bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of supply chain risk mitigation framework in the digital era
Authors: M Saad Sameh , Ubeywarna Dasunika
Published: August 2024

In the context of digital transformation, supply chains contend with various challenges, and reconfiguration of supply chain design has obtained significant consideration in today’s digital era. This paper aims to reveal the adaptability of Industry 4.0 technologies to risk mitigation in supply chain design and develop a conceptual Framework. Analytic Hierarchy Process (AHP) method was used to create a conceptual risk mitigation framework and validated it through a comprehensive questionnaire collected by industrial and academic experts and academics and carried out the pairwise comparison between the main criteria and sub-criteria The contribution of this study lies in the taxonomy study, and findings revealed that digitalisation of supply chain design for risk mitigation shed light on future research. Additionally, it focuses on the potential to enhance supply networks’ efficiency and responsiveness.
Sustainable by Design: Advancing Hydrogen Fuel Cell Production through Automation
Authors: Mineo Carmelo , Infantino Ignazio , Barbera Orazio , Giacoppo Giosuè , Montinaro Nicola
Published: August 2024

The “Integrated Hydrogen Technologies” project is an extensive and comprehensive initiative funded by the Italian government to advance hydrogen fuel cell technologies for sustainable energy systems. The project outlines several research avenues to enhance fuel cell technology further and promote its integration into the global energy landscape, contributing to the acceleration of a clean, efficient, and sustainable energy transition. The project addresses critical challenges in fuel cell production, including material sustainability, production efficiency, and scalability. This article reports on the project activities targeted at the diffusion of fuel cell units. These activities have been motivated by the expected extensive use of hydrogen as an energy carrier in the transport and stationary sectors. They comprise the development of innovative processes for producing bipolar stack plates based on additive manufacturing and sustainability-by-design criteria. Furthermore, automated assembly of fuel stacks is being developed to enable high production capacities.
Enhancing robotics learning using imitation learning through visual-based behaviour cloning
Authors: Jadeja Yagna , Shafik Mahmoud , Wood Paul , Makkar Aaisha
Published: August 2024

The development of the behaviour cloning technique allows robots to mimic human experts’ behaviour by observation. The technique is mainly based on model architecture’s design and associated training mechanisms. İt is believed that such an approach will impact the importance of robotics applications in the coming future. The ongoing research presented in this paper has investigated the use of behaviour cloning with image and video data streaming to improve robot learning using imitation of human experts’ behaviour. The investigation has focused on the methodology, algorithms, and challenges associated with training robots to imitate human actions solely based on visual data inputs. An overview of the process of collecting diverse and annotated image and video datasets depicting various human actions and behaviours is presented. To provide efficient and consistent data representation, the preprocessing process includes feature extraction using convolutional neural networks (CNN) and normalization techniques. The CNN model for learning action mappings from visual inputs is described. These models’ training focuses on optimization algorithms and loss functions. A thorough examination of data quality, overfitting, and model generalization issues is addressed and presented. The research’s initial results showed the effectiveness of image and video-based behaviour cloning and how it is leading to more sophisticated and adaptive robotic systems. The limitations of the research are also discussed and presented in this paper.
Neuro – symbolic AI for materials modelling and processes design
Authors: Mekras Nikolaos , Mekra Electra , Georgiou Christos
Published: August 2024

This paper presents possibilities of combined use of Artificial Neural Networks (ANNs) with symbolic AI methods for improving the creation and the efficiency of models for materials and manufacturing processes. Besides a short presentation of one of the most basic and common ANNs architecture, which is the Multi-Layer Perceptron (MLP), and the presentation of main symbolic AI methods for knowledge representation and processing, the paper discusses their combined use and possibilities of hybrid neuro–symbolic AI applications for modelling materials and processes. This combined AI modelling approach is planned to be implemented and tested within the Horizon Europe project M2DESCO, which concerns modelling and eco-design of High Entropy Alloys’ (HEAs) coatings.
Endoscopic ultrasound‐guided versus percutaneous liver biopsy: a systematic review and meta-analysis of randomized controlled trials
Authors: Arruda do Espirito Santo Paula , Meine Gilmara Coelho , Nau Angélica Luciana , Barbosa Eduardo Cerchi , Baraldo Stefano , Lenz Luciano , Maluf-Filho Fauze
Published: August 2024

Background Percutaneous liver biopsy (PC-LB) has long been the
usual method for acquisition of liver tissue. Recently, endoscopic ultrasound-guided liver
biopsy (EUS-LB) has gained popularity as an alternative modality. We aimed to compare the
efficacy and safety of EUS-LB versus PC-LB.

Methods We systematically searched PubMed, Embase, and the
Cochrane Library databases for randomized controlled trials (RCTs) comparing EUS-LB with PC-LB
published until October 20, 2023. The primary outcome was diagnostic adequacy. Secondary
outcomes were: the number of complete portal tracts (CPTs), longest sample length (LSL), total
sample length (TSL), post-procedure pain scores, and adverse events (AEs), including overall
AEs and AEs excluding minor post-procedure symptoms. We compared binary outcomes using risk
ratios (RRs) and continuous outcomes using the mean difference (MD) or standardized mean
difference (SMD), with 95%CIs.

