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New experimental and theoretical energy levels, lifetimes, and oscillator strengths in singly ionised zirconium
No full textContext. Neutron-capture elements are believed to make up almost all elements heavier than iron in the periodic table. By studying the abundance of these elements throughout the Galaxy, it is possible to put constraints on how and where neutron-capture processes occur. Determining elemental abundances is made possible through the correct interpretation and modelling of astrophysical spectra. Key ingredients for this, in turn, are accurate and complete sets of atomic data.
Aims. We investigate the spectrum of singly ionised zirconium with the aim of reporting level energies and radiative lifetimes for previously experimentally unknown high-lying even 4d26s and 4d25d levels, as well as improved energies for odd 4d25p and 4d5s5p levels. We also aim to provide wavelengths, branching fractions, and oscillator strengths (log gf values) for lines from these upper even 4d26s and 4d25d levels.
Methods. The energies, wavelengths, and branching fractions were derived from hollow cathode spectra recorded with a Fourier transform spectrometer. The radiative lifetimes were measured using a two-step laser-induced fluorescence technique. Theoretical calculations using the pseudo-relativistic Hartree-Fock method, modified to account for core polarisation effects, were also performed and show good general agreement with the experimental results.
Results. We report for the first time level energies and radiative lifetimes for 19 high-lying even 4d26s and 4d25d levels and improved energies for odd 15 4d25p and 4d5s5p levels in Zr II. We also report wavelengths, branching fractions, and oscillator strengths for 79 lines from upper levels of 4d26s and 4d25d
Role of vanadium in welding of flat products in high strength low alloyed steels: microstructure and mechanical properties
No full textThe use of High Strength Low-Alloy (HSLA) steels in structural applications requires detailed analysis of their microstructure to optimize the strength and toughness of welded joints. During multi-pass welding, thermal cycling generates a complex heat-affected zone (HAZ) with subregions containing brittle phases that can compromise mechanical strength. This study evaluates the effect of vanadium and niobium additions on the HAZ microstructure in 15 mm thick S355 steel welds produced by robotic GMAW welding. The results reveal a heterogeneous microstructure with ferrite of several morphologies, bainite, and martensite/austenite (M/A) islands. The presence of vanadium reduces the solubility of carbon during phase transformations, favoring the formation of ultrafine precipitates (∼11 nm) and reducing the M/A phase in the high vanadium (0.1 wt%) variant. Nevertheless, the micro-alloyed variants improve mechanical strength (yield and ultimate strength) without loss of ductility or fatigue resistance, exhibiting a stress dissipation behavior that favors resistance to crack propagation
Unveiling gravity-induced quantumness by three-measurement uncertainty relations
No full textThe effect of gravity is a key factor in understanding the physical phenomenon. Quantizing gravity is challenging task due to weak interactions of gravity in quantum world. The quantum nature of gravity can be witnessed by entanglement in an interferometric platform [Phys. Rev. D 105, 086024 (2022)]. A natural question arises concerning whether the quantization of gravity can be observed via other means. In this work, we propose an effective approach to witnessing the gravity-induced quantumness by quantum uncertainty relations, including entropy-based and coherence-based uncertainty relations. The theoretical frameworks for wave-particle, entropic uncertainty and coherence are established, which can prove the quantum nature of gravity. The three-measurement entropic uncertainty and coherence exhibit the oscillatory features for the gravity-induced phases in the interferometric scheme. It is found that the evolutionary dynamics of coherence is inversely correlated with the measured uncertainty. It can be interpreted that the reduction of systemic quantum resource leads to the increase of entropic uncertainty, and vice versa. When the entropic uncertainty reaches zero, systemic coherence is the maximum value, providing a viable physical explanation for the gravity-induced quantumness. It shows that the entropic uncertainty and coherence can be regarded as the reliable indicators for capturing the gravity-induced quantumness. Compared to entanglement-based gravity quantization scheme, it shows that the capabilities are equivalent for detecting the gravity-induced quantumness using entropy uncertainty, coherence, and entanglement. The results could lay a solid theoretical foundation for the potential applications of quantum gravity in quantum information science
Enhancing the detection of low-energy M dwarf flares: Wavelet-based denoising of CHEOPS data
No full textSingle-field D-type inflation in the minimal supergravity in light of Planck-ACT-SPT data
No full textThe minimal supergravity framework is applied to a construction of new D-type single-field models of inflation in agreement with precision measurements of the cosmic microwave background radiation by Planck Collaboration, BICEP/Keck Collaboration, Atacama Cosmology Telescope and South Pole Telescope. The inflaton potential, the power spectrum of scalar perturbations, the cosmological observables and the reconstruction procedure can be very simple when using the e-folds as the running variable
Study on the deformation law and influence of large passenger aircraft in full-scale aircraft static test
