[Objective] Considering the advancement in underground space construction in China, the number of single-end tunnels during the construction process has increased annually. To study the smoke-spreading characteristics of fires occurring in single-end tunnels formed during subway construction, a full-scale experiment was performed in the construction section of a subway tunnel.[Methods] The diffusion and settlement laws of smoke in a single-end tunnel were studied through the analysis of the overall temperature distribution, wind speed distribution, smoke layer height, and other tunnel parameters with on-site observation combined.[Results] The results indicate that under natural ventilation, the diffusion velocity of smoke is slower toward the closed end than toward the through end; moreover, the velocity difference decreases with increasing distance between the ignition source and the closed end.[Conclusions] The decay rate of ceiling flue gas temperature is slower toward the through end than toward the closed end. The distribution of flue gas at the connected end conforms to the classical model with the exponential decay distritution, while the closed end has a clear accumulation effect, forming a dangerous section. The height of the flue gas layer at the closed end is as low as 1.5 m, which is the key aspect for consideration in flue gas control and fire emergencies.

[Objective] Seismic damage and destruction of the stations, tunnels, and other structures considerably impair the functionality of the urban rail transit system. Current research on the system performance of the rail transit network primarily focuses on the scenarios of intentional attack and stochastic damage, which is dramatically different from the earthquake disaster scenarios. This paper proposed a quantitative framework to evaluate the seismic performance and resilience of rail transit networks. [Methods] The seismic fragility model was used to calculate the failure probability of the primary structural elements, including stations, tunnels, and bridges of the rail transit system. The graphical model of the network was established using the Space L modeling method. This approach was used to depict the interdependency of system elements. The network performance was expressed by the network efficiency weighted by passenger flow between rail transit stations. The Monte Carlo simulation was used to assess the uncertainty of the earthquake damage state of structures and the post-earthquake recovery of the damaged elements. According to the network performance curves during the post-earthquake recovery process, the seismic resilience index and resilience loss of the rail transit network were quantitatively evaluated using the concept of resilience triangle. Considering the Beijing rail transit network, the effects of earthquake intensity, recovery strategy on network performance, and resilience indexes were investigated. [Results] The results of the present analysis were as follows. (1) The resilience characteristics of rail transit networks under earthquakes, intentional attacks, and stochastic damage were different. The resilience index under earthquake damage was 0.936 3, whereas the resilience index under stochastic damage was 0.934 0. The resilience index under intentional attack was 0.863 4. (2) In the damage scenario corresponding to different earthquake intensities, the system resilience index calculated by the recovery sequence sorted by the dynamic importance of damaged elements were larger than that sorted by the static importance of damaged elements. Moreover, the damage scenario involving several damaged elements typically results in a larger difference between the resilience index calculated by the two recovery strategies. (3) Pre-earthquake enhancement measures to reduce the failure probability of crucial elements could effectively enhance the disaster resistance capacity of the network; however, their influence on improving the post-earthquake recovery capacity remained unclear. [Conclusions] Based on the seismic fragility models of the primary structure of the rail transit network, the graphical model of the network, and the importance of ranking-based post-earthquake recovery of the damaged elements, this paper establishes a framework to quantitatively evaluate the seismic resilience of rail transit network by the passenger-weighted network efficiency. When evaluating network resilience and comparing antiseismic improvement measures, multiple indicators such as resilience index, resilience loss, and recovery duration should be comprehensively analyzed. This framework can provide a reference for the seismic performance evaluation of the urban rail transit network and help decision-makers in allocating maintenance resources to restore the operation function of the urban rail transit system in a timely and cost-effective manner during the recovery process.

[Objective] Rapid prediction of rainstorm waterlogging is crucial for disaster prevention and reduction. However, the traditional numerical models for simulating and predicting large-scale and complex subsurface conditions are complicated and time-consuming; moreover, the time-efficiency requirement of rainstorm waterlogging prediction is difficult to meet. To address these shortages of the numerical models, this study constructs a spatiotemporal prediction model of urban rainstorm waterlogging based on machine learning methods to rapidly predict waterlogging extent and water depth changes.[Methods] This study constructs a rapid prediction model of urban rainstorm waterlogging based on a hydrodynamics model and machine learning algorithms. First, a hydrodynamic model is constructed based on InfoWorks integrated catchment management (InfoWorks ICM) for rainstorm waterlogging in the study area with the parameter rate determination and model validation to realize the high-precision simulation of urban rainstorm waterlogging. On this basis, a rainfall scenario-driven hydraulics model is designed to further obtain rainstorm waterlogging simulation results. These results are used as the base dataset for machine learning. Second, the spatial characteristics data of rainstorm waterlogging are obtained from three aspects: rainfall situation, subsurface information, and the drainage capacity of the pipe network, which, together with the grid simulation results, comprise the dataset. The spatial prediction models are based on random forest, extreme gradient boosting (XGBoost), and K-nearest neighbor algorithms. Finally, the simulation results of waterlogging points are used to generate rainstorm waterlogging time series data. The rainfall, cumulative rainfall, and water depth of the first four moments (every 5 min) are used as the input for a long short-term memory (LSTM) neural network to predict the present water depth of the flooding point. The two models collaborate to achieve rapid spatial and temporal predictions of urban rainstorm waterlogging.[Results] For spatial predictions, the random forest model has the best fitting performance regarding evaluation indexes such as the mean square error, the mean absolute error, and the coefficient of determination (R²). When a rainstorm scenario with an 80-year event and a 2.5 h rainfall calendar prediction set is used, the prediction results concur with the risk map of urban waterlogging in Beijing. Compared with the simulation results of InfoWorks ICM, the prediction accuracy of the predicted inundation extent reaches 99.51%, and the average prediction error of waterlogging depth does not exceed 5.00% by the random forest model. For temporal predictions, the trend of the water depth change of the LSTM neural network model is more consistent with the simulation results of InfoWorks ICM, the R² of four typical inundation points are above 0.900, the average absolute error of water depth prediction at the peak moment is 1.9cm, and the average relative error is 4.0%.[Conclusions] When addressing sudden rainstorms, the rapid prediction model based on machine learning algorithms built in this study can generate accurate prediction results of flooding extent and water depth in seconds by simply updating the forecast rainfall data in the model input. The model computational speed is greatly improved compared to the hydrodynamics-based numerical model, which can help plan waterlogging mitigation and relief measures.

[Significance] Since the turn of the 21st century, artificial intelligence (AI) has advanced considerably in many domains, including government affairs. Furthermore, the emergence of deep learning has taken the development of many AI fields, including natural language processing (NLP), to a new level. Language models (LMs) are key research directions of NLP. Referred to as statistical models, LMs were initially used to calculate the probability of a sentence; however, in recent years, there have been substantial developments in large language models (LLMs). Notably, LLM products, such as the generative pretrained transformer (GPT) series, have driven the rapid revolution of large language research. Domestic enterprises have also researched LLMs, for example, Huawei’s Pangu and Baidu's enhanced language representation with informative entities (ERNIE) bot. These models have been widely used in language translation, abstract construction, named-entity recognition, text classification, and relationship extraction, among other applications, and in government affairs, finance, biomedicine, and other domains. [Progress] In this study, we observe that improving the efficiency of governance has become one of the core tasks of the government in the era of big data. With the continuous accumulation of government data, traditional statistical models relying on expert experience and local features gradually suffer limitations during application. However, LLMs, which offer the advantages of high flexibility, strong representation ability, and effective results, can rapidly enhance the intelligence level of government services. First, we review the research progress on early LMs, such as statistical LMs and neural network LMs. Subsequently, we focus on the research progress on LLMs, namely the Transformers series, GPT series, and bidirectional encoder representations from transformers (BERT) series. Finally, we introduce the application of LLMs in government affairs, including government text classification, relationship extraction, public opinion risk identification, named-entity recognition, and government question answering. Moreover, we propose that research on LLMs for government affairs must focus on multimodality, correctly benefit from the trend of “model as a service,” focus on high data security, and clarify government responsibility boundaries. Additionally, a technical path for studying LLMs for government affairs has been proposed. [Conclusions and Prospects] The application of LLMs in government affairs mainly focuses on small-scale models, lacking examples of application in large-scale models. Compared with smaller models, large models offer many advantages, including high efficiency, broader application scenarios, and more convenience. These advantages can be understood as follows. In terms of efficiency, large models are usually trained on a large amount of heterogeneous data, thus delivering better performance. In terms of application scenarios, large models gradually support multimodal data, resulting in more diverse application scenarios. In terms of convenience, we emphasize the “pretraining + fine-tuning” mode and the invocation method of interfaces, making LLMs more convenient for research and practical applications. This study also analyzes the issues suffered by LLMs, specifically from the technological and ethical perspectives, which have resulted in a panic to a certain extent. For example, ChatGPT has generated many controversies, including whether the generated files are novel, whether using ChatGPT will lead to plagiarism and ambiguity as to who are property rights owners for the generated files. Overall, it can be said that LLMs are in the stage of vigorous development. As the country promotes research on AI and its application in government affairs, LLMs will play an increasingly crucial role in the field.

[Objective] Formations of fixed-wing unmanned aerial vehicles (UAVs), which are commonly used in military, rescue, and other missions, often do not have the ability to hover and have a large turning radius. Thus, when operating in an unknown environment, it is easy for the formations to collide in the presence of obstacles, which will gravely affect flight safety if not guarded against. It is difficult to avoid unknown environmental obstacles using traditional modeling methods. However, artificial potential field methods can address deadlock problems such as target infeasibility and cluster congestion. [Methods] To achieve the cooperation of UAV formations without collision, a deep deterministic policy gradient (DDPG)-based centralized UAV formation control method is proposed in this study, which is designed by combining the centralized communication architecture, reinforcement learning, and artificial potential field method. First, a greedy-DDPG flight control method is studied for leader UAVs, which improves collision avoidance effectiveness. Considering maneuver constraints, reward functions, action spaces, and state spaces are improved. Additionally, to shorten the training duration, the exploration strategy of DDPG is improved using the greedy scheme. This improvement mainly uses the critic network to evaluate the value of random action groups and improves greedy selection to make actions more inclined, thus achieving rapid updates regarding the critic network and accelerating the update of the overall network. Based on this, incorporated with the artificial potential field method and leader-follower consensus, a collision-free control method is designed for followers, which can ensure collision-free following cooperation. [Results] The numerical simulation experimental results show that the improved DDPG algorithm has a 5.9% shorter training time than the original algorithm. In the same scenario, the method that we proposed perceives the same number of obstacles as the artificial potential field method. The artificial potential field method has significant fluctuations in heading angle, while the proposed method has relatively small fluctuations. The DDPG algorithm has a smoother heading angle due to a smaller number of perceived obstacles; however, the minimum distance from the obstacles is only 9.1 m. The method that we proposed here is above 17 m from the obstacles. Furthermore, Monte Carlo experimental data under different scenarios of the long aircraft show that the ability of obstacle avoidance generalization of the proposed method is improved. Moreover, experiments were applied to the proposed formation control method. Under the same scenario and control parameters, the UAV formation control method based on the proposed architecture has lower formation errors during flight, with a maximum error of no more than 10 m. However, the artificial potential field-based formation control method has a maximum formation error of over 25 m. When encountering narrow gaps, our proposed method can quickly pass through without congestion, while the artificial potential field-based formation control method appears to hover in front of obstacles, which is not conducive to flight safety. During the entire flight, this method has a greater distance from obstacles and higher safety. [Conclusions] Compared with the original DDPG algorithm, the improved DDPG algorithm has faster training speed and better training effect. The formation control method can realize the formation flight of unmanned aerial vehicles under unknown obstacles. Compared with the formation control method based on artificial potential field, the formation control method avoids the hovering in place before obstacles, which is of great significance to the formation flight safety of unmanned aerial vehicles.

