Abstract:This paper investigates the research progress of digital twin and proposes a novel digital twin concept framework for underground engineering. The digital twin maturity grading method is analyzed， and a five-level progressive developed digital twin maturity grading composed of description， reflection， prediction， control and fusion is proposed. Based on extensive literature research， a maturity impact factor system is developed， and a digital twin maturity evaluation model （DTMM） is proposed based on an optimized decision experimentation and evaluation laboratory （DEMATEL） and analytic network process（ANP）joint method for evaluating the degree of cause， centrality and dependency. Finally， the DTMM is applied in conjunction with an underground project， and the results proved that the method proposed in this paper is applicable to underground projects and has implications for the development of digital twin in underground engineering.

Abstract:Based on the equivalent continuous model， this paper deduces the longitudinal equivalent bending stiffness of rectangular shield tunnels under the combination state of compression and bending. Considering the cross-sectional characteristics of rectangular shield tunnels， the closed-form solution of the equivalent bending stiffness under four neutral axis positions is discussed， based on which， a parametric analysis， using the new analytical solution， is conducted to investigate the effect of key parameters on the longitudinal bending stiffness， including the ratio of compression to bending， the number of bolts， the ratio of width to thickness and so on. The critical value of N-M ratio for different positions of the neutral axis is further obtained. The results show that the longitudinal bending stiffness efficiency increases with the increase of the compression-bending ratio， the number of bolts and the ring width-to-thickness ratio， but decreases with the increase of the sectional width-to-thickness ratio and aspect ratio. The position of the neutral axis is not only related to the size of the cross-section and material properties， but also to the compression-bending ratio. The critical value of N-M ratio decreases with the increase of sectional width-thickness ratio and is sensitive to the change of sectional shape. The conclusion has important theoretical reference for optimal selection and design calculation of rectangular segments.

Abstract:The mechanical properties of 3D printed fiber-reinforced concrete with recycled aggregate show significant anisotropy， which is closely related to meso-pore structure and interface region. Based on the visualization analysis of 3D printing concrete samples by computed tomography(CT）， the porosity of 3D printed recycled concrete samples is ellipsoidal. The average pore compactness of 3D printed recycled concrete is significantly lower than that of mold-casted samples. The addition of polyethylene fiber and basalt fiber leads to the decrease of the mean compactness. Meanwhile， the ratio of pore length and Z-axis in 3D printed recycled concrete samples is as high as 58.0 % at orientations between 60°to 90°， which is much higher than that of mold-casted samples with the same mixture. Fiber addition also affects the pore orientation of 3D printed recycled concrete. The pore in the vertical to Z axis has increased for polyethylene fiber 3D printing recycled concrete specimens， while that has decreased for basalt fiber 3D printing recycled concrete specimens.

Abstract:Land resources are gradually becoming limited due to urbanization and climate change. The advent of floating structures provides new opportunities for bolstering maritime capabilities and promoting eco-friendly urban development. The use of floating concrete structures in public buildings， renewable energy facilities， and transportation infrastructures is summarized in this paper. Floating structures efficiently expand landmass， shorten construction period， reduce costs， and minimize impacts on the ecology. Moreover， three technical aspects of floating structures are given， including kinematic and mechanical analysis， safety verification， and module design. Furthermore， based on the overall evaluation， it is recommended to improve the sustainability of floating structures from three approaches structure reuse， material recycling， and optimized design of composite concrete floating structures. Correspondingly， the applications of recycled aggregate concrete， seawater sea-sand concretes， and composite concrete structures are suggested in building floating structures.

Abstract:The large-scale storage of unstable renewable energy has great potential. Therefore， a heat storage heat pump system for tunnel surrounding rock is proposed， and a 3D heat exchanger coupled model in tunnel surrounding rock is developed. Additionally， an optimization method for heat storage performance of tunnel surrounding rock heat pump system is proposed using Taguchi design， and applied to the Stuttgart-Fasanenhof energy tunnel project. The rationality of the model is well verified by on-site thermal response test data， and the simulation results of the heat storage performance of the thermal tunnel show that， the heat storage efficiency of the tunnel surrounding rock heat storage heat exchanger system is at least comparable to that of the traditional vertical borehole heat exchanger heat storage system， Moreover this system reduces the high borehole construction costs and minimizes the required underground area. Four operating parameters for the heat storage tunnel at three levels are assumed， and L₁₀（3⁴） orthogonal array is employed. The optimal control parameter combination and the contribution rate of each parameter are obtained by conducting signal-to-noise ratio and ANOVA analysis using Minitab statistical analysis software. The maximum percentage contribution is observed in factor D （heat storage and extraction temperature difference）， followed by the operating ratio， the initial temperature of the surrounding rock and the thermal conductivity of the surrounding rock， respectively. The optimal parameter combination is obtained， i.e.， the initial temperature of the surrounding rock is 18 °C， the thermal conductivity of the surrounding rock is 1.5 W·m^－1·K^－1， the operating ratio is 1：2， and the temperature difference between heat storage and extraction is 45 °C. The research results can provide theoretical methods and technical support for the optimization of heat storage performance of tunnel surrounding rock.

