Under the overarching vision of Healthy China, the imperative to investigate the design of health-oriented streets has gained paramount importance, aligning with the humanistic and sustainable evolution of urban landscapes. Addressing the limitations of existing health street evaluation methodologies marked by intricate indices, misalignment with the current state of China’s streetscapes, and a dearth of quantitative scrutiny, exploratory factor analysis was employed to distill latent variables. Through a structured approach encompassing health questionnaire analysis, structural equation modeling, and the quantification of health determinants, the research localizes health parameters and constructs a robust, quantifiable evaluation framework for street health. The analysis uncovers that four latent variables demonstrating significant positive correlations with street health outcomes, listed in descending order of influence magnitude: street quality improvement, accessible transportation provision, vibrant block development, and healthy environment promotion. The structural equation model-based quantitative analysis of street health elements furnishes scientific and empirical underpinnings for the development of superior health-conscious urban blocks. This methodological advancement not only refines the precision of street design geared towards health but also elevates the living standards of residents, thereby contributing to the realization of Healthy China’s aspirations.

Formation RF (radio frequency) systems compatibility is an important comprehensive ability that affects the survival and combat effectiveness of aircraft formation. It needs to be effectively assessed and verified through flight tests, and simulation can further optimize test design and improve test efficiency. Thus, a flight test method for formation RF systems compatibility based on simulation prediction was proposed. Firstly, the development trend of RF compatibility and is its capability requirements were summarized and analyzed. Secondly, a simulation model of formation RF systems compatibility based on interference conflict was proposed, and a flight test method of formation RF systems compatibility based on the interference conflict distance from simulation analysis was established. Finally, simulation analysis and flight profile design were conducted for a typical formation RF compatibility test. This study has provided an effective method for the test profile design and flight verification of formation RF systems compatibility.

A method for diagnosing AC series arc faults based on the Inception module and BiLSTM (bidirectional long short-term memory) was proposed to address the challenge of identifying small current changes caused by arc faults in aviation cables. First, features of the raw current data were extracted by calculating the discrete sum of squares of the autocorrelation coefficient, Shannon entropy, and wavelet energy entropy. These features are then combined to form a new feature matrix, enhancing the original data's feature representation. Subsequently, the Inception-BiLSTM network learns from the feature matrix and ultimately completes the arc fault diagnosis. To validate the diagnostic performance of the model in practical environments, a series of experiments were conducted, including vibration tests, stress tests, and wet cable tests, based on an aviation cable arc fault simulation platform, with the experimental data being integrated as detection samples. The experimental results show that the proposed method achieves a high accuracy rate of 99.69% in identifying arc faults.

In order to address a series of safety management issues involved in low-altitude economic development, the technical routes and principles of low-altitude economy as well as the operational experience of implementation plans are summarized, and four universal construction plans for low-altitude security and protection are analyzed, namely the radar and integrated perception technology fusion plan, the broadcast automatic dependent surveillance technology plan, the remote identification technology plan, and the multi-source fusion plan based on TDOA radio technology. On this basis, an evaluation index system for unmanned aerial vehicle detection technology was constructed, and a multi-attribute evaluation method based on DEMATEL and TOPSIS was established. The results show that the multi-source fusion plan based on time difference of arrival (TDOA) is an effective and universal solution for building a low-altitude security system in cities. It is concluded that the construction of a low-altitude security system is a systematic project, which requires the joint efforts of governments, enterprises and the whole society. Integration is needed at the levels of technology, data and operation to meet the future development needs of the low-altitude economy.

To investigate the mechanism and influencing factors of soil heating with coupled in situ thermal technology, a two-dimensional experimental setup was used to simulate the heat treatment process, and the effects of coupled steam injection on thermal conductive heating as well as the effects of steam injection rate and heating mode on the application of the thermal conductive heating and steam injection technology were investigated. The results show that coupling steam injection on the basis of thermal conductive heating treatment can accelerate heat transfer, reduce heat loss, shorten the heating time by 35.67%, and reduce energy consumption by 24.53%. The main mechanism of steam injection enhanced heating is as follows. The additional heat injection increases the temperature difference, which in turn enhances convective heat transfer in the liquid phase driven by buoyancy. The upward migration of steam under buoyancy or pressure to enhance convective heat transfer in the gas phase. In thermal conductive heating and steam injection treatment, changing the steam injection rate or heating mode had a small effect on the treatment energy consumption, increasing the steam flow rate from 0.18 to 0.54 kg/h can shorten the heating time by 22.05%, but increase the water consumption by 132.43%. Compared with the thermal conductive heating and steam injection heated at the same time, thermal conductive heating heated for 30 min and then coupled with steam injection can reduce the water consumption by 28.57%, but will extend the heating time by 3.84%. In engineering applications, suitable restoration solutions should be selected based on duration, cost, etc.

To accurately and comprehensively explore the entire process of physical fatigue development in rescue team members during weighted walking, a multidimensional fatigue assessment method based on eye movement characteristics, electromyographic signals, and subjective evaluation is proposed. Eight volunteers were recruited for the weight-bearing walking fatigue induction experiment. The glasses eye tracking was used to extract the eye movement data about ST (saccade time), average SS (saccade speed) and maximum SA (saccade amplitude). The correlation between the characteristics of eye movement and the degree of fatigue estimated by subjective evaluation was -0.857±0.059, -0.938±0.092, not correlated, respectively. The correlation with iEMG to judge fatigue degree was -0.782±0.090, -0.942±0.030, -0.928±0.026, respectively. Multiple linear regression analysis was performed on subjective score, iEMG value and eye movement parameters. The regression model yielded a coefficient of determination R²=0.989, with the following standardized coefficients: iEMG signals=0.27, ST=-0.16, SS=-0.513, and SA=-0.124. This study makes new explorations and attempts in the monitoring and evaluation methods of fatigue during weighted walking.

