bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Needle Diameter on Optical Properties and Morphological Structure of La2O3- PVA Phosphor Nanofibers Prepared by Electrospinning Method
Authors: Wahab Hasma A. , Hassan Zainuriah , Ahmed Naser Mahmoud
Published: March 2020

Lanthanum Oxide-Polyvinyl alcohol (La2O3-PVA) phosphor nanofibers were prepared by electrospinning and investigation of the effect of needle diameter on the optical properties and morphological structure at the nanofibers was carried out. The average diameter of phosphor nanofibers have been evaluated for five different needle diameters. The resulting phosphor nanofibers were observed and anaylzed by X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Ultraviolet-visible Spectroscopy (UV-Vis) and HPC-2 Lightsource Colorimeter. The La2O3-PVA phosphor nanofibers were used in light down-conversion of UV light (365 nm) for the white light-emitting diode (WLED) application. The chromaticity coordinates (CIE) and correlated colour temperature (CCT) were measured for different phosphor nanofibers with different sizes of needle diameter (0.45,0.55,0.65,0.75,1.1) mm. The results revealed that the phosphor nanofibers formed by needle diameter of 0.65 mm places macromolecule in a better order and the average diameter increase from 40.08 nm to 87.27 nm after annealing followed by increasing in atomic percentage of lanthanum. The energy gap of resulting phosphor nanofibers is 3.5365 eV. An optimum colour rendering index (CRI) value of 70.20 is obtained. The white phosphor exhibited CIE values of 0.3536, 0.407 and CCT of 4890 K.
Morphological, Structural and Optical Characteristics of Porous GaN Fabricated by UV-Assisted Electrochemical Etching
Authors: Mohd Razali Nurul Syuhadah , Abd Rahim Alhan Farhanah , Radzali Rosfariza , Mahmood Ainorkhilah , Bahrol Anuar Muhammad Faiz
Published: March 2020

The fabrication of porous GaN (PGaN) by UV-assisted electrochemical etching with a variations of current densities (40, 60, and 80 mA/cm2) for 60 min in electrolytes consisting of 4% KOH are reported. Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-Ray (EDX), Atomic Force Microscopy (AFM) and X-ray Diffraction (XRD) were used to characterize the morphological and structural characteristics of the PGaN. All PGaN sample prepared by electrochemical etching technique produced a hexagonal-like pore shape. FESEM images demonstrated that the pore uniformity and porosity are affected significantly by the current density. The PGaN sample fabricated with 80 mA/cm2 produces a uniform and high porosity structure compared to other PGaN sample. This shows that the morphology and structural characteristic of PGaN are increase with the increase of current density. The EDX result revealed significant Ga and N atom presence in all samples. However, the O atom only presence in sample etched with 80 mA/cm2 implying that the etching process is occur vigorously in this sample. The AFM verified that the surface roughness and the pore depth are increased as current density increased. There were relatively large variations of the peak intensities for 2Theta-scan patterns as exposed by XRD. The peak shift for PGaN sample relative to as-grown was inconsistent and the changed was relatively small. Raman intensity found to be enhanced with the increase in current density and among the PGaN sample, the E2(high) peak for sample prepared with 60mA/cm2 and 80mA/cm2 was observed to be slightly shifted to lower frequency. The PL spectra displayed that the porosity has high impact on the PL peak intensity. . Overall, this proved that with the usage of low power UV light, the pore structure still can be produced as good as pore structure fabricated with high power UV light.
Study of the Effect of Injection Currents on White Light Emission of Ce-Doped YAG Phosphor Powder Prepared by Microwave Combustion
Authors: Abd Husnen R. , Hassan Zainuriah , Ahmed Naser Mahmoud , Omar A.F. , Lau Khai Shenn , Alsultany Forat Hamzah
Published: March 2020

The behaviors of yttrium aluminum garnet (YAG) phosphor powder doped by cerium (YAG:Ce3+) was studied. Here, the YAG:Ce3+ nanopowders have been synthesized using microwave combustion (MW) according to the formula, Y(3-0.04) Al5O12: 0.04Ce3+ to produce white light emitting diode (WLEDs) by conversion from blue indium gallium nitride light emitting diode (InGaN LED, 445 nm) chips; the whole process took only 20 min. Pure YAG phase was obtained after annealing at 1050 °C for 5 h with nonaggregated and spherical particles. Thermogravimetry and derivative thermogravimetry (TG/DTG), X-ray powder diffraction (XRPD), transmission electron microscope (TEM), photoluminescence (PL), electroluminescence (EL) emissions and standard CIE 1931 chromaticity diagrams have been used to characterize the samples. The highest WLEDs emission was achieved for the annealed YAG:Ce3+, together with proper color rendering index (CRI), and tunable correlated color temperature (CCT). Finally, we conclude that the decreasing EL intensity at increased injection current is caused by the thermal ionization from the 5d1 level to the conduction band.
Synthesis and Characterization of YAG:Ce Phosphor by Microwave Induced Combustion Synthesis with Different Fuel Sources
Authors: Lau Khai Shenn , Hassan Zainuriah , Lim Way Foong , Quah Hock Jin , Ahmed Naser Mahmoud , Abd Husnen R.
Published: March 2020

