Sea Plate, the toe of the Nankai accretionary prism, the megasplay fault zone region on the continental slope, and the Kumano Basin that lies between the accretionary prism and the KiiPeninsula, on the continental shelf (Fig. 2.

  12. New Records of Cold-Water Corals from Korea

    Directory of Open Access Journals (Sweden)

    Jun-Im Song

    2016-07-01

    Full Text Available Two cold-water coral taxa, Octocorallia in the class Anthozoa and Stylasteridae in the class Hydrozoa, were identified. Deep-water samples were collected in fishing nets at depths ranging between 20 and 200 m along the coasts of the East Sea in Korea from 1976 to 1993. The two species found in this study represent new records for Korea: Paragorgia arborea (Linnaeus, 1758 in the class Anthozoa, and Stylaster profundiporus Broch, 1936 in the class Hydrozoa. Two families, Paragorgiidae and Stylasteridae, are also newly recorded in Korea. Furthermore, the species name of another cold-water gorgonian species, Primnoa pacifica (Kinoshita, 1907 in the family Primnoidae, is amended in this report. The two newly recorded cold-water coral species from Korea are described in detail based on their morphological characteristics. Paragorgia arborea is characterized by its growth form, medulla and cortex, zooid dimorphism, canal system, and spicule composition. Stylaster profundiporus is distinguished by its external skeletal characteristics, such as the coordination of dactylopores and gastropores, presence or absence of gastrostyles and dactylostyles, cyclosystem orientation, ampullar position, gastropore tube shape, and coenosteal texture.

  13. Array measurements of long-period microtremors in southwestern Kanto plain, Japan; Kanto heiya nanseibu ni okeru yaya choshuki bido no array kansoku

    Energy Technology Data Exchange (ETDEWEB)

    Yamanaka, H.; Sato, H.; Kurita, K.; Seo, K. [Tokyo Institute of Technology, Tokyo (Japan)

    1997-05-27

    Array measurements of long-period microtremors were carried out in the southwestern part of Kanto Plain, Japan, to obtain S-wave velocity structures in sedimentary beds as fundamental data for estimating long-term strong ground motion in Kanto Plain. The major component in a long-term seismic motion observed in Kanto Plain is the surface wave. According to the result of observations on Love wave by Kinoshita et al, the wavelengths of the surface waves of a long-term cycle are 10 to 20 km. Therefore, if an array observation is to be performed at intervals of about two wavelengths, about 40 points will be required to cover the entire Kanto plain. The final phase velocity is decided by averaging phase velocities of each cycle obtained for each data set. The acquired phase velocities are analyzed inversely by using a genetic algorithm to derive the S-wave velocities at each observation point. The present microtremor array observation has used 13 points in the southwestern part of Kanto Plain to acquire S-wave velocity (Vs) distribution in sedimentary beds. It was made clear that beds with Vs of 1.0 km/s and Vs of 1.5 km/s exist in this area between the surface bed and the seismic foundation with Vs of about 3 km/s. 10 refs., 10 figs., 1 tab.

  14. The rate of symptomatic improvement of congenital nasolacrimal duct obstruction in Japanese infants treated with conservative management during the 1st year of age

    Directory of Open Access Journals (Sweden)

    Hirohiko Kakizaki

    2008-06-01

    Full Text Available Hirohiko Kakizaki1, Yasuhiro Takahashi2, Shinsuke Kinoshita1, Kunihiko Shiraki2, Masayoshi Iwaki11Department of Ophthalmology, Aichi Medical University, Aichi, Japan; 2Department of Ophthalmology and Visual Sciences, Osaka City University Graduate School of Medicine, Osaka, JapanAbstract: This study aimed to examine the rate of symptomatic improvement of congenital nasolacrimal duct obstruction (CNLDO in Japanese infants treated with conservative management within the 1st year of age. Thirty-five lacrimal ducts in 27 patients diagnosed with CNLDO were included in the study. During the observational period, lacrimal ducts were massaged. As well, antibiotic eye drops, to be administered 4 times a day, were sometimes prescribed for obvious conjunctivitis. Two lacrimal ducts in 2 patients were probed before the 1st year of age because of dacryocystitis or severe blepharitis; these patients were included in the unimproved group. Twenty-nine lacrimal ducts in 21 patients resolved during the period (82.9%; with 16 lacrimal ducts resolving before six months of age. Therefore, a comparatively high percentage of resolution for CNLDO (82.9% following conservative management was shown before the 1st year of age in Japanese infants.Keywords: congenital nasolacrimal duct obstruction, symptomatic improvement, conservative management, massage, probing

  15. Facial nerve palsy: Evaluation by contrast-enhanced MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, T.; Ishii, K.; Okitsu, T.; Okudera, T.; Ogawa, T

    2001-11-01

    AIM: The purpose of this study was to investigate the value of contrast-enhanced magnetic resonance (MR) imaging in patients with peripheral facial nerve palsy. MATERIALS AND METHODS: MR imaging was performed in 147 patients with facial nerve palsy, using a 1.0 T unit. All of 147 patients were evaluated by contrast-enhanced MR imaging and the pattern of enhancement was compared with that in 300 control subjects evaluated for suspected acoustic neurinoma. RESULTS: The intrameatal and labyrinthine segments of the normal facial nerve did not show enhancement, whereas enhancement of the distal intrameatal segment and the labyrinthine segment was respectively found in 67% and 43% of patients with Bell's palsy. The geniculate ganglion or the tympanic-mastoid segment was enhanced in 21% of normal controls versus 91% of patients with Bell's palsy. Abnormal enhancement of the non-paralyzed facial nerve was found in a patient with bilateral temporal bone fracture. CONCLUSION: Enhancement of the distal intrameatal and labyrinthine segments is specific for facial nerve palsy. Contrast-enhanced MR imaging can reveal inflammatory facial nerve lesions and traumatic nerve injury, including clinically silent damage in trauma. Kinoshita T. et al. (2001)

  16. Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Wijewardhana, Rohana; Argyres, Philip

    2014-11-03

    Task A - Theory Research in theoretical physics in the Department of Physics at the University of Cincinnati has been funded by the U.S. Department of Energy starting in 1984. Professors Peter Suranyi, Louis Witten, Fred Mansouri, L.C.R. Wijewardhana, Alexander Kagan and Philip Argyres have served as P.I.'s of the Cincinnati DOE theory task. Task B - Heavy Flavor Physics Research in experimental particle physics in the Department of Physics at the University of Cincinnati has been funded by the U.S. Department of Energy since 1999. Professor Kay Kinoshita has served as P.I. on Task B since its inception. Task C - Neutrinos Over the past three years, Task C has been measuring the properties of neutrinos with the MiniBooNE and Daya Bay detectors and building two new neutrino experiments: MicroBooNE and LArIAT. In addition, the PI (Randy Johnson) has joined the long leadtime experiment, LBNE, and has participated in the R&D report for CHiPs. Results and progress on each of these experiments will be summarized below.

  17. Coronary arterial complications after percutaneous coronary intervention in Behçet’s disease

    Directory of Open Access Journals (Sweden)

    Kinoshita T

    2013-02-01

    Full Text Available Toshio Kinoshita,1 Shinichiro Fujimoto,1 Yukio Ishikawa,2 Hitomi Yuzawa,1 Shunji Fukunaga,1 Mikihito Toda,3 Kenji Wagatsuma,3 Yoshikiyo Akasaka,2 Toshiharu Ishii,2 Takanori Ikeda11Department of Cardiovascular Medicine, 2Department of Pathology, 3Division of Interventional Cardiology, Toho University Faculty of Medicine, Ohta City, Tokyo, JapanAbstract: Behçet’s disease is a multisystemic vascular inflammatory disease, but concurrent cardiac diseases, such as acute myocardial infarction, are rare. Several complications may arise after coronary intervention for coronary lesions that interfere with treatment, and the incidence of coronary arterial complications due to invasive therapy remains unclear. Further, the long-term outcomes in patients with Behçet’s disease after stenting for acute myocardial infarction have not been described. The present report describes a 35-year-old Japanese man with Behçet’s disease who developed acute myocardial infarction. A coronary aneurysm developed at the stenting site of the left anterior descending coronary artery, along with stenosis in the left anterior descending segment proximal to the site. Although invasive therapy was considered, medication including immunosuppressants was selected because of the high risk of vascular complications after invasive therapy. The coronary artery disease has remained asymptomatic for the 4 years since the patient started medication. This case underscores the importance of considering the incidence of coronary arterial complications and of conservative treatment when possible.Keywords: Behçet’s disease, myocardial infarction, coronary arterial complications, percutaneous coronary intervention, immunosuppressants

