bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of electron energy spread effects on the intracavity MIR-FEL power at the PBP-CMU electron linac laboratory
Authors: Sukara S , Ohgaki H , Rimjaem S 
Published: January 2021

Abstract
At the PBP-CMU Electron Linac Laboratory, the existing linear accelerator system is under developing to produce electron beams with suitable properties for generation of oscillator mid-infrared free-electron laser (MIR-FEL) and super-radiant terahertz (THz) undulator radiation. This work focuses on the simulation of the oscillator MIR-FEL with expected electron beam energy of 20 – 25 MeV to evaluate the required electron beam parameters. To achieve FEL saturation, the single-pass FEL simulation using the code GENESIS 1.3 was performed to estimate the laser wavelength, FEL gain and electron macro-pulse duration. In the simulation, electron beams with energy spread of 0, 0.5 and 1.0 %, and the electron peak current of 25 and 50 A were considered. As a result, the electron beam with energy of 20 – 25 MeV can produce the FEL wavelengths of 13.5 – 21.2 µm using a 1.6-m undulator with maximum undulator parameter of 1.07. The largest FEL gain is 216% when using electron beam energy and peak current of 20 ± 0% MeV and 50 A, which requires the electron macro-pulse duration of 1.6 µs to saturate FEL. Due to the possible macro-pulse duration at our facility of 6 µs, the operation of electron beam with energy spread of 0.5% and peak current of higher than 25 A is required to saturate FEL. Results from this single-pass simulation can be used as a based information for further practical consideration with multi-pass simulation.
Preliminary analysis of ice Cherenkov detector operation during a latitude survey
Authors: Tangjai Y , Pagwhan A , Nuntiyakul W , Ruffolo D , Bieber J W , Clem J , Mangeard P S , Pyle R , Sáiz A 
Published: January 2021

Abstract
IceTop, the surface component of IceCube Neutrino Observatory at the South Pole, studies cosmic ray air showers with an array of ice Cherenkov detectors typically referred to as “IceTop Tanks.” In November 2009, collaborators from the University of Delaware, UW River Falls, and Uppsala University loaded an insulated shipping container containing an IceTop Tank on the icebreaker Oden which traversed the Atlantic Ocean from Helsingborg, Sweden to McMurdo, Antarctica, and return. Over an approximately 6-month interval, Oden carried the IceTop Tank through a wide range of geomagnetic cut-offs. The data obtained will allow the energy dependent effective area (yield function) to be determined using the Earth as a magnet spectrometer. The ultimate goal of the project is to calibrate the IceTop Tanks to study cosmic rays in the GeV primary energy range. We will report preliminary results for determining the yield functions.
Preliminary analysis of neutron time-delay histograms from Changvan latitude surveys
Authors: Yakum P , Jiang P , Chuanraksasat P , Nuntiyakul W , Ruffolo D , Sáiz A , Banglieng C , Evenson P , Munakata K , Madsen J , Soonthorntham B , Komonjinda S , Macatangay R 
Published: January 2021

AbstractThe name “Changvan” is given to a transportable neutron monitor, modernized by researchers in Thailand and housed inside a standard-size shipping container. It contains three neutron-sensitive proportional counters, which contain enriched10BF3gas, to detect cosmic ray showers. Primary cosmic rays are high-energy particles arriving from outer space. By colliding with atoms in the atmosphere, they produce a shower of sub-atomic particles, called secondary particles. Some particles can reach the Earth’s surface, including neutrons. The Changvan is designed to measure atmospheric neutrons during a latitude survey. The side counter tubes are ringed with lead producer to produce evaporation neutrons when secondary particles collide with it. The center counter lacks the lead producer but can receive neutrons from nearby counters. The reflector and moderator made from polyethylene thermalize the evaporation neutrons and protect against disturbance by external low-energy neutrons. In this work, we pursue methods to determine spectral changes in Galactic cosmic rays using data from the Changvan, avoiding the systematic inconsistencies of cross-station comparisons. We examine neutron time delay histograms from the three counter tubes, as recorded by specially designed readout electronics, where the time delay refers to the time interval between consecutive neutron detections in one counter. We perform a preliminary analysis of such histograms to measure the leader fraction (L) of neutrons that do not follow a previous neutron from the same primary cosmic ray. The electronic dead time will be considered in theLcalculation.
Short time flux variability of water masers in W49 N using KaVA data
Authors: Phetra M , Asanok K , Hirota T , Kramer B H , Sugiyama K , Nuntiyakul W 
Published: January 2021

