作者机构：
[Xu, Linrong; Li, Yongwei; Shang, Yonghui; Xu, LR] Cent South Univ, Sch Civil Engn, Changsha 410075, Peoples R China.;[Xu, Linrong; Li, Yongwei; Xu, LR] Cent South Univ, Natl Engn Res Ctr High Speed Railway Construct Te, Changsha 410075, Peoples R China.;[Chen, Shuyang] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.
通讯机构：
[Xu, LR ] C;Cent South Univ, Sch Civil Engn, Changsha 410075, Peoples R China.;Cent South Univ, Natl Engn Res Ctr High Speed Railway Construct Te, Changsha 410075, Peoples R China.
关键词：
machine learning;earthquakes;debris flow susceptibility;convolutional neural network;deep neural network;watershed unit
摘要：
Jiuzhaigou is situated on a mountain-canyon region and is famous for frequent tectonic activities. An abundance of loose co-seismic landslides and collapses were produced on gullies after the Jiuzhaigou Earthquake on August 8, 2017, which was served as material source for debris flow in later years. Debris flow appears frequently which are seriously endangering the safety of people's lives and properties. Even the earliest debris flow appeared in areas where no case ever reported before. The debris flow susceptibility evaluation (DFSE) is used for predicting the areas prone to debris flow, which is urgently required to avoid hazards and help to guide the strategy of preventive measures. Therefore, this work employs debris flow in Jiuzhaigou to reveal the characteristics of disaster-pregnant environment and to explore the application of machine learning in DFSE. Some new viewpoints are suggested: (i) Material density factor of debris flow is first adopted in this work, and it is proved to be a critical factor for triggering debris flows by sensitivity analysis method. (ii) Deep neural network and convolutional neural network (CNN) achieve relatively good area under the curve (AUC) values and are 0.021-0.024 higher than traditional machine learning methods. (iii) Watershed units combined with CNN-based model can achieve more accurate, reliable and practical susceptibility map. This work provides an idea for prevention of debris flow in mountainous lands.
摘要：
Sialic acid (SA) is a kind of functional monosaccharide which exists widely in edible bird's nest (EBN), milk, meat, mucous membrane surface, etc. SA is an important functional component in promoting brain development, anti-oxidation, anti-inflammation, anti-virus, anti-tumor and immune regulation. The intestinal mucosa covers the microbial community that has a significant impact on health. In the gut, SA can also regulate gut microbiota and metabolites, participating in different biological functions. The structure, source and physiological functions of SA were reviewed in this paper. The biological functions of SA through regulating key signaling pathways and target genes were discussed. In summary, SA can modulate gut microbiota and metabolites, which affect gene expressions and exert its biological activities. It is helpful to provide scientific reference for the further investigation of SA in the functional foods.
期刊：
Journal of Energy Storage,2024年78:109965 ISSN：2352-152X
通讯作者：
Mei, SJ
作者机构：
[Mei, Shuo-Jun] Sun Yat Sen Univ, Sch Atmospher Sci, Zhuhai, Peoples R China.;[Hu, Jiang-Tao] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha, Hunan, Peoples R China.;[Mei, Shuo-Jun; Mei, SJ] Sun Yat Sen Univ, Haiqin Bldg 2, Zhuhai 519082, Guangdong, Peoples R China.
通讯机构：
[Mei, SJ ] S;Sun Yat Sen Univ, Haiqin Bldg 2, Zhuhai 519082, Guangdong, Peoples R China.
关键词：
Salt gradient solar pond;Stability analysis;Thermosolutal convection simulation;Porous layer;Thermal energy storage
摘要：
The salt gradient solar pond (SGSP) can capture and store a large amount of solar energy for a long time, making it an efficient and economical solar energy facility. The long-term operational stability of SGSP can be damaged by interface erosion, which is caused by thermosolutal convection. Attaching porous layers is a promising approach to slow down interface erosion. In this study, we simulated the unsteady thermosolutal convection in SGSP with Lattice Boltzmann methods (LBM). The effects of a porous layer on salinity gradient stability are analyzed with boundary equilibrium and marginal criterion. The simulation results show that the SGSP becomes thermally unstable when the interface erosion begins. By attaching a porous layer to the bottom surface, the convective flow is weakened and the instability in SGSP is reduced. The stability analysis shows that the thermally unstable state in SGSP transits into a theoretically stable state by attaching a porous layer. As the stable state is prolonged, the fluid temperature in the storage layer increases. We also find that reducing the permeability of the porous layer or increasing the layer thickness prolongs the stable state. This study helps to improve future SGSP design and promote its engineering application.