No full textThe full-aircraft static test constitutes a simulation of various load states, conducted on the aircraft structure within a fixed coordinate system in a laboratory setting. It is imperative to take into account the ultimate deformation and displacement of the aircraft. This paper introduces the main configurations in the process of aircraft development and analyses the special characteristics of the test configurations. Combined with the typical loading conditions of the full-scale static test of a large passenger aircraft, the deformation characteristics of the aircraft are analyzed, and the deformation laws of each major section under different loading conditions are summarized. The effects of large deformation of the aircraft structure on load calculation, load application, attitude control and test execution are analyzed. The study proposes key factors affecting the accuracy of the test, including the determination of the optimal position and attitude for the test condition, the precise control of the aircraft attitude, and the precise calculation of the load after the large deformation of the structure. In addition, the study puts forward evaluation indexes for the accuracy of the test from the three dimensions of load balance, stability of attitude, and reasonableness of data. The results of the study are of great value for the characterization of large deformation aircraft and for the lateral comparison of the quality of test precision
Urban Lighting and Circadian Disruption: A Systematic Review and Policy Framework for Sustainable Nightscapes
No full textArtificial light at night (ALAN) has surged greatly in the past decade, mainly due to the global shift to energy-efficient LED lighting. This sudden surge has triggered major concerns among scientists and public health experts about the potential impacts of ALAN on human circadian rhythms and sleep and health, highlighting the need for more research and possibly even lighting guidelines. This article will systematically review the researches on the impact of urban lighting on human circadian rhythm in the past in this article, we will screening and searching relevant studies using the PRISMA process system, and then we found that the short wavelength blue light induced inhibition of melatonin, delayed sleep, increased the risk of metabolic disorders; Simulation shows that "dynamic warm light curfew" can reduce the day and night loads by 35-50%. Based on the above, this article proposes that the current lighting standards cannot protect day and night health, and a "policy framework for time zone tailors' spectrum and timing to local solar and social time zones" should embed circadian metrics into municipal codes. The findings of this article provide evidence-based paths toward sustainable, healthy nightscapes
Research on new systems engineering technologies for aviation equipment R&D overall design
No full textR&D overall of equipment determines the selection of technical solutions, the design of developing routes, and the generation of combat capabilities, which is a systematic engineering of overall and decision-making significance. This paper studies the theoretical foundation of modern systems engineering and its specific practices in the equipment R&D field, proposes the technology principles of systems engineering, so as to more accurately grasp the essence of systems engineering theories, and scientifically guide their application in the aviation engineering field to achieve efficiency improvement. The logical relationship between equipment R&D overall and systems engineering is studied, and it is proposed that overall design in the equipment R&D field is a systems engineering. Some new systems engineering technologies for aviation equipment R&D are studied, such as aviation equipment R&D planning, list-based requirement management, technology-cost balanced design, rapid combat capability generated, and R&D-test-training-application system technologies, which can provide reference and guidance for the top-level planning and process implementation of aviation equipment R&D
Agricultural Productivity and Food Security Under Climate Change: Empirical Insights from Developing Countries
No full textThe research investigates climate-agriculture relationships through Panel Autoregressive Distributed Lag modeling which analyzes 20 developing nations during 2000-2020. The National CO2 emissions function as a combined metric which tracks climate change impacts through temperature shifts and agricultural system limitations due to environmental conditions. The research design includes variance inflation diagnostics together with robustness tests to handle problems that occur because of multicollinearity between variables. The research data shows that emissions create long-term damage to agricultural production while showing strong connections between climate change metrics and food availability problems. The Pooled Mean Group estimation shows that countries maintain stable long-run relationships but their short-term adjustment patterns differ substantially. The emissions-food insecurity linkages in developing economies with high emissions become most evident because these nations face severe climate risks and experience unequal benefits from agricultural production. The duration of climate change effects differs between agricultural systems which produce different crops because of multiple factors which exist between climate and agricultural systems. The research results demonstrate that policy makers need to create unified strategies which will help them reach their climate change reduction targets while improving agricultural output and protecting food production systems
Competitiveness of green hydrogen: A systematic literature review through the TCCM prism
No full textThis study presents a systematic literature review on the competitiveness of green hydrogen, with a particular focus on emerging economies. Faced with the urgent need to decarbonize sectors that are difficult to electrify, green hydrogen appears as a strategic option, but its widespread adoption remains hampered by issues of cost, technological maturity, and governance. Using the TCCM (Theory, Context, Characteristics, Methodology) approach, this research analyzes a corpus of 45 indexed articles to identify the major determinants of competitiveness. The results show that competitiveness does not depend solely on lower technological costs, but on a systemic combination of factors including stable regulation, suitable infrastructure, innovation, partnerships, and financing mechanisms. The comparative analysis also reveals different trajectories among importing, exporting, and emerging economies, confirming that competitiveness is contextualized rather than universal. The synthesis ultimately highlights a “triangle of competitiveness” based on regulatory stability, secure financing and the development of shared infrastructure, an essential condition for the transition of green hydrogen from the status of a promise to that of a deployed industrial sector