Ocean mining activities have been ongoing for nearly 70 years,making great contributions to industrialization.Given the increasing demand for energy,along with the restructuring of the energy supply catalyzed by effor...Ocean mining activities have been ongoing for nearly 70 years,making great contributions to industrialization.Given the increasing demand for energy,along with the restructuring of the energy supply catalyzed by efforts to achieve a low-carbon economy,deep seabed mining will play an important role in addressing energy-and resource-related problems in the future.However,deep seabed mining remains in the exploratory stage,with many challenges presented by the high-pressure,low-temperature,and complex geologic and hydrodynamic environments in deep-sea mining areas,which are inaccessible to human activities.Thus,considerable efforts are required to ensure sustainable,economic,reliable,and safe deep seabed mining.This study reviews the latest advances in marine engineering geology and the environment related to deep-sea min-ing activities,presents a bibliometric analysis of the development of ocean mineral resources since the 1950s,summarizes the development,theory,and issues related to techniques for the three stages of ocean mining(i.e.,exploration,extraction,and closure),and discusses the engineering geology environment,geological disasters,in-situ monitoring techniques,envi-ronmental protection requirements,and environmental effects in detail.Finally,this paper gives some key conclusions and future perspectives to provide insights for subsequent studies and commercial mining operations.展开更多
Recent earthquakes in the Sichuan Province have contributed to significantly expand the existing ground-motion database for China with new,high-quality ground-motion records.This study investigated the compatibility o...Recent earthquakes in the Sichuan Province have contributed to significantly expand the existing ground-motion database for China with new,high-quality ground-motion records.This study investigated the compatibility of ground-motion prediction equations(GMPEs)established by the NGA-West2 project in the US and local GMPEs for China,with respect to magnitude scaling,distance scaling,and site scaling implied by recent Chinese strong-motion data.The NGA-West2 GMPEs for shallow crustal earthquakes in tectonically active regions are considerably more sophisticated than widely used previous models,particularly in China.Using a mixed-effects procedure,the study evaluated event terms(inter-event residuals)and intra-event residuals of Chinese data relative to the NGA-West2 GMPEs.Distance scaling was investigated by examining trends of intra-event residuals with source-to-site distance.Scaling with respect to site conditions was investigated by examining trends of intra-event residuals with soil type.The study also investigated other engineering characteristics of Chinese strong ground motions.In particular,the records were analyzed for evidence of pulse-like forward-directivity effects.The elastic median response spectra of the selected stations were compared to code-mandated design spectra for various mean return periods.Results showed that international and local GMPEs can be applied for seismic hazard analysis in Sichuan with minor modification of the regression coefficients related to the source-to-site distance and soil scaling.Specifically,the Chinese data attenuated faster than implied by the considered GMPEs and the differences were statistically significant in some cases.Near-source,pulse-like ground motions were identified at two recording stations for the 2008 Wenchuan earthquake,possibly implying rupture directivity.The median recorded spectra were consistent with the code-based spectra in terms of amplitude and shape.The new ground-motion data can be used to develop advanced ground-motion models for China and worldwide and,ultimately,for advancing probabilistic seismic hazard assessment(PSHA).展开更多
Mining activities often cause dramatic changes in landscapes, particularly in the dump sites and its surrounding environment. Land rehabilitation is the process of renovating damaged land to some extent of its origina...Mining activities often cause dramatic changes in landscapes, particularly in the dump sites and its surrounding environment. Land rehabilitation is the process of renovating damaged land to some extent of its original shape and aims to minimize and mitigate the environmental effects to allow new land uses. The success of different rehabilitation strategy and newly suggested urban and architecture modeling depends on the landscape characterization (topography of the study area and its derivatives such as slope and aspects, geological and geomorphologic nature of the study area). The aim of this study is to demonstrate the utility of different methodologies based on geomatics techniques (Photogrammetry, Remote Sensing, Global Positioning System (GPS) and three dimensional Geographic Information System (GIS)) for highlighting landscape characterization which is needed for rehabilitation of Mahis area. Photogrammetric adjustment procedures were used to create digital elevation model and Orth-Photo model for the study area using aerial images. Remote sensing data were used for land classification to provide vital information for rehabilitation planning. GPS field observations were used to build spatial network for the study area based on ground control point collections. Finally, realistic representation of the study area with three dimensional GIS was prepared for the study area considering ease and flexible updating of the geo-spatial database.展开更多
