With the increasing demand for gaseous energy, the demand for equipment for storing and transporting gaseous substances is also growing. Cylinder-type vessels and tube trailer cylinders are the main equipment for storing and transporting gaseous substances, and both have highly similar structural types and damage patterns. Although these two types of equipment have different safety technical requirements, an external inspection mode is always adopted due to factors such as structural type, traditional inspection mode, and operability. However, using an external inspection mode for detecting high-risk internal surface defects does not yield satisfactory results, as it is prone to missing the detection of defects, with certain drawbacks. If an internal inspection is to be conducted, specific inspection equipment must be used, and a series of problems, such as the contracting and expanding of inspection device components, stable support, and multi-directional driving, must be solved.

To address the deficiencies existing in external inspection and develop an inspection mode that can replace the external inspection mode, we focus on the characteristics of “small mouth and large belly” of cylinder-type vessels and tube trailer cylinders and develop a dedicated internal inspection device based on the required functions of an internal inspection platform. This device is constructed using a modular combination of a detection sensor module, an internal support module unit, a cylinder mouth support module, a motor module, and a drive rod module. The drive rod comprises multiple short rods connected together, and its length can be continuously increased as the detection progresses. Considering its structural strength, stiffness, and lightweight, the device's main material is aluminum alloy. The analysis involves technologies such as mechanics, electronics, control, simulation, and testing by adopting a method that combines theoretical calculation, simulation modeling, and experimental analysis.

The internal inspection device is easy to install, and the support frame can be flexibly contracted and expanded to achieve “in and out” capabilities. It can also be equipped with various detection sensors. The device can adopt two detection operation modes: axial stepwise circumferential detection and circumferential stepwise axial detection. Although the device has a long rod structure, the maximum deflection generated by the drive rod is acceptable, and the positioning error caused by the drive rod's torsional deformation can be automatically compensated through the program. We installed multichannel eddy current detection sensors, conducted experiments using comparison specimens, and performed tests at the equipment site. After repeated experiments and tests, the device was proven to be practical, reliable, and stable, capable of performing automatic detection andmeeting the internal inspection and detection requirements of cylinder-type vessels and tube trailer cylinders.

In summary, the internal inspection device provides a new platform for inspecting large-volume cylinder-type vessels and long-drum trailer cylinders, solving the long-standing problem of the inability of internal inspection for these systems. The internal inspection mode not only complements external inspection but can also replace the traditional inspection mode, providing an effective means for inspecting new composite material cylinder-type vessels.

Typhoons, characterized by sudden onset, extensive geographic impact, and considerable destructive power, pose recurring threats to the stability and safety of power grid systems, particularly in China's coastal regions. As extreme weather events become more frequent due to climate change, conventional emergency management approaches are inadequate. These methods often suffer from fragmented knowledge sources, inefficient information extraction, and limited support for intelligent decision-making. Hence, this article proposes an integrated technical framework that combines knowledge graphs with large language models (LLMs). This study aimed to improve risk perception, enhance decision-making accuracy, and bolster emergency response effectiveness in typhoon-triggered power grid incidents. Zhejiang Province, a coastal area frequently impacted by typhoons, was selected as the demonstration case for the framework.

The framework of knowledge graph construction included the design of two graph types: one derived from accident reports and the other derived from emergency plans. The accident-based knowledge graph was structured according to the Triangular Framework for Public Security Science and Technology at the schema layer. It organized knowledge into three primary dimensions: emergency events, affected infrastructure, and corresponding emergency management strategies. Meanwhile, the emergency-plan-based knowledge graph was structured based on the electric power production life cycle, covering key stages such as power transmission, power transformation, power distribution, power utilization, and energy storage. Both graphs worked together to support emergency planning. The system employed a hybrid approach at the data processing layer that integrated BERT with a bidirectional long short-term memory network. This hybrid model performed named entity recognition and relationship extraction. The extracted entities and relationships were visualized to improve model interpretability, enabling domain experts to validate and understand the underlying information. An enhanced discriminative similarity algorithm was introduced in the knowledge fusion process. Initially, cosine similarity and Pearson correlation filtered out low-relevance entity pairs. High-similarity entities were then semantically validated using the LLM, ensuring accurate fusion and reducing erroneous entity alignments. Experimental results showed a 10.11% improvement in accuracy compared to conventional methods. The final knowledge graphs were stored in the Neo4j graph database, which supported interactive visualization and real-time query functionalities. The system enabled intelligent reasoning for handling real-world disaster scenarios in the application stage. Using the Cypher query language, this study conducted a fuzzy query based on disaster descriptions. Relevant information was retrieved from the knowledge graph as a structured knowledge base. The ECO-STAR prompting template was used to guide the model in generating targeted risk analyses and emergency recommendations.