Results Four RCTs (258 patients) were included. The EUS-LB group
presented lower post-procedure pain scores (SMD −0.58, 95%CI −0.95 to −0.22) than the PC-LB
group. Both groups performed similarly in terms of diagnostic adequacy (RR 1.0, 95%CI 0.96 to
1.04), number of CPTs (MD 2.57, 95%CI −4.09 to 9.22), LSL (MD −2.91 mm, 95%CI −5.86 to 0.03),
TSL (MD 4.16 mm, 95%CI −10.12 to 18.45), overall AEs (RR 0.54, 95%CI 0.20 to 1.46), and AEs
excluding minor post-procedure symptoms (RR 1.65, 95%CI 0.21 to 13.02).

Conclusions This meta-analysis suggests that EUS-LB is as safe
and effective as PC-LB and is associated with lower post-procedure pain scores.

Registration on PROSPERO: CRD42023469469.
Reversible modulations of insulator–metal transition in an epitaxial VO2 film through thermal crystallization and femtosecond laser-induced-amorphization of capping Ge2Sb2Te5 layer
Authors: Ohnuki Takuto , Okimura Kunio , Liu Yiqi , Inagaki Shoya , Muraoka Yuji , Sakai Joe , Narazaki Aiko , Kuwahara Masashi
Published: August 2024

We demonstrate reversible modulation of an insulator–metal transition (IMT) of a VO2 film grown on an Al2O3 (001) substrate through crystallization and re-amorphization of a chalcogenide germanium–antimony–telluride (Ge2Sb2Te5: GST) capping layer. After succeeding in the negative shift of IMT temperature (Tr) of the VO2 film through the crystallization of the GST layer accompanied by volume reduction, we performed re-amorphization of the crystalline GST by femtosecond laser irradiation. Under the optimized conditions of laser irradiation considering the penetration depth, re-amorphization of the GST layer was fully achieved, resulting in the shift-back of Tr toward a high-temperature side. Such a reversal of IMT through the crystallization and re-amorphization of the capping GST layer was demonstrated over two cycles. It was suggested that capping GST effectively induces interfacial strain modifications in the VO2 film underneath. Although the shifts in the IMT are still small, reversible modulation of IMT shown here will be beneficial for applications of VO2 films with controllable IMT.
Numerical modeling of cavity collapse water hammer in pipeline systems: Internal mechanisms and influential factors of transient flow and secondary pressure rise dynamics
Authors: Wan Wuyi , Zhou Yu , Geng Chaolong , He Bin
Published: August 2024

This study explores the dynamics of pressure wave propagation and cavitation in pressurized pipelines during and after the rapid closure of the pipeline's end ball valve, utilizing a three-dimensional computational fluid dynamics approach with the method of characteristics, validated against Bergant and Simpson's experimental data of three degrees of cavitation. It innovatively examines transient pressure dynamics through both energy transformation and wave propagation perspectives, focusing on the phases of water column separation and coalescence, and the dynamics of flow interruption bubbles. The research delves into the detailed mechanisms of pressure wave propagation and further assesses the effects of physical factors. Key findings include: (1) As initial inlet velocities increase, cavitation starts earlier, extends further, and intensifies, with higher final volume fractions near the valve, indicating that higher velocities exacerbate cavitation. Higher inlet velocities also correlate with more intricate and expansive vortex formations. (2) Secondary pressure surges in water hammer result from the superposition of two-stage positive pressure waves. Initially, positive pressure waves within the conduit reflect twice from air pockets and the upstream boundary, remaining positive. Subsequently, they interact with secondary positive pressure waves reflected by the valve, causing a secondary pressure surge. (3) The fluid flow is laterally symmetry in the pipe cross section, except for minor local asymmetrical spikes in areas with vapor bubbles. Velocity discrepancies are notable near the pipe walls due to vapor accumulation, primarily on the upper wall due to buoyancy. This accumulation may narrow the flow area, possibly accelerating the water passing by. (4) Lower flow velocities, downward inclines, and slower valve closures diminish secondary pressure rise amplitudes in water hammer events, while reduced static heads intensify cavitation despite lessening pulse amplitudes. These findings offer valuable insights for the design and operational guidance of complex hydraulic systems during transient processes in urban water supplies.
Characterization of diamond and organic scintillation detectors utilizing radiation sources for continuous plasma operation
Authors: Iliasova M. V. , Mirfayzi S. R. , Rajput M. , Chandrasekhar K. , Fontana M. , Hoffman D. , O’Gorman T. , Kamal G. , McNamara S. A. M. , Sertoli M. , Sridhar S. , Varje J. , Wilson C. , Zakhar D. , Naylor G.
Published: August 2024

