bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single‐Station Lightning Location Using Azimuth and Time of Arrival of Sferics
Authors: Koochak Zahra , Fraser‐Smith Antony 
Published: December 2019

AbstractLightning strikes produce electromagnetic waves, now referred to as sferics, in the very low frequency (3 kHz–30 kHz) and the extremely low frequency (3 Hz–3 kHz) bands. Within these frequency bands, the Earth and ionosphere form a waveguide in which sferics propagate long distances with low attenuation. The structure of the received sferic waveform is mainly a function of propagation distance and the waveguide's parameters. This suggests that each observed sferic waveform contains information about the distance that this sferic has propagated which can be used to geolocate lightning. There are various approaches for analyzing received sferics, which mostly rely on measurements from multiple stations. However, in these methods, each station imposes an additional cost for building, maintenance, and synchronization. Here we present a novel method to estimate both the emission time and location of lightning, which works by measuring sferics recorded at a single station. We first process the sferic waveforms to obtain the arrival times of the very low frequency and extremely low frequency radiation components which propagate with different speeds. Once these two separate arrival times are determined, we use them to approximate the distance the sferic propagated in the Earth‐ionosphere waveguide. We have used this novel method in combination with a method to find sferic direction to geolocate a significant number of lightning strikes for 4 July 2013. Using this proposed method, the distance of propagation estimates are accurate to within 6.7% of the National Lightning Detection Network‐determined propagation distance, and the direction of propagation estimates are accurate to within
1.3% of the National Lightning Detection Network‐determined direction.
Drift‐Bounce Resonance Between Charged Particles and Ultralow Frequency Waves: Theory and Observations
Authors: Zhu Yi‐Fan , Gu Shu‐Jie , Zhou Xu‐Zhi , Zong Qiu‐Gang , Ren Jie , Sun Xin‐Ran , Liu Ying , Zhang Shuai , Shi Quanqi , Rankin Robert 
Published: December 2019

AbstractUltralow frequency (ULF) waves have long been known to resonate with magnetospheric charged particles through their drift and bounce motions. Most research interest has focused on the resonance with drift motion, which can accelerate charged particles at very high energies. The role of the bounce motion, especially for particles with lower energies, has attracted less attention so far. Here we start from the general theory of wave‐particle interactions to predict the characteristic, observable signatures of drift‐bounce resonance. Such signatures can be described in the particle pitch angle spectrum as a series of inclined stripes, with the inclination angle depending on the latitude of the observing spacecraft. Each stripe is also twisted at two conjugated pitch angles, suggesting significant phase shifts across resonant pitch angles. These predicted signatures are found consistent with observations from the THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft, and therefore provide an identification of drift‐bounce resonance together with a validated picture over the importance of particle's bounce motion in the ULF wave‐particle interactions.
Statistics of Reconnecting Current Sheets in the Transition Region of Earth's Bow Shock
Authors: Gingell I. , Schwartz S. J. , Eastwood J. P. , Stawarz J. E. , Burch J. L. , Ergun R. E. , Fuselier S. A. , Gershman D. J. , Giles B. L. , Khotyaintsev Y. V. , Lavraud B. , Lindqvist P.‐A. , Paterson W. R. , Phan T. D. , Russell C. T. , Strangeway R. J. , Torbert R. B. , Wilder F. 
Published: December 2019

AbstractWe have conducted a comprehensive survey of burst mode observations of Earth's bow shock by the Magnetospheric Multiscale mission to identify and characterize current sheets associated with collisionless shocks, with a focus on those containing fast electron outflows, a likely signature of magnetic reconnection. The survey demonstrates that these thin current sheets are observed within the transition region of approximately 40% of shocks within the burst mode data set of Magnetospheric Multiscale. With only small apparent bias toward quasi‐parallel shock orientations and high Alfvén Mach numbers, the results suggest that reconnection at shocks is a universal process, occurring across all shock orientations and Mach numbers. On examining the distributions of current sheet properties, we find no correlation between distance from the shock, sheet width, or electron jet speed, though the relationship between electron and ion jet speed supports expectations of electron‐only reconnection in the region. Furthermore, we find that robust heating statistics are not separable from background fluctuations, and thus, the primary consequence of reconnection at shocks is in relaxing the topology of the disordered magnetic field in the transition region.
Comparison of Multiple and Logistic Regression Analyses of Relativistic Electron Flux Enhancement at Geosynchronous Orbit Following Storms
Authors: Capman N.S.S. , Simms L.E. , Engebretson M.J. , Clilverd M.A. , Rodger C.J. , Reeves G.D. , Lessard M.R. , Gjerloev J. 
Published: December 2019