A case study was conducted in Zhejiang Province to validate the proposed framework. The results showed that integrating knowledge graphs and LLMs improved semantic precision. The integration also enhanced the relevance of decision support outputs. In addition, it reduced hallucination phenomena that often occurred when general-purpose LLMs were applied in specialized domains.

This study highlights the value of leveraging LLMs in constructing an emergency knowledge graph for power grids during typhoons. The proposed method offers a scalable, intelligent solution for managing power grid emergencies during typhoons and serves as a valuable reference for enhancing the disaster resilience of energy systems.

Safety evacuation and passenger transportation are key components of metro crowd control, requiring critical research related to passenger safety. With the rapid development of urban rail transit, a growing number of domestic and international scholars have conducted research on these components. To systematically understand developments and research trends in metro station safety evacuation and passenger transportation within the broader field of public safety, it is necessary to review and summarize relevant studies.

First, relevant Chinese and English literature on metro station safety evacuation and passenger transportation was retrieved from the Web of Science database and the China National Knowledge Infrastructure database, and relevant information about the studies was recorded. Next, a bibliometric analysis was conducted, including publication volume statistics and keyword analysis. This study reviewed and summarized the characteristics of the research content and methodologies regarding both safety evacuation and passenger flow management. It summarized the advantages and disadvantages of existing research approaches and methods, providing future development directions. Bibliometric analysis showed that research on safety evacuation in China has developed rapidly, although studies on passenger transportation require further attention. To date, research on safety evacuation has focused primarily on metro station fires, whereas studies on passenger transportation have concentrated mainly on the organization and control of large passenger flows. In the field of safety evacuation, metro station safety evacuation is characterized by multi-level enclosed spaces, multi-stage evacuation routes, and large passenger flows. Field experiments are difficult to implement due to their limitations, and microscopic models such as the social force model and cellular automaton model have thus become the primary research tools. Future research still needs to integrate intelligent algorithms, such as big data and machine learning, to dynamically optimize evacuation routes. In the field of passenger transportation, metro station passenger flow is characterized by complex, multi-directional movements and batch arrivals, and research in this area mainly relies on numerical simulation methods. Existing research primarily aims to reduce passenger waiting times and train delay times and has achieved relative maturity in optimizing train schedules and improving transport capacity. Implementing passenger flow control measures has become the main approach to reducing passenger flow risks. However, in actual metro operations, there remains a deficiency in the networked multi-station collaborative response mechanism for passenger flow organization.

This study conducted a bibliometric analysis of the literature on safety evacuation and passenger transportation in metro stations. It reviewed the characteristics and study methodologies used in the literature, while discussing research progress and existing limitations. The study contributes to understanding the current state of research and development trends in metro station safety evacuation and passenger transportation. Furthermore, it argues that future studies in China should place greater emphasis on passenger transportation and incorporate advanced intelligent algorithms into research on both safety evacuation and passenger transportation.

This research aims to explore the innovative integration of Ideological and Political education with general education in higher education institutions, exemplified by Tsinghua University’s “Class in the Desert” course. The study addresses the evolving challenges and opportunities in Ideological and Political education in the new era, focusing on enhancing students’ understanding of China’s northwest border regions, guide students fostering a strong sense of community for Chinese nation, and cultivating scientific thinking, patriotism, and a spirit of perseverance. By integrating practice-based teaching with Ideological and Political education, the course seeks to provide students with a vivid and immersive learning experience that goes beyond traditional class settings.

The research is based on a 21-year-long investigation and field study conducted by the teaching team in the Taklamakan Desert, Gurbantünggüt Desert, and the Tianshan Mountains. The “Class in the Desert” course was launched in 2023, combining on-campus learning, site visits, and extracurricular research focused on advanced scientific achievements and major projects in China’s western desert regions. The course content covers red resources, major national projects, ancient city ruins, and rural revitalization. The study analyzes the teaching design, implementation path, and effectiveness of the course in strengthening Ideological and Political education through both qualitative and quantitative methods. Data were collected from student feedback, course evaluations, and media coverage, and analyzed to assess the impact of the course on students' knowledge, values, and capabilities.