Abstract:A novel methodology is established for the reasonable seismic function evaluation of urban water supply network from the perspectives of supplying water for daily living and firefighting. First， based on the seismic fragility model of pipelines and the fire risk model of user nodes， the physical seismic damage scenario of water supply network is generated for the target peak ground acceleration. Next， the hydraulic model is modified according to the physical seismic damage scenario of water supply network while the hydraulic adjustment of water flow in the water supply network is performed based on the pressure-dependent demand model. Afterwards， the function of water supply network for post-earthquake daily living and firefighting is evaluated， and the influence of firefighting water demand on daily living water demand is discussed. Finally， the relationship between serviceability indexes and reliability indexes at different peak ground acceleration is revealed. The numerical results show that at the same peak ground acceleration， the evaluation values based on serviceability indexes are greater than those based on reliability indexes. Under the action of small peak ground acceleration （0.2 g and 0.25 g）， both daily living and firefighting water demand can be met at the same time， and firefighting water demand has little effect on daily living water demand. Under the action of large peak ground acceleration （0.40 g and 0.45 g）， due to the serious damage of the water supply network， both daily living and firefighting water demand can not be well satisfied， and firefighting water demand has little impact on daily living water demand. Under the action of medium peak ground acceleration （0.30 g and 0.35 g）， firefighting water demand has a great influence on daily living water demand， about 7 %.

Abstract:To enhance the accuracy of virtual wayfinding experiments widely used in the study of wayfinding efficiency in airport terminals， this paper conducted a virtual controlled experiment involving 13 712 participants divided into five groups to investigate the influence of stochastic-trajectory-driven mechanism， true-trajectory-driven mechanism， and their combined application on the experimental outcomes. The findings reveal that， significant differences in decision-making time between the no-avatar environment and those entirely driven by the true-trajectory-driven mechanism， while no significant differences were observed when compared to the fully stochastic-trajectory-driven mechanism. Moreover， as the proportion of the stochastic-trajectory-driven mechanism in both driving mechanisms increased， these differences gradually diminished. Additionally， in terms of the success rate of wayfinding tasks and detour rates， there were no significant differences between the two mechanisms and their different combinations compared to the no-avatar environment. Therefore， the driving mechanisms can influence the accuracy of virtual experiments related to decision time.

Abstract:The frequency and intensity of disastrous storm surges and typhoon events due to global climate change are increasing， leading to heightened requirements for the wind resistance of urban landscape trees. Enhancing the root anchoring force is an important way to improve the wind resistance of tree species.Fourteen tree species in Shanghai were selected to conduct a static tension test， and the anchoring force of different tree species was compared in this paper. Based on the root distribution data of 14 tree species collected by the “complete excavation method”， the correlation analysis and nonlinear regression analysis were performed to explore the correlation between root architecture and anchoring force. The preliminary results indicate that the sequence of the anchoring forces of the 14 root systems is as follows： Cyclobalanopsis gracilis > Nyssa aquatic > Acer buergerianum > Acer buergerianum > Cinnamomum japonicum > Liquidambar styraciflua > Liquidambar formosana > Cotinus coggygria >Pyrus calleryana > Ligustrum lucidum > Zelkova serrate > Quercus nuttallii > Triadica sebifera > Tilia miqueliana > Taxodiomera peizhongii； The correlation analysis screened out 11 indexes significantly correlated with root anchorage force， all of which were positively correlated. The P values of the 11 indexes are in a descending order of R₁₅₀₀，R₁₀₀₀，R₅₀₀，M_r，N_h，N_o，S_r，R_h，R_o，N_d，and D_g. It is found that indexes describing the horizontal characteristics of roots have a greater influence on the anchorage force of roots than indexes describing the vertical growth of roots. The multiple linear regression model of M_r， N_h， R_500， and F_max is obtained by multiple stepwise regression analysis F_max=－3.620+0.699M_r+0.589N_h+0.356R₅₀₀. In conclusion， this study obtained the anchoring force ranking of tree roots and found that the horizontal projection index of roots and root weight had significant effects on the anchoring force. The results enriched the wind-resistant evaluation database of landscape tree species in East China and provided theoretical support for the selection， management， and maintenance of wind-resistant landscape trees.

