bluuebunny/crossref_metadata_2025_split huggingface dataset:
A review of non-Lorentz invariant variable speed of light theories
Authors: Bileska Mila 
Published: July 2024

Abstract
This work re-derives and discusses non-Lorentz invariant variable speed of light (VSL) theories in the context of cosmological problems. Following a thorough introduction to the subject, an explicit solution demonstrating a possible dependence of the speed of light on the cosmological scale factor is presented and analyzed. The parameters of the initial ansatz,

c
(
t
)
=

c
0

a
n

, are constrained by requiring the VSL formulation to be a solution to the flatness and horizon problems. The theoretical section is concluded with a derivation of the change of entropy in a VSL Universe. Even though such findings imply that the speed of light can vary only in non-flat spacetime, an adapted approach using the Generalized Second Law of Thermodynamics is shown to loosen this restriction. Further, in the experimental section, recent evidence for a temporally varying fine structure constant at

≈

4
σ

significance is presented as a potential test for the VSL hypothesis. Overall, this work introduces and evaluates many aspects of non-Lorentz invariant VSL theories whilst encouraging future research and serving as a largely self-sufficient comprehensive overview paper.
FourSTUblack holes shadows
Authors: Sekhmani Yassine , Jyoti Gogoi Dhruba , Myrzakulov Ratbay , Gaetano Luciano Giuseppe , Rayimbaev Javlon 
Published: July 2024

AbstractIn this work, we examine the optical behaviors and thermodynamic phase structures using shadow analysis for fourSTUblack holes. The study is conducted for four cases of charge configurations on the parameter spaceM(q1,q2,q3,q4). As a matter of fact, both the electric charge as a parameter and the parameter spaceM(q1,q2,q3,q4)affect the geometry of the black hole shadow, particularly the size of the shadow. We also introduce a constraint on the charge of the black hole from the observational results of the M87⋆and Sgr A⋆shadow. Furthermore, we show that the electric charge and the parameter spaceM(q1,q2,q3,q4)have a non-trivial impact on the variation of the energy emission rate. Interestingly enough, we find novel scenarios in which the evaporation is slower, which causes the lifetime of the black holes to be considerably elongated. On the other side, the phase structure of fourSTUblack holes is explored for two cases of electric charge configuration. The findings show a perfect correlation between the shadow and event horizon radii. This correlation is, in fact, helpful in discovering the phase transition in terms of the shadow radius. In addition, the microstructure is being analyzed in terms of shadow analysis, providing similar behavior to the ordinary situation of the Ruppeiner formalism.
Measures of solid-state material and powder bed absorptivity in the visible and near IR spectrum with new small homemade integrative spheres
Authors: Nordet Guillaume , Kromer Robin , Arvieu Corinne , Lacoste Eric 
Published: July 2024

Abstract
The absorptivity is a major parameter in laser-matter interaction. It can be measured by different methods (thermal or optical). The already known integrating sphere method is generally used with spheres whose choice of dimensions and architecture is not discussed in the literature. The influence of the parameters of the sphere (size of the sphere, position of the photodiode on the sphere, distance of the photodiode from the sphere, opening of the passage of the laser, distance from sample to the sphere, presence of a baffle in front of the photodiode, sample angle, coating materials) was tested with a mirror of known reflectivity. This study has demonstrated that it is possible to use small integrating spheres for absorptivity measurements. These spheres are home-made by additive manufacturing from a polymer, with the inner walls coated with BaSO4. The optimum experimental conditions for these small spheres are defined, particularly the angle sample. The absorptivity of various materials in the solid state and powder bed was measured for four wavelengths. These measurements were carried out for three sizes of spheres and confirmed the literature results (for example, the absorptivity is measured at 80% for copper at blue wavelength). This small sphere will be adapted to in-situ measurement, particularly in the Laser Powder Bed Fusion process whatever wavelength, particularly new green or blue laser sources, and material.
Design of hexapod robot equipped with omnidirectional vision sensor for defect inspection of pipeline’s inner surface
Authors: Guo Zhanshe , Liu Yang , Zhou Fuqiang , Zhang Peiran , Song Zhipeng , Tan Haishu 
Published: July 2024

