bluuebunny/crossref_metadata_2025 huggingface dataset:
Designing Lean Maintenance Using Total Productive Maintenance Method – A Case Study at Wiring Harness Production
Authors: Hafidh Al Farihi Ahmad , Sumartini Susy , Herdiman Lobes
Published: December 2023

Consumer demand for 4-wheeled and 2-wheeled motorized vehicles in Indonesia is increasing yearly. In 2022, car sales increased by 18.1%. At the same time, motorcycle sales increased by 3.24%. Automotive companies will compete with each other to meet the needs of consumers in the future. This is also true for automotive parts suppliers. PT XYZ is a company that supplies wiring harnesses for the needs of motorized vehicle components. Currently, the company is facing a problem with overtime of up to 4 hours in several production lines. The company missed the production target because the production plan had not considered any waste that happened on the production floor. Downtime of machines can stop production on the line. Downtime can occur due to machine failure. The company must choose the proper steps for resolution. If waste continues to be ignored, the company will struggle to compete with its competitors. This research aims to solve the waste problem through the Total Productive Maintenance (TPM) Method. Several steps are used to solve the problem: root cause analysis, determining the TPM pillars applied, RCM, and realization of TPM pillars. The research results are lean maintenance design from completing TPM pillars, such as autonomous maintenance, planned maintenance, and development management.
Improvement of The Food Safety Management System for Tea-Producing SMEs Based on HACCP
Authors: Kristiningrum Ellia , Tri Setyoko Ajun , Pribadi Adinugroho Teguh , Agus Susanto Danar , Isharyadi Febrian , Ayundyahrini Meilinda
Published: December 2023

Tea is a beverage product that has many health benefits. The growth of the small and medium scale industry (SMEs) is able to push this industry sector to become the second largest beverage industry after mineral water in Indonesia. Controlling the risk of food safety hazards is very important for this sector to produce products that are safe for consumption. Focusing on prevention, Hazard Analysis and Critical Control Points (HACCP) can assist change including designing treatment equipment and procedures. This work provides an overview of the development of a HACCP system in a teaproducing SME-scale industry. The methodology used is based on the guidelines for developing a HACCP system. The results of the work found four critical control points (CCP) in the tea production line and as a recommendation, it is necessary to take corrective actions in receiving raw materials, chopping, grinding and drying tea.
The Effect of Adding Nanoparticles from the Synthesis of Arc Discharge on the Performance of Lithium Ion Batteries
Authors: Hanif Khilalul , Anwar Miftahul , Adriyanto Feri , Nizam Muhammad , Slamet Saputro Joko
Published: December 2023

Lithium-ion battery is a type of rechargeable battery. A lithium-ion battery consists of several components, such as electrodes (anode and cathode), separators, and electrolytes. One factor that can affect a battery's performance is the quality of the electrodes. The commonly used anode consists of graphite powder. Currently, there is nanotechnology, namely the application of technology to make materials on the nanoscale (1-100 nm). The advantage of nanoparticle technology is its openness to be combined with other technologies, opening up opportunities to produce more perfect delivery systems. In this research, the production of lithium-ion batteries was carried out by adding nanoparticles as an anode. The nanoparticles used result from arc discharge synthesis with varying currents of 40A and 70A. The test results show that current variations in the arc-discharge synthesis process in the manufacture of lithium-ion battery anode nanoparticles affect the performance of lithium-ion batteries. Batteries using 70A nanoparticle anodes have a higher specific capacity than batteries using 40A nanoparticle anodes during chargedischarge. However, the specific capacity of the battery with nanoparticle anode is lower than that of the battery with graphite anode. When charging, the time needed for a battery that uses a 70A nanoparticle anode is shorter than a battery that uses a graphite anode and 40A nanoparticles. When discharging a battery that uses a 40A nanoparticle anode has a shorter time compared to a battery that uses a 70A nanoparticle and graphite anode.
Sustainability and Risk in Manufacturing: A Bibliometric Analysis and Future Research Direction Using R
Authors: Syahrullah Yudi , Ciptomulyono Udisubakti , Sari Ratna
Published: December 2023

The manufacturing industry in Indonesia has experienced growth over time, and this sector still contributes significantly to investment and investment in Indonesia. However, various global problems, such as the COVID-19 pandemic and the Russia and Ukraine war, have become threats to the sustainability of the manufacturing industry in the world, including Indonesia. One of the problems that arise is disruption of supply, manufacturing activities, and other risks that can hamper the sustainability of the manufacturing industry. Sustainable risk management can help organizations achieve sustainable goals, but sustainability and risk research studies still need to be widely carried out in Indonesia. Therefore, this study explored future research opportunities related to sustainability and risk in manufacturing. This research was conducted to find out topics related to sustainability and risk that have developed in recent years and research opportunities that can be done. The study analysis used a bibliometric analysis approach using R for Windows GUI front-end software (R4.2.2). The analysis results show that Industry 4.0 and circular economy are potential fields of study to be developed and collaborated with risk management and assessment.
Topics in robust statistical learning
Authors: Brecheteau Claire , Genetay Edouard , Mathieu Timothee , Saumard Adrien
Published: December 2023