Abstract:Aiming at the fact that the existing airport pavement evaluation methods are not fully applicable to automated detection technology， this paper analyzes the characteristics of current airport pavement automated detection and reclassifies the types of cement concrete pavement diseases. Based on pavement damage data from 32 airports in China， the deduction values for various diseases in the current pavement evaluation specifications are weighted and combined to obtain the deduction values for new disease types. On this basis， the evaluation indicators for the apparent damage， hidden disease， and comprehensive damage condition of airport cement concrete pavement are developed. By comparing and analyzing the measured values of PCI (pavement condition index) and the distribution characteristics of the index values， the grade thresholds of each index were determined. The comparison of the results of manual and automatic detection and evaluation of pavement damage in Xilinhot airport runway block shows that the safety grade obtained by the newly developed cement concrete pavement damage condition evaluation method is consistent with the evaluation grade of PCI.

Abstract:Risky driving behaviors are the main cause of road traffic accidents， with a third of accidents caused by distracted driving. Driving distraction recognition is an efficient approach to improve traffic safety. Current methodologies for driving distraction recognition mainly rely on aggregated multi-sensor data， which limits their extensive application to existing vehicles. Therefore， a two-stage method is proposed in this paper based on inertial measurement unit （IMU） data， a widely available data， for driving distraction recognition. In the first stage， a characterization method based on the evolution of probability density distribution is proposed to represent distracted driving behaviors that are closely coupled with operating conditions. In the second stage， the deep forest algorithm is employed to construct a classification model capable of recognizing driving distraction in complex practical scenarios. An empirical experiment is conducted using IMU data from smartphones in online hailing cars in Shanghai to validate the proposed recognition method. The results indicate that： the distraction recognition method proposed is validated， and the longitudinal characteristics represent the distracted driving behaviors. The proposed characteristics， when compared with the traditional ones， significantly enhance the performance of the model with an increase of 20.4 % in accuracy and 10.2 % in precision. The deep forest model reduces false alarms by more than 10 % while maintaining a high recall rate， compared to support vector machine （SVM） and extreme gradient boosting （XGBoost）.

Abstract:This paper addresses energy-efficient driving strategies for autonomous connected vehicles on ecological roads under mixed traffic flow conditions. A wildlife passage scenario， which significantly impacts energy-saving driving， is extracted， and an application framework for wildlife passages within the Internet of Vehicles （IoV） is developed. A driving model for vehicles on ecological roads under the IoV environment is also constructed， utilizing dynamic programming for discretized analysis and state division. An energy-efficient driving model for vehicles within mixed traffic flow is optimized and established. The Q-learning algorithm is applied to optimize and solve the energy-saving driving model for a single vehicle. Based on the ecological roads in Shanghai， a simulation scenario considering the risk of wildlife crossing is created to validate the energy-saving driving strategies in the IoV environment. The results show that the proposed energy-saving strategy can reduce vehicle fuel consumption by 6 % to 11 %. Additionally， the energy-saving effect improves with increasing traffic density of vehicles， verifying both the reasonableness of the model and the effectiveness of the algorithm.

Abstract:To address the problem of serious road damage at stations and intersections during the trial run of virtual rail trains， the vehicle-tire-road interaction is considered， and the dynamic tire forces are obtained by constructing a virtual rail train dynamics model with Abaqus finite element software to develop a tread tire and viscoelastic asphalt pavement model， and the tire-road contact stresses at uniform speed and under braking conditions are analyzed and compared based on the arbitrary Lagrange-Euler（ALE） method. The contact stress characteristics of tire and pavement at uniform speed and under braking conditions are analyzed and compared based on the ALE method， and the effects of slip rate and load on the contact stress of braking conditions were studied. The results show that the longitudinal stress during braking is the main cause of road damage， and the slip rate and load have a significant effect on the contact stress during braking. The maximum longitudinal stress under braking conditions increases by approximately 979 kPa compared to uniform speed conditions. When the slip rate increases from 0.02 to 0.06， the maximum longitudinal stress increases by approximately 99.8 %. When the load increases from 40 kN to 50 kN， the maximum longitudinal stress at the edge of the tire increases by approximately 98.8 %. Therefore， braking should be avoided as much as possible when the train is running， and at the same time the train load should be in a reasonable range.

Abstract:The operation of large track maintenance machinery mainly includes tamping operation and grinding operation， which is an important operation mode to maintain the good geometric state of the line. In order to formulate a reasonable tamping and grinding operation plan and ensure the safe operation of the line， the annual tamping and grinding operation plan preparation model is developed to optimize the average annual geometric irregularity and the field operation capacity as constraints， and the improved enumeration method is used to solve the model. The model has been applied to the Beijing-Shanghai Railway for verification. The results show that the operation plan of large track maintenance machinery developed by the model can improve the improvement rate of track geometric state， reduce the average value of annual geometric irregularities， and provide a reference for the planning of on-site tamping and grinding operations.