White LEDs (WLEDs) have been produced from the combination of blue LED chips and phosphor converter. In the present work, considerable amount of yttrium aluminium garnet (YAG) phosphor powders doped with 0.3 mol% of cerium (Ce) have been synthesized via Microwave Induced Combustion Synthesis (MICS) method with different fuel sources such as urea and mixed fuel of urea and glycine. The effects of different fuel sources on the crystallinity, structure, luminescent properties and Commision International de L’Eclairage (CIE) chromaticity was characterized and studied using high resolution X-ray diffraction (HR XRD), field emission-scanning electron microscopy (FE SEM), energy dispersive X-ray spectroscopy (EDX), electroluminescence (EL) and standard CIE 1931 chromaticity diagram, respectively. The highest EL intensity can be observed from the sample prepared by mixed fuel technique. In contrast, the experimental enhancement in the aforementioned properties was demonstrated by the WLED synthesized using mixed fuel technique. Keywords: White LEDs, phosphor converter, microwave induced combustion, mixed fuel technique.
T Cell Cytokines Impact Epithelial Cell Responses during Helicobacter pylori Infection
Authors: Algood Holly M. Scott
Published: March 2020

The goal of this Brief Review is to highlight literature that demonstrates how cytokines made by T lymphocytes impact the gastric epithelium, especially during Helicobacter pylori infection. These cytokines effect many of the diverse functions of the epithelium and the epithelium’s interactions with H. pylori. The focal point of this Brief Review will be on how T cell cytokines impact antimicrobial function and barrier function and how T cell cytokines influence the development and progression of cancer. Furthermore, the modulation of epithelial-derived chemokines by H. pylori infection will be discussed.
â€œIN PROIEZIONEâ€: SPAZIO E IMMAGINE IN LAS MENINAS DI DIEGO VELÃZQUEZ
Authors: Cocchiarella Luigi
Published: March 2020

This study focuses on the spatial analysis of Las Meninas, the worldwide well-known pictorial art masterpiece by Diego VelÃ¡zquez. Aesthetics, form, and symbolism, are here interlinked with a geometric pattern dependent on the exact location of the designated viewpoint, which severely obeys to the projective rules of linear perspective, where, as a gem in the gem, even the image of a mirror appears, to masterly highlight the final moral of the story, surprisingly explicated by the appeal to reflection. Sophisticated geometry feature and sublime graphic execution work together in this painting to establish the role of pictorial art as a creative besides imitative activity, representing painting itself in the very act of setting a pictorial reality, all this at the height of the so-called Golden Age of the Spanish art.
Implementation and Comparison of Model Co-Simulation Methods in a Turbofan Model
Authors: Krouse Charles , Nelson-Weiss Brendan
Published: March 2020

The process of developing, parameterizing, validating, and maintaining models occurs within a wide variety of tools, and requires significant time and resources. To maximize model utilization, models are often shared between various toolsets and experts. Model integration is typically divided into two categories: model exchange and model co-simulation. Of these two categories, model co-simulation is typically regarded as the more complex and difficult to implement. Co-Simulation provides the ability to integrate models between different toolsets or incompatible versions of the same software. Additionally, it provides the capabilities for real-time simulations and hardware-in-the-loop test scenarios. This paper reviews some of the common co-simulation data communication methods including pipes and file input/output. The differences between serial and parallel, aka synchronous and asynchronous, communication patterns are also discussed. A simple turbofan model was developed to demonstrate the aforementioned methods. The turbofan model was developed in a legacy version of NPSS, and this legacy model was integrated with a high-fidelity turbine model developed in a newer version of the NPSS software. The integration of the legacy turbojet model with the high-fidelity turbine is used to demonstrate how to integrate two models between incompatible software versions. This application can readily be extended to other co-simulation scenarios, such as real-time simulation. Integration of the two models was implemented using the aforementioned communication methods, synchronization mechanisms, and communication patterns. Relevant implementation details for the turbojet/turbine application are described, and a detailed discussion of the results and comparisons between different methods is provided.
Cable Impedance Calculations Employed in Designing Aerospace Electrical Power Systems
Authors: Fifield Jon
Published: March 2020