摘要：
Conventional grouting materials often exhibit shortcomings when faced with water rushing in karst strata, such as easy dispersion, poor stability, and uncontrollable diffusion. This study introduces an organic-inorganic hybrid water-swelling material for grouting based on excellent synergistic interactions among Polymethylene Polyphenyl Isocyanate (PAPI), Nitrogen tetroxide (N204), Portland cement, and Triethylenediamine (A33) using a straightforward process. Meanwhile, optimal formulations for the WSGM are determined using a proposed matrix analysis model. Under specific conditions with an alcohol ester ratio of 0.9, cement content of 50 %, and catalyst content of 50 %, the resulting water-swelling grouting material (WSGM) exhibits a three-dimensional network structure, high viscosity, exceptional stability, and robust scour resistance (with an initial expansion time of 11 s, a gel time of 91 s, a volume expansion rate of 600 %, a compressive strength of 0.62 MPa, and a bonding strength of 0.39 MPa). The excellent performance of the WSGM is validated through a series of experimental tests. The potential formation mechanisms were discussed, considering the hardening process, Xray diffraction (XRD) analysis, and scanning electron microscopy (SEM) analysis. This research holds the potential to advance the development of organic-inorganic hybrid water-swelling materials with excellent performance, opening new avenues in material preparation.
期刊：
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing,2024年17:4859-4874 ISSN：1939-1404
通讯作者：
Hu, J
作者机构：
[Hu, Jun; Zheng, Wanji; Wu, Wenqing; Zhang, Xing; Liu, Jihong; Liu, Xiaoge] Cent South Univ, Sch Geosci & Info Phys, Changsha 410083, Peoples R China.;[Jin, Xibo] Wuhan Univ, Sch Geodesy & Geomat, Wuhan 430079, Peoples R China.;[Duan, Meng] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410081, Peoples R China.
通讯机构：
[Hu, J ] C;Cent South Univ, Sch Geosci & Info Phys, Changsha 410083, Peoples R China.
关键词：
InSAR;subsurface fluid activity;three-dimensional (3-D) displacements;volumetric strain model
摘要：
Monitoring the actual surface deformation caused by subsurface fluid activities is crucial for comprehending the subsurface fluid mutation process. Incorporation of InSAR observations in a prior volume strain model can facilitate the estimation of subsurface fluid volumetric changes and three-dimensional (3-D) surface deformation. However, the model parameters, i.e., the thickness and depth of the subsurface fluid reservoir, are assumed to be known a priori. Therefore, it is impossible to acquire the precise model parameters in practice. Therefore, we proposed a novel approach for adaptive estimation of the model parameters by utilizing the black hole strategy method integrated with the particle swarm optimization algorithm. First, the performance of this method was tested through simulation experiments. The results suggest that the proposed method can precisely determine the model parameters and 3-D deformations of the subsurface fluids. Finally, the proposed model was tested using actual data from the Shale gas area in Texas and the Kilauea Caldera volcano in Hawaii, USA. For long-term, slow small deformations or sudden large deformations caused by the subsurface fluids, the proposed algorithm can obtain corresponding 3-D deformations, especially in the presence of incoherent regions, which can still obtain a complete 3-D deformation field.
摘要：
An advanced synthetic aperture radar interferometry (InSAR)-based iterative tropospheric decomposition model for more effectively mitigating both vertically stratified and turbulent delays is proposed in this article. The novelty of the model lies in two aspects: 1) incorporating turbulence variance, which characterizes the statistical properties of atmospheric turbulence, into a stochastic model when iteratively removing stratified delay and 2) taking the distance and turbulence variance as the weight factors of samples, simultaneously, in spatially interpolating turbulence. In addition, our model is implemented interferogram by interferogram, so we do not need time-series InSAR datasets. The effectiveness of the proposed method is tested and validated using a set of simulated experiments and an in-site experiment over Hawaii Island, and the experimental results show that our method can mitigate tropospheric delays efficiently and robustly.