The course has achieved several innovative outcomes. Firstly, it breaks the traditional reliance on class lectures in Ideological and Political courses by integrating practice-based general education with Ideological and Political education. The course uses the unique desert environment as a platform to enhance students’ identification with China’s development path through experiential learning. Students gain firsthand insights into the technological advancements and engineering achievements in the desert regions, such as the Tianshan Victory Tunnel and the ±1 100 kV UHV Changji Converter Station, thereby deepening their understanding of China’s progress and national strength. Secondly, the course has developed a comprehensive teaching model that combines knowledge transmission, value shaping, and capability cultivation. It includes pre-class thematic learning, in-class multi-theme integration, and post-class summarization and reflection. Pre-class activities involve thematic learning sessions on topics such as desertification control, West-East Gas Pipeline, and West-East Power Transmission. These sessions provide students with a solid theoretical foundation before their on-site visits. During the course, students visit various sites, including historical museums, engineering projects, and rural revitalization initiatives, integrating Ideological and Political education with practical experiences. Post-class activities include daily summaries, group discussions, and reflective writing, which help students consolidate their learning and develop critical thinking skills. Thirdly, the course has been recognized as an exemplary integrated Ideological and Political and general education course at Tsinghua University, offering a new model for integrating Ideological and Political education with practical teaching. The course’s innovative approach has been widely covered by media outlets such as Xinhua News Agency, China News Service, and the Tsinghua University News Network, highlighting its impact and potential for broader application.

The study concludes that integrating Ideological and Political education with practical general education courses can significantly enhance the effectiveness of Ideological and Political education. The “Class in the Desert” course demonstrates that combining field experiences with class teaching can deepen students’ understanding of national development, foster a sense of national identity, and cultivate a spirit of responsibility. The course also highlights the importance of leveraging unique geographical and cultural contexts to create engaging and impactful educational experiences. This approach not only strengthens Ideological and Political education but also provides a new direction for the development of general education courses in universities. Future research should focus on further refining the integration of Ideological and Political education with diverse practical contexts and exploring its broader application in different educational settings. Additionally, the study suggests that similar courses could be developed in other regions to address specific local contexts and challenges, thereby enriching the overall educational landscape in higher education institutions.

The Shenzhen–Zhongshan Link immersed tunnel has a total length of 6 845 m, featuring eight two-way lanes, with the widest section expanding to 12 two-way lanes. It is the world’s widest cross-section immersed tunnel and China’s first subsea interchange tunnel. Traditionally, smoke exhaust systems in immersed tunnels have relied on sidewall-concentrated exhaust technology. However, owing to the ultra-wide cross-section and multi-node characteristics of the Shenzhen–Zhongshan Link immersed tunnel, this conventional approach reduces smoke exhaust efficiency and fails to meet safety requirements for personnel evacuation in the event of a fire.

To enhance tunnel safety, a new smoke exhaust system incorporating a transverse smoke exhaust duct and sidewall exhaust ports was designed. First, in accordance with relevant specifications and the standards of the American Fire Protection Association (NFPA 502), key technical parameters such as fire design equivalency and smoke exhaust volume were determined. Then, through theoretical analysis and numerical simulation, components of the exhaust system—ncluding the jet fan, transverse exhaust duct, exhaust fan power, and axial exhaust fan room—were designed and finalized. Finally, a smoke control strategy was developed for different fire scenarios. Traditionally, the experimental verification of tunnel fires has relied on small-scale model experiments or static tests in shorter full-size tunnels. However, owing to size effects and experimental limitations, ventilation and smoke exhaust verification could not be performed under real-world conditions.

For the first time, a full-scale fire experiment was conducted at three locations in the Shenzhen–Zhongshan Link immersed tunnel to evaluate the smoke exhaust system. Static and comprehensive tests were performed under 14 working conditions. Through these on-site fire experiments, the variation patterns of the velocity and temperature fields under different conditions were analyzed. The results of the full-scale experimental study confirmed that the new smoke exhaust system in the Shenzhen–Zhongshan Link immersed tunnel meets the required smoke exhaust design standards.

With the rapid development of the modern economy and the continuous acceleration of urbanization, population concentration has become severe, making large cities the ultimate gathering places for people. In major cities where land resources are scarce, the influx of outsiders from all over the world has made the rise of high-rise buildings inevitable. However, as the number of high-rise buildings increases, so do the risks associated with them, particularly fire accidents, which are among the most dangerous. In recent years, several serious high-rise building fire incidents have occurred.

This article summarizes research progress on building fires, reviews full-scale fire experimental examples, and analyzes the movement and diffusion of smoke within rooms, adjacent spaces, and stairwells caused by high-rise building fires. A full-scale experimental design for high-rise building fires was conducted, and the specific design methods for the fire source device, experimental measurement system, test conditions, procedural steps, and result analysis were explored. The experiment was carried out in an actual high-rise building in a certain city, and it incorporated four practical scenarios: multiroom blockage, adjacent multiroom setups, open large rooms, and stairwells.

