bluuebunny/crossref_metadata_2025 huggingface dataset:
Bidirectional Volume Exchange Between Kuroshio and East China Sea Shelf Water Based on a Whole‐Region Passive‐Tracing Method
Authors: Hu Fang , Liu Yahao , Xu Zhenhua , Yin Yuqi , Hou Yijun
Published: April 2020

The Kuroshio intrusion has a profound influence on the marine dynamic and ecological environment in the East China Sea (ECS) shelf. In most previous studies, the intrusion has been evaluated by the volume transport across the 200 m isobath. However, this approximate substitution leads to an underestimation of the Kuroshio intruding flux as it fails to separate the onshore and offshore transport of Kuroshio and shelf water. In this paper, a whole‐region passive‐tracing modeling method is proposed to quantitatively explore the bidirectional exchange of Kuroshio and shelf water, by introducing the Kuroshio water concentration as a passive tracer into the flux calculations. In terms of the climatological annual mean, the Kuroshio intrusion onto the ECS shelf is as high as 1.85 Sv (1 Sv = 106 m3 s−1), with a shelf water outflow rate of 0.42 Sv. The real Kuroshio intruding flux is about 30% higher than the net volume transport across the 200 m isobath (1.43 Sv), which indicates that the influence of the Kuroshio intrusion on the ECS may be far greater than believed before. The volume exchange on the inner shelf of the ECS is also discussed. Analyses of the momentum balances indicate that the exchanges on both the shelf break and the inner shelf are generally dominated by the geostrophic balance, but the exchange on the shelf break is more susceptible to nonlinear effects. The results of a set of sensitivity experiments show that variation of the Kuroshio intrusion is mainly regulated by the combined effect of the Kuroshio transport, the Taiwan Strait current, and the local wind stress. In contrast, the local wind stress has a predominant effect on the outflow of shelf water.
Evidence of Eddy‐Enhanced Winter Chlorophyll‐a Blooms in Northern Arabian Sea: 2017 Cruise Expedition
Authors: Wang Tianyu , Du Yan , Liao Xiaomei , Xiang Chenhui
Published: April 2020

The temperature, salinity, and chlorophyll‐a (Chl‐a) profiles of the upper ocean (0–200 m) were measured during the China‐Pakistan Joint Expedition, 2017. The cruise track passed through an identified cyclonic eddy, and the multi‐disciplinary records thus verify the eddy contributions to winter blooms in the northern Arabian Sea (AS). The records show that the strength of upper blooms within the mixed layer is mainly dominated by surface phytoplankton biomass (the Chl‐a concentration), which increases simultaneously with the shallow mixed layer and uplifted thermocline. A composite analysis of eddy‐tracked sea level anomalies (SLA) and Chl‐a reveals the pumping and stirring effects that cyclonic eddies make to the ocean surface nutrient supply. Based on the high‐resolution Ocean General Circulation Model for the Earth Simulator (OFES) outputs, a mixed layer nitrogen budget calculation was subsequently conducted to quantify the contributions of mesoscale eddies to 10‐year climatological winter blooms. The results indicate that eddy flows are primary contributors to the increased nutrients in the coastal north AS during the mature period (usually in January and February) of the winter blooms, with a concentration histogram double that of convective mixing. The concentration decreases from the north to south, agreeing well with the seasonal northward nutrition gradient. This confirms that (i) the growth of nutrients over the northern AS, which is known to be triggered by convective mixing, would be further maintained by eddy‐induced advection; and (ii) higher concentration of nutrients would facilitate an easier response of Chl‐a to eddy dynamics.
Capturing a Mode of Intermediate Water Formation in the Red Sea
Authors: Asfahani Khaled , Krokos George , Papadopoulos Vassilis P. , Jones Burton H. , Sofianos Sarantis , Kheireddine Malika , Hoteit Ibrahim
Published: April 2020

Formation of intermediate waters in the northern Red Sea was captured by Seagliders during the winter of 2016. The analysis is based on measurements collected by consequent deployments of Seaglider autonomous underwater vehicles along a 70 km transect, which was run repeatedly from the coast to midbasin during the period from October 2015 to May 2016. The observations revealed typical open ocean convection processes including a preconditioning phase followed by deep convection and spreading of the newly formed waters through lateral exchange. Winter conditions were characterized by surface cooling and enhanced evaporation, which were observed from late October until late February. During this period, the gradual surface cooling and salinity increase resulted in the weakening of the surface stratification. Recurrent cyclonic gyres forced by strong atmospheric events led to episodic convection and the formation of intermediate seawater typical of the upper overturning circulation cell of the Red Sea. Following deep mixing, a remarkable bloom of chlorophyll was detected at the top layer of the water column in response to the nutrients delivery from the deeper layers. The end of winter was marked by the intrusion of lower salinity water presumably advected from the south and the reestablishment of the general cyclonic circulation, typical for the northernmost part of the Red Sea. To the best of our knowledge, this is the first observation study of such convection events in the northern Red Sea.
Tidal Effect on Water Export Rate in the Eastern Shelf Seas of China
Authors: Lin Lei , Liu Dongyan , Guo Xinyu , Luo Chongxin , Cheng Yao
Published: April 2020

