Volume 14
Published on December 2024This rise in the deployment of lithium-ion batteries in electric cars presents new fire hazards, especially in places such as tunnels where thermal runaway situations are highly dangerous. This work investigates the propagation of thermal runaway in lithium-ion batteries within tunnels, including smoke flow, toxic gas diffusion and heat distribution under various ventilation conditions and tunnel shapes. Tests with 18650 lithium-ion cells were carried out on tunnels with gradients (0°, 2°, and 5°), followed by CFD simulations of the results. We measured smoke spread, temperature, and toxic gas concentrations (CO, HF, CO2) at airflow rates from 0.5 to 3 m/s. The findings indicated that tunnel slope and ventilation rates had a direct influence on smoke content, gas content and evacuation probability, and that sloping tunnels held more smoke at the ends. These results underscore the need for tailored ventilation to facilitate egress and avoid exposure to toxic gases. This work can inform better fire-safety practices in tunnels as electric vehicles continue to become more common.
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The use of 3D printing in micro-optics manufacturing presents new possibilities for precision, flexibility and customisation in manufacturing advanced optical devices. It describes the design and optimisation of 3D-printed MLAs and gratings for high-resolution sensing and display devices. Comparing stereolithography (SLA) and two-photon polymerization (2PP) as primary fabrication methods we find the strengths and weaknesses of each, with 2PP being sub-micron resolution and best suited for complex micro-optical design. A hybrid approach combining SLA for coarse structures and 2PP for finer structures allows for scale-up. The choice of materials, especially the use of high-refractive-index nanoparticle composites, can help to improve optical properties. By imaging and spectral measurement, we find that the optimized MLAs exhibit better focal resolution and uniform light scattering, while the 1 m-pitch gratings possess high diffraction efficiency throughout the visible range. These findings illustrate how 3D printing with advanced materials offers a cost-effective and feasible option to fabricate individualised micro-optical instruments for imaging and spectral research.
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With the introduction of artificial intelligence (AI) into education, China’s English education in the university has also been affected. The COVID-19 pandemic accelerated the application of AI tools in education. This study investigates the practical use of AI tools in English learning among Chinese undergraduates before, during, and after the pandemic. Students’ perspectives were collected through questionnaires. And its data was analyzed by using frequency analysis and multiple response analysis in SPSS. Teachers’ perspectives were gathered through interview. The study explored their views, attitudes and experience with AI-assisted learning tools such as online learning platforms, generative AI, machine translation tools and speech recognition software. The findings revealed that the integration of AI into English learning has produced positive outcomes in practical application. Students have actively embraced AI-assisted English learning, with AI tools meeting diverse learning needs, significantly improving learning efficiency, and personalizing learning resources. Some teachers also recommend students to use AI tools to assist their learning as needed. Although teachers and students generally holding a positive attitude towards AI-assisted English learning, they all express concerns about the ethical use and over-reliance on AI. Future research should focus on establishing ethical guidelines for AI use, strengthening regulation and innovating technologies for AI tools.
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In today’s era of rapid technological advancement, the precise measurement of metal strain holds crucial significance across numerous fields. From mechanical manufacturing to civil engineering, aerospace to biomedical sciences, understanding the strain behavior of metals under stress is essential for ensuring structural safety and the proper functioning of equipment. This paper focuses on five commonly used sensors for measuring metal strain: resistance sensors, fiber optic sensors, piezoelectric sensors, Hall effect sensors, and capacitive sensors. It delves into their working principles, practical applications, advantages and disadvantages, as well as future development trends, aiming to provide a comprehensive reference for research and practice in related fields.