This paper provides a comprehensive study of neutron calibration methodologies, specifically highlighting the capabilities for n–γ discrimination in diamond and EJ-309, and stilbene scintillation detectors. The calibration process detailed in this study includes pulse height analysis and pulse shape discrimination, relying on the analysis of charge deposition resulting from both γ and neutron interactions. Utilizing 60Co and 252Cf radiation sources, the energy spectra of these sources are obtained. The characterized detectors were used in ST40 experiments and allowed acquiring neutron signal during a plasma shot with good agreement among diamond and scintillation detectors. Then, the diamond detector was cross-calibrated against indium activation foils placed at the same location in proximity to the ST40 during plasma shots: both detectors measured a neutron flux of ≈106 cm−2 s−1 at ≈1 m distance from the tokamak center, and the discrepancy between the diamond detector and the activation foils is ≈25%.
Transient characteristics of carrier transport in an isotopically enriched 28Si/SiGe undoped heterostructure
Authors: Wu Yu-Jui , Tsao Hung-Yu , Liao Chen-Yao , Kao Wei-Hsiang , Liu Chia-You , Li Jiun-Yun
Published: August 2024

An isotopically enriched 28Si/SiGe undoped heterostructure is a promising platform for Si-based qubits due to the long coherence time by reducing 29Si isotopes with non-zero nuclear spins. Carriers in the buried Si quantum well (QW) of the Si/SiGe heterostructures could tunnel to the oxide/Si interface, increasing charge noise and leading to charge instability. In this work, we investigate the tunneling effects on carrier distribution and transport properties in an isotopically enriched 28Si/SiGe undoped heterostructure and its transient characteristics by controlling the hold time of gate biasing under different drain biases. By holding the gate bias for a longer time, the drain is reduced since more carriers in the buried QW tunnel to the oxide interface. Furthermore, under a larger drain bias, more carriers can move across the Si/SiGe heterojunction to the oxide interface and are trapped, resulting in a stronger current reduction, which is explained by a lucky electron model.
Exploring the effect of thin film thicknesses on linear and nonlinear optical properties of MoO3 thin film
Authors: Alattar Ammar S. , Nadafan Marzieh , Khashehchi Morteza
Published: August 2024

The structural, morphological, linear, and nonlinear optical properties of MoO3 thin films deposited by thermal deposition were measured. The effect of various thicknesses of films was studied. The structural and morphological parameters of films, determined by x-ray diffraction, field emission scanning electron microscopy, and AFM images, are compared to the linear and nonlinear optical characteristics of these media. The bandgap of the prepared thin films was obtained from the diffuse reflectance spectroscopy spectra. The electron’s effective mass (me*/m0), linear refractive index (n0), and optical static and high frequency dielectric constant (ɛ0, ɛ∞) values were calculated by using the bandgap energy values. Increasing the thicknesses of thin films decreased the bandgap, increased the root mean square, and increased the size of nanoparticles and the nonlinear response of thin films. The high magnitude of n2 and β was because of MoO3 (300 nm-thickness), which were of the order of 10−5 cm2/W and 10−1 cm/W, respectively. The fluctuations in nonlinear responses observed at different thicknesses are attributed to d–d transitions and intraband scattering of equilibrium electrons influenced by laser radiation, as indicated by the nonlinearity data. The considerably elevated refractive nonlinearity values in the analyzed film materials suggest their potential for practical application in optoelectronic devices.
Mechanisms for enhanced ferroelectric properties in ultra-thin Hf0.5Zr0.5O2 film under low-temperature, long-term annealing
Authors: Tai Lu , Li Xiaopeng , Dou Xiaoyu , Sang Pengpeng , Zhan Xuepeng , Wu Jixuan , Chen Jiezhi
Published: August 2024

To gain insight into the ferroelectric mechanisms under reduced thermal budget and thickness scaling, a 4.6 nm ultra-thin ferroelectric Hf0.5Zr0.5O2 capacitor compatible with back-end-of-line (BEOL) processes (all conducted at temperatures ≤350 °C) is investigated in this work. Through O3 pretreatment at the bottom electrode (BE) interface and controlled temperature modulation of the crystalline phase, the capacitor exhibits exceptional ferroelectric (FE) properties following low-temperature (350 °C) and long-term (300 s) rapid thermal annealing (RTA). These properties include high remanent polarization (2Pr ∼ 28.53 μC/cm2), low coercive voltage (Vc ∼ 0.43 V), effective leakage suppression, robust endurance (∼1010 cycles without hard breakdown), and a desirable high dielectric constant. The main mechanisms identified include tetragonal phase nucleation under enhanced tensile stress via the oxidized BE layer (TiO2), crystalline growth controlled through RTA temperature modulation, and phase transition to the ferroelectric orthorhombic phase under electric field cycling. This research provides valuable insights for the development of BEOL-compatible nonvolatile FE memories.
Spin-polarized second-order nonlinear Hall effect in 8-Pmmn monolayer borophene
Authors: Yar Abdullah , Sumayya
Published: August 2024

The second-order nonlinear Hall effect in 8-Pmmn monolayer borophene under the influence of an out-of-plane electric field and intrinsic spin–orbit interaction is reported. This unconventional response sensitive to the breaking of discrete and crystal symmetries can be tuned by the applied electric field, which can vary the bandgap induced by spin–orbit coupling. It is described by a Hall conductivity tensor that depends quadratically on the applied electric field. We find that the nonlinear Hall effect strongly depends on the spin polarization. In particular, it exhibits out of the phase character for spin-up and spin-down states. Remarkably, it undergoes a phase flip in the spin-up state at a large out-of-plane electric field that generates a staggered sublattice potential greater than the spin–orbit interaction strength. It is shown that the nonlinear Hall effect in the system originates from the broken inversion symmetry that plays an indispensable role in developing finite Berry curvature and its relevant dipole moment. It is found that at zero temperature, the nonlinear Hall response is maximal when the Fermi energy is twice the bandgap parameter and vanishes at large Fermi energies. Notably, the peak of nonlinear Hall response shifts to lower Fermi energies at finite temperature.
Modeling the evaporation and drying of two-component slurry droplets
Authors: Bhattacharjee Anurag , Gnanaskandan Aswin
Published: August 2024

