bluuebunny/crossref_metadata_2025 huggingface dataset:
A Search for Solar Axions and Anomalous Neutrino Magnetic Moment with the Complete PandaX-II Data*
Authors: Zhou Xiaopeng , Zeng Xinning , Ning Xuyang , Abdukerim Abdusalam , Chen Wei , Chen Xun , Chen Yunhua , Cheng Chen , Cui Xiangyi , Fan Yingjie , Fang Deqing , Fu Changbo , Fu Mengting , Geng Lisheng , Giboni Karl , Gu Linhui , Guo Xuyuan , Han Ke , He Changda , Huang Di , Huang Yan , Huang Yanlin , Huang Zhou , Ji Xiangdong , Ju Yonglin , Li Shuaijie , Liu Huaxuan , Liu Jianglai , Lu Xiaoying , Ma Wenbo , Ma Yugang , Mao Yajun , Meng Yue , Ni Kaixiang , Ning Jinhua , Ren Xiangxiang , Shang Changsong , Shen Guofang , Si Lin , Tan Andi , Wang Anqing , Wang Hongwei , Wang Meng , Wang Qiuhong , Wang Siguang , Wang Wei , Wang Xiuli , Wang Zhou , Wu Mengmeng , Wu Shiyong , Wu Weihao , Xia Jingkai , Xiao Mengjiao , Xie Pengwei , Yan Binbin , Yang Jijun , Yang Yong , Yu Chunxu , Yuan Jumin , Yuan Ying , Zhang Dan , Zhang Tao , Zhao Li , Zheng Qibin , Zhou Jifang , Zhou Ning
Published: January 2021

We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-II, in light of the recent event excess reported by XENON1T. The data correspond to a total exposure of 100.7 ton⋅day with liquid xenon. With robust estimates of the dominant background spectra, we perform sensitive searches on solar axions and neutrinos with enhanced magnetic moment. It is found that the axion-electron coupling g
Ae < 4.6 × 10–12 for an axion mass less than 0.1 keV/c
2 and the neutrino magnetic moment μν
< 4.9 × 10–11
μ
B at 90 % confidence level. The observed excess from XENON1T is within our experimental constraints.
Photonic Thermal Rectification with Composite Metamaterials
Authors: Toyin Ogundare Rasheed , Ge Wenxuan , Gao Lei
Published: January 2021

We demonstrate strong photonic thermal rectification effect between polar dielectrics plate and the composite metamaterials containing nonspherical polar dielectric nanoparticles with small volume fractions. Thermal rectification efficiency is found to be adjusted by the volume fractions and the nanoparticles' shape, and it can be as large as 80% when the polar dielectric nanoparticles are spherical in shape and are in the dilute limit with the volume fraction f = 0.01. Physically, there exists strong electromagnetic coupling between the surface phonon polariton mode of polar dielectrics plate and the localized surface phonon polariton mode around polar dielectric nanoparticles. The results provide alternative new freedom for regulating energy flow and heat rectification efficiency in the near field, and may be helpful for design of multiparameter adjustable thermal diodes.
Enhancement of hydrogen peroxide production from an atmospheric pressure argon plasma jet and implications to the antibacterial activity of plasma activated water
Authors: Ghimire Bhagirath , Szili Endre J , Patenall Bethany L , Lamichhane Pradeep , Gaur Nishtha , Robson Alexander J , Trivedi Dhruv , Thet Naing T , Jenkins A Toby A , Choi Eun Ha , Short Robert D
Published: January 2021

