Hydrocarbon Charging and Adjustment in the Northern Slope of the Bongor Basin, Chad
LI Wei and WEN Zhigang
Understanding the hydrocarbon charge history and accumulation process is crucial to petroleum exploration in the Bongor Basin, Chad. The chronology of hydrocarbon accumulations in the buried-hill of the basin was investigated by using a suite of techniques including organic geochemistry, fluid inclusion, Fourier transform infrared (FT-IR) spectroscopy, apatite fission track analysis (AFTA) and thermal history modeling. The results indicate that in the Bongor Basin, Subzone B and Subzone R-P of the buried-hill belt contain two types of oil inclusions exhibiting yellow-green and blue-green fluorescence, representing different stages of hydrocarbon charging. Based on AFTA and tuff zircon fission track data, it is inferred that different buried-hill zones experienced two phases of primary hydrocarbon accumulation, both peaking during 75-65 million years. In Subzone B, a secondary hydrocarbon accumulation event occurred during the uplift and reworking stage since the Late Cretaceous, characterized by hydrocarbon adjustment and redistribution. Most hydrocarbons are hosted in structural fractures, with the adjustment phase occurring approximately 30 million years ago.Understanding the hydrocarbon charge history and accumulation process is crucial to petroleum exploration in the Bongor Basin, Chad. The chronology of hydrocarbon accumulations in the buried-hill of the basin was investigated by using a suite of techniques including organic geochemistry, fluid inclusion, Fourier transform infrared (FT-IR) spectroscopy, apatite fission track analysis (AFTA) and thermal history modeling. The results indicate that in the Bongor Basin, Subzone B and Subzone R-P of the buried-hill belt contain two types of oil inclusions exhibiting yellow-green and blue-green fluorescence, representing different stages of hydrocarbon charging. Based on AFTA and tuff zircon fission track data, it is inferred that different buried-hill zones experienced two phases of primary hydrocarbon accumulation, both peaking during 75-65 million years. In Subzone B, a secondary hydrocarbon accumulation event occurred during the uplift and reworking stage since the Late Cretaceous, characterized by hydrocarbon adjustment and redistribution. Most hydrocarbons are hosted in structural fractures, with the adjustment phase occurring approximately 30 million years ago.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1124 (2025)
- DOI：10.11908/j.issn.0253-374x.24019
Initial Geolocation Accuracy Monitoring and Improvement of Gaofen-3 Synthetic Aperture Radar Images Over Multiple Terrains
LEI Zhenkun, FENG Yongjiu, XI Mengrong, WANG Jiafeng, and TONG Xiaohua
To monitor and improve the geolocation accuracy of domestic Synthetic Aperture Radar (SAR) payloads, this paper identifies wind turbine locations across three terrain types using high-resolution remote sensing imagery and deep learning models. Leveraging the strong scattering characteristics of wind turbines in SAR imagery, it constructs a large-scale ground control point (GCP) database for long-term and wide-area geometric processing of SAR images. The results show that Gaofen-3 Fine Strip II (FSII) mode imagery exhibits periodic fluctuations in geolocation accuracy from 2017 to 2020, with a cycle of approximately 747.99 days, during which the accuracy gradually degrades from its peak. It also analyzes the influence of terrain on geometric positioning, revealing that mountainous areas experience the lowest positioning accuracy. Using the constructed GCP database, the average geolocation error of Gaofen-3 FSII imagery is reduced from 44.64 meters to 7.94 meters across various terrains, achieving consistent accuracy across all three terrain types.To monitor and improve the geolocation accuracy of domestic Synthetic Aperture Radar (SAR) payloads, this paper identifies wind turbine locations across three terrain types using high-resolution remote sensing imagery and deep learning models. Leveraging the strong scattering characteristics of wind turbines in SAR imagery, it constructs a large-scale ground control point (GCP) database for long-term and wide-area geometric processing of SAR images. The results show that Gaofen-3 Fine Strip II (FSII) mode imagery exhibits periodic fluctuations in geolocation accuracy from 2017 to 2020, with a cycle of approximately 747.99 days, during which the accuracy gradually degrades from its peak. It also analyzes the influence of terrain on geometric positioning, revealing that mountainous areas experience the lowest positioning accuracy. Using the constructed GCP database, the average geolocation error of Gaofen-3 FSII imagery is reduced from 44.64 meters to 7.94 meters across various terrains, achieving consistent accuracy across all three terrain types.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1112 (2025)
- DOI：10.11908/j.issn.0253-374x.24036
Research Progress on Hydrogen Leakage Models
MA Tiancai, JING Xiuhui, CHEN Yimeng, YANG Yanbo, and HUA Qingsong
The basic theoretical models established by domestic and foreign researches on hydrogen leakage are reviewed. The characteristics of hydrogen leakage are described from jet structure, diffusion plume, concentration accumulation, etc., and the latest research results on hydrogen leakage based on numerical simulation are introduced. The buoyancy jet models under slow hydrogen leakage are developed. However, model prediction under under-expanded hydrogen jet conditions presents great challenges. The numerical simulation method is very suitable for studying the diffusion law of hydrogen leakage in complex scenarios, but more experimental data are needed. The hydrogen prediction models based on advanced machine learning technology show great application prospect. In the future, hydrogen leakage models need to be further developed to broaden the applicable scenarios and improve the prediction accuracy.The basic theoretical models established by domestic and foreign researches on hydrogen leakage are reviewed. The characteristics of hydrogen leakage are described from jet structure, diffusion plume, concentration accumulation, etc., and the latest research results on hydrogen leakage based on numerical simulation are introduced. The buoyancy jet models under slow hydrogen leakage are developed. However, model prediction under under-expanded hydrogen jet conditions presents great challenges. The numerical simulation method is very suitable for studying the diffusion law of hydrogen leakage in complex scenarios, but more experimental data are needed. The hydrogen prediction models based on advanced machine learning technology show great application prospect. In the future, hydrogen leakage models need to be further developed to broaden the applicable scenarios and improve the prediction accuracy.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1102 (2025)