Retrogressive landslides in sensitive clays pose significant risks to nearby infrastructure,as natural toe erosion or localized disturbances can trigger progressive block failures.While prior studies have largely reli...Retrogressive landslides in sensitive clays pose significant risks to nearby infrastructure,as natural toe erosion or localized disturbances can trigger progressive block failures.While prior studies have largely relied on two-dimensional(2D)large-deformation analyses,such models overlook key three-dimensional(3D)failure mechanisms and variability effects.This study develops a 3D probabilistic framework by integrating the Coupled Eulerian–Lagrangian(CEL)method with random field theory to simulate retrogressive landslides in spatially variable clay.Using Monte Carlo simulations,we compare 2D and 3D random large-deformation models to evaluate failure modes,runout distances,sliding velocities,and influence zones.The 3D analyses captured more complex failure modes—such as lateral retrogression and asynchronous block mobilization across slope width.Additionally,the 3D analyses predict longer mean runout distances(13.76 vs.11.92 m),wider mean influence distance(11.35 vs.8.73 m),and higher mean sliding velocities(4.66 vs.3.94 m/s)than their 2D counterparts.Moreover,3D models exhibit lower coefficients of variation(e.g.,0.10 for runout distance)due to spatial averaging across slope width.Probabilistic hazard assessment shows that 2D models significantly underpredict near-field failure probabilities(e.g.,48.8%vs.89.9%at 12 m from the slope toe).These findings highlight the limitations of 2D analyses and the importance of multi-directional spatial variability for robust geohazard assessments.The proposed 3D framework enables more realistic prediction of landslide mobility and supports the design of safer,risk-informed infrastructure.展开更多
Change detection(CD)plays a crucial role in numerous fields,where both convolutional neural networks(CNNs)and Transformers have demonstrated exceptional performance in CD tasks.However,CNNs suffer from limited recepti...Change detection(CD)plays a crucial role in numerous fields,where both convolutional neural networks(CNNs)and Transformers have demonstrated exceptional performance in CD tasks.However,CNNs suffer from limited receptive fields,hindering their ability to capture global features,while Transformers are constrained by high computational complexity.Recently,Mamba architecture,which is based on state space models(SSMs),has shown powerful global modeling capabilities while achieving linear computational complexity.Although some researchers have incorporated Mamba into CD tasks,the existing Mamba⁃based remote sensing CD methods struggle to effectively perceive the inherent locality of changed regions when flattening and scanning remote sensing images,leading to limitations in extracting change features.To address these issues,we propose a novel Mamba⁃based CD method termed difference feature fusion Mamba model(DFFMamba)by mitigating the loss of feature locality caused by traditional Mamba⁃style scanning.Specifically,two distinct difference feature extraction modules are designed:Difference Mamba(DMamba)and local difference Mamba(LDMamba),where DMamba extracts difference features by calculating the difference in coefficient matrices between the state⁃space equations of the bi⁃temporal features.Building upon DMamba,LDMamba combines a locally adaptive state⁃space scanning(LASS)strategy to enhance feature locality so as to accurately extract difference features.Additionally,a fusion Mamba(FMamba)module is proposed,which employs a spatial⁃channel token modeling SSM(SCTMS)unit to integrate multi⁃dimensional spatio⁃temporal interactions of change features,thereby capturing their dependencies across both spatial and channel dimensions.To verify the effectiveness of the proposed DFFMamba,extensive experiments are conducted on three datasets of WHU⁃CD,LEVIR⁃CD,and CLCD.The results demonstrate that DFFMamba significantly outperforms state⁃of⁃the⁃art CD methods,achieving intersection over union(IoU)scores of 90.67%,85.04%,and 66.56%on the three datasets,respectively.展开更多
As global populations grow, the generation of various waste materials like fats, oils, and grease (FOG), fruit waste, and other perishable wastes increases concurrently. Disposal of these highly putrescible waste prod...As global populations grow, the generation of various waste materials like fats, oils, and grease (FOG), fruit waste, and other perishable wastes increases concurrently. Disposal of these highly putrescible waste products in landfills consumes valuable landfill space. Anaerobic digestion can transform these waste materials into valuable components, including fertilizer and biogas, reducing the demand for landfill space. The current study is based on the hypothesis that incorporating high-strength organic waste into conventional wastewater sludge can enhance the production of onsite biogas at wastewater treatment plants, therefore contributing to the reduction of the plant’s energy demands from the grid. The batch anaerobic biodegradability test assays were performed for 63 days to observe the impact on the biomethane yield from adding high-strength organic waste to the wastewater sludge and to investigate the combined effects of co-digesting two different preselected high-strength organic waste streams. Additionally, physicochemical characterization was performed on different fruit waste juicing residuals to indicate which fruit wastes might increase anaerobic digestion efficiency. The highest methane yield of 243 mL/gVS and 280 mL/gVS, respectively, were obtained with two mixtures having 10% FOG as the sole substrate and 10% FOG along with 10% fruit waste. The study also assessed the siloxane concentrations present as trace contaminants in the biogas samples. An initial economic feasibility assessment of food waste co-digestion at two wastewater treatment plants in Florida was conducted using the Co-Digestion Economic Analysis Tool (CoEAT) model. Based on the laboratory results, the analysis indicated a net positive benefit of $39,472 for a medium-sized plant (10 - 30 MGD capacity) and $52,488 for a larger plant (>30 MGD capacity) after 15 years, while diverting 10 - 18 tons/day of food waste from landfills with an anticipated minimal increase in sludge volume production at food waste additions less than 10% of the digester feed as stated in the literature.展开更多