[Objective] Spontaneous coal combustion is one of the major natural disasters in coal mining; thus, accurate prediction of the risk of spontaneous coal combustion is crucial to prevent and control coal fire disasters. However, the complexity of the physicochemical process of spontaneous coal combustion and its various influencing factors poses a challenge to the risk prediction of spontaneous coal combustion. Strengthening research on spontaneous coal combustion hazard prediction technology using deep learning is crucial for improving the intelligent control level of coal mine safety production.[Methods] In this study, CO volume fraction was chosen as the index for spontaneous coal combustion evaluation. A dataset was constructed, and the field observation data were visualized. Next, the dataset was tested for the distribution of eigenvariables, normalized for the distribution of eigenvariables, and normalized for the dataset using kernel density estimation, logarithmic transformation, and maximum-minimum normalization. Finally, three algorithms, namely recurrent neural network (RNN), long short-term memory (LSTM) network, and gated recurrent unit (GRU), were applied to the data mining of spontaneous coal combustion feature information, and a dynamic sequence prediction model of spontaneous coal combustion CO volume fraction was established. During the model construction process, the full connectivity layer and Dropout class were added to prevent overfitting, and the mean square error and three model performance test indicators were introduced to analyze and optimize the model parameters and test the model performance.[Results] The results were presented as follows:(1) The CO volume fraction sequence dataset was established based on the field data of the Dafosi Coal Mine, the model generalization capability was enhanced, and the training time of the model was shortened by preprocessing the dataset. (2) The RNN, LSTM, and GRU models achieved the dynamic prediction of CO with an error of less than 1 %. (3) The optimal parameters of the three models were determined from the mean absolute error (MAE), the root mean square error (RMSE), and R² of the training and validation sets. A comparative study using the model performance evaluation metrics revealed that the LSTM model had the highest prediction accuracy under the same sequence data, followed by the RNN and GRU models.[Conclusions] Using 285 sets of field data, the spontaneous coal combustion CO volume fraction sequence prediction models based on the RNN, LSTM, and GRU algorithms were established. The experimental values of the CO volume fraction were highly consistent with the predicted values, and the prediction error was less than 1 %. The model can predict the change in the CO volume fraction in future moments using the dataset. The results reveal that the dynamic time series prediction of CO volume fraction from spontaneous coal combustion using sequence models is possible compared with conventional static models. Moreover, the process of constructing the three models and optimizing the parameters can be employed as a basic study for developing sequence prediction models for other indicator gases.

[Objective] Leakage accidents in urban gas pipeline networks occur from time to time, and most of them are accompanied by secondary disasters, such as explosions, fires, and building collapses, which seriously threaten the safety of people's lives and property. Previous research on gas accident rescue capability primarily focuses on gas enterprises or indoor gas emergencies, and research on accidents associated with gas pipeline networks is lacking. Some studies have limitations, such as broad evaluation indicators, vague content, and limited scope of assessment objects, which cause difficulties in applying the evaluation system in practice. This study aims to identify the weaknesses in the emergency rescue process for accidents associated with urban gas pipeline networks, effectively assess the emergency rescue capabilities for such accidents, and help improve the emergency rescue efficiency and gas safety guarantee level. [Methods] Herein, the emergency rescue characteristics for accidents associated with urban gas pipeline networks were analyzed and summarized, and the rescue capabilities for these accidents were evaluated. First, based on an in-depth analysis of emergency plans and accident cases associated with gas pipeline networks, the emergency rescue elements of accidents were extracted and sorted. Furthermore, the emergency rescue process was constructed. By summarizing the limitations in emergency rescue, an indicator system comprehensively reflecting emergency rescue capabilities was established based on four aspects, namely humans, pipelines, materials, and management. The system included 4 first-level indicators, 12 second-level indicators, and 27 third-level indicators. Second, the subjective-objective combination weighting method of the analytic hierarchy process (AHP) and the criteria importance through intercriteria correlation (CRITIC) method were used to calculate the weight of each indicator to reduce the possibility of excessive subjectivity caused by expert scoring to a certain extent. Combining the weight of each indicator can help identify and focus on the indicators with a high degree of importance. Finally, an emergency rescue capability evaluation model was established using the fuzzy comprehensive evaluation approach to realize the quantitative evaluation of the emergency rescue capabilities for accidents associated with gas pipeline networks in specific regions. The model was applied to Zhangwan District, Shiyan City, Hubei Province. [Results] The results show that indicators such as the “supply-demand ratio of rescue personnel”, “effectiveness of information transmission”, and “formulation and revision of emergency plans” account for a relatively large weight compared to other indicators. The indicators of “cooperation and coordination ability of rescuers”, “equipment performance”, and “emergency drill effect” are the weak links in the emergency rescue process of accidents associated with the gas pipeline networks in the region. Therefore, the departmental interaction needs to be strengthened, the construction of the rescue coordination mechanism needs to be improved, and joint prevention and control and coordinated rescue capabilities need to be enhanced. Furthermore, to standardize emergency drill training, the safety production investment guarantee for local gas companies should be increased, and to improve the design and planning of training content, online and offline integrated learning is necessary. [Conclusions] The feasibility and applicability of the evaluation system were verified through the application case. This evaluation system for the emergency rescue capability of accidents associated with urban gas pipeline networks offers a theoretical basis and feasible approach for establishing, improving, and evaluating emergency measures for accidents associated with urban gas pipeline networks.

[Objective] The research on soil salinization is complicated, and the traditional literature review method struggles to grasp the development trend systematically due to its subjective nature. Hence, it becomes important and necessary to seek alternative methods to objectively summarize and analyze the existing research papers and reasonably guide the future development of this field. [Methods] Based on the quantitative analysis of the Web of Science and China's national knowledge network databases related to soil salinization and saline-alkali land management and its utilization in the past 30 years, this paper proposes a quantitative review method for obtaining the research trend in this subject. This paper uses various software tools, including VOSviewer, Citespace, and SPSS, to analyze the number of publications, cooperation networks, and keywords within this field. [Results] The results show a continuous increase in the research on soil salinization at home and abroad. The number of scholars participating in the study of soil salinization has also increased significantly. The primary stage of development was before 1999, the stage of stable development was from 2000 to 2011, and the stage of rapid development was from 2012 to the present. Despite significant progress, according to Kuhn's model, the field remains in the primary science stage, indicating ample room for development. English journals such as Agricultural Water Management and Science of the Total Environment and Chinese journals such as Soil Bulletin and Soil can be regarded as core journals in the field of soil salinization, with the highest number of publications and higher journal impact factors. China, the United States, India, Australia, and other countries (in order of the number of papers published by them) have made outstanding contributions to soil salinization research, with Chinese scholars leading in terms of the highest number of published papers and are the main force in the study of soil salinization. The cooperation network analysis shows the importance of research institutions and direct government agencies in promoting institutional cooperation. However, at present, most cooperations are limited to intra-institutional cooperation, but future efforts should focus on the positive impact of cross-context, cross-institutional, transnational, and interdisciplinary cooperations on leapfrog and diversified development of soil salinization research. Keyword burst detection shows that "biochar", "yield", "salt stress", "quality", "freeze-thaw cycle" and "water and salt transport" are the recent hot spots of concern. Additionally, keyword co-occurrence and trend analyses show the shift in research focus from irrigation and drainage and saline-alkali land improvement in the 1990s to soil-plant salt interaction mechanism, salt-tolerant plant cultivation, soil water and salt regulation mechanism, optimization control technology, research and development technology of saline-alkali soil amendment, large-scale applications, remote sensing monitoring of saline-alkali land, and salinization impact assessment. It represents the developmental trend of research on soil salinization and saline-alkali land management and its utilization from drainage improvement to comprehensive utilization. [Conclusions] The research results of this paper quantitatively highlight the research hotspot and developmental trend of soil salinization and provide a reference for relevant researchers to grasp the developmental trends of the field and explore valuable new research directions.

[Objective] Rail corrugation is a problem that needs to be addressed urgently and is one of the common technical issues limiting the development of contemporary rail transit. This study uses the finite element method to analyze the formation process of rail corrugation from the wheel-rail transient contact stick-slip vibration to provide new insights into the mechanism of rail corrugation and to understand the phenomenon of rail corrugation on the metro line. [Methods] This study examines the formation mechanism of rail corrugation using field measurements and numerical simulation. First, according to the on-site corrugation situation, a three-dimensional wheel-rail rolling contact model is developed using the finite element software ABAQUS, and its effectiveness is established. The contact stick-slip state is then analyzed during the wheel operation, and the influence of the rail surface and no rail surface defect on it is discussed. Furthermore, the relationship between stick-slip characteristics and corrugation formation is examined. Finally, the inherent characteristics of the wheel-track system and longitudinal wear characteristics of rail are analyzed using the complex modal theory and the Archard wear model to explain the formation mechanism of rail corrugation. [Results] The results revealed that when the wheel rolled over the smooth rail, the adhesion area was at the front edge of the contact area, and the middle and rear edges were the slip area, which was closer to the steady state dynamic calculation results, verifying that the established finite element model was effective. Moreover, the wheel-rail contact was always in a stable rolling state, indicating that the wheel-track system was not easily unstable, consequently making corrugation generation difficult. When the wheel rolled through the squat defect, the contact area was shown as two slip areas surrounding the squat; after the wheel rolled through the squat defect, the area of the wheel-rail contact patch decreased, and almost all of it showed slip. The squat defect changed the stick-slip state of wheel-rail rolling contact and promoted the slip of the wheel-rail interface, which induced the instability of the wheel-track system and caused the wear of the rail surface material; this might eventually form rail corrugation. The complex modal analysis showed that the rail surface defect exacerbated the inherent unstable vibration characteristics of the wheel-track system, and the unstable vibration frequencies fell within the measured corrugation passing frequency range. [Conclusions] The analysis results of wheel-rail contact stick-slip and complex modal reveal that the formation mechanism of rail corrugation can be attributed to the inherent unstable vibration of the wheel-track system caused by the excitation of the rail surface defect, and the unstable vibration is represented by the vertical bending vibration of the rail relative to the track slab. Thus, when the wheel passes through the squat defect, it will stimulate the transient fluctuation wear, which results in wavy wear on the rail surface. The characteristic wavelength of the longitudinal wear on the rail surface is 40～50 mm, which is consistent with the corrugation wavelength on the actual line; thus, the formation mechanism of rail corrugation is further validated in the process of quantifying rail corrugation formation.

