bluuebunny/crossref_metadata_2025_split huggingface dataset:
Site-testing at the Muztagh-ata Site V. Nighttime Cloud Amount during the Last Five Years
Authors: Xu Jing , Feng Guo-jie , Pu Guang-xin , Wang Le-tian , Cao Zi-Huang , Ren Li-Qing , Zhang Xuan , Ma Shu-guo , Bai Chun-hai , Esamdin Ali , Li Jian , Tian Yuan , Wang Zheng , Zhao Yong-heng , Shi Jian-rong 
Published: March 2023

Abstract
The clarity of nights is the major factor that should be carefully considered for optical/infrared astronomical observatories in site-testing campaigns. Cloud coverage is directly related to the amount of time available for scientific observations at observatories. In this article, we report on the results of detailed night-time cloud statistics and continuous observing time derived from ground-based all-sky cameras (ASCs) at the Muztagh-ata site from 2017 to 2021. Results obtained from acquisition data show that the proportion of the annual observing time at the Muztagh-ata site is 65%, and the best period with the least cloud coverage and longer continuous observing time is from September to February. We made a comparison of the monthly mean observing nights obtained from our ASC and CLARA data set, and results show that the discrepancy between them may depend on the cloud top heights. On average, this site can provide 175 clear nights and 169 nights with at least 4 hr of continuous observing time per year.
Collaborative Simulation of Mechanical Structure and Control Systems of Leighton Chajnantor Telescope
Authors: Yao Yi-Wei , Chen Wei-Rui , Wang Zheng 
Published: March 2023

Abstract
Leighton Chajnantor Telescope (LCT) will be moved from the summit of Maunakea, Hawaii to Chajnantor Plateau, Chile and be refurbished there. Strong wind disturbance at the new site will bring great challenges to the servo control of LCT. It is necessary and important to develop a simulation platform that behaves as close as possible to the real telescope for testing the performance of the designed servo controller. In this paper, a collaborative simulation platform of LCT based on Adams and Matlab/Simulink is constructed. On this platform, the mechanical structure model of LCT can be integrated with its control system model such that a collaborative simulation of the mechanical structure and the control system of LCT can be conducted. The mechanical structure model of LCT, which contains both rigid body models (i.e., the mount) and flexible body models (i.e., the primary reflector), is developed by using Adams. The servo system model and the wind disturbance model are constructed by using Matlab/Simulink. By conducting collaborative simulation, the performances of the servo controller based on the rigid body model and the rigid-flexible coupling model of LCT are compared. The comparison shows that the controller designed based on the rigid body model does not perform well when it is employed to control the rigid-flexible coupling model of LCT. However, by readjusting parameters of the servo controller, its performance can be further improved when applied to the rigid-flexible coupling model. Therefore, an LCT model of integrated mechanical structure and control systems is very helpful for analyzing its performance more accurately and designing a better servo controller.
Full-frame Data Reduction Method: A Data Mining Tool to Detect the Potential Variations in Optical Photometry
Authors: Dai Zhi-Bin , Zhou Hao , Cao Jin 
Published: March 2023

Abstract
A Synchronous Photometry Data Extraction (SPDE) program, performing indiscriminate monitoring of all stars appearing in the same field of view of an astronomical image, is developed by integrating several Astropy affiliated packages to make full use of time series observed by traditional small/medium aperture ground-based telescopes. The complete full-frame stellar photometry data reductions implemented for the two time series of cataclysmic variables: RX J2102.0+3359 and Paloma J0524+4244 produce 363 and 641 optimal light curves, respectively. A cross-identification with SIMBAD finds 23 known stars, of which 16 are red giant-/horizontal-branch stars, 2 W UMa-type eclipsing variables, 2 program stars, an X-ray source and 2 Asteroid Terrestrial-impact Last Alert System variables. Based on the data products from the SPDE program, a follow-up light curve analysis program identifies 32 potential variable light curves, of which 18 are from the time series of RX J2102.0+3359, and 14 are from that of Paloma J0524+4244. They are preliminarily separated into periodic, transient, and peculiar types. By querying for the 58 VizieR online data catalogs, their physical parameters and multi-band brightness spanning X-ray to radio are compiled for future analysis.
Period Investigation on Two W UMa Binaries HH UMa and V1175 Her
Authors: Chang Linfeng , Zhu Liying , Meng Fangbin 
Published: March 2023