AbstractMany factors influence relativistic outer radiation belt electron fluxes, such as waves in the ultralow frequency (ULF) Pc5, very low frequency (VLF), and electromagnetic ion cyclotron (EMIC) frequency bands, seed electron flux, Dst disturbance levels, substorm occurrence, and solar wind inputs. In this work we compared relativistic electron flux poststorm versus prestorm using three methods of analysis: (1) multiple regression to predict flux values following storms, (2) multiple regression to predict the size and direction of the change in electron flux, and (3) multiple logistic regression to predict only the probability of the flux rising or falling. We determined which is the most predictive model and which factors are most influential. We found that a linear regression predicting the difference in prestorm and poststorm flux (Model 2) results in the highest validation correlations. The logistic regression used in Model 3 had slightly weaker predictive abilities than the other two models but had the most value in providing a prediction of the probability of the electron flux increasing after a storm. Of the variables used (ULF Pc5 and VLF, seed electrons, substorm activity, and EMIC waves), the most influential in the final model were ULF Pc5 waves and the seed electrons. IMF Bz, Dst, and solar wind number density, velocity, and pressure did not improve any of the models, and were deemed unnecessary for effective predictions.
Radiometric Temperature Measurements in Nongray Ferropericlase With Pressure‐ Spin‐ and Temperature‐Dependent Optical Properties
Authors: Lobanov Sergey S. , Speziale Sergio 
Published: December 2019

AbstractAccurate temperature determination is central to measurements of physical and chemical properties in laser‐heated (LH) diamond anvil cells (DACs). Because the optical properties of samples at high pressure‐temperature (P‐T) conditions are generally unknown, virtually all LH DAC studies employ the graybody assumption (i.e., wavelength‐independent emissivity and absorptivity). Here we test the adequacy of this assumption for ferropericlase (13 mol.% Fe), the second most abundant mineral in the Earth's lower mantle. We model the wavelength‐dependent emission and absorption of thermal radiation in samples of variable geometry and with absorption coefficients experimentally constrained at lower mantle P and P‐T. The graybody assumption in LH DAC experiments on nongray ferropericlase contributes moderate systematic errors within ±200 K at 40, 75, and 135 GPa and T < 2300 K for all plausible sample geometries. However, at core‐mantle boundary P‐T conditions (135 GPa, 4000 K) the graybody assumption may underestimate the peak temperature in the DAC by up to 600 K in self‐insulated samples due to selective light attenuation in highly opaque ferropericlase. Our results allow insights into the apparent discrepancy between available ferropericlase melting studies and offer practical guidance for accurate measurements of its solidus in LH DACs. More generally, the results of this work demonstrate that reliable temperature measurements in LH DACs require that the optical and geometrical properties of the samples are established.
Carbon Partitioning Between the Earth's Inner and Outer Core
Authors: Li Yunguo , Vočadlo Lidunka , Alfè Dario , Brodholt John 
Published: December 2019

AbstractKnowledge of the abundance and distribution of light elements in the core is fundamental to the understanding of the Earth and other planetary systems. Recent studies (Li et al., 2018; Mashino et al., 2019) suggest the particular importance of carbon for explaining core properties, yet knowledge of carbon partitioning between the outer and inner core is unknown. By using the quasiharmonic approximation, ab initio molecular dynamics, and thermodynamic integration techniques, we have computed the chemical potential of carbon in liquid Fe and solid hcp‐Fe at core conditions. We find that substitutional carbon is more stable than interstitial carbon and other carbon defect cluster structures in solid Fe. Lattice strain and overcoordination effects lead to a high chemical potential of C in solid Fe compared to the liquid, and consequently carbon partitions almost completely into the liquid. We find that carbon can account for most of the density jump at the inner‐core boundary. This provides an alternative mechanism to the necessity of an oxygen‐rich outer core and may have significant implications for the composition and structure of the deep Earth.
An asymptotically compatible approach for Neumann-type boundary condition on nonlocal problems
Authors: You Huaiqian , Lu XinYang , Task Nathaniel , Yu Yue 
Published: December 2019