[Objective] Saline-alkali soil is an important reserve resource of cultivated land and potential granary in China, and its management and utilization are related to national food security. Therefore, innovative techniques and amendments should be developed to address these challenges in saline-alkali regions. Among these, calcium supplementation is recognized as one of the most effective methods for ameliorating saline-alkali soil. In the past two decades, gypsum from the desulfurization of flue gas (FGDG) in coal-fired power plants has become a preferred calcium source for ameliorating saline-alkali soil because of its high calcium content and economic feasibility. Given that FGDG has developed into a soil amendment and has been widely used, a profound understanding of the progress of its patents can provide technical guidance for the large-scale amelioration of saline-alkali soil. [Methods] Based on the incoPat global patent database, a bibliometric analysis was conducted on 520 invention patents in the field of using FGDG to ameliorate saline-alkali soil from 2003 to 2022. The application and authorization trends, high-yield mechanisms, operational status, substance composition, and their correlation with patents in this field were systematically analyzed. In addition, a comparative analysis was conducted on the effectiveness of 52 patents with application cases. [Results] The results showed that the annual number of patent applications for using FGDG amendments to ameliorate saline-alkali soil has a trend of first increasing and then decreasing, with a peak period of 115 patents in 2016. Most patents take 20-30 months from publication to authorization. However, the overall proportion of authorization has shown a decreasing trend. The number of patents granted by universities and research institutes is higher than that granted by enterprises, whereas the number of patents jointly granted by universities and enterprises accounts for 15.6% of the total. A total of 37 patents were converted, 7 of which were pledged, accounting for 33.3% of the total number of grants, all of which were transferred by universities to enterprises and pledged by enterprises for financing. More than 70% of patents comprised three or more substances, primarily including organic and inorganic minerals, microbial agents, and nutrient supplements. Organic materials can directly provide nutrients for the soil to make up for the shortage of FGDG in terms of nutrients, with the frequency of application as high as 95.7%, followed by inorganic minerals, which account for 44.5%; microbial agents, which account for 41.3%; and nutrient supplements, which account for 21.3%. Compared with soils with or without other types of amendments, the application of FGDG amendments significantly decreased soil pH, exchangeable sodium percentage, and salt ions that are toxic to crop growth and increased soil Ca²⁺, SO₄^2-, and total/available nitrogen and phosphorus contents, which provided a better soil environment, thereby increasing crop yield. [Conclusions] Generally, research and development on FGDG amendments for saline-alkali soil amelioration have matured, and some innovative achievements have been transformed into real productivity; thus, the value of related patents has been increasingly highlighted. However, problems such as the relatively simple composition of current patents, unclear technical requirements for the amount of application and method, and serious homogeneity of patents have been encountered. In the future, we should strengthen the cooperation among schools, enterprises, universities, and research institutes, intensify research on the FGDG formula used in saline-alkali soil, and enhance the application benefits of FGDG amendments.

[Objective] The ridership characteristics of urban rail transit stations are closely related to the surrounding built environment and socio-economic factors, and the influence of different influencing factors on ridership characteristics also has temporal and spatial heterogeneity. Considering the complexity of influencing factors on station ridership, this paper uses the multiscale geographical weighted regression (MGWR) model to analyze the influencing factors of ridership at rail transit stations in different temporal scales.[Methods] This paper selects the station ridership on weekdays as the dependent variable, which is divided into five categories, including the average daily ridership, inbound ridership of morning peak hours, outbound ridership of morning peak hours, inbound ridership of evening peak hours, and outbound ridership of evening peak hours. A total of 23 independent variables are selected from three aspects: station attributes, connectivity, and the built environment. The variance inflation factor and Moran index are utilized to test the linear correlation and spatial autocorrelation between independent variables, respectively. The MGWR model is applied to construct the analysis model of ridership characteristics, and three indicators, including the residual sum of squares (RSS), adjusted R², and the corrected Akaike information criterion (AICc), are employed to compare the performance of the ordinary least squares (OLS), geographically weighted regression (GWR), and MGWR models. The influencing factors and their interaction with rail transit station ridership in different temporal scales are developed. Finally, this method is applied to analyze the influence degree of ridership characteristics at Nanjing rail transit station.[Results] The following results are presented. 1) The MGWR model is more reliable than the OLS and GWR models. 2) The average daily ridership analysis model, which ignores the impact of morning and evening peak hour ridership, has the most significant independent variables. 3) The distance to the city center has a significant negative impact on station ridership, indicating that the agglomeration of station ridership is evident when the station is close to the city center. 4) The stations with a high proportion of residential and living facilities have a strong attraction to the morning peak inbound and evening peak outbound ridership, whereas those with a low proportion of residential and livings facilities have a strong attraction to the morning peak outbound and evening peak inbound ridership. Three significant local variables, namely tourism facility POI density, enterprise and office POI density, and the ratio of floor area on commercial lands to the total floor area, are available, and these local variables have different impacts on rail transit ridership at different temporal scales. Tourism facility POI density has negative spatially varying impacts on the average daily ridership, inbound ridership of morning peak hours, and outbound ridership of evening peak hours. Enterprise and office POI density has a negative spatially varying impact on inbound ridership of morning peak hours but has a positive spatially varying impact on outbound ridership of morning peak hours. The ratio of floor area on commercial lands to the total floor area has positive and negative spatially varying impacts on inbound ridership during evening peak hours. This finding implies that not all the commercial buildings around the rail transit stations are attractive to the inbound ridership during evening peak hours.[Conclusions] The MGWR model considering spatial autocorrelation can capture numerous influence scales of different variables and reduce the deviation of results. The developed method in this paper achieves the expected goal and depicts the interdependence between ridership and influencing factors from the station level.

[Significance] China uses a large amount of hydropower, and the safety of hydropower dams is related to the safety of people's lives, properties, and the national economy. Therefore, regular inspection of dam defects in large hydropower plants is vital to ensure their safe operation. Most of the common dam defects, such as cracks and leakage, originate from the surface of the structure and can affect the service life of the dams. In recent years, remotely operated vehicles (ROVs) have been used for the underwater inspection of dam defects in hydropower plants, as they can mitigate many disadvantages associated with manual inspections while improving detection accuracy and efficiency. [Progress] Thus, we explore the environmental conditions of dams and the main content of dam defect inspection in hydropower plants and review the research on ROV application for underwater inspection in large hydropower dams. We find that different sensors can be combined with ROVs to inspect large hydropower dams underwater according to detection and operation needs. The method can achieve intelligent mobile inspection and remote control of dam operation safety, automatically identify dam defect characteristics, and store shore-station interactive information. At present, ROVs are less used for inspecting dam defects in large hydropower plants but are widely used in fields such as deep-sea exploration, undersea operations, and rescue assistance. The use of ROVs for crack and leakage inspection in hydropower plants has tremendous advantages. The research on using ROVs for the intelligent inspection of other structures has certain implications for developing ROVs for the intelligent underwater inspection of large hydropower dams. We analyze the progress of ROV technology in domestic and international research on hydropower engineering in terms of the overall technology, underwater absorber, power system, inspection technology, underwater positioning, and control system. Moreover, we explore the modular design and overall scale optimization of ROVs for underwater inspection in large hydropower dams, with the design objectives of lightweight, high stability, and high anti-current and anti-disturbance capability. Thrusters with high propulsion ratios have been developed to ensure high ROV power. Adsorbers have been added to the ROV systems to control the hovering of ROVs, which can also improve their underwater anti-disturbance ability to ensure stable detection and operation. Acoustic-optical inspection technology has been proposed to improve detection accuracy, and intelligent algorithms have been used for defect identification and image post-processing. Regarding underwater positioning and control systems, a complementary approach combining information from multiple sensors has been adopted, and the dam defect inspection is validated to improve the operational capability of the ROV movement and inspection. [Conclusions and Prospects] The use of ROVs for underwater inspection in large hydropower dams has major advantages in targeting cracks and other dam defects, and the research on the intelligent inspection of hydropower dams opens up a wide range of prospects.

[Objective] Emergency relief supplies are crucial for dealing with disasters, and their reasonable and timely distribution relates to people's health and safety. Emergency relief supplies at rescue centers are limited and cannot meet the emergency needs of all affected areas simultaneously. Post-disaster emergency relief supplies face double challenges in this regard due to short supplies and limited transportation capability, resulting in the needs for medical rescue and materials of a disaster area in a short period. To develop a scientific and efficient post-disaster emergency response, we studied the constrained vehicle routing of emergency relief supplies based on demand urgency. Restrictions in traditional path planning, such as single objective, single depot, single distribution, undifferentiated supply, and closed scheduling, were considered.[Methods] The analytic hierarchical process was applied to measure the demand urgency index from personnel, facilities, and disaster resistance, considering the overall efficiency and key disposal. Furthermore, this study had multiple objectives, including the following: minimization of deprivation cost and response time, and maximization of demand satisfaction rate in the emergency rescue process. A constrained model of emergency vehicle routing was constructed, and a two-stage genetic algorithm was designed to deal with comprehensive distribution conditions, such as open scheduling, soft time windows, and demand splitting. The effectiveness and feasibility of the model and algorithm were verified using examples.[Results] The results revealed that the model effectively coped with the material distribution problem resulting from scarce transportation capacity and various degrees of disaster. The splitting strategy and open scheduling of vehicles guaranteed multiple services at disaster sites and optimal route combination. Moreover, relief progress in disaster sites (splitting demand, batch distribution, and service time) and vehicle dispatch schedules (distribution order, work duration, and resupply depot) were generated. During the planning period, the system loss was reduced by 40.3 %, and a 99.4 % material demand was obtained. When disaster derivation caused changes in road conditions, fluctuation parameters were inputted into the model. The model and algorithm adjusted the scheme with a low risk of service failure, and the adjusted scheme reduced the demand and supply by 1.5 % in the decision period.[Conclusions] Constrained route planning is implemented for flexible distribution conditions, such as demand splitting, soft time windows, and open scheduling, based on the dynamic change characteristics of demand and supply during sudden natural disasters. This study considers the demand urgency of key disaster areas and the efficiency of global relief to accommodate unexpected road events and maximize resource availability. With the circulation of distribution vehicles, the needs of disaster sites are gradually met within the decision-making cycle, which provides full play to the time utility of emergency relief supplies and transportation resources. The proposed model can form scientific and reasonable material distribution and vehicle scheduling schemes and evaluate the workload of each rescue center and vehicle to deploy work in advance, providing a theoretical basis and a decision-making reference for vehicle route planning of emergency relief supplies.

