bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiplex transmission system for gate drive signals of inverter circuit using surface acoustic wave filters
Authors: Suzuki Akifumi , Ueda Kensuke , Goka Shigeyoshi , Wada Keiji , Kakio Shoji 
Published: May 2016

Abstract
We propose and fabricate a multiplexed transmission system based on frequency-division multiple access (FDMA) with surface acoustic wave (SAW) filters. SAW filters are suitable for use in wide-gap switching devices and multilevel inverters because of their capability to operate at high temperatures, good electrical isolation, low cost, and high reliability. Our proposed system reduces the number of electrical signal wires needed to control each switching device and eliminates the need for isolation circuits, simplifying the transmission system and gate drive circuits. We successfully controlled two switching devices with a single coaxial line and confirmed the operation of a single-phase half-bridge inverter at a supply voltage of 100 V, and the total delay time to control the switching devices was less than 2.5 µs. Our experimental results validated our proposed system.
High resolution wavenumber analysis for investigation of arterial pulse wave propagation
Authors: Hasegawa Hideyuki , Sato Masakazu , Irie Takasuke 
Published: May 2016

Abstract
The propagation of the pulse wave along the artery is relatively fast (several m/s), and a high-temporal resolution is required to measure pulse wave velocity (PWV) in a regional segment of the artery. High-frame-rate ultrasound enables the measurement of the regional PWV. In analyses of wave propagation phenomena, the direction and propagation speed are generally identified in the frequency-wavenumber space using the two-dimensional Fourier transform. However, the wavelength of the pulse wave is very long (1 m at a propagation velocity of 10 m/s and a temporal frequency of 10 Hz) compared with a typical lateral field of view of 40 mm in ultrasound imaging. Therefore, PWV cannot be identified in the frequency-wavenumber space owing to the low resolution of the two-dimensional Fourier transform. In the present study, PWV was visualized in the wavenumber domain using phases of arterial wall acceleration waveforms measured by high-frame-rate ultrasound.
The transcriptional activator GaaR of Aspergillus niger is required for release and utilization of d‐galacturonic acid from pectin
Authors: Alazi Ebru , Niu Jing , Kowalczyk Joanna E. , Peng Mao , Aguilar Pontes Maria Victoria , van Kan Jan A. L. , Visser Jaap , de Vries Ronald P. , Ram Arthur F. J. 
Published: May 2016

We identified the d‐galacturonic acid (GA)‐responsive transcriptional activator GaaR of the saprotrophic fungus, Aspergillus niger, which was found to be essential for growth on GA and polygalacturonic acid (PGA). Growth of the ΔgaaR strain was reduced on complex pectins. Genome‐wide expression analysis showed that GaaR is required for the expression of genes necessary to release GA from PGA and more complex pectins, to transport GA into the cell, and to induce the GA catabolic pathway. Residual growth of ΔgaaR on complex pectins is likely due to the expression of pectinases acting on rhamnogalacturonan and subsequent metabolism of the monosaccharides other than GA.
First principles model of carbonate compaction creep
Authors: Keszthelyi Daniel , Dysthe Dag Kristian , Jamtveit Bjørn 
Published: May 2016

AbstractRocks under compressional stress conditions are subject to long‐term creep deformation. From first principles we develop a simple micromechanical model of creep in rocks under compressional stress that combines microscopic fracturing and pressure solution. This model was then upscaled by a statistical mechanical approach to predict strain rate at core and reservoir scale. The model uses no fitting parameter and has few input parameters: effective stress, temperature, water saturation porosity, and material parameters. Material parameters are porosity, pore size distribution, Young's modulus, interfacial energy of wet calcite, the dissolution, and precipitation rates of calcite, and the diffusion rate of calcium carbonate, all of which are independently measurable without performing any type of deformation or creep test. Existing long‐term creep experiments were used to test the model which successfully predicts the magnitude of the resulting strain rate under very different effective stress, temperature, and water saturation conditions. The model was used to predict the observed compaction of a producing chalk reservoir.
Constraints on the heterogeneity spectrum of Earth's upper mantle
Authors: Mancinelli Nicholas , Shearer Peter , Liu Qinya 
Published: May 2016