In this paper, we present a mathematical model and numerical simulation for the evaporation and drying of a liquid droplet containing suspended solids, relevant to processes such as spray drying and spray pyrolysis in the food and pharmaceutical industries. The model comprises three stages: first is the evaporation of the liquid droplet consisting of solid particles, followed by the second stage starting with the formation of a porous crust around a wet-core region and, finally, the third stage with sensible heating of the dry particle. Using a finite difference method with a moving grid, we account for the moving interface between the crust and wet core. Our model incorporates spatial temperature variations and is validated against experimental data on colloidal silica droplet drying, showing good agreement. We examine model assumptions and analyze the impact of drying conditions on drying rate and final particle morphology. Along with the temperature and velocity of the drying gas, we also find that the shape of suspended solid particles inside the droplet and assuming continuum flow of vapor through the crust influence drying quality. Finally, we develop a regime map to predict whether the final particle will be solid or hollow based on operating conditions.
The interaction between water droplets and superhydrophobic holes: Detachment and penetration
Authors: Tang Yunqi , Cai Chujiang , Zhou Xin , Qiao Shuai , Pan Chong , Liu Yanpeng
Published: August 2024

Water droplets of varying volumes exhibit distinct behaviors at the tip of a needle under the influence of gravitational force: larger droplets fall from the needle tip, while smaller droplets adhere to the needle tip. By integrating a superhydrophobic hole, which allows the needle to pass through but hinders droplets' passage, a method to allow smaller droplets to fall from the needle was evaluated. The interaction between water droplets and a superhydrophobic hole was studied experimentally, and two phenomena were observed: either the droplet detached from the needle tip or the needle pulled it through the superhydrophobic hole. A critical detachment volume Vcrid0,D, dependent on the needle diameter d0 and the superhydrophobic hole diameter D, determines droplet behavior. When the volume of the droplet Vdroplet>Vcrid0,D, the droplet detaches from the needle tip. When the Vdroplet<Vcrid0,D, the droplet penetrates through the superhydrophobic hole. The results show that the critical detachment volume Vcrid0,D increases with an increase in d0 for a given superhydrophobic hole and with an increase in D for a given needle. To enable a 0.25 μl droplet to fall from a 32G needle, a superhydrophobic hole of 0.48 mm diameter was employed. Furthermore, a mechanical model based on force equilibrium was developed to describe the interaction between water droplets and a superhydrophobic hole.
Array of resonant-type spin-torque diodes as a broadband rectifier: Numerical studies
Authors: Semenova Elena K. , Berkov Dmitry
Published: August 2024

In this paper, we propose a new approach for constructing broadband rectifiers from resonant-type in-plane spin-torque diodes (STDs). The intrinsic bandwidth of such STDs constrained by the ferromagnetic resonance linewidth of the corresponding magnetic tunnel junction’s is relatively narrow, which is a significant limitation. To address this issue, we propose the implementation of an array of these STDs, each with a distinct resonance frequency. By ensuring that the frequency difference between adjacent STDs is smaller than their individual bandwidths, we achieve a device capable of rectifying signals over a much wider frequency range. To verify the effectiveness of our approach, we have performed analytical calculations based on the Landau–Lifshitz–Gilbert equation with the Slonczewski term, complemented by macrospin modeling and full-scale micromagnetic simulations to account for thermal fluctuations and local magnetization inhomogeneities. Our results demonstrate that an STD array can effectively function as a broadband energy harvester, maintaining near-constant rectification efficiency across a broad frequency range. This research establishes the groundwork for the development of broadband energy harvesters based on STD arrays, with potential applications in various fields requiring efficient energy conversion across a wide frequency spectrum.
Going it alone: observations of solitary roosting in two Australian flying-foxes (Pteropus alecto and P. poliocephalus)
Authors: Mo Matthew
Published: August 2024

Unlike some flying-fox species that exhibit solitary roosting, all flying-fox species of the Australian mainland are strongly colonial, though some extent of solitary roosting in these species is anecdotally known. This note reports on five accounts of solitary roosting in black flying-foxes (Pteropus alecto) and grey-headed flying-foxes (Pteropus poliocephalus), herein referred to as 'singletons'. These accounts are potentially the first published detailed observations of singletons in Australian flying-foxes outside of visible periods of food shortages. In particular, one account involved solitary roosting recorded over multiple days. The frequency and extent of singletons in Australian flying-foxes remain completely unknown. In terms of deriving population sizes in these species from counts at communal roosts, these individuals represent an addition to those estimates.
Diffusion barriers imposed by tissue topology shape Hedgehog morphogen gradients
Authors: Schlissel Gavin , Meziane Miram , Narducci Domenic , Hansen Anders S. , Li Pulin
Published: August 2024