Abstract
Defect detection of inner surface of precision pipes is a crucial aspect of ensuring production safety. Currently, pipeline defect detection primarily relies on recording video for manual recognition, with urgent need to improve automation, quantification and accuracy. This paper presents a hexapod in-pipe robot with carrying capacity designed to transport the omnidirectional vision sensor to specified location within unreachable pipelines. The feasibility of the robot’s mechanical design and sensor load-carrying module is analyzed using theory calculations, motion simulations and finite element method. To address the challenges of small pixel ratio and weak background changes in panoramic images, a tiny defect segmentor based on ResNet is proposed for detecting tiny defects on the inner surface of pipelines. The hardware and software systems are implemented, and the motion performance of the pipeline robot is validated through experiments. The results demonstrate that the robot achieves stable movement at a speed of over 0.1 m s−1 and can adapt to pipe diameter ranging from of 110 to 130 mm. The novelty of the robot lies in providing stable control of the loaded vision sensor, with control precision of the rotation angle and the displacement recorded at 1.84% and 0.87%, respectively. Furthermore, the proposed method achieves a detection accuracy of 95.67% for tiny defects with a diameter less than 3 mm and provides defect location information. This pipeline robot serves as an essential reference for development of in-pipe 3D vision inspection system.
Fast and accurate phase processing in off-axis digital holography combining adaptive spatial filtering and an embedded GPU platform
Authors: Bai Hongyi , Li Liyang , Sun Laijun , Liu Zeru , Chen Jia , Min Rui 
Published: July 2024

Abstract
Parallel-phase processing enables rapid phase extraction from off-axis digital holograms. To achieve fast and accurate results, the phase reconstruction processes were parallelized using improved filter algorithms and optimized programming strategies. First, an adaptive filtering method based on the Chan–Vese (CV) model which better suits parallelism was designed to extract the +1 term spectrum. We selected suitable computer unified device architecture libraries according to the characteristics of the key phase reconstruction steps. Acceleration technologies, such as virtual memory and shared memory, were used to improve the computational efficiency. Furthermore, we combined an improved 4f optical imaging system with an embedded graphic processing unit (GPU) platform to design a low-cost phase reconstruction system for off-axis digital holography. To verify the feasibility of our method, the reconstructed quality of the CV filtering method was estimated, and the run times of phase retrieval on the central processing unit and embedded GPU were compared for off-axis holograms with different pixel sizes. Additionally, the dynamic fluctuation phase maps of water droplet evaporation were retrieved to demonstrate the real-time capability of the method.
Effect of Bi content and temperature on the shear mechanical properties of Fe-Bi nanocomposites: a molecular dynamics study
Authors: Li Pan , Wang Fazhan , Li Guangyuan , Fan Yuan , Chen Zhanwen , Liu Menghui , Wu Hong 
Published: July 2024

Abstract
In this study, the effects of Bi content and temperature on the mechanical properties of Fe–Bi nanocomposites were investigated using molecular dynamics simulation. The research reveals that the nanocomposite’s shear strength reaches a peak of 3.785 GPa at a Bi content of 0.15%, attributed to the impediment of dislocation movement by twin boundaries during shearing, resulting in a dynamic ‘Hall–Petch’ effect and exceptional shear performance of the material. The abundant twinning induced around Bi phase inclusions introduces orientational disparities within the crystal, leading to grain misalignments, with dislocations in the grains slipping near the twin boundaries. In the nanocomposites, <100> dislocations merely act as initial sites for reactions, reducing their impact on the material’s strength and fracture behavior. The maximum stress decreases with increasing temperature while the magnitude of atomic transformations increases. The proportion of atoms at grain boundaries is higher at higher temperatures, and the arrangement of atoms at grain boundaries is more complex. At a temperature of 100 K, the dislocation density is highest with the smallest variation, forming a reinforced region within the material. The above results have significant implications for the design of environmentally friendly Bi-containing free-cutting steels.
Interface stabilization and propagation in phase field models of solidification: resolving the issue of large driving forces
Authors: Uddagiri Murali , Tegeler Marvin , Steinbach Ingo 
Published: July 2024