Abstract
HH UMa and V1175 Her are two W UMa contact binary systems whose periods were reported as undergoing secular increase. In this paper, we improved their period analyses with a more extensive database of eclipse timings, finding that both periods show cyclic variation. The cyclic variation could be attributed to a Light Travel Time Effect induced by a third body. Both circular orbit and eccentric orbit cases were considered. For HH UMa, the cyclic variation with a period of around 20 yr has been detected, which may be caused by a third body with the mass larger than 0.23 M
⊙. However, no parabolic variation was detected in its O−C curve, implying the balance of the mass transfer between the two components and the angular momentum loss from the binary system. As to V1175 Her, a long-term period increase superposed on a periodic oscillation was detected. The period increase with a rate of about dP/dt = 2 × 10−7day yr−1 indicates the mass transfer from the less massive component to its companion. The cyclic variation of about 7.5 yr could be caused by a hierarchical third body with a minimal mass exceeding 0.46M
⊙ orbiting around the central binary. This mass is larger than that of the less massive component of the binary, which means that the secondary component was not replaced by the third body during early stellar interactions, implying that it keeps original dynamical information. By removing angular momentum from the central binary system, the tertiary component has played a significant role in the formation of contact binaries.
Deciphering the relationship between vegetation and Indian summer monsoon rainfall
Authors: Samuel Jerry B , Chakraborty Arindam , Paleri Anagha 
Published: March 2023

Abstract
Land surface utilization in the Indian subcontinent has undergone dramatic transformations over the years, altering the region’s surface energy flux partitioning. The resulting changes in moisture availability and atmospheric stability can be critical in determining the season’s monsoon rainfall. This study uses fully coupled global climate model simulations with idealized land cover to elucidate the consequences of land surface alterations. We find that an increase in forest cover, in general, increases precipitation in India. However, precipitation is not a linear function of forest-covered-area due to the spatially heterogeneous nature of the impact. A fully forest-covered India receives less precipitation than when the forest covers only the eastern side of India, occupying just about half the area. This signifies the importance of the east-west gradient in vegetation cover observed over India. Using an energy balance model, we diagnose that the diverse nature of this precipitation response results from three different pathways: evaporation from the surface, the net energy input into the atmosphere, and moist stability. Evaporation exhibits a linear relationship with forest-covered-area and reveals minimal spatial heterogeneity. On the contrary, the influence through the other two pathways is found to be region specific. Rainfall modulation via changes in net energy input is dominant in the head Bay of Bengal region, which is susceptible to convective systems. Whereas impact through stability changes is particularly significant south of 20∘ N. In addition, we find that moisture advection modulates the significance of these pathways over northwest India. Thus, the impact of land cover changes act via three effective mechanisms and are region dependent. The findings in this study have broader ramifications since the dominant region-specific mechanisms identified are expected to be valid for other forcings and are not just limited to the scenarios considered here.
A 3D characterization of equiaxed grains induced by mediated nucleation in additively manufactured Inconel 718
Authors: Cazic I , Engstler M , Zollinger J , Ghanbaja J , Kandaoui M El , Appolaire B 
Published: March 2023

Abstract
In additive manufacturing of Ni-based alloy IN718, what causes Icosahedral Short-Range Order (ISRO) or iQC mediated nucleation of equiaxed grains is still not understood. In order to have a better comprehension of the microstructure formation, a more comprehensive characterization both on grain structure and chemical heterogeneities must be achieved. In this work, a scanning electron microscope equipped with a focused ion beam (FIB) allowed to perform a 3D EDS chemical analysis and EBSD orientation mapping of the volume in an equiaxed grain zone. After the 3D reconstruction of the equiaxed grains has been performed, grain-to-grain orientation analysis allowed to analyze multiple twin boundaries orientation relationships in a volume containing hundreds of grains. Chemical mapping using EDS allowed to identify TiC inclusions from which a five-fold symmetry axis seem to emerge, indicating a potential nucleation site. Such areas were analyzed in transmission electron microscopy (TEM) to investigate the different present phases. The nucleation sequence and potential origin of mediated nucleation are further discussed, opening new prospects for grain refinement in additively manufactured nickel-based alloys.
β grain refinement during solidification of Ti-6Al-4V in Wire-Arc Additive Manufacturing (WAAM)
Authors: Kennedy J. R. , Davis A.E , Caballero A.E. , Pickering E.J. , Prangnell P.B. 
Published: March 2023