  18. Gravity field and solar component of the precession rate and nutation coefficients of Comet 67P Churyumov-Gerasimenko

    CERN Document Server

    Lhotka, Christoph; Souchay, Jean; Baur, Oliver

    2016-01-01

    The aim of this study is first to determine the gravity field of the comet 67P Churyumov-Gerasimenko and second to derive the solar component of the precession rate and nutation coefficients of the spin axis of the comet nucleus, i.e. without the direct, usually larger, effect of outgassing. The gravity field, and related moments of inertia, are obtained from two polyhedra, that are provided by the OSIRIS and NAV-CAM experiments on Rosetta, and are based on the assumption of uniform density for the comet nucleus. We also calculate the forced precession rate as well as the nutation coefficients on the basis of Kinoshita's theory of rotation of the rigid Earth and adapted it to be able to indirectly include the effect of outgassing on the rotational parameters. The 2nd degree denormalized Stokes coefficients of comet 67P C-G turn out to be (bracketed numbers refer to second shape model) C20 = -6.74 [-7.93] * 10^-2, C22 = 2.60 [2.71] * 10^-2 consistent with normalized principal moments of inertia A/MR^2 = 0.13 [...

  19. A simple stationary semi-analytical wake model

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.

    -uniform mean wind field, although the modelling of the individual stationary wake flow fields includes non-linear terms. The simulation of the individual wake contributions are based on an analytical solution of the thin shear layer approximation of the NS equations. The wake flow fields are assumed......We present an idealized simple, but fast, semi-analytical algorithm for computation of stationary wind farm wind fields with a possible potential within a multi-fidelity strategy for wind farm topology optimization. Basically, the model considers wakes as linear perturbations on the ambient non...... rotationally symmetric, and the rotor inflow fields are consistently assumed uniform. Expansion of stationary wake fields is believed to be significantly affected by meandering of wake deficits as e.g. described by the Dynamic Wake Meandering model. In the present context, this effect is approximately...

  20. Experimental analysis of the effect of vegetation on flow and bed shear stress distribution in high-curvature bends

    Science.gov (United States)

    Termini, Donatella

    2016-12-01

    The cross-sectional circulation, which develops in meandering bends, exerts an important role in velocity and the boundary shear stress redistributions. This paper considers the effect of vegetation on cross-sectional flow and bed shear distribution along a high-curvature bend. The analysis is conducted with the aid of data collected in a large-amplitude meandering flume during a reference experiment without vegetation and an experiment with vegetation on the bed. The results show that the presence of vegetation modifies the curvature-induced flow pattern and the directionality of turbulent structures. In fact, in the presence of vegetation, the turbulent structures tend to develop within and between the vegetated elements. The pattern of cross-sectional flow, modified by the presence of vegetation, affects the bed shear stress distribution along the bend so that the core of the highest value of the bed shear stress does not reach the outer bank.

  1. Measurements of American rivers clarify influences on sinuosity

    Science.gov (United States)

    Kiel, B.

    2013-12-01

    We used the National Hydrography Dataset (NHD) to measure river widths and sinuosities nationally. Sinuosities were measured over reaches scaled by river width; sinuosity values typically increase with increasing reach length. By using short reaches of ~1 meander arc length, we aim to isolate sinuosity of channels meandering within floodplains. Spatial averaging of sinuosity over the eastern half of the U.S.--where measurements are dense--produces an intuitive map that we deem more useful than individual measurements. Sinuosity exhibits the following correlations: drainage density r = -0.34; soil sand content r = 0.54; land slope r = -0.37. We submit that lateral erosion of bend outer banks in sinuous rivers is driven by a self-reinforcing mass balance cycle wherein sand eroded from outer banks sustains point bar lateral accretion, which in turn sustains outer bend lateral erosion and forces passive lateral flow migration away from the advancing point bar.

  2. Method for detection and imaging over a broad spectral range

    Science.gov (United States)

    Yefremenko, Volodymyr; Gordiyenko, Eduard; Pishko, legal representative, Olga; Novosad, Valentyn; Pishko, deceased; Vitalii

    2007-09-25

    A method of controlling the coordinate sensitivity in a superconducting microbolometer employs localized light, heating or magnetic field effects to form normal or mixed state regions on a superconducting film and to control the spatial location. Electron beam lithography and wet chemical etching were applied as pattern transfer processes in epitaxial Y--Ba--Cu--O films. Two different sensor designs were tested: (i) a 3 millimeter long and 40 micrometer wide stripe and (ii) a 1.25 millimeters long, and 50 micron wide meandering-like structure. Scanning the laser beam along the stripe leads to physical displacement of the sensitive area, and, therefore, may be used as a basis for imaging over a broad spectral range. Forming the superconducting film as a meandering structure provides the equivalent of a two-dimensional detector array. Advantages of this approach are simplicity of detector fabrication, and simplicity of the read-out process requiring only two electrical terminals.

  3. An investigation into the Gustafsson limit for small planar antennas using optimisation

    CERN Document Server

    Shahpari, Morteza; Lewis, Andrew

    2013-01-01

    The fundamental limit for small antennas provides a guide to the effectiveness of designs. Gustafsson et al, Yaghjian et al, and Mohammadpour-Aghdam et al independently deduced a variation of the Chu-Harrington limit for planar antennas in different forms. Using a multi-parameter optimisation technique based on the ant colony algorithm, planar, meander dipole antenna designs were selected on the basis of lowest resonant frequency and maximum radiation efficiency. The optimal antenna designs across the spectrum from 570 to 1750 MHz occupying an area of $56mm \\times 25mm$ were compared with these limits calculated using the polarizability tensor. The results were compared with Sievenpiper's comparison of published planar antenna properties. The optimised antennas have greater than 90% polarizability compared to the containing conductive box in the range $0.3meander line antennas is less than 50%, and resu...

  4. Textile inspired flexible metamaterial with negative refractive index

    Science.gov (United States)

    Burgnies, L.; Lheurette, É.; Lippens, D.

    2015-04-01

    This work introduces metallo-dielectric woven fabric as a metamaterial for phase-front manipulation. Dispersion diagram as well as effective medium parameters retrieved from reflection and transmission coefficients point out negative values of refractive index. By numerical simulations, it is evidenced that a pair of meandered metallic wires, arranged in a top to bottom configuration, can yield to a textile metamaterial with simultaneously negative permittivity and permeability. While the effective negative permittivity stems from the metallic grid arrangement, resonating current loop resulting from the top to bottom configuration of two meandered metallic wires in near proximity produces magnetic activity with negative permeability. By adjusting the distance between pairs of metallic wires, the electric plasma frequency can be shifted to overlap the magnetic resonance. Finally, it is shown that the woven metamaterial is insensitive to the incident angle up to around 60°.

  5. Contributions of the Stochastic Shape Wake Model to Predictions of Aerodynamic Loads and Power under Single Wake Conditions

    Science.gov (United States)

    Doubrawa, P.; Barthelmie, R. J.; Wang, H.; Churchfield, M. J.

    2016-09-01

    The contribution of wake meandering and shape asymmetry to load and power estimates is quantified by comparing aeroelastic simulations initialized with different inflow conditions: an axisymmetric base wake, an unsteady stochastic shape wake, and a large-eddy simulation with rotating actuator-line turbine representation. Time series of blade-root and tower base bending moments are analyzed. We find that meandering has a large contribution to the fluctuation of the loads. Moreover, considering the wake edge intermittence via the stochastic shape model improves the simulation of load and power fluctuations and of the fatigue damage equivalent loads. These results indicate that the stochastic shape wake simulator is a valuable addition to simplified wake models when seeking to obtain higher-fidelity computationally inexpensive predictions of loads and power.