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According to the renovation needs of construction projects and the actual situation of the site, it is necessary to closely combine the application of electronic information technology to provide solid technical support for the smooth implementation of the renovation plan, aiming to optimize and improve the performance of the building structure, and effectively prevent possible problems in the transformation process and subsequent applications. In addition, in the process of strengthening the effectiveness of construction engineering transformation and promoting the progress of the construction industry, it is necessary to deeply analyze the changes in the current situation, deeply think about the integration and application strategy of electronic information technology, and ensure that the transformation project can achieve the expected results and realize the full and efficient use of information resources. This measure can not only significantly reduce the potential risks in the transformation of construction projects, ensure the successful completion of the transformation tasks, but also help to adapt to the development of the times, maximize the advantages of electronic information technology, and inject new vitality into the transformation of construction projects.
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At present, lithium-ion batteries (LIBs) have been vastly applied and are widely being used for portable device, hybrid electric vehicles, and aviation field. Cathode materials, as the most important part in the LIBs, shows a profound prospect and potential. This study mainly focuses on the study of the means of how to improve the electrochemical properties and performance of the NCM cathode materials, examining the characterization of the NCM cathode materials through the characterization techniques. By referring different doping elements on NCM cathode materials, this paper aims to examine the structural properties, electrochemical performance, and stability of these materials under different dopants. Several characterization techniques, inductively coupled plasma (ICP), x-ray photoelectron spectroscope (XPS), Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscope (EDS), and x-ray diffraction (XRD) results have clearly displayed a large amount of figure on cathode materials, which help us to gain a better understanding on the characteristic of each cathode materials and help us to do the further calculation and study on cathode materials.
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As time goes by, shared bikes have become an essential element in people's life. However, due to the limited number and uneven distribution of shared bikes, it has brought some troubles to people's daily travel. In this paper, we establish an empty vehicle scheduling model with normal distribution and study the empty vehicle scheduling problem of shared bikes. This paper establishes a model based on real life, assumes different scheduling schemes, and compares different assumptions, so as to get better empty vehicle scheduling schemes. In this way, shared bikes will be more conducive to People's Daily travel and bring more convenience to people.
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BIM (Building Information Modeling) technology has been widely applied in structural design, serving as an essential tool for building informatization. By constructing 3D digital models, BIM achieves the integration of design, analysis, optimization, and management, significantly improving the efficiency and quality of structural design. The parametric modeling functionality of BIM simplifies adjustments and optimizations of structural schemes. Its visualization features enhance interdisciplinary collaboration and communication. Furthermore, the integration of emerging technologies such as cloud computing and big data with BIM opens new avenues for automation and intelligent structural design. In addition, BIM’s application in the renovation of existing buildings supports the extension of building lifespans and contributes to sustainable development. Given its significant advantages, this paper analyzes the characteristics of BIM technology and delves into its specific applications in structural design. The goal is to provide a reference for advancing BIM technology in structural design practices.
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Engineering project auditing is a core process to ensure the rational use of funds in engineering projects. With the development of information technology, the construction industry is undergoing a digital transformation. The application of BIM technology in engineering projects has significantly improved the efficiency and effectiveness of engineering project auditing. This paper delves into the application and innovation of BIM technology in engineering project auditing. First, it provides an overview of the basic concepts of BIM technology and its current application status in the engineering field. Next, the paper analyzes the problems and challenges faced by engineering project auditing and elaborates on the opportunities and advantages of applying BIM technology in this field. Finally, the paper proposes application scenarios for BIM technology in engineering project auditing, aiming to promote the development and innovation of BIM technology in the field of engineering project auditing.
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Swimming involves the interaction between the human body, water, and air. Reducing the resistance encountered in the swimming direction and increasing the propulsion force are two primary methods for improving swimming performance. This paper, from a mechanical (mainly fluid mechanics) perspective, introduces the development of our understanding of the propulsion mechanism in swimming and the underlying mechanical principles. It analyzes the mechanisms of resistance generation during swimming and its basic components, and explores methods of reducing resistance and increasing propulsion from the perspectives of technical movements and swimming equipment. The paper aims to provide basic mechanical insights to better understand the technical and tactical behaviors in swimming.
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