Search Results (99)

To optimize the laser drilling process and reduce the processing time, this study investigates picosecond laser trepan drilling on the titanium alloy TC4, analyzing the effects of laser parameters on micro-hole diameter, taper, and roundness. Four independent variables were selected: laser power, defocusing distance, scanning speed, and the number of scans. An L₂₅ (5⁶) orthogonal array was employed for experimental design. The mean response and range analyses evaluated parameter impacts on micro-hole quality, revealing the influence mechanisms of these variables at different levels. The results indicate the following: (1) the scanning speed and laser power significantly affect entrance and exit micro-hole diameters; (2) the defocusing distance substantially influences micro-hole taper; (3) the laser power most critically impacts inlet roundness; (4) the defocusing distance, scanning speed, and laser power directly correlate with outlet roundness; (5) the number of scans exhibits weaker relationships with inlet/outlet diameters, taper, and roundness. A comprehensive balance method applied to orthogonal test results for process optimization yielded the following optimal parameters: 90% laser power (30 W total), −0.2 mm defocus, a 27 mm/s scanning speed, and 15 scans. Full article

Mid-altitude sounding rockets are essential for atmospheric research and suborbital experimentation, where aerodynamic optimization and structural integrity are crucial for achieving targeted apogees. This study uses OpenRocket v23.09 for preliminary flight performance prediction and SolidWorks 2024 to integrate aerodynamic and structural analyses through Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA). SolidWorks Flow Simulation and SolidWorks Simulation are used to assess how nose cone and fin geometries, as well as thermal deformation, influence flight performance. Among nine tested configurations, the ogive nose cone with trapezoidal fins achieved the highest simulated apogee of 2639 m, with drag coefficients of 0.480 (OpenRocket) and 0.401 (SolidWorks Flow Simulation). Thermal–structural analysis revealed a maximum nose tip displacement of 0.7249 mm for the rocket with the ogive nose cone, leading to an increasing drag coefficient of 0.404. However, thermal deformation of the ellipsoid nose cone led to a reduction in the drag coefficient from 0.419 to 0.399, even though it exhibited a slightly higher maximum displacement of 0.7443 mm. Mesh independence was confirmed with outlet velocity deviations below 1% across refinements. These results highlight the importance of integrated CFD–FEA approaches, geometric optimization, and material resilience for enhancing the aerodynamic performance of subsonic sounding rockets. Full article

Understanding how disasters are framed in news media is critical to unpacking the socio-political dynamics of crisis communication. However, empirical research on narrative variation across disaster types and geographies remains limited. This study addresses that gap by examining whether media outlets adopt distinct narrative structures based on disaster type and country. We curated a large-scale dataset of 20,756 disaster-related news articles, spanning from September 2023 to May 2025, aggregated from 471 distinct global news portals using automated web scraping, RSS feeds, and public APIs. The unstructured news titles were transformed into structured representations using GPT-3.5 Turbo and subjected to unsupervised topic modeling using Latent Dirichlet Allocation (LDA). Five dominant latent narrative topics were extracted, each characterized by semantically coherent keyword clusters (e.g., “wildfire”, “earthquake”, “flood”, “hurricane”). To empirically evaluate our hypotheses, we conducted chi-square tests of independence. Results demonstrated a statistically significant association between disaster type and narrative frame (${\chi }^2=25,280.78$, p < 0.001), as well as between country and narrative frame (${\chi }^2=23,564.62$, p < 0.001). Visualizations confirmed consistent topic–disaster and topic–country pairings, such as “earthquake” narratives dominating in Japan and Myanmar and “hurricane” narratives in the USA. The findings reveal that disaster narratives vary by event type and geopolitical context, supported by a mathematically robust, scalable, data-driven method for analyzing media framing of global crises. Full article

The digital age, driven by advancements in data processing and internet technologies, has seen virtual social networks, particularly Instagram, become integral to daily life, influencing both leisure and professional activities. Instagram, with over two billion users in 2023, emphasizes visual storytelling, making it a pivotal platform for media outlets to engage audiences through photos and videos. This study quantitatively analyses the Instagram engagement and content strategies of five prominent legacy news outlets from the United States and the United Kingdom—The New York Times, The Guardian, USA Today, The Independent, and The Washington Post. Through an examination of over 9000 posts from January to December 2023, this research evaluates posting frequency, user engagement (likes and comments), hashtag usage, profile mentions, and geographic coverage. Findings indicate significant differences in posting strategies and engagement levels, highlighting The Washington Post’s intensive posting and The Guardian’s selective engagement strategy. This study emphasizes tailored strategies, thematic consistency, and careful use of mentions and hashtags as crucial for maximizing audience interaction. Full article