This paper presents design considerations in utilizing cable impedance calculations in the design of an aerospace electrical power system (EPS). Past wiring design guidelines featured a tabular set of data based on a single-point design reference. This results in a cable selection which adds unnecessary weight and under-utilized the wire’s performance ability when considering a vehicle’s design requirements. Present wiring design guidelines have lagged behind the growing movement to achieve an optimized wire selection. Understanding the shortfalls with past and present wiring design methods will improve future methods to comply with increasingly restrictive vehicle performance requirements. This paper will discuss two of the most important design requirements for future aerospace electrical power and distribution feeders, which are weight and thermal limits assigned to an EPS design.
Electrochemical Behavior of Screen-Printed Carbon Electrodes as Transducers in Biosensors
Authors: Dorledo de Faria Ricardo Adriano , Douaud Alexandre , Soares Renata Braga , Dias Heneine Luiz Guilherme , Matencio Tulio , Freitas Cunha Lins Vanessa de , Messaddeq Younès
Published: March 2020

Screen-printed carbon electrode (SPCE) was examined as a transducer substrate for application in electrochemical sensors. Aqueous solutions of 0.1 M KCl and 0.1 M KCl + 5 mM K3[Fe(CN)6]/K4[Fe(CN)6] (redox solution) were prepared to simulate the environment of faradaic and non-faradaic sensing, respectively. The SPCE presented an irregular surface composed by two main carbon phases. Raman spectroscopy results revealed the presence of peaks around 1,580 cm−1 and 1,334 cm−1 related to the G and D bands corresponding to sp2 carbon atoms (graphite flakes) and a multitude of broad bands associable to amorphous sp3 carbon in the ink matrix. Conductive atomic force microscopy indicated that the irregular structure of the SPCE led to the heterogeneous distribution of the current over the surface and the electroactivity of this material was mainly attributed to the presence of graphite. Polarization curves and electrochemical impedance spectroscopy (EIS) revealed that the redox solution was more aggressive to the SPCE, despite this electrode was achieved a quasi-steady state for 1 h under the effect of a polarization potential in both electrolytes, which justifies its use as an electrochemical transducer in faradaic and non-faradaic devices.
Acute renal artery stenting recovered renal function after spontaneous rupture of renal artery aneurysm – case report
Authors: Sojka Michał , Szmygin Maciej , Pyra Krzysztof , Kuczyńska Maryla , Jargiełło Tomasz
Published: March 2020

Purpose: Renal artery aneurysms (RAAs) are a rare vascular pathology with an estimated prevalence of 0.1% to 2.5%. Rupture of RAA is an extremely unusual cause of acute flank pain and haemodynamic instability with acute kidney failure and high mortality rate (20%).

Case report: A 37-year-old male with no relevant history presented to the Emergency Room with acute right flank pain. Initial examination revealed BP 90/60 mm Hg and tachycardia. Initial blood testing was unremarkable, with a haemoglobin level of 9.4 g/dl. Urinalysis revealed moderate blood. Ultrasound (US) examination depicted aneurysm of the right renal artery 6 x 6 cm, with signs of blood extravasation visible in colour and power Doppler. The patient was referred for urgent computed tomography angiography, which revealed active bleeding from the ruptured aneurysm with haematoma spreading into the right retroperitoneum. He was subjected to emergency endovascular treatment. The patient was treated by successful implantation of a Viabahn stent (GORE, Daleware, USA). Selective nephrography revealed lack of flow through one of the segmental arteries resulting from vasospasm due to the placement of the guiding wire necessary for safe stent implantation.

Conclusions: The authors present a rare case of spontaneous RAA rupture in a young male successfully treated with endovascular methods. Stent implantation required selective catheterisation of segmental arteries of the kidney, which resulted in the loss of one of them. However, control Doppler US disclosed no ischaemia and successful exclusion of the aneurysm.
Hydrological variations in central China over the past millennium and their links to the tropical Pacific and North Atlantic oceans
Authors: Duan Fucai , Zhang Zhenqiu , Wang Yi , Chen Jianshun , Liao Zebo , Chen Shitao , Shao Qingfeng , Zhao Kan
Published: March 2020

Abstract. Variations of precipitation, also called the Meiyu rain, in the East Asian
summer monsoon (EASM) domain during the last millennium could help enlighten
the hydrological response to future global warming. Here we present a
precisely dated and highly resolved stalagmite δ18O record from
the Yongxing Cave, central China. Our new record, combined with a previously
published one from the same cave, indicates that the Meiyu rain has changed
dramatically in association with the global temperature change. In
particular, our record shows that the Meiyu rain was weakened during
the Medieval Climate Anomaly (MCA) but intensified during the Little Ice
Age (LIA). During the Current Warm Period (CWP), our record indicates a
similar weakening of the Meiyu rain. Furthermore, during the MCA and CWP,
our records show that the atmospheric precipitation is similarly wet in
northern China and similarly dry in central China, but relatively wet during
the CWP in southern China. This spatial discrepancy indicates a complicated
localized response of the regional precipitation to the anthropogenic
forcing. The weakened (intensified) Meiyu rain during the MCA (LIA) matches
well with the warm (cold) phases of Northern Hemisphere surface air
temperature. This Meiyu rain pattern also corresponds well to the climatic
conditions over the tropical Indo-Pacific warm pool. On the other hand, our
record shows a strong association with the North Atlantic climate as well.
The reduced (increased) Meiyu rain correlates well with positive (negative)
phases of the North Atlantic Oscillation. In addition, our record links well
to the strong (weak) Atlantic meridional overturning circulation during
the MCA (LIA) period. All abovementioned localized correspondences and
remote teleconnections on decadal to centennial timescales indicate that the
Meiyu rain was coupled closely with oceanic processes in the tropical Pacific
and North Atlantic oceans during the MCA and LIA.
Evaluation of isotopes and elements in planktonic foraminifera from the Mediterranean Sea as recorders of seawater oxygen isotopes and salinity
Authors: Dämmer Linda K. , de Nooijer Lennart , van Sebille Erik , Haak Jan , Reichart Gert-Jan
Published: March 2020