Some recent contributions to robust inference are presented. Firstly, the classical problem of robust M-estimation of a location parameter is revisited using an optimal transport approach - with specifically designed Wasserstein-type distances - that reduces robustness to a continuity property. Secondly, a procedure of estimation of the distance function to a compact set is described, using union of balls. This methodology originates in the field of topological inference and offers as a byproduct a robust clustering method. Thirdly, a robust Lloyd-type algorithm for clustering is constructed, using a bootstrap variant of the median-of-means strategy. This algorithm comes with a robust initialization.
Random matrices and random graphs
Authors: Capitaine Mireille , Coste Simon , Gabriel Franck , Maillard Pascal , Mailler Cécile
Published: December 2023

We collect recent results on random matrices and random graphs. The topics covered are: fluctuations of the empirical measure of random matrices, finite-size effects of algorithms involving random matrices, characteristic polynomial of sparse matrices and Voronoi tesselations of split trees.
Inter-repetition Rest Impact on Percentage of Repetition Completed at
Certain Velocity Loss
Authors: Martínez-Rubio Carlos , Quidel-Catrilelbún Mauricio Elías Leandro , Baena-Raya Andrés , Rodríguez-Pérez Manuel Antonio , Pérez-Castilla Alejandro
Published: December 2023

This study examined the impact of different inter-repetition rest (IRR)
configurations (zero seconds [IRR0], three seconds [IRR3], and self-selected
less than five seconds [SSIRR]) on estimating the number of repetitions (Nrep)
and the percentage of completed repetitions relative to the maximum number of
repetitions possible to failure (%rep) after reaching 10%,
20%, and 30% velocity loss thresholds (VLT). Eighteen men
completed three sessions, each with a different IRR configuration, separated by
48–72 hours. Single sets of repetitions to momentary muscular
failure were performed against 65%, 75%, and 85% of the
one-repetition maximum during free-weight back squat and bench press exercises.
No significant differences were reported between IRR configurations for the Nrep
(P≥0.089) and %rep (P≥0.061), except
for %rep after reaching the 20–30%VLT against
65%1RM and the 10–20%VLT against 75%1RM in the
bench press exercise (P≤0.048). Additionally, both Nrep and
%rep exhibited high interindividual variability (between-subject
CV=14–79%) across the different IRR configurations. The
individual %rep-%VLT relationships were slightly stronger than
the general %rep-%VLT relationships (median
R

2
=0.914–0.971 vs.
0.698–0.900). Overall, regardless of the IRR configuration, this novel
velocity-based approach does not guarantee the same effort levels across
subjects in the free-weight back squat and bench press sets.
Change of Direction Asymmetry in Youth Elite Tennis Players: A
Longitudinal Study
Authors: D’Hondt Joachim , Chapelle Laurent
Published: December 2023

Longitudinal investigations into the development of inter-limb asymmetry in
sports are scarce. This study examined the development of change of direction
(COD) asymmetry magnitude in youth elite tennis players. Dominant (overall best
performance) and non-dominant (best performance on the other side) scores and
COD asymmetry magnitude were quantified annually (up to six years) in 323 male
and 235 female players (ages 6 to13 years). Linear mixed effects regression
models examined the development of COD performance and asymmetry magnitude
according to players’ chronological age and sex. Kappa coefficients
examined the consistency for the direction of asymmetry across test occasions.
Regardless of sex, COD performance significantly improved (p<0.001)
while COD asymmetry magnitude significantly decreased
(− 0.17±0.87% / year) with increasing
chronological age. Regardless of age, males showed significantly lower COD times
(− 0.111±0.091 s) and lower COD asymmetry
magnitude (− 0.30±1.00%) compared to females.
The slight and poor (k-value=0.02–0.00) kappa coefficients for
males and females, respectively, highlight the direction specificity of
functional asymmetry. These data show that whereas performance of the COD test
improved, the magnitude of COD asymmetry declined across chronological age in
youth tennis players.
“Brain on Fire”: Hyperperfusion as a Hallmark of Hyperammonemic Encephalopathy
Authors: Peer Sameer , Singh Paramdeep , Gupta Ritish , Bhat Priya
Published: December 2023

We describe a very rare case of acute fulminant hepatic failure as a complication of acute viral hepatitis caused by hepatitis A virus, complicated by hyperammonemic encephalopathy. The brain magnetic resonance imaging (MRI) findings were suggestive of cytotoxic edema involving bilateral cerebral hemispheres. The novel findings of hyperperfusion on arterial spin labeling perfusion MRI and hyperemic hypoxia on susceptibility weighted imaging are discussed. The patient had a rapid progression of cerebral edema and succumbed to the illness despite supportive care. Characteristic neuroimaging findings may help in the diagnosis of acute hyperammonemic encephalopathy of brain MRI, which may be useful in leading to appropriate clinical workup and diagnosis of the underlying cause of hyperammonemia. In our case, hyperammonemic encephalopathy was precipitated by fulminant hepatic failure caused by hepatitis A virus, which is a rare occurrence.
Existence and degenerate regularity of statistical solution for the 2D non-autonomous tropical climate model
Authors: Yang Hujun , Han Xiaoling , Zhao Caidi , Caraballo Tomás
Published: December 2023