Image analysis is an efficient and accurate method for identifying hydropower dam surface defects. However, due to the complex background of dam crack images and the uneven proportion of cracks and background pixels, the detection effect of traditional algorithms is poor. Moreover, traditional artificial crack inspection is not only inefficient but also costly in the present day. Efficient and accurate dam surface crack detection techniques are crucial for dam maintenance and operation. In order to achieve accurate and efficient dam surface crack detection, a dam surface crack detection method based on an improved DeepLabV3+ model is proposed. Model training is carried out for the self-made dam surface crack image dataset of a hydropower station in Southwest China, and the model is evaluated by F_1,score, Z_MIoU, Z_MPA, parameter quantity and other indicators. The following improvements are made to the traditional DeepLabV3+ network model: (1) A three line attention module is added to improve the model's ability to extract crack pixels and reduce proportion imbalance between background pixels and crack pixels. (2) The original pyramid pooling module is cascaded for model optimization so that the model can achieve more intensive pixel sampling, and subsequently obtain more abundant crack features. (3) In order to solve the problem of the significant/too large number of traditional DeepLabV3+ network parameters, MobileNetV2 network is used as the backbone of the model to extract the network, to reduce the network to a lightweight module, and to reduce model parameters. (4) Focal loss and Dice loss are used as the loss functions of the model to overcome the data imbalance and to improve the accuracy of network classification. The improved DeepLabV3+ network model in this paper could better realize the extraction of crack pixels, reduce the problems caused by the imbalance of pixel proportion, and better ensure the efficient and accurate detection of dam surface cracks. The experiment on the self-made dam surface crack image dataset of a hydropower station in Southwest China showed the following: (1) Compared with the original model, the improved DeepLabV3+ model increased F_{1, score} by 3.33%, Z_MIOU by 2.89%, Z_MPA by 1.12%, and the parameters were reduced to 3 014 714. This finding showed that the improved model proposed in this paper had stronger performance than the original model, better ability to extract crack pixels, and could better complete the task of crack identification. (2) Compared with other attention mechanisms, the three line attention module proposed in this paper had certain advantages, which could increase the attention of the model to the crack pixels and enable the model to extract the crack features needed. Through an analysis of the experimental results, the model improved in this paper has stronger segmentation ability, less missing data and false detection, and can effectively complete the dam surface crack segmentation task. The improved method increases the efficiency and accuracy of dam surface crack detection and reduces the model parameters. It can provide powerful data support for crack detection and the safe operation of hydropower projects.

[Objective] In recent years, a large number of nonconvex, highly nonlinear, multimodal, and multivariable complex optimization problems have emerged in scientific and engineering technology design due to the continuous development of science and technology. Owing to their advantages such as simple programming, flexible operation, and efficient optimization, intelligent optimization algorithms have become research hotspots to address diverse complex optimization problems in engineering applications. They have been successfully used to solve practical problems such as neural networks, resource allocation, and target tracking. In this research, multiple strategies were developed to improve the existing monarch optimization algorithm to address its shortcomings, such as slow convergence speed, low optimization accuracy, and ease of falling into local extremum. [Methods] First, the forward normal cloud generator is used to perform nonlinear cloud operation on the parent monarch butterfly, increasing the number of candidate solutions and improving the local development ability of the algorithm. Subsequently, an opposition-based learning strategy based on convex lens imaging is used to the current optimal individual which is generated by normal cloud generator to generate new individuals and improve the convergence accuracy and speed of the algorithm. Finally, adaptive strategies are incorporated into the adjustment operator to diversify the population. [Results] Several experiments were performed on benchmark functions to verify the performance of the algorithm: (1) Different strategies proposed were analyzed using ablation experiments to verify their effectiveness. The results revealed that the proposed strategies can effectively improve the algorithm's performance. (2) The improved algorithm was compared with other swarm intelligent optimization algorithms, and the results revealed that the improved algorithm can achieve the best results on most test functions. (3) The improved algorithm was also compared with other improved versions of monarch optimization algorithm, and the results revealed that the improved algorithm exhibited more advantages such as fast convergence speed and high convergence precision. (4) The Wilcoxon rank sum test and Friedman test were used to verify the performance of the proposed algorithm. The results revealed that the improved algorithm is superior to other algorithms. [Conclusions] The optimization and comparison results of the pressure vessel design and welded beam design in engineering applications further verified the superiority of the improved algorithm in addressing real-world engineering problems.

[Objective] As the core component of an aeroengine, a compressor significantly affects the flow and power of the engine. Compared with the axial compressor, the centrifugal compressor is characterized by structural simplicity, manufacturing convenience, and high single-stage pressure ratio. Therefore, the compressor is highly suitable for turboshaft engines with low flow rates and low total pressure ratios. However, the piston engine plays a more important role in the market. Accelerating the research on centrifugal compressors used in small turboshaft engines is essential.[Methods] The design methods currently used in this project include experimentation, theoretical analysis, and numerical simulation. The numerical simulation method can eliminate the requirements of experimentation, overcome measurement difficulties, and eliminate the costs associated with the experiment process. Therefore, it is a relatively accurate and efficient method for flow and transfer analysis. In this paper, according to the theory of numerical simulation, the impeller and diffuser of the centrifugal compressor are designed under specified working conditions. A three-dimensional numerical simulation of the centrifugal compressor is conducted. The influence of typical parameters on the centrifugal compressors is studied, and the parameters of the preliminary design model are optimized to obtain the ideal model of the centrifugal compressor under the design conditions.[Results] The results of this study were obtained according to the static pressure distribution cloud map and the total pressure distribution cloud map of the meridional channel surface at the highest efficiency of the centrifugal compressor and design speed conditions. The efficiency of the optimized centrifugal compressor was 0.831; the corresponding pressure ratios was 8.771, which was 3.68% higher than that of the preliminary design; and the working margin was 18.44%, which was 4.79% higher than that of the preliminary design centrifugal compressor.[Conclusions] Through the numerical simulation results of an Eckardt impeller and comparison of the simulation with reference experimentation results, the reliability of the numerical simulation of a centrifugal compressor by FINE/Turbo is proved. The results demonstrate that the kinetic energy of the gas at the impeller outlet of the centrifugal compressor is basically transformed into pressure energy and that the supercharging effect is relatively good. The entropy increase mainly occurs at the tip clearance, where the leakage flow is relatively critical. The static pressure distribution of the B2B (blade to blade) section is compared with that of the meridional flow channel. The meridional section is a contraction channel along the flow direction caused by the large turning angle of the hub. Owing to the effect of centrifugal force, a low-speed zone is developed in the flow channel to form a separation zone and result in energy loss. The separation area can be reduced through the reduction of the inlet flow angle to improve the overall performance of the compressor. The research shows that properly reducing the inlet hub ratio and the inlet angle of the impeller blade root and reasonably selecting the blade tip clearance value and the relative width of the impeller outlet are beneficial to improving the efficiency and pressure ratio of the compressor.

[Objective] The assembly of spacecraft components plays an important role in their production, and the quality and efficiency of assembly have a direct impact on the quality and efficiency of their production. Currently, spacecraft components are often constructed by hand, which results in low accuracy and efficiency. The aerospace industry's research focus is on utilizing robots to complete the assembly tasks of spacecraft components, which can improve the quality and efficiency of their production. The current assembly robots mostly use the position control mode, which measures the relative pose between the assembly features of two spacecraft components and then moves the robot to complete the robotic assembly tasks according to the measurement results. In this control mode, assembly errors are unavoidable due to measurement and robot motion errors, which will result in a huge contact force between the two contact surfaces of the spacecraft components. Excessive contact forces can damage the surface quality and coatings of spacecraft components, ultimately affecting their service lives. Therefore, the contact forces are required to be controlled by compliance control. The control parameters in the current study of compliance control are established based on the operator's experience, which is closely related to the contact forces. Because the spacecraft components are manufactured in small batches, pre-assembly cannot be used to determine the control parameters without damaging their surface quality and coatings. And improper control parameters can lead to uncontrolled contact forces. [Methods] To address this issue, a compliance control method is proposed in this paper based on the classical admittance control, which can adaptively adjust the control parameters according to the contact forces and system status. In this adaptive compliance control, the target pose and stiffness matrix are changed during the assembly process. This research examines the control effects of adaptive compliance, position, and classical admittance controls to validate the practicality of this strategy. Taking the control moment gyroscope (CMG) assembly task as an example, this research designs and develops a CMG robotic assembly prototype. The F/T sensor is installed between the CMG and the robot's end-effector to measure the contact forces during the assembly process. And Kalman filtering is utilized in this paper to filter the measurement noise of the F/T sensor. [Results] The position and orientation of the CMG were modified according to the adaptive compliance control presented in this study. After adjusting the position and orientation, the CMG's contact surface and the mounted base's contact surface were fitted together, and the contact forces of the two surfaces were guaranteed to be small. [Conclusions] The outcomes of the simulation and experiment results show that adaptive compliance control has advantages, including fast convergence, minimal residual contact force, and adaptive adjustment of the control parameters. Additionally, the adaptive compliance control suggested in this study can be quickly applied to various spacecraft component assembly tasks. This method establishes the theoretical and technical foundation for autonomous robotic assembly of spacecraft components and is expected to be employed for real-world spacecraft component assembly tasks.

[Objective] Tropical cyclone (TC) is one of the biggest threats to life and assets in coastal areas. TC is a stochastic event characterized by various hazards, such as strong wind, heavy rain, storm surge, and flooding, which can cause significant impacts individually or in combination. Exploring the relationship between the multiple attributes of TC can help estimate the severity of TC and aid in the emergency response and risk management. Strong wind and heavy rain are the two most severe hazards of TC disasters. Generally, TC weakens rapidly after landfall due to the mountainous terrains in coastal areas, and its intensity (wind) decays within a very short period. The maximum wind speed (MWS) of the TC at landfall reflects the threats posed by the strong winds of the cyclone. MWS also contributes to the rise in water levels caused by storm surges. Total precipitation (TP) can indicate the intensity of TC rainfall as well as the potential impact of inland floods and water logging. However, the relationship between MWS and TP is complex and nonlinear, and there is a lack of a clear formula to express this relationship. Copula is an effective probability method to model the dependence between two or more variables with uniform cumulative distribution functions (CDFs).[Methods] Therefore, in this study, a bivariate copula function was used to construct the joint probability of MWS and TP. Four marginal distribution models (Gamma, Gumbel, Weibull, and generalized extreme value (GEV)) were first fitted based on 553 MWSs at landfall and TPs over land in China (1951-2015). Three two-dimensional Archimedean copula functions (Clayton, Frank, and Gumbel) were then used to construct the joint probability of MWS and TP. The Kolmogorov-Smirov (K-S) test at a 5% significance level and the ordinary least squares (OLS) values were used to determine the best marginal and copula models. The characteristics of marginal CDFs and joint probability were also discussed. The conditional probability of TP was also calculated and discussed since TC intensity (wind) is easier to achieve than precipitation.[Results] The results of this study are as follows: (1) Weibull and Gamma are the best marginal CDFs for MWS and TP, respectively, and the Gumbel copula is the best copula function. Fitted Gumbel copula PDF values in the upper and lower tail are relatively high, indicating the probability of TCs with MWS and TP simultaneously being strong or weak is higher than TCs with either MWS or TP being severe. (2) The maxima of conditional probability increases with MWS, indicating that the most probable TP is also strong when MWS is strong. (3) Here, TP∈[1000, 2000]×10⁸ m³ is defined as strong TP. When MWS ≤60 m/s, the conditional probability of strong TP increases with MWS; but when MWS >60 m/s, the conditional probability of strong TP increases with MWS before the threshold and decreases with MWS after the threshold. Each TP is associated with an MWS threshold, which increases with the concerned TP.[Conclusions] Our findings show that the construction and analysis of the joint probability distribution between MWS and TP lead to an improved understanding of the interaction relationship between TC hazardous wind and precipitation. This study also contributes to a comprehensive investigation of the TC multihazard destructiveness.