We explore how to configure an argon atmospheric-pressure plasma jet for enhancing its production of hydrogen peroxide (H2O2) in deionised water (DIW). The plasma jet consists of a quartz tube of 1.5 mm inner diameter and 3 mm outer diameter, with an upstream internal needle electrode (within the tube) and a downstream external cylindrical electrode (surrounding the tube). The plasma is operated by purging argon through the glass tube and applying a sinusoidal AC voltage to the internal needle electrode at 10 kV (peak–peak) with a frequency of 23.5 kHz. We study how the following operational parameters influence the production rate of H2O2 in water: tube length, inter-electrode separation distance, distance of the ground electrode from the tube orifice, distance between tube orifice and the DIW, argon flow rate and treatment time. By examining the electrical and optical properties of the plasma jet, we determine how the above operational parameters influence the major plasma processes that promote H2O2 generation through electron-induced dissociation reactions and UV photolysis within the plasma core and in the plasma afterglow; but with a caveat being that these processes are highly dependent on the water vapour content from the argon gas supply and ambient environment. We then demonstrate how the synergistic action between H2O2 and other plasma generated molecules at a plasma induced low pH in the DIW is highly effective at decontaminating common wound pathogens Gram-positive Staphylococus aureus and Gram-negative Pseudomonas aeruginosa. The information presented in this study is relevant in the design of medical plasma devices where production of plasma reactive species such as H2O2 at physiologically useful concentrations is needed to help realise the full clinical potential of the technology.
Order–disorder transitions in a minimal model of active elasticity
Authors: Lin Guozheng , Han Zhangang , Huepe Cristián
Published: January 2021

We introduce a new minimal model for self-propelled agents that attract, repel, and align to their neighbors through elastic interactions. This model has a simple mechanical realization and provides an approximate description of real-world systems ranging from active cell membranes to robotic or animal groups with predictive capabilities. The agents are connected to their neighbors by linear springs attached at a distance R in front of their centers of rotation. For small R, the elastic interactions mainly produce attraction-repulsion forces between agents; for large R, they mainly produce alignment. We show that the agents self-organize into collective motion through an order–disorder noise-induced transition that is discontinuous for small R and continuous for large R in finite-size systems. In large-scale systems, only the discontinuous transition will survive, as long-range order decays for intermediate noise values. This is consistent with previous results where collective motion is driven either by attraction–repulsion or by alignment forces. For large R values and different parameter settings, the system displays a novel transition to a state of quenched disorder. In this regime, lines of opposing forces are formed that separate domains with different orientations and are stabilized by noise, producing locally ordered yet globally disordered quenched states.
Optimization of coupling and global collapse in diffusively coupled socio-ecological resource exploitation networks
Authors: Holstein Tanja , Wiedermann Marc , Kurths Jürgen
Published: January 2021

Single- and multi-layer complex networks have been proven as a powerful tool to study the dynamics within social, technological, or natural systems. An often observed common goal is to optimize these systems for specific purposes by minimizing certain costs while maximizing a desired output. Acknowledging that especially real-world systems from the coupled socio-ecological realm are highly intertwined this work exemplifies that in such systems the optimization of a certain subsystem, e.g. to increase the resilience against external pressure in an ecological network, may unexpectedly diminish the stability of the whole coupled system. For this purpose we utilize an adaptation of a previously proposed conceptual bi-layer network model composed of an ecological network of diffusively coupled resources co-evolving with a social network of interacting agents that harvest these resources and learn each other’s strategies depending on individual success. We derive an optimal coupling strength that prevents collapse in as many resources as possible if one assumes that the agents’ strategies remain constant over time. We then show that if agents socially learn and adapt strategies according to their neighbors’ success, this optimal coupling strength is revealed to be a critical parameter above which the probability for a global collapse in terms of irreversibly depleted resources is high—an effect that we denote the tragedy of the optimizer. We thus find that measures which stabilize the dynamics within a certain part of a larger co-evolutionary system may unexpectedly cause the emergence of novel undesired globally stable states. Our results therefore underline the importance of holistic approaches for managing socio-ecological systems because stabilizing effects which focus on single subsystems may be counter-beneficial for the system as a whole.
Realistic and dark stellar models via embedding approach in the Rastall gravity
Authors: Mustafa G , Hussain Ibrar , Shamir M Farasat , Tie-Cheng Xia
Published: January 2021