AbstractWe constrain the heterogeneity spectrum of Earth's upper mantle at scales from a few kilometers to tens of thousands of kilometers using observations from high‐frequency scattering, long‐period scattering, and tomography. Tomography and high‐frequency scattering constraints are drawn from previous studies, but constraints on mantle heterogeneity at intermediate scales (5–500 km) are lacking. To address this, we stack ∼15,000 long‐period P coda envelopes to characterize the globally averaged scattered wavefield at periods from 5 to 60 s and at ranges from 50 to 98°. To fit these observations, we consider models of random mantle heterogeneity and compute the corresponding global wavefield using both a ray theoretical “seismic particle” approach and full spectral element simulations. Von Kármán random media distributed throughout the uppermost 600 km of the mantle with a = 2000 km, ε = 10%, and κ = 0.05 provide a good fit to the time, range, and frequency dependence of the stacks, although there is a trade‐off between ε and the thickness of the assumed scattering layer. This random media model also fits previously published 1 Hz stacks of P coda and agrees with constraints on long‐wavelength structure from tomography. Finally, we explore geodynamically plausible scenarios that might be responsible for the RMS and falloff rate of the proposed spectrum, including a self‐similar mixture of basalt and harzburgite.
The impact of different aperture distribution models and critical stress criteria on equivalent permeability in fractured rocks
Authors: Bisdom Kevin , Bertotti Giovanni , Nick Hamidreza M. 
Published: May 2016

AbstractPredicting equivalent permeability in fractured reservoirs requires an understanding of the fracture network geometry and apertures. There are different methods for defining aperture, based on outcrop observations (power law scaling), fundamental mechanics (sublinear length‐aperture scaling), and experiments (Barton‐Bandis conductive shearing). Each method predicts heterogeneous apertures, even along single fractures (i.e., intrafracture variations), but most fractured reservoir models imply constant apertures for single fractures. We compare the relative differences in aperture and permeability predicted by three aperture methods, where permeability is modeled in explicit fracture networks with coupled fracture‐matrix flow. Aperture varies along single fractures, and geomechanical relations are used to identify which fractures are critically stressed. The aperture models are applied to real‐world large‐scale fracture networks. (Sub)linear length scaling predicts the largest average aperture and equivalent permeability. Barton‐Bandis aperture is smaller, predicting on average a sixfold increase compared to matrix permeability. Application of critical stress criteria results in a decrease in the fraction of open fractures. For the applied stress conditions, Coulomb predicts that 50% of the network is critically stressed, compared to 80% for Barton‐Bandis peak shear. The impact of the fracture network on equivalent permeability depends on the matrix hydraulic properties, as in a low‐permeable matrix, intrafracture connectivity, i.e., the opening along a single fracture, controls equivalent permeability, whereas for a more permeable matrix, absolute apertures have a larger impact. Quantification of fracture flow regimes using only the ratio of fracture versus matrix permeability is insufficient, as these regimes also depend on aperture variations within fractures.
Multisegment rupture in the 11 July 1889 Chilik earthquake (Mw 8.0–8.3), Kazakh Tien Shan, interpreted from remote sensing, field survey, and paleoseismic trenching
Authors: Abdrakhmatov K. E. , Walker R. T. , Campbell G. E. , Carr A. S. , Elliott A. , Hillemann C. , Hollingsworth J. , Landgraf A. , Mackenzie D. , Mukambayev A. , Rizza M. , Sloan R. A. 
Published: May 2016