[Significance] Aerospace vehicles have undergone significant modifications in terms of aerodynamic shape, flight speed, flight environment, and flight duration compared with conventional flight vehicles. They must withstand harsh aerodynamic thermal environments for long durations and maintain a sharp leading-edge shape with a high lift-to-drag ratio, imposing extremely stringent requirements on the temperature resistance, durability, structural efficiency, and reliability of the thermal protection system. Traditional thermal protection depends largely on passive methods such as heat insulation, heat sink, and radiation heat dissipation. Although the thermal protection performance of related technologies has improved, which is restricted by several constraints, such as ensuring that the prototype is safe under harsh conditions of extremely high heat flux and ultrahigh temperature along with structural stability, long-term operation, light-weight nature, and repeatability. Thus, a new active thermal protection technology is necessary. In this context, transpiration cooling technology offers the advantage of high thermal efficiency without requiring any changes in the prototype of a vehicle. It has been widely considered a potential active thermal protection technology. However, when transpiration cooling is used for thermal protection of a flight vehicle, some challenges related to the complexity of the system, a mismatch between coolant supply and demand, unstable control of the operation, and development of a high-precision prediction model etc., arise. [Progress] Research on transpiration cooling primarily focused on quick evaluation of performance, numerical simulation of flow and heat transfer, evaluation of cooling mechanism performance, development of optimal control algorithm for efficiency, and optimization of structure form and yielded beneficial results. However, several fundamental scientific issues needed to be urgently addressed to fully realize the engineering application of this technology in aerospace vehicles. In the context of numerical simulation, the accuracy and adaptability of the heat and mass transfer model should be improved. Most existing studies had mathematically described and solved the physical process of heat and mass transfer in porous media at the macroscale. But some parameters related to specific phase change heat and mass transfer (such as evaporation/condensation coefficient and fluid-solid convection heat transfer coefficient) that affect the model's accuracy must be modified through experiments, and the adaptation was partially successful. Most existing models assumed that the temperature of porous media, liquid phases, and gas phases were equal. Although a few models explored the nonequilibrium effect between porous media and fluids, they did not consider the nonequilibrium effect between gas and liquid phases. There were few flight experiments in the research and a large gap between the ground experimental test and practical use conditions. Furthermore, extreme effects related to high-temperature, real, and rarefied gases and shock wave/boundary layer interference during high-speed flight could not be effectively reproduced on the ground. Moreover, there was a lack of experimental data that could be used to verify the accuracy of the heat and mass transfer model. The experimental test method was relatively simple, and the flow and heat transfer process of the liquid in the porous medium could not be obtained. It was challenging to effectively obtain the boundary layer flow law of the liquid when it entered the high-speed mainstream flow from the porous medium. In terms of control strategy, the present research on transpiration cooling control systems lacked a transient simplified mathematical model that could be quickly established, particularly for liquid phase change transpiration cooling with the multiphase flow and phase change process. Simultaneously, there were few transpiration cooling control systems with practical engineering values based on modern control theory, which made it difficult to achieve optimal performance in practical engineering applications. Some adaptive and self-driven transpiration cooling systems had been proposed as new forms of transpiration cooling structures; however, they were still at the mechanism verification stage, and the engineering application effect needed to be verified. [Conclusions and Prospects] Follow-up research will focus on the micro/mesoscale fine numerical calculation model, advanced visual experimental testing methods, rapid response-precise control strategies, self-driven and adaptive structural engineering systems, and combined active and passive thermal protection.

[Objective] The atmosphere-breathing electric propulsion (ABEP) system has become a highly promising candidate for drag compensation in spacecraft operating in very low Earth orbit. To improve the inlet design of ABEP systems, this study performs a comprehensive numerical investigation of gas flows inside the inlet. The primary objective is to gain insight into the effects of the gas-surface interaction (GSI) model on the flow features, compression, and collection performances. [Methods] This paper explores ABEP inlet flows using the direct simulation Monte Carlo (DSMC) method. A typical altitude of 180 km in the upper atmosphere is considered, and four GSI accommodation coefficients (σ=1, 0.8, 0.5, and 0.2) are selected. The DSMC method simulates gas flows according to the motion of a cluster of simulation particles, where each particle represents a large number of real gas molecules. In the DSMC method, particle motions are computed deterministically, whereas intermolecular collisions are calculated statistically. Each simulation particle travels at a constant velocity until it collides with another simulation particle or a solid surface. In the event of an intermolecular collision, an appropriate molecular collision model is employed to compute post-collision velocities, and in the event of gas-surface collisions, a suitable GSI model is adopted to calculate the molecular velocity after reflection. In this work, the internal energy exchange is modeled using the Larsen-Borgnakke scheme. Further, the intermolecular collision is handled using the variable hard sphere model and the no time counter-collision sampling technique. The simulation is always evaluated as an unsteady flow, and a steady result is obtained as the large-time state of unsteady simulation. After achieving a steady flow, the simulation particles in each cell are sampled for a sufficient duration to decrease statistical scattering. All macroscopic field quantities (such as mass density, velocity, and temperature) and surface quantities (such as surface pressure, shear stress, and heat flux) are calculated based on these time-averaged data. [Results] Numerical results show that the distributions of gas pressure and mass flux are considerably affected by the GSI models. The lower the GSI accommodation coefficient, the higher the gas pressure and the larger the mass flux. Consequently, the GSI accommodation coefficients play a vital role in the compression factor and collection efficiency of the inlet. Furthermore, the decrease in the GSI accommodation coefficient from 1.0 to 0.2 leads to an increase in the compression factor and collection efficiency by a factor of 7 and 4, respectively. In addition, as the GSI accommodation coefficient decreases, the high-pressure region moves toward the ionization section, facilitating the ionization of neutral gas molecules. The following mechanism underlies this effect: after reflecting in a specular manner from the concave surface, the gas molecules congregate at the focus and enter the ionization section. [Conclusions] To improve the inlet design of an ABEP system, a combination of the geometric design and surface-material design should be adopted. A concave compression section should be employed, and at the same time, the inlet surface should be smoothened to decrease the GSI accommodation coefficient.

Objective: Implementing differentiated toll discounts for expressway trucks can lead to a more balanced traffic flow across the road network. Expressway operators hope to make profits by charging truck tolls, while truck groups aim to maximize profits through toll charges, whereas truck groups focus on minimizing travel costs in terms of economics and time. A balance exists between the benefits of both parties; however, determining differentiated toll discounts for expressways to reach this balance is difficult. Methods: (1) Based on consumer surplus theory, key factors affecting freight route selection are identified using the preference survey of traveling behavior, and a bi-level programming model is proposed for determining differentiated toll discounts, incorporating assumptions and constraints. (2) The upper model, considering truck cost and travel time, is a surplus maximization model for expressway operators. It is solved using a novel algorithm enhanced by combining a genetic algorithm with simulated annealing. In the upper model, a lower limit on the financial revenue targets of highway operating enterprises is included the constraints to avoid overflow of lower bound returns during the iteration process. (3) The lower model leverages a logit-based stochastic user equilibrium allocation model for multiple vehicle types under elastic demand, solved using the Frank Wolfe algorithm. A generalized impedance function considering economic and time costs is established in the lower model to demonstrate the impacts of road conditions on truck travel. Cost weighting coefficients are introduced, and calculation methods and recommended values are proposed to integrate economics and time costs. (4) Detailed execution steps are provided for solving algorithms of the upper and lower models. The model also introduces model convergence criteria to optimize the iteration efficiency of the solving algorithm. A fitness function is proposed based on the financial lower bound target, and the upper model is transformed into a minimum value problem, eliminating the constraint of discounted rates. Results: The feasibility of the model is validated using toll collection data of expressway and link traffic data of highways, with three instance highway sections. A reasonable range suitable for implementing differentiated toll discounts can attract trucks back to the expressway, and increasing the daily average traffic volume for each vehicle type. After 43 iterations, the upper model achieves a stable function value. The toll discount rates for small trucks, medium trucks, heavy trucks, and extra-heavy trucks on the instance expressway fall within the ranges of 78.68%-86.27%, 55.82%-65.82%, 47.90%-54.81% and 47.52%-48.31% respectively; consequently, the average truck flow on the expressway increases by 12.24%. Conclusions: The conclusion demonstrates that the bi-level programming model can accurately determine the toll discount range for trucks on expressways; however, even with a discount rate of 4.7% for oversized trucks on nearly 100 km of the actual expressway, attracting all oversized trucks to return to the expressway remains challenging. Fuel and toll fees remarkably impact travel path selection within the generalized impedance function; moreover, the same toll discount produces notable differences in implementation effects across truck types. The research provides support for developing differentiated toll policies for expressways, as well as their subsequent optimization and adjustment.

