bluuebunny/crossref_metadata_2025_split huggingface dataset:
Probing the galactic and extragalactic gravitational wave backgrounds with space-based interferometers
Authors: Mentasti G. , Contaldi C.R. , Peloso M. 
Published: June 2024

Abstract
We employ the formalism developed in [1] and [2] to
study the prospect of detecting an anisotropic Stochastic Gravitational Wave Background (SGWB)
with the Laser Interferometer Space Antenna (LISA) alone, and combined with the proposed
space-based interferometer Taiji. Previous analyses have been performed in the frequency domain
only. Here, we study the detectability of the individual coefficients of the expansion of the SGWB
in spherical harmonics, by taking into account the specific motion of the satellites. This
requires the use of time-dependent response functions, which we include in our analysis to obtain
an optimal estimate of the anisotropic signal. We focus on two applications. Firstly, the
reconstruction of the anisotropic galactic signal without assuming any prior knowledge of its
spatial distribution. We find that both LISA and LISA with Taiji cannot put tight constraints on
the harmonic coefficients for realistic models of the galactic SGWB. We then focus on the
discrimination between a galactic signal of known morphology but unknown overall amplitude and an
isotropic extragalactic SGWB component of astrophysical origin. In this case, we find that the two
surveys can confirm, at a confidence level ≳ 3σ, the existence of both the galactic
and extragalactic background if both have amplitudes as predicted in standard models. We also find
that, in the LISA-only case, the analysis in the frequency domain (under the assumption of a time
average of data taken homogeneously across the year) provides a nearly identical determination of
the two amplitudes as compared to the optimal analysis.
A solution method for decomposing vector fields in Hamilton energy
Authors: Zhao 赵 Xin 昕 , Yi 易 Ming 鸣 , Wei 魏 Zhou-Chao 周超 , Zhu 朱 Yuan 媛 , Lu 鹿 Lu-Lu 露露 
Published: June 2024

Abstract
Hamilton energy, which reflects the energy variation of systems, is one of the crucial instruments used to analyze the characteristics of dynamical systems. Here we propose a method to deduce Hamilton energy based on the existing systems. This derivation process consists of three steps: step 1, decomposing the vector field; step 2, solving the Hamilton energy function; and step 3, verifying uniqueness. In order to easily choose an appropriate decomposition method, we propose a classification criterion based on the form of system state variables, i.e., type-I vector fields that can be directly decomposed and type-II vector fields decomposed via exterior differentiation. Moreover, exterior differentiation is used to represent the curl of low-high dimension vector fields in the process of decomposition. Finally, we exemplify the Hamilton energy function of six classical systems and analyze the relationship between Hamilton energy and dynamic behavior. This solution provides a new approach for deducing the Hamilton energy function, especially in high-dimensional systems.
Enhancement of swimmer diffusion through regular kicks: analytic mapping of a scale-independent parameter space
Authors: Jurado Romero Arnau , Calero Carles , Rey Rossend 
Published: June 2024

Abstract
Depending on their mechanism of self-propulsion, active particles can exhibit time-dependent, often periodic, propulsion velocity. The precise propulsion velocity profile determines their mean square displacement and their effective diffusion coefficient at long times. Here, we demonstrate that any periodic propulsion profile results in a larger diffusion coefficient than the corresponding case with constant propulsion velocity. We investigate, in detail, periodic exponentially decaying velocity pulses, expected in propulsion mechanisms based on sudden absorption of finite amounts of energy. We show, both analytically and with numerical simulations, that in these cases the effective diffusion coefficient can be arbitrarily enhanced with respect to the case with constant velocity equal to the average speed. Our results may help interpret, in a new light observations on the diffusion enhancement of active particles.
Atmospheric extinction coefficients and night sky brightness at Bosscha Observatory
Authors: Yusuf M , Arwinata H I , Perhati T , Satya L , Jatmiko A T P , Ramadhan D G , Yap F , Ramadhan S 
Published: June 2024