Abstract
We investigated flux variability of 22 GHz water masers in W49 N, which have been observed for three epochs in the early year of 2017 using KaVA. We used angular resolution and Doppler velocity conditions to specify the identical maser features in each epoch. The flux variability of water masers was defined as the ratio of flux intensity varied by increasing more than five times of the first epoch and to be found as the features in all three epochs. We found three bright features with their weighted local standard of rest (LSR) velocities at -92.25±0.56, -19.28±0.26 and +64.81±0.32 km s−1. Two features were located in the blueshifted and a feature in the redshifted outflows. To understand the environment of the W49 N star forming region, we, therefore, consider the distribution of water masers compared to other thermal molecular line emissions.
Empirical model of magnetic field line spreading in isotropic turbulence with varying mean field
Authors: Sonsrettee Wirin 
Published: January 2021

Abstract
In many astrophysical phenomena, understanding the diffusion of the magnetic eld line random walk (FLRW) is central to understand cosmic ray transport. In 3D uctuations, the behavior of the FLRW can be characterized by the Kubo number R = (b/B
0)(l

⫽⃥
/l

∧
) [1], where the parameters b and B
0 are the rms magnetic uctuation and the large-scale mean eld, respectively. The parameters l

∥
and l

∧
are coherence scales parallel and perpendicular to B
0, respectively. For isotropic turbulence, in which l

∥
= l

∧
, Sonsrettee et al. [2] found that Corrsin-based theories can be applied to study the FLRW’s behavior for a whole range of R by varying b/B
0. Sonsrettee et al. [2] used Corrsin-based theory with three models of eld line spreading to examine the R-scaling of the asymptotic diffusion coefficients for the FLRW. The models are the diffusive decorrelation (DD) model [3{5], the random ballistic decorrelation (RBD) model [6], and the ordinary differential equation (ODE) model [7]. To improve the theory of the FLRW in isotropic turbulence with B
0 = 0, Sonsrettee [8] proposed the empirical (EMP) model of magnetic eld line spreading to determine the asymptotic diffusion coefficients. Benchmarked against the previous models, the EMP model is the best model to predict computer simulation results (with ≤ 0:9% error). In this work, we extend the previous works [2, 8] by formulating the EMP model to explore the R scaling FLRW behavior in isotropic magnetic turbulence by varying B
0. In the limit of very low R, we obtain the the closed-form solution of the FLRW for the EMP model. In order to develop the closed-form solution at any R, we employ the Padé approximants to the EMP model. The EMP model predicts that, with increasing R, the FLRW behavior transits from quasilinear diffusion to Bohm diffusion. This work shows that the theoretical results of the EMP model match the computer simulation results for the FLRW in Kolmogorov turbulence better than the other models significantly.
Preliminary analysis of the Changvan neutron monitor operation in latitude surveys during 2019-2020
Authors: Khamphakdee S , Jiang P , Chuanraksasat P , Nuntiyakul W , Ruffolo D , Sáiz A , Evenson P , Munakata K , Madsen J , Soonthorntham B , Komonjinda S , Macatangay R 
Published: January 2021