Water export rate of shelf seas is a pivotal factor impacting the global carbon cycle. Tides have important impacts on shelf hydrodynamics but are excluded in many climate models. To assess the effect of tides on export rates of shelf water, this study used a regional hydrodynamic model and a water residence time (WRT) adjoint model and examined model runs with and without tides for the eastern shelf seas of China. The results show that the average WRTs in the Bohai, Yellow, and East China seas were 11.60, 4.95, and 0.39 years, respectively. When tides were excluded, the WRTs decreased by >70% in the Bohai and Yellow seas and by ~10% in the East China Sea, indicating a significant acceleration in the shelf water export due to the absence of tides. The tidal effect has spatial variability associated with the water depth. Sensitivity experiments suggest that the tidal effect on the mean WRT was stronger than the effect of other dynamical factors (winds, rivers, and boundary currents). In the model with tides, tides weakened the wind‐driven coastal current by intensifying the bottom resistance and thus slowed water export in the inner and middle portions of the shelf, compared to the model without tides. Parameterization of the tidal bottom friction in the model without tides could significantly improve the WRT result. This study highlights the crucial role of tides on the long‐term transport of shelf seas and the significance of parameterizing the effect of tidal friction in climate models.
Enhanced Dust Influx to South Atlantic Sector of Antarctica During the Late‐20th Century: Causes and Contribution to Radiative Forcing
Authors: Laluraj C. M. , Rahaman Waliur , Thamban Meloth , Srivastava Rohit
Published: April 2020

Atmospheric dust influences global climate and ocean biogeochemistry. Here we present a high‐resolution ice core dust record (1905–2005 CE) from coastal Dronning Maud Land (71°20′S, 11°35′E), East Antarctica, to understand dust flux variability, its causes, and potential contribution to radiative forcing during the 20th century in the South Atlantic sector of East Antarctica (SASA). The dust flux profile (sum of 1–25 μm size fractions) reveals three stepwise increase during 1905–1929, 1930–1979, and 1980–2005 CE time with an average of 0.83, 4.7, and 12.88 mg·m−2·year−1, respectively. Our investigation for such dramatic dust flux increase reveals that the increased aridity and favorable wind conditions over Southern South America (SSA), a potential dust source to Antarctica, caused increase in dust production and transport during the late 20th century. The dust flux variability in Southern Hemisphere is concomitant with in‐phase relationship between El‐Niño Southern Oscillation and Pacific Decadal Oscillations, which influenced the spatial distribution of global wet‐dry phase (precipitation pattern). Further, shifting of Southern Annular Mode to positive phase made wind conditions more conducive for long‐range dust transport from SSA to coastal Dronning Maud Land region. To the best of our knowledge, this is the first report of past radiative forcing estimates for Antarctica using ice core dust record into a radiative transfer model. Our estimates of radiative forcing corresponding to the enhanced dust flux yield nearly 30% increase in aerosol forcing during the late 20th century. This has resulted 40% decrease in atmospheric cooling rate, which contributed to net atmospheric warming over SASA.
Determining Electric Fields in Thunderclouds With the Radiotelescope LOFAR
Authors: Trinh T. N. G. , Scholten O. , Buitink S. , Ebert U. , Hare B. M. , Krehbiel P. R. , Leijnse H. , Bonardi A. , Corstanje A. , Falcke H. , Huege T. , Hörandel J. R. , Krampah G. K. , Mitra P. , Mulrey K. , Nelles A. , Pandya H. , Rachen J. P. , Rossetto L. , Rutjes C. , ter Veen S. , Winchen T.
Published: April 2020

An analysis is presented of electric fields in thunderclouds using a recently proposed method based on measuring radio emission from extensive air shower events during thunderstorm conditions. This method can be regarded as a tomography of thunderclouds using cosmic rays as probes. The data cover the period from December 2011 till August 2014. We have developed an improved fitting procedure to be able to analyze the data. Our measurements show evidence for the main negative‐charge layer near the −10° isotherm. This we have seen for a winter as well as for a summer cloud where multiple events pass through the same cloud and also the vertical component of the electric field could be reconstructed. On the day of measurement of some cosmic‐ray events showing evidence for strong fields, no lightning activity was detected within 100 km distance. For the winter events, the top heights were between 5 and 6 km, while in the summer, typical top heights of 9 km were seen. Large horizontal components in excess of 70 kV/m of the electric fields are observed in the middle and top layers.
Carbon 13 Isotopes Reveal Limited Ocean Circulation Changes Between Interglacials of the Last 800 ka
Authors: Bouttes N. , Vazquez Riveiros N. , Govin A. , Swingedouw D. , Sanchez‐Goni M. F. , Crosta X. , Roche D. M.
Published: April 2020