In this paper we consider 2D nonlocal diffusion models with a finite nonlocal horizon parameterδcharacterizing the range of nonlocal interactions, and consider the treatment of Neumann-like boundary conditions that have proven challenging for discretizations of nonlocal models. We propose a new generalization of classical local Neumann conditions by converting the local flux to a correction term in the nonlocal model, which provides an estimate for the nonlocal interactions of each point with points outside the domain. While existing 2D nonlocal flux boundary conditions have been shown to exhibit at most first order convergence to the local counter part asδ → 0, the proposed Neumann-type boundary formulation recovers the local case asO(δ2) in theL∞(Ω) norm, which is optimal considering theO(δ2) convergence of the nonlocal equation to its local limit away from the boundary. We analyze the application of this new boundary treatment to the nonlocal diffusion problem, and present conditions under which the solution of the nonlocal boundary value problem converges to the solution of the corresponding local Neumann problem as the horizon is reduced. To demonstrate the applicability of this nonlocal flux boundary condition to more complicated scenarios, we extend the approach to less regular domains, numerically verifying that we preserve second-order convergence for non-convex domains with corners. Based on the new formulation for nonlocal boundary condition, we develop an asymptotically compatible meshfree discretization, obtaining a solution to the nonlocal diffusion equation with mixed boundary conditions that converges withO(δ2) convergence.
The role of inertia on a locally favoured structure in equimolar binary mass Hard Spheres
Authors: Pinchaipat Rattachai , Wongrach Kunaree 
Published: December 2019

Abstract
Molecular dynamics simulations have been carried out to investigate the effect of inertia on both dynamics and locally favoured structures (LFS) of a supercooled liquid toward glass transition. In this work, the equimolar supercooled liquid binary mixtures of Hard Spheres with the same diameter but different masses were studied. The mass ratio of the binary system was 2:1. The simulation was performed and sampled by using the microcanonical ensemble. Both dynamics and structure changing were analysed. A cluster structure analysis was detected by topological cluster classification (TCC) based on the results of local free energy minimisation. The slowing down dynamics were found to be related to cluster structure changing in both the binary mass Hard Sphere (BMHS) and Hard Sphere (HS). The inertia affected an increasing dynamical heterogeneity and had some effects on favouring some local structures before they get crystallisation.
Tarnish resistance of silver by gold microplates coating
Authors: Rattanapoltee P , Thongnopkun P 
Published: December 2019

Abstract
Silver is a promising precious metal for the jewelry industry. The silver jewelry findings exposed to air would be tarnished because it comes into contact with sulfur particles in atmospheres. Therefore, surface treatments and coating methods were developed to prevent the tarnishing of silver. However, the methods still have several limitations and disadvantages. The objective of this research was to develop gold microplates for surface coating and tarnish resistance of silver. In this study, the gold microplates were synthesized by chemical reduction methods. Multilayer gold coating was performed by a simple dip coating method to produce the gold film using a gold microplate solution, which disperses gold particles in ethylene glycol. The anti-tarnish properties of the coated silvers were investigated using the sodium sulphide solution. To specify the color change after multilayer coatings of gold particles and tarnishing test, the color measurement was determined according to the Commission Internationale d’ Eclairage (CIELAB) standard by UV-visible spectrometer. The result pointed out that the gold microplates layers coating on silver are invisible and efficiently prevents tarnishing.
Crustal body–wave velocities beneath Thailand from teleseismic analysis
Authors: Yongsiriwith P , Khoonphunnarai P , Daoh M 
Published: December 2019