Abstract
One of the long-standing problems in the phase field, namely, combining the principles of thermodynamics and capillarity with the numerical aspects of interface propagation in simulations, is re-investigated. Numerical schemes are discussed which allow for stable simulations with arbitrary driving forces, considering or excluding capillarity. We re-investigate a classical stabilization scheme that decouples interface stabilization from curvature evaluation, ensuring stable simulations even under large driving forces. A novel mathematical analysis gives a rigorous estimate for the time stepping and a numerical value of the required stabilization strength. The proposed stabilization scheme is benchmarked for three-dimensional dendritic growth under directional solidification conditions for different solidification speeds.
‘Beyond Li-ion technology’—a status review
Authors: Banerjee Arghya Narayan , Joo Sang Woo 
Published: July 2024

AbstractLi-ion battery is currently considered to be the most proven technology for energy storage systems when it comes to the overall combination of energy, power, cyclability and cost. However, there are continuous expectations for cost reduction in large-scale applications, especially in electric vehicles and grids, alongside growing concerns over safety, availability of natural resources for lithium, and environmental remediation. Therefore, industry and academia have consequently shifted their focus towards ‘beyond Li-ion technologies’. In this respect, other non-Li-based alkali-ion/polyvalent-ion batteries, non-Li-based all solid-state batteries, fluoride-ion/ammonium-ion batteries, redox-flow batteries, sand batteries and hydrogen fuel cells etc. are becoming potential cost-effective alternatives. While there has been notable swift advancement across various materials, chemistries, architectures, and applications in this field, a comprehensive overview encompassing high-energy ‘beyond Li-ion’ technologies, along with considerations of commercial viability, is currently lacking. Therefore, in this review article, a rationalized approach is adopted to identify notable ‘post-Li’ candidates. Their pros and cons are comprehensively presented by discussing the fundamental principles in terms of material characteristics, relevant chemistries, and architectural developments that make a good high-energy ‘beyond Li’ storage system. Furthermore, a concise summary outlining the primary challenges of each system is provided, alongside the potential strategies being implemented to mitigate these issues. Additionally, the extent to which these strategies have positively influenced the performance of these ‘post-Li’ technologies is discussed.
Synergizing teacher collaboration to foster active learning strategies, student engagement and achievement in physics: a unified analysis across nine countries
Authors: Pongsophon Pongprapan 
Published: July 2024

Abstract
This investigation explores the nexus between professional teacher collaboration, active learning methodologies, teaching promoting student engagement in physics classes and physics achievement. Leveraging Trends in International Mathematics and Science Study Advanced 2015 data from 1729 physics instructors across nine countries, it probes the extent to which collaborative practices among teachers influence their teaching to enhance active learning and engagement. Analytical techniques include Spearman correlations, confirmatory factor analysis, and structural equation modeling. Results reveal a robust model, confirmed by a Comparative Fit Index of 0.989 and Tucker–Lewis Index of 0.988, suggesting a good fit with the empirical data, alongside a Root Mean Square Error of Approximation of 0.053. The analysis demonstrates that teacher collaboration (‘Collab’) significantly predicts active learning (‘Active’) with a notable effect (β = 0.344, p < 0.001), which in turn significantly enhances student engagement (‘Engage’) (β = 0.438, p < 0.001). Additionally, ‘Engage’ is also directly influenced by ‘Collab’ (β = 0.174, p < 0.001). Although the relationship between ‘Collab’ and physics achievement (‘Physics’) is weaker, it remains significant (β = 0.063, p = 0.019). These findings support the enhancement of teacher collaboration as a catalyst for active learning and student engagement, which could indirectly foster improvements in physics achievement globally.
Physics card games to support knowledge organization: design considerations and teachers’ attitudes
Authors: Levy Smadar , Perl-Nussbaum David , Yerushalmi Edit 
Published: July 2024