Abstract. The Mediterranean Sea is characterized by a relatively strong west to east salinity gradient, which makes it an area suitable to test the effect of salinity on foraminiferal shell geochemistry. We collected living specimens of the planktonic foraminifer Globigerinoides ruber (white) to analyse the relation between element/Ca ratios, stable oxygen isotopes of their shells and surface seawater salinity, isotopic composition and temperature. The oxygen isotopes of sea surface water correlate with salinity in the Mediterranean also during winter, when sampled for this study. Sea water oxygen and hydrogen isotopes are positively correlated in both the eastern and western Mediterranean Sea, though especially in the eastern part the relationship differs from values reported previously for that area. The slope between salinity and seawater oxygen isotopes is lower than previously published. Still, despite the rather modest slope, seawater and foraminiferal carbonate oxygen isotopes are correlated in our dataset although with large residuals and high residual variability. This scatter can be due to either biological variability in vital effects or environmental variability. Numerical models backtracking particles show ocean current driven mixing of particles of different origin might dampen sensitivity and could result in an offset caused by horizontal transport. Results show that Na/Ca is positively correlated to salinity and independent of temperature. Foraminiferal Mg/Ca increases with temperature, as expected, and in line with earlier calibrations, also in the high salinity environment. By using living foraminifera during winter, the previously established Mg/Ca-temperature calibration is extended to temperatures below 18 °C, which is a fundamental prerequisite of using single foraminifera for reconstructing past seasonality.
Analysis and management of unexpected and cumulative climate risks in Switzerland
Authors: Neukom Raphael , Salzmann Nadine , Huggel Christian , Mucchione Veruska , Kleppek Sabine , Hohmann Roland
Published: March 2020

The study on ‘climate-related risks and opportunities’ of the Swiss Federal Office for the Environment (FOEN) provides a comprehensive analysis of climate-related risks and opportunities for Switzerland until 2060. The synthesis of the study results has been the basis for the development of adaptation strategies and measures in Switzerland. The study also identifies knowledge gaps and related missing planning tools for risks, which are difficult to assess as they typically have a low probability of occurrence but have potentially very high impacts for society and/or the environment. Such risks refer in particular to risks, which cumulate through process cascades or are triggered by meteorological/climatic extremes events, which return within shorter time intervals than expected.

To respond to these gaps, a collaborative effort including academic and government institutions at different administrative levels is undertaken in order to explore and analyse the potential of such cumulative risks and actions needed to manage them in Switzerland. The project focuses on two case studies, which are developed in consultation with stakeholders from science, policy and practice at the national and sub-national level.

The case studies analyse risks triggered by meteorological events based on projected and recently published Swiss Climate Scenarios CH2018, considering rare but plausible scenarios where such triggering events cumulate and/or occur in combinations.

We discuss international terminologies and experience with unexpected and cumulative extreme events and put them in relation to the Swiss context. Specifically, we present the cascading processes of the first case study, which focuses on the protective forests in the eastern Swiss Alps. Potential reduction of the protective capacity caused by extreme drought and heat and subsequent increase of risks caused by multiple natural hazards, such as fires and mass movements (snow avalanche, landslide), are assessed in this case study using semi-quantitative methods of risk analysis.
Another drought or more pesky humans? Anthropogenic impacts leave drought-like sedimentological signatures in offshore sediments
Authors: Kalman Akos , Katz Timor , Mathalon Alysse , Hill Paul , Goodman-Tchernov Beverly
Published: March 2020