作者机构：
[Chen, Ying; Liu, Peng; Huang, Jingxiang; Cheng, Xiang; Liu, Lei; Zhang, Sanling; Yu, Zhiwu] Cent South Univ, Sch Civil Engn, 22 Shaoshan Rd, Changsha 410075, Peoples R China.;[Liu, Peng; Yu, Zhiwu] Natl Engn Res Ctr High Speed Railway Construct, Changsha 410075, Peoples R China.;[Liu, Peng; Yu, Zhiwu] China Railway Grp Ltd, 69 Fuxing Rd, Beijing 100039, Peoples R China.;[Chen, Lei; Liu, Peng] China Railway 10 Engn Grp Co Ltd, 2000 Shunhua Rd, Jinan 250101, Peoples R China.;[Liu, Lei] Yili Normal Univ, Sch Phys & Technol, 448 Jiefang West Rd, Yining 835000, Peoples R China.
通讯机构：
[Liu, P ] C;Cent South Univ, Sch Civil Engn, 22 Shaoshan Rd, Changsha 410075, Peoples R China.;Natl Engn Res Ctr High Speed Railway Construct, Changsha 410075, Peoples R China.;China Railway Grp Ltd, 69 Fuxing Rd, Beijing 100039, Peoples R China.;China Railway 10 Engn Grp Co Ltd, 2000 Shunhua Rd, Jinan 250101, Peoples R China.
关键词：
super-long mass concrete;temperature field;strain;thermal stress;shrinkage-compensating concrete;numerical simulation
摘要：
In this study, the combination of ordinary cement concrete (OCC) and shrinkage-compensating concrete (SCC) was utilized to pour super-long mass concrete. The temperature and strain of the concrete were continuously monitored and managed actively after pouring. The investigation focused on the temporal and spatial distribution patterns of the temperature field, the temperature difference between the core and surface, and the strain evolution. Based on the constructed hydration exothermic model of layered poured concrete, the effects of the SCC, molding temperature, and surface heat transfer coefficient on the temperature field were analyzed. The results show that the temperature of super-long mass concrete rises quickly but falls slowly. SCC exhibits higher total hydration heat than OCC. The temperature field is symmetric along the length but asymmetric along the thickness due to varying efficiency of heat dissipation between the upper and lower parts of the concrete. After final setting of the concrete, the strain varies opposite to the temperature and peaks at -278 mu epsilon. A few short cracks are observed on the end of the upper surface. Moreover, the numerical simulation results are in good agreement with the measured results. Increasing the molding temperature and surface wind speed increases the temperature difference between the core and surface. Conversely, increasing the thickness of the insulation layer is an effective way to curtail this difference. Thermal stress analysis is carried out and shows that lowering the molding temperature of SCC and increasing the thickness of insulation material can effectively reduce thermal stress.
摘要：
The salt gradient solar pond (SGSP) is a low-cost and large-scale solar energy capture and storage device. The stability of the non-convective zone (NCZ) is critical for the well-functioning and efficiency of SGSP. To understand when and how SGSP lost its effectiveness, the turbulent double-diffusive convection in solar ponds was first solved numerically with a Large Eddy Simulations (LES) model. The simulations show that attaching a porous layer or increasing the initial salt concentration effectively delays the destruction of NCZ. By increasing the initial salt concentration from 5.2% to 20.8%, the destruction time increases from 7 to 22 h. By attaching a porous layer, the overturn time can increase by about 8 h, resulting in a temperature rise from 46 C-o to 73 C-o in the storage layer. The flow field analysis shows that both interface erosion and turbulent mixing in NCZ cause the destruction of NCZ. The stability analysis shows that the turbulent mixing decreases the salinity gradient in NCZ, making it more susceptible to erosion. By inhibiting the turbulent mixing, the porous layer at the bottom can effectively delay the arrival of NCZ destruction. Thus, the heat storage capacity and stability of solar ponds are enhanced.