In this paper, the authors investigate the probability distribution of solutions within the phase space for the non-autonomous tropical climate model in two-dimensional bounded domains. They first prove that the associated process possesses a pullback attractor and a family of invariant Borel probability measures. Then they establish that this family of invariant Borel probability measures satisfies Liouville’s theorem and is a statistical solution of the tropical climate model. Afterwards, they prove that the statistical solution possesses degenerate Lusin’s type regularity provided that the associated Grashof number is small enough.
An E-band multi-channel Doppler backscattering system on EAST
Authors: Liu S. , Zhou C. , Liu A. D. , Zhuang G. , Feng X. , Zhang J. , Zhong X. M. , Ji J. X. , Zhang S. B. , Liu H. Q. , Wang S. X. , Fan H. R. , Wang S. F. , Gao L. T. , Shi W. X. , Chen X. Y. , Liu W. D.
Published: December 2023

An E-band (60–90 GHz) multi-channel Doppler backscattering (DBS) system with X-mode polarization has been installed on the Experimental Advanced Superconducting Tokamak (EAST), which can measure the turbulence at five different radial locations simultaneously. This system can launch 31 fixed microwave frequencies in the range of 60–90 GHz with a 1 GHz interval into the plasma, and five probing signals are selected by employing a reference signal and multiple filters. During experiments, the frequency of the reference signal is tunable in the E-band, and the selected probing signals can be changed as needed without any other adjustments, which can be performed in one shot or between shots. Furthermore, the incident angle can be adjusted from −10° to 20°, and the wavenumber range is 4–25 cm−1 with a wavenumber resolution of Δk/k ≤ 0.35. Ray tracing simulations are employed to calculate the scattering locations and the perpendicular wavenumber. In this article, the hardware design, ray tracing, and initial results obtained from the EAST plasma will be presented.
An integrated hinged dual-probe for co-target fast switching imaging
Authors: Wang Kaixuan , Shi Jialin , Yang Tie , Tang Si , Yu Peng , Shi Huiyao , Zhai Shenghang , Su Chanmin , Liu Lianqing
Published: December 2023

The diversity of functional applications of atomic force microscopes is the key to the development of nanotechnology. However, the single probe configuration of the traditional atomic force microscope restricts the realization of different application requirements for the same target area of a single sample, and the replacement of the working probe will lead to the loss of the target area. Here, the design, simulation, fabrication, and application of a unique atomic force microscope dual-probe are presented, which consists of a pair of parallel cantilevers with a narrow gap and a U-shaped hinged probe base. The Integrated Hinged Dual-Probe (IHDP) is developed specifically for fast switching of probes working in limited space and independent and precise manipulation of each probe. The deflection signal sensing of two cantilevers is achieved simultaneously by a single laser beam, and the decoupled independent cantilever deflection signals do not interfere with each other. The switching of the working probe is achieved by a piezoelectric ceramic with a 2 µm stroke and U-shaped hinge structure, which is fast and does not require tedious and repetitive spatial position calibration. By measuring standard grid samples, IHDP exhibits excellent measurement and characterization capabilities. Finally, a working probe switching imaging experiment was conducted on solidified rat cardiomyocytes, and the experimental process and imaging results demonstrated the superiority of IHDP in switching probe scanning imaging of the same target area of a single sample. The two probes of IHDP can undergo arbitrary functionalization modifications, which helps achieve multidimensional information acquisition for a single target.
Effects of electrical parameters on weak shock waves induced by spark discharge
Authors: Wang Zhiyu , Chen Can , Yang Suijun , Luan Weiling , Ye Shuliang
Published: December 2023

The effects of the electrical parameters, including storage capacitance, additional inductance, charging voltage, and electrode gap, on the shock wave induced by spark discharge in gas were experimentally investigated. The results showed that the shock waves induced by spark discharge conform to the attenuation law for weak spherical shock waves outside the spark core. The shock wave amplitude is approximately proportional to the electrode gap and storage energy and decreases with increasing inductance. The effect of the charging voltage on the shock wave amplitude can be almost ignored if the storage energy is the same. The average power in the first quarter cycle of spark discharge was found to be closely related to the shock wave amplitude. An empirical equation was given between the shock wave amplitude and the average discharge power, which provides convenient access to set appropriate electrical parameters to generate shock waves of specified amplitude induced by spark discharge.
Color-selective optical edge detection enabled by thermally stimulated cholesteric liquid crystals
Authors: Chen Quan-Ming , Wang Hua-Cai , Wang Guang-Yao , Xu Chun-Ting , Tan Qing-Gui , Duan Wei , Lu Yan-Qing , Hu Wei
Published: December 2023

Optical edge detection can significantly compress the data volume and is highly pursued in imaging processing. The commonly used methods extract the optical edge information but lose the capability to distinguish colors, which is another key information for imaging. Here, a design for color-selective optical edge detection is proposed and demonstrated with a cholesteric liquid crystal q-plate. The corresponding optical edge detection exhibits a narrow reflection band characteristic due to the one-dimensional photonic crystal configuration of the cholesteric liquid crystal. The monochromatic band is thermally and reversibly tuned ∼300 nm within 5.3 °C. Color-selective optical edge detection is verified by a series of chromatic images. This work introduces a thermally responsive liquid crystal device to release the color dimension of optical edge detection, which may upgrade existing imaging processing techniques.
Obstacle-tolerant terahertz wireless link using self-healing Bessel beams
Authors: Katsuue Yu , Yabuki Ayumu , Morohashi Isao , Kanno Atsushi , Sekine Norihiko , Nakajima Junichi , Hisatake Shintaro
Published: December 2023