Worldwide, rivers deliver sediments and nutrients into the marine system, and this discharge is naturally variable due to fluctuations in precipitation, climate, and the shifting morphology of river channels. The sedimentological fingerprint of these variations from cores has been used to reconstruct past trends and conditions. Today, many coastal rivers have been heavily altered by dam construction, flood control, harbors, irrigation canals, and other human activities; thus also changing the volume, location, and arrival intervals of sediment discharge into the shallow marine shelf. Therefore, differentiating between changes linked to natural versus anthropogenic causes is key to interpreting and understanding the long-term effects of human activity and better defining the Anthropocene in the sedimentological record. In this study, offshore sediment profiles from the shallow shelf northern Red Sea were used to investigate how their recent sedimentological signatures compare to those of the past few thousand years, during which larger climatic shifts influenced sedimentation. The results found that the sedimentological trends were more homogenous laterally prior to the most recent half century, after which channelization of the alluvial plain directed the majority of flashflood runoff to a single outlet. This led to an artificial ‘drought-like’ signature in areas recently cut-off from incoming sediments. Data from sediment cores collected from offshore the Mediterranean coast of Israel inside the Nile littoral cell, an area that may have been impacted by the immense decrease in sediment discharge from the Nile river following the building of the High Aswan Dam showed similar trends. The impact that anthropogenic manipulation has on river sedimentary discharge, and its sedimentary signature will be discussed.
Impact of stratospheric ozone on the subseasonal prediction skill in the Southern Hemisphere spring
Authors: Oh Jiyoung , Son Seok-Woo , Han Bo-Reum
Published: March 2020

The Antarctic polar vortex and the associated ozone change have been recognized as a key factor that influences both local and large-scale circulations in the Southern Hemisphere (SH) extratropics. Their downward impacts are also evident in the subseasonal-to-seasonal (S2S) and long-term climate predictions especially in austral spring and summer. However, most operational S2S models, including the Global Seasonal Forecasting System version 5 (GloSea5), use climatological ozone and ignore time-varying ozone associated with polar vortex variability. This study explores the possible impact of stratospheric ozone on SH S2S prediction skill by conducting the two sets of reforecast experiments with the GloSea5. The reforecasts are initialized on 1st September of every year for the period of 2004-2018 with either climatological or observed ozone from the Stratospheric Water and OzOne Satellite Homogenized (SWOOSH) data. It turns out that the reforecasts with observed ozone have an improved prediction skill at 5- and 6-week lead forecasts than those with climatological ozone. The surface prediction skills also increase over the southern Australia and New Zealand. These results suggest that more realistic stratospheric ozone forcing could improve the SH prediction skill on subseasonal-to-seasonal timescale.
Resolving dynamic ground motions with high-rate GNSS and implications for data fusion in broadband seismology and Earthquake Early Warning
Authors: Hohensinn Roland , Dahmen Nikolaj , Clinton John , Geiger Alain , Rothacher Markus
Published: March 2020

In this paper we highlight the potential of geodetic high-precision and high-rate GNSS (Global Navigation Satellite System) sampling (1 to 100 Hz) for resolving seismic ground motions, of both the near and the far field of an earthquake. The analysis of the budget and characteristics of the error of high-rate GNSS displacement time series yields results, discussion, and conclusions on the sensitivity and waveform resolvability as well as on the derivation of a minimum detectable displacement (in the statistical sense).

Based on these analyses, we show how GNSS can contribute to optimal broadband displacement and velocity waveform products by means of data fusion by combining measurements taken from co-located sensors – e.g. accelerometers or gyroscopes – in real-time, near real-time and postprocessing mode. Concerning the inclusion of GNSS for such an analysis, we also briefly explore the ability of GNSS to record signals from different earthquake magnitudes and epicentral distances. We show that high-rate GNSS is sensitive to displacements down to the level of a few millimeters, and even below – an example also comes from the detection of very small vibrations from 100 Hz GNSS data.

We analyze measurements of synthetized signals obtained from experiments with a shake table, as well as from real data from strong earthquakes, namely the 6.5 Mw event of 2016 near the city of Norcia (Italy) and the 7.0 Mw Kumamoto earthquake of 2016 (Japan). Based on these data and our main findings, we finally discuss the role of GNSS in Earthquake Early Warning in terms of a fast hypocenter localization and reliable magnitude estimation.
On the persistence of tropical shallow convective squall lines - the role of cold pools
Authors: Touzé-Peiffer Ludovic , Rochetin Nicolas , Vogel Raphaela
Published: March 2020

A considerable amount of literature has been devoted to the study of strong convective squall line. In particular, many studies have noted the role of cold pools on the persistence of these squall lines. Observations and simulations have shown that squall lines are often associated with pools of air cooled by partial rain evaporation. Such cold pools spread at the surface and may initiate new convective cells at their edges, thus contributing to the maintenance of a squall line. Under which environmental conditions the lifting at the edges of cold pools is most efficient has been subject to many debates. Yet, it is generally acknowledged that the environmental wind shear is a critical factor in this process. 