  6. The effect of reconnection electric field on crescent and U-shaped distribution functions in asymmetric reconnection with no guide field

    Science.gov (United States)

    Bessho, N.; Chen, L.-J.; Hesse, M.; Wang, S.

    2017-07-01

    Electron distribution functions in the electron diffusion region in asymmetric reconnection without a guide field are studied by means of theory and 2-dimensional particle-in-cell (PIC) simulations. The effect of the reconnection electric field on crescent-shaped distribution functions is to broaden the thickness of the crescent. We express the thickness of the crescent as a function of field strengths, the distance from the X-line, and the time electrons spend executing meandering orbits. The electron distribution at the reconnection X-line exhibits a U-shaped structure with an opening angle in the direction of the reconnection electric field. We predict the opening angle of the U-shaped distribution by considering acceleration of the meandering electrons by the reconnection electric field. Results from particle tracing in PIC simulations and theoretical analysis agree. The above predictions provide guidance to interpret measurements by spacecraft from electron diffusion regions in asymmetric reconnection.

  7. Development and Application of Plasma Actuators for Active Control of High-Speed and High Reynolds Number Flows

    Science.gov (United States)

    Sammy, Mo

    2010-01-01

    Active flow control is often used to manipulate flow instabilities to achieve a desired goal (e.g. prevent separation, enhance mixing, reduce noise, etc.). Instability frequencies normally scale with flow velocity scale and inversely with flow length scale (U/l). In a laboratory setting for such flow experiments, U is high, but l is low, resulting in high instability frequency. In addition, high momentum and high background noise & turbulence in the flow necessitate high amplitude actuation. Developing a high amplitude and high frequency actuator is a major challenge. Ironically, these requirements ease up in application (but other issues arise).

  8. Coherent perfect absorption induced by the nonlinearity of a Helmholtz resonator.

    Science.gov (United States)

    Achilleos, V; Richoux, O; Theocharis, G

    2016-07-01

    In this work, coherent perfect absorption of sound waves induced by the nonlinear response of a Helmholtz Resonator side loaded to a waveguide, is reported. It is shown that this two-port system can perfectly absorb two high amplitude symmetric incident waves under a certain condition. For the one-sided incidence configuration, this condition leads to an absorption equal to 0.5. Experiments verify these results and are in agreement with an analytical nonlinear impedance model for the resonator. The nonlinear control of perfect absorption opens new possibilities in the design of high amplitude sound attenuators for aero-engine applications.

  9. Cultural Resources Survey of Palmetto and Coochie Revetments, Mississippi River M-326 to 315

    Science.gov (United States)

    1993-11-11

    review of the fluvial processes responsible for forming and modifying a meander belt and its associated deposits. Rather, Walker and Cant (1984) and Flores ...John Elliot, sold the 7,000 ac tract in Concordia Parish -- Black Hawk, Bally Magan [sic], and Withlacoochee [sic] Plantations -- to Lewis Trager on...Corps of Engineers, Vicksburg, Mississippi. Flores , Romero M., Frank G. Ethridge. Andrew D. Miall, William E. Galloway, and Thomas D. Fouch 1985

  10. Holocene fluvial geomorphic change in the central Mississippi Valley

    Energy Technology Data Exchange (ETDEWEB)

    Hajic, E.R. (Illinois State Museum, Springfield, IL (United States))

    1992-01-01

    Four distinct Mississippi River (MR) channel patterns are distinguished on the basis of geomorphic expression and cross-cutting relationships between the Missouri River mouth and Thebes Gap (TG). In order of decreasing age, they are (1) a multi-channeled braided system superimposed on a sandy substrate that correlates with the Kingston Terrace (KT); (2) a relatively large amplitude, large sinuosity, meandering system; (3) a smaller amplitude, smaller sinuosity, meandering system with a marked increase in associated overbank sheetwash and splays; and, (4) an island-braided pattern aligned with the modern (MR). After the (KT) formed, the (MR) had a net westward migration and episodically decreased in sinuosity. Decreasing sinuosity is possibly in response to a general decrease in sediment yield. Channel pattern changes are bracketed somewhat by available radiocarbon ages and the geomorphic location of archaeological deposit with temporally diagnostic artifacts. The KT formed between about 10,400 and 9800 B.P.; the superimposed braid pattern has fill consisting of Lake Superior source reddish brown clay deposited by large, and possibly catastrophic, floods between 9800 and 9500 B.P. The large sinuosity meandering pattern was active from before 4400 B.P. until about 2400 B.P. at the latest. It was probably initiated millennia earlier. The small sinuosity meandering pattern was initiated by about 2500 B.P. and abandoned before 1100 B.P. The geomorphic mapping is the first component of a geoarchaeological investigation to aid cultural resource management to aid cultural resource management in the central MR Valley. At the same time, it provides some constraints on the origin and age of some long-recognized landforms, such as the TG.

  11. A Loop Current experiment: Field and remote measurements

    Science.gov (United States)

    Hamilton, Peter; Lugo-Fernández, Alexis; Sheinbaum, Julio

    2016-12-01

    An overview of a new comprehensive observational study of the Loop Current (LC) in the eastern Gulf of Mexico that encompassed full-depth and near-bottom moorings, pressure-equipped inverted echo sounders (PIES) and remote sensing is presented. The study array was designed to encompass the LC from the Campeche Bank to the west Florida escarpment. This overview centers about principal findings as they pertain to mesoscale dynamics. Two companion papers provide in-depth analyses. Three LC anticyclonic eddy separation events were observed with good 3D spatial coverage over the 2½ year extent of the field study; the three separations exhibited similar processes after the LC had extended into the eastern Gulf. Large scale (∼300 km wavelength, 40-60 day periods) southward propagating meanders developed on the eastern side of the LC over deep (∼3000 m) water that were the result of baroclinic instability between the upper layer meandering jet and lower layer cyclones and anticyclones. The lower layer was only highly energetic during relatively short (∼2-3 months) intervals just prior to or during eddy detachments because of baroclinic instability. The steepening of the meanders lead to a pinch-off of LC eddies. The deep lower-layer eddies, constrained by the closed topography of the southeastern Gulf, propagated westward across the detachment zone and appear to assist in achieving separation. Small scale (∼50-100 km, periods ∼10 days) frontal eddies, observed on the western side of the LC along the Campeche Bank slope, decay over the deep water of the northern part of an extended LC, and have little influence on lower layer eddies, the east side meanders and the eddy detachment processes.

  12. Mockups of blanket cooling plates manufactured in different diffusion welding setups

    Science.gov (United States)

    Weth, A. von der; Aktaa, J.

    2009-04-01

    The high amount of energy applied to the structural elements of a future fusion power plant results in the need of using plates with meandering cooling channels. Of the different proposals [J.-F. Salavy, G. Aiello, P. Aubert, L.V. Boccaccini, M. Daichendt, G. De Dinechin, E. Diegele, L.M. Giancarli, R. Lässer, H. Neuberger, Y. Poitevin, Y. Stephan, G. Rampal, E. Rigal, J. Nucl. Mater., 386-388 (2009) 922. [1

  13. Riverine Flow Observations and Modeling: Sensitivity of Delft3D River Model to Bathymetric Variability

    Science.gov (United States)

    2011-09-30

    performed by a person walking with a GPS-equipped backpack and with an echosounder- equipped electric kayak . The meandering reach (Figure 2) is a deep (~10m...Structures in a Natural Gravel-Bed River submitted to Geophysical Research Letters. Manuscript Abstract Stream-wise, horizontal length scales and...Unmanned Surface Vehicle (USV), an Unmanned Underwater Vehicle (UUV), and some additional stationary platforms and were deployed in a number of natural

  14. The Southwestern Division: 50 Years of Service

    Science.gov (United States)

    1987-01-01

    in its channel. The San Antonio River meanders past shops and through a hotel lobby along the city’s Paseo del Rio. The Fort Worth District...and provide an additional attraction for the hotel and convention district. The project was strongly supported by the mayor, part of the city...Antiquity , 11 (April 1946): 228-256. 5. Alice Marriot , The First Corner: Indians of North America’s Dawn (New York, NY: Longmans, Green, 1960) , p. 122

  15. Patterns on House Walls in Gyirong

    Institute of Scientific and Technical Information of China (English)

    LIUXIANJIONG

    2004-01-01

    Once you have a chance to visit Jingchuan and the Mingjiang River Valley in northwestem Sichuan Province, you will find yourself in a mysterious world:Rivers meander through mountains like hada scarves, snow-capped mountains fill people with mysterious atmosphere, sutra streamers flutter in wind, pillboxes stretch their arms to hug the sky, and there are various kinds of patterns drawn on the walls of villages and mountain rocks.