- DOI：10.11908/j.issn.0253-374x.23435
Influence and Mechanism of Complexing Agents on Performance of Aluminum Sulfate-Based Alkali-Free Liquid Accelerator
SUN Zhenping, GE Yulong, TIAN Juntao, YANG Haijing, and LI Zhilin
The influence of complexing agents including formic acid, oxalic acid and phosphoric acid on the storage stability of aluminum sulfate-based alkali-free liquid accelerator (LA), the setting time of cement paste and the compressive strength of mortar were studied in the present research. And their mechanism were investigated by analyzing hydration process as well as the phase composition and microscopic morphology of cement paste containing aluminum sulfate-based LA using hydration heat flow calorimetry, X-ray diffraction (XRD), thermogravimetric-derivative thermogravimetric (TG-DTG) analysis and scanning electron microscope (SEM). The results show that three kinds of complexing agents improved the storage stability of aluminum sulfate-based LA, and their effect was in the order of phosphoric acid > formic acid > oxalic acid. At the same aluminum sulfate proportion, with the introduction of three individual complexing agent into aluminum sulfate-based LA, the setting time of cement paste was shortened significantly. Among three complexing agents, their effect on improving the accelerating effect of aluminum sulfate-based LA was in the order of formic acid > oxalic acid > phosphoric acid. Using oxalic acid as complexing agent improved the early strength effect of aluminum sulfate-based LA, while phosphoric acid was beneficial to improving the 28 d compressive strength of mortar. The acid radical ions of complexing agents can form a stable complex with Al3+ in aluminum sulfate-based LA, which can increase the content of Al3+ and the amount of AFt formed in the hydrated system, thus enhance the accelerating and early strength effect of aluminum sulfate-based LA.The influence of complexing agents including formic acid, oxalic acid and phosphoric acid on the storage stability of aluminum sulfate-based alkali-free liquid accelerator (LA), the setting time of cement paste and the compressive strength of mortar were studied in the present research. And their mechanism were investigated by analyzing hydration process as well as the phase composition and microscopic morphology of cement paste containing aluminum sulfate-based LA using hydration heat flow calorimetry, X-ray diffraction (XRD), thermogravimetric-derivative thermogravimetric (TG-DTG) analysis and scanning electron microscope (SEM). The results show that three kinds of complexing agents improved the storage stability of aluminum sulfate-based LA, and their effect was in the order of phosphoric acid > formic acid > oxalic acid. At the same aluminum sulfate proportion, with the introduction of three individual complexing agent into aluminum sulfate-based LA, the setting time of cement paste was shortened significantly. Among three complexing agents, their effect on improving the accelerating effect of aluminum sulfate-based LA was in the order of formic acid > oxalic acid > phosphoric acid. Using oxalic acid as complexing agent improved the early strength effect of aluminum sulfate-based LA, while phosphoric acid was beneficial to improving the 28 d compressive strength of mortar. The acid radical ions of complexing agents can form a stable complex with Al3+ in aluminum sulfate-based LA, which can increase the content of Al3+ and the amount of AFt formed in the hydrated system, thus enhance the accelerating and early strength effect of aluminum sulfate-based LA.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1093 (2025)
- DOI：10.11908/j.issn.0253-374x.24255
Risk Assessment of Farmland Soil Pollution Downstream of Pile Leaching Site Based on Heavy Metal Form Analysis
CHEN Yonggui, WEN Zihao, FU Jun, ZHOU Han, and JIANG Zhaoming
In order to reasonably assess the risk of contaminated sites, the total amount of Cu, Pb, Cd, and As heavy metals in the soil was determined by taking the farmland soil downstream of a copper pile leaching site in Yunnan, China as an example. The occurrence forms of the four heavy metals were determined by improved BCR (Bureau of European Communities Reference) continuous extraction method, and the correlation among the four heavy metals was analyzed. The soil heavy metal pollution and potential risk were evaluated by in-situ accumulation index (Igeo), primary and secondary comparison value (RSP) and the risk assessment coding method (RAC). The results show that the average contents of Cu, Pb, Cd, and As are 39.50, 46.98, 0.16, and 82.67 mg·kg-1. Compared with the background value of heavy metals in Yunnan, the over-standard rates of the four heavy metals are 0%, 83.33%, 33.33%, and 100%, among which the pollution of As required special attention. The results of heavy metal occurrence indicate that Cu, Pb, Cd, and As are mainly in residual form, accounting for 83.14% to 95.62%, suggesting that the four heavy metals exist in stable form in soil. A comparison of the four evaluation methods demonstrates that there are significant differences in evaluation results. The Igeo results show that only As pollution exceeds the standard, while the other three heavy metals are pollution-free. The RSP results show that the four heavy metals are pollution-free to the environment. The RAC results show that Cd has a low risk to the soil environment, while the other three heavy metals had no risk. By comparison, it is found that only the total amount of heavy metals in the soil of the polluted site as an evaluation index would exaggerate the pollution risk to a certain extent, and the analysis should be conducted by combining the total amount of heavy metals and the content of their occurrence forms. Although the total concentration of heavy metal pollutants is relatively high, the content of a bioavailable heavy metal is very low, resulting in a minimal risk of diffusion into the environment. Therefore, the study area is subject to mild heavy metal contamination, with a low level of potential ecological risk.In order to reasonably assess the risk of contaminated sites, the total amount of Cu, Pb, Cd, and As heavy metals in the soil was determined by taking the farmland soil downstream of a copper pile leaching site in Yunnan, China as an example. The occurrence forms of the four heavy metals were determined by improved BCR (Bureau of European Communities Reference) continuous extraction method, and the correlation among the four heavy