Abstract
Despite the positive effects of gamification on student motivation and learning outcomes, there are still widespread concerns that ‘playing games is merely fun’ and have no added value, thus making teachers hesitate about incorporating games into their teaching. This paper describes Phys-Cards games, designed as a summative hands-on activity that highlights physics concepts through a ‘contrast and compare’ task in a game context. The Phys-Cards games were presented in a national network of professional learning communities (PLCs) for high school physics teachers. The teachers first played the games and then reflected on their experiences after they implemented them in their classrooms. Surveys and an analysis of the teachers’ reflections indicated that they valued the Phys-Cards games and reported that the games contributed to students’ conceptual understanding and knowledge organization. However, teachers faced challenges such as team size and composition, how to best monitor different groups, and timing in the instructional sequence. In their discussions during the PLC meetings, the teachers identified the features of the games that best promotedmeaningful collaborative learning and suggested productive ways to incorporate the games into their teaching.
Male bias in science and ways to counter it: gender imbalance of images in a science textbook in Irish secondary education
Authors: Politis Yurgos 
Published: July 2024

Abstract
There has been a steady decline of student take-up of physics as a Leaving Certificate subject, from 19% in 1991 to 13.6% in 2021. This comes in the backdrop of a projected increase in the international demand for STEM workers, which makes STEM education the bedrock for securing Ireland’s economic future. The gender bias in science textbooks is well documented and enduring. The lack of female representation in science textbooks’ images is exacerbated by the scarcity of female figures that would be broadly accepted as role models. This paper examines the gender balance of a science textbook used widely in the Irish junior cycle. For this purpose, the Gender Bias 14 Tool was chosen as the data collection instrument, which was developed by Parkin and Mackenzie. A clear majority of the 38 chapters of the book contain more images/illustrations with male than female figures, more images/illustrations that improve the image of men and more images/illustrations of male role models. Potential interventions are outlined including working closely with publishers to include more women in the textbook’s images, especially important and influential female figures, and working with teachers to help them enhance teaching with supplementary material that include more female representation through images.
Robust optimization and assessment of dynamic trajectory and mixed-beam arc radiotherapy: a preliminary study
Authors: Bertholet Jenny , Guyer Gian , Mueller Silvan , Loebner Hannes A , Volken Werner , Aebersold Daniel M , Manser Peter , Fix Michael K 
Published: July 2024

Abstract

Objective. Dynamic trajectory radiotherapy (DTRT) and dynamic mixed-beam arc therapy (DYMBARC) exploit non-coplanarity and, for DYMBARC, simultaneously optimized photon and electron beams. Margin concepts to account for set-up uncertainties during delivery are ill-defined for electron fields. We develop robust optimization for DTRT&DYMBARC and compare dosimetric plan quality and robustness for both techniques and both optimization strategies for four cases. Approach. Cases for different treatment sites and clinical target volume (CTV) to planning target volume (PTV) margins,

m

, were investigated. Dynamic gantry-table-collimator photon paths were optimized to minimize PTV/organ-at-risk (OAR) overlap in beam’s-eye-view and minimize potential photon multileaf collimator (MLC) travel. For DYMBARC plans, non-isocentric partial electron arcs or static fields with shortened source-to-surface distance (80 cm) were added. Direct aperture optimization (DAO) was used to simultaneously optimize MLC-based intensity modulation for both photon and electron beams yielding deliverable PTV-based DTRT&DYMBARC plans. Robust-optimized plans used the same paths/arcs/fields. DAO with stochastic programming was used for set-up uncertainties with equal weights in all translational directions and magnitude