Abstract
We conducted a continuous sky brightness monitoring project in 2023 using the 14-inch (f/7.2) Bosscha Robotic Telescope (BRT) with Bessel filters at Bosscha Observatory. We present the initial measurement result of the extinction coefficient and sky brightness of three photometric nights from July to September 2023 using absolute photometry methods on photometric standard stars. The measurement results indicate the values of the first-order extinction coefficients span from

k
b
′

= 0.1344 to 0.1596,

k
v
′

= 0.0931 to 0.1901,

k
r
′

= 0.1208 to 0.1592, and

k
i
′

= 0.0836 to 0.0967 with a typical error of 0.001 for two similar night. On September 12, our measurement results were

k
b
′

= 0.6186 ± 0.0081,

k
v
′

= 0.5404 ± 0.0104,

k
r
′

= 0.3684 ± 0.0122,

k
i
′

= 0.2483 ± 0.0191. Applying these values to the sky field reveals the average brightness in the V-band-pass, respectively 18.807 ± 0.061, 18.999 ± 0.052, and 18.867 ± 0.039, with a color index B − V of 0.421 ± 0.111, 0.236 ± 0.094 and 0.426 ± 0.064. The results are consistent with measurements from the transformed Sky Quality Meter (SQM) corresponding to the suitable filters.
Membership Study of Open Cluster NGC 6134 using HDBSCAN Clustering Algorithm
Authors: Yusuf M , Ramadhan D G , Jatmiko A T P , Perhati T , Ramadhan S , Arwinata H I , Yap F , Satya L , Mandey D , Arifyanto M I , Premadi P W 
Published: June 2024

Abstract
We present the results of our study on the membership of open star clusters in the southern hemisphere, NGC 6134. The position of NGC 6134 is located near the galaxy’s plane, so the apparent position in the sky is in an area with high stellar density. This poses a challenge in distinguishing between cluster member stars and field stars. For this purpose, we use the Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN) algorithm on astrometric data from Gaia Data Release 3 (DR3). We take stars as samples up to a distance of 90 parsecs from the cluster’s center as membership determination samples. The spatial scope of this sample is intentionally larger than previous studies on this star cluster, as some recent membership studies have concluded that the size of star clusters turns out to be larger than what has been reported. The results of our study produced a consistent number of members with the results of other studies with the same sample size. The clustering algorithm was then performed multiple times using different values of the radius sample. We determined that NGC 6134 has 888 members (membership probability ≥ 0.5), with a radius of 30 parsecs from the cluster’s center.
Using Space-weather HMI Active Region Patch (SHARP) parameters to identify solar-flare precursors for space weather forecasting
Authors: Herdiwijaya Dhani , Fernanda Chandra A 
Published: June 2024

Abstract
A solar flare results from the release of magnetic energy by magnetic-reconnection processes. It is preceded by the accumulation of energy, which is indicated by various magnetic parameters. An analysis of the magnetic parameters preceding the high energy release is therefore essential for understanding the occurrence of a solar flare. In this work, we studied 18 magnetic parameters from the Space-weather Helioseismic and Magnetic Imager (HMI) Active Region Patch (SHARP) database for X-class solar flares during the time span from May 10, 2010, to December 31, 2021, using a support vector machine. We found that the time-interval distribution between the maxima of the Space-weather HMI Active Region Patch (SHARP) parameters and solar flare events can be approximated by a Gaussian. About 67% of the maximum values of the SHARP indices occurred within a time window of 22.4 hours before a solar flare. This result strengthens the conclusion that the SHARP parameters can be employed to identify solar-flare precursors. In terms of Recall and True Skill Statistics, our support vector machine model performs better in forecasting solar flares than do previous results. By considering the significance of these 18 SHARP parameters, we found that seven parameters are the optimal number for further analysis.
Correlation Cosmic Ray Intensity Based on Variation in Solar Activity and Interplanetary Plasma Parameters Using Principal Component Analysis (PCA)
Authors: Putri A N I , Herdiwijaya D , Hidayat T 
Published: June 2024

Abstract
For a long time, scientists have been investigating the relationship between the strength of cosmic rays and the number of sunspots. Several studies have discovered an anti-correlation between cosmic ray power and the number of sunspots, with some differences in time lag between solar cycles. So far, the distinctions that have surfaced are a mystery. This effort will estimate solar activity and interplanetary space parameters such as the sunspot number, solar wind speed, Interplanetary Magnetic Field (IMF), Heliospheric Current Sheet (HCS) tilt, and halo CME speed. The data ranges from 1749 to 2022, with time resolutions ranging from daily to monthly. To study the association between cosmic ray intensity and these five qualities, the Principal Component Analysis (PCA) approach was utilized. According to the data, all measurements demonstrate an anti-correlation with the intensity of cosmic rays. They also contribute to the modification of cosmic rays.
RFI measurements at Bosscha observatory to prepare a new VGOS station
Authors: Ramadhan S. , Hidayat T. , Suryana J. , Romadhoni A. , Kurniasari M. 
Published: June 2024