  16. A Lagrangian Approach to Studying Instantaneous Plume Dispersion and Concentration Fluctations

    Science.gov (United States)

    2007-11-02

    liquid PMCH from a reservoir (a medical IV bag), through a hypodermic needle , and onto a hotplate located within the duct. The temperature of the...plume theory in which time-averaged dispersion is the result of plume meander and relative plume diffusion (Gifford 1959). Wind data near release height...Science Degree will be completed in Environmental Engineering, 1998). Note: Mark only assisted in fieldwork and data analysis during one month of the

  17. Role of eddies in the Bay of Bengal circulation and hydrography and in the distribution of nutrients and chlorophyll

    Digital Repository Service at National Institute of Oceanography (India)

    Murukesh, N.

    105 forcing, either individually or in combination. A careful examination of the bathymetry and the location of meander in the WBC rules out the possibility of topographic changes as a trigger for the instability of WBC. Based on the analysis... of eddies described above was the horizontal SLA gradient which generates the vertical shear, a necessary condition for the baroclinic instability. The horizontal SLA gradient was generated by a combination of processes. In the case of CES1 and CEF1...

  18. Low-cost inkjet antennas for RFID applications

    Science.gov (United States)

    Çiftçi, T.; Karaosmanoğlu, B.; Ergül, Ö.

    2016-03-01

    We present paper-based inkjet antennas that are fabricated by using silver-based cartridges in standard printers. In addition to their low costs, the produced antennas are flexible, environmentally friendly, and suitable for radio-frequency identification (RFID) applications. Among alternative choices, hybrid structures involving loop and parasitic meander parts are preferred and successfully combined with passive RFID chips. We also discuss main challenges in the design and fabrication of low-cost inkjet antennas and the related RFID tags.

  19. Wind Speed Estimation and Parametrization of Wake Models for Downregulated Offshore Wind Farms within the scope of PossPOW Project

    DEFF Research Database (Denmark)

    Göçmen Bozkurt, Tuhfe; Giebel, Gregor; Poulsen, Niels Kjølstad

    2014-01-01

    With increasing installed capacity, wind farms are requested to downregulate more frequently, especially in the offshore environment. Determination and verification of possible (or available) power of downregulated offshore wind farms are the aims of the PossPOW project (see PossPOW.dtu.dk). Two ...... period. The re-calibrated model has to be further parametrized to include dynamic effects such as wind direction variability and meandering also considering different averaging time scales before implemented in full scale wind farms....

  20. Environmental Features for Flood-Control Channels.

    Science.gov (United States)

    1982-07-01

    small mamals , reptiles , and amphibians. 111. Cutoffs are frequently constructed across meander loops on waterways open to commercial navigation...for stream-dwelling organisms. They also furnish habitat to reptiles , amphibians, birds, and mammals (Darnell et al. 1976; Gorman and Karr * 1978...here refers to unusually rapid bank ero- sion, lateral migration, degradation, aggradation, and the like . 23323... U ". U" U U U U • S U • U • U U .o

  1. Características geológicas, hidrológicas y del manglar en la planicie costera de Nayarit, México

    OpenAIRE

    Guadalupe de la Lanza; Norma Sánchez; Valentino Sorani

    1996-01-01

    The different geoforms of the coastal zone are consecuence of environmental changes (hydrology, climate, marine hydrodynamic and organic growth). The coastal plain of Nayarit is an example of the confluence of these factors which result in saltmarshes, lagoons, deltas, meanders, channels, swamps, all of which are bordered by high mangrove density. These characteristics coastal plain structures are exploited for human activities. In this paper the geologic, and hydrologic evolution, as well as...

  2. Evaluations of the POP Model for Navy Forecasting Use

    Science.gov (United States)

    2016-06-07

    frequency variability of the Deep Western boundary current, and Gulf Stream meander/eddy behavior. Also Lagrangian and Eulerian statistics calculated... web support are provided by Braccio (NPS). WORK COMPLETED Surface forcing fields were created from the output of the NOGAPS atmospheric model stored...the afore-mentioned web site. One of the fields saved daily is the depth of the 15-degree isotherm at about 200 m; a measure used to define the

  3. Wave Grouping of a Drifting Spiral Wave in the Presence of an External Field

    Institute of Scientific and Technical Information of China (English)

    YANG Hu-Jiang; YANG Jun-Zhong; HU Gang

    2007-01-01

    The phenomenon of wave grouping, in which the dense waves and the sparse waves can form groups in front of the spiral tip when the spiral wave is meandering, has been reported in a chemical reaction system recently. We present a method to realize the phenomenon of wave grouping by applying an external field to the system. The numerical simulations are carried out on the basis of the FitzHugh-Nagumo equations.

  4. Archaeological Geology of the Fort Hood Military Reservation, Fort Hood, Texas

    Science.gov (United States)

    1992-06-01

    respectively. Intensive convectional rain storms commonly develop at the boundary between moist tropical air from the Gulf of Mexico and the southerly flow of...Cowhouse Creek, TR2. 20 they are typically mapped as phases of the Bosque Series (McCaleb, 1985). This is probably due in large part to the difficulty in...bedload meandering stream. The West Range alluvium is capped by soils mapped as part of the Bosque Series (McCaleb, 1985). These soils typically

  5. Placement insensitive antenna for RFID, sensing, and/or communication systems

    Science.gov (United States)

    Bernhard, Jennifer T.; Ruyle, Jessica E.

    2014-06-10

    An antenna includes a ground plane having a slot. The slot may be miniaturized using a meandered slot structure or other appropriate reactive loading method as an end load to one or both ends of the slot. An edge treatment may be included on one or more edges of the ground plane or a closely spaced reflecting plane. The antenna is structured to transmit or receive a signal independently or in response to electromagnetic radiation.

  6. The lacet: A new type of the spiral wave behavior

    Energy Technology Data Exchange (ETDEWEB)

    Moskalenko, Andrey V. [Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region (Russian Federation)], E-mail: cardio@avmoskalenko.ru; Elkin, Yury E. [Institute of Mathematical Problems of Biology, Russian Academy of Sciences, 142290 Pushchino, Moscow Region (Russian Federation) and Moscow State University, Pushchino Branch, 142290 Pushchino, Moscow Region (Russian Federation)

    2009-04-15

    We found a new type of spiral wave behavior in a homogeneous two-dimensional autowave medium. In this regime, the spiral wave tip motion transforms from a two-periodic meander into one-periodic circular rotation due to spontaneous deceleration of spiral wave drift. This discovery might be useful for insight into the nature of various phenomena and, in particular, some potentially life-threatening cardiac arrhythmias.

  7. Controlling Spiral Dynamics in Excitable Media by a Weakly Localized Pacing

    Institute of Scientific and Technical Information of China (English)

    LI Bing-Wei; SUN Li-Li; CHEN Bin; YING He-Ping

    2007-01-01

    @@ Spiral dynamics controlled by a weakly localized pacing around the spiral tip is investigated. Numerical simulations show two distinct characteristics when the pacing is applied with the weak amplitude for suitable frequencies:for a rigidly rotating spiral, a transition from rigid rotation to meandering motion is observed, and for unstable spiral waves, spiral breakup can be prevented. Successfully preventing spiral breakup is relevant to the modulation of the tip trajectory induced by a localized pacing.

  8. Characterization and comparative evaluation of novel planar electromagnetic sensors

    OpenAIRE

    Mukhopadhyay, S. C.; Gooneratne, C. P.; Sen, Gupta G.; Yamada, Sotoshi

    2005-01-01

    The characterization of three types of novel planar electromagnetic sensors: 1) meander; 2) mesh; and 3) interdigital configuration, has been studied and their comparative performance has been evaluated based on their areas of applications. All of them are suitable for inspection and evaluation of system properties without destroying them. The experiments on fabricated sensors have been conducted and the results are presented here. The target application is to use a mixture of different types...