Ice core data have shown that atmospheric CO2 concentrations during interglacials were lower before the Mid‐Brunhes Event (MBE, ~430 ka), than after the MBE by around 30 ppm. To explain such a difference, it has been hypothesized that increased bottom water formation around Antarctica or reduced Atlantic Meridional Overturning Circulation (AMOC) could have led to greater oceanic carbon storage before the MBE, resulting in less carbon in the atmosphere. However, only few data on possible changes in interglacial ocean circulation across the MBE have been compiled, hampering model‐data comparison. Here we present a new global compilation of benthic foraminifera carbon isotopic (δ13C) records from 31 marine sediment cores covering the last 800 ka, with the aim of evaluating possible changes of interglacial ocean circulation across the MBE. We show that a small systematic difference between pre‐ and post‐MBE interglacial δ13C is observed. In pre‐MBE interglacials, northern source waters tend to have slightly higher δ13C values and penetrate deeper, which could be linked to an increased northern sourced water formation or a decreased southern sourced water formation. Numerical model simulations tend to support the role of abyssal water formation around Antarctica: Decreased convection there associated with increased sinking of dense water along the continental slopes results in increased δ13C values in the Atlantic in agreement with pre‐MBE interglacial data. It also yields reduced atmospheric CO2 as in pre‐MBE records, despite a smaller simulated amplitude change compared to data, highlighting the need for other processes to explain the MBE transition.
Physical Constraints for Improved Soil Hydraulic Parameter Estimation by Pedotransfer Functions
Authors: Lehmann Peter , Bickel Samuel , Wei Zhongwang , Or Dani
Published: April 2020

Global land surface models use spatially distributed soil information for the parameterization of soil hydraulic properties (SHP). Parameters of measured SHP are correlated with easy‐to‐measure soil properties to construct general pedotransfer functions (PTFs) used to predict SHP from spatial soil information. Global PTFs are based on a limited number of samples yielding highly variable and poorly constrained SHP. The study implements a physical constraint, soil‐specific capillary length, to reduce unphysical combinations of SHP. The procedure fits concurrently soil water retention and capillary length using the same parameters. Results suggest that meeting the capillary length constraint has minor effects on the goodness of fit to soil water retention data. Constrained SHP were applied to represent 4 years of lysimeter fluxes yielding evapotranspiration values in close agreement with measurements relative to slight overestimation by unconstrained SHP. The procedure was applied for testing constraint SHP at a regional scale in New Zealand using the surface evaporation capacitance model and Noah‐MP for detailed simulations of land surface processes. The use of constrained SHP in both models yields higher surface runoff in agreement with observations (unconstrained SHP severely underestimated runoff generation). The concept of constrained SHP could be extended to include other physical constraints to improve PTFs, for example, by consideration of vegetation cover and soil structure effects on infiltration.
Physics‐Informed Deep Neural Networks for Learning Parameters and Constitutive Relationships in Subsurface Flow Problems
Authors: Tartakovsky A. M. , Marrero C. Ortiz , Perdikaris Paris , Tartakovsky G. D. , Barajas‐Solano D.
Published: April 2020

We present a physics‐informed deep neural network (DNN) method for estimating hydraulic conductivity in saturated and unsaturated flows governed by Darcy's law. For saturated flow, we approximate hydraulic conductivity and head with two DNNs and use Darcy's law in addition to measurements of hydraulic conductivity and head to train these DNNs. For unsaturated flow, we approximate unsaturated conductivity function and capillary pressure with DNNs and train these DNNs using measurements of capillary pressure and the Richards equation. Because it is difficult to measure unsaturated conductivity in the field, we assume that no measurements of unsaturated conductivity are available. The proposed approach enforces the partial differential equation (PDE) (Darcy or Richards equation) constraints by minimizing the PDE residual at select points in the simulation domain. We demonstrate that physics constraints increase the accuracy of DNN approximations of sparsely observed functions and allow for training DNNs when no direct measurements of the functions of interest are available. For the saturated conductivity estimation problem, we show that the physics‐informed DNN method is more accurate than the state‐of‐the‐art maximum a posteriori probability method. For the unsaturated flow in homogeneous porous media, we find that the proposed method can accurately estimate the pressure‐conductivity relationship based on the capillary pressure measurements only, even in the presence of measurement noise.
A Technical Evaluation of Lidar‐Based Measurement of River Water Levels
Authors: Paul Jonathan D. , Buytaert Wouter , Sah Neeraj
Published: April 2020

Measuring river water level (stage) is key for a variety of applications including discharge estimation and flood prediction. Although a variety of in situ and noncontact methods are available, there is an urgent need for new and more cost‐efficient methods. Rapid technological progress has accelerated the use of noncontact methods and development of time‐of‐flight distance sensors. Among available techniques, the use of lidar for distance measurement is promising because of its low cost, high energy efficiency, and small measurement footprint. However, lidar has rarely been used to measure water levels. Here we test a near‐infrared (905 nm) lidar sensor to determine its suitability for stage measurements under a range of environmental conditions. Using different laboratory and field setups, we assess sensor performance as a function of measurement distance, surface roughness, air temperature, water turbidity, and measurement angle. Despite the low reflectivity of water for infrared radiation, we find that the tested sensor is able to take measurements under all tested conditions, up to an incidence angle of ∼40°. The accuracy of the sensor is within the technical specifications of the device and is characterized by a relative error of around 0.1%. We find a strong dependence of the accuracy on sensor temperature, which we attribute to suboptimal internal compensation of the electronics. The precision of the sensor decreases with increasing measured distance and increases with surface roughness of the water body. We did not find any significant impact of water turbidity on the measurements.
An Automatic Framework of Region‐of‐Interest Detection and Classification for Networked X‐Band Weather Radar System
Authors: Xu Zi‐Xin , Yang Ling , Lei Bo , Li Xuehua , Zhen Xiaoqiong
Published: April 2020