摘要：
Thermal cracking is one of the most annoying distresses in asphalt pavements. The cracking of asphalt pavements caused by extremely low temperature and the damage of thermal fatigue caused by repeated temperature var-iations are particularly pronounced. The service condition of asphalt pavements has been affected significantly. Laboratory experiments with cyclic loads simulating the actions caused by repeated temperature variations on pavements have been conducted in many previous studies to investigate the thermal fatigue characteristics of asphalt mixtures. In those studies, an equivalent cyclic mechanical stress that can be applied by an actuator was mostly used to replace the cyclic thermal stress induced by a temperature variation. It could simplify the experimental process but could not consider the performances of asphalt mixtures varying as a function of temperature. In the present study, the thermal fatigue properties and cracking behaviors of asphalt mixtures were comprehensively investigated through a modified thermal stress restrained specimen test (TSRST) and the nu-merical analysis. Various temperature ranges (-20 to-10 degrees C,-10 to 0 degrees C), cyclic cooling rates (10 degrees C/h, 20 degrees C/ h), low-temperature performance cooling rates (10 degrees C/h, 8 degrees C/h, 6 degrees C/h, 4 degrees C/h, 2 degrees C/h) and pre-crack di-mensions were considered for the study to address the influences of those parameters on the analysis results. Based on the testing and simulation results, it was found that the effects of thermal fatigue on asphalt mixtures under different temperature variations and cooling rates were quantified, and the damage characteristics of the asphalt mixtures were also explored. The results showed that under the low-temperature performance state, the thermal stress of asphalt mixtures increases with a uniform cooling rate and it could be obtained that the faster the cooling rate, the larger the thermal stress generated. In the cyclic thermal stress test, due to the viscoelastic properties of asphalt mixtures, the thermal stress showed significant stress relaxation phenomena under the temperature variations. The magnitude of thermal stress decreased gradually within each cycle. It demonstrates that under the same temperature variation, the thermal stress decreases continuously with the increasing thermal cycles. Through the numerical simulation, it was clear that under different temperature ranges and cooling rates, the magnitude of thermal stress increased with the temperature range decreased, whereas the magnitude of thermal stress increased with an acceleration of the cooling rate. The lower temperature range induced a larger stress intensity factor (KI), which implies a faster cracking evolution. Analyzing the effects of different pre-crack dimensions on the number of temperature cycles, the height of pre-crack showed significant effects on the number of temperature cycles than width.
期刊：
International Journal of Pavement Research and Technology,2023年:1-14 ISSN：1996-6814
通讯作者：
Kefei Liu<&wdkj&>Kang Jiang
作者机构：
[Jiatuo Wei; Kefei Liu] School of Civil Engineering, Central South University of Forestry & Technology, Changsha, People’s Republic of China;Hunan Provincial Engineering Research Center for Construction Solid Wastes Recycling, Changsha, People’s Republic of China;[Kang Jiang] Hunan Communications Research Institute Co. LTD, Changsha, People’s Republic of China;[Quan Li] School of Civil Engineering, Central South University of Forestry & Technology, Changsha, People’s Republic of China<&wdkj&>Hunan Provincial Engineering Research Center for Construction Solid Wastes Recycling, Changsha, People’s Republic of China
通讯机构：
[Kefei Liu] S;[Kang Jiang] H;School of Civil Engineering, Central South University of Forestry & Technology, Changsha, People’s Republic of China<&wdkj&>Hunan Communications Research Institute Co. LTD, Changsha, People’s Republic of China
摘要：
To explore the effect of acid rain corrosion on the cohesion performance of asphalt and its mechanism, graphene oxide (GO) was used to modify epoxy asphalt and 70# base asphalt, TAFPACK Super (TPS) high viscosity asphalt and epoxy asphalt were used as the control group, the periodic dry–wet cycle immersion test was used to simulate the acid rain environment to study the effect of acid rain on the physical properties, composition, cohesion and adhesion between different asphalt binders and aggregates. Furthermore, combined with aging test, the aging resistance of each asphalt after acid corrosion was investigated. The results show that acid rain corrosion can significantly decrease the adhesion between asphalt and aggregates and the cohesion of asphalt itself, resulting in serious moisture damage of asphalt. GO modified epoxy asphalt has better acid rain corrosion resistance than other asphalt. GO improves the cross-linking density between asphalt molecules. The polar groups and low shrinkage thermosetting resin of GO modified epoxy asphalt make it has excellent adhesion and high cohesion, which can effectively resist moisture erosion, peeling and temperature stress cracking, thus effectively resist the corrosion of acid rain. Aging deteriorates the performance of asphalt binder and decreases its acid corrosion resistance. GO modified epoxy asphalt can effectively inhibit the aging of asphalt binder, thus resisting the deterioration caused by aging.