Animals use a small number of morphogens to pattern tissues, but it is unclear how evolution modulates morphogen signaling range to match tissues of varying sizes. Here, we used single-molecule imaging in reconstituted morphogen gradients and in tissue explants to determine that Hedgehog diffused extracellularly as a monomer, and rapidly transitioned between membrane-confined and -unconfined states. Unexpectedly, the vertebrate-specific protein SCUBE1 expanded Hedgehog gradients by accelerating the transition rates between states without affecting the relative abundance of molecules in each state. This observation could not be explained under existing models of morphogen diffusion. Instead, we developed a topology-limited diffusion model in which cell–cell gaps create diffusion barriers, which morphogens can only overcome by passing through a membrane-unconfined state. Under this model, SCUBE1 promoted Hedgehog secretion and diffusion by allowing it to transiently overcome diffusion barriers. This multiscale understanding of morphogen gradient formation unified prior models and identified knobs that nature can use to tune morphogen gradient sizes across tissues and organisms.
Parallel ecological and evolutionary responses to selection in a natural bacterial community
Authors: Hesse Elze , Luján Adela M. , O’Brien Siobhan , Newbury Arthur , McAvoy Terence , Soria Pascual Jesica , Bayer Florian , Hodgson David J. , Buckling Angus
Published: August 2024

Evolution can occur over ecological timescales, suggesting a potentially important role for rapid evolution in shaping community trait distributions. However, evidence of concordant eco-evolutionary dynamics often comes from in vitro studies of highly simplified communities, and measures of ecological and evolutionary dynamics are rarely directly comparable. Here, we quantified how ecological species sorting and rapid evolution simultaneously shape community trait distributions by tracking within- and between-species changes in a key trait in a complex bacterial community. We focused on the production of siderophores; bacteria use these costly secreted metabolites to scavenge poorly soluble iron and to detoxify environments polluted with toxic nonferrous metals. We found that responses to copper-imposed selection within and between species were ultimately the same—intermediate siderophore levels were favored—and occurred over similar timescales. Despite being a social trait, this level of siderophore production was selected regardless of whether species evolved in isolation or in a community context. Our study suggests that evolutionary selection can play a pivotal role in shaping community trait distributions within natural, highly complex, bacterial communities. Furthermore, trait evolution may not always be qualitatively affected by interactions with other community members.
Equivocation in media communication
Authors: Alroumi Abdulrahman
Published: August 2024

This paper examines equivocation in Arabic and global interviews using interviews with Saudi politician Adel Al-Jubeir as a case study. The study has three main objectives: to assess the applicability of existing frameworks for coding responses in Arabic interviews, to explore the potential discrepancy in question design between Arabic and global interviews and its potential impact on equivocation, and to identify the most frequently recurring responses in these interviews. Rasiah’s (2010) framework is employed to analyse equivocation and coding responses. The dataset includes 2 hours and 45 minutes of Arabic interviews and an equal duration of global interviews. The findings indicate the effectiveness of the proposed frameworks in coding responses in Arabic interviews. Likewise, they show that Arabic interviewers adopt a less adversarial questioning style compared to their global counterparts, and that aggressive questioning contributes to higher equivocation rates. Furthermore, the coded responses vary between the two interview settings.
Setting boundaries between crime and rights
Authors: Cheng Le , Zhu Xiaobin
Published: August 2024

In 2022, the U.S. Supreme Court’s ruling on Dobbs v. Jackson overturned two precedents, thus
ending American women’s 50-year-old constitutional right to abortion. Drawing on Van Leeuwen’s legitimation framework and Labov’s
model of narrative structure, this study focuses on how justices (de)legitimate abortion rights in contrasting narratives in
Dobbs through authorization, moral evaluation, rationalization, and mythopoesis. Specifically, we propose a
theoretical model of judicial narrative strata to deconstruct the language of justices and explain how judicial narratives set
boundaries between two different moral economies around abortion and realize the transformation of a conceived right into a
punishable crime. Furthermore, this study suggests that in the post-Dobbs era, the justices’ narrative
reconfiguration of moral boundaries may turn into social boundaries and trigger more gender segregation, which might also have
theoretical and practical implications for legislation and judicial practices in other jurisdictions.
Gradient conformal stationarity and the CMC condition in LRS spacetimes
Authors: Amery G , S Dunsby P K , Sherif A M
Published: August 2024