Nowadays, S‐band weather radars are designed to observe weather conditions within large area. However, S‐band radars suffer from large blind zone at low elevation and fixed scan strategy so that they are not efficient for surveillance of convective weathers such as tornado. Networked X‐band weather radars are thereby proposed to overcome this issue. One key problem of networked radar is to automatically determine the type and the precise position of convective cells that are worthwhile to detect. In this paper, a tailor‐made framework is proposed to automatically find the convective cells and retrieve information of them from reflectivity product of networked X‐band weather radars. The framework consists of three substeps: convection pixel retrieval by Back Propagation Neural Network (BPNN), convection cell construction by Density‐Based Spatial Clustering of Applications with Noise (DBSCAN), and convection cell classification by Convolutional Neural Network (CNN). Evaluation results show that the proposed algorithm is capable to identify isolated single‐cell and multicell convective storms from the reflectivity image accurately. Therefore, the proposed framework is capable to provide information for networked X‐band weather radars so that they can track harmful convective weathers. The proposed framework has been embedded in the meteorological command and control (MCC) center of networked X‐band radar system in Chengdu.
Keppel-Aleks, Swann, and Xu Receive 2019 Global Environmental Change Early Career Award
Authors:   AGU
Published: April 2020

Gretchen Keppel-Aleks, Abigail L. S. Swann, and Yangyang Xu received the Global Environmental Change Early Career Award at AGU’s Fall Meeting 2019, held 9–13 December in San Francisco, Calif. The award recognizes an early-career scientist “for outstanding contributions in research, educational, or societal impacts in the area of global environmental change,” especially through an interdisciplinary approach.
Ductility and Compressibility Accommodate High Magma Flux Beneath a Silicic Continental Rift Caldera: Insights From Corbetti Caldera (Ethiopia)
Authors: Gottsmann J. , Biggs J. , Lloyd R. , Biranhu Y. , Lewi E.
Published: April 2020

Large silicic magma reservoirs preferentially form in the upper crust of extensional continental environments. However, our quantitative understanding of the link between mantle magmatism, silicic reservoirs, and surface deformation during rifting is very limited. Here, we focus on Corbetti, a peralkaline caldera in the densely populated Main Ethiopian Rift, which lies above a focused zone of upper mantle partial melt and has been steadily uplifting at a maximum rate of 6.6±1.2 cm yr−1 for more than 10 yr. Numerical modeling shows that a maximum concomitant residual gravity increase of 9±3 μGal yr−1 by the intrusion of mafic magma at ∼7 km depth into a compressible and inelastic crystal mush best explains the observed deformation and gravity changes. The derived magma mass flux of ∼1011 kg yr−1 is anomalously high and at least 1 order of magnitude greater than the mean long‐term mass eruption rate. This study demonstrates that periodic and high‐rate magmatic rejuvenation of upper‐crustal mush is a significant and rapid contributor to mature continental rifting.
Magnetospheric Multiscale (MMS) Observations of Magnetic Reconnection in Foreshock Transients
Authors: Liu Terry Z. , Lu San , Turner Drew L. , Gingell Imogen , Angelopoulos Vassilis , Zhang Hui , Artemyev Anton , Burch James L.
Published: April 2020

Magnetic reconnection is a fundamental process of energy conversion in plasmas between electromagnetic fields and particles. Magnetic reconnection has been observed directly in a variety of plasmas in the solar wind and Earth's magnetosphere. Most recently, electron magnetic reconnection without ion coupling was observed for the first time in the turbulent magnetosheath and within the transition region of Earth's bow shock. In the ion foreshock upstream of Earth's bow shock, there may also be magnetic reconnection especially around foreshock transients that are very turbulent and dynamic. With observations from the National Aeronautics and Space Administration's Magnetospheric Multiscale mission inside foreshock transients, we report two events of magnetic reconnection with and without a strong guide field, respectively. In both events, a super‐ion‐Alfvénic electron jet was observed within a current sheet with thickness less than or comparable to one ion inertial length. In both events, energy was converted from the magnetic field to electrons, manifested as an increase in electron temperature. Weak or no ion coupling was observed in either event. Results from particle‐in‐cell simulations of magnetic reconnection with and without a strong guide field are qualitatively consistent with observations. Our results imply that magnetic reconnection is another electron acceleration/heating process inside foreshock transients and could play an important role in shock dynamics.
New Observations of Large‐Scale Waves Coupling With the Ionosphere Made by the GOLD Mission: Quasi‐16‐Day Wave Signatures in the F‐Region OI 135.6‐nm Nightglow During Sudden Stratospheric Warmings
Authors: Gan Quan , Eastes Richard W. , Burns Alan G. , Wang Wenbin , Qian Liying , Solomon Stanley C. , Codrescu Mihail V. , McClintock William E.
Published: April 2020

The recently launched Global‐scale Observations of the Limb and Disk (GOLD) Mission observed prominent quasi‐16‐day oscillations (Q16DOs) in the OI 135.6‐nm nightglow from the equatorial ionization anomaly (EIA) region during 26 November 2018 to 25 January 2019. Meanwhile, the enhanced and concurrent quasi‐16‐day wave (Q16DW) activity was observed in the middle atmosphere by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument. This implies that the F‐region ionosphere couples with the lower atmosphere through large‐scale waves. A noteworthy phenomenon was that the Q16DOs displayed an asymmetric behavior between the northern and southern EIA crests. This asymmetry indicates that the ionospheric Q16DOs might be driven by the Q16DW‐modulated tides, which not only modulated the E‐region dynamo winds but also modulated the F‐region field‐aligned neutral winds via vertical penetration, producing the oscillations in plasmas densities.
Numerical Investigation of Baroclinic Channel‐Shoal Interaction in Partially Stratified Estuaries
Authors: Zhou Jian , Stacey Mark T. , Holleman Rusty C. , Nuss Emma , Senn David B.
Published: April 2020