This paper investigates the development and performance of a new higher-order geometric stiffness matrix that more closely approximates the theoretically derived stiffness coefficients.Factors that influence the accur...This paper investigates the development and performance of a new higher-order geometric stiffness matrix that more closely approximates the theoretically derived stiffness coefficients.Factors that influence the accuracy of the solution are studied using two columns,two braced frames,and one unbraced frame.Discussion is provided when the new geometric stiffness matrix can be used to improve the buckling load analysis results and when it may provide only nominal additional benefit.展开更多
This study presents a framework for the semi-automatic detection of rock discontinuities using a threedimensional(3D)point cloud(PC).The process begins by selecting an appropriate neighborhood size,a critical step for...This study presents a framework for the semi-automatic detection of rock discontinuities using a threedimensional(3D)point cloud(PC).The process begins by selecting an appropriate neighborhood size,a critical step for feature extraction from the PC.The effects of different neighborhood sizes(k=5,10,20,50,and 100)have been evaluated to assess their impact on classification performance.After that,17 geometric and spatial features were extracted from the PC.Next,ensemble methods,AdaBoost.M2,random forest,and decision tree,have been compared with Artificial Neural Networks to classify the main discontinuity sets.The McNemar test indicates that the classifiers are statistically significant.The random forest classifier consistently achieves the highest performance with an accuracy exceeding 95%when using a neighborhood size of k=100,while recall,F-score,and Cohen's Kappa also demonstrate high success.SHapley Additive exPlanations(SHAP),an Explainable AI technique,has been used to evaluate feature importance and improve the explainability of black-box machine learning models in the context of rock discontinuity classification.The analysis reveals that features such as normal vectors,verticality,and Z-values have the greatest influence on identifying main discontinuity sets,while linearity,planarity,and eigenvalues contribute less,making the model more transparent and easier to understand.After classification,individual discontinuity sets were detected using a revised DBSCAN from the main discontinuity sets.Finally,the orientation parameters of the plane fitted to each discontinuity were derived from the plane parameters obtained using the Random Sample Consensus(RANSAC).Two real-world datasets(obtained from SfM and LiDAR)and one synthetic dataset were used to validate the proposed method,which successfully identified rock discontinuities and their orientation parameters(dip angle/direction).展开更多
There is significant debate concerning the tectonic characteristics and evolutionary understanding of the South China Block(SCB)during the Early Mesozoic.One of the key points of contention is the tectonic-magmatic ac...There is significant debate concerning the tectonic characteristics and evolutionary understanding of the South China Block(SCB)during the Early Mesozoic.One of the key points of contention is the tectonic-magmatic activity during the Triassic and its dynamic mechanisms.However,research on the detailed chronology and tectonic settings of granite plutons in key regions remains insuffi-cient,limiting the understanding of the tectonic-magmatic dynamic mechanisms in the interior of SCB during the Triassic.In this contribution,we present whole-rock major and trace elemental data,Sr-Nd isotope data,LA-ICP-MS zircon U-Pb age dating,and Lu-Hf isotope data for granites of Dashenshan pluton in the Xiangzhong,northwest part of SCB.The results indicate that the Dashenshan granite has an emplacement age of 208.4-212.5 Ma,characterized by high SiO_(2),Na_(2)O,and K_(2)O contents and low MgO and CaO.The Dashenshan granite is enriched in light rare-earth elements with a significant negative Eu anomaly(averageδEu=0.42).It is also enriched in Rb,K,and Th and shows pronounced depletion in Nb,Ta,and Ti,classifying it as peraluminous calc-alkaline granite,specifically of the I-type.The zircon ε_(Hf(t)) values range from−8.39 to−4.4,with an average of−5.82,and the Sr-Nd isotopes are relatively enriched[ε_(Nd)(t)=−9.31 to−6.8].Combining these geochemical characteristics,it is revealed that the Dashenshan granite was derived from the partial melting of middle to upper crustal metamorphic basement materials under medium-to low-temperature conditions,with possible minor contributions from mantle-derived materials.Furthermore,it underwent fractional crystallization,including plagioclase differentiation.By integrating the geochemical features and spatial distribution of Triassic granites in SCB,this study suggests that the regional tectonic evolution of SCB during the Triassic was primarily controlled by the collision of the SCB with the Indochina Block and the North China Block.In Xiangzhong,the tectonic setting transitioned from syn-collisional compression to post-collisional extension during the Late Triassic.The Dashenshan pluton formed in a post-collisional extensional setting,resulting from the decompression melting of middle-to-upper crustal rocks.The upwelling of the asthenosphere and upward heat transfer likely played a significant role in the formation of the Dashenshan granitic magma.展开更多