We study the existence of gradient conformal Killing vectors (CKVs) in the class of locally rotationally symmetric (LRS) spacetimes which generalizes spherically symmetric spacetimes, and investigate some implications for the evolutionary character of marginally outer trapped surfaces. We first study existence of gradient CKVs via the obtention of a relationship between the Ricci curvature and the gradient of the divergence of the CKV. This provides an alternative set of equations, for which the integrability condition is obtained, to analyze the existence of gradient CKVs. A uniqueness result is obtained in the case of perfect fluids, where it is demonstrated that the Robertson–Walker solution is the unique perfect fluid solution with a nonvanishing pressure, admitting a timelike gradient CKV. The constant mean curvature condition for LRS spacetimes is also obtained, characterized by three distinct conditions which are specified by a set of three scalars. Linear combinations of these scalars, whose vanishing define the constant mean curvature condition, turn out to be related to the evolutions of null expansions of 2-spheres along their null normal directions. As such, some implications for the existence of black holes and the character of the associated horizons are obtained. It is further shown that dynamical black holes of increasing area, with a non-vanishing heat flux across the horizon, will be in equilibrium, with respect to the frame of the conformal observers.
Research on gear flank surface defect detection of automotive transmissions based on improved YOLOv8
Authors: Yuan Haibing , Yang Yiyang , Guo Bingqing , Zhao Fengsheng , Zhang Di , Yang Shuai
Published: August 2024

In industrial production, the manufacturing processes may introduce defects on the gear flanks of transmission gears, potentially leading to premature failures and diminished performance. The early detection and precise assessment of surface defects on transmission gear flanks are critical for maintaining the safety, reliability, and cost-effectiveness of automobiles. At present, the principal approach for identifying defects on automotive transmission gear flanks predominantly involves manual visual inspections, supplemented by fluorescent magnetic particle testing. However, this approach suffers from low accuracy and efficiency. Consequently, this paper presents a defect detection algorithm that leverages an enhanced YOLOv8 model to facilitate the efficient detection of surface defects on automotive transmission gear flanks. Initially, the collected image data underwent data augmentation and exploratory analysis, which informed targeted enhancements. Subsequently, the YOLOv8 algorithm was thoroughly examined. The spatial pyramid pooling layer efficient architecture was incorporated into the backbone network, and the Deformable Convolutional Networks v4 module was integrated to boost the model’s capability in detecting irregular defects. In the neck network, the BiFormer attention mechanism was implemented to enhance detection performance for small-scale defects. Moreover, the newly developed modified adaptive structure feature fusion MASFF_Head structure was adopted as the detection head to augment detection efficacy for multi-scale defects. Additionally, the bounding box loss function was substituted with the Wise-Intersection over Union (WIoU) loss function to improve performance on low-quality samples. Experimental results demonstrated that the mean average precision (mAP@0.5) of the refined YOLOv8 network model reached 86.1%, marking a 2.8% increase over the original model and significantly boosting detection accuracy. When compared to other deep learning models, the enhanced YOLOv8 model exhibits considerable superiority in terms of detection precision and efficiency. The precision (P) value and recall (R) value achieved were 82.9% and 80.8%, respectively, with a detection time of 21.6 milliseconds. This underscores the method’s effectiveness and reliability in detecting automotive transmission gear defects, underscoring its pivotal role in facilitating automated detection processes on industrial production lines.
Model modification and influence of edge effect on effective area of giant electro-rheological polishing using plate electrodes
Authors: Ai Haihong , Ren Pingfa , Wang Kun , Song Tianqi , Wang Zhanshan
Published: August 2024

Giant electro-rheological polishing (GERP) is recognized as an innovative ultra-precision machining technology with significant potential. However, the pronounced edge effect within the GERP’s polishing gap can introduce errors in calculating the effective area and designing the electrode structure. This, in turn, may lead to under-polishing and an increased risk of insulation breakdown. In this study, COMSOL was employed to investigate the electric field distribution characteristics within the polishing gap. This exploration aimed to refine the calculation model of the effective area, optimize the plate electrodes’ structure and size, and diminish the likelihood of insulation breakdown. Through systematic finite element simulations, the impact of polishing voltage, inter-electrode gap, and plate length on the edge effect was thoroughly analyzed to ascertain its influence range. The simulation findings revealed that, while maintaining a constant inter-electrode gap for the tool electrode, variations in the polishing gap, polishing voltage, and plate length within specific ranges resulted in an edge effect influence range of approximately 1 mm. Moreover, when the machining gap, polishing voltage, and plate length remained unchanged, the edge effect influence range increased proportionally with the electrode gap within a specific range, approximately equivalent to the size of the electrode gap. Experimental validation of the giant electro-rheological effect confirmed the existence and influence range of the edge effect, aligning with the finite element simulation results. Ultimately, modifications to the calculation model of the effective area were proposed, along with a solution to optimize the electrode size and structure, with the objective of reducing the probability of insulation breakdown. In practical applications, this work can provide a valuable reference for electrode structure design, insulation breakdown improvement and parameter selection.
A tunable dual-narrowband HTS filter using coding superconducting metamaterials aided by grey wolf algorithm
Authors: Wang Ruolin , Liu Haiwen , Kuang Jiaxin , Tian Hongliang , Wang Sidong
Published: August 2024

The design of tunable dual-narrowband high-temperature superconducting (HTS) filter based on coding superconducting metamaterials aided by grey wolf algorithm (GWA) is proposed in this paper. By virtue of the characteristics of right/left-handed bands and scale of deep sub-wavelength, the tunable metamaterials unit loaded with varactor is designed, with coupling types of coding pairs further studied. A tunable sixth-order HTS filter circuit is then constructed, whose layout is effectively optimized by newly developed GWA method. Simulated frequency responses demonstrate that the center frequencies of dual-band respectively locate at 170.1–177.2 MHz (Band I) and 185.2–194.1 MHz (Band II), with 3 dB fractional bandwidth of 0.65%–0.61% and 0.62%–0.57%. The deeply miniaturized circuit size is 0.037 × 0.046 λ2g, and the close-to-band rejection level reaches 80 dB. Experimental results of fabricated prototype measured at 70 K validate the feasibility of described design method for high order tunable HTS filter.
Field theory of active Brownian particles with dry friction
Authors: Zhang Ziluo , Yuan Shurui , Komura Shigeyuki
Published: August 2024