Wireless communications using highly directive terahertz (THz) waves exhibit lower immunity to obstructions than microwaves, limiting their applications. This study demonstrates an obstacle-tolerant THz wireless link established by a self-healing Bessel beam at 300 GHz. The Bessel beam is generated by sending a Gaussian beam through a dielectric axicon lens. Furthermore, experiments were conducted to investigate the short-range transmission (98 mm) reception characteristics with and without the dielectric cubic obstacle (7.5 λ in size) and the metallic obstacle (22 λ in length and 8 λ in width) in the Gaussian beam and self-healing Bessel beam cross sections. The maximum attenuation of the received power due to obstruction was 8.8 and 2.2 dB for the Gaussian and Bessel beams, respectively, when the dielectric obstacle is placed in the middle of the transmission path (49 mm from a transmission lens). This study further investigated the bit error rate (BER) characteristics (1 Gbps, on–off keying) with the dielectric obstacle crossing the beam cross section. When the obstacle crosses the Gaussian beam, the BER degrades as the obstacle approaches the optical axis, breaking the wireless link. In contrast, when the obstacle crosses the Bessel beam cross section, the BER is maintained at <3.8 × 10−3 (the forward error correction limit), and the wireless link is maintained. A self-healing beam, such as the Bessel beam, makes the THz wireless link more tolerant than the Gaussian beam to obstacle and expand applications for THz wireless communications.
All-wet etched high-Q optical microcavity on a silicon chip
Authors: Zhi Yanyan , Liu Li , He Yuting , Zhang Jiejun , Li Jie , Zhang Kun , Zhang Junkai , Liu Liling , Zhang Shu-Xin , Yao Jianping , Guan Bai-Ou
Published: December 2023

Optical microcavities with high quality factors can significantly enhance the intracavity power density and have become a superior platform for studying quantum electrodynamics, nonlinearities, and sensing. Minimized and compact on-chip devices require the integration of microcavities with versatile functions that can be implemented by techniques compatible with semiconductor industries. However, the silicon dry etch technique commonly used to shape silicon wafers limits the massive production of microcavities. Here, an all-wet etching technique is proposed to fabricate on-chip microcavities with the aid of photolithography. On-chip silica microdisks with quality factors of ∼105 are demonstrated, and optical modes with quality factors up to 106 are also observed. The proposed technique opens an avenue for economical, easy handling, and scalable production of on-chip microcavities using foundry-based technologies.
Spheroidization of Nd–Fe–B particles
Authors: Kim Eunjeong , Baker Alexander A. , Han Jinkyu , McCall Scott K.
Published: December 2023

Spherical powders are required for many advanced manufacturing techniques due to their inherent requirement of flowability, either within feed tubes or during powder spreading. As advanced manufacturing of magnets continues to develop, new production methods for feedstocks are also sought. Plasma spheroidization is a high-yield method to produce spherical Nd–Fe–B powders from irregularly shaped particles, with advantages including high throughput and a well-controlled size distribution. Highly spherical Nd–Fe–B powders with large scale production (i.e., kg) have been demonstrated using an inductively coupled thermal plasma system; however, the magnetic properties of the output powder display significant degradation. The coercivity was decreased from the initial 8 kOe (636 kA/m) of the as-received to 0.7 kOe (55 kA/m) for spheroidized powders. Microstructural investigation reveals 6% Nd depletion caused by the extreme temperatures of the plasma, leading to the formation of low-coercivity α-Fe and a subsequent decrease in energy product. Post-spheroidization heat treatments with Nd can partially mitigate the coercivity degradation, increasing to 1.7 kOe (135 kA/m), potentially offering a pathway toward spherical powders for a range of applications.
Electron resonant interaction with whistler-mode waves around the Earth's bow shock. II: The mapping technique
Authors: Tonoian David S. , Shi Xiaofei , Artemyev Anton V. , Zhang Xiao-Jia , Angelopoulos Vassilis
Published: December 2023

Electron resonant scattering by high-frequency electromagnetic whistler-mode waves has been proposed as a mechanism for solar wind electron scattering and pre-acceleration to energies that enable them to participate in shock drift acceleration around the Earth's bow shock. However, observed whistler-mode waves are often sufficiently intense to resonate with electrons nonlinearly, which prohibits the application of quasi-linear diffusion theory. This is the second of two accompanying papers devoted to developing a new theoretical approach for quantifying the electron distribution evolution subject to multiple resonant interactions with intense whistler-mode wave-packets. In the first paper, we described a probabilistic approach, applicable to systems with short wave-packets. For such systems, nonlinear resonant effects can be treated by diffusion theory, but with diffusion rates different from those of quasi-linear diffusion. In this paper, we generalize this approach by merging it with a mapping technique. This technique can be used to model the electron distribution evolution in the presence of significantly non-diffusive resonant scattering by intense long wave-packets. We verify our technique by comparing its predictions with results from a numerical integration approach.
Improving the neutralization of a pulsed ion beam by electron cooling and accumulation: A kinetic study
Authors: Lan Chaohui , Zhao Xinling , Ren Yaoyu , E Peng
Published: December 2023