[Objective] Future community is a novel type of ecological low-carbon urban functional unit that follows sustainable development objectives and the sponge city construction concept. Some studies have employed different methods targeting data accessibility and technical requirements to explore future community planning. However, a systematic method is still lacking for different planning and design stages, additions to which will support the planning layout of sponge source facilities for future communities.[Methods] To integrate the future community planning methods incorporating the sponge city construction concept, a multimethod framework for the sponge source facility layout of the future community was constructed, adopting the volume capture ratio (VCR) method, the modeling method, and the multiobjective optimization method for different data and technical requirements. The results from the case study of a community to be transformed into a future community in a rainy southern Chinese city showed that the VCR method demonstrated the lowest data and technical requirements, which could generate a layout scheme meeting the volume capture ratio of annual rainfall (VCRAR). This method is particularly suitable for the early stages of the sponge source facility layout planning for limited data. However, a model was required for further assessments of pollution and carbon reduction, along with additional relevant data (drainage network, rainfall data, etc.). To achieve multiobjective comprehensive environmental benefits and the cost-effectiveness of future communities, a multiobjective optimization method could be incorporated. Nevertheless, intelligent optimization algorithms and model coupling technology were indispensable to achieve multiobjective optimization.[Results] The runoff management efficiencies of different schemes employed by these methods indicated that the sponge source facility layout scheme by the VCR method achieved approximately 80% VCRAR. The VCR-based scheme was further evaluated by the Storm Water Management Model (SWMM), demonstrating a decline in the runoff peak flow from 5.65 m³·s^-1 in the traditional scheme (without sponge facilities) to 2.17 m³·s^-1, and the VCRAR changed from 51.87% in the traditional scheme to 79.43%. A 21.69%—30.52% reduction in the peak concentrations of total suspended solids, nitrogen, phosphorus, and chemical oxygen demand and a 284.87 t·y^-1 carbon reduction over the traditional scheme were recorded, exhibiting significant pollution and carbon reduction improvement of the VCR-based scheme. The multiobjective optimization scheme based on the multiobjective optimization method by coupling SWMM and NSGA-II aimed for the best cost-effectiveness, which resulted in a 3.29% and a 1.51% decrease in the green roof and the sunken greenbelt area, respectively, and a 2.13% increase in the permeable pavement area, as well as an 18.67% reduction in the cost compared to the VCR-based scheme. Thus, the increased area of permeable pavement made it the preferred choice. Moreover, the multiobjective optimization scheme displayed superior peak flow reduction (21.20% decrease), peak concentration reduction of different pollutants (6.32%-16.67% decrease), rainwater reuse rate (1.17%-2.65% increase), and carbon reduction (7.91%-12.66% increase) over the VCR-based scheme. However, in the multiobjective optimization scheme, the increase in the permeable pavement area increased the carbon emission by 178.40 t as compared to the VCR-based scheme.[Conclusions] Utilizing the carbon emission indicator as a control objective in the optimization process is necessary for future studies. Nonetheless, the multiobjective optimization scheme achieved higher net carbon reduction benefits due to higher annual reductions and needed about seven years to achieve carbon emission recovery. Briefly, the VCR method has a simple and easy operation, and it can meet the requirements of future community planning and runoff control objectives, while the multiobjective optimization method can achieve the best environmental benefits and cost-effectiveness.

[Significance] Climate change is the primary challenge that intensely affects sustainable human development. The transport sector has been one of the major sources of carbon emissions and is considerably affected by climate change. Because of the growth of China's economy and total transport demand, transport-related carbon emissions are also gradually increasing. Moreover, frequent complex and extreme climate events with clear regional differences have negatively affected the construction, maintenance, and operation of the transport infrastructure. Therefore, China's transport sector needs to reduce carbon emissions for green and low-carbon developments and improve its adaptability and resistance to various adverse climatic conditions. However, China's transport sector still faces many challenges in mitigating and adapting to climate change, and its policy tools, measures, and basic capacity to cope with climate change need to be enhanced. Therefore, transport sector-related strategies and routes to adapt to climate change need to be explored. [Progress] First, the policies and measures implemented in different countries to address climate change were introduced from the perspectives of mitigation and adaptation. Second, the advancements made by China's transport sector in mitigating climate change were summarized from the perspectives of the construction of green and low-carbon transport infrastructure, optimization of the transport structures, and promotions and applications of new and clean energy. The measures implemented to adapt to climate change in China's transport sector were summarized from the perspectives of improving the adaptability of the transport infrastructure, strengthening the monitoring and warning systems of climate change, and managing risk. Third, the interactions between each subfield and sublink of the transport system and climate change, as well as the main measures implemented to mitigate and adapt to climate change in the transport sector, were analyzed. Finally, key areas, strategies, and methods to mitigate and adapt to climate change were proposed. [Conclusions and Prospects] Analysis results are provided and discussed. First, the current plan for China's transport response to climate change needs improvement. The capacity to respond to climate change has not been planned at the subfield and sublink level of the transport system. For mitigating climate change, carbon emissions reduction measures, such as the promotion of new energy vehicles and ships, as well as the optimization of the transport structure, are inadequate. Furthermore, the assessment of the effects of the transport infrastructure on climate change is still in its infancy. Second, the direction of the transport system's development should be combined with the strategic requirements of mitigation and adaptation to climate change. Third, in the transport field, the infrastructure, equipment, and transport structure should be improved; moreover, the infrastructure should be adapted to climate change, and emergency support of transport equipment and transportation organization in extreme weather should be optimized to enhance the capability to adapt to climate change. Finally, the following measures are proposed: Mitigation and adaptation to climate change should be jointly and appropriately implemented to comprehensively address climate change in the transport sector. Greenhouse gases and air pollutants should be jointly controlled to realize the goal of “double carbon”. Adaptation to climate change should be applied in conjunction with ecological protection and restoration to strengthen the capacity of the transport sector to adapt to climate change.

[Objective] Reliable risk assessment results can help to improve the efficiency of safety management in gas pipeline networks. The Kent method is widely used as an accepted risk assessment method. However, relevant literature suggests that the Kent method is inadequate in the determination of weights, scoring items, and scores, and the determination of index weights and scoring criteria requires expert experience, which is highly subjective. Therefore, the traditional Kent method needs to be improved to comply with the risk assessment of different gas pipeline networks. To improve the objectivity and accuracy of risk assessment of gas pipeline networks, a quantitative risk assessment method based on the fuzzy analytic hierarchy process-improved coefficient of variation (FAHP-ICV) for gas pipeline networks is proposed.[Methods] In this work, based on data from the gas pipeline networks and their surroundings, the traditional risk assessment method for gas pipeline networks was improved in terms of index system and weighting and scoring criteria determination using statistical methods. First, a risk assessment index system comprising three primary indicators and nine secondary indicators was constructed while considering the actual operation of the gas pipeline networks in a province. Second, the subjective weighting method represented by the hierarchical analysis method and the objective weighting method represented by the coefficient of variation method were improved. The fuzzy hierarchical analysis method was used instead of the traditional one, and the improved coefficient of variation method was used to modify the weighting results of the original coefficient of variation method. The two methods were combined to determine the comprehensive weights of the evaluation indicators based on expert experience and the inherent rules between the indicator data. Next, based on the K-means clustering and sampling techniques in statistics, the sample data for the pipe section were determined and pre-processed through probability analysis to determine the upper bound of the scores of evaluation indicators. Then, the final scoring criteria were determined by integrating expert reports. Finally, a linear integrated assessment method was used to calculate the relative risk values of the pipe sections to achieve risk ranking and classification.[Results] To analyze the distribution of risk classes across gas pipe sections in the cities, the relative risk values of gas pipe sections in 12 cities were calculated and compared with the risk class classification criteria. For example, in city four, a comparison between the distribution of risk classes across gas pipe sections and the local map showed that the overall risk of the city was relatively high. The average risk values for gas pipe sections and different level indicators were compared between 12 cities; four cities were found to have great risk, and one city was found to have significant risk. Furthermore, cross-analysis was carried out on the city where the inspection and maintenance indicators suggested not fulfilling the requirements of gas pipe inspection regulations.[Conclusions] The feasibility and applicability of the method were verified through examples, providing new ideas and methods for the quantitative risk assessment of gas pipeline networks.

Because of favorable wind resource conditions and a lack of land occupation limitations, offshore wind power has been gaining an increasingly important role in the global energy strategy. However, scour is a widespread problem around offshore wind power foundations, resulting in a decrease in foundation bearing capacity, changes in structural natural frequency, and submarine pipeline exposure. As a result, monitoring and early warning of scour are essential. This study studied the scour process and its dynamic characteristics before proposing a method for identifying the scour initiation in design. For scour monitoring, multibeam sonars, the most often used scour measurement method, have problems of high cost and discontinuous operation, making it impossible to provide on-site scour data in a timely manner. Herein, a method for scour monitoring using structural vibration frequency is proposed. Then, based on ABAQUS, an integrated model of a wind turbine tower foundation was established to study the correlation between the scour depth and the first-order natural frequency, and the feasibility of using the structural vibration frequency to estimate the scour depth. As a result, a scour monitoring method and system based on low-frequency vibration data were developed. The data is acquired in real time by vibration sensors installed in specific parts and processed using a fast Fourier transform after data filtering to obtain the time-domain and frequency-domain characteristics necessary to determine whether the scour is normal. The numerical simulation results revealed that the first-order frequency of the structure was basically linear with the scour depth and that the frequency decreased by 0.009 3 Hz (3.3%), 0.017 2 Hz (6.3%) and 0.027 0 Hz (10.2%) for the scour depths of 3.0 m, 6.0 m and 9.0 m, respectively, compared to the scour-free condition (0.281 2 Hz). The monitoring data from an offshore wind farm in Jiangsu revealed that: (1) The installation orientation and height of the vibration sensors had essentially little effect on the first-order frequency; however, the vibration amplitude decreased as the installation elevation drops. (2) The variations of scour depth and frequency were basically consistent with the numerical results: the scour depths of turbine units #7, #15 and #17 increased from 3.47 m, 5.21 m and 6.11 m in September 2019 to 5.12 m, 5.48 m and 6.95 m in April 2020, while their vibration frequencies decreased from November 2019 to July 2020 by 0.001 3 Hz, 0.001 1 Hz and 0.002 3 Hz, respectively. Due to the lack of monitoring data, the frequency and scour depth do not fully correspond in time and space. There is an inconsistency between the change in frequency and scour depth of different units, but the monitoring data of all units show that the correlation between the two is clear. As a result, this paper suggests that when the frequency drops by more than 0.010 0 Hz in operation, the system will issue an early warning message prompting the cause of the accident to be investigated. The paper further discussed the future direction of the scour monitoring improvement, and the study results can be used as a reference for similar projects worldwide.

[Objective] Bridge anchorage core concrete, a typical mass-filling marine concrete structure, faces challenges in temperature change control and crack prevention due to its special shape, continuous casting, and complicated boundary. [Methods] Based on the mass-filling concrete of the Guangxi Longmen Bridge anchorage basement (58 606 m³), this paper conducts an online monitoring and analysis of the real thermal field and stress distribution according to the evolution mechanism of the concrete temperature gradient during the pouring period. This work includes developing a temperature gradient digital monitoring system to provide feedback on the deviation from the actual value and provide a basis for timely warning and dynamically adjusted accurate temperature control, proposing the cracking control gradient index as the space and time gradient indices (a dimensionless index), and reconstructing the temperature field to the evolution of the real thermal field base on the temperature measurements in concrete, which is of great importance for the cracking control of the concrete structure. [Results] The main study results are as followed: (1) A major challenge in concrete cracking control was investigated according to complex structural properties, the continuous casting method, high temperature, high humidity, strong wind, and a high salt mist environment. (2) The monitoring data of the temperature gradient digital monitoring system indicated a certain difference in the temperature development in the center concrete and the area near the surface. The temperature in the concrete central area underwent a rapid increase and tended to be stable, stabilised temperature range of 53.60—54.50 ℃, and the temperature increase reached 88.16%—99.34% of the adiabatic temperature increase. The temperature near the concrete surface underwent a rapid increase and a slight decrease, peaking at 52.90 ℃. (3) The threshold values of the space gradient and time gradient indices were defined as -3.00—3.00 ℃/m and 0.002 h^-1·m^-1, respectively. The temperature gradient index met the threshold requirement, the horizontal and vertical spatial temperature gradients at the stable stage were -0.15—0.14 ℃/m and 0.29—1.08 ℃/m, respectively, and the time-temperature gradient was within 0.002 h^-1·m^-1. These results indicated that the concrete heat exchange process was performed as small temperature changes in time and space. (4) The temperature field reconstructed from the monitoring data revealed that the real temperature gradient characteristic of the mass-filling concrete and isotherms was dense near the pile foundation at 96 h, then gradually became sparse, and the time-temperature and space gradients gradually became uniform and remained uniform after 144 h. (5) The evolution of the real thermal field, from a nonuniform distribution to a uniform distribution, could be divided into three stages, i.e., thermal accumulation, thermal release, and thermal transfer. The concrete internal stress simulation indicated that the maximum tensile stress occurred at the stress concentration zone along the intersection of the circumferential pile foundation and was substantially affected by environmental temperature change. The maximum tensile stress value was 1 780.0 kPa, and the corresponding safety factor was 1.03, satisfying the design requirements. [Conclusions] A case study shows that the temperature gradient digital monitoring system successfully supports the dynamically adjusted temperature control and effectively controls the cracking risk. These study results can be used as a reference for the cracking control of similar projects.