This study explores the Rastall theory of modified gravity for three different compact stars based on observational facts, by assuming the Karmarkar condition with an anisotropic fluid profile. We adopt an explicit

g

rr

metric potential element, which fulfills the important condition (Karmarkar condition). The new model permits to solve the differential equation for another metric component

g

tt

by exploiting the Karmarkar condition. Further, we present the interior solution in the allusion of the Schwarzchild interior comparable solution for Rastall theory, which is physically suitable. Moreover, we explore some physically essential attributes by using the masses and radii from observational data for three different stellar objects. It is perceived that the acquired results are physically considerable to the best degree of accuracy. All the physically essential parameters and properties are presented graphically, and these graphs display the calculated solutions that are feasible for three different stellar objects. It is noticed that the parameter c, appearing in the family of solutions that are satisfying the Karmarkar condition for the anisotropic matter, has some vital role for these solutions. Furthermore, we also explore dark stars by taking positive values of the Rastall parameter. We observe that our results are in agrement with in the framework of the Rastall gravity.
Sparse Box-fitting Least Squares
Authors: Panahi Aviad , Zucker Shay
Published: January 2021

We present a new implementation of the commonly used Box-fitting Least Squares (BLS) algorithm, for the detection of transiting exoplanets in photometric data. Unlike BLS, our new implementation—Sparse BLS, does not use binning of the data into phase bins, nor does it use any kind of phase grid. Thus, its detection efficiency does not depend on the transit phase, and is therefore slightly better than that of BLS. For sparse data, it is also significantly faster than BLS. It is therefore perfectly suitable for large photometric surveys producing unevenly-sampled sparse light curves, such as Gaia.
Curvature-induced noncommutativity of two different components of momentum for a particle on a hypersurface
Authors: Li Z , Yang X , Liu Q H
Published: January 2021

As a nonrelativistic particle constrained to remain on an (N − 1)-dimensional ((N ≥ 2)) hypersurface embedded in an N-dimensional Euclidean space, two different components pi
and p

j
(i, j = 1, 2, 3,… N) of the Cartesian momentum of the particle are not mutually commutative, and explicitly commutation relations

[

p

ˆ

i

,

p

ˆ

j

]

≠
0

depend on products of positions and momenta in uncontrollable ways. The generalized Dupin indicatrix of the hypersurface, a local analysis technique, is utilized to explore the dependence of the noncommutativity on the curvatures around a local point of the hypersurface. The first finding is that the noncommutativity can be grouped into two categories; one is the product of a sectional curvature and the angular momentum, and another is the product of a principal curvature and the momentum. The second finding is that, for a small circle lying a tangential plane covering the local point, the noncommutativity leads to a rotation operator and the amount of the rotation is an angle anholonomy; and along each of the normal sectional curves centering the given point the noncommutativity leads to a translation plus an additional rotation and the amount of the rotation is one half of the tangential angle change of the arc.
Pure annihilation decays of B

s

0 → a
0
+
a
0
− and B

d

0 →

K0*+

K0*−

in the PQCD approach
Authors: Chen Yutong , Jiang Zewen , Liu Xin
Published: January 2021

We study the CP-averaged branching fractions and the CP-violating asymmetries in the pure annihilation decays of

B

s

0

→

a

0

+

a

0

−

and

B

d

0

→

K

0

*
+

K

0

*
−

, where

a

0

[

K

0

*

]

denotes the scalar a
0(980) and a
0(1450) [

K

0

*

(
800
)
(
or

κ
)

and

K

0

*

(
1430
)

], with the perturbative QCD factorization approach under the assumption of two-quark structure for the a
0 and

K

0

*

states. The numerical results show that the branching ratios of the

B

d

0

→

K

0

*
+

K

0

*
−

decays are in the order of 10−6, while the decay rates of the

B

s

0

→

a

0

+

a

0

−

modes are in the order of 10−5. In light of the measured modes with the same quark components in the pseudoscalar sector, namely,