Abstract
A new VGOS (VLBI Global Observing System) radio telescope will be constructed at Bosscha Observatory Lembang, West Java, in cooperation between Shanghai Astronomical Observatory (SHAO) and Institut Teknologi Bandung. One of the preparation steps is to conduct RFI (Radio Frequency Interference) measurements to obtain the RFI environment from the vicinity of the observatory. In this work, we report preliminary measurements of the RFIs that were done for several days in August and September 2023. Instruments used includes: A-INFOTM LB-20180 horn antenna, Wright TechnologiesTM low noise amplifier, and AaroniaTM Spectran V5 80200 OEM spectrum analyzer. The frequency range of 2.0 - 18.0 GHz is targeted referring to VGOS frequencies. Measurements in one day are carried out for about 24 hours in eight cardinal directions and two polarizations. The results and analysis are presented in spectral power flux density plots.
Study of Asia-Pacific Plate Tectonic Motion by Using VLBI Observation
Authors: Nurul Huda I. , Putri N. S. E. , Hidayat T. , Shu F. , Li J. 
Published: June 2024

Abstract
In the near future, a new radio telescope will be installed in Bosscha Observatory, Indonesia. This telescope will be integrated into the geodetic Very Long Baseline Interferometry (VLBI) network notably into the VLBI Global Observing System (VGOS). In this study, we aim to highlight the use of a geodetic VLBI network to study the plate tectonic movement. We use the VLBI session called Asia-Pacific space geodynamics (APSG) program to measure the crustal movement in the Asia-Pacific region, particularly its velocity. We compared the VLBI analysis results with plate tectonic model NUVEL1-A. Generally, it shows that the tectonic plate velocity from VLBI analysis has a good agreement with the model.
Thai National Radio Astronomy Observatory Project and a future South-East Asian VLBI Network
Authors: Sugiyama Koichiro , Jaroenjittichai Phrudth , Leckngam Apichat , Kramer Busaba H. , Rujopakarn Wiphu , Soonthornthum Boonrucksar , Sakai Nobuyuki , Hidayat Taufiq , Zainal Abidin Zamri , Carlos Algaba Juan , Ngoc Diep Pham , Poshyachinda Saran ,   TNRO project team members
Published: June 2024

Abstract
NARIT initiated a national flagship project in 2017 for development of radio astronomy and geodesy in Thailand. In this project, a 40-m Thai National Radio Telescope (TNRT) and a 13-m VLBI Global Observing System radio telescope are constructed in Chiang Mai. The 40-m TNRT is the largest telescope for radio astronomy in South-East Asia. Its flexible operation with a wide-frequency coverage 0.3-115 GHz will allow us to uniquely contribute to the time-domain astronomy as well as carry out unbiased surveys for a wide variety of research fields, which were published in a white paper. Within the framework of collaboration with VLBI arrays in the world, TNRT will drastically improve the imaging quality and performances based on its unique geographical location. Through commissioning of the L-band system, the 1st Call for Proposals of the 40-m TNRT in the L-band1 has been internationally announced on 10th October 2023, TST 10 am. Future vision for establishment of forthcoming regional VLBI networks based on TNRT is also introduced: Thai National VLBI Array and South-East Asian VLBI Network in collaboration with Indonesia, Malaysia, and Vietnam.
The Development of Android-Based Interactive Learning Media on the Topic of Discussing the Atmosphere
Authors: Raisal A Y , Rakhmadi A J , Hidayat M 
Published: June 2024

Abstract
Low comprehension and lack of interest among students are caused by the lack of variety in learning media. Consequently, the creation of more diverse learning materials is required. The aim of this study is to create interactive learning resources for Android users that cover the topic of atmosphere discussion. Using the ADDIE development process (analyze, design, development, implementation, and evaluation), this kind of study is Research and Development. Expert validation in media and materials yielded very valid and valid criteria, respectively. The expert validation results demonstrate that the created learning media are suitable for use in the educational process. Since PowerPoint is the most often used presentation tool by educators, the media was created with it in mind, making it easier for teachers to create Android-based learning materials. In the meantime, development and implementation trials must be conducted to assess the degree of applicability and efficacy of the media.
Performance analysis of reed valve of rolling piston compressor based on fluid-structure interaction
Authors: Chen Debiao , Zhang Chaolei , Gao Wenzhao 
Published: June 2024