[Objective] The pipe section collection time is typically based on the theory of steady full pipe uniform flow when using the reasoning formula method to calculate the design flow of a storm pipe network, but the actual water flow in the storm pipe is non-steady, causing errors in the calculation of the design flow that, when applied to a larger scale pipe network, gradually reduce the calculation accuracy. In this context, the paper suggests a design flow computation method for storm pipe networks based on kinematic wave simulation. [Methods] In this paper, the design flow of pipe sections is solved using kinematic waves under the condition of ensuring the equivalent setup of model parameters and storm pipe network starting design parameters. This paper combines the Horton infiltration model and the φ index method to calculate infiltration intensity in the surface rainwater runoff stage. The runoff generation is calculated with the objective of achieving equivalence of the volumetric runoff coefficient and discharge runoff coefficient. Taking surface catchment time and linear confluence curve type as input, and coupling with the isochrones model, the equivalence setting of design conditions and stormwater outlet inflow process line calculation are completed. In the pipe section confluence process, the pipe section flow process line is calculated by inputting the corresponding stormwater inlet inflow process line into the node inflow mode and computing the pipe section confluence process using the stormwater management kinematic wave model. The stormwater inlet inflow process line of the designed pipe section and the upstream pipe section flow process line connected with it are superimposed to complete the calculation of the pipe section design flow process line. Combined with the hydraulic design of the stormwater pipe section, the whole storm pipe network design is realized based on the geospatial data abstraction library development technology process. [Results] The results of a storm pipe network example in a particular area (with a total size of 4.506 km²) showed that: (1) When compared to the reasoning formula method, the stormwater pipe section created using the kinematic wave simulation approach had a quick catchment time and a greater design flow rate. (2) The flow calculation difference between the two approaches increased over time as catchment time and catchment area increased, reaching a maximum increase of 39.45%. (3) Under the 10-year rainfall scenario, the design storm pipe network obtained by the two calculation methods of equivalent design conditions reduced the number of overflow nodes, total overflow volume, and length of pipe section overload by 8.57%, 28.57%, and 38.48%, respectively, compared to the reasoning formula method. [Conclusions] By comparing the differences in the design results obtained by the two calculation methods for different catchment times and catchment areas, it can be seen that for large projects, it is advisable to use the kinematic wave simulation method to calculate the design flow of the storm pipe network. In a simulated analysis with a 10-year exceedance of rainfall, the storm pipe network designed by the kinematic wave simulation method has better flood prevention performance.

[Objective] The monitoring value of surrounding rock displacement has the characteristics of complexity and nonlinear dynamic change, and the static one-time learning of previous optimization algorithms combined with a single regression model cannot be practically applied in real scenarios. The regression fitting model uses several displacement monitoring point data to construct a general model of the surrounding rock displacement change, which cannot be applied to predict the future changes in monitoring points. The autocorrelation of the surrounding rock displacement data makes it more practical as a time series prediction problem. However, the generalization performance of a single model is easily disrupted by historical monitoring data, resulting in inaccurate prediction of test applications. In this study, a dynamic prediction method for surrounding rock displacement time series combined with time series monitoring data preprocessing is proposed. [Methods] First, the displacement monitoring data of the tunnel-surrounding rock are preprocessed. The intercepted stability monitoring data are isometrized by cubic spline interpolation, and the monitoring data are decomposed into trend and random term displacement components by variational mode decomposition signal processing. Adaboost integrates 10 long short-term memory networks to construct an integrated optimization model for time series prediction. Then, the weights of the training samples are initialized, the weight coefficients of the base model in the integration are calculated by training the first base model, and the weights of the training samples of the next base model are updated. Finally, the weight coefficients of all base models are obtained. After Adaboost integration optimization, the prediction results are calculated using all base models and their weight coefficients. After training and learning, single-step dynamic prediction is performed, and monitoring changes are updated in real time to model learning. The cumulative displacement prediction results can be obtained by superimposing the trend and random term displacement sequences using the time series decomposition principle. [Results] The displacement components of the rock surrounding the Central Yunnan Water Diversion Project were predicted and superimposed, and three displacement data were obtained. Compared with the traditional time series prediction model, each displacement index exhibited good performance. The complete data of the surrounding rock displacement time series were obtained by the FLAC 3D numerical simulation engineering section, and the application performance of the integrated optimization model was verified. Results showed that the integrated optimization model exhibited good performance in each component and cumulative displacement and was less affected by deformation rate fluctuation than the traditional model. [Conclusions] After preprocessing the time series data, the influencing factors of surrounding rock displacement and deformation are decomposed, and multiple time series prediction models are integrated for single-step dynamic prediction, which improves the shortcomings of previous studies. The correction determination coefficient and symmetrical average absolute percentage error are used as performance indicators to verify that the prediction accuracy achieves the expected goal and is superior to the traditional classical model in solving the time series problem, which promotes the predictability of surrounding rock displacement in practical applications.

[Objective] Named entity recognition (NER), a central task in the information extraction realm, aims to precisely identify various named entity types in textual content, including personal names, locations, and organizational names. In Chinese NER domain, deep learning techniques are crucial for character and vocabulary representations and feature extractions, yielding remarkable research achievements. Common deep learning models for NER include sequence labeling, span-based approaches, generative methods, and table-based strategies. Nevertheless, this task suffers from the scarcity of lexical information. Hence, this challenge is perceived as a primary hindrance limiting the development of high-performance Chinese NER systems. Despite developing extensive lexical dictionaries encompassing rich vocabulary boundaries and semantic insights, effective incorporation of this lexical knowledge into Chinese NER task remains a considerable challenge. Particularly, the seamless integration of semantic information from matching vocabulary and its contextual cues into Chinese character sequence remains intricate. Moreover, ensuring the accurate delimitation of named entity boundaries is still a remarkable concern. In the realm of intelligent judicial systems, the NER task within legal documents has garnered significant attention. Nonetheless, prevailing sequence labeling models predominantly rely on character information, constraining their capacity to capture semantic and lexical contextual nuances and inadequately addressing entity boundary constraints. To resolve these challenges, this paper introduces an innovative model called semantic and boundary enhanced named entity recognition (SBENER). To enhance the semantic features of legal documents within the SBENER model, external information containing vocabulary pertinent to theft crimes is smartly integrated. Initially, word vectors for theft crime terms are acquired through pretraining. Subsequently, a vocabulary dictionary tree is constructed, enabling the potential vocabulary candidate identification for each character. Further, these candidates are amalgamated into a final external information vector via a bilinear attention mechanism. Additionally, a linear gating structure is introduced to mitigate interference from external information in the original text. To overcome the limitations of sequence labeling models for managing entity boundary constraints, this study designs a boundary pointer network within the model to confine entity boundaries. This involves embedding the character sequence into hidden layer representations via bidirectional long short-term memory followed by decoding to introduce probability constraints for each entity span. Ultimately, contextual and boundary information is inputted into a conditional random field for obtaining the ultimate entity classification outcomes. This design adroitly tackles the issues of vocabulary loss and boundary constraint scarcity within sequence labeling models. Experimental results on the CAILIE 1.0 and LegalCorpus datasets corroborated the effectiveness of the proposed method, yielding F₁ scores of 88.70 % and 87.67 %, respectively, surpassing other baseline models. Additionally, the study conducted ablation experiments to validate the effectiveness of each component. The experimental results showed that integrating external semantic information related to theft, enhancing entity boundary constraints through pointer networks, and incorporating gating mechanisms to restrict irrelevant information fusion were all effective approaches for achieving higher F₁ scores for the model. Furthermore, this paper applied dimensionality reduction to external semantic word vector information and conducted experimental analysis on different fusion layers. Single-layer fusion outperformed multilayer fusion, while fusion at intermediate levels yielded better results. This underscored the marked enhancement in judicial NER facilitated by the proposed approach. The SBENER model effectively enhances the proficiency of recognizing named entities in legal documents through the fusion of external information and reinforcement of boundary constraints. This pioneering method substantially contributes to advancements within the intelligent judicial systems.

[Objectives] The South-to-North water diversion project is a strategic project in China. Since its construction, it has become the main source of water conservancy in more than 280 cities.The diversion tunnel is the key building to support the South-to-North water diversion project. Due to its long line, large diameter, high water pressure, complex surrounding rock geology, as well as many years of water conservancy erosion, biochemical substances erosion, geological effect and other influences, typical defects such as cracks, collapse, exposed steel bars are prone to occur. Artificial detection of defects in the tunnel not only consumes time and energy, but also has low accuracy and timeliness. Therefore, underwater robot inspection technology has become a hotspot of current research.Among them, the underwater manipulator can not only be installed on the underwater vehicle, but also can be selectively installed on the required platform to complete the tasks of cleaning the water surface, laying and repairing cables, salvaging sunken objects, cutting off ropes and so on. However, the control of the underwater manipulator is more complicated and difficult due to its time-varying mechanics, nonlinear properties, external interference and hydrodynamic influence. The main purpose of this paper is to establish the dynamics model of the underwater manipulator and improve the accuracy of the trajectory tracking of the manipulator. [Methods] In this paper, a modeling method combining Newton-Euler equation and Morrison's dynamic model is proposed, and then the dynamic parameters are identified. Then, in order to improve the precise control ability of the manipulator in complex transient underwater environment, an adaptive sliding mode control method is designed based on compensating nonlinear dynamics model and using radial basis function (RBF) neural network to compensate the unmodeled and modeling errors of the system. Through the dynamic modeling in Section 4, a detailed dynamic simulation environment of the underwater manipulator is obtained. Gaussian noise errors with amplitudes of 5, 20, 15, 10, 8, and 5 N·m are set for each joint. On this basis, Experiment 1(P1): double loop proportional integral differential (PID) controller is designed for control simulation. Then, in experiment 2(P2), RBF neural network is used to make fitting compensation for system modeling errors and unmodeled items. In experiment 3(P3), dynamic model compensation is added on the basis of P2. [Results] The trajectory tracking effect ratio of P2 and P3 was obviously better than that of P1 experiment, and the tracking effect of P3 experiment was also better than that of P2 experiment after compensating the dynamic model. [Conclusions] Through simulation, this paper has proved the effectiveness of the proposed hydrodynamic modeling of the manipulator, and on the basis of compensating nonlinear dynamic model, The adaptive sliding mode control method using RBF neural network to compensate the unmodeled and modeling errors of the system has higher trajectory tracking accuracy than the traditional PID control and the general RBF network adaptive sliding mode control.