B

d

0

→

K

+

K

−

and

B

s

0

→

π

+

π

−

, the predictions for the considered decay modes in this work are expected to be measured at the Large Hadron Collider beauty and/or Belle-II experiments in the (near) future. Meanwhile, it is of great interest to find that the twist-3 distribution amplitudes ϕ

S
and ϕ

T
with inclusion of the Gegenbauer polynomials for the scalar a
0(1450) and

K

0

*

(
1430
)

states in scenario 2 contribute slightly to the branching ratios while significantly to the CP violations in the

B

d

0

→

K

0

*

1430

+

K

0

*

1430

−

and

B

s

0

→

a

0

1450

+

a

0

1450

−

decays, which indicates that, compared to the asymptotic ϕ

S
and ϕ

T
, these Gegenbauer polynomials could change the strong phases evidently in these pure annihilation decay channels. These predictions await for the future confirmation experimentally, which could further provide useful information to help explore the inner structure of the scalars and shed light on the annihilation decay mechanism.
Design and simulation of AlN-based vertical Schottky barrier diodes*
Authors: Su Chun-Xu , Wen Wei , Fei Wu-Xiong , Mao Wei , Chen Jia-Jie , Zhang Wei-Hang , Zhao Sheng-Lei , Zhang Jin-Cheng , Hao Yue
Published: January 2021

The key parameters of vertical AlN Schottky barrier diodes (SBDs) with variable drift layer thickness (DLT) and drift layer concentration (DLC) are investigated. The specific on-resistance (R
on,sp) decreased to 0.5 mΩ ⋅ cm2 and the breakdown voltage (V
BR) decreased from 3.4 kV to 1.1 kV by changing the DLC from 1015 cm−3 to 3 × 1016 cm−3. The V
BR increases from 1.5 kV to 3.4 kV and the R
on,sp also increases to 12.64 mΩ ⋅ cm2 by increasing DLT from 4-μm to 11-μm. The V
BR enhancement results from the increase of depletion region extension. The Baliga’s figure of merit (BFOM) of 3.8 GW/cm2 was obtained in the structure of 11-μm DLT and 1016 cm−3 DLC without FP. When DLT or DLC is variable, the consideration of the value of BFOM is essential. In this paper, we also present the vertical AlN SBD with a field plate (FP), which decreases the crowding of electric field in electrode edge. All the key parameters were optimized by simulating based on Silvaco-ATLAS.
Weak decays of doubly heavy baryons:

*
Authors: Li Run-Hui , Hou Juan-Juan , He Bei , Wang Ya-Ru
Published: January 2021

The discovery of

has inspired new interest in studying doubly heavy baryons. In this study, the weak decays of a doubly charmed baryon

to a light baryon

and a charm meson

(either a pseudoscalar or a vector one) are calculated. Following our previous work, we calculate the short distance contributions under the factorization hypothesis, whereas the long distance contributions are modeled as the final state interactions, which are calculated with the one particle exchange model. We find that the

decays' branching ratios are obviously larger, as they receive contributions of more polarization states. Among the decays that we investigate, the following have the largest branching fractions:

estimated with

fs;

and

with

fs; and

,

, and

with

fs. By comparing the decay widths of pure color commensurate channels with those of pure bow-tie ones, we find that the bow-tie mechanism plays an important role in charm decays.
Polarized light-by-light scattering at the CLIC induced by axion-like particles
Authors: İnan S.C. , Kisselev A.V.
Published: January 2021

In this study, light-by-light (LBL) scattering with initial polarized Compton backscattered photons at the CLIC, induced by axion-like particles (ALPs), is investigated. The total cross sections are calculated assuming CP-even coupling of the pseudoscalar ALP to photons. The 95% C.L. exclusion region for the ALP mass

and its coupling constant f is presented. The results are compared with CLIC bounds previously obtained for the unpolarized case. It is shown that the bounds on f for the polarized beams in the region

with collision energy of 3000 GeV and integrated luminosity of 4000 fb

are on average 1.5 times stronger than the bounds for the unpolarized beams. Moreover, our CLIC bounds are stronger than those for all current exclusion regions for