The combustion chamber is a critical component of turbojet engines, and airflow distribution plays an essential role in ensuring flame stability and optimizing combustion efficiency. This study investigates a miniature annular combustion chamber by employing SolidWorks 2022 software to model an evaporative tube combustion chamber. A dedicated combustion test platform was constructed for the proposed miniature combustion chamber. By adjusting the air and fuel flow ratios entering the evaporative tube, the temperature at the flame tube outlet was measured, and the combustion efficiency was subsequently calculated. In addition, numerical analysis was conducted using ANSYS/CFX software to simulate the flow field in the combustion chamber. The following conclusions were drawn from an analysis of the variations in the flow field and temperature field during the simulation process: When the flow rates in the ignition and dilution zones of the miniature annular combustion chamber remained constant, modifying the air-fuel flow ratio within the evaporative tube significantly enhanced the combustion characteristics within the chamber. Specifically, the combustion efficiency is closely related to the ratio of the air mass flow rate to the fuel mass flow rate within the evaporation tube. The highest combustion efficiency was achieved when the ratio fell within the range of 4.20 to 4.96. Furthermore, the area-averaged velocity at the combustion chamber outlet was independent of the air-fuel flow ratio but exhibited a positive correlation with the fuel flow entering the combustion chamber. Full article

Nuclear steam supply systems (NSSSs) are critical to achieving safe, efficient, and flexible nuclear power generation. While deep reinforcement learning (DRL) has shown potential in optimizing NSSS control, existing single-agent approaches apply the same optimization strategies to all subsystems. This simplification ignores subsystem-specific control requirements and limits both optimization efficacy and adaptability. To resolve this gap, we propose a multi-agent reinforcement learning (MARL) framework that independently optimizes each subsystem while ensuring global coordination. Our approach extends the current NSSS optimization framework from a single-agent model to a multi-agent one and introduces a novel MARL method to foster effective exploration and stability during optimization. Experimental findings demonstrate that our method significantly outperforms DRL-based approaches in optimizing thermal power and outlet steam temperature control. This research pioneers the application of MARL to NSSS optimization, paving the way for advanced nuclear power control systems. Full article

The conversion of n-hexane into its isomers is highly relevant in the petroleum refining industry due to its contribution to improving gasoline quality by increasing the octane number. This study presents a comparative analysis of eight reaction schemes for the C₆ series isomerization process. It was demonstrated that incorporating rigorous chemical equilibrium information, based on experimental data, yields virtually identical results across all schemes, enabling a detailed analysis. Five schemes were taken from the literature, two were modified to ensure linear independence, and one was proposed in this study under the same criteria. It was confirmed that using linearly independent schemes reduces the number of reactions without affecting model accuracy, facilitating its numerical solution. Each scheme was evaluated using simulations under industrial conditions with a kinetic model that includes 16 reactions. The results show predictions with average errors of 1.44% in reactor outlet temperature and 3.25% in molar flow rates. The kinetic constants for each reaction of the C6 series were generalized, ensuring their invariability regardless of the scheme used, allowing for their application to different schemes and eliminating the need for individualized tuning of the isomerization reactors in the process under study. Full article

With the increasing frequency of extreme rainfall events, enhancing urban drainage systems’ regulation capacity is crucial for mitigating urban flooding. Existing studies primarily analyze infrastructure impacts on peak flow delay but often lack a systematic exploration of time-lag mechanisms. This study introduces the time-lag parameter, using the hysteresis curve of the water level–flow rate relationship to quantify drainage system dynamics. An SWMM-based drainage model was developed for the Rongdong area of Xiong’an New District to evaluate the independent roles of green, gray, and blue infrastructures in peak flow reduction and time-lag modulation. The results indicate that green infrastructure extends the horizontal width and reduces the vertical height of the hysteresis curve, prolonging time lag and making it effective for small-to-medium rainfall. Gray infrastructure enhances drainage efficiency by compressing the hysteresis curve horizontally and increasing its vertical height, facilitating rapid drainage but offering limited peak reduction. Blue infrastructure, by lowering outlet water levels, improves drainage capacity and reduces time lag, demonstrating adaptability across various rainfall scenarios. This study systematically quantifies the role of each infrastructure type in time-lag regulation and proposes a collaborative optimization strategy for urban drainage system design. Full article