Ultraviolet-visible(UV-Vis)and three-dimensional excitation emission matrix fluorescence(3D-EEM)spectroscopies were conducted to investigate the structure and origin of dissolved organic matter(DOM)from soils around t...Ultraviolet-visible(UV-Vis)and three-dimensional excitation emission matrix fluorescence(3D-EEM)spectroscopies were conducted to investigate the structure and origin of dissolved organic matter(DOM)from soils around the Tuo river in Suzhou city in different season.The results showed that the characteristics of all samples,UV-Visible spectra were similar and the relative concentrations of DOM showed an overall increasing trend in the middle and upper reaches of the Tuo River and reached a maximum in the middle reaches of the river.In particular,the aromaticity(A250/A365)of DOM in sediments at the midstream point of the Tuo River and the degree of humification degree(SUVA254)were higher than those in other river sections.The 3D-EEM fluorescence spectra showed that fulvic acid-like peaks in the visible region,fulvic acid-like peaks in the UV-visible region,and two humic acid-like peaks were reflected in the dissolved organic matter of the Tuo River sediments.Combining the three-dimensional fluorescence spectrum with the fluorescence index(fluorescence index,FI)and autochthonous index(autoch-thonous index,BIX)of DOM in the sediments of the Tuo River in different seasons,it shows that the exogenous input of DOM in the sediments of each section of the Tuo River is extremely obvious and less bioavailable.The aromaticity of DOM molecules is enhanced after the Tuo River flows through urban areas.The present study can provide a reference for the future management of the water environment of related rivers.展开更多
Tropical lakes such as Lake Sentarum in Kalimantan,Indonesia,represent ecologically rich ecosystems with high biodiversity and constitute the largest lake on the island of Kalimantan.This lake serves as a sensitive in...Tropical lakes such as Lake Sentarum in Kalimantan,Indonesia,represent ecologically rich ecosystems with high biodiversity and constitute the largest lake on the island of Kalimantan.This lake serves as a sensitive indicator of climate change;however,its monitoring is often hindered by persistent cloud cover.This study evaluates the effectiveness of a Gradient Tree Boosting machine learning model integrated with multisource satellite data,including optical imagery,Sentinel-1 SAR,Sentinel-2,and high resolution NICFI data,in accurately mapping surface water dynamics.The Gradient Tree Boosting model was trained and validated using water and non water samples collected from annual imagery spanning 2019 to 2024,achieving validation accuracies ranging from 80 percent to 97 percent.Results demonstrate that Gradient Tree Boosting successfully integrates the strengths of each sensor,producing consistent annual water maps despite extreme hydrological fluctuations caused by El Nino and La Nina events.These findings highlight the model’s potential application in water resource man-agement,particularly in providing accurate baseline data to support adaptation planning for droughts and floods in climate vulnerable regions.展开更多
This study investigates the morphological characteristics and evolutionary mechanisms of stream potholes in the granodiorite riverbed of the Quanfengtan reach,located in the lower Zijiang River,Hunan Province,China.Fi...This study investigates the morphological characteristics and evolutionary mechanisms of stream potholes in the granodiorite riverbed of the Quanfengtan reach,located in the lower Zijiang River,Hunan Province,China.Field surveys and statistical analyses reveal that these potholes exhibit diverse geometries(calibers:0.2-2.5 m;depths:0.03-1.98 m;depth-to-caliber ratios:0.08-1.63),predominantly elliptical and shallow,reflecting distinct developmental stages.These potholes show no spatial correlation with bedrock joints,and their long-axis orientations diverge from dominant joint trends.Instead,they exhibit consistent alignment with the river’s prevailing flow direction.Furthermore,pothole dimensions(e.g.,depth and diameter)strongly correlate with gravel size,indicating sediment-driven abrasion as the primary formation mechanism.The uplift of the Xuefeng Mountains relative to the Dongting Basin since the Late Quaternary,which drove the incision of the lower Zijiang River,transforming it from an alluvial channel to a bedrock-dominated channel,is the primary precondition enabling pothole development in this region.Additionally,the influence of climatic factors and human activities cannot be overlooked.The progressive formation,coalescence,and evolution of potholes into grooves constitute the primary mechanism driving riverbed erosion by the Zijiang River at Quanfengtan.展开更多
In the face of the unrelenting challenge posed by earthquakes-a natural hazard of unpredictable nature with a legacy of significant loss of life,destruction of infrastructure,and profound economic and social impacts-t...In the face of the unrelenting challenge posed by earthquakes-a natural hazard of unpredictable nature with a legacy of significant loss of life,destruction of infrastructure,and profound economic and social impacts-the scientific community has pursued advancements in earthquake early warning systems(EEWSs).These systems are vital for pre-emptive actions and decision-making that can save lives and safeguard critical infrastructure.This study proposes and validates a domain-informed deep learning-based EEWS called the hybrid earthquake early warning framework for estimating response spectra(HEWFERS),which represents a significant leap forward in the capabilities to predict ground shaking intensity in real-time,aligning with the United Nations’disaster risk reduction goals.HEWFERS ingeniously integrates a domain-informed variational autoencoder for physics-based latent variable(LV)extraction,a feed-forward neural network for on-site prediction,and Gaussian process regression for spatial prediction.Adopting explainable artificial intelligence-based Shapley explanations further elucidates the predictive mechanisms,ensuring stakeholder-informed decisions.By conducting an extensive analysis of the proposed framework under a large database of approximately 14000 recorded ground motions,this study offers insights into the potential of integrating machine learning with seismology to revolutionize earthquake preparedness and response,thus paving the way for a safer and more resilient future.展开更多