AbstractThe 11 July 1889 Chilik earthquake (Mw 8.0–8.3) forms part of a remarkable sequence of large earthquakes in the late nineteenth and early twentieth centuries in the northern Tien Shan. Despite its importance, the source of the 1889 earthquake remains unknown, though the macroseismic epicenter is sited in the Chilik valley, ~100 km southeast of Almaty, Kazakhstan (~2 million population). Several short fault segments that have been inferred to have ruptured in 1889 are too short on their own to account for the estimated magnitude. In this paper we perform detailed surveying and trenching of the ~30 km long Saty fault, one of the previously inferred sources, and find that it was formed in a single earthquake within the last 700 years, involving surface slip of up to 10 m. The scarp‐forming event, likely to be the 1889 earthquake, was the only surface‐rupturing event for at least 5000 years and potentially for much longer. From satellite imagery we extend the mapped length of fresh scarps within the 1889 epicentral zone to a total of ~175 km, which we also suggest as candidate ruptures from the 1889 earthquake. The 175 km of rupture involves conjugate oblique left‐lateral and right‐lateral slip on three separate faults, with step overs of several kilometers between them. All three faults were essentially invisible in the Holocene geomorphology prior to the last slip. The recurrence interval between large earthquakes on any of these faults, and presumably on other faults of the Tien Shan, may be longer than the timescale over which the landscape is reset, providing a challenge for delineating sources of future hazard.
A 530 year long record of the Indian Summer Monsoon from carbonate varves in Maar Lake Twintaung, Myanmar
Authors: Sun Qing , Shan Yabing , Sein Kyaing , Su Youliang , Zhu Qingzen , Wang Luo , Sun Jiming , Gu Zhaoyan , Chu Guoqiang 
Published: May 2016

AbstractWe report an annually laminated sequence spanning the past 530 years from Maar Lake Twintaung, Myanmar. Calcareous varves appear as rhythmic units of light‐colored carbonate and dark‐colored biogenic‐clastic lamina in the sediment. The light‐colored carbonate layers are formed in the dry season due to strong evaporation and Spirulina blooms. The varved sequence provides a high‐resolution geochemical archive of paleoclimatic variability in this tropical, data sparse area. A synchrotron radiation X‐ray fluorescence method was used to analyze elemental data at seasonal to annual time scales. In this arid region, elemental Ca and Sr are mainly regulated by the balance of evaporation and precipitation in this closed lake basin. The elemental variations show distinct interannual and decadal variabilities. On interannual time scales, spectral analysis of the Ca and Sr time series indicates stronger El Niño–Southern Oscillation (ENSO)‐like (Indian Ocean Dipole (IOD)‐like) variability at periods of 2–7 years. It may suggest that ENSO and/or IOD are two dominant modes of regional rainfall variability on interannual time scales over the past 530 years. The quasiperiodicities of approximately 10 years suggest that solar activity may be a critical driving force of monsoonal rainfall in the region. A notable feature is that decreasing monsoonal rainfall since A.D. 1840 is coupled with tropical sea surface temperature variation. Considering that the monsoonal rainfall is coupled with several atmospheric processes evolving at different spatial and temporal scales, more high‐resolution data are required to evaluate and verify the regional rainfall variability and its dynamic links.
Sediment transport through self‐adjusting, bedrock‐walled waterfall plunge pools
Authors: Scheingross Joel S. , Lamb Michael P. 
Published: May 2016

AbstractMany waterfalls have deep plunge pools that are often partially or fully filled with sediment. Sediment fill may control plunge‐pool bedrock erosion rates, partially determine habitat availability for aquatic organisms, and affect sediment routing and debris flow initiation. Currently, there exists no mechanistic model to describe sediment transport through waterfall plunge pools. Here we develop an analytical model to predict steady‐state plunge‐pool depth and sediment‐transport capacity by combining existing jet theory with sediment transport mechanics. Our model predicts plunge‐pool sediment‐transport capacity increases with increasing river discharge, flow velocity, and waterfall drop height and decreases with increasing plunge‐pool depth, radius, and grain size. We tested the model using flume experiments under varying waterfall and plunge‐pool geometries, flow hydraulics, and sediment size. The model and experiments show that through morphodynamic feedbacks, plunge pools aggrade to reach shallower equilibrium pool depths in response to increases in imposed sediment supply. Our theory for steady‐state pool depth matches the experiments with an R2 value of 0.8, with discrepancies likely due to model simplifications of the hydraulics and sediment transport. Analysis of 75 waterfalls suggests that the water depths in natural plunge pools are strongly influenced by upstream sediment supply, and our model provides a mass‐conserving framework to predict sediment and water storage in waterfall plunge pools for sediment routing, habitat assessment, and bedrock erosion modeling.
Active calibration target for bistatic radar cross‐section measurements
Authors: Pienaar M. , Odendaal J. W. , Joubert J. , Cilliers J. E. , Smit J. C. 
Published: May 2016