Direct electron injection, such as through electron-emitting filaments, is usually difficult to neutralize ion beams to a very high degree. In this paper, the possibility of a pulsed ion beam achieving very high neutralization through the continuous accumulation of cold electrons is investigated using a two-dimensional particle-in-cell code. Three schemes of electron injection, namely, single-point injection, periodic point-source injection, and periodic line-source injection, are numerically studied and compared. The simulations show that even if an excess of electrons are injected, the single-point electron source is difficult to neutralize the ion beam pulse to exceed 90%, consistent with existing experiments. It is found that the spontaneous cooling mechanism of neutralizing electrons is able to improve the neutralization of the ion beam to a certain extent, but it requires a lot of time. By using a smaller injection current, the latter two injection schemes not only effectively suppress solitary waves, but more importantly, they continuously provide cold electrons that can accumulate inside the ion beam, thereby significantly improving the neutralization of the ion beam in a short period of time. The results show that periodic line-emission sources can neutralize the ion beam to over 99%, but periodic point-emission sources exhibit relatively poor neutralization performance due to their higher virtual-cathode potential. The research results can provide a reference for the design of neutralizing sources in applications that pursue very high neutralization of ion beam pulses, such as heavy ion fusion accelerators.
Cleaning effects due to shape oscillation of bubbles over a rigid boundary
Authors: Corbett Callan , Wang Qianxi , Smith Warren , Liu Wenke , Walmsley A. Damien
Published: December 2023

Recent experiments have revealed the interesting cleaning effects that take place due to the shape mode oscillation of bubbles over a rigid boundary. While a microbubble was undertaking shape oscillation moving over a bacterial biofilm, it removed the contaminants from the boundary and created a clean path through the biofilm. This demonstrated much higher cleaning efficiency than that associated with the volume oscillation of cavitation bubbles; however, the mechanism is unknown. Here, we study this phenomenon using the boundary integral method with the viscous effects modeled using the viscous potential flow theory and the compressible effects using the weakly compressible theory. The viscous stress at the rigid boundary is approximated using the boundary layer theory. We observed that the natural frequencies of shape mode oscillation decrease significantly due to the presence of the boundary. The shear stress at the boundary due to the shape oscillation of a nearby bubble is at least 20 times higher than that due to volume oscillation with the same energy and is significant only within the area directly beneath the bubble. This is explained by the notably faster decay for higher shape modes of the kinetic energy in the fluid as the distance to the center of the bubble r increases with the induced velocity of mode k decaying at a rate of O(r−(k+2)) away from the bubble. These results achieve excellent agreement with the intriguing cleaning effects first observed in the experiment and explain the mechanism behind this new highly efficient method of cleaning.
A stochastic resonance detection algorithm based on orthonormalized basis function for magnetic anomaly detection
Authors: Dai Fan , Peng Dongliang , Chen Zhikun , Li Tao , Weng Yiming , Zhuo Renxiong , Liu Baoyang
Published: December 2023

To address the problem that the performance of the detector in airborne magnetic anomaly detection (MAD) is terrible, a stochastic resonance (SR) detection algorithm based on orthonormalized basis function (OBF-SR) is proposed for MAD under low signal-to-noise ratio conditions. The signal contaminated by noise is first preprocessed by the OBF method, where the sum of the three components in the OBF space is selected as the SR system input. Then, a parallel SR system with different initial states is designed to detect the signal. Finally, the simulation analysis of MAD methods is performed to draw a comparison between the OBF-SR method, the typical SR method, and the OBF method. The results show that the OBF-SR method outperforms the SR and OBF methods in the detection probability and detection range under the same conditions.
A fast neural network surrogate model for the eigenvalues of QuaLiKiz
Authors: Fransson E. , Gillgren A. , Ho A. , Borsander J. , Lindberg O. , Rieck W. , Åqvist M. , Strand P.
Published: December 2023

We introduce a neural network surrogate model that predicts the eigenvalues for the turbulent microinstabilities, based on the gyrokinetic eigenvalue solver in QuaLiKiz. The model quickly provides information about the dominant instability for specific plasma conditions, and in addition, the eigenvalues offer a pathway for extrapolating transport fluxes. The model is trained on a 5 × 106 data points large dataset based on experimental data from discharges at the joint European torus, where each data point represents a QuaLiKiz simulation. The most accurate model was obtained when the task was split into a classification task to decide if the imaginary part of eigenvalues were stable (≤0) or not, and a regression model to calculate the eigenvalues once the classifier predicted the unstable class.
Giant anomalous Nernst effect in polycrystalline thin films of the Weyl ferromagnet Co2MnGa
Authors: Uesugi Ryota , Higo Tomoya , Nakatsuji Satoru
Published: December 2023