Abstract
We estimated the crustal seismic body-wave velocities beneath Thailand and Malay Peninsula by using teleseismic waveform analysis from 7 earthquakes in Prachuap Khiri Khan, Thailand. The seismic waveform studies on phase arrivals of P–wave and S-wave data retrieve from 2 broadband seismic stations, 1 CHTO station (Chiang Mai–Thailand) and 2 BTDF station (Singapore), are analysed in this paper. Obviously, the crustal seismic velocities from each stations were difference, with Vp (7.683–7.892 km/s) and Vs (4.275–4.403 km/s) propagations in the southern path (Malay Peninsula) are greater than Vp (7.556–7.827 km/s) and Vs (4.220–4.376 km/s) propagates in the northern path. The results show that to the corresponding with differ in earth’s crust density, the continental crust is less dense than the oceanic crust, and these data available for crustal seismic velocity for these region.
An array of coupled nonlinear oscillators as a model for amplitude variations in intermodulation distortions from the auditory system
Authors: Prawanta E , Kitana N , Leelasiriwong W , Roongthumskul Y 
Published: December 2019

Abstract
The response of a nonlinear oscillator driven by two or more forces displays several frequency components corresponding to the linear combinations of the driving frequencies, known as intermodulation distortions (IMDs). The auditory system of all classes of vertebrates produces strong IMDs in the presence of sounds of two tones. This phenomenon is attributed to the nonlinearity of the biological acoustic sensors within the inner ear. In this work, we developed a numerical model to investigate the total IMDs generated by a chain of coupled nonlinear oscillators. Total nonlinear distortions exhibited variations in amplitudes with respect to the stimulus frequency. The variation profile was sensitive to the magnitude of the driving forces and the difference in the two driving frequencies. We found that the arrangement of the oscillators’ characteristic frequencies was necessary for the variations in total IMD level. Results from the numerical model agreed with measurements of IMDs from Chinese edible frog (Hoplobatrachus Rugulosus), whose inner ear is constituted by arrays of acoustic receptors with progressively increasing natural frequencies. In response to sounds of two tones, IMDs produced by the inner ear of Chinese edible frog exhibited variations in amplitudes with respect to the driving frequencies. The third-order distortion level displayed several peaks at high stimulating sound pressure level, and at large differences between the stimulus frequencies. Our findings suggest that an array of coupled nonlinear oscillator can serve as a simple model for the generation of nonlinear distortions by the inner ear.
Photon signal from non-interacting scalar dark matter annihilation
Authors: Sukrakarn Supalert , Robkob Udom 
Published: December 2019

Abstract
One proposal to search for Dark Matter is to look for photon signals which originates from DM annihilation. This is usually referred to as indirect detection experiment. In the case of Non-Interacting Scalar Dark Matter, there are no electromagnetic, strong, and weak interactions. Thus, the DM only interacts gravitationally. In our model, we determine the NISDM annihilation into a virtual graviton which subsequently creates a pair of Higgs bosons. The Higgs boson then suddenly decays into two photons. The line of sight integral is considered as a signifcant efect of the DM halos density profle. The total cross-section, thermally averaged cross-section and photon signal are fnally calculated and illustrated.
Concentration measurement of chromium passivation solutions by an optical method
Authors: Sibsiri K , Suwanchaituch T , Meechan W , Luengviriya C 
Published: December 2019

Abstract
Chromium passivation solutions are widely used in the last step of plating process for improving metal surfaces. The appearance as well as corrosion resistance of the threated surface depend on the thickness of chrome layer which is controlled by many factors including the concentration of the solution. In this research, we study the relation of the light absorption and the concentrations of a chromium passivation solution. We prepare the solutions with five different concentrations and measure their absorbance by using an ultraviolet-visible spectrometer. The absorption spectrum non-monotonously changes with the wavelength of the incident light. However, the absorbance always linearly increases with the concentration at all wavelengths. We construct several calibration equations at different wavelengths and test them by using solution samples with other concentrations. The results show that the concentration of chromium passivation solution should be measured at wavelengths in the range of 420-700 nm because the errors are less than 5%.
A sky survey of neutral Hydrogen at 21 cm using NARIT 4.5m small radio telescope
Authors: Tisawech K , Tummuangpak P , Asanok K , Jaroenjittichai P 
Published: December 2019