AbstractWithin our solar system, space weather is influenced by the solar wind and the interplanetary magnetic field carried by the solar wind plasma. Severe solar storms can expose people to increased radiation levels, shut down electrical systems, and interfere with radio signals. Space weather probably affects the weather and climate on our planet, but we do not yet have a precise understanding of the influence. Some aspects of space weather can be monitored at ground level with a detector, such as a “neutron monitor,” that measures cosmic rays from outer space. We have developed a portable “Changvan” neutron monitor to investigate the energy spectrum of cosmic rays and its solar modulation, i.e., variations over the typically 11-year sunspot cycle. The Changvan monitor located inside the insulated shipping container comprises three proportional counters in the standard-design neutron monitors, but the central counter is deficient in the lead producer. This monitor records counting rates during passage through a range of geomagnetic latitudes, which this technique is called “latitude survey.” The ultimate goal of the latitude surveys is to help accurately interpret data from every neutron monitor in a space environment that is always changing. In this work, we show a preliminary analysis of Changvan monitor data collected from two latitude surveys during 2019-2020 on the Chinese icebreaker MV Xue Long from Shanghai, China to Zhongshan station, Antarctica and back. A strong anti-correlation can be observed between the Changvan monitor count rate and barometric pressure.
Tracking origins of gamma rays in the Milky Way galaxy by a Fermi-LAT all sky map
Authors: Ngernphat Karn , Saowanit Grit , Wechakama Maneenate 
Published: January 2021

Abstract
We have used gamma ray data of an all sky map from Fermi-LAT to estimate a mathematical model of emission coefficient to find the origins of gamma rays in the Milky Way galaxy. The emission coefficient is defined for the first time by spherical and cylindrical distributions which are explained by dark matter annihilation and astrophysical sources, respectively. We have provided parameter values from our fitting by least chi-square method. Our parameters for cylindrical distribution are compatible with previous studies, except the thickness of the galactic disk which 10 times bigger than the previous studies since they have set the value of the thickness as 0.100 kpc for a thin cylindrical disk of the Milky Way galaxy but we have considered the whole range of latitude for the all sky map. It indicates that our model has provided a thicker galactic disk than the others. In addition, we have provided the parameter values of spherical distribution which we can apply to constrain properties of dark matter particles in the Milky Way galaxy for future studies.
Effect comparison of dark matter annihilation pressure to NFW and pseudo-isothermal profiles of low surface brightness galaxies
Authors: Duangchan Chaimongkol , Sinpaiboon Wonchana , Chantaso Nakarin , Haethaisong Waeowan , Wechakama Maneenate 
Published: January 2021

Abstract
We have studied the effect of gas pressure created by electrons and positrons produced from dark matter annihilation for low surface brightness (LSB) galaxies. We have applied 4 different gas and stellar disk models and 2 different dark matter density profiles, i.e. Navarro Frenk and White (NFW) and pseudo-isothermal, to each galaxy. We assume that electrons and positrons are produced from dark matter annihilation and they can lose their energy to photons and the interstellar medium in the galaxies by different loss processes. The pressure of electron and positron gas is a function of the electron-positron spectrum obtained from a diffusion-loss equation which included source term, diffusion coefficient and loss rate. We have added the pressure gradient to the rotation curves of LSB galaxies. We have compared the results with observations by using reduced chi-square. We have found that the pressure from dark matter annihilation provided better fits for several galaxies for NFW profiles but it doesn’t play any role for pseudo-isothermal profiles. From these results, we can use NFW profile with pressure from dark matter annihilation to improve the situation of cusp-core problems and to constrain properties of dark matter particles by rotation curves of LSB galaxies for future studies.
Role of wavefront and velocity distribution with magnetic lens on matter-wave diffraction in near-field regime
Authors: Wongrach K , Janpoon J , Deachapunya S , Srisuphaphon S 
Published: January 2021

Abstract
Near-field diffraction has been widely studied and applied in many research fields including optics, quantum mechanics and sensor technology. High accuracy sensors, for instance, have been developed based on the Talbot effect, i.e., the self-imaging effect, due to the high sensitivity of the near-field diffraction pattern. Since the visibility of the diffraction pattern depends intensively on velocity distribution and wavefront of the incoming wave, the Talbot-Lau effect is generally used to improve the spatial coherence of the incident wave and hence a better fringe contrast. This research aims to investigate the influences of the wavefront spreading out radially involving the Gaussian velocity distribution on the diffraction pattern of a matter-wave which are key points in design optimization and development of tools for improving fringe quality. The probability density to find the particles in the Talbot-Lau interference pattern can be obtained by employing Feynman path integrals. The theoretical simulation results show that the alteration of wavefront leads to changes in fringe contrast and the width of fringe peaks, whereas the velocity distribution affects only the fringe visibility.
Impact of rainfall on the transmission of leptospirosis in Si Sa Ket, Thailand
Authors: Wichapeng S , Chadsuthi S , Modchang C 
Published: January 2021