metals was analyzed. The soil heavy metal pollution and potential risk were evaluated by in-situ accumulation index (Igeo), primary and secondary comparison value (RSP) and the risk assessment coding method (RAC). The results show that the average contents of Cu, Pb, Cd, and As are 39.50, 46.98, 0.16, and 82.67 mg·kg-1. Compared with the background value of heavy metals in Yunnan, the over-standard rates of the four heavy metals are 0%, 83.33%, 33.33%, and 100%, among which the pollution of As required special attention. The results of heavy metal occurrence indicate that Cu, Pb, Cd, and As are mainly in residual form, accounting for 83.14% to 95.62%, suggesting that the four heavy metals exist in stable form in soil. A comparison of the four evaluation methods demonstrates that there are significant differences in evaluation results. The Igeo results show that only As pollution exceeds the standard, while the other three heavy metals are pollution-free. The RSP results show that the four heavy metals are pollution-free to the environment. The RAC results show that Cd has a low risk to the soil environment, while the other three heavy metals had no risk. By comparison, it is found that only the total amount of heavy metals in the soil of the polluted site as an evaluation index would exaggerate the pollution risk to a certain extent, and the analysis should be conducted by combining the total amount of heavy metals and the content of their occurrence forms. Although the total concentration of heavy metal pollutants is relatively high, the content of a bioavailable heavy metal is very low, resulting in a minimal risk of diffusion into the environment. Therefore, the study area is subject to mild heavy metal contamination, with a low level of potential ecological risk.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1084 (2025)
- DOI：10.11908/j.issn.0253-374x.23436
Analysis of Influencing Factors and Severity of Chain Rear-End Collision Using Text Mining
WANG Ling, LI Yidan, WANG Zijian, ZHANG Long, XING Yingying, and MA Wanjing
Based on nearly eight years of data collected from Weibo, eight topics related to chain rear-end collisions were identified using the latent Dirichlet allocation (LDA) topic model and social network analysis, revealing the main characteristics and mechanisms of these accidents. The study finds that highways are the primary accident scenes. Accident frequency during rain and snow is higher than in foggy conditions. Failure to maintain a safe following distance and speeding significantly increase accident risk. By assigning topics to each document using LDA and extracting severity information through regular expressions, an ordered logit regression model was constructed to analyze the impact of different topics on accident severity. The results show that the average number of injuries and fatalities in chain rear-end collisions are 2.12 and 1.85 times higher the averages for general motor vehicle traffic accidents, respectively. The severity of chain rear-end collisions on highways is higher than at intersections, with an odds ratio (OR) 3.3 times that of intersections. The OR for foggy-related accidents is 9.4 times that of rainy and snow, while the OR for accidents involving trucks is 4.6 times that of cars is 2.2 times that of buses.Based on nearly eight years of data collected from Weibo, eight topics related to chain rear-end collisions were identified using the latent Dirichlet allocation (LDA) topic model and social network analysis, revealing the main characteristics and mechanisms of these accidents. The study finds that highways are the primary accident scenes. Accident frequency during rain and snow is higher than in foggy conditions. Failure to maintain a safe following distance and speeding significantly increase accident risk. By assigning topics to each document using LDA and extracting severity information through regular expressions, an ordered logit regression model was constructed to analyze the impact of different topics on accident severity. The results show that the average number of injuries and fatalities in chain rear-end collisions are 2.12 and 1.85 times higher the averages for general motor vehicle traffic accidents, respectively. The severity of chain rear-end collisions on highways is higher than at intersections, with an odds ratio (OR) 3.3 times that of intersections. The OR for foggy-related accidents is 9.4 times that of rainy and snow, while the OR for accidents involving trucks is 4.6 times that of cars is 2.2 times that of buses.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1074 (2025)
- DOI：10.11908/j.issn.0253-374x.24213
Identification and Optimization Strategies of Mismatched Region of Public Transport Resource Allocation
WU Jiaorong and TIAN Zili
The mismatch between supply and demand in public transport resource allocation leads to inefficiencies in operations and waste of resources. Therefore, it is essential to identify mismatched regions in public transport resource allocation. However, due to the scale effect of public transport resource allocation and the differences in mobility and travel preferences among regions, it is challenging to identify the mismatch relationship. By calculating the locational quotient (LQ) to identify regions of imbalance between supply and demand, and using the multi-scale geographically weighted regression (MGWR) model to analyze the supply and demand adjustment mechanism with spatial differentiation, this paper comprehensively identified the mismatched regions of public transport resource, and conducted an empirical analysis in Jiading District, Shanghai. The regression results show that the residential-job density, bus service frequency, factory land ratio, and metro station presence have significant local effects on ridership, indicating strong spatial heterogeneity. Based on the induced ridership potential of residential-job density and the bus service frequency, this paper classified the region into four categories: “strong-strong”, “strong-weak”, “weak-strong” and “weak-weak”. Then it proposed differentiated strategies for public transport development. The “strong-strong” and “weak-weak” types represent regions with mismatched supply and demand, where it is recommended to adjust public transport supply using LQ analysis. For the “strong-weak” and “weak-strong” types, strategies should focus on optimization of the network layout and introduction of travel demand, respectively. The proposed method for identifying mismatched public transport resource regions contributes to the theoretical advancement of scientifically allocating public transport resources and improving efficiency while reducing costs.The mismatch between supply