Abstract
We surveyed the neutral hydrogen (HI) at 21 cm by using the 4.5m Thai Small Radio Telescope (SRT) of the National Research Institute of Thailand (NARIT) during January–March 2019. The main aim of this project is for doing the distribution maps of HI in our Galaxy which will be shown in terms of the radial velocities and the HI positions in the galactic coordinate. The selected positions are mainly along the galactic plane (above or under the plane) within 21 degrees. The galactic longitudes are during 0 to 258 degrees. According to studies, the spectrum mode of NARIT-SRT receiver is recorded and divided into 400 channels with the velocity resolution ∼1.05 kms-1. Full width at half maximum (FWHM) of the NARIT - SRT is about 3-4 degrees. Its system temperature is 147.5 ± 5.1 K. The distribution map of HI clouds at 21 cm with the NARIT-SRT is presented in term of the radial velocity (vr
) in the range of [0: +220] kms-1 and the column density of HI down to the level 1019 per cm-2. Our results are in good agreement with theoretical values and international database.
Photoluminescence of ZnO nanorods prepared by hydrothermal method
Authors: Thongpool V , Phunpueok A , Jaiyen S 
Published: December 2019

Abstract
In this research, the effects of calcination temperature and reaction time on the photoluminescent properties of ZnO nanorods prepared by hydrothermal processes were studied. Morphology, crystalline structure and photoluminescent properties of the prepared samples were analyzed by scanning electron microscope (SEM), X-ray diffractrometer (XRD) and fluorescent spectrophotometer. The study found that a reaction time of 5 hours on a glass slide and calcination at 500°C was the best preparation condition. The prepared ZnO nanorods were aligned without direction and distributed throughout the substrate. The average diameter of the prepared ZnO nanorods was 91.96 ± 21.16 nm. The prepared ZnO nanorods comprised a hexagonal crystalline structure with an emission peak in the UV range.
Classifying Maser features with Fortran and shell script for proper motion study of Water masers in W49N
Authors: Phetra M , Asanok K , Hirota T , Kramer B H , Sugiyama K , Nuntiyakul W 
Published: December 2019

Abstract
The 22-GHz Water masers in the W49N star-forming region are one of the richest and most luminous sources in our Galaxy, at the distance of 11.11 kpc. Very Long Baseline Interferometric (VLBI) observations allow us to study both physics of these masers and the star formation process. However, observational results often show numerous (up to several thousand) maser spots, making manual data analysis time-consuming. Therefore, we have developed a new software with simple computer codes to classify maser features in this source observed with KaVA by Asanok et al. (in preparation). Fortran computer language and bash shell script are developed and tested by applying to 3 epochs of data sets. The peak flux and relative position of maser spots are measured using AIPS software. The analysis procedures are as follows: (1) the data are extracted to the package in table format (peak flux and x-y relative positions), (2) maser spots are counted under specified rules, (3) the maser feature is calculated by using flux-weighted mean method, and (4) the output results are compared with those obtained from the conventional method. Preliminary results show that these newly developed codes are able to automatically identify up to 30% of those maser features found by the conventional method in a consistent manner. Therefore, further improvement and development are needed for future application.
Physical properties distribution of galaxy population in Abell 2142 cluster
Authors: Poopakun Kledsai , Kriwattanawong Wichean 
Published: December 2019

Abstract
In this work, we investigate the physical properties of galaxies in Abell 2142 using photometric and spectroscopic data from the Sloan Digital Sky Survey (SDSS). The sample was selected by two criteria: redshift of 0.0781 ⩽ z ⩽ 0.1038 and the location within a radius of 100 arcminutes from the cluster centre. We found that the sample distributes into 2 groups, a foreground filament galaxies with z ⩽ 0.085 and the cluster members with z > 0.085. The relation between apparent magnitude in g filter band and u – z colour suggests that we can use the u – z equals 3.2 as a criterion to separate galaxies into blue (u – z ⩽ 3.2) and red (u – z > 3.2) sequence galaxies. Moreover, blue sequence galaxies have higher value of equivalent width of hydrogen alpha corresponding to higher star forming activity than red sequence galaxies. The nearby filament contains higher fraction of star forming galaxies (65%) than the cluster Abell 2142 galaxy members (46%). This could be due to difference of the environmental effect.