Recent discoveries of topological magnets have opened up diverse spintronic applications of large responses due to their unique band structures. A prominent example is the anomalous Nernst effect (ANE), a transverse magneto-thermoelectric phenomenon that produces an electromotive force orthogonal to the heat flux and magnetization. Unlike the Seebeck effect generating an electromotive force parallel to the heat flux, transverse thermoelectric properties of ANE well fit in the lateral configurations of devices fabricated through conventional thin-film fabrication processes. This feature enables distinct device applications through a simplified fabrication process, reduced production cost, extensive area coverage, and enhanced flexibility. In this study, we report the highest ANE ever recorded among all reported polycrystalline films to date by using a topological ferromagnet. In particular, we have fabricated high-quality polycrystalline thin films of the Weyl ferromagnet Co2MnGa that exhibit a large ANE of − 5.4 μV/K. By retaining a high film density, we demonstrate the sizable ANE in the films obtained using a simple fabrication process well suited for device developments. Establishing a thin-film fabrication technique capable of producing a giant ANE facilitates spintronic applications of the Weyl ferromagnet, including diverse ANE-based device applications.
Numerical study of compound drop mobility over a surface having wettability difference
Authors: Pathak Arpit , Singh Nikhil Kumar , Das Arup Kumar
Published: December 2023

Three-dimensional numerical simulations have been performed to analyze the effect of wettability difference on a compound droplet through biphilic and wettability gradient surfaces. Three distinct drop–drop configuration regimes during translation are found in both types of surfaces, as the contact angle difference on the surface is varied. Along with these advancing, rear, and central locations of core drop regimes, lens like drop–drop configuration is also realized over the biphilic surface by considering hydrophobic contact angle variation. On the biphilic surface, drop–drop configurations are also reported from simulation with different core-to-shell volume ratios and inversion of core and shell liquids.
The Simons Observatory: A fully remote controlled calibration system with a sparse wire grid for cosmic microwave background telescopes
Authors: Murata Masaaki , Nakata Hironobu , Iijima Kengo , Adachi Shunsuke , Seino Yudai , Kiuchi Kenji , Matsuda Frederick , Randall Michael J. , Arnold Kam , Galitzki Nicholas , Johnson Bradley R. , Keating Brian , Kusaka Akito , Lloyd John B. , Seibert Joseph , Silva-Feaver Maximiliano , Tajima Osamu , Terasaki Tomoki , Yamada Kyohei
Published: December 2023

For cosmic microwave background (CMB) polarization observations, calibration of detector polarization angles is essential. We have developed a fully remote controlled calibration system with a sparse wire grid that reflects linearly polarized light along the wire direction. The new feature is a remote-controlled system for regular calibration, which has not been possible in sparse wire grid calibrators in past experiments. The remote control can be achieved by two electric linear actuators that load or unload the sparse wire grid into a position centered on the optical axis of a telescope between the calibration time and CMB observation. Furthermore, the sparse wire grid can be rotated by using a motor. A rotary encoder and a gravity sensor are installed on the sparse wire grid to monitor the wire direction. They allow us to achieve detector polarization angle calibration with an expected systematic error of 0.08°. The calibration system will be installed in small-aperture telescopes at Simons Observatory.
Mo-doped Ni3S2 nanosheet arrays for boosting hydrogen evolution activity and supercapacitor energy storage
Authors: Song Xiumei , He Ranran , Guo Dongxuan , Chu Dawei , Li Hongpeng , Tan Lichao
Published: December 2023

The design and preparation of bifunctional electrode materials play a vital role in the field of energy storage and conversion. Herein, Mo-doped Ni3S2 nanosheet arrays assembled on nickel foam (named as Mo-Ni3S2) are designed through three-step continuous hydrothermal methods for enhanced hydrogen evolution reaction (HER) and supercapacitor storage characteristics. The ultrathin Mo-Ni3S2 nanosheets structure could modulate electronic structure and offer rich actives sites, thereby expediting the mobility of charge carriers and engendering a greater density of active sites. Consequently, the Mo-Ni3S2 exhibits low overpotential both in alkaline and acidic solution with the value of 53 and 65 mV at the current density of 10 mA cm−2, respectively. Meanwhile, the HER activity can be well maintained after 17 h of continuous operation at 10 mA cm−2, demonstrating its excellent stability. Furthermore, the as-prepared Mo-Ni3S2 as pseudocapacitive materials exhibits a specific capacitance of 3528 F g−1 at 1 A g−1, implying outstanding long durability with 96.5% capacity retention after 3000 charge–discharge cycles. Overall, this work provides a viable strategy for the development of transition metal-based materials as efficient bifunctional catalysts.
Tabletop extreme ultraviolet reflectometer for quantitative nanoscale reflectometry, scatterometry, and imaging
Authors: Esashi Yuka , Jenkins Nicholas W. , Shao Yunzhe , Shaw Justin M. , Park Seungbeom , Murnane Margaret M. , Kapteyn Henry C. , Tanksalvala Michael
Published: December 2023