The layout of the experimental measurement system for full-scale high-rise building fire scenarios was presented in accordance with design specifications. Considering the influence of fire source location and heat release rate under natural ventilation conditions, the temperature distributions of smoke in the fire area, adjacent rooms, and stairwells were measured in both horizontal and vertical directions, and the settling, horizontal, and vertical diffusion patterns of fire smoke were analyzed. High-rise building fires typically involve complex ignition factors, abundant flammable and combustible materials, rapid fire spread through multiple pathways, and intricate building structures, all of which significantly increase the challenges of firefighting and safe evacuation. Therefore, addressing the numerous fire safety hazards in high-rise buildings in China is an urgent priority. Full-scale fire experiments enable scenario simulations of fire accident evolution, allowing for the study of smoke spread characteristics and settlement patterns in high-rise building fires. This research contributes to optimizing building fire safety design and provides scientific support for enhancing emergency response capabilities and fire rescue efforts.

In fires originating from the basement or ground floor of high-rise buildings, the path of toxic smoke often intersects with the escape routes of the building occupants. This especially poses a significant risk when the smoke spreads vertically at an accelerated pace, threatening escapees and emergency rescue personnel. This study uses comprehensive field experimental data to reflect the progression of a fire to its fullest extent. In addition, the patterns of smoke diffusion and sedimentation were studied by observing experimental phenomena.

A fire experiment was conducted on-site in the basement of a high-rise building. Four different fire scenarios were created at various locations: a room corner, the front room of the stairwell, and the stairwell leading from the basement to the ground floor. The horizontal and vertical smoke temperatures in the fire area, adjacent rooms, and stairwells were measured and dispersed in real time. In addition, fluctuations in the air velocity during the experiment were recorded.

The results showed that in the fire area, there was a significant accumulation of smoke in the room after the fire. The smoke temperature maintained a relatively stable vertical gradient. However, the stairwell and its front room, which are connected to multiple areas, allowed a large amount of smoke to diffuse in neighboring zones, which resulted in reduced smoke accumulation and stable smoke stratification. Under experimental fire powers of 0.125 and 0.250 MW, the vertical temperature distribution in the fire area above a height of 3.50 m fluctuated significantly. Conversely, the smoke temperature below a height of 3.50 m remained consistent. In the room adjacent to the fire site, smoke initially spread across multiple interconnected areas. Despite this, smoke accumulation and settlement effects could still form further in the adjacent room and the stairwell's front room. In the stairwell's front room, which has a lower spatial limitation, smoke stratification was evident. Here, the spread of low-temperature smoke and air to distant rooms was more serious, resulting in a noticeable increase in the flue gas temperature in the lower space. In the stairwell, the smoke spread rapidly vertically. In the 0.125 MW fire scenario, smoke could reach the fourth or fifth floor area within 300 s, reducing the smoke layer height at the stairwell corner to 2.00 m, which poses a significant threat to personnel evacuation.

Through this analysis of smoke settlement characteristics in the fire area, the law of smoke spread and settlement characteristics in adjacent rooms and stairwells during 0.125 and 0.250 MW field fire experiments in the underground space of high-rise buildings is better understood. This knowledge of fire occurrence conditions, spread patterns, and smoke flow characteristics provides robust data support for smoke control design in the underground spaces of high-rise buildings. This approach improves the efficiency and effectiveness of fire response measures. This study successfully achieves its goal of analyzing smoke diffusion ranges and smoke layer heights.

With the continuous development of social and economic levels and the increasing demand for a higher quality of life, the scale and quantity of transportation tunnel construction in China continue to expand. The risk and harm of tunnel fires are increasing. Previous research has focused on single or bifurcated tunnels, lacking experimental research on fires for long-distance tunnels with double-hole tunnels.

This study focuses on a typical fire scenario of a double-hole long-distance highway tunnel, conducting full-scale experiments to evaluate the diffusion characteristics and temperature distribution of smoke under natural ventilation conditions and obtains basic data on double-hole tunnel fires. From the full-scale results, a computational fluid dynamics model was built, and further numerical simulation analysis was conducted to discuss the ventilation linkage mode of double-hole tunnels under fire conditions.