GeV. In particular, they are more restrictive than the limits that follow from the ALP-mediated LBL scattering at the LHC.
Probing tqZ anomalous couplings in the trilepton signal at the HL-LHC, HE-LHC, and FCC-hh *
Authors: Liu Yao-Bei , Moretti Stefano
Published: January 2021

We investigate the prospect of discovering the Flavour Changing Neutral Current (FCNC)

couplings via two production processes yielding trilepton signals: top quark pair production

with one top quark decaying to the Z boson and one light jet and the anomalous single top quark plus Z boson production process

. We study these channels at various successors of the Large Hadron Collider (LHC), i.e., the approved High-Luminosity LHC (HL-LHC) as well as the proposed High-Energy LHC (HE-LHC) and Future Circular Collider in hadron-hadron mode (FCC-hh). We perform a full simulation for the signals and the relevant Standard Model (SM) backgrounds and obtain limits on the Branching Ratios (BRs) of

, eventually yielding a trilepton final state through the decay modes

and

. The upper limits on these FCNC BRs at 95% Confidence Level (CL) are obtained at the HL-LHC with

TeV and 3 ab−1, at the HE-LHC with

TeV and 15 ab−1, and at the FCC-hh with

TeV and 30 ab−1.
Ion cyclotron resonance heating with shifted separatrix
Authors: Kolesnichenko Ya.I. , Patten H. , Lutsenko V.V. , Graves J.P. , Rudenko T.S. , Contributors JET
Published: January 2021

Ion cyclotron resonance heating, which we refer to as ICRH-SS, with the quasilinear (QL) separatrix (i.e., the separatrix in the space of QL routes of ion acceleration) located in the region of passing particles is studied. The aim of ICRH-SS is to minimize the fraction of trapped particles (particles with small longitudinal velocities) in the population of fast ions. The basic idea of ICRH-SS—shifting the separatrix to the region of passing particles—was advanced in the paper (Kolesnichenko et al 2017 Nuclear Fusion
57 066004). In this work, new features of ICRH-SS are revealed. The 3D QL routes of the particle acceleration and effects of Coulomb collisions are studied. A QL equation for distribution function of neutral beam injection (NBI) ions, which is convenient for analysis, is derived. Conditions for QL flux prevailing over collisional flux caused by pitch scattering are obtained. Numerical simulations using the SCENIC package are carried out for a JET plasma with NBI ions that are accelerated by RF field in the core region. A JET pulse designed as a demonstration of the so called ‘three ions’ scheme, which also complies with the criteria of ICRH-SS scheme, was selected. The numerical results show that in the considered example most accelerated ions have larger longitudinal velocities and fast particle orbits are passing during ICRH-SS, whereas, ‘conventional’ ICRH (defined as ICRH with the separatrix in the region of trapped particles) produces accelerated ions with banana orbits. Numerical results also show an increase in fast ion generation and core plasma heating performance for ICRH-SS as compared to the conventional ICRH.
A real-space renormalization-group calculation for the quantum

Z2

gauge theory on a square lattice
Authors: Paik Steve T
Published: January 2021

We revisit Fradkin and Raby’s real-space renormalization-group method to study the quantum