Ionospheric disturbances caused by acoustic waves emitted during earthquakes were studied using the Global Navigation Satellite System(GNSS)to analyze the changes in total electron content(TEC)values.GNSS signals norm...Ionospheric disturbances caused by acoustic waves emitted during earthquakes were studied using the Global Navigation Satellite System(GNSS)to analyze the changes in total electron content(TEC)values.GNSS signals normally propagate from satellites to receivers through the ionosphere layer.The delayed signals can be used to obtain TEC values by passing through the layer.Therefore,this study aims to analyze Coseismic Ionospheric Disturbances(CIDs)in six earthquakes,including 2016 M7.8 New Zealand(about 0.49 TECU),2018 M7.9 Alaska(about 0.20 TECU),2005 M7.2 California(about 0.29 TECU),2023 M7.5 Turkey(about 0.49 TECU),2012 M8.6 Sumatra(about 2.98 TECU),and 2012 M8.2 Sumatra(about 1.49 TECU)earthquakes.The propagation speed of the wave from the earthquake epicenter,identified as an acoustic wave,was estimated to be between 0.6 and 1.0 km/s.The 3D tomography modeling was performed to analyze the TEC height variations in the ionosphere to obtain a more accurate spatial analysis of TEC due to earthquakes.Moreover,checkerboard accuracy tests were applied to test the resolution of the 3D tomography model.The maximum ionization correlation test was also conducted for the six earthquakes to determine variations in the maximum ionization height of the ionosphere.The correlation test results between magnitude and maximum CID height produced a moderate correlation.The greater the earthquake magnitude,the higher the maximum CID detected.This is because greater earthquake produces compressed energy,which reduces the ionospheric density and reaches the maximum height.In addition,the maximum CID height is higher at night than in the afternoon because the E layer disappears at night.展开更多
0 INTRODUCTION Microplastics are defined as small plastic debris(1μm-5 mm),which have complex properties of widerange densities(0.05-2.3 g/cm^3),diverse shapes(e.g.,beads,fibers,foam and pellets)and low degradability...0 INTRODUCTION Microplastics are defined as small plastic debris(1μm-5 mm),which have complex properties of widerange densities(0.05-2.3 g/cm^3),diverse shapes(e.g.,beads,fibers,foam and pellets)and low degradability(Harris,2020;Chubarenko et al.,2016).展开更多
1.Introduction The global transition to green energy has created an unprecedented demand for critical metals and energy resources such as cobalt,nickel,copper,manganese,rare earth elements,and gas hydrates.Against thi...1.Introduction The global transition to green energy has created an unprecedented demand for critical metals and energy resources such as cobalt,nickel,copper,manganese,rare earth elements,and gas hydrates.Against this strategic backdrop,deep-sea mineral and energy resources are increasingly viewed as essential supplements to terrestrial supply bottlenecks and as strategic safeguards for the future low-carbon economy.The international seabed forms a vast strategic resource of global significance,offering great potential to support energy transition and security.Therefore,under sound scientific evaluation and strict regulation,prudent development of this resource should serve both economic needs and the broader goals of sustainable energy transformation[1].展开更多
Developing low-permeability Coalbed Methane(CBM)reservoirs can significantly benefit from a comprehensive understanding of hydraulic fracture nucleation and propagation mechanisms,particularly in anthracite CBM reserv...Developing low-permeability Coalbed Methane(CBM)reservoirs can significantly benefit from a comprehensive understanding of hydraulic fracture nucleation and propagation mechanisms,particularly in anthracite CBM reservoirs.This study employs true-triaxial hydraulic fracturing experiments to investigate these mechanisms,with variables including injection flow rate,horizontal stress difference(σH-σh),and bedding orientation.Additionally,we conduct corresponding numerical cases to validate the experimental conclusions.The research also considers re-fracturing instances.For the first time,we utilize a combination of Kaiser tests and the stress transfer function in ANSYS Workbench finite element analysis to accurately restore the confining pressure of the coal sample.The findings suggest that a high initial injection flow rate during hydraulic fracturing can promote fluid leakage and aid in maintaining substantial fracture pressure.Enhanced fracturing efficiency can be achieved through higher injection rates,and it can ensure optimal fracturing efficiency,minimizing roof and floor fracturing in coal reservoirs to prevent fracturing fluid leakage.The presence of a high horizontal stress difference facilitates hydraulic fracture propagation along the direction of the maximum horizontal compressive stress,requiring a greater hydraulic pressure to produce more fracture systems in coal reservoirs.Additionally,a minor deviation in the wellbore injection direction from the bedding orientation assists in creating a complex hydraulic fractured network,although this also requires higher hydraulic pressure to initiate new fractures.In the case of multiple hydraulic fracturing,the second initiation pressure tends to be significantly higher than the first,indicating that a sequential increase in hydraulic pressure aids the formation of additional fractures.Moreover,a simplified numerical simulation has been conducted to corroborate the experimental findings.These insights are crucial in optimizing hydraulic fracturing processes to enhance the permeability of anthracite CBM reservoirs.展开更多