Recent observations and realistic simulations over the trade-wind region have revealed persistent structures of shallow cumuli associated with surface cold pools. We will call these structures shallow convective squall lines, due to their similarity with strong convective squall lines. Based on simulations from the German model ICON and on recent observations from the field campaign EUREC4A, we will study the characteristics of these shallow convective squall lines and their lifecycle. Similarly to strong convective squall lines, shallow convective squall lines organized around a leading edge composed by many updrafts and downdrafts feeding the surface cold pools. We will see that the environmental wind shear plays a key role in the persistence of these shallow convective squall line, and we will compare our findings with classical theories for strong convective squall lines.
P-wave tomographic model from local bulletin data for improved seismic location in and around Israel
Authors: Schardong Lewis , Ben-Horin Yochai , Ziv Alon , Wust-Bloch Hillel , Radzyner Yael
Published: March 2020

For the past 40 years, the Geophysical Institute of Israel has been in charge of the recording, monitoring and relocating of local earthquakes. Due to the variety of data analysts and data sources, as well as several network upgrades, the resulting bulletin data has to be completed and homogenised, and station metadata needs to be tracked down, and sometimes corrected. For those reasons, as well as because of the lack of consensus on an accurate model for seismic velocities in the area, published source locations are often poorly constrained. We present a homogenised Israeli bulletin, including natural and man-made explosion data. We extract sets of seismic sources with location accuracy greater than 5 km (GT5), as well as GT0 explosions.

We select a set of events with the highest network coverage, comprising (1) natural earthquakes, (2) man-made quarry or mine blasts, (3) GT5 earthquakes or explosions, and (4) GT0 explosions. We relocate them altogether using the BayesLoc package, a Bayesian, hierarchical, multi-event locator which produces, after source relocation, event-, station- and phase-specific correction terms. We put different a priori constraints on the different categories of seismic events, allowing poorly constrained origin parameters to improve thanks to the more accurate GT locations. BayesLoc also produces traveltime correction terms that can be used to correct systematic errors in the dataset, as well as error estimates.

Eventually, we invert this homogenised local traveltime dataset in order to invert for a P-wave crustal velocity model of Israel and its surroundings. To do so, we use the Fast Marching Tomography package, which allows the representation of a wide variety of input structures (starting model and geometry of layer boundaries) and can take many different types of input data. We show preliminary inversion tests and results that are in good agreement with past local studies.

This crustal model of Israel is ultimately to be used as a starting model in a larger tomographic study of the Eastern Mediterranean and Middle East region, where the Regional Seismic Travel Time approach is to be expanded, in order to improve the CTBT’s capabilities in monitoring the regional seismicity. Eventually, such a velocity model could also be used to relocate the whole earthquake catalogue more accurately, and improve the Earthquake Early Warning System currently in development in Israel.
Faulting in Mars Polar Layered deposits modeled by HCA method
Authors: Cianfarra Paola , Rossi Costanza , Salvini Francesco , Crispini Laura
Published: March 2020

The polar layered deposits (PLD) of Mars constitute the water ice stratigraphy of polar spiral troughs up to several kilometers thick (Phillips et al., 2011; Smith et al. 2015). PLD cross section profiles from the Shallow Subsurface Radar (SHARAD) instrument on NASA’s Mars Reconnaissance Orbiter, show the presence of internal discontinuities within these layers (Foss et al., 2017; Putzig et al., 2017). The mechanisms responsible for these deformations are still an open issue (Guallini et al., 2017) and this work represents the contribution of stress-related deformations. Layered ice is simulated by a mesh of cells within a HCA grid build replicating the physical properties and preserving volumes following balanced cross-section principles. Three major types of link exist among adjacent cells: 1. intra-layer relations link cells belonging to the same layer; 2. inter-layer relations regulate the relationships among adjacent layers; 3. discontinuity relations correspond to the presence of ruptures such as faults (Salvini et al., 2001). The HCA method allows to replicate the natural material anisotropies, such as rocks and ice sheet internal layering, and to simulate complex tectonic evolutionary paths (Cianfarra and Salvini, 2016; Cianfarra and Maggi, 2017). The models allow simulating the kinematics of the internal architecture of the layered deposits from both the north and the south Martian ice caps. In particular the observed stratigraphy (geometries and thickness of the ice layers) is replicated as resulting from the relative, normal movement among blocks separated by listric shaped normal faults and minor inversions.

The used HCA numerical methodology revealed an effective tool to support planetary geological mapping and 3D subsurface geological reconstructions. Through the integration of a net of spatially distributed along- and across- strike (balanced) sections it is possible to simulate the 4D (3D plus time) geological evolution of buried and/or topographic structures. Results have a wide range of applications including the optimal selection of landing sites for scheduled and future planetary exploration missions, as well as unravelling the geological and structural setting of enigmatic features on the planetary surfaces affected, for example, by salt tectonism, volcano-tectonics, tectonically-related hydrothermal activity, fluid storage and release, and ice tectonics.
Bayesian filtering for incoherent scatter radar analysis
Authors: Tesfaw Habtamu , Virtanen Ilkka , Aikio Anita , Roininen Lassi , Lasanen Sari
Published: March 2020

Electron precipitation and ion frictional heating events cause rapid variations in electron temperature, ion temperature and F1 region ion composition of the high-latitude ionosphere. Four plasma parameters: electron density, electron temperature, ion temperature, and plasma bulk velocity, are typically fitted to incoherent scatter radar (ISR) data.