The internal, density‐driven channel‐shoal interaction in partially stratified estuaries is numerically investigated. Idealized General Estuarine Transport Model (GETM) simulations with the rigid‐lid assumption are performed in a two‐dimensional cross‐sectional mode forced by a constant longitudinal salinity gradient and an M2 tidal current. Simulation results show that within each tide cycle, the abrupt flattening of bathymetry at the channel‐shoal interface leads to the trapping of a patch of high‐salinity water mass on the shoal. The resulting local salinity maximum near the interface interacts with the differential advection by the gentle slope of shoal, driving complex density‐driven on‐shoal lateral circulations. Next, it is found that the presence of the shoal in turn enhances the longitudinal residual circulation in the channel. As a storage of estuarine water that is partially isolated from the main stream, the shoal traps saltier water that originates from the channel during slack after ebb (thus a less stratified flood), while injects fresher water into the surface of the channel during slack after flood (thus a more stratified ebb). These lateral baroclinic exchanges across the channel‐shoal interface give rise to a new mechanism for generating tidal asymmetry of eddy viscosity and shear in the channel (i.e., tidal straining circulation), which has the same orientation with the classical estuarine circulation. The interfacial salt trapping and the accompanied shoal‐induced modification of channel residual circulation are demonstrated to possess a highly localized nature, with their characteristics largely independent of shoal bathymetry far away from the channel‐shoal interface.
Biomarker Fingerprint of Debris Flow Deposits as a Paleoproxy for IRD Sources in the Last Glacial North Atlantic
Authors: Wary Mélanie , Kornilova Oksana , Russell Marie , Rosell‐Melé Antoni
Published: April 2020

Investigating the spatiotemporal dynamics of iceberg discharges during the last glacial period constitutes a major challenge for paleoclimate research. In recent decades, many ice‐rafted debris (IRD) provenance studies, mostly based on the comparison of the inorganic signature of IRD‐rich layers and surrounding continental bedrock, have differentiated main subareas of individual ice sheets as iceberg sources and gauged their dynamic interplay. Diagnosis of specific source ice streams has nonetheless remained limited. Here we propose a new IRD provenance methodology to refine the identification of iceberg sources. It relies on the organic geochemical characterization of glacigenic debris flow (GDF) deposits to obtain the biomarker fingerprint of IRD sources. To test its potential, we analyze the composition of n‐alkanes and chlorophyll‐derived pigments in sediments deposited within six major North Atlantic GDF depocenters fed by ice streams draining the surrounding ice sheets. The biomarker fingerprint of GDF deposits appears to (1) be consistent with a common origin of IRD and GDF deposits through erosion of outcrops and transport by ice streams, (2) differ significantly from that of ambient hemipelagic sediments, (3) be specific and unique to each GDF depocenter, making it possible to distinguish the corresponding specific ice streams, (4) be imprinted in IRD‐bearing marine sediments, and (5) have remained homogeneous enough through the last glacial to be used as a proxy for IRD sources. The biomarker fingerprint of GDF deposits thus shows strong potential to track the specific source ice streams that delivered IRD to the last glacial North Atlantic.
Homogeneous multiplexed digital detection of microRNA with ligation-rolling circle amplification
Authors: Hu Zhian , Xu Fujian , Sun Gongwei , Zhang Sichun , Zhang Xinrong
Published: April 2020

MicroRNA was transformed into a DNA nanoflower ball by LRCA reaction for homogeneous multiplexed digital detection using flow cytometry.
Motional freedom of dimethylammonium ions in a cyanoelpasolite, [(CH3)2NH2]2KCo(CN)6, which exhibits phase transition associated with a distinct change in dielectric property
Authors: Asaji Tetsuo
Published: April 2020

Although the phase transition of (DMA)2KCo(CN)6 has been reported as an isosymmetric transition, 14N NQR spectra showed a lowering of crystal symmetry.
Ta3N5-Nanorods enabling highly efficient water oxidation via advantageous light harvesting and charge collection
Authors: Pihosh Yuriy , Minegishi Tsutomu , Nandal Vikas , Higashi Tomohiro , Katayama Masao , Yamada Taro , Sasaki Yutaka , Seki Kazuhiko , Suzuki Yohichi , Nakabayashi Mamiko , Sugiyama Masakazu , Domen Kazunari
Published: April 2020

Well-aligned polycrystalline Ta3N5-NRs provide enhanced light harvesting and efficient generation and extraction of charge carriers, leading to completely saturated photocurrent.
Application of temperature-controlled chiral hybrid structures constructed from copper(ii)-monosubstituted Keggin polyoxoanions and copper(ii)-organoamine complexes in enantioselective sensing of tartaric acid
Authors: Yang Mu-Xiu , Zhou Meng-Jie , Cao Jia-Peng , Han Ye-Min , Hong Ya-Lin , Xu Yan
Published: April 2020