Abstract
To analyze the influence of different thickness reed valves on the exhaust pressure pulsation, a two-way fluid-structure interaction model of the reed valve of the rolling piston compressor is established in this paper. Based on the results of the two-way fluid-structure coupling analysis, the deformation displacement and the influence on the pressure pulsation of the rolling piston compressor in a cycle under different reed valve thicknesses are compared. The analysis results show that under specific working conditions, with the increase of the thickness of the reed valve, the maximum deformation displacement decreases, the peak value of the exhaust pressure pulsation decreases, and there will be a phenomenon of early closing. The overall analysis obtains a better valve thickness. The research results have certain guiding significance for optimizing the structure of the reed valve and the comprehensive performance optimization of the rolling piston compressor.
Thermal characteristics analysis of hydrostatic lubrication of involute spline guideway
Authors: Xi Haoran , Li Dong , Qi Houjun , Jiao Yuze , Zheng Shuguo 
Published: June 2024

Abstract
Aiming at the locking phenomenon of YK5115AK2 gear shaper under high-speed operation, based on fluid-solid coupling, the maximum temperature rise and deformation of guide rails with different convection modes are analyzed. The control variable method is used to analyze the oil film gap, feed rate, oil supply pressure, hydraulic oil viscosity, and sealing edge design parameters of the guide rail, and the relationship between these parameters and the maximum temperature rise of the guide rail is discussed. The results show that when the working conditions are satisfied, the larger the oil film clearance is, the smaller the feed speed is, and the smaller the oil supply pressure should be adopted. Therefore, the appropriate low-viscosity hydraulic oil should be selected. Under the condition of meeting the requirements of working conditions, the short sealing oil edge should be shortened as much as possible, while the long sealing oil edge can be extended appropriately to achieve the best thermal steady-state performance of the guide rail.
Effect of tempering temperatures on microstructure and mechanical properties of high-strength steel
Authors: Zhang Xiaolu , Li Rui , Sun Zhiyan , Zhang Yunfei , Zhao Yingli , Fan Mingqiang , Ji Shuang , Chen Wei , Zhao Nan , Zhang Xinyue 
Published: June 2024

Abstract
This study thoroughly examines the effects of tempering temperature on the structure and mechanical properties of high-strength steel. The objective is to establish a solid foundation of raw materials for the production of relevant equipment. Experimental results show that: when tempering temperatures between 180°C~300°C, with the increase of tempering temperature, the tensile stress of the material decreases gradually, and the yield strength tends to increase. The comprehensive mechanical properties of the alloy are optimized in plasticity and toughness, and it can be seen that the strength reaches an excellent balance at 180°C. The carbide precipitation and impact fracture characteristics are analyzed by scanning electron microscopy and transmission electron microscopy, and it is found that a large number of needle-shaped ε-carbides are precipitated in the martensite lath, and the size of the ε-carbides increases with the increase in tempering temperature, which is the reason for the gradual decrease in the yield strength of the experimental steel with the increase in tempering temperature.
Study on buckling of thin-walled composite cylinder under C-SS boundary condition
Authors: Yang Zilong , Li Wusheng , Yang Fujiang 
Published: June 2024

Abstract
The spigot is a common connecting method for composite containers with thin walls. The fixture is closer to the thin-walled cylindrical shell with one end clamped and one end supported (C-SS) than the boundary conditions of typical pressure vessels, which are supported (SS-SS) or clamped (C-C) at both ends. Under the boundary condition, there are very few calculations and experimental research. A buckling model of the thin-walled composite vessel was built, and the critical load was determined using the energy technique and the classical thin-walled theory. Using nonlinear numerical analysis and FEM, the buckling mode was simulated. Numerical examples were used to examine the impacts of the spigot’s length, boundary conditions, layup thickness, and sequencing on the critical load. The findings indicate that a shorter spigot, a thicker layup, and a small-angle layer closer to the center all increase the critical load. The boundary conditions of SS-SS, C-S, and C-C experienced increasing critical loads in that order; the latter was around 1.5~2 times more than the former. Ultimately, external pressure tests were used to evaluate the buckling critical loads of two distinct laminated thin-walled composite vessels, confirming the correctness of both the FEM results and the theoretical model. The variance for the former was 15%, while the latter was 8%. The findings can serve as guidelines for designing interference and winding pre-stress spigots and the structural stability study of thin-walled composite vessels.
The influence of plasma arc composite laser welding parameters on aluminum alloy weld seam weld penetration
Authors: Wu Xiaocui , Liu Changjun , Liu Jian 
Published: June 2024