  9. Millennial-scale climatic fluctuation in the fluvial record during MIS3: Very high-resolution seismic images from NE Hungary

    Science.gov (United States)

    Cserkész-Nagy, Ágnes; Sztanó, Orsolya

    2016-12-01

    Alluvial architectures of a meandering river existing in MIS3 were observed on very high-resolution (VHR) single-channel waterborne seismic profiles, 20-30 m below the Tisza River in the Pannonian Basin (Hungary). The study investigated the spatial and temporal variations of two, more than 2 km-long continuous series of inclined reflections interpreted as laterally accreted point bar complexes. The phases of natural meander migration were reconstructed in 3D based on the changes in the geometry and dip of the inclined reflections. A channel-forming discharge curve extending over approximately 2.5 ky was calculated by using paleo-width and depth data derived from the lateral accretion surfaces. Systematic analysis of the geometrical variations coupled with the discharge curve evaluation on each point bar complexes indicates millennial-scale discharge fluctuations 40-50 ky ago, to that the river responded principally by incision and infilling. The primary periodicity, comparable to the sub-Milankovitch cycles, is superimposed by shorter periods: ca. 500-year cycles reflect the phases of unidirectional meander development, while the smallest ones reflect the recurrence interval (150-200 years) of the highest floods. River-bed incisions happened step-by-step related to extreme floods, when the meander development also changed. The smaller-scale and more rapid fluctuations within a development unit were represented in variations of the channel width. Although the poor geochronology of the sandy fluvial deposits cannot allow any direct correlation to the climatostratigraphic events, the millennial-scale climate variations of MIS3 were pronouncedly characteristic in the discharge fluctuations.

  10. A Field Guide to the Identification of the Ordinary High Water Mark (OHWM) in the Arid West Region of the Western United States: A Delineation Manual

    Science.gov (United States)

    2008-08-01

    channel associated with discharge events. (Note: There may be aggradation or degradation after step 2. ) 14 ERDC/CRREL TR-08-12 Figure 11. Pre...overbank flows emanating from aggrading main channel 16 ERDC/CRREL TR-08-12 Single-thread channels with adjacent floodplains – Meandering...relative to sediment supplied to reach – Channel widening with bank destabilization – Aggradation due to decrease in capacity to transport sediment

  11. A Framework and Strategies for Determining Reference Conditions for Streams with Legacy Sediments on Military Installations

    Science.gov (United States)

    2009-03-01

    transport regime downstream can result in increased scour or aggradation of sediment upstream (Rosgen 1996; Schumm, Har- vey, and Watson 1984; Shields...within their floodplains. A ERDC/CERL TR-09--08 12 stable sediment regime implies the stream does not have net erosion or aggradation within the...channel stability, deposition patterns, aggradation /degradation trends, altered channel features, and meander patterns. In addition, com- panion

  12. Placement insensitive antenna for RFID, sensing, and/or communication systems

    Energy Technology Data Exchange (ETDEWEB)

    Bernhard, Jennifer T.; Ruyle, Jessica E.

    2014-06-10

    An antenna includes a ground plane having a slot. The slot may be miniaturized using a meandered slot structure or other appropriate reactive loading method as an end load to one or both ends of the slot. An edge treatment may be included on one or more edges of the ground plane or a closely spaced reflecting plane. The antenna is structured to transmit or receive a signal independently or in response to electromagnetic radiation.

  13. Area Report. Developments in Microwave Antennas and Applications in Sweden, Denmark, and Norway.

    Science.gov (United States)

    1980-12-31

    phase shifters that used a meander line on a ferrite substrate. There was a transmitter- receiving circulator, a switch , and an isolator, and the...and dioA phase shifter developments. In one version, the array was active and used FET X-band amplifiers that were developed by the MI, and latching ...final power output was 1 Watt CW. Ferrite materials are actually being made at FOA for their own use. The Passive Circuit Section is headed by J. Loren

  14. Fluvial responses to late Quaternary climate change in the Shiyang River drainage system, western China

    Science.gov (United States)

    Gao, Hongshan; Li, Zongmeng; Pan, Baotian; Liu, Fenliang; Liu, Xiaopeng

    2016-04-01

    As a drainage system located in arid western China, the Shiyang River, combined with considerable fluvial strata and landform information, provides an environmental context within which to investigate fluvial responses to late Quaternary climate change. Sedimentological analysis and optically stimulated luminescence (OSL) dating enabled us to reconstruct the processes and fluvial styles of three sedimentary sequences of the Shagou and Hongshui rivers in the Shiyang drainage system. Our results present a variety of river behaviors during the late Quaternary in these areas. In the upstream Shiyang River, Zhangjiadazhuang (ZJDZ) profile of the Shagou was dominated by aggradation and a meandering channel pattern at 10.6-4.2 ka, while a noticeable channel incision occurred at ~ 4.2 ka followed by lateral channel migration. In the downstream Shiyang River, Datugou (DTG) profile of the Hongshui was an aggrading meandering river from 39.7 to 7.2 ka while channel incision occurred at 7.2 ka. Another downstream profile, Wudunwan (WDW) of the Hongshui was also characterized by aggradation from 22.4 to 4.8 ka; however, its channel pattern shifted from braided to meandering at ~ 13 ka. A discernable downcutting event occurred at ~ 4.8 ka, followed by three channel aggradation and incision episodes prior to 1.8 ka. The last 1.8 ka has been characterized by modern channel and floodplain development. The fluvial processes and styles investigated have a close correlation with late Quaternary climate change in the Shiyang River drainage. During cold phases, the WDW reach was dominated by aggradation with a braided channel pattern. During warm phases, the rivers that we investigated were also characterized by aggradation but with meandering channel patterns. Channel incision events and changes of fluvial style occurred mainly during climate transitions.

  15. Use of a Three-Dimensional Reactive Solute Transport Model for Evaluation of Bioreactor Placement in Stream Restoration.

    Science.gov (United States)

    Cui, Zhengtao; Welty, Claire; Gold, Arthur J; Groffman, Peter M; Kaushal, Sujay S; Miller, Andrew J

    2016-05-01

    A three-dimensional groundwater flow and multispecies reactive transport model was used to strategically design placement of bioreactors in the subsurface to achieve maximum removal of nitrate along restored stream reaches. Two hypothetical stream restoration scenarios were evaluated over stream reaches of 40 and 94 m: a step-pool scenario and a channel re-meandering scenario. For the step-pool scenario, bioreactors were placed at locations where mass fluxes of groundwater and nitrate were highest. Bioreactors installed over 50% of the total channel length of a step-pool scenario (located to intercept maximum groundwater and nitrate mass flux) removed nitrate-N entering the channel at a rate of 36.5 kg N yr (100 g N d), achieving about 65% of the removal of a whole-length bioreactor. Bioreactor placement for the re-meandering scenario was designed using a criterion of either highest nitrate mass flux or highest groundwater flux, but not both, because they did not occur together. Bioreactors installed at maximum nitrate flux locations (53% of the total channel length) on the western bank removed nitrate-N entering the channel at 62.0 kg N yr (170 g N d), achieving 85% of nitrate-N removal of whole-length bioreactors for the re-meandering scenario. Bioreactors installed at maximum groundwater flux locations on the western bank along approximately 40% of the re-meandering channel achieved about 65% of nitrate removal of whole-length bioreactors. Placing bioreactors at maximum nitrate flux locations improved denitrification efficiency. Due to low groundwater velocities, bioreactor nitrate-N removal was found to be nitrate limited for all scenarios.