AbstractEither passive calibration targets are expensive and complex to manufacture or their bistatic radar cross section (RCS) levels are significantly lower than the monostatic RCS levels of targets such as spheres, dihedral, and trihedral corner reflectors. In this paper the performance of an active calibration target with relative high bistatic RCS values is illustrated as a reference target for bistatic RCS measurements. The reference target is simple to manufacture, operates over a wide frequency range, and can be configured to calibrate all four polarizations (VV, HH, HV, and VH). Bistatic RCS measurements of canonical targets, performed in a controlled environment, are calibrated with the reference target and the results are compared to simulated results using FEKO.
Photogrammetric discharge monitoring of small tropical mountain rivers: A case study at Rivière des Pluies, Réunion Island
Authors: Stumpf André , Augereau Emmanuel , Delacourt Christophe , Bonnier Julien 
Published: May 2016

AbstractReliable discharge measurements are indispensable for an effective management of natural water resources and floods. Limitations of classical current meter profiling and stage‐discharge ratings have stimulated the development of more accurate and efficient gauging techniques such as nonintrusive photogrammetric techniques. Despite many successful applications of large‐scale particle image velocimetry (LSPIV) for short‐term measurements during flood events, there are still very few studies that address its use for long‐term monitoring of small mountain rivers. To fill this gap, this study targets the development and testing of largely autonomous photogrammetric discharge measurement system with a special focus on the application to small mountain river with high discharge variability in the tropics. It proposes several enhancements concerning camera calibration, more efficient processing in image geometry, the automatic detection of the water level as well as the statistical calibration and estimation of the discharge from multiple profiles. A case study which comprises the analysis of several thousand videos spanning over 2.5 year is carried out to test the robustness and accuracy of different processing steps. Comparisons against classical current meter profiling show a mean absolute percentage error of 9.0% after the statistical calibration of the system. The study suggests that LSPIV can already be considered as a valuable tool for the monitoring of torrential flows, whereas further research is still needed to fully integrate nighttime observation and stereophotogrammetric capabilities.
An intercomparison of remote sensing river discharge estimation algorithms from measurements of river height, width, and slope
Authors: Durand M. , Gleason C. J. , Garambois P. A. , Bjerklie D. , Smith L. C. , Roux H. , Rodriguez E. , Bates P. D. , Pavelsky T. M. , Monnier J. , Chen X. , Di Baldassarre G. , Fiset J.‐M. , Flipo N. , Frasson R. P. d. M. , Fulton J. , Goutal N. , Hossain F. , Humphries E. , Minear J. T. , Mukolwe M. M. , Neal J. C. , Ricci S. , Sanders B. F. , Schumann G. , Schubert J. E. , Vilmin L. 
Published: May 2016

AbstractThe Surface Water and Ocean Topography (SWOT) satellite mission planned for launch in 2020 will map river elevations and inundated area globally for rivers >100 m wide. In advance of this launch, we here evaluated the possibility of estimating discharge in ungauged rivers using synthetic, daily “remote sensing” measurements derived from hydraulic models corrupted with minimal observational errors. Five discharge algorithms were evaluated, as well as the median of the five, for 19 rivers spanning a range of hydraulic and geomorphic conditions. Reliance upon a priori information, and thus applicability to truly ungauged reaches, varied among algorithms: one algorithm employed only global limits on velocity and depth, while the other algorithms relied on globally available prior estimates of discharge. We found at least one algorithm able to estimate instantaneous discharge to within 35% relative root‐mean‐squared error (RRMSE) on 14/16 nonbraided rivers despite out‐of‐bank flows, multichannel planforms, and backwater effects. Moreover, we found RRMSE was often dominated by bias; the median standard deviation of relative residuals across the 16 nonbraided rivers was only 12.5%. SWOT discharge algorithm progress is therefore encouraging, yet future efforts should consider incorporating ancillary data or multialgorithm synergy to improve results.
Importance of coarse‐mode nitrate produced via sea salt as atmospheric input to East Asian oceans
Authors: Itahashi Syuichi , Hayami Hiroshi , Uno Itsushi , Pan Xiaole , Uematsu Mitsuo 
Published: May 2016