Smoke diffusion under different fire conditions was characterized by analyzing key parameters such as airflow velocity, smoke temperature distribution, and smoke diffusion time. The smoke control effects under different mechanical ventilation modes were compared using computational fluid dynamics tools. The results showed that: (1) Under natural ventilation conditions, when a smaller fire source power (eight oil pans) was used, the highest temperature point upstream of the fire source appeared at a height of 3 m instead of at the ceiling, and the temperature in the area between 3 and 4 m was higher. As the power of the fire source increased to 12 oil pans, the increase in thermal buoyancy increased the temperature to the highest point, approaching 3 m. (2) Mechanical ventilation reduced the doping effect of natural wind, stabilizing the distribution of the smoke layer upstream of the fire source, and the temperature upstream of the fire source was vertically distributed with the height gradient. Because of the opposite direction between mechanical and natural ventilation, the reduction in fresh air doping weakened the cooling effect of ventilation, resulting in a higher temperature under mechanical ventilation than under natural ventilation and a maximum temperature increase of 5-10℃. (3) For the flame inclination angle, as the combustion intensified, the thermal buoyancy gradually increased, and a larger plume buoyancy led to a smaller flame inclination angle. For flame length, as the heat release rate increased, the buoyancy of the plume increased, resulting in increased flame volume and length. (4) Based on the numerical simulation, the smoke control effects of single tunnel ventilation and left and right line linkage ventilation modes were compared. Under the set fire source power and position, the mode of smoke exhaust at end A and air supply at end B of the left tunnel while using the right tunnel for natural ventilation achieved the greatest benefits.

Smoke diffusion, temperature distribution, and fire source morphology in tunnel fires are discussed, and the ventilation mode for smoke control in tunnel fires is presented. The optimal ventilation mode under the set operating conditions is obtained from numerical simulation. The experimental results can provide data support and a technical reference for the smoke control design of tunnel projects with similar structures.

The design of Chinese high-speed railway tunnels, characterized by their high arched ceiling and large sections, presents unique challenges in terms of heat and mass transfer behaviors. These architectural features significantly influence the dynamics of smoke movement, resulting in distinctive patterns of longitudinal flow and temperature distribution of smoke during a fire, which differ markedly from those observed in conventional highway tunnels.

To investigate the specifics of smoke flow dynamics, this study embarked on full-scale fire experiments conducted within the Baijiashan tunnel of the Yuxiang high-speed railway between Chongqing and Qianjiang. These experiments were instrumental in capturing critical data on flame height and longitudinal distribution of smoke temperature under various fire scenarios. Building on this empirical foundation, the study analyzed the combustion stages and calculated the longitudinal smoke velocity for each fire scenario examined.

Previous literature has highlighted that the heat release rates in full-scale experiments were calculated based on the equivalent diameter of fire sources, with values of 0.38, 1.01, and 2.52 MW, respectively. It was observed that as the heat release rate increased, there was a corresponding significant uptick in the longitudinal velocity of the smoke. Within the confines of a high-speed railway tunnel, the vertical temperature distribution of fire smoke exhibits a distinct top-hat pattern. This characteristic distribution remains consistent farther from the fire source. Furthermore, this study delineates the boundary between one-dimensional shooting flow (Region Ⅱ) and critical flow (Region Ⅲ) within the context of a Chinese high-speed railway tunnel, identified as x/H ≈3.85 based on experimental data. The study also probes into the suitability of existing models for predicting the longitudinal flow and temperature distribution of fire smoke in long, narrow spaces such as high-speed railway tunnels. It was found that owing to the extended length of one-dimensional shooting flow (Region Ⅱ), models that assume constant smoke thickness fall short in accuracy within this region.

This study revealed that despite the larger net height and cross-sectional area of high-speed railway tunnels compared to those of conventional railway tunnels, the heat release rate of the fire source critically influences the speed at which smoke spreads longitudinally. Moreover, the evolution of vertical temperature distribution is determined by the convective heat transfer coefficient beneath the ceiling and the ceiling jet thickness. As the smoke spreads, the smoke velocity evolution, along with the convective heat transfer coefficient and ceiling jet thickness, gradually stabilizes. This stabilization contributes to the stable top-hat temperature profile observed vertically. Leveraging Froude scaling, a new model for the longitudinal attenuation of smoke temperature rise in Region Ⅲ of a Chinese high-speed railway tunnel has been developed and validated for x/H ≥3.85. The insights gained from this work enrich the experimental research on the characteristics of longitudinal smoke flow in Chinese high-speed railway tunnels. Moreover, the field data obtained on the longitudinal flow and temperature distribution of fire smoke offers theoretical support for evaluating how the longitudinal spread of fire smoke affects personnel evacuation strategies in Chinese high-speed railway tunnels.