Abstract
Leptospirosis is a zoonotic disease found worldwide, but especially in tropical and sub-tropical countries. In Thailand during the rainy season, agricultural and livestock workers are the main occupational risk groups, who are likely to be in contact with contaminated environments. In this study, we aim to examine the impact of rainfall on the transmission of leptospirosis using a stochastic cellular automata model in Si Sa Ket, Thailand, which had the highest number of reported cases from 2014 to 2018. Two bi-dimensional square lattices are created to represent human and contaminated environmental lattices. The reported cases are used to fit in the simulation results by varying transmission probability. The transmission probability depends on sinusoidal function and the rainfall index, the results of which are compared. This study highlighted the way that seasonal rainfall contributed to the transmission dynamics of leptospirosis. The total epidemic size, which is the sum of the overtime cases, was investigated to find the critical transmission probability from the endemic to the epidemic state. Further study of other factors such as flooding and temperature, should be investigated for a better understanding of how the transmission of leptospirosis affects the environment.
Venipuncture training assists using electrical sensors in a rubber arm system
Authors: Saengpayab Y , Kongsri W , Chongsereecharoen E , Pratummasoot N , Akkarapattanapong V , Jarintanan F 
Published: January 2021

Abstract
The main purpose of the present study was to implement a sensor system to help improving the venipuncture accuracy for medical technology students using a rubber arm system. The rubber arm simulated human arm having veins with a pump circulated fluid inside. The fluid represented human blood which is usually withdrawn at three areas of vein in the arms, i.e., median cephalic, median basilic, and median cubital veins. The venipuncture sensing system consists of the electrical sensors connected to the rubber arm, a needle and a control box. The arm sensor was designed to detect electric quantities derived as the result of different resistances of needle tip in different materials. Three testers performed ten venipuncture tests at each at the three locations by using the sensor system. During the test, the numbers of venipuncture and various types of venipuncture output were collected by the sensor. Based on the results, the accuracy of the venipuncture was determined. It was found that the average accuracy was 76±10%. Moreover, the training effectiveness of the system was evaluated by divided the accuracy results into two parts i.e., the first half and the second half of the tests. Accuracy comparisons was made between these parts. It was found that the accuracy was improved at all three areas along with the reduced through venipuncture percentage. This research provided an optional possibility of using a venipuncture sensor for medical technology students.
Effects of Mg substitution on electronic properties of CaF2
Authors: Chintananon N , Tsuppayakorn-aek P , Sukmas W , Bovornratanaraks T , Pinsook U 
Published: January 2021

Abstract
We investigated the phase transitions of CaF2, using the state-of-the-art density functional theory. The calculations show that the fluorite structure, with the space group

Fm

3

¯

m

, transforms into the cotunnite structure, with the space group Pnma, at 8 GPa. The electronic band structure of the Pnma-CaF2 structure can be classified as an insulating phase with a wide bandgap, and the bandgap decreases under pressure above 70 GPa. Also, we proposed the Ca/Mg-substituted fluorides MgxCa1-xF2, using the cluster expansion technique which is commonly used to study alloys. We found that the Mg0.25Ca0.75F2 compound with a Pm structure is stable at 70 GPa. The results of the electronic band structure reveal that the substitution of Mg enhances the bandgaps of the Mg0.25Ca0.75F2 compounds under pressure above 70 GPa, compared with those of CaF2.
Structural and electronic properties of 2D chalcogenides
Authors: Muhammad Ibrahim Yahaya 
Published: January 2021