[Objective] The resilience of transportation networks is a prominent research area in transportation safety. However, current studies on transportation network resilience often inadequately measure the changes in spatiotemporal travel costs for passengers, primarily focusing on the recovery phase rather than the resistance phase in two-stage resilience. There is also insufficient identification and analysis of critical segments, and a lack of suitable resilience simulation and evaluation methods for urban agglomeration railway passenger transport networks. This paper proposes a resistance resilience assessment model and a resistance resilience simulation evaluation process for urban agglomeration railway passenger transport networks centered on spatiotemporal accessibility for passengers. The aim is to evaluate the resistance resilience of these networks and identify critical segments. [Methods] This paper explores the concepts of resistance resilience and recovery resilience within transportation networks. Utilizing the complex network Space L modeling method, this paper develops a spatiotemporal weighted urban agglomeration railway passenger transport network model that considers actual railway passenger stations as network nodes. Segment interruption scenarios were simulated using attack modes involving single segment deletion and multiple segment continuous deletion. A dynamic resistance resilience evaluation index termed the network performance retention rate, was introduced based on the performance response function and spatiotemporal accessibility of passengers. This paper devises a resistance resilience assessment model and simulation evaluation process to evaluate the substitutability of segments and the overall network resistance resilience. The Chengdu—Chongqing urban agglomeration was selected as a case study to identify and compare critical segments and resistance resilience across unweighted, spatially weighted, and temporally weighted railway networks. [Results] The results of this paper were as follows: (1) The interruption of critical segments near railway hub cities could lead to a maximum network performance loss of 12.23%. It was necessary to identify critical segments through predisaster simulations. (2) Significant differences were found in the critical segments identified through resistance resilience simulations across unweighted, spatially weighted, and temporally weighted railway networks. The Spearman correlation coefficient indicated a relatively poor correlation between the critical segment rankings of unweighted and weighted railway networks. (3) The resistance resilience indices of the three railway networks highlighted that single segment interruptions significantly affected travel time. (4) Continuous interruption of identified critical segments severely affected network performance, with temporally weighted railway networks experiencing a stronger impact than spatially weighted and unweighted railway networks. Predisaster simulations solely based on topological structure or spatial distance might underestimate the consequences of risk interference. [Conclusions] The methods proposed in this paper address the gap in targeted research on the resistance resilience of railway passenger transport networks in urban agglomerations. Simulations of single segment interruption and multiple segment continuous interruption enable the identification and verification of key network segments. Additionally, analyzing the network resistance to interruptions provides a scientific foundation for transportation network planning and decision-making. Furthermore, analyzing the network's resilience evaluation index of the network performance retention rate proposed in this paper offsets the impact of disturbance time uncertainty, providing a scientific foundation for transportation network resilience research.

[Objective] Laser profilers are widely utilized in various fields owing to their high precision, noncontact, and low cost. However, the lens plane for traditional laser profilers is parallel to the imaging plane. Thus, the high-precision measurement range of a traditional laser profiler is limited by the camera's restricted depth of view. To address this issue, this study optimizes the traditional laser profiler design and proposes a calibration method. [Methods] Specifically, this study establishes a constant focus optical path in the laser profiler by tilting the lens to meet the Scheimpflug condition, wherein the imaging, lens, and light planes intersect in a single line, called the Scheimpflug line. Furthermore, the traditional imaging model is not suitable for the detection principle of the laser profiler; hence, the corresponding calibration ideas must be improved and optimized. This study proposes a complete and effective calibration method for the laser profiler, which can be divided into two parts: camera calibration and light plane calibration. For the camera calibration part, a tilt camera imaging model is established based on the traditional camera imaging model using a two-dimensional tilt angle. A method of obtaining the initial parameters and a nonlinear optimization process for the parameters are presented to rapidly obtain the tilt camera imaging model parameters. For the light plane calibration part, a calibration target, which has a double-step shape, is designed. Precise subpixel coordinates of the feature points on the laser profiler are obtained through image processing algorithms by collecting the contour image of the calibration target once the laser profiler is used. The light plane parameters are acquired using the subpixel coordinates for the least squares fitting, which quickly completes the light plane calibration. This study also designs a three-degree-of-freedom automatic calibration device to address various issues, including the removal of the laser profiler's filter, the manual adjustment of the laser profiler's pose, and the complex operating procedures in traditional calibration experiments. [Results] This study used the automatic calibration device to complete the calibration and accuracy evaluation experiments and verify the correctness and effectiveness of the proposed scheme. The experimental results revealed of the following: (1) The laser profiler designed herein could clearly capture all the feature points on the light plane, thereby effectively solving the limited measurement range problem of the traditional laser profiler. (2) The reprojection errors of the laser profiler's camera were 0.487 with the traditional camera calibration method and 0.129 with the camera calibration method. (3) The calibration target could complete the light plane calibration by collecting only one image according to the expected goal. (4) After completing all the calibration steps, the average detection deviation of the laser profiler for measuring the size of the standard ceramic gauge block was approximately 0.028 0 mm. [Conclusions] Thus, this study significantly improves the profiler's high-precision measurement range by establishing a constant focus optical path in the laser profiler. A calibration method with higher accuracy and efficiency is proposed herein for the laser profiler. The detection accuracy of the calibrated laser profiler meets the actual industrial requirements.

［Objective］ Accidental fires seriously threaten the safe operation of aircraft. Air transportation environments typically have low ambient pressures that can significantly influence the occurrence and spread of fire. The wallboards in civil aircraft are generally made of composite materials. The Federal Aviation Administration of the United States and the Civil Aviation Administration of China require that the fire resistance characteristics of these materials be experimentally verified. This study investigated a sandwich structure panel (panel A) and a laminated panel (panel B) of an Airbus aircraft to understand the influence of ambient pressure on aircraft fires and to enable the earliest possible detection, management, and prevention of aircraft fires at the low ambient pressures typically encountered in such situations. Panel A was composed of upper and lower resin base panels, with an aramid honeycomb core and adhesive middle layer, whereas panel B was a resin-based glass fiber-reinforced laminate. ［Methods］ The effects of ambient pressure on the thermal insulation, ignition time, mass loss, and smoke characteristics of the panels A and B were studied using self-built, low-pressure, oxygen-enriched combustors in Kangding, Sichuan Province (61 kPa) and Guanghan, Sichuan Province (96 kPa), respectively. The thermal insulation characteristics of the panels were studied by measuring the temperature on the back surface of the panel after heating the front surface for 60 s with a heating rod. The effect of pressure on the convective heat loss was studied using the ideal gas relation. The mass loss during the fire was recorded by an electronic balance, and the smoke generation was recorded in real time by a smoke analyzer. ［Results］ The temperature of the back surface of panel A was 692.3 ℃ at atmospheric pressure and 512.4 ℃ at low pressure with a decrease of about 26.0%. The temperature of the back surface of panel B at normal and low pressures was 810.5 ℃ and 820.9 ℃, respectively. Furthermore, the temperature variation as a function of time was almost the same under either pressure condition for panel B, indicating that changes in the ambient pressure in the range studied had almost no impact on the insulation of panel B. The heating rate of panel B was higher than that of panel A, demonstrating the superior thermal insulation performance of panel A. Regarding the effect of pressure on the convective heat loss, the measured ignition times were in good agreement with the analytical model. The ignition time for panel A was reduced from 24.16 s to 20.34 s, i.e., reduced by 16%. Pressure variations had less influence on the ignition time for panel B. Variations in the pressure affected the rate of combustion; the mass loss for panel A decreased from 8.7% to 4.9%, and the peak mass loss rate decreased from 68.7×10^-3 g·s^-1 to 22.8×10^-3 g·s^-1, whereas the mass loss for panel B decreased from 5.8% to 4.8% and the peak mass loss rate decreased from 35.0×10^-3 g·s^-1 to 12.5×10^-3 g·s^-1. The time of the maximum O₂ consumption and the time of the CO and CO₂ production peaks of either kind of panels were almost the same under different pressure environments, whereas the maximum O₂ consumption and CO and CO₂ production peaks in the low-pressure environment were higher than those at atmospheric pressure. ［Conclusions］ This preliminary study on the effect of pressure on the combustion characteristics of aircraft panels finds that pressure has a significant impact on the occurrence and spread of aircraft fires. This study can provide theoretical support for cabin fire prevention and fire rescue under different pressure environments.

[Objective] The increasing maturity of large language model technology has facilitated its widespread application in downstream tasks across various vertical fields. Large language models have exhibited beneficial performance in text summarization tasks in general fields, such as news and art. However, the highly specific language style in the judicial field and the unique complexity of judicial documents in terms of structure and logic make it difficult for large language models to generate judicial document summaries. This study aims to combine prompt learning with large language models to explore their performance in summarizing judicial documents. Prompt templates containing structural information and judicial documents are used as inputs for fine-tuning large language models. As a result, large language models can generate judicial document summaries that adhere to judicial language styles and the structural and logical complexities of judicial documents. [Methods] This study proposes a judicial document summary method that combines prompt learning and the Qwen large language model. Judicial document data are used as the input for fine-tuning a large language model using supervised fine-tuning technology to enhance its applicability in the judicial field. Simultaneously, prompt templates that incorporate structural information and role instructions are designed to optimize summary generation to more accurately reflect the structural characteristics and logical relationships of documents. According to the characteristics of the pretraining data format of the large language model, the fine-tuning data were constructed in the form of question-answer pairs. [Results] The experimental results show that the proposed method improves the F1 of the baseline model by 21.44%, 28.50%, and 28.97% in ROUGE-1, ROUGE-2, and ROUGE-L, respectively, and exceeds all of the comparison models. The ablation experiment demonstrated that the summary generation method using prompt learning was superior to the method without prompt learning for all indicators, and the performance of summarization generated by the large language model utilizing prompt learning was significantly enhanced. The case demonstration reveals that after prompt learning is used to enhance the perception of structural information in the judgment document by the large language model, the judgment document summary generated by this model can better capture and retain key information in the judgment document. Moreover, the language style of this model is closer to that of a real judgment document summary, which further illustrates the effectiveness of the proposed method. [Conclusions] This study integrates the structural information of a judgment document into the task of generating a judgment document summary using a large language model in the form of prompt templates. Prompt templates containing structural information are used to assist the large language model in summarization generation. Therefore, the model can focus on the key information in the judgment document and capture deeper semantic logical relationships. The results demonstrate that after fine-tuning the large language model with judicial document data and introducing structural information, the model demonstrated excellent performance and great application potential in the judicial document summary task. The proposed method can effectively enhance the capability of a large language model in the field of judicial document summaries.