The intricate network of bilateral trade relationships among Pacific Rim countries(PRCs),along with the associated embodied carbon flows plays a pivotal role in shaping global carbon emission patterns and dynamics.Thi...The intricate network of bilateral trade relationships among Pacific Rim countries(PRCs),along with the associated embodied carbon flows plays a pivotal role in shaping global carbon emission patterns and dynamics.This study employs a multi-regional inputoutput analysis and a symbiotic degree model to explore the symbiotic effects of trade-embodied carbon flows between China and PRCs.We show that between 2009 and 2021,China's trade-embodied carbon exports to PRCs surged from 214.20 million tons to 614.80 million tons,driven largely by mechanical and electronic equipment.The share of the United States,Japan,and South Korea in China's total embodied carbon exports to PRCs has declined,whereas Southeast Asian countries have emerged as the primary source of China's embodied carbon imports.The degree of symbiosis in trade-embodied carbon between China and PRCs shifted from negative to positive,indicating a gradual trend toward positive asymmetric symbiosis.Moreover,China's role in regional trade-embodied carbon flows has transitioned from passive to active,with its influence particularly pronounced in countries such as Vietnam,Thailand,Japan,South Korea,and Russia.展开更多
基金Funding for this research was provided by the National Natural Science Foundation of China (42022052,42277138,and 52108337)the National Key R&D Program of China (2022YFC2803800)+1 种基金the Shandong Provincial Natural Science Foundation (ZR2020YQ29)UCL's Department of Civil,Environmental and Geomatic Engineering,and Ocean University of China.
文摘Ocean mining activities have been ongoing for nearly 70 years,making great contributions to industrialization.Given the increasing demand for energy,along with the restructuring of the energy supply catalyzed by efforts to achieve a low-carbon economy,deep seabed mining will play an important role in addressing energy-and resource-related problems in the future.However,deep seabed mining remains in the exploratory stage,with many challenges presented by the high-pressure,low-temperature,and complex geologic and hydrodynamic environments in deep-sea mining areas,which are inaccessible to human activities.Thus,considerable efforts are required to ensure sustainable,economic,reliable,and safe deep seabed mining.This study reviews the latest advances in marine engineering geology and the environment related to deep-sea min-ing activities,presents a bibliometric analysis of the development of ocean mineral resources since the 1950s,summarizes the development,theory,and issues related to techniques for the three stages of ocean mining(i.e.,exploration,extraction,and closure),and discusses the engineering geology environment,geological disasters,in-situ monitoring techniques,envi-ronmental protection requirements,and environmental effects in detail.Finally,this paper gives some key conclusions and future perspectives to provide insights for subsequent studies and commercial mining operations.
基金Community Based Disaster Management in Asia Programme Phase Ⅱ (CBDM Asia Phase Ⅱ) (00084327)
文摘Recent earthquakes in the Sichuan Province have contributed to significantly expand the existing ground-motion database for China with new,high-quality ground-motion records.This study investigated the compatibility of ground-motion prediction equations(GMPEs)established by the NGA-West2 project in the US and local GMPEs for China,with respect to magnitude scaling,distance scaling,and site scaling implied by recent Chinese strong-motion data.The NGA-West2 GMPEs for shallow crustal earthquakes in tectonically active regions are considerably more sophisticated than widely used previous models,particularly in China.Using a mixed-effects procedure,the study evaluated event terms(inter-event residuals)and intra-event residuals of Chinese data relative to the NGA-West2 GMPEs.Distance scaling was investigated by examining trends of intra-event residuals with source-to-site distance.Scaling with respect to site conditions was investigated by examining trends of intra-event residuals with soil type.The study also investigated other engineering characteristics of Chinese strong ground motions.In particular,the records were analyzed for evidence of pulse-like forward-directivity effects.The elastic median response spectra of the selected stations were compared to code-mandated design spectra for various mean return periods.Results showed that international and local GMPEs can be applied for seismic hazard analysis in Sichuan with minor modification of the regression coefficients related to the source-to-site distance and soil scaling.Specifically,the Chinese data attenuated faster than implied by the considered GMPEs and the differences were statistically significant in some cases.Near-source,pulse-like ground motions were identified at two recording stations for the 2008 Wenchuan earthquake,possibly implying rupture directivity.The median recorded spectra were consistent with the code-based spectra in terms of amplitude and shape.The new ground-motion data can be used to develop advanced ground-motion models for China and worldwide and,ultimately,for advancing probabilistic seismic hazard assessment(PSHA).