Imaging using coherent extreme-ultraviolet (EUV) light provides exceptional capabilities for the characterization of the composition and geometry of nanostructures by probing with high spatial resolution and elemental specificity. We present a multi-modal tabletop EUV imaging reflectometer for high-fidelity metrology of nanostructures. The reflectometer is capable of measurements in three distinct modes: intensity reflectometry, scatterometry, and imaging reflectometry, where each mode addresses different nanostructure characterization challenges. We demonstrate the system’s unique ability to quantitatively and non-destructively measure the geometry and composition of nanostructures with tens of square microns field of view and sub-nanometer precision. Parameters such as surface and line edge roughness, density, nanostructure linewidth, and profile, as well as depth-resolved composition, can be quantitatively determined. The results highlight the applicability of EUV metrology to address a wide range of semiconductor and materials science challenges.
Experimental and numerical studies on the thermal nonequilibrium behaviors of CO with Ar, He, and H2
Authors: He Dong , Hong Qizhen , Li Fei , Sun Quanhua , Si Ting , Luo Xisheng
Published: December 2023

The time-dependent rotational and vibrational temperatures were measured to study the shock-heated thermal nonequilibrium behaviors of CO with Ar, He, and H2 as collision partners. Three interference-free transition lines in the fundamental vibrational band of CO were applied to the fast, in situ, and state-specific measurements. Vibrational relaxation times of CO were summarized over a temperature range of 1110–2820 K behind reflected shocks. The measured rotational temperature instantaneously reached an equilibrium state behind shock waves. The measured vibrational temperature experienced a relaxation process before reaching the equilibrium state. The measured vibrational temperature time histories were compared with predictions based on the Landau–Teller model and the state-to-state approach. The state-to-state approach treats the vibrational energy levels of CO as pseudo-species and accurately describes the detailed thermal nonequilibrium processes behind shock waves. The datasets of state-specific inelastic rate coefficients of CO–Ar, CO–He, CO–CO, and CO–H2 collisions were calculated in this study using the mixed quantum-classical method and the semiclassical forced harmonic oscillator model. The predictions based on the state-to-state approach agreed well with the measured data and nonequilibrium (non-Boltzmann) vibrational distributions were found in the post-shock regions, while the Landau–Teller model predicted slower vibrational temperature time histories than the measured data. Modifications were applied to the Millikan–White vibrational relaxation data of the CO–Ar and CO–H2 systems to improve the performance of the Landau–Teller model. In addition, the thermal nonequilibrium processes behind incident shocks, the acceleration effects of H2O on the relaxation process of CO, and the characterization of vibrational temperature were highlighted.
Study on the mechanism of water entry under the effect of floating ice based on a penalty function-based fluid–structure interaction method
Authors: Hu Xinyu , Wei Yingjie , Wang Cong , Wang Lu
Published: December 2023

Water entry in polar regions is a hot topic of mechanical dynamics. Nonetheless, the presence of floating ice can significantly influence the water entry process. In this paper, a novel two-way fluid–structure interaction (FSI) scheme based on the penalty function is proposed that is suitable for collision between objects into the water. In this scheme, the collision between the projectile and the floating ice is solved by the penalty function, and then, the collision information is transmitted to the fluid solver to solve the passive water entry process. Using dynamic models and experimental data, the accuracy of the new FSI scheme is validated. The cavity evolution and dynamic response of the floating ice colliding with the projectile are studied. During passive water entry, the development of the splash crown is inhibited. The contact line at the floating ice exhibits different movement states under different mass ratios (M). Subsequently, the passive water entry of eccentric collisions is studied, and the influence of eccentricity (Liz*) is considered. Different collision modes and contact-sliding modes occur between the floating ice and the projectile during the eccentric collision. The evolution of the cavity also appears to have asymmetric characteristics. The horizontal displacement of the floating ice influences the transition of the collision mode under the same wetted area.
Kibble–Zurek scaling of nonequilibrium phase transition in barium titanate
Authors: Baradwaj Nitish , Krishnamoorthy Aravind , Nomura Ken-ichi , Nakano Aiichiro , Kalia Rajiv K. , Vashishta Priya
Published: December 2023

Far-from-equilibrium phase transition dynamics is one of the grand challenges in modern materials science. A theoretical landmark is the Kibble–Zurek (KZ) scaling to describe the relationship between the temperature quenching rate and the resulting defect density in the vicinity of symmetry-breaking phase transformations. Despite the confirmation of the KZ scaling in ferroic perovskite materials and macroscopic simulations, its atomistic mechanisms remain elusive. Here, we demonstrate the KZ scaling using all-atom molecular dynamics simulations for a prototypical ferroelectric perovskite, barium titanate, with the scaling exponent corresponding to the theoretical prediction for rapid quenching. Simulated diffuse neutron scattering data are presented to guide future experiments.
Role of droplet viscosity on the formation of residual droplets on grooved hydrophobic surfaces
Authors: Kim Uijin , Lee Jinkee , Kim Jeong-Hyun
Published: December 2023