Z

2

gauge theory defined on links forming a two-dimensional square lattice. Following an old suggestion of theirs, a systematic perturbation expansion developed by Hirsch and Mazenko is used to improve the algorithm to second order in an intercell coupling, thereby incorporating the effects of discarded higher energy states. A careful derivation of gauge-invariant effective operators is presented in the Hamiltonian formalism. Renormalization group equations are analyzed near the nontrivial fixed point, reaffirming old work by Hirsch on the dual transverse field Ising model. In addition to recovering Hirsch’s previous findings, critical exponents for the scaling of the spatial correlation length and energy gap in the electric free (deconfined) phase are compared. Unfortunately, their agreement is poor. The leading singular behavior of the ground state energy density is examined near the critical point: we compute both a critical exponent and estimate a critical amplitude ratio.
Variational determination of the two-particle reduced density matrix within the doubly occupied configuration interaction space: exploiting translational and reflection invariance
Authors: Massaccesi G E , Rubio-García A , Capuzzi P , Ríos E , Oña O B , Dukelsky J , Lain L , Torre A , Alcoba D R
Published: January 2021

This work incorporates translational and reflection symmetry reductions to the variational determination of the two-particle reduced density matrix (2-RDM) corresponding to the ground state of N-particle systems, within the doubly occupied configuration interaction (DOCI) space. By exploiting these symmetries within this lower-bound variational methodology it is possible to treat larger systems than those previously studied. The 2-RDM matrix elements are calculated by imposing up to four-particle N-representability constraint conditions using standard semidefinite programing algorithms. The method is applied to the one- and two-dimensional XXZ spin 1/2 model of quantum magnetism. Several observables including the energy and the spin–spin correlation functions are obtained to assess the physical content of the variationally determined 2-RDM. Comparison with quantum-Monte Carlo and matrix product state simulations shows that in most cases only requiring up to three-particle positivity conditions is enough to correctly describe the ground-state properties of these one- and two-dimensional models.
Causes of color in purple- and yellow- quartz
Authors: Monarumit N , Sakkaravej S , Wanthanachaisaeng B , Saiyasombat C , Wongkokua W
Published: January 2021

Quartz is a variety of gemstone consisting of SiO2. The various colors of quartz are caused by Fe as a trace element. This study focused on the investigation of Fe oxidation states affecting colorations of purple- and yellow- quartz by X-ray absorption spectroscopy (XAS) and UV-Vis-NIR spectroscopy. The amethyst (purple- quartz) and citrine (yellow- quartz) were collected as the samples. As the XAS results, there was only Fe3+ oxidation state on both purple-and yellow- quartz considering with the absorption energy position at the Fe K-edge compared to the Fe-oxide chemical standards i.e., FeO and Fe2O3. However, the UV-Vis-NIR absorption spectra of the purple- and yellow- quartz were different. Therefore, we propose that the coloration of purple- and yellow- quartz was caused by Fe3+ oxidation states as the donor states at 3.59 eV and 2.28 eV with the different energy band gaps of the purple- and yellow- quartz that were 4.13 eV and 4.88 eV respectively derived from Tauc Plot method.
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

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

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

The 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

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

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

Within 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

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

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

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

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

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

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

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

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

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

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.
Heat transfer of a heat pipe using titanium dioxide as working fluid
Authors: Somasri S , Meena P
Published: January 2021

This research aims to study the heat transfer of a heat pipe using nanofluid as a working fluid by using a closed loop oscillating heat pipe with check valve (CLOHP/CV). The nanoparticles used this study are deionized water and TiO2 as a working fluid. The experiment the operating temperature was adjusted in the range of 60, 70 and 80 degrees Celsius and the inclination angle of the heat pipe in the range of 0 and 45 degrees. It was found that when using TiO2 as a working fluid, at inclination angle of 45 degrees, an operating temperature of 80 degrees Celsius, the highest heat transfer was 297.76 W, the highest heat flux was 2887.09 W/m2 the highest heat transfer coefficient was 1547. 53 W/m2 °C and the highest thermal efficiency was 0. 17. When using TiO2 as a working fluid, at inclination angle of 45 degrees, at operating temperature of 80 degrees Celsius the lowest heat resistance was 0. 26 C/W. In addition, we found that CLOHP/CV using TiO2, resulted in higher heat transfer ( 82. 23% ) than when using deionized water and lower heat resistance than using deionized water 92.85%.