文摘Mining activities often cause dramatic changes in landscapes, particularly in the dump sites and its surrounding environment. Land rehabilitation is the process of renovating damaged land to some extent of its original shape and aims to minimize and mitigate the environmental effects to allow new land uses. The success of different rehabilitation strategy and newly suggested urban and architecture modeling depends on the landscape characterization (topography of the study area and its derivatives such as slope and aspects, geological and geomorphologic nature of the study area). The aim of this study is to demonstrate the utility of different methodologies based on geomatics techniques (Photogrammetry, Remote Sensing, Global Positioning System (GPS) and three dimensional Geographic Information System (GIS)) for highlighting landscape characterization which is needed for rehabilitation of Mahis area. Photogrammetric adjustment procedures were used to create digital elevation model and Orth-Photo model for the study area using aerial images. Remote sensing data were used for land classification to provide vital information for rehabilitation planning. GPS field observations were used to build spatial network for the study area based on ground control point collections. Finally, realistic representation of the study area with three dimensional GIS was prepared for the study area considering ease and flexible updating of the geo-spatial database.
基金supported by the National Key Research and Development Program of China(No.2024YFC2815400)the European Commission(Nos.HORIZON MSCA-2024-PF-01 and 101200637)+2 种基金the Opening Fund of the State Key Laboratory of Water Resources Engineering and Management at Wuhan University(No.2024SGG07)the Shandong Provincial Natural Science Foundation(No.ZR2025MS647)the Sand Hazards and Opportunities for Resilience,Energy,and Sustainability(SHORES)Center,funded by Tamkeen under the NYUAD Research Institute Award CG013.
文摘Retrogressive landslides in sensitive clays pose significant risks to nearby infrastructure,as natural toe erosion or localized disturbances can trigger progressive block failures.While prior studies have largely relied on two-dimensional(2D)large-deformation analyses,such models overlook key three-dimensional(3D)failure mechanisms and variability effects.This study develops a 3D probabilistic framework by integrating the Coupled Eulerian–Lagrangian(CEL)method with random field theory to simulate retrogressive landslides in spatially variable clay.Using Monte Carlo simulations,we compare 2D and 3D random large-deformation models to evaluate failure modes,runout distances,sliding velocities,and influence zones.The 3D analyses captured more complex failure modes—such as lateral retrogression and asynchronous block mobilization across slope width.Additionally,the 3D analyses predict longer mean runout distances(13.76 vs.11.92 m),wider mean influence distance(11.35 vs.8.73 m),and higher mean sliding velocities(4.66 vs.3.94 m/s)than their 2D counterparts.Moreover,3D models exhibit lower coefficients of variation(e.g.,0.10 for runout distance)due to spatial averaging across slope width.Probabilistic hazard assessment shows that 2D models significantly underpredict near-field failure probabilities(e.g.,48.8%vs.89.9%at 12 m from the slope toe).These findings highlight the limitations of 2D analyses and the importance of multi-directional spatial variability for robust geohazard assessments.The proposed 3D framework enables more realistic prediction of landslide mobility and supports the design of safer,risk-informed infrastructure.
基金supported by the National Natural Science Foundation of China(Nos.42371449,41801386).
文摘Change detection(CD)plays a crucial role in numerous fields,where both convolutional neural networks(CNNs)and Transformers have demonstrated exceptional performance in CD tasks.However,CNNs suffer from limited receptive fields,hindering their ability to capture global features,while Transformers are constrained by high computational complexity.Recently,Mamba architecture,which is based on state space models(SSMs),has shown powerful global modeling capabilities while achieving linear computational complexity.Although some researchers have incorporated Mamba into CD tasks,the existing Mamba⁃based remote sensing CD methods struggle to effectively perceive the inherent locality of changed regions when flattening and scanning remote sensing images,leading to limitations in extracting change features.To address these issues,we propose a novel Mamba⁃based CD method termed difference feature fusion Mamba model(DFFMamba)by mitigating the loss of feature locality caused by traditional Mamba⁃style scanning.Specifically,two distinct difference feature extraction modules are designed:Difference Mamba(DMamba)and local difference Mamba(LDMamba),where DMamba extracts difference features by calculating the difference in coefficient matrices between the state⁃space equations of the bi⁃temporal features.Building upon DMamba,LDMamba combines a locally adaptive state⁃space scanning(LASS)strategy to enhance feature locality so as to accurately extract difference features.Additionally,a fusion Mamba(FMamba)module is proposed,which employs a spatial⁃channel token modeling SSM(SCTMS)unit to integrate multi⁃dimensional spatio⁃temporal interactions of change features,thereby capturing their dependencies across both spatial and channel dimensions.To verify the effectiveness of the proposed DFFMamba,extensive experiments are conducted on three datasets of WHU⁃CD,LEVIR⁃CD,and CLCD.The results demonstrate that DFFMamba significantly outperforms state⁃of⁃the⁃art CD methods,achieving intersection over union(IoU)scores of 90.67%,85.04%,and 66.56%on the three datasets,respectively.