  16. The Kuroshio Transport East of Taiwan and the Sea Surface Height Anomaly from the Interior Ocean

    Institute of Scientific and Technical Information of China (English)

    LIU Wei; LIU Qinyu; JIA Yinglai

    2004-01-01

    The relationship between the Kuroshio transport to the east of Taiwan and the SSHA(Sea Surface Height Anomaly)field is studied based on the World Ocean Circulation Experiment(WOCE)PCM-1 moored current meter array observation, the satellite altimeter data from the MSLA(Map of Sea Level Anomaly)products merged with the ERS and TOPEX/POSEIDON(T/P)data sets, and the WOCE satellite-tracked drifting buoy data. It is confirmed that the Kuroshio transport across PCM-1 array highly correlates with the SSHA upstream(22°-24°, 121.75°-124°E). The SSHA is not locally generated by the developed Kuroshio meandering but is from the interior ocean and is propagating westward or northwestward. During the period from October 1992 to January 1998, two events of the northwestward propagating negative SSHA occurred, during which the SSHA merged into the Kuroshio and caused the remarkable low transport events in contrast to the normal westward propagating negative SSHA. It is also shown that the lower Kuroshio transport event would be generated in different ways. The negative anomaly in the upstream of PCM-1 array can reduce the Kuroshio transport by either offshore or onshore Kuroshio meandering. The positive anomaly, which is strong enough to detour the Kuroshio, can cause an offshore meandering and a low transport event at the PCM-1 array.

  17. Analyzing the effects of historical and recent floods on channel pattern and the environment in the Lower Omo basin of Ethiopia using satellite images and GIS

    Science.gov (United States)

    Ayalew, Lulseged

    2009-10-01

    Previous accounts and recent observations indicate that the pattern and geometry of the Omo River meanders in the Lower Omo basin of Ethiopia had already been established in earlier times by large floods that took place after extended periods of drought. The cross-sectional changes resulted from floods in the nineteenth and twentieth centuries, were then simply limited to small degree channel widening and entrenchment, and floodplain erosion and deposition. The effects of the August 2006 flood, although widespread and destructive for the environment, were also modest as far as adjusting the channel pattern is concerned. Changes in channel profiles at short-term scales usually come in the form of aggradation and degradation. Interpretations of satellite images taken before and after the flood showed the accumulation of coarse sediments in the channel. There are also some sporadic indications for an increase in channel width. Widening in response to high amount of discharges can generally be expected during floods. Besides, signs of channel shortening were observed in some places. Apart from these minor changes, the dimension of meandering segments or the outline of the entire meander belt, and the basic morphology of the channel remained unaffected.

  18. Geophysical evidence for a major palaeochannel within the Obosum Group of the Volta Basin, Northern Region, Ghana

    Science.gov (United States)

    Jessell, Mark; Boamah, Kwame; Duodu, John Agyei; Ley-Cooper, Yusen

    2015-12-01

    We have identified a 230 km long palaeochannel cutting through the sediments of the Obosum Group within the Volta Basin, Ghana. The channel is visible in regional airborne magnetic data as a pair of parallel magnetic anomalies which we interpret to be lateral terrace placer deposits of magnetite or maghemite and show both meandering and braided geometries. The palaeochannel is also visible in the airborne radiometric data for part of its length, as well as in airborne electromagnetic data, where it is marked by a zone of low conductivity. The meanders have a wavelength of around 20 km and together with the 2 km spacing between magnetic anomalies, suggest a major palaeo-river system, of as yet unknown age, although based on published detrital zircon ages for the host sediments and geomorphological arguments it is probably between 509 ± 68 and 45 Ma, and is comparable in size to the modern-day Niger River. Given the known occurrences of alluvial gold and diamonds in Ghana, and the general prospectivity of meandering and braided rivers systems, we believe the region has exploration potential for a range of economically valuable minerals, and could also potentially host a shallow aquifer.

  19. Energetic particle transport across the mean magnetic field: before diffusion

    CERN Document Server

    Laitinen, T

    2016-01-01

    Current particle transport models describe the propagation of charged particles across the mean field direction in turbulent plasmas as diffusion. However, recent studies suggest that at short time-scales, such as soon after solar energetic particle (SEP) injection, particles remain on turbulently meandering field lines, which results in non-diffusive initial propagation across the mean magnetic field. In this work, we use a new technique to investigate how the particles are displaced from their original field lines, and quantify the parameters of the transition from field-aligned particle propagation along meandering field lines to particle diffusion across the mean magnetic field. We show that the initial decoupling of the particles from the field lines is slow, and particles remain within a Larmor radius from their initial meandering field lines for tens to hundreds of Larmor periods, for 0.1-10 MeV protons in turbulence conditions typical of the solar wind at 1~AU. Subsequently, particles decouple from th...

  20. EBG combined isolation slots with a bridge on the ground for noise suppression

    Science.gov (United States)

    Shi, Ling-Feng; Wei, Zheng; Wang, Cong-Rui

    2016-10-01

    In this paper, a coplanar electromagnetic bandgap (EBG) structure is presented to realise with L-bridge unit cell on the power plane that is combined isolation slots with straight/meander-bridge on the ground plane. The proposed structure with meander-bridge on the ground plane possesses an ultra-wide band gap from 0.22 GHz to 20 GHz with isolation below -30 dB, which is remarkable better than traditional EBG. The lumped equivalent-circuit model for the structure is presented and analysed to explain the mechanism of the improvement of noise suppression. The cut-off frequency for the proposed structure is obtained by theoretical analysis. It is shown that the increase of equivalent inductance of the bridge influences the cut-off frequency. The meander-bridge on the ground plane is adopted to broaden the stopband and significantly enhance the suppression depth. The validity of the presented structure is verified by the simulation compared to the measurement.

  1. Step-step interactions on GaAs (110) nanopatterns

    Energy Technology Data Exchange (ETDEWEB)

    Galiana, B.; Benedicto, M.; Tejedor, P. [Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain)

    2013-01-14

    The step-step interactions on vicinal GaAs (110) surface patterns have been extracted from the quantitative analysis of the terrace width distribution (TWD). We have specifically studied the interactions in near-equilibrium faceting and kinetics-driven step bunching and meandering formed by spontaneous self-organization or through the modification of GaAs growth kinetics by atomic hydrogen. We show that the experimental TWDs determined from atomic force microscopy measurements can be accurately described by a weighed sum of a generalized Wigner distribution and several Gaussians. The results of our calculations indicate that straight facets are formed during high temperature homoepitaxy due to attractive interactions between [110] steps. At low temperatures, steady state attractive interactions in [110] step bunches are preceded by a transition regime dominated by entropic and energetic repulsions between meandering [11n]-type steps (n {>=} 2), whose population density exceeds that of the [110] bunched steps. In addition, it has been found that atomic H reduces the attractive interactions between [110] bunched steps and enhances entropic and dipole-induced energetic repulsions between H-terminated [11n] steps through the inhibition of As-As bond formation at step edges. Our analysis has evidenced a correlation between the value of the adjustable parameter that accounts in our model for the specific weight of the secondary peaks in the TWD ({beta}) and the extent of transverse meandering on the vicinal surface.

  2. Multiplication of shearless barriers for chaotic transport in order to improve confined plasmas in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Caroline G.L.; Roberto, M. [Instituto Tecnologico de Aeronautica (ITA/CTA), Sao Jose dos Campos, SP (Brazil); Carvalho, R. Egydio de [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), SP (Brazil); Caldas, I.L. [Universidade de Sao Paulo (USP), SP (Brazil)

    2012-07-01

    Full text: We present a study that deals with meandering curves which arise after the reconnection process (or overlap) of resonances (1), that occurs only in non-twist discrete maps (2). Meandering curves formed by this kind of process play the role of barriers for chaotic transport in phase space, because inside the meandering region there is a special torus, called shearless torus, known as the strongest torus in a dynamical system (1). We introduce an extra perturbation in the Standard Non-twist Map (3), and we call this new map Labyrinthic Standard Non-twist Map (4). The labyrinthic map proposed in this work shows multiple reconnection processes of resonances, presenting multiple barriers for chaotic transport. Having applications in important areas such as the physics of thermonuclear plasmas confined in tokamaks for the extraction of clean energy. (1) D. del-Castillo-Negrete, J. M. Greene, P. J. Morrison, Physica D 91, 1 (1996) (2) A.J. Lichtenberg and M.A. Lieberman, Regular and Chaotic Dynamics (Springer, New York, 1992) (3) D. Del-Castillo-Negrete and P. J. Morrison, Phys. Fluids A 5, 948 (1993) (4) Caroline G. L. Martins; R. Egydio de Carvalho; I. L. Caldas; M. Roberto. Labyrinthic standard non-twist map. Journal of Physics A, Mathematical and Theoretical, v. 44, p. 045102 (2011). (author)