AbstractThe atmospheric input of anthropogenic total reactive oxygenated nitrogen (NOy) to ocean regions in East Asia during 2002–2004 was revisited with an updated regional chemical transport model and the latest emissions inventory. The updated model treats both fine‐ and coarse‐mode nitrate (NO3−). Coarse‐mode NO3− is produced by the reaction of nitric acid (HNO3) and sea salt particles. The modeling system reproduced the atmospheric concentration and wet deposition amount of NO3− quantitatively compared with observations. The fraction of coarse‐mode NO3− was also well captured. NOy deposition amounts over marginal seas and open oceans were 733 and 730 Gg N/yr, which are increases of 1.6‐ and 2.2‐fold, respectively, by including coarse‐mode NO3−. Anthropogenic NOx emissions from China were 5377 Gg N/yr, and 3060 Gg N/yr was exported from China; therefore, the NOy deposition amount over ocean regions in East Asia (1463 Gg N/yr) corresponded to almost half (48%) of the export amounts.
The 2015 Mw 7.1 earthquake on the Charlie‐Gibbs transform fault: Repeating earthquakes and multimodal slip on a slow oceanic transform
Authors: Aderhold K. , Abercrombie R. E. 
Published: May 2016

AbstractThe 2015 Mw 7.1 earthquake on the Charlie‐Gibbs transform fault along the Mid‐Atlantic Ridge is the latest in a series of seven large earthquakes since 1923. We propose that these earthquakes form a pair of quasi‐repeating sequences with the largest magnitudes and longest repeat times for such sequences observed to date. We model teleseismic body waves and find that the 2015 earthquake ruptured a distinct segment of the transform from the previous 1998 earthquake. The two events display similarities to earthquakes in 1974 and 1967, respectively. We observe large oceanic transform earthquakes to exhibit characteristic slip behavior, initiating with small slip near the ridge, and propagating unilaterally to significant slip asperities nearer the center of the transform. These slip distributions combined with apparent segmentation support multimode slip behavior with fault slip accommodated both seismically during large earthquakes and aseismically in between.
The importance of earthquake interactions for injection‐induced seismicity: Retrospective modeling of the Basel Enhanced Geothermal System
Authors: Catalli Flaminia , Rinaldi Antonio P. , Gischig Valentin , Nespoli Massimo , Wiemer Stefan 
Published: May 2016

AbstractWe explore the role of earthquake interactions during an injection‐induced seismic sequence. We propose a model, which considers both a transient pressure and static stress redistribution due to event interactions as triggering mechanisms. By calibrating the model against observations at the Enhanced Geothermal System of Basel, Switzerland, we are able to reproduce the time behavior of the seismicity rate. We observe that considering earthquake interactions in the modeling leads to a larger number of expected seismic events (24% more) if compared to a pressure‐induced seismicity only. The increase of the number of events is particularly evident after the end of the injection. We conclude that implementing a model for estimating the static stress changes due to mutual event interactions increases significantly the understanding of the process and the behavior of induced seismicity.
Impacts of recent climate change on trends in baseflow and stormflow in United States watersheds
Authors: Ficklin Darren L. , Robeson Scott M. , Knouft Jason H. 
Published: May 2016

AbstractCharacterizing the impacts of climatic change on hydrologic processes is critical for managing freshwater systems. Specifically, there is a need to evaluate how the two major components of streamflow, baseflow and stormflow, have responded to recent trends in climate. We derive baseflow and stormflow for 674 sites throughout the United States from 1980 to 2010 to examine their associations with precipitation, potential evapotranspiration, and maximum/minimum temperature. The northeastern (NE) and southwestern (SW) United States display consistent trends in baseflow and stormflow: increasing during fall and winter in the NE and decreasing during all seasons in the SW. Trends elsewhere and at other times of the year are more variable but still associated with changes in climate. Counter to expectations, baseflow and stormflow trends throughout the United States tend to change concurrently. These trends are primarily associated with precipitation trends, but increases in PET are influential and likely to become important in the future.