Abstract
Two-dimensional (2D) materials and their heterostructures are useful in electronic applications, especially with the drive towards more and more miniaturization. Using first-principles calculations, we study the structural and electronic properties of some transition metal dichalcogenides and diselenides (MoS2, MoSe2, WS2, WSe2). Our studies were based on density functional theory (DFT) as implemented in the Quantum ESPRESSO package. 2D layered materials present a huge challenge for DFT as a result of interlayer van der Waals (vdW) interaction which is absent from the typical DFT exchange-correlation functional. In order to account for the van der Waals interactions between layers, we applied the semi-empirical DFT-D2 method of Grimme and the revised Vydrov-Van Voorhis non-local correlation functional (rVV10). We show that the two approaches give similar structural properties. We also found that the size of the electronic band gap of these structures changes with respect to the number of layers stacked.
A GPU implementation of least-squares reverse time migration
Authors: Sombutsirinun Phudit , Boonyasiriwat Chaiwoot 
Published: January 2021

Abstract
Least-squares reverse time migration (LSRTM) is a seismic imaging method that can provide higher-resolution image of the subsurface structures compared to other methods. However, LSRTM is computationally expensive. To reduce the computational time of LSRTM, GPU can be utilized. This leads to the objective of this work which is to develop a GPU implementation of LSRTM. In this work, the two-dimensional first-order acoustic wave equations are solved using the second-order finite difference on a staggered grid and a perfectly matched layer is used as an absorbing boundary condition. The adjoint-state method is used to compute the gradient of the objective function. A linear conjugate gradient method is used to minimize the objective function. Both forward- and backward-propagation of wavefields using the finite-difference method are performed on a single GPU using the NVIDIA CUDA library. For a verification purpose, the GPU program of LSRTM was applied to a synthetic data set generated from the Marmousi model. Numerical results show that LSRTM can provide an image with a higher resolution of subsurface structure compared to a conventional RTM image. For a computational cost issue, the GPU-version of LSRTM is significantly faster than the serial CPU-version of LSRTM.
Comparison of solar spectrum from measurements and that from radiative transfer model under overcast sky condition
Authors: Tohsing K , Peengam S , Janjai S 
Published: January 2021

Abstract
The solar spectrum under overcast sky condition is of importance for determining the optical properties of cloud by using a radiative transfer model. In this study, solar spectrum under overcast sky condition was measured by employing a spectroradiometer (Instrument System, model SP-320) at Nakhon Pathom station (13.82 ˚N, 100.04 ˚E), Thailand. The wavelength range of the measurements is 220-2400 nm, with the resolution of 1 nm in the wavelength range: 220-1700 nm and the resolution of 20 nm in the wavelength range: 1700-2400 nm. The overcast sky condition is determined by using the images of the sky taken by an automatic sky camera. Fifteen datasets of the solar spectrum were compared with those calculated by a radiative transfer model called “LIBRADTRAN”. The input data of the radiative transfer model were obtained from both measurements and literature. As part of the input data, aerosol optical properties were obtained from an AERONET sunphotometer, total ozone column from OMI/AURA satellite and cloud base height from a ceilometer. It was found that the solar spectrum from the measurements and that from the calculation are in reasonable agreement, with the discrepancy in terms of root mean square error (RMSE) of 0.043 W·m−2·nm−1. This comparison indicates that this radiative transfer model is accurate enough for use in determining the optical properties of clouds.
An implementation of a recurrent neural network for 1D acoustic waveform inversion
Authors: Pukhamwong P , Boonyasiriwat C 
Published: January 2021

Abstract
Recurrent neural network (RNN) is a class of artificial neural networks widely used to model a temporal dynamic system. Recently, recurrent neural networks have been developed for acoustic waveform modelling in 1D and 2D bounded domains. Since the trainable parameters of the networks are the acoustic wave velocity, the process of network training is equivalent to solving an inverse problem of acoustic waveform inversion. In this work, we extend the previously proposed RNNs for acoustic waveform modelling/inversion in 1D unbounded domains by incorporating perfectly matched layers (PML) into the RNN cell. The proposed RNN architecture was implemented using Tensor Flow and has been successfully tested on a 1D synthetic data set. The results show that we have successfully implemented PML to RNN base acoustic full waveform inversion.