Out-of-home meals are characterized by poor nutritional quality, and their intake has been linked to adverse health outcomes. Therefore, national and local government initiatives have been implemented in the UK to promote healthier out-of-home meals. However, there is limited evidence of their effectiveness. This study evaluated the fat content and fatty acid profile of takeaway meals from ‘standard’ and from Healthier Catering Commitment (HCC)-approved takeaway outlets. Meals from 14 ‘standard’ and 13 ‘HCC-awarded’ takeaways (74 meals and 26 side dishes) were analyzed for total fat and fatty acid composition. No statistically significant differences in total fat, saturated, and trans fatty acids per 100 g and per portion between HCC and standard meals were observed, except for donner kebabs. Over 70% of all meals contained more than the recommended 30% of daily fat intake from a single meal. Some meals could provide more than 50% of the recommended total fat and SFAs intake. Despite businesses participating in the healthier out-of-home meal initiative, there has not been a significant improvement in the nutritional quality of the meals they offer. Further research to develop effective approaches to support independent takeaway businesses in offering meals with improved nutritional quality is warranted. Full article

Urban flooding disasters are increasingly prevalent because of global climate change and urbanization. University campuses, as independent functional zones, exhibit complex rainfall–runoff dynamics. This study focuses on the China University of Geosciences, using data from two extremely heavy rainfall events and on-site waterlogging investigations in Wuhan in 2020 and 2021. A stormwater management model was employed to simulate campus catchment runoff and pipe network performance under rainstorm scenarios of various return periods, illustrating the spatial and temporal evolution of waterlogging on the campus. The simulation results indicate that the discharge at the main outlets aligned with rainfall patterns but exhibited a delayed response. During an overload period exceeding one hour, the ratios of overflow nodes and overloaded conduits reached 72.22% and 57.94%, respectively. Ponding was concentrated mainly in the southwest region of the campus, with the maximum ponding depth reaching 0.5 m. Future flood mitigation measures, such as enhancing permeable surfaces, upgrading pipeline infrastructure, and promoting rainwater reuse, could support the development of a “sponge campus” layout to alleviate flood pressure and enhance campus sustainability and resilience. Full article

In the winter, a certain LNG receiving terminal operates exclusively with the submerged combustion vaporizer (SCV). However, due to the high operational costs associated with the SCV, a new combined operation scheme utilizing both the SCV and the open rack vaporizer (ORV) has been proposed. First, models for the SCV and ORV gasification units were developed in Aspen HYSYS and validated using actual operational parameters. Next, the relationship between the seawater inlet–outlet temperature difference and the minimum seawater flow rate for the ORV was determined, and an optimized seawater pump operation strategy, considering LNG export volumes, was formulated. Additionally, the relationship between the SCV fuel gas flow rate and LNG export volume was analyzed, and a comparison was made between the operating costs of SCV running independently and the combined SCV-ORV operation under winter conditions. The results of the combined operation experiments indicated that at a seawater inlet–outlet temperature difference of 3 °C, the joint operation mode could save costs by 70–77%; at 2.5 °C difference, it saves 60–67%; at 2 °C difference, it saves 45–50%; at 1.5 °C difference, it saves 35–38%; and at 1 °C difference, it saves 20–23%. This approach achieves optimized economic performance for LNG terminal operations. Full article

The media portrayal of artificial intelligence (AI) directly impacts how audiences conceptualize this technology and, therefore, its use, development, and regulation. This study aims to measure a key aspect of this problem: the feeling of AI anxiety conveyed by news outlets that represent this technology as a sort of “alien” that is autonomous, opaque, and independent of humans. To do so, we build an AI anxiety index based on principal component analysis (PCA) and apply it to a corpus of headlines (n = 1682) about AI published before and after the launch of ChatGPT in ten newspapers: The New York Times, The Guardian, El País, Le Monde, Frankfurter Allgemeine Zeitung, San Francisco Chronicle, Manchester Evening News, La Voz de Galicia, Ouest France, and Münchner Merkur. The results show that ChatGPT not only boosted the number of AI headlines (× 5.16) but also reduced positive sentiments (−26.46%) and increased negatives (58.84%). The AI anxiety index also grew (10.59%), albeit driven by regional media (61.41%), while it fell in national media (−6.82%). Finally, the discussion of the variables that compose the index reveals the opportunities and challenges faced by national and regional media in avoiding the feeling of AI anxiety. Full article