Abstract:Estuarine is a highly dynamic place for organic carbon transport and burial， which plays an important role in global carbon cycle. The organic carbon dynamics in coastal wetlands is important for assessing the “source/sink” effect of carbon in coastal ecosystems. This paper focuses on the organic carbon exchange in estuaries. First. it illustrates the vertical burial mechanism of organic carbon in coastal wetlands and its lateral transport process with offshore areas. Then， it summarizes the current methods of organic carbon source tracing and organic carbon flux estimation. Afterwards， it discusses the application of remote sensing technology in the inversion and estimation of organic carbon in estuaries， based on the generalization of field observation instruments and laboratory measurement techniques for determining organic carbon components. Finally， it conducts a comparison of the research of the carbon cycle models of coastal wetland ecosystems. It proposes that future research should focus on improving the applicability and stability of the models， and that the long-term field observations， laboratory techniques， satellite remote sensing monitoring and carbon cycle model simulations should be combined to accurately quantify and predict the carbon sink capacity of estuaries with high-precision simulations.

Abstract:This paper proposed a method to determine background noise of fiber temperature sensing data based on wavelet denoising， and then detected in-sewer inflow events without disturbing sewer flow conveyance. This method proposed was validated using detected dynamic inflow events in an actual sewer system. It was found that different wavelet denoising algorithms provide background noises that span a wide range， and a noise threshold of about ±0.3 ℃ corresponds to the best identification of actual sewer and stormwater inflow events. Threshold rescaling is the dominant factor for algorithm employment， where the multi-level rescaling method is obviously superior to the non-rescaling and single-level rescaling method. Accordingly， optimized parameters for the wavelet denoising algorithm including wavelet function， threshold selection rules and threshold rescaling were proposed， to enhance the reliability of sewer detection.

Abstract:This paper proposes an image preprocessing method for visual simultaneous localization and mapping (SLAM) systems in dynamic environments， which can be easily integrated into existing visual SLAM systems to enable stable， accurate， and continuous operation in highly dynamic environments. First， it proposes a dynamic object recognition algorithm that integrates the use of semantic segmentation networks and optical flow estimation networks to robustly and accurately identify potential dynamic objects in images. Then， to detect shadows associated with dynamic objects， it proposes a shadow recognition algorithm based on region growing. Afterwards， it uses image completion techniques to fill in the gaps left by the removal of dynamic objects from the images. Finally， it combines this image preprocessing method with stereo ORB-SLAM2 and conducts experiments on the KITTI dataset， which demonstrates that the proposed image preprocessing method significantly improves the positioning accuracy of visual SLAM systems. Each module in the image preprocessing method plays an irreplaceable role.

Abstract:To address the decline of lifespan and overall performance caused by frequent maneuver in traditional constellation maintenance， this paper proposes an autonomous relative structure maintenance method using atmosphere drag. First， it clarifies the relationship between atmosphere drag and orbital phase of low earth orbit(LEO) satellite by theoretical analysis. Next， considering the constraint of satellite power and attitude control， It designs a method by rotating solar panel to change effective frontal area of the satellite so as to achieve autonomous structure maintenance of LEO constellation. Finally， it conducts a simulation and validates that by changing frontal area of solar panel， the relative phase deviation of two satellites is maintained within 0.1 degree. The relative semi-axis deviation is controlled within 40 meters. Active station-keeping control is not needed in one year， and this method saves at least 13.284 kg of fuel consumption in entire lifespan of satellite. Therefore， the continuity of satellite services is ensured and lifetime of satellite is prolonged.

Abstract:This paper analyzed the situation and course of the Russian-Ukrainian conflict based on time-series night-time light remote sensing data， and further investigated the economic impact of the Russian-Ukrainian conflict in relation to the spatial and temporal variations in gross domestic product（GDP）. There was a significant reduction in light intensity at the beginning of the conflict and a recovery in light intensity at a later stage， with the timing of the light changes being consistent with major events in the conflict. The capital city and Russian-occupied areas did not show a significant decrease in light during the conflict， whereas the states where conflict occurs were more frequently significantly affected. Light distributions showed significant positive correlations throughout the conflict. However， there were differences in clustering distributions and hot and cold spot locations at different stages of the conflict. The spatial distribution of GDP shows that the Russia-Ukraine conflict has caused a sharp economic decline in other regions except the capital， port cities and Russian-occupied areas. Areas with heavy light losses were more consistent with the main crop production areas in Ukraine， which will lead to a decrease in crop yields and thus affect the economy.