and demand in public transport resource allocation leads to inefficiencies in operations and waste of resources. Therefore, it is essential to identify mismatched regions in public transport resource allocation. However, due to the scale effect of public transport resource allocation and the differences in mobility and travel preferences among regions, it is challenging to identify the mismatch relationship. By calculating the locational quotient (LQ) to identify regions of imbalance between supply and demand, and using the multi-scale geographically weighted regression (MGWR) model to analyze the supply and demand adjustment mechanism with spatial differentiation, this paper comprehensively identified the mismatched regions of public transport resource, and conducted an empirical analysis in Jiading District, Shanghai. The regression results show that the residential-job density, bus service frequency, factory land ratio, and metro station presence have significant local effects on ridership, indicating strong spatial heterogeneity. Based on the induced ridership potential of residential-job density and the bus service frequency, this paper classified the region into four categories: “strong-strong”, “strong-weak”, “weak-strong” and “weak-weak”. Then it proposed differentiated strategies for public transport development. The “strong-strong” and “weak-weak” types represent regions with mismatched supply and demand, where it is recommended to adjust public transport supply using LQ analysis. For the “strong-weak” and “weak-strong” types, strategies should focus on optimization of the network layout and introduction of travel demand, respectively. The proposed method for identifying mismatched public transport resource regions contributes to the theoretical advancement of scientifically allocating public transport resources and improving efficiency while reducing costs.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1063 (2025)
- DOI：10.11908/j.issn.0253-374x.23465
Development of a Car-Following Model for Urban Underground Roads Based on Theory-Data Dual-Driving
YANG Hemeng, ZHANG Lanfang, WU Yating, ZHOU Ruida, and LI Xiang
Based on the vehicle trajectory data of urban underground roads in Shanghai, this paper proposes a theory-data driven vehicle car-following model in urban underground roads. The vehicle trajectory data are collected and processed by millimeter wave radar to screen the car-following behavior. Based on the characteristics of car-following behavior on underground roads, a theory-driven intelligent driver model (IDM) and a data-driven long short-term memory (LSTM) car-following model are developed for acceleration, velocity, and distance headway, and error comparison is conducted. Finally, the prediction results of the two types of models are regarded as two sets of observations for the same system state obtained by different observation methods, and the real driving state is predicted by the adaptive Kalman filter method. The IDM-LSTM hybrid model based on speed prediction is developed, achieving a root mean square error of 0.118 7, outperforms the single IDM (0.583 6) and LSTM (0.123 9) models. This paper can provide valuable reference for the operation and road safety management of urban underground roads.Based on the vehicle trajectory data of urban underground roads in Shanghai, this paper proposes a theory-data driven vehicle car-following model in urban underground roads. The vehicle trajectory data are collected and processed by millimeter wave radar to screen the car-following behavior. Based on the characteristics of car-following behavior on underground roads, a theory-driven intelligent driver model (IDM) and a data-driven long short-term memory (LSTM) car-following model are developed for acceleration, velocity, and distance headway, and error comparison is conducted. Finally, the prediction results of the two types of models are regarded as two sets of observations for the same system state obtained by different observation methods, and the real driving state is predicted by the adaptive Kalman filter method. The IDM-LSTM hybrid model based on speed prediction is developed, achieving a root mean square error of 0.118 7, outperforms the single IDM (0.583 6) and LSTM (0.123 9) models. This paper can provide valuable reference for the operation and road safety management of urban underground roads.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1055 (2025)
- DOI：10.11908/j.issn.0253-374x.24023
Multi-Source Data Integration and Application of Airport Smart Runway System
LING Jianming, HOU Tianxin, LIU Shifu, TAO Zefeng, and LI Peilin
Based on the existing concept and architecture of the smart runway, this paper addresses the challenge of managing the smart runway data flow. A systematic analysis of the data characteristics reveals that the data are massive, multi-source, heterogeneous, and multi-frequency. Based on this analysis, it proposes a multi-level data integration framework, a multi-platform physical structure, and a comprehensive data flow architecture for the smart runway. To support efficient and reliable data utilization, as well as classified and long-term data preservation, it develops detailed methods for data preprocessing and standardization. Additionally, it examines the characteristics of smart runway data storage, leading to the design of a corresponding multi-level storage architecture and appropriate storage strategies. The implementation of the proposed system at Rikaze Dingri Airport shows a reduction of over 95% in invalid data without any loss of effective information, achieving unified management and multi-source data sharing. This paper supports the enhanced capabilities of the smart runway, including real-time performance evaluation, advanced risk warning, and intelligent maintenance decision-making.Based on the existing concept and architecture of the smart runway, this paper addresses the challenge of managing the smart runway data flow. A systematic analysis of the data characteristics reveals that the data are massive, multi-source, heterogeneous, and multi-frequency. Based on this analysis, it proposes a multi-level data integration framework, a multi-platform physical structure, and a comprehensive data flow architecture for the smart runway. To support efficient and reliable data utilization, as well as classified and long-term data preservation, it develops detailed methods for data preprocessing and standardization. Additionally, it examines the characteristics of smart runway data storage, leading to the design of a corresponding multi-level storage architecture and appropriate storage strategies. The implementation of the proposed system at Rikaze Dingri Airport shows a reduction of over 95% in invalid data without any loss of effective information, achieving unified management and multi-source data sharing. This paper supports the enhanced capabilities of the smart runway, including real-time performance evaluation, advanced risk warning, and intelligent maintenance decision-making.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1047 (2025)