Many ISR data analysis tools extract the plasma parameters using an ion composition profile from an empirical model. The modeled ion composition profile may cause bias in the estimated ion and electron temperature profiles in the F1 region, where both atomic and molecular ions exist with a temporally varying proportion.

In addition, plasma parameter estimation from ISR measurements requires integrating the scattered signal typically for tens of seconds. As a result, the standard ISR observations have not been able to follow the rapid variations in plasma parameters caused by small scale auroral activity.

In this project, we implemented Bayesian filtering technique to the EISCAT’s standard ISR data analysis package, GUISDAP. The technique allows us to control plasma parameter gradients in altitude and time.

The Bayesian filtering implementation enabled us to fit electron density, ion and electron temperatures, ion velocity and ion composition to ISR data with high time resolution. The fitted ion composition removes observed artifacts in ion and electron temperature estimates and the plasma parameters are calculated with 5 s time resolution which was previously unattainable.

Energy spectra of precipitating electrons can be calculated from electron density and electron temperature profiles observed with ISR. We used the unbiased high time-resolved electron density and temperature estimates to improve the accuracy of the estimated energy spectra. The result shows a significant difference compared to previously published results, which were based on the raw electron density (backscattered power) and electron temperature estimates calculated with coarser time resolution.

 
A Stable and Efficient Flood Routing Model Based on Unstructured Grid
Authors: Zhou Shan , Hu Hongchang
Published: March 2020

Godunov-type schemes are widely applied to solve shallow water equations. In this study, a novel non-negative water depth Multislope MUSCL reconstruction method is incorporated into a two-dimensional unstructured cell-centered Godunov-type finite volume model to simulate shallow water flows, It is verified that the method performs well in avoiding non-physical oscillation and also has well-balanced performance by simulate three test cases. Due to the limitation of CFL conditions, mesh refinement will greatly increase the computational cost. In this study, A Local Time Stepping(LTS) strategy is specifically designed to greatly improve the computational efficiency. In addition, in order to make the model suitable for more application scenarios, we have realized the coupling of one-dimensional and two-dimensional models. Based on the above three improvements, we have developed a stable and efficient flood routing model.
Global Geodetic Observing System
Authors: Miyahara Basara
Published: March 2020

The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) provides the basis on which future advances in geosciences can be built. By considering the Earth system as a whole (including the geosphere, hydrosphere, cryosphere, atmosphere and biosphere), monitoring Earth system components and their interactions by geodetic techniques and studying them from the geodetic point of view, the geodetic community provides the global geosciences community with a powerful tool consisting mainly of high-quality services, standards and references, and theoretical and observational innovations. The mission of GGOS is: (a) to provide the observations needed to monitor, map and understand changes in the Earth’s shape, rotation and mass distribution; (b) to provide the global frame of reference that is the fundamental backbone for measuring and consistently interpreting key global change processes and for many other scientific and societal applications; and (c) to benefit science and society by providing the foundation upon which advances in Earth and planetary system science and applications are built. The goals of GGOS are: (1) to be the primary source for all global geodetic information and expertise serving society and Earth system science; (2) to actively promote, sustain, improve, and evolve the integrated global geodetic infrastructure needed to meet Earth science and societal requirements; (3) to coordinate with the international geodetic services that are the main source of key parameters and products needed to realize a stable global frame of reference and to observe and study changes in the dynamic Earth system; (4) to communicate and advocate the benefits of GGOS to user communities, policy makers, funding organizations, and society. In order to accomplish its mission and goals, GGOS depends on the IAG Services, Commissions, and Inter-Commission Committees. The Services provide the infrastructure and products on which all contributions of GGOS are based. The IAG Commissions and Inter-Commission Committees provide expertise and support for the scientific development within GGOS. In summary, GGOS is IAG’s central interface to the scientific community and to society in general. The whole figure of GGOS and its recent focus will be presented in the presentation.
Thermodynamic consistent formulation for the multiphysics of a brittle ductile lithosphere - semi-brittle semi-ductile deformation and damage rheology
Authors: Cacace Mauro , Jacquey Antoine
Published: March 2020

We provide details on a novel formulation derived to describe the multiphysics controlling the deformation of porous rock under lithospheric conditions. The theory is developed consistent with the principles of thermodynamics and enables to capture the behaviour of porous rocks at the transition from frictional brittle behaviour to ductile viscous behaviour. It also accounts for the nonlinear feedback mechanisms derived from energetic consideration for the bi-phasic fluid-rock matrix system.

The formulation depicts a consistent, implicit visco-elasto-(visco)plastic rheology accounting for both a volumetric and a deviatoric response to applied loads, thereby avoiding the use of, the commonly assumed, plasticity limiter concept. The overstress plastic formulation introduces rate dependent mechanical behavior, an aspect that is consistent with experimental rock mechanics evidence and is also demonstrated to improve numerical stability when addressing problems related to plastic strain accumulation even in the absence of energetic feedbacks.