Abstract
In laser and plasma arc compound heat source welding technology, we collected a series of comparative data for a full range of analyses. We proceeded with an in-depth discussion of these two welding technologies in terms of the weld penetration, the melted width, the shape and size of the weld, laser power, heat source spacing, and welding speed. After research, we found that during laser-arc hybrid welding, weld penetration is very sensitive to laser power and welding speed but relatively less sensitive to heat source spacing and welding speed.
Preparation and properties of high-density polyethylene / thermoplastic polyurethane / calcium sulphate whisker composites
Authors: Zhang Daohai , Xu Yuhuan , Liu Guilan , Xue Yu , Shi Lianjun , Chen Qianlin , Xie Tian 
Published: June 2024

Abstract
In this study, composites of High-density polyethylene (HDPE) / Thermoplastic polyurethane (TPU)/Calcium Sulfate Whiskers (CSW) with varying mass fractions were created by using a melt blending process. The aim was to analyze how the addition of CSW to the composites impacted their mechanical and thermal properties as well as the interplay between the substrates. The findings demonstrate that the inclusion of CSW whiskers in HDPE/TPU composites led to a significant enhancement in their mechanical and thermal properties. Furthermore, a robust interfacial adhesion was observed between CSW whiskers and the HDPE/TPU matrix polymer.
Performance improvement and optimization of nano-based coatings
Authors: Peng Chenglong , Liu Xiaoqin 
Published: June 2024

Abstract
Polyaniline Graphene (PAGO) is a composite nanomaterial, which is mainly prepared from aniline and Graphite oxide (GO) by in-situ polymerization. Through the action of PAGO, the corrosion resistance of water-based anti-corrosion coatings can be effectively improved. The microstructure of PAGO was analyzed by XRD, SEM, and TEM, and the influence of the number of composite nanomaterials and the mass ratio of Polyaniline to Graphene on the performance of the paint film was analyzed. The results show that the corrosion resistance of waterborne epoxy resin can be effectively improved by combining the passivation effect of Polyaniline on a metal substrate with the barrier effect of lamellar Graphene.
Anti-icing properties of superhydrophobic surface with nanoscale pores
Authors: Li Bo , Xiang Huiying , Yuan Yuan 
Published: June 2024

Abstract
Outdoor equipment icing has a great impact on people’s production and life. The study of superhydrophobic (SHP) coating or surface is expected to obtain an excellent anti-icing effect. However, SHP coatings or surfaces still face the failure of superhydrophobic properties and poor durability. Herein, the anti-icing properties of SHP were improved by constructing a nano-scale deep pore structure on the aluminum substrate surface. Compared with the untreated surface, the SHP surface shows a longer frosting time (42 min) and extremely small ice adhesive strength (3 kPa). This study provides a durable SHP surface for icing prevention of outdoor equipment.
Research on full position CMT welding process for circular pipes
Authors: Lei Jiaxuan , zhang Fenglong , Ren Xianghui , Han Shanguo , Li Zhenlong 
Published: June 2024

Abstract
The CMT welding technology is adopted to solve the difficulties in full-position welding of circular pipes, and a robotic arm is controlled to achieve automatic full-position welding. The characteristics and laws of weld formation are studied by adjusting technology parameters like welding current, angle, and speed. The results show that once the welding current increases, the fusion depth and width of the weld simultaneously increase. However, as the welding speed increases, the depth and width of fusion decrease. Root welding experiments indicate that the optimal morphology of the root weld is achieved under the welding current of 200 A at the 0.2 m/min welding speed. In the weld filling experiment, both the left and right passes use the welding current of 260 A at the 0.2 m/min welding speed, which can fill the weld with two passes and achieve complete well formation.