- DOI：10.11908/j.issn.0253-374x.23434
Effects of Strengthening Methods on Seismic Performance of Reinforced Concrete Columns
HOU Lijun, SUN Wei, XIA Fuzheng, PENG Yuhao, and CHEN Da
An experimental study was conducted on reinforced concrete (RC) columns strengthened using three methods, carbon fiber reinforced polymer (CFRP) jacketing, textile reinforced mortar (TRM) jacketing, and textile reinforced ultra-high toughness cementitious composite (UHTCC) jacketing, under horizontal cyclic loading at different shear span ratios. The study investigated the failure mechanisms and seismic strengthening effects of these strengthening methods. The experimental results reveal that TRU- and TRM- jacketed columns show vertical main cracks at the corners and bending main cracks at the column base, with the TRU jacketing demonstrating better overall integrity than the TRM jacketing. At lower shear span ratios, diagonal cracks in TRU jacketing were significantly less severe than those in TRM ones. In contrast, the CFRP jacketed columns show bending cracks in the plastic hinge region when the shear span ratio exceeded 2.58. While all three strengthening methods provided only modest improvements, they significantly enhanced horizontal deformation capacity and ductility, by up to 100%, and improved energy dissipation capacity by 1.7 to 4.0 times. Among the three strengthening methods, the enhancement in deformation and energy dissipation capacities follow the order of CFRP>TRU> TRM.An experimental study was conducted on reinforced concrete (RC) columns strengthened using three methods, carbon fiber reinforced polymer (CFRP) jacketing, textile reinforced mortar (TRM) jacketing, and textile reinforced ultra-high toughness cementitious composite (UHTCC) jacketing, under horizontal cyclic loading at different shear span ratios. The study investigated the failure mechanisms and seismic strengthening effects of these strengthening methods. The experimental results reveal that TRU- and TRM- jacketed columns show vertical main cracks at the corners and bending main cracks at the column base, with the TRU jacketing demonstrating better overall integrity than the TRM jacketing. At lower shear span ratios, diagonal cracks in TRU jacketing were significantly less severe than those in TRM ones. In contrast, the CFRP jacketed columns show bending cracks in the plastic hinge region when the shear span ratio exceeded 2.58. While all three strengthening methods provided only modest improvements, they significantly enhanced horizontal deformation capacity and ductility, by up to 100%, and improved energy dissipation capacity by 1.7 to 4.0 times. Among the three strengthening methods, the enhancement in deformation and energy dissipation capacities follow the order of CFRP>TRU> TRM.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1035 (2025)
- DOI：10.11908/j.issn.0253-374x.24312
Design Method for Aeroelastic Models of Suspension Bridges Based on Multi-Steel Beam Frame System
LAN Yizhe, GE Yaojun, ZHANG Jinjie, and YANG Yongxin
For long span double-deck suspension bridges with steel truss girder, a new aeroelastic model design method is proposed, referred to as the multi-steel beam frame system (MSBFS), which comprises upper and lower steel beams, horizontal connecting rigid beams, and vertical rigid columns. By transforming the design process into an optimization problem and employing the constrained pattern search method, the design variables for the stiffening beam satisfying the design criteria are obtained. The sensitivity analysis reveals that the modal frequencies are significantly influenced by the dimensions of the horizontal connecting rigid beams, as well as the upper and lower longitudinal steel beams. The dynamic characteristic test results confirm the accuracy of the MSBFS, as the deviation in low-order modal frequencies from the design target values falls within ±5%. As a valuable complement to the full-bridge aeroelastic model design approaches, this design method is well-suited for truss girders, enabling an overall optimal simulation of aerodynamic shape, stiffness and mass system.For long span double-deck suspension bridges with steel truss girder, a new aeroelastic model design method is proposed, referred to as the multi-steel beam frame system (MSBFS), which comprises upper and lower steel beams, horizontal connecting rigid beams, and vertical rigid columns. By transforming the design process into an optimization problem and employing the constrained pattern search method, the design variables for the stiffening beam satisfying the design criteria are obtained. The sensitivity analysis reveals that the modal frequencies are significantly influenced by the dimensions of the horizontal connecting rigid beams, as well as the upper and lower longitudinal steel beams. The dynamic characteristic test results confirm the accuracy of the MSBFS, as the deviation in low-order modal frequencies from the design target values falls within ±5%. As a valuable complement to the full-bridge aeroelastic model design approaches, this design method is well-suited for truss girders, enabling an overall optimal simulation of aerodynamic shape, stiffness and mass system.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1026 (2025)
- DOI：10.11908/j.issn.0253-374x.23413
A Resilience Evaluation Method of Shield Tunnel Structures Considering the Entire Disaster Process
GAN Binlin, ZHANG Dongmei, GAO Junhua, ZHU Meiheng, and HUANG Zhongkai