The introduction of a damage rheology permits to account for microstructural processes responsible for brittle-like material weakening and rate-dependent dissipative material behavior. The presence of a fluid phase is considered via a dynamic porosity, the evolution of which is demonstrated to primarily control the volumetric mechanical response of the stressed rock during incremental loading.

The above formulation has been integrated in a massively parallel, open source numerical framework with interfaces to state of the art HPC clusters. The results of a scalability and profile performance analysis on multi-core supercomputer are presented alongside with dedicated applications describing lithospheric rock deformation under different confining conditions as well as the bulk macroscopic material response recorded by laboratory experiments under triaxial conditions.
Improving Dryland Crop Simulation by Assimilating Soil Moisture and Vegetation Data
Authors: Lu Yang , Sheffield Justin
Published: March 2020

Global population is projected to keep increasing rapidly in the next 3 decades, particularly in dryland regions of the developing world, making it a global imperative to enhance crop production. However, improving current crop production in these regions is hampered by yield gaps due to poor soils, lack of irrigation and other management practices. Here we develop a crop modelling capability to help understand gaps, and apply to dryland regions where data for parametrizing and testing models is generally lacking. We present a data assimilation framework to improve simulation capability by assimilating in-situ soil moisture and vegetation data into the FAO AquaCrop model. AquaCrop is a water-driven model that simulates canopy growth, biomass and crop yield as a function of water productivity. The key strength of AquaCrop lies in the low requirement for input data thanks to its simple structure. A global sensitivity analysis is first performed using the Morris screening method and the variance-based Extended Fourier Amplitude Sensitivity Test (EFAST) method to identify the key influential parameters on the model outputs. We begin with state-only updates by assimilating different combinations of soil moisture and vegetation data (vegetation indices, biomass, etc.), and different filtering/smoothing assimilation strategies are tested. Based on the state-only assimilation results, we further evaluate the utility of joint state-parameter (augmented-states) assimilation in improving the model performance. The framework will eventually be extended to assimilate remote sensing estimates of soil moisture and vegetation data to overcome the lack of in-situ data more generally in dryland regions.
Machine learning as a tool for avalanche forecasting
Authors: Hendrick Martin , Pérez-Guillén Cristina , van Herwijnen Alec , Schweizer Jürg
Published: March 2020

Assessing and forecasting avalanche hazard is crucial for the safety of people and infrastructure in mountain areas. Over 20 years of data covering snow precipitation, snowpack properties, weather, on-site observations, and avalanche danger has been collected in the context of operational avalanche forecasting for the Swiss Alps. The quality and breadth of this dataset makes it suitable for machine learning techniques.

Forecasters mainly process a huge and redundant dataset "manually" to produce daily avalanche bulletins during the winter season. The purpose of this work is to provide the forecasters automated tools to support their work. 

By combining clustering and classification algorithms, we are able to reduce the amount of information that needs to be processed and identify relevant weather and snow patterns that characterize a given avalanche situation.
Community tsunami inundation maps for selected ICG/CARIBE EWS member states
Authors: Sánchez-Linares Carlos , Macías Jorge , Aniel-Quiroga Íñigo , Aguirre-Ayerbe Ignacio , González Mauricio , Aliaga Bernardo
Published: March 2020

The Intergovernmental Coordination Group for the Tsunami and other Coastal Hazards Warning System for the Caribbean and Adjacent Regions (ICG/CARIBE EWS) was established in 2005 as a subsidiary body of the IOC-UNESCO with the purpose of providing efficient assistance on tsunami risk reduction to Member States in the Caribbean region after the lessons learnt from the 2004 Indian Ocean tsunami.

 

The aim of the work that we present here, is strengthen the capacities of early warning and response for tsunamis in the Caribbean through the development of community-level tsunami inundation maps for select coastal communities and a technical guide; both to support their preparation for and response to tsunamis. The selected communities under study are in Antigua and Barbuda, Barbados, Dominican Republic, St. Vincent and the Grenadines, and Trinidad and Tobago.

 

To this end, we use Tsunami-HySEA model, developed by EDANYA Group, which implements in the same code the three phases of an earthquake generated tsunami: generation, propagation and coastal inundation. At the same time it is implemented in nested meshes with different resolution and multi-GPU environment, which allows much faster than real time simulations. Due to this advantage it can produce a 4 h simulation in a 60 arcsec resolution grid for the whole Caribbean Sea in less than 4 min with a single general-purpose GPU.

 

Once provided the seismic parameters to reproduce the main scenarios that could affect to the nominated communities, and the topobathymetry data available from the study area, an exhaustive process of construction of 4 levels nested meshes was performed for each localization. Secondly, the events are simulated in order to obtain, among others, maximum depth in coast inundation with 5 meters resolution. Finally, all of these data allow us to make a detailed inundation map as a contribution to furthering tsunami risk assessment.

 

Acknowledgements. This work was done under the auspices of IOC-UNESCO and funded by EU (DG-ECHO)