A pair of temperature-controlled chiral compounds,d-andl-[Cu(en)2(H2O)]2{[Cu(en)(H2O)2][SiCuW11O39]}·5H2O (en = ethanediamine) are isolated by hydrothermal method, having a good application prospect in sensingd-/l-tartaric acid.
Blue-green-emitting cationic iridium complexes with oxadiazole-type counter-anions and their use for highly efficient solution-processed organic light-emitting diodes
Authors: Meng Xianwen , Wang Pei , Bai Rubing , He Lei
Published: April 2020

Cationic iridium complexes with 2,5-diphenyl-1,3,4-oxadiazole type counter-anions afford highly-efficient solution-processed blue-green organic light-emitting diodes.
Extraction of respiratory rate from PPG using ensemble empirical mode decomposition with Kalman filter
Authors: Sharma H.
Published: April 2020

This Letter suggests a simple but effective approach for accurate estimation of respiratory rate (RR) from the photoplethysmogram (PPG). In the suggested technique, the PPG signal is first decomposed into a number of intrinsic mode functions (IMFs) using the ensemble empirical mode decomposition (EEMD). The IMFs comprising respiratory information are selected and used to reconstruct the signal. A Kalman filter coupled with the signal quality measure of PPG is utilised to process the reconstructed signal to derive the respiratory signal for RR estimation. Experiments are conducted on two independent datasets, namely CapnoBase and MIMIC. Based on experimental results, the technique is found to be outperforming the existing methods by achieving lower error in the estimated RRs on both datasets. This work demonstrates the potential of the EEMD method with Kalman filter for precise estimation of RR from PPG to contribute to the advancement of portable healthcare systems with a fewer number of sensors.
Improved LDMOS‐SCR for high‐voltage electrostatic discharge (ESD) protection applications
Authors: Song Wenqiang , Hou Fei , Du Feibo , Liu Jizhi , Liu Zhiwei , Liou Juin J.
Published: April 2020

An improved lateral double‐diffused MOS silicon‐controlled rectifier (ILDMOS‐SCR) for high‐voltage electrostatic discharge (ESD) protection applications has been proposed and verified in a 0.18 µm 5 V/24 V BCD process. The proposed improved lateral double‐diffused MOS silicon‐controlled rectifier (LDMOS‐SCR) is constructed by adding a gated P‐type/intrinsic/N‐type (PIN) diode into a conventional LDMOS‐SCR. With part of the ESD current discharges from the surface gated PIN diode path, the proposed ILDMOS‐SCR achieves a high holding voltage of 30 V as well as a high failure current of 10.04 A, which is evaluated to pass 15 KV Human Body Model (HBM) ESD stress.
Motion boundary emphasised optical flow method for human action recognition
Authors: Peng Cheng , Huang Haozhi , Tsoi Ah‐Chung , Lo Sio‐Long , Liu Yun , Yang Zi‐yi
Published: April 2020

This study proposes a three‐stream model using two different types of deep convolutional neural networks (CNNs): (i) a spatial stream with a CNN on images; (ii) a ResNet (residual network) on optical flows; and, (iii) a ResNet on the concatenation of motion features. This model is applied to four datasets: (i) UCF Sports; (ii) Youtube Sports; (iii) SBU action interaction; and (iv) a subset of the UCF‐1M Sports. Using two optical flow estimation methods: (i) a motion boundary emphasised Epicflow (Edge Preserving Interpolation Correspondences for Optical Flow) method, (MBEpicflow); and (ii) the Flownet 2 method, a learning optical flow estimation method. It was found that (i) the proposed MBEpicflow outperforms the Flownet 2 method on the SBU dataset, while the Flownet 2 performs equally well or better than the MBEpicflow method on the other three datasets, and these results are the best when compared with those obtained using other approaches on all datasets evaluated. These results showed the importance of accurate optical flow plays in human action recognition, an aspect which has been seldom addressed. Moreover, it showed that if some measure of the global behaviours of motion is incorporated, the generalisation performance is often improved by 1–2%.
Accurate and fast single shot multibox detector
Authors: Guo Lie , Wang Dongxing , Li Linhui , Feng Jindun
Published: April 2020

With the development of deep learning, the performance of object detection has made great progress. However, there are still some challenging problems, such as the detection accuracy of small objects and the efficiency of the detector. This study proposes an accurate and fast single shot multibox detector, which includes context comprehensive enhancement (CCE) module and feature enhancement module (FEM). To integrate more efficient information when aggregating context information, the conv4_3 and fc_7 feature maps are merged to design the CCE module. To obtain more fine‐grained feature information, this study presents a FEM and special feature enhancement module (FEM‐s) module that can fuse different receptive field sizes to better adapt to the scale change of the object. Compared to existing methods based on deep learning, the proposed method helps to gradually produce more detailed feature maps with better performance. Under the premise of ensuring real‐time speed, the authors network can achieve 81.2 mean average precision on the PASCAL VOC 2007 test with an input size of 320 × 320 on a single Nvidia 2080Ti GPU.
Inference robust to outliers with ℓ1-norm penalization
Authors: Beyhum Jad
Published: April 2020