The connotation of shield tunnel structure resilience was discussed in this paper, based on the adaptive cycling theory and characteristics of structural entire disaster process. Additionally, structural performance evaluation indexes and analysis model were proposed according to structural performance allowances. Moreover resilience grading criteria based on structural performance, restoration cost and affected time were presented. Furthermore, a comprehensive resilience evaluation method for shield tunnel structures of the entire disaster process was proposed, using the analytic hierarchy process and expert confidence index method to establish a comprehensive resilience index evaluation system and determine the weights of indexes. Finally, the reasonableness of this strategy was demonstrated using an engineering field case.The connotation of shield tunnel structure resilience was discussed in this paper, based on the adaptive cycling theory and characteristics of structural entire disaster process. Additionally, structural performance evaluation indexes and analysis model were proposed according to structural performance allowances. Moreover resilience grading criteria based on structural performance, restoration cost and affected time were presented. Furthermore, a comprehensive resilience evaluation method for shield tunnel structures of the entire disaster process was proposed, using the analytic hierarchy process and expert confidence index method to establish a comprehensive resilience index evaluation system and determine the weights of indexes. Finally, the reasonableness of this strategy was demonstrated using an engineering field case.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1016 (2025)
- DOI：10.11908/j.issn.0253-374x.23461
Analysis of Coupling Characteristics of Risk Factors Between Urban Water Supply Networks and Transportation Networks
HU Qunfang, ZHANG Yu, HE Lei, HU Jingqun, WANG Feng, and JI Hongyan
This study investigates the coupling risk factors between urban water supply and transportation networks by analyzing 246 pipe damage incidents (with diameters ≥800 mm) in the central area of Puxi, Shanghai, from 2004 to 2021. It employs an N (network scale) -K (interaction degree) model to construct a risk coupling model for the two networks, revealing the multi-factor risk cascading effects and coupling characteristics of the water supply-transportation coupled network. The findings demonstrate that there exists risk factor coupling between the two networks, with increased coupling corresponding to greater safety risk impacts. The physical attributes of the water supply network itself constitute the primary risk factor affecting its safety. Based on the system decoupling theory, this paper proposes risk control strategies for urban water supply-transportation network coupling, which are of great significance for reducing coupling interactions between the two networks and ensuring their safe operation.This study investigates the coupling risk factors between urban water supply and transportation networks by analyzing 246 pipe damage incidents (with diameters ≥800 mm) in the central area of Puxi, Shanghai, from 2004 to 2021. It employs an N (network scale) -K (interaction degree) model to construct a risk coupling model for the two networks, revealing the multi-factor risk cascading effects and coupling characteristics of the water supply-transportation coupled network. The findings demonstrate that there exists risk factor coupling between the two networks, with increased coupling corresponding to greater safety risk impacts. The physical attributes of the water supply network itself constitute the primary risk factor affecting its safety. Based on the system decoupling theory, this paper proposes risk control strategies for urban water supply-transportation network coupling, which are of great significance for reducing coupling interactions between the two networks and ensuring their safe operation.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1008 (2025)
- DOI：10.11908/j.issn.0253-374x.23418
Propagation Behavior of Concrete Randomness Under Varying Loading Modes
GUO Chenggong and LI Jie
Concrete materials contain intrinsic randomness in their mechanical properties, and this inherent uncertainty shows statistically significant differences under various loading cases. This paper reveals the propagation behavior of concrete randomness under varying loads by combining the relationship between static strength, dynamic strength, and fatigue life from the perspectives of statistical moments and probability density. The findings indicate that the standard deviation of concrete's dynamic strength rises as strain rate increases. The nonlinear relationship between fatigue stress and fatigue life (SN curves) accounts for fatigue life's notable discreteness. First- and second-order statistical moments can accurately reflect the randomness propagation behavior when the relationship between random variables is linear or nearly linear. However, when the relationship between random variables is highly nonlinear, the probability density approach must be adopted.Concrete materials contain intrinsic randomness in their mechanical properties, and this inherent uncertainty shows statistically significant differences under various loading cases. This paper reveals the propagation behavior of concrete randomness under varying loads by combining the relationship between static strength, dynamic strength, and fatigue life from the perspectives of statistical moments and probability density. The findings indicate that the standard deviation of concrete's dynamic strength rises as strain rate increases. The nonlinear relationship between fatigue stress and fatigue life (SN curves) accounts for fatigue life's notable discreteness. First- and second-order statistical moments can accurately reflect the randomness propagation behavior when the relationship between random variables is linear or nearly linear. However, when the relationship between random variables is highly nonlinear, the probability density approach must be adopted.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 1001 (2025)
- DOI：10.11908/j.issn.0253-374x.23394
Two-Scale Stochastic Nonlinear Response Analysis Model for Concrete Structures
LI Jie and CHEN Xin
In this paper, the two-scale random field model is introduced within the framework of the elastic-plastic stochastic damage mechanics for representing the spatial variation of concrete. A framework for stochastic nonlinear response analysis is developed, where the probability density evolution method is adopted to quantify the propagation of randomness in concrete structures, and the two-scale random field model is applied to represent the spatial variation of concrete. The proposed framework is demonstrated by an illustrative example, which address the stochastic nonlinear response of the reinforced concrete frame structure.In this paper, the two-scale random field model is introduced within the framework of the elastic-plastic stochastic damage mechanics for representing the spatial variation of concrete. A framework for stochastic nonlinear response analysis is developed, where the probability density evolution method is adopted to quantify the propagation of randomness in concrete structures, and the two-scale random field model is applied to represent the spatial variation of concrete. The proposed framework is demonstrated by an illustrative example, which address the stochastic nonlinear response of the reinforced concrete frame structure.