Utilizing the PyroSim numerical simulation method, a comprehensive study was conducted to investigate the mechanism of the smoke pull-through phenomenon in a top-central exhaust system under conditions of counter-flowing jets, with a focus on the effects of various exhaust powers. Changes in smoke layer thickness, temperature distribution, and airflow velocity within tunnels were investigated under conditions of enhanced exhaust efficiency. Critical exhaust efficiency thresholds associated with smoke pull-through phenomena were identified across varying heat release rates of fire sources. Furthermore, the critical Froude number for smoke pull-through in centralized exhaust systems was established under counter-flowing jet conditions, along with the critical exhaust rate coefficient required to prevent such occurrences. The findings revealed that as the exhaust power increased, the exhaust port R3, located farthest from the fire source, was the first to experience smoke pull-through, followed by R2, while R1 remained unaffected. An increase in the heat release rate of the fire source led to a corresponding rise in the critical exhaust power threshold for smoke pull-through. A moderate increase in exhaust power could improve exhaust performance; however, exceeding a specific critical value would trigger smoke pull-through, thereby reducing exhaust efficiency. At heat release rates of 20 MW, 30 MW, and 50 MW, the critical exhaust powers were identified as 80 m³/s, 100 m³/s, and 150 m³/s, respectively, with optimal exhaust powers of 50 m³/s, 70 m³/s, and 110 m³/s. Furthermore, the critical Froude number for smoke pull-through was determined to be 35, and the critical exhaust rate coefficient was 0.8.These findings provide a theoretical basis for optimizing the design of exhaust systems, enhancing efficiency, and promoting energy conservation.

As an important firefighting equipment, fire cylinders need to undergo regular safety evaluations during their service period. In order to efficiently and accurately evaluate the safety status of fire steel cylinders, a safety evaluation model suitable for fire steel cylinders was established based on the analytic hierarchy process and fuzzy comprehensive evaluation method. The feasibility of the model was verified through case evaluation. Secondly, the BP neural network based on MPGA (multi population genetic algorithm) is used to optimize the safety evaluation model of fire steel cylinders. This method improves the process of updating weights and thresholds of the BP neural network through multi population genetic algorithm, improving the accuracy of BP neural network prediction results and the efficiency of fire steel cylinder safety evaluation. Finally, the construction of safety evaluation models for fire steel cylinders based on BP, GA-BP, and MPGA-BP was completed using Python. By comparing and analyzing the prediction results of three models, it was found that the MPGA-BP neural network has the smallest prediction error, proving that the proposed MPGA-BP safety evaluation model has high accuracy and can more efficiently and accurately evaluate the safety of fire steel cylinders.

Machine learning technology is a hot research topic at present. It is widely used in various prediction, recognition and classification tasks with its strong learning ability and high versatility. The application of machine learning in computational structural mechanics was discussed, with emphasis on its role in material property prediction, structural damage analysis, improvement of traditional methods, constitutive equation establishment and differential equation solving. Through literature review, the advantages of machine learning algorithms such as neural networks, support vector machines and random forests in improving computational efficiency and design process optimization were summarized. It is pointed out that the combination of machine learning and classical computing methods provides a new way to solve engineering problems. Future research will focus on algorithm optimization, model improvement and interdisciplinary technology integration.

Long-term stockpiling of coal fly ash releases a large amount of toxic and hazardous substances, posing a threat to the soil and water environment. In order to have a comprehensive understanding of the research progress in this field, a bibliometric method was conducted to systematically and deeply visualize and analyze the relevant literature in CNKI and Web of Science databases from the period of database construction to 2023. The results show that the annual total number of publications in this field is generally on the rise. Among them, Chinese scientists have conducted a substantial amount of research in this field, accounting for the highest publication volume, which makes up 18.87% of the total, providing important scientific foundation for subsequent studies. The betweenness centrality of publications from the United States (0.51) is significantly higher than that of other countries, and its research results have greater international influence. The research hotspots focus on contaminants like heavy metals in coal fly ash, investigating their leaching and release patterns under various conditions, and revealing the environmental impacts of contaminants migration from coal fly ash landfills. Based on high-frequency keyword analysis, the composition of contaminants in coal fly ash and the types of contaminants potentially released into the water environment were examined. A systematic review and analysis of contaminants release mechanisms, release regularity, key influencing factors, and the migration regularity of mechanisms in environmental media were conducted. Future research should further focus on the release of heavy metals such as Pb, Cr, and Hg, trace elements like As, Se, and Mo, and specific mechanisms such as F^-, Cl^-, and $\mathrm{SO^{2-}_{4}}$, $\mathrm{PO^{3-}_{4}}$ during the coal fly ash stockpiling. Studies should explore the release characteristics of these mechanisms under complex environmental conditions, investigate whether synergistic or inhibitory mechanisms exist between various factors, and establish quantitative relationships between mechanisms indicators in the solid phase of coal fly ash and their release into water environment. This will provide a theoretical basis for scientifically evaluating the environmental impacts of coal fly ash and effectively preventing potential threats to water environment.