This paper considers inference in a linear regression model with outliers in which the number of outliers can grow with sample size while their proportion goes to 0. We propose a square-root lasso ℓ1-norm penalized estimator. We derive rates of convergence and establish asymptotic normality. Our estimator has the same asymptotic variance as the OLS estimator in the standard linear model. This enables us to build tests and confidence sets in the usual and simple manner. The proposed procedure is also computationally advantageous, it amounts to solving a convex optimization program. Overall, the suggested approach offers a practical robust alternative to the ordinary least squares estimator.
Dynamic vs. static maintenance rate policies for multi-state queueing systems
Authors: Chen Gang , Liu Zaiming , Chu Yuqing
Published: April 2020

This paper considers a single-server queueing system with server breakdowns. When the server fails, it is sent to repair immediately and its maintenance rate is allowed to be adjustable. The goal is to find the optimal maintenance rates that minimize the long-run average cost of the system. We address the static and dynamic maintenance control problems respectively. For the static control model, we derive the stationary system performances and the explicit solution of the optimal maintenance rate. Then regarding the dynamic maintenance problem, we formulate it as a Markov decision process (MDP) and the optimal dynamic policy is proved to be a threshold policy. Based on the structure of optimal dynamic policy, we construct a performance evaluation for computing efficiently the optimal threshold and average cost. Finally, a comparative study of the dynamic and static policies is presented by numerical experiment which shows the impact of system parameters on the optimal maintenance policies.
Use of Graph Based Descriptors for Determination of Structural Features Causing Modulation of Fructose-1,6-Bisphosphatase
Authors: Kumar Ashwani , Bagri Kiran , Kumar Parvin ,   Manisha
Published: April 2020

Fructose-1,6-bisphosphatase performs a significant function in regulating the blood glucose level in type 2 diabetes by controlling the process gluconeogenesis. In this research work optimal descriptor (graph) based quantitative structural activity relationship studies of a set of 203 fructose-1,6-bisphosphatase has been performed with the help of Monte Carlo optimization. Distribution of compounds into different sets such as training set, invisible training set, calibration set and validation sets resulted in formation of splits. Statistical parameters obtained from quantitative structural activity relationship modeling were good for various designed splits. The statistical parameters such as R2 and Q2 for calibration and validation sets of best split developed were found to be 0.8338, 0.7908 & 0.7920 and 0.7036 respectively. Based on the results obtained for correlation weights, different structural attributes were described as promoters and demoters of the endpoint. Further these structural attributes were used in designing of new fructose-1,6-bisphosphatase inhibitors and molecular docking study was accomplished for the determination of interactions of designed molecules with the enzyme.
Epileptic Spasms in an Infant with Incontinentia Pigmenti: Report of a Rare Case with Brief Review of the Literature
Authors: Sharawat Indar Kumar , Panda Prateek Kumar
Published: April 2020

Incontinentia pigmenti (IP) or Bloch–Sulzberger’s disease is a rare neurocutaneous syndrome with dermatological, neurologic, and systemic manifestations including retinal, dental and hair abnormalities. It follows X-linked dominant inheritance and predominantly affects female children. The characteristic evolution of skin lesions in four stages is a hallmark diagnostic feature of the disease. The pigmented lesions of IP are usually distributed in linear streaks, macular whorls, reticulated patches, and flecks along the Blaschko lines. Neurologic morbidities are found in a considerable proportion of affected children, and the spectrum includes seizures, neuromotor impairment, microcephaly, developmental delay, and intellectual disability. Seizures are reported in 10% to 25% of children with IP in various previous clinical studies. The majority of these children had seizures in the neonatal period or early infancy, and focal–clonic seizure is the commonest observed semiology. However, there are only a few case reports of infants with IP with epileptic spasms. In this report, the clinical course of a 6-month-old girl with IP and epileptic spasms has been described, who responded favorably to treatment with adrenocorticotropic hormone injection. Clinicians managing children with IP should be aware of their predisposition to develop epileptic spasms and consider neuroimaging, electroencephalogram, and other investigations accordingly.
Thermoelasticplastic deformation of a functionally graded spherical layer
Authors: Akinlabi E. T. , Dats E. P. , Murashkin E. V.
Published: April 2020

The paper deals with the problem of calculation of residual stresses and displacements in functionally graded material under thermal treatment. The investigated multilayered object has a spherical form. The model of thermoelastic plastic deformation is used. The method of construction of analytical solution is proposed and discussed. The distributions of stresses and displacements in the one-dimensional problem of heating a multilayer sphere are obtained and graphically analysed.
Experimental and theoretical studies of the effect of long-term natural aging on the mechanical properties of high impact polystyrene
Authors: Arutyunyan A R
Published: April 2020

Effect of prolonged natural aging in the laboratory conditions at room temperature during 40 years on the mechanical properties of six different marks of high impact polystyrene (HIPS) was investigated. The deformation curves in tensile experiments were obtained. These curves indicated that the hardening effect is observed for all marks of HIPS after aging. The HIPS were also tested for creep at room temperature and constant tensile force. Specimens of most marks of HIPS does not fractured during 30 days. After natural aging during 40 years, the specimens were fractured in a time-to-fracture range from 10 minutes to 30 hours depending on the mark of HIPS. A modified version of the Maxwell equation written in the effective time scale is used to describe the obtained experimental creep curves. A good agreement between theoretical and experimental creep curves is observed.
Deformability during short-term loading, shrinkage and creep of a cementitious soil composite on the basis of belozems of carbonate
Authors: Karapetyan K A , Hairoyan S H , Manukyan E S
Published: April 2020