- Aug. 26, 2025
- Journal of Tongji University(Natural Science)
- Vol. 53, Issue 7, 993 (2025)
- DOI：10.11908/j.issn.0253-374x.23431
Best Evidence Summary on Exercise Intervention for Women at High Risk of Gestational Diabetes Mellitus
HUANG Cong, SHU Li, JIANG Ruizhe, DU Mengkai, YE Xinxin, and WANG Fang
ObjectiveTo systematically review, evaluate and summarise the best evidence regarding exercise program for women at high risk of gestational diabetes mellitus (GDM) from domestic and international databases, and to provide recommendations for them to prevent GDM.MethodsWith the "6S" evidence model, the two clinical decision support systems of UpToDate and BMJ Best Practice, as well as several international guideline websites, were employed. The search encompassed both Chinese and English databases, including PubMed, Embase, Cochrane Library and CNKI. In addition, six relevant associations were reviewed for the best evidence on exercise in high-risk GDM populations. Evidences were graded using the Australian JBI Evidence Pre-Grading and Evidence Recommendation Levels System, with the strength of recommendations based on the JBI FAME structure and grading principles.ResultsA total of 39 articles were included, comprising 16 guidelines, 17 systematic reviews, 3 expert consensus documents and 3 evidence summaries. Among these, 21 articles (53.8%)were of high quality, and 18 articles (46.2%) moderate. 54 best evidence recommendations were summarized across four domains: medical screening for high-risk GDM populations, exercise risks, exercise prescriptions, and other suggestions/precautions. Of these, 37 recommendations (68.5%) were assigned a recommendation level of 1, one recommendation (1.8%) a level of 2, nine recommendations (16.7%) a level of 4, and seven recommendations(13.0%) a level of 5. Additionally, 50 recommendations (92.6%) were strongly endorsed, while four recommendations (7.4%) were weakly endorsed.ConclusionThe evidence highlights the necessity of pre-exercise assessments for women at high risk of GDM. Regular, moderate-intensity aerobic, resistance, or hybrid exercise during pregnancy−targeting at least 150 minutes per week or 30 minutes per day in at least three sessions per week−was recommended to reduce the risk of GDM and associated pregnancy complications. Additionally, personalized, well-designed, and professionally supervised exercise programs are encouraged to enhance both the safety and adherence.ObjectiveTo systematically review, evaluate and summarise the best evidence regarding exercise program for women at high risk of gestational diabetes mellitus (GDM) from domestic and international databases, and to provide recommendations for them to prevent GDM.MethodsWith the "6S" evidence model, the two clinical decision support systems of UpToDate and BMJ Best Practice, as well as several international guideline websites, were employed. The search encompassed both Chinese and English databases, including PubMed, Embase, Cochrane Library and CNKI. In addition, six relevant associations were reviewed for the best evidence on exercise in high-risk GDM populations. Evidences were graded using the Australian JBI Evidence Pre-Grading and Evidence Recommendation Levels System, with the strength of recommendations based on the JBI FAME structure and grading principles.ResultsA total of 39 articles were included, comprising 16 guidelines, 17 systematic reviews, 3 expert consensus documents and 3 evidence summaries. Among these, 21 articles (53.8%)were of high quality, and 18 articles (46.2%) moderate. 54 best evidence recommendations were summarized across four domains: medical screening for high-risk GDM populations, exercise risks, exercise prescriptions, and other suggestions/precautions. Of these, 37 recommendations (68.5%) were assigned a recommendation level of 1, one recommendation (1.8%) a level of 2, nine recommendations (16.7%) a level of 4, and seven recommendations(13.0%) a level of 5. Additionally, 50 recommendations (92.6%) were strongly endorsed, while four recommendations (7.4%) were weakly endorsed.ConclusionThe evidence highlights the necessity of pre-exercise assessments for women at high risk of GDM. Regular, moderate-intensity aerobic, resistance, or hybrid exercise during pregnancy−targeting at least 150 minutes per week or 30 minutes per day in at least three sessions per week−was recommended to reduce the risk of GDM and associated pregnancy complications. Additionally, personalized, well-designed, and professionally supervised exercise programs are encouraged to enhance both the safety and adherence.
- Aug. 25, 2025
- Journal of Shanghai University of Sport
- Vol. 49, Issue 7, 86 (2025)
- DOI：10.16099/j.sus.2024.10.15.0004
Research Progress on the Interaction Between Rhythmic Molecular Clock and Mitochondrial Quality Control Under the Intervention of Diet and Exercise
ZHANG Zhe, QIAN Shuaiwei and DING Shuzhe
Based on summing up the latest research progress of the interaction between molecular clock and mitochondrial quality under exercise and dietary change, this study proposes that intermittent fasting may promote health by regulating the molecular clock through mitophagy. The interaction between the molecular clock and the mitochondria dynamics can effectively avoid insulin resistance caused by high fat diet. In terms of sports, it has been elucidated that PGC-1, Fis1 and HIF-1 can interact with BMAL1 in adipose tissue, liver and skeletal muscle, respectively, and exercise regulates the interaction of molecular clock and MQC through BMAL1-HIF-1,CLOCK-mitophagy, and AMPK-SIRT1-PGC-1. However, the mechanism of long-term chrono-aerobic/anaerobic exercise and/or different exercise intensities/modes combined with intermittent fasting to regulate the interaction effect of mitochondrial quality and rhythmic molecular clock needs further study. Mitophagy may be the important link in this process. Whether exercise ameliorates metabolic abnormalities induced by high fat diet through the interaction effect of molecular clock and mitochondrial dynamics remains to be explored.Based on summing up the latest research progress of the interaction between molecular clock and mitochondrial quality under exercise and dietary change, this study proposes that intermittent fasting may promote health by regulating the molecular clock through mitophagy. The interaction between the molecular clock and the mitochondria dynamics can effectively avoid insulin resistance caused by high fat diet. In terms of sports, it has been elucidated that PGC-1α, Fis1 and HIF-1α can interact with BMAL1 in adipose tissue, liver and skeletal muscle, respectively, and exercise regulates the interaction of molecular clock and MQC through BMAL1-HIF-1α,CLOCK-mitophagy, and AMPK-SIRT1-PGC-1α. However, the mechanism of long-term chrono-aerobic/anaerobic exercise and/or different exercise intensities/modes combined with intermittent fasting to regulate the interaction effect of mitochondrial quality and rhythmic molecular clock needs further study. Mitophagy may be the important link in this process. Whether exercise ameliorates metabolic abnormalities induced by high fat diet through the interaction effect of molecular clock and mitochondrial dynamics remains to be explored.