δ

such that

m
=

0.7
δ

. Robust analysis considered random errors in all directions with or without an additional systematic error in the worst 3D direction for the adjacent OARs. Main results. Electron contribution was 7%–41% of target dose depending on the case and optimization strategy for DYMBARC. All techniques achieved similar CTV coverage in the nominal (no error) scenario. OAR sparing was overall better in the DYMBARC plans than in the DTRT plans and DYMBARC plans were generally more robust to the considered uncertainties. OAR sparing was better in the PTV-based than in robust-optimized plans for OARs abutting or overlapping with the target volume, but more affected by uncertainties. Significance. Better plan robustness can be achieved with robust optimization than with margins. Combining electron arcs/fields with non-coplanar photon trajectories further improves robustness and OAR sparing.
Experimental investigations into 3D printed hybrid auxetic structures for load-bearing and energy absorption applications
Authors: Bankar Shailesh Ravindra , Das Soumyadip , Sharma Varun 
Published: July 2024

Abstract
Auxetic structures possess negative Poisson’s ratio due to their unique geometrical configuration. It also offers enhanced indentation resistance, superior energy absorption capacity, excellent impact resistance, higher compressive strength, and other exceptional mechanical properties. In this study, multiple hybrid auxetic structures of three novel geometries have been designed by considering different sets of geometric parameters to numerically investigate the mechanical behaviors of the structures. The energy absorption properties and Poisson’s ratio of the developed hybrid auxetic structures have been measured under quasi-static compressive and bending loads. The numerically optimized structures from each of the three different geometries have been fabricated of acrylonitrile butadiene styrene using fused deposition modeling. Additionally, the simulated results have been experimentally validated. The validation studies have shown close agreement of their performances with the simulated results. Finally, comparative analyses of energy absorption performances have also been performed to select the most suitable structure for impact-resistant applications. Moreover, it has been observed that structure-2 exhibits superior performance in terms of maximum load-bearing capacity of 3395 N. On the other hand, structure-3 has the maximum energy absorption capacity of 51902 N.mm which is 4.85% higher than structure-1 and structure-2. Similarly, three-point bending test results have revealed that structure-2 performs better in terms of energy absorption capacity (10864 N.mm). Besides this, the effects of loading direction on deformation patterns and mechanical responses of the structures have been observed due to the changes in deformation mechanism. The high-velocity (8 m.s−1) impact test results have also confirmed the suitability of structure-2 for crashworthiness applications. The comparative findings derived from this study contribute significantly in developing lightweight, energy-absorbent, and impact-resistant auxetic core-sandwiched structures for civil, defense, and automobile sectors.
Mid-spatial frequency error restraint based on variable optimal angle-step trajectory strategy for the removal attenuation effect of magnetorheological finishing
Authors: Cai Lisheng , Hai Kuo , Li Zisheng , Fan Wei , Su Xing , Li Liangwei , Yan Ming , Li Jinbo , Huang Wen 
Published: July 2024

Abstract
In the field of ultra-precision manufacturing, such as lithography lenses, achieving nanometer-level errors across the entire frequency range is crucial. Magnetorheological finishing (MRF) technology, a high-precision processing method with high efficiency and low subsurface damage, often introduces mid-spatial frequency (MSF) error due to the removal attenuation effect and regular polishing trajectory in the long continuous polishing process. It causes various imaging and light transmission defects that limit the performance of precision optical instruments. The attenuation of material removal capacity of MRF is characterized by the attenuation of the tool influence function, which is obtained by an equal time interval point removal experiment. The variable optimal angle-step trajectory strategy is proposed to mitigate the removal attenuation effect of MRF and suppress MSF error. To validate the effectiveness and practicability of the proposed method, a uniform polishing experiment is performed on fused silica components. The experimental results show that the 90° grating trajectory introduces significant MSF error on surface shape with PV = 0.008 λ, and the variable optimal angle-step trajectory strategy does not introduce MSF error, which confirms the variable optimal angle-step trajectory strategy effectively eliminates the removal attenuation effect of MRF and suppresses MSF error. The study presents a general approach for ultra-precision optical processing and improves the manufacturing accuracy of optical components.