We present a field theoretic approach to capture the motion of a particle with dry friction for one- and two-dimensional (2D) diffusive particles, and further expand the framework for 2D active Brownian particles. Starting with the Fokker–Planck equation and introducing the Hermite polynomials as the corresponding eigen-functions, we obtain the actions and propagators. Using a perturbation expansion, we calculate the effective diffusion coefficient in the presence of both wet and dry frictions in a perturbative way via the Green–Kubo relation. We further compare the analytical result with the numerical simulation. Our result can be used to estimate the values of dry friction coefficient in experiments.
Condensate formation in a chiral lattice gas
Authors: Wang Boyi , Jülicher Frank , Pietzonka Patrick
Published: August 2024

We investigate the formation of condensates in a binary lattice gas in the presence of chiral interactions. These interactions differ between a given microscopic configuration and its mirror image. We consider a two-dimensional lattice gas with nearest-neighbour interactions, to which we add interactions involving favoured local structures (FLSs) that are chiral. We focus on FLSs that have the shape of the letter L and explore condensate formation through simulations and analytical calculations. At low temperature, this model can exhibit four different phases that are characterised by different periodic tiling patterns, depending on the strength of interactions and the chemical potential. When particle numbers are conserved, some of these phases can coexist. We analyse the structure and surface tension of interfaces between coexisting phases and determine the shapes of minimal free energy of crystalline condensates. We show that these shapes can be quadrilaterals or octagons of different orientation and symmetry.
Fisheye Night Sky Imager: A Calibrated Tool to Measure Night Sky Brightness
Authors: Hung Li-Wei , White Jeremy , Joyce Damon , Anderson Sharolyn J , Banet Benjamin
Published: August 2024

The Night Skies Team of the U.S. National Park Service (NPS) has developed a new camera system equipped with a fisheye lens to measure night sky brightness. This NPS Fisheye Night Sky Imager comprises a back-illuminated Sony IMX455 CMOS sensor housed in the ZWO ASI6200MM camera, a Johnson V filter, and a Sigma 8 mm F3.5 fisheye lens. All of the components are commercially available. The fisheye lens allows us to capture the entire sky in a single frame. The wide-angle view also introduces calibration challenges. To address this, we have customized tools and devised innovative methods for calibrating the system, including flat-field correction, pixel scale determination, and field of view characterization. Additionally, we use standard stars for precise positional and photometric calibration. Furthermore, we create an open-source Python pipeline to process these fisheye images and leverage Git and GitHub for source code version control and distribution. The resulting images provide a positionally and brightness-calibrated fisheye view of the night sky, with a photometric calibration uncertainty of 0.12 mag. When comparing our Fisheye Night Sky Imager measurements to images taken with other calibrated systems, we reliably achieve consistent results under both dark and bright skies. Our Fisheye Night Sky Imager not only enables rapid assessment of sky quality but also supports the feasibility of establishing permanent monitoring locations. Recognizing that the natural dark sky is a critical element for natural, cultural, educational, and visitor experiences, this new camera system enhances our ability to assess resource conditions and fulfill the NPS mission of conserving resources unimpaired for the enjoyment of this and future generations.
An emf-temperature reference function for Pt–20%Rh versus Pt thermocouples in the temperature range of 0 °C to 1100 °C
Authors: Edler F , Ederer P , Huang K
Published: August 2024

An electromotive force–temperature reference function for thermocouples made of platinum–20%rhodium versus platinum (Pt–20%Rh/Pt) was determined for the temperature range from 0 °C to 1100 °C. Three Pt–20%Rh/Pt thermocouples were constructed at the Physikalisch-Technische Bundesanstalt (PTB) and were compared with standard platinum resistance thermometers, an Au/Pt thermocouple and a Pt/Pd thermocouple, which were all calibrated at fixed points of the International Temperature Scale of 1990 (ITS-90). The comparison measurements were performed in stirred liquid baths in the range from 0 °C to 545 °C, in a sodium heat pipe from 560 °C to 980 °C, and in a five-zone furnace at temperatures between 1000 °C and 1100 °C. Furthermore, the Pt–20%Rh/Pt thermocouples were calibrated at fixed points of the ITS-90. The PTB reference function based on two of the three Pt–20%Rh/Pt thermocouples has an expanded measurement uncertainty of 0.25 K in the temperature range from 0 °C to 1100 °C.
Community perception towards sustainable urban stormwater management practices: a case study in Thu Duc City, Vietnam
Authors: Hoang Giang Ngo Ngoc , Xuan Quang Chau Nguyen , Bao Ngoc Tran Huynh
Published: August 2024