  3. Characterization of the critical current and physical properties of superconducting epitaxial NbTiN sub-micron structures

    Energy Technology Data Exchange (ETDEWEB)

    Klimov, A., E-mail: aklimov@ite.waw.pl [Institute of Electron Technology, Al. Lotników 32/46, 02-668 Warsaw (Poland); Słysz, W.; Guziewicz, M. [Institute of Electron Technology, Al. Lotników 32/46, 02-668 Warsaw (Poland); Kolkovsky, V.; Zaytseva, I.; Malinowski, A. [Institute of Physics Polish Academy of Science, Al. Lotników 32/46, 02-668 Warsaw (Poland)

    2017-05-15

    Highlights: • This manuscript presents investigation of the critical current dependence of Nb(Ti)N nanostructured superconducting single photon detectors (SNSPD) in function of temperature and applied magnetic field. • Presented results are complimentary and compared with the same data received for submicron-wide single bridge Nb(Ti)N structures. • Our data demonstrate significant influence of local constrictions on physical properties of our SNSPD detectors. - Abstract: Measurements of critical current in NbTiN as a function of applied magnetic field and temperature are reported for two samples: 700-nm-wide bridge and 100-nm-wide meander. In 700-nm-wide NbTiN bridge we pinpointed the limiting factors for the critical current density to be current-driven vortex de-pinning at low temperatures and thermally activated flux flow closer to the transition temperature. In 100-nm-wide NbTiN meander we found phase slips activation, accompanied by hotspots formation at all measured temperatures. These two types of structures demonstrate different dependence of the critical current on the applied magnetic field. Although our NbTiN meander structures has high de-pairing critical current densities ∼10{sup 7} A/cm{sup 2} at low temperatures, the real critical currents are smaller due to the presence of the local constrictions.

  4. Using Pressure and Alteration Indicators to Assess River Morphological Quality: Case Study of the Prahova River (Romania

    Directory of Open Access Journals (Sweden)

    Gabriela Ioana-Toroimac

    2015-06-01

    Full Text Available River morphological quality assessment, derived from quantification of human pressures as well as river channel alteration, is a demand of the Water Framework Directive (WFD in terms of integrating hydromorphological elements in defining ecological status. Our study’s aim is to contribute to the hydromorphological evaluation by proposing indicators and separating classes, based on a revisited Morphological Quality Index (rMQI protocol. The rMQI is based on 12 indicators of human pressures, 10 indicators of channel form adjustments, and 11 indicators of functionality. The rMQI scoring system allows for the quantification of changes when compared to reference conditions, be they undisturbed or nearly undisturbed by human interventions, with absent channel adjustments and a functioning natural river style. We used the lower, meandering sector of the Prahova River to demonstrate our assessment methodology. The Lower Prahova River suffers from a minor local intervention and a diminishing intensity of fluvial processes specific to a meandering style. Meanders geometry was affected by significant changes that included a decrease in the radius of curvature, width and width–to–mean–depth ratio. We concluded that the Lower Prahova River has a good morphological quality, which is rated as second class on a scale of five levels, from natural to severely modified. We recommend an improvement in the hydromorphological evaluation protocol in Romania by additional indicators for morphological alterations specific to each channel pattern.

  5. Spring upper warm water of the Nansha Islands sea area in the South China Sea and the numerical study on its dynamic mechanism

    Institute of Scientific and Technical Information of China (English)

    CAI Shuqun; LONG Xiaomin; WANG Sheng'an; CHEN Rongyu

    2006-01-01

    According to the satellite remote sensing monthly mean sea surface temperature data and in situ observational Conductivity-Temperature-Depth data, it is shown that in spring, at the upper layer to the west of Palawan Island, there exists a relatively weak warm water tongue which is distinctly different from the cold water southeast of the Balabac Strait.The relative temperature difference between the warm and cold water reduces gradually from winter to spring. P-vector method is employed to calculate the current field based on the in situ observational data,which shows that the warm water is within an anticyclonic meander. Based on the remote sensing wind stress during the observational period, a coupled single-layer/two-layer model is employed to study the dynamic mechanism of this anticyclonic meander current field corresponding to the warm water tongue.According to the numerical results, it is suggested that this anticyclonic meander could be mainly the residue of the winter anticyclonic eddy, rather than formed by the inflow water from the Sulu Sea via the Balabac Strait.

  6. Reducing cross-sectional data using a genetic algorithm method and effects on cross-section geometry and steady-flow profiles

    Science.gov (United States)

    Berenbrock, Charles E.

    2015-01-01

    Reduction of cross-sectional data using a genetic algorithm method, and the effects of data reduction on channel geometry and steady-flow profiles, were analyzed. Two reduction methods─standard and genetic algorithms─were used to reduce cross-sectional data from the Kootenai River in northern Idaho. Cross sections that are representative of meander, straight, braided, and canyon reaches were used to evalutate the reduction methods. Visual and hydraulic analyses were used to assess the methods. The genetic algorithm-reduced cross sections approximated the shape of the original cross sections better than the standard-reduced cross sections. A greater number of cross-sectional data points were needed for reduced cross sections in the straight reach, and even more in the braided reach, because a greater amount of data points are needed to adequately define cross sections that have greater topographic varability. For the genetic algorithm-reduction method, about 40 data points were needed to adequately define the shape of a reduced cross section in the braided reach compared to 10 to 20 data points in the meander and canyon reaches. The standard-reduction method needed about 70 data points for the braided reach and more than 30 points for the meander and canyon reaches. The genetic algorithm can effectively reduce data while staying within the threshold set by the maximum number of points to be included in the reduced dataset.

  7. Development of an OSL chronology for Late Pleistocene channel belts in the lower Mississippi valley, USA

    Science.gov (United States)

    Rittenour, Tammy M.; Goble, Ronald J.; Blum, Michael D.

    2005-12-01

    The broad alluvial valley of the lower Mississippi River contains large channel belts for which age control has been limited by the lack of organic material for radiocarbon dating and deposit ages greater than the limit of radiocarbon. In order to produce a detailed chronology of fluvial evolution, samples for optical dating were collected from Late Pleistocene channel-belt deposits. Quartz sand was analyzed using the coarse-grained, single-aliquot regenerative-dose (SAR) technique. Samples showed little evidence of partial bleaching, and optical ages are for the most part consistent with the available radiocarbon and relative age constraints. Optical ages range from 85 to 11 ka and, along with geomorphic and stratigraphic relationships, indicate that the Mississippi River was meandering during the end of the last interglacial (85-83 ka) and switched to a braided regime by 64-50 ka during initial marine oxygen isotope stage (OIS) 4/3 glaciation of the upper Mississippi drainage basin. The Mississippi River switched back to a meandering regime after formation of the youngest braid belt at 11 ka. The 69 optical ages presented here provide the first detailed chronology of lower Mississippi valley braid-belt and Pleistocene meander-belt formation, and provide an example of the utility of optical dating in fluvial settings where material for radiocarbon dating is scarce.

  8. A palaeolithic map from 13,660 calBP: engraved stone blocks from the Late Magdalenian in Abauntz Cave (Navarra, Spain).

    Science.gov (United States)

    Utrilla, P; Mazo, C; Sopena, M C; Martínez-Bea, M; Domingo, R

    2009-08-01

    An engraved block from the cave of Abauntz is interpreted as a Magdalenian map in which the actual surrounding landscape, including mountains, rivers, and ponds, is represented. Some possible routes or avenues of access to different parts of the geography are also engraved on the landscape. The engraving seems to reproduce the meandering course of a river crossing the upper part of side A of the block, joined by two tributaries near two mountains. One of these is identical to the mountain that can be seen from the cave, with herds of ibex depicted on its hillsides, on both sides of the gorge in front of which the cave of Abauntz is strategically located. In the southern part of the gorge, there is a completely flat area where the watercourses slow down, forming meanders and flooding in springtime. The following elements are also represented on the block: tangles of concentric strokes and bundles of lines forming very marked meanders. In short, all of these engravings could be a sketch or a simple map of the area around the cave. It could represent the plan for a coming hunt or perhaps a narrative story of one that had already happened. This paper is provided in the context of recent discussions on early modern human capacities of spatial awareness, planning, and organized hunting.