Abstract
Constructing titanium aerospace parts by near-net-shape processing has the potential to greatly reduce cost and lead time, one method for this is Wire-Arc Additive Manufacturing (WAAM). Conventional WAAM processing with the most common Ti alloy, Ti-6Al-4V, results in solidification by epitaxial growth from previously deposited layers and a structure dominated by columnar β grains which are heavily <001> fibre textured and cm’s in scale. In order to prevent these large grains from forming, while maintaining deposition parameters, the solidification conditions were modified by the additions of particles to the melt; either using inoculant, TiN particles, or the solutal growth restrictor, Y, also added as elemental powder that dissolved in the melt. The powder particles were added by adhering them to the deposited tracks to avoid the costs of manufacturing new wires. With TiN inoculants the morphology of β grains was completely modified to equiaxed grains averaging 300 μm in diameter. Y additions narrowed the columnar grains from 1-2mm to 100-300 μm. Y also induced a change to equiaxed grains, late in solidification, in the region which was remelted by subsequent deposition. However, Yttria particles were found to have formed interdendritically with an interconnected skeletal morphology. High-resolution EBSD analysis showed both TiN and yttria particles exhibit specific orientation relationships with the solidified β grains, which were confirmed experimentally.
Large-scale phase-field simulations for dendrite growth: A review on current status and future perspective
Authors: Takaki T 
Published: March 2023

Abstract
The current status of large-scale phase-field (PF) simulations for dendrite growth is reviewed by focusing on the study conducted by our group. The discussion includes the competitive growth of multiple columnar dendrites, dendrite growth with liquid flow and solid motion, permeability prediction, and cross-scale simulations using the PF method. All PF simulations introduced here were executed using a graphics processing unit (GPU) or a GPU supercomputer to significantly accelerate the PF simulations. Finally, the future perspectives of large-scale dendrite-growth PF simulations are discussed.
Effect of laser scanning velocity on the microstructural changes and mechanical properties of the H13 steel part treated by laser surface remelting
Authors: Xie Jichang , Di Ruifeng , Li Jishuai , Liu Yanan , Raoelison Rija Nirina , Rachik Mohamed 
Published: March 2023

Abstract
This paper investigates the effect of laser scanning velocity on the structural changes and mechanical properties of a H13 steel part treated by laser surface remelting. A high energy density laser with a large laser beam was used to improve the processing efficiency. The room temperature phases are dominated by martensite, retained austenite, and carbides. The laser treatment effects under various exposition conditions are compared in terms of heat affected depth, surface topography, and mechanical properties. The strengthening mechanisms include grain refinement, dislocation and precipitation strengthening, which act simultaneously during the laser remelting process to confer a high hardness at the surface of the H13 steel workpiece. Due to its higher yield strength and lower elongation, failure in the remelting zone occurred at the grain boundaries of the dendrites and in between the heat affected zone (HAZ) and the parent metal (Base Metal). These results can support the mass production of surface hardened H13 steel moulds using a laser treatment (high laser density and large laser heat source) with apprehensible changes of properties.
Grain structure predictions for metallic additive manufacturing processes
Authors: Dreelan D , Ivankovic A , Browne D J 
Published: March 2023