Surfaces with groove structures, such as butterfly wings and rice leaves, are frequently observed in nature, and the anisotropic nature of grooved structures is known to control fluid transport. Although the receding contact-line dynamics of the droplets on the grooved hydrophobic surfaces affect the behavior of droplets in motion, their depinning mechanism has not been sufficiently addressed in the literature. In this study, the receding contact-line dynamics of viscous droplets moving on inclined grooved hydrophobic surfaces were investigated using high-speed imaging. The droplet viscosity and surface-inclination angle were systematically varied to observe changes in the receding motion of droplets. The receding contact lines of each droplet contracted along the top of the groove structure and then ruptured due to discontinuity in the structure, leaving small volumes of droplets on top of the structure. Various morphological changes in the droplet were observed when it retracted along the grooves, which depended on the surface-inclination angle and viscosity of the droplet. A Rayleigh-like instability induced additional breakup of the tail of the droplet, resulting in satellite droplets being deposited on top of the grooves. The lateral size of the residual droplets deposited on the grooves increased as both the droplet viscosity and surface-inclination angle increased. The sizes of the residual droplets on tested surfaces collapsed into a single curve through a simple scaling equation developed by dimensionless analysis.
Mixed convective magnetohydrodynamic and thermally radiative flow of reactive couple stress MWCNT–Ag/C2H6O2 hybrid nanofluid in a porous vertical channel: Entropy analysis
Authors: Mushahary Pungja , Surender Ontela
Published: December 2023

This paper is concerned with the analysis of the mixed convective magnetohydrodynamic (MHD) flow of a reactive couple stress multi-walled carbon nanotube −Ag/C2H6O2 hybrid nanofluid in a porous vertical channel subjected to quadratic thermal radiation along with a uniform inclined magnetic field applied to the channel walls. The flow is driven by the pressure gradient force and the buoyancy force, which is modeled based on the nonlinear Boussinesq approximation. The temperature-dependent reaction rate of the reactant molecule is derived using the Arrhenius law. The momentum and energy equations that govern the system are modeled in consideration of slip and convective conditions. The governing equations are non-dimensionalized by applying relevant dimensionless parameters and are solved using the homotopy analysis method (HAM). To analyze the irreversibilities in the system, the entropy generation number and the Bejan number are defined. Different important physical parameters developing in the system are considered for analysis, and their effects are scrutinized on the velocity and temperature profiles along with entropy generation. The emphasis is given to the concentration of nanoparticles along with the parameters arising due to the reactions of the fluid, buoyancy force, inclined magnetic field, thermal radiation, and porous material. The analysis reveals that the velocity and temperature of the fluid lowers with a higher concentration of nanoparticles, radiation parameter, and Hartmann number, whereas develops for the higher slip parameters and inclination of the magnetic field. The entropy generation rate increases with rising slip parameters and depletes for higher nanoparticle concentration, radiation parameter, Hartmann number, and inclination angle. The irreversibility in the system remains dominant due to heat transfer with higher Frank-Kameneskii and activation energy parameters, Hartmann number, and angle of inclination.
How do crosswinds from two turbulent generators affect the aerodynamic loads of running trains at tunnel entrances?
Authors: Yue Huan , Wang Jian , Deng E , Ni Yi-Qing , Yang Wei-Chao , Liu Xin-Yuan , Tsang Cheuk-Man
Published: December 2023

In order to investigate the effect of natural turbulent crosswinds on the aerodynamic loads of a high-speed train (HST) running through a tunnel entrance of high-speed railways, the new contribution is that the changing law of the HST's aerodynamic loads under the incoming turbulence with actual turbulence integral scale is revealed when the HST running in tunnel-flat ground-tunnel scenes, based on two types of turbulence generators with size scaled up by 8 times. The train surface pressure coefficients of the numerical model are compared with the corresponding results of wind tunnel experiments to verify the computational fluid dynamics method. The primary results show that the incoming turbulent flow generated by the spire is consistent with the characteristics of the measured wind. The peak aerodynamic load coefficients of the head carriage increase 1.12–1.5 and 1.06–2.0 times, respectively, under the incoming turbulent flow by the spire and fence, compared to the incoming flow of 11.50 m/s.
Dynamics of surfactant-laden drops in shear flow by lattice Boltzmann method
Authors: Chen Zhe (Ashley) , Tsai Peichun Amy , Komrakova Alexandra
Published: December 2023

We developed and applied a diffuse interface lattice Boltzmann method for simulating immiscible liquids with soluble surfactants using a modified Ginzburg–Landau free energy functional. We first validated the approach through simulations of planar interfaces and drop equilibration in quiescent fluid. The proposed method accurately captures the phase and surfactant fields with diminishing spurious velocities of 10−6. We systemically examined the effects of capillary number, comparing viscous to surface forces, the combined effect of surfactant and viscosity ratio (λ) of the drop to the continuous phase, and the bulk surfactant load on the deformation and breakage in a shear flow. At a given capillary number (0.05<Ca<0.32), drop behavior is influenced by reduced surface tension, tip-stretching, Marangoni stresses, and surface dilution. These effects either promote (by tip-stretching) or hinder (via Marangoni stresses, surface dilution) the surfactant distribution at the interface, consequently affecting the final drop morphology. As Ca increases, the competition between the viscosity ratio and the presence of surfactant determines drops' topological changes. The presence of surfactants can overcome the effect of viscosity ratio (when 0.05≤λ≤1.7) and promote drop breakup, whereas highly viscous drops (either λ<0.05 or λ>1.7) do not break. Furthermore, high surfactant loads result in higher drop deformation and earlier drop breakup. In brief, our method successfully captures the dynamics of surfactant-laden drops in shear flow, elucidating the complex interplay between flow hydrodynamics and surfactant transport with 3D quantitative phase and surfactant concentration fields.