  9. “ Sedimentology and geochemistry of recent alluvium of the wadi Beht mean (Furrow south western Rif, Morocco: dynamics of implementation and hydrological and climatic meanings ”

    Directory of Open Access Journals (Sweden)

    Ahmed LAABIDI

    2016-05-01

    Full Text Available The watershed of the river Beht is located northwest of Morocco and occupies the southwestern part of the Sebou basin. This study focuses on the sedimentological and geochemical analysis of current alluvial floodplain and meandering filling abandoned Middle Beht. The results revealed that the sediments exhibit an alkaline pH, low levels of carbonates, low values of the electrical conductivity and relatively high contents of organic matter mostly in the finest sediment. Deposits are organized in grano-decreasing repetitive elementary sequences much more expressed and fines in meandering filling abandoned deposits, which function as ephemeral lakes, as in those of the floodplain. They are the expression of the sedimentological variation of hydrodynamics related to the succession of flood-related flood recession cycles themselves with climate change. They are set up on the often rocky deposits texture background meandering channels and bars. The sequence of these basic sequences, sandy-silty clay at the base and silty-sandy clay on top, gives larger sequences grano-decreasing.

  10. Dual-band LTCC antenna based on 0.95Zn2SiO4-0.05CaTiO3 ceramics for GPS/UMTS applications

    Institute of Scientific and Technical Information of China (English)

    窦刚; 李玉霞; 郭梅

    2015-01-01

    In this paper, we present a compact low-temperature co-fired ceramic (LTCC) dual-band antenna by using the elec-tromagnetic coupling effect concept for global positioning system (GPS) and universal mobile telecommunication system (UMTS) applications. The overall dimension of the antenna is 8.6 mm × 13.0 mm × 1.1 mm. It consists of double meander lines and a via hole line. The top meander line operates at the upper band, and the bottom radiating patch is designed for the lower band. The via-hole line is employed to connect the double meander lines. Because of the effect of the coupled line, total dimension of the proposed antenna is greatly reduced. With the 2.5:voltage standing wave ratio (VSWR) impedance bandwidth definition, the lower and upper bands have the bandwidths of 110 MHz and 150 MHz, respectively. The pro-posed antenna is successfully designed, simulated, and analyzed by a high frequency structure simulator (HFSS). And the antenna is manufactured by using the 0.95Zn2SiO4-0.05CaTiO3 ceramics (εr=7.1, tanδ =0.00038) that is prepared by ourselves. The results show that the antenna is compact, efficient, and of near omnidirectional radiation pattern.

  11. Lateral migration of the Middle Sacramento River, California

    Science.gov (United States)

    Brice, James Coble

    1977-01-01

    Rates and processes of lateral erosion were studied for the middle Sacramento River between Chico Landing and Colusa, Calif. , a river distance of about 50 miles which is bordered by valuable agricultural land. The study is based on comparison of maps made during 1867-1949 and on aerial photographs made during 1924-74. Meander loops migrate by downstream translation in a direction nearly perpendicular to the loop axis. Loops are cut off by straight or diagonal chutes across the meander neck. The sinuosity of the river has gradually decreased from a value of 1.56 in 1896 to 1.35 in 1974. The morphology and curvature of meander loops cut off before white settlers came to the area indicate that the river was more stable, as well as more sinuous , then than now; subsequent morphologic changes are attributed mainly to the clearing of riparian vegetation and the effects of levees in reducing the area of overflow. The bank-erosion is 1.82 acres per year per stream mile or about 15 feet per year per stream foot for the period 1896-1974. (Woodard-USGS)

  12. Phase Matters: Responding to and Learning about Peripheral Stimuli Depends on Hippocampal ? Phase at Stimulus Onset

    Science.gov (United States)

    Nokia, Miriam S.; Waselius, Tomi; Mikkonen, Jarno E.; Wikgren, Jan; Penttonen, Markku

    2015-01-01

    Hippocampal ? (3-12 Hz) oscillations are implicated in learning and memory, but their functional role remains unclear. We studied the effect of the phase of local ? oscillation on hippocampal responses to a neutral conditioned stimulus (CS) and subsequent learning of classical trace eyeblink conditioning in adult rabbits. High-amplitude, regular…

  13. Neural dynamics during anoxia and the "wave of death"

    NARCIS (Netherlands)

    Zandt, Bas-Jan; Zandt, B.; ten Haken, Bernard; van Dijk, J. Gert; van Putten, Michel Johannes Antonius Maria

    2011-01-01

    Recent experiments in rats have shown the occurrence of a high amplitude slow brain wave in the EEG approximately 1 minute after decapitation, with a duration of 5–15 s (van Rijn et al, PLoS One 6, e16514, 2011) that was presumed to signify the death of brain neurons. We present a computational

  14. Basement structure beneath the innershelf off Mahabalipuram to Palar River, east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Murthy, K.S.R.; Venkateswarlu, K.; Rao, T.C.S.

    Magnetic data along three coastal parallel profiles over the innershelf (30-50 m water depth) off Mahabalipuram recorded short wavelength and high amplitude (peak to peak of the order of 200-700 nT) anomalies. Two linear NW-SE trends were delineated...

  15. Singing mitigation in corrugated tubes with liquid injection

    NARCIS (Netherlands)

    Belfroid, S.P.C.; Golliard, J.; Vijlbrief, O.

    2013-01-01

    Pipes with a corrugated inner surface, as used in flexible pipes for gas production and transport, can generate a high amplitude tonal sound (singing). Small quantities of liquid can result in a significant amplitude reduction or total mitigation of this sound production. To evaluate different poten

  16. Kink shape solutions of the Maxwell-Lorentz system

    DEFF Research Database (Denmark)

    Sørensen, Mads Peter; Webb, G.M.; Brio, M.

    2005-01-01

    In the limit of high amplitude oscillating electromagnetic fields, a sequence of kink antikink shaped optical waves has been found in the Maxwell's equations coupled to a single Lorentz oscillator and with Kerr nonlinearity. The individual kinks and antikinks result from a traveling wave assumpti...

  17. The Dispersion Relation for the 1/sinh(exp 2) Potential in the Classical Limit

    Science.gov (United States)

    Campbell, Joel

    2009-01-01

    The dispersion relation for the inverse hyperbolic potential is calculated in the classical limit. This is shown for both the low amplitude phonon branch and the high amplitude soliton branch. It is shown these results qualitatively follow that previously found for the inverse squared potential where explicit analytic solutions are known.

  18. Effect of Vibration Training on Anaerobic Power and Quardroceps Surface EMG in Long Jumpers

    Science.gov (United States)

    Liu, Bin; Luo, Jiong

    2015-01-01

    Objective: To explore the anaerobic power and surface EMG (sEMG) of quardrocep muscle in lower extremities after single vibration training intervention. Methods: 8 excellent male long jumpers voluntarily participated in this study. Four intervention modes were devised, including high frequency high amplitude (HFHA,30Hz,6mm), low frequency low…

  19. Resistance index of frostbite as a predictor of cold injury in arctic operations

    NARCIS (Netherlands)

    Daanen, H.A.M.; Struijs, N.R. van der

    2005-01-01

    Cold-induced vasodilation (CIVD) is mentioned as a mechanism that may prevent the occurrence of local cold injuries. The magnitude of the CIVD reaction differs considerably between subjects and there were some indications that those subjects with a fast CIVD reaction with high amplitude had a reduce

  20. The effects of the specific 5HT(4) receptor agonist, prucalopride, on colonic motility in healthy volunteers

    NARCIS (Netherlands)

    De Schryver, AMP; Andriesse, GI; Samsom, M; Smout, AJPM; Gooszen, HG; Akkermans, LMA

    2002-01-01

    Background: Prucalopride is a selective and specific 5-hydroxytryptamine(4) receptor agonist that is known to increase stool frequency and to accelerate colonic transit. Aim: To investigate the effect of prucalopride on high-amplitude propagated contractions and segmental pressure waves in healthy v