Abstract
Additive manufacturing has transformed the way we think about component fabrication. Generating a geometry in a layer-by-layer fashion presents many advantages over traditional subtractive methods, but also presents many challenges pertaining to the highly localised and energetic nature of the heat source. Since the material passes through multiple heating and cooling cycles throughout the build, some of which completely melt and erase the microstructure, a dynamic simulation is necessary to determine the grain structure that emerges. Grains are generally, but not exclusively, highly textured with columnar grains commonly spanning multiple layers. Fast, efficient and parallelised envelope cellular automata based models are used to simulate the nucleation and growth of the individual crystals that comprise the grain structure, with trade-offs being made between intra-grain detail and computational efficiency so that meso-scale simulations are possible. Simplified, but physically sound thermal models are used to predict the thermal conditions at the melt pool periphery, which are weakly coupled to the grain growth model. Dendrite tip kinetics models are used to determine alloy specific growth laws as a function of local undercooling. The effect of various processing parameters on as-solidified grain size, morphology and texture are investigated for aluminium alloys 3D printed by laser powder bed fusion.
On modelling conjugated heat transfer in the thin slab CC mold and solid shell formation under the applied EMBr
Authors: Vakhrushev A , Karimi-Sibaki E , Wu M , Ludwig A , Nitzl G , Tang Y , Hackl G , Watzinger J , Bohacek J , Kharicha A 
Published: March 2023

Abstract
Continuous casting (CC) became one of the dominant steel production technologies throughout last decades. Better quality, energy savings and high production rates are the main aims of the research especially in the field of the thin slab casting (TSC). The electromagnetic brake (EMBr) is applied to control the highly turbulent flow after the fresh melt is fed through the ports of a submerged entry nozzle (SEN). The numerical modelling is a perfect tool to investigate the multiphase phenomena of the turbulent flow in the CC mold, heat transfer and solidification coupled with the effects of the magnetohydrodynamics (MHD). Traditionally the heat transfer in the CC mold during the numerical simulations is predefined by the heat flux profile which could be taken from the plant measurements, published data, or is described by the semi-empirical formulas. In all these cases the heat extraction in the CC mold cavity is strictly predefined and is not significantly influenced by the transient flow behavior. Moreover, the heat flux, used in a simulation, is frequently measured for the different flow pattern inside the mold. That is especially important when the EMBr effects on the solid shell formation are investigated. Thereby, the presented study considers the coupled heat transfer in the water-cooled copper mold, including the averaged thermal resistance between the slab and mold, implemented using OpenFOAM® open-source CFD software. The melt flow, the temperature field, and the induced electric current density are compared between the traditional approach (the applied heat flux) and the modelled heat transfer in the TSC mold. Different scenarios are studied without and with the applied magnetic field.
Potential eutectic accumulation in single crystal turbine blade due to geometry effect: a numerical study
Authors: Zhang H J , Liu X S , Ma D X , Ludwig A , Kharicha A , Wu M H 
Published: March 2023

Abstract
Inhomogeneous distribution of the eutectic phase in single crystal (SC) turbine blades is detrimental to its mechanical properties. In a recent publication, it was reported that an accumulation of eutectics was observed on the upper surface of solidification units (e.g. shroud of a turbine blade), whereas fewer eutectics were detected at the bottom. This kind of casting defect brings a huge challenge to the production of turbine blades since the accumulated eutectics cannot be dissolved completely by heat treatment. A sample with three pairs of platforms/shrouds was designed to study the geometry effect on eutectic accumulation. In the current study, the simulation was performed by coupling ProCAST with our previously developed multiphase volume-average solidification model. In the first step, the thermal field including radiation in the furnace and heat conductivity in the casing and mould was calculated via ProCAST. Then, the obtained temperature profiles were set as thermal boundary conditions of the casting to predict the eutectic accumulation and formation of freckles. Based on the simulation results, convective plumes arising from the thermosolutal buoyancy transport solute-enriched liquid upward, which causes the solute pile-up and the final eutectic accumulation at the top surface in each platform. Freckles accompanied with eutectic accumulation was also observed at the corner of the sample. The calculated inhomogeneous distribution of the eutectics agrees well with experimental observations. Knowledge about the geometrical effect on eutectic accumulation is extended.
Anisotropic Mechanical Behaviour of Nickel Based Single Crystal Superalloy CMSX-4 for Prediction of Grain Recrystallization during Homogenization Heat Treatment Following Solidification
Authors: Hazemann E , Zhang Y , Inal K , Gandin Ch A , Long M , Niane N T , Pinto Mora A , Maguin V , Leduc M , Jaquet V , Bellet M 
Published: March 2023