The results of short-term (strength, tangent modulus and transversal deformation coefficient) and long-term (shrinkage and creepage deformations) experimental research of cylindrical test pieces manufactured from the cementitious soil of carbonate composition are considered. The obtained experimental data are compared with similar data defined for the light-weight concrete based on lithoid-pumice.
Numerical analytic method for solving the inverse coefficient problem of heat conduction in anisotropic half-space
Authors: Kolesnik S A , Bulychev N A
Published: April 2020

The paper proposes a numerical-analytical method for solving the inverse problem of identification of the components of the thermal conductivity tensor in anisotropic materials on the basis of the earlier analytical solution of the heat conduction problem in anisotropic half-space when heated with a thermal flow. The method is based upon expansion of the residual functional into Taylor series and determination of incremental vectors of the target coefficients which are then used for application of iterative gradient descent algorithms. The solution demonstrates fine iteration convergence even if the initial approximation of the coefficients vector differs from the target one by several times, and even when there is some inaccuracy in the experimental data. The proposed method can be used for a wide range of problems in continuum mechanics.
On the classification of boundary value problems for elastic homogeneous and piecewise homogeneous spaces with a penny-shaped crack
Authors: Mkhitaryan S M , Mkrtchyan M S , Kanetsyan E G
Published: April 2020

The classification of the basic axisymmetric boundary value problems of the mathematical theory of elasticity for homogeneous and piecewise homogeneous elastic spaces with a penny-shaped crack is given. Using the Hankel integral transform, governing integral equations (GIEs) of these problems are derived and methods for finding their exact solutions are indicated.
Pressure calculation using obstacle problem for CMP modeling
Authors: Piliposyan D , Ghulghazaryan R , Poghosyan M , Nersisyan H
Published: April 2020

Chemical mechanical polishing/planarization (CMP) is one of the most important fabrication technologies in the semiconductor industry. CMP is used to achieve planar surfaces and remove excess deposited material from the wafer. During CMP, a chemical “slurry” containing abrasive particles and chemical reagents is deposited on the polishing pad. The polishing pad is then pressed against the rotating wafer. The combined action of the polishing pad and chemical slurry results in material removal and planarization of the wafer surface. Modeling of the CMP process allows detection of potential planarization defects in chips before manufacturing. Accurate computation of pressure distribution across the wafer surface is crucial for accurate modeling of the CMP process. The pressure distribution calculation is usually done using the Hertz contact theory and Chekina model, which involves computations of direct and inverse fast Fourier transforms (FFT and IFFT) and pad displacements updates. In this paper, we adopted an obstacle problem approach for calculating the pressure distribution across the wafer/die surface for CMP modeling. In an obstacle problem, the pad is assumed to be an elastic membrane with fixed boundaries that is displaced by the wafer surface. The goal is to find the equilibrium position for the pad and calculate the pressure distribution over the surface in contact. The main advantage of this approach is that computations of FFT and IFFT and recalculations of the pad displacements can be avoided. This can lead to a more accurate model that is independent of pad displacement update method. The approach is tested on several examples. The results show correct physical behaviour and are in agreement with expectations.
The uni-axial tensile response of titanium-based fiber metal laminates
Authors: Sharma A P , Velmurugan R
Published: April 2020

Fiber metal laminates (FMLs) consist of thin layers of metal bonded together with layers of composite based on fiber reinforcement. In the present study, titanium sheets (Ti-6Al-4V) having thicknesses of 0.2 mm, 0.4 mm, and 0.6 mm and glass-fiber reinforced composite layers having uni-directional layup are considered to fabricate FMLs and response of these laminates are evaluated under tension. The consideration for four discrete sequences of stacks is made for FMLs preserving thickness of a total layer of metal same and these laminates are fabricated using a method of hand layup. The elastic modulus, yield strength and ultimate strength of FMLs are theoretically predicted by rule of mixtures (ROM). The layup’s sequence does not affect initial modulus of FMLs subjected to tension. Whereas, the ultimate strength and FMLs’ behavior succeeding ultimate strength are significantly affected by layup’s sequence. The properties of a laminate obtained from experiment and predicted from ROM are found in good agreement with each other.
Vibration isolation of rolling bearings in electric machines
Authors: Shekyan H G , Gevorgyan A V
Published: April 2020

In the paper forced vibrations of high-speed electric machines with rotors on the rolling bearings are considered. It is shown that in high-speed rotor machines the vibration loadings, which bring to overstrain of contact surfaces of the rolling and violation of the bearings work regime, are one of the main reasons of the bearings failure.
A comparative analysis of wave properties of the finite and infinite doubly periodic arrays of volumetric and thin defects
Authors: Sumbatyan M A , Remizov M Yu
Published: April 2020

A two-dimensional problem on wave propagation through doubly periodic arrays of defects located in an elastic material is studied. The incident wave is longitudinal and the defects may be thin (cracks) or volumetric (voids). For both the types of defects the main aim is to compare the wave properties of the structure whose geometry may be either finite or infinite in the transversal periodic direction with respect to the direction of the incident wave. The physical parameters under consideration are the reflection and the transmission coefficients, which are studied versus frequency parameter in the one-mode regime.