Sustainable urban Stormwater Management (SSM) is currently widely implemented globally to support urban flood management efforts. It is commonly known by terms such as Green Infrastructure (GI), Best Management Practice (BMP), Sustainable Urban Drainage System (SUDS) or Low Impact Development (LID). However, in Vietnam, these approaches are still relatively new and have not been widely adopted due to various barriers, including community perception. Therefore, this study conducted a preliminary social survey in the Thu Duc City area to gain a deeper understanding of perspectives, knowledge, and support for SSM practices. The results showed that among the surveyed residents, 78% favored a centralized stormwater management manner (e.g., retention/detention ponds,…), 51% preferred a decentralized manner (e.g., rain gardens, infiltration trenches,…) and 45% considered household-level practices (e.g., green roofs, rain barrels,…). Additionally, when asked about financial contributions towards implementing these practices, approximately 70% did not support the idea, and 50% believed it was the government’s responsibility. The research findings highlight the diversity in urban residents’ perceptions and opinions regarding stormwater management. This study provides essential foundational information for the development of policies and strategies to effectively promote SSM practices, aiming to mitigate urban flooding and contribute to environmental protection.
Landscape Design of ”Tjikoepa Inn” Agrotourism in Sukanagara District, Cianjur Regency
Authors: Ihsan A A , Gunawan A
Published: August 2024

The population growth rate of Cianjur Regency, Indonesia, continues to increase with an annual growth rate of 1.26%. This population growth has consequences to the need of land requirement for settlements, so that the conversion of agricultural land is inevitable. To reduce the rate of the conversion, it can be pursued through the utilization of less productive land into multifunctional productive land, for example by building agro-tourism. One of the lands that has not been optimally utilized is a 3 hectare agricultural land owned by Tjikoepa Inn in Sukanagara, Cianjur Regency. The purpose of this research is to design the less productive of agricultural land into an agrotourism landscape that can meet the lodging and tourism needs of Cianjur Regency. The method used in this research is the description method through an approach of program-based landscape design. Agricultural activities and commodities are determined by the land owner. The design concept adopted is modern integrated agricultural tourism by considering low external input and sustainable agriculture (LEISA) that can maximize the potential of integrated farming that is educative and provides a more inspiring and fun experience for visitors ranging from children to adults. The space formed includes service area, culinary tourism area, agricultural tourism area (horticulture, plantations, livestock, and fisheries), outbound area, glamping area, conservation area, and place of view point. Visitors are pampered with all their senses along the way starting from the parking lot upto the highest level at the place of view point.
Urban Sprawl Analysis Using Landscape Metrics in Chiba Prefecture, Japan from 1990-2021
Authors: Aurora Ruth Mevianna , Furuya Katsunori
Published: August 2024

Urban sprawl, characterized by unregulated development on the outskirts of urban areas, leads to agricultural land loss, reduced biodiversity, and environmental issues. The study employs landscape metrics to analyze the spatial patterns and effects of urban sprawl by measuring the fragmentation and structure of urban areas in Chiba Prefecture, Japan. The research employs data collected from Landsat imagery 5 (1990) and 8 (2021) and utilizes the Google Earth Engine platform for spatial and temporal analysis. The Land Use Land Cover (LULC) assessment reveals the transformation of Chiba’s landscape from 1990 to 2021, with urban areas expanding significantly and vegetation decreasing. The analysis using 8 selected landscape metrics highlights the varying degrees of urban sprawl across Chiba Prefecture. Cities near Tokyo show higher levels of sprawl, while some areas outside the edge experience growing development. Notably, there is a trend of increasing urban sprawl toward the edge. As Chiba Prefecture faces challenges from an aging population, the findings emphasize the need for controlled urban development to mitigate the negative impacts of sprawl and the importance of sustainable urban planning especially towards the edge area to ensure a balance between development and environmental preservation.
Contributions of Corporate Green Space In Conserving Plant Diversity and Its Potential Usefulness: Case Study Wikasatrian Pusat Kepemimpinan
Authors: Kurniawati F , Muhaimin M , Hidayat I W , Warsono T , Widiantoro T C , Kholis M , Sunandar D , Rustandi U
Published: August 2024

Wikasatrian Pusat Kepemimpinan, under the PT Wijaya Karya Persero Tbk management, applies sustainability principles in managing its landscape. Wikasatrian Forest is a green-forested space in the Wikasatrian that is allowed to grow and develop naturally with no or lesser management. A study on plant diversity was conducted to strengthen its conservation value. The study aimed to identify the plant variety of the Wikasatrian Forest, assess the population, and its potential usefulness for people and nature in the landscape and other needs. Data were collected using the line transect method and quadrats analysis of 10 x 10 m squares for trees, 5 x 5 m squares for saplings, and 1 x 1 m squares for ground covers, with six plots of 10 x 100 m squares, in line with the forest track. Results showed that 26 tree species from 20 families were found. On all structure levels, the Shannon’s diversity index (H) was moderate (2.53 – 2.78), and the species evenness index (E) was high (0.7 – 0.82). These showed that this area has a good ecosystem balance with diverse plant species. Most species have multiple potential uses, which are used for medicinal purposes (14) and food sources (10). Some are for materials (9) and environmental improvement (6).