Abstract
In the present work, a methodology to identify parameters of an elastic viscoplastic behaviour law is presented. Orthotropic elasticity and Hill48 plastic anisotropy for as-cast CMSX-4 are considered. In order to obtain the corresponding parameters by inverse analysis, an experimental database is built by tensile/relaxation tests at constant temperatures between 800°C and 1200°C on specimens oriented along <001>, <110> and <111> directions at different strain rates. Tests are performed with a resistive heating machine, using infrared thermography and digital image correlation. The obtained mechanical behaviour is very dependent on specimen orientation at all tested temperatures. Recrystallization behaviour is also very relevant to the specimens’ orientation.
Observation of peritectic couple growth for a hyper-peritectic alloy under microgravity conditions
Authors: Ludwig A , Mogeritsch J P 
Published: March 2023

Abstract
Under specific conditions, peritectic alloys can form microstructures that behave similar to regular eutectic alloys, with two solid phases growing in a coupled manner directly from the melt. This so-called peritectic couple growth (PCG) is significantly affected by convection. Thus, Bridgman-type experiments were performed onboard the International Space Station using the transparent peritectic alloy, tris(hydroxymethyl)aminomethane–neopentyl glycol (TRIS–NPG). Under these purely diffusive conditions, the formation of PCG, its development over time, and its dependence on the applied process conditions were studied. In this paper, we provide novel insights into the appearance of PCG and the challenges associated with corresponding experiments.
In situ solidification of eutectic Al-33wt%Cu droplets
Authors: Valloton J , Mahdi N , Rabago L , Chung J , Henein H 
Published: March 2023

Abstract
Al-33wt%Cu eutectic droplets were rapidly solidified using Impulse Atomization, a drop tube technique. The samples were then processed in situ in an SEM using an HTN-0101 MEMS heating chip manufactured by Norcada. The temperature of the chip, as well as the heating and cooling rates, can be easily set using the chip’s control software, allowing for heating and cooling rates as fast as 1000°C/second. The droplets were heated above the eutectic melting temperature. Thanks to the oxide skin, the droplets retained their spherical shape, which allowed in situ solidification experiments. The live feed of the surface of the droplet obtained with the SEM was recorded during the experiments alongside the temperature-time profile. Various cooling rates were imposed and the liquid samples were shown to undercool prior to solidification. The resulting eutectic morphologies and spacings were then analyzed as a function of the cooling rates and undercoolings.
Microstructure evolution during directional solidification of off-eutectic Al-Cu-Mg alloys
Authors: Ezemenaka Dominic , Small Samuel , Genau Amber 
Published: March 2023

Abstract
Building on previous studies of invariant ternary eutectic Al-Al2Cu-Al2CuMg, this work aims to deepen our understanding of the microstructural possibilities in the Al-rich region of the Al-Cu-Mg phase diagram by considering the solidification behaviour of several off-eutectic compositions. Four Al-Cu-Mg alloys were directionally solidified at a constant growth rate (1.25 μm/s) and thermal gradient (9-14 K/mm) using a Bridgman-type furnace and analysed using a combination of scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and differential scanning calorimetry. Qualitative and quantitative analyses showed a preference for faceted Al2Cu dendrites surrounded by a ternary eutectic matrix in the two Mg-poor samples, even though one composition was not in the primary Al2Cu phase region. The two Al-poor samples consisted of large regions of three different intermetallic phases and little eutectic, making these samples very brittle.
Preliminary system for data assimilation to infer material parameters from directional solidification experiments: twin experimental study using phase-field method
Authors: Imai Y , Sakane S , Ohno M , Yasuda H , Takaki T 
Published: March 2023

Abstract
The integration of phase-field (PF) simulations and in situ observations is a promising approach for understanding dendrite growth. In this study, a preliminary data assimilation system is developed to integrate PF simulations and in situ real-time X-ray radiography during the directional solidification of a binary alloy. In this system, only the region around the tip of a primary arm is used for data assimilation. The validity of the developed system is confirmed through twin experiments for columnar dendrite growth with different inclined angles of preferred growth direction.