- Aug. 25, 2025
- Journal of Shanghai University of Sport
- Vol. 49, Issue 7, 75 (2025)
- DOI：10.16099/j.sus.2023.09.19.0006
Effects of Tai Chi on Motor Function and Primary Motor Cortex in Older Adults:
WANG Minjia, WU Shuya, ZHANG Chun, SHUI Xiaoping, ZHANG Feiyue, HU Hao, and HE Benxiang
ObjectiveThe aim of this study was to investigate the underlying cerebral hemodynamic mechanisms of 12 weeks of Tai Chi exercise to improve motor function in older adults by fNIRS technique.MethodsThirty-four healthy older adults were randomized into a Tai Chi group and a control group. The Tai Chi group received a 12-week Tai Chi intervention, and the control group did not receive any intervention. The subjects' motor functions were assessed before and after the experiment and hemodynamic indices of motor-related brain regions in the walking task state were collected.ResultsIn the within-group comparison before and after the intervention, the results of unipedal stability, Berg scale score and timed rise and walk test in the Tai Chi group were significantly improved compared with the pre-intervention (P<0.05); the oxygenated hemoglobin concentration in the primary motor cortex (M1) and the premotor area-assisted motor area (PMC-SMA) were all significantly increased compared with the pre-intervention (P<0.05). In the post-intervention inter-group comparison, the oxygenated hemoglobin concentrations in the M1 and PMC-SMA brain regions of the Tai Chi group were significantly higher than those of the control group (P<0.05).Conclusion12 weeks of Tai Chi exercise significantly improved the motor function and neural activation of motor-related brain regions in older adults.ObjectiveThe aim of this study was to investigate the underlying cerebral hemodynamic mechanisms of 12 weeks of Tai Chi exercise to improve motor function in older adults by fNIRS technique.MethodsThirty-four healthy older adults were randomized into a Tai Chi group and a control group. The Tai Chi group received a 12-week Tai Chi intervention, and the control group did not receive any intervention. The subjects' motor functions were assessed before and after the experiment and hemodynamic indices of motor-related brain regions in the walking task state were collected.ResultsIn the within-group comparison before and after the intervention, the results of unipedal stability, Berg scale score and timed rise and walk test in the Tai Chi group were significantly improved compared with the pre-intervention (P<0.05); the oxygenated hemoglobin concentration in the primary motor cortex (M1) and the premotor area-assisted motor area (PMC-SMA) were all significantly increased compared with the pre-intervention (P<0.05). In the post-intervention inter-group comparison, the oxygenated hemoglobin concentrations in the M1 and PMC-SMA brain regions of the Tai Chi group were significantly higher than those of the control group (P<0.05).Conclusion12 weeks of Tai Chi exercise significantly improved the motor function and neural activation of motor-related brain regions in older adults.
- Aug. 25, 2025
- Journal of Shanghai University of Sport
- Vol. 49, Issue 7, 63 (2025)
- DOI：10.16099/j.sus.2024.07.19.0004
How to Achieve the Integration and Symbiosis of Sports and Cities?:
WANG Hangying and ZHENG Jiakun
Based on the analysis of the practices of New York, London, Tokyo, Paris and other cities in accelerating the integration of sports and urban development, it is evident that the important ways to promote the integrated development of sports and cities include creating a symbiotic environment to enhance the pace of integration and development of sports and cities, consolidating a symbiotic interface to plan the development situation, focusing on symbiosis and co-prosperity to enhance its vitality, and optimizing the symbiosis mode to unleash its potential. Consequently, to promote the deep integration of sports and cities in China, it is necessary to create a good development environment to stimulate the "new vitality" of sports-city integration, drive the integration and co-governance of multiple bodies to bring together the "new dynamics" of sports-city integration, innovate and expand the symbiotic interface to create a "new carrier" for the integration of sports and cities, explore the model of reciprocity and symbiosis, and open up a "new blue ocean" of the integration.Based on the analysis of the practices of New York, London, Tokyo, Paris and other cities in accelerating the integration of sports and urban development, it is evident that the important ways to promote the integrated development of sports and cities include creating a symbiotic environment to enhance the pace of integration and development of sports and cities, consolidating a symbiotic interface to plan the development situation, focusing on symbiosis and co-prosperity to enhance its vitality, and optimizing the symbiosis mode to unleash its potential. Consequently, to promote the deep integration of sports and cities in China, it is necessary to create a good development environment to stimulate the "new vitality" of sports-city integration, drive the integration and co-governance of multiple bodies to bring together the "new dynamics" of sports-city integration, innovate and expand the symbiotic interface to create a "new carrier" for the integration of sports and cities, explore the model of reciprocity and symbiosis, and open up a "new blue ocean" of the integration.
- Aug. 25, 2025
- Journal of Shanghai University of Sport
- Vol. 49, Issue 7, 53 (2025)
- DOI：10.16099/j.sus.2024.06.19.0003
Tension Between Sports Humanities and Social Sciences: A Dialogue Between Philosophy of Sport and Psychology of Sport
GAO Qiang and Robert SCHINKE
Sports is a concrete human social activity, which is not only related to human psychological activities, but also extends the relevant abstract concepts. Different academic disciplines and scientific theories have shown increasing interest in studying sports, and different disciplinary orientations lead to long-standing disputes. Humanities and social sciences both debate with and inspire each other in the field of sports research. Two scholars, with backgrounds in philosophy and psychology, have engaged in a debate-style dialogue on the creation and use of concepts, the selection of research methods, the highlights of research significance and the exploration of research topics in sport studies. Through dialogue, possibilities and pathways for cross-disciplinary learning within sports humanities have been established, along with how researchers can derive research topics and features from their personal expertise and disciplinary backgrounds.Sports is a concrete human social activity, which is not only related to human psychological activities, but also extends the relevant abstract concepts. Different academic disciplines and scientific theories have shown increasing interest in studying sports, and different disciplinary orientations lead to long-standing disputes. Humanities and social sciences both debate with and inspire each other in the field of sports research. Two scholars, with backgrounds in philosophy and psychology, have engaged in a debate-style dialogue on the creation and use of concepts, the selection of research methods, the highlights of research significance and the exploration of research topics in sport studies. Through dialogue, possibilities and pathways for cross-disciplinary learning within sports humanities have been established, along with how researchers can derive research topics and features from their personal expertise and disciplinary backgrounds.
- Aug. 25, 2025
- Journal of Shanghai University of Sport
- Vol. 49, Issue 7, 44 (2025)
- DOI：10.16099/j.sus.2023.08.02.0001
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