The advanced quality control of the raw mix remains a priority for the cement industry, particularly in recent years, where large quantities of alternative fuels and raw materials are used in clinker production, aiming to reduce the CO₂ footprint. This study presents an adaptive control system with a variable sampling period for regulating raw mix quality in the raw mill (RM) output in a process with four independent inputs and four outputs: the lime saturation factor (LSF), silica modulus (SM), alumina modulus (AM), and SO₃. The three pillars of the system are (1) mill dynamics calculation using exclusively industrial data, (2) the design of the controllers to meet robustness criteria, and (3) performance enhancement through simulators. Our technique periodically adjusts the gains of the controllers based on the mill’s dynamic parameters, which are computed from raw mix laboratory analyses. The presented results correspond to more than 14,000 h of mill operation. The standard deviation of the LSF at the mill outlet ranged from 1.5 to 3, which is equivalent to 1 to 2 standard deviations of LSF reproducibility. The standard deviation of the other moduli was close to the corresponding reproducibility of each. The presented adaptive gain-scheduling controller for LSF can be applicable to a broad range of raw meal grinding systems. Full article

Freezing damage to tunnels in cold regions has long posed a threat to the safe operation of high-speed trains and other means of transportation. Finding a reasonable and effective solution to this problem, while also considering green, low-carbon, energy-saving, and environmental protection measures, has garnered widespread attention. Herein, the concept of a novel coupled energy tunnel is proposed, which combines the technologies of an air curtain and ground source heat pump (GSHP). The aim is to effectively address the issue of freezing damage in tunnels located in cold regions, while ensuring traffic safety. First, the multifunctional experimental apparatus for testing the anti-freezing and insulation performance of a coupled energy tunnel was independently designed and developed for laboratory experiments. Second, single-factor experiments and orthogonal experiments are conducted, and the influences of five key factors (i.e., the air outlet hole diameter, air outlet hole spacing, circulating water temperature of the GSHP, wind speed at the tunnel model entrance, and airflow jet angle) on the internal temperature field of the tunnel model are discussed. Third, combined with range analysis and variance analysis, the ranking of importance for each key factor and the optimal scheme of the coupled energy tunnel are obtained as follows: wind speed at the tunnel model entrance D > circulating water temperature of GSHP C > airflow jet angle E > air outlet hole spacing B > air outlet hole diameter A, and the optimal scheme is A₂B₁C₄D₁E₂, i.e., the air outlet hole diameter is 3 mm, the air outlet hole spacing is 10 mm, the circulating water temperature of GSHP is 50 °C, the wind speed at the tunnel model entrance is 1.5 m/s and the airflow jet angle is 45°. In conclusion, the research achievements presented in this paper can offer a new perspective for the structural design of tunnels in cold regions. Additionally, they contribute to the early achievement of a carbon dioxide emissions peak and carbon neutrality, and provide some valuable and scientific references for both innovators and practitioners. Full article

Conceived as institutions funded by the public purse and intended to exist devoid of political influence, the mandate of public service media (PSM) entities is to disseminate reliable news content and high-quality audiovisual productions to all demographic segments, inclusive of marginalized communities and audiences that are typically under-served. Over the previous ten years, the rise in prominence of global platforms in national media systems has precipitated many changes in the media sector, including unique challenges for PSM institutions guided by specific public service values. Using a holistic conceptual framework for assessing the implementation of these values, this article analyzes the impact of platformization on Europe’s PSM and discusses how the Union’s policy approaches affect related challenges to PSM. The analysis indicates that while the European Union (EU) has accorded a high priority to PSM within its media policy framework, the role that Brussels plays in protecting the independence and efficacy of PSM has been circumscribed, given that the onus of regulating PSM entities rests with national governments. This has engendered contrasting experiences wherein certain PSM outlets enjoy political independence and command significant public trust while others function as state-controlled propaganda vehicles, advancing the objectives and interests of governing bodies. The EU has addressed global platform power in recent attempts to safeguard its digital future, including the Digital Services Act (DSA), Digital Markets Act (DMA), and the European Media Freedom Act (EMFA). However, these acts do not adequately address PSM’s two central and often interconnected problems: funding challenges and political pressures. Full article