文摘As global populations grow, the generation of various waste materials like fats, oils, and grease (FOG), fruit waste, and other perishable wastes increases concurrently. Disposal of these highly putrescible waste products in landfills consumes valuable landfill space. Anaerobic digestion can transform these waste materials into valuable components, including fertilizer and biogas, reducing the demand for landfill space. The current study is based on the hypothesis that incorporating high-strength organic waste into conventional wastewater sludge can enhance the production of onsite biogas at wastewater treatment plants, therefore contributing to the reduction of the plant’s energy demands from the grid. The batch anaerobic biodegradability test assays were performed for 63 days to observe the impact on the biomethane yield from adding high-strength organic waste to the wastewater sludge and to investigate the combined effects of co-digesting two different preselected high-strength organic waste streams. Additionally, physicochemical characterization was performed on different fruit waste juicing residuals to indicate which fruit wastes might increase anaerobic digestion efficiency. The highest methane yield of 243 mL/gVS and 280 mL/gVS, respectively, were obtained with two mixtures having 10% FOG as the sole substrate and 10% FOG along with 10% fruit waste. The study also assessed the siloxane concentrations present as trace contaminants in the biogas samples. An initial economic feasibility assessment of food waste co-digestion at two wastewater treatment plants in Florida was conducted using the Co-Digestion Economic Analysis Tool (CoEAT) model. Based on the laboratory results, the analysis indicated a net positive benefit of $39,472 for a medium-sized plant (10 - 30 MGD capacity) and $52,488 for a larger plant (>30 MGD capacity) after 15 years, while diverting 10 - 18 tons/day of food waste from landfills with an anticipated minimal increase in sludge volume production at food waste additions less than 10% of the digester feed as stated in the literature.
文摘This paper investigates the development and performance of a new higher-order geometric stiffness matrix that more closely approximates the theoretically derived stiffness coefficients.Factors that influence the accuracy of the solution are studied using two columns,two braced frames,and one unbraced frame.Discussion is provided when the new geometric stiffness matrix can be used to improve the buckling load analysis results and when it may provide only nominal additional benefit.
文摘This study presents a framework for the semi-automatic detection of rock discontinuities using a threedimensional(3D)point cloud(PC).The process begins by selecting an appropriate neighborhood size,a critical step for feature extraction from the PC.The effects of different neighborhood sizes(k=5,10,20,50,and 100)have been evaluated to assess their impact on classification performance.After that,17 geometric and spatial features were extracted from the PC.Next,ensemble methods,AdaBoost.M2,random forest,and decision tree,have been compared with Artificial Neural Networks to classify the main discontinuity sets.The McNemar test indicates that the classifiers are statistically significant.The random forest classifier consistently achieves the highest performance with an accuracy exceeding 95%when using a neighborhood size of k=100,while recall,F-score,and Cohen's Kappa also demonstrate high success.SHapley Additive exPlanations(SHAP),an Explainable AI technique,has been used to evaluate feature importance and improve the explainability of black-box machine learning models in the context of rock discontinuity classification.The analysis reveals that features such as normal vectors,verticality,and Z-values have the greatest influence on identifying main discontinuity sets,while linearity,planarity,and eigenvalues contribute less,making the model more transparent and easier to understand.After classification,individual discontinuity sets were detected using a revised DBSCAN from the main discontinuity sets.Finally,the orientation parameters of the plane fitted to each discontinuity were derived from the plane parameters obtained using the Random Sample Consensus(RANSAC).Two real-world datasets(obtained from SfM and LiDAR)and one synthetic dataset were used to validate the proposed method,which successfully identified rock discontinuities and their orientation parameters(dip angle/direction).
基金supported financially by the Research Foundation of the Department of Natural Resources of Hunan Province(20230135DZ)the Provincial Natural Science Foundation of Hunan(2024JJ7080)+1 种基金the Scientific Research Fund of Hunan Provincial Education Department(23C0320)Hunan Provincial College Student Innovation and Entrepreneurship Training Project(S202311527014).
文摘There is significant debate concerning the tectonic characteristics and evolutionary understanding of the South China Block(SCB)during the Early Mesozoic.One of the key points of contention is the tectonic-magmatic activity during the Triassic and its dynamic mechanisms.However,research on the detailed chronology and tectonic settings of granite plutons in key regions remains insuffi-cient,limiting the understanding of the tectonic-magmatic dynamic mechanisms in the interior of SCB during the Triassic.In this contribution,we present whole-rock major and trace elemental data,Sr-Nd isotope data,LA-ICP-MS zircon U-Pb age dating,and Lu-Hf isotope data for granites of Dashenshan pluton in the Xiangzhong,northwest part of SCB.The results indicate that the Dashenshan granite has an emplacement age of 208.4-212.5 Ma,characterized by high SiO_(2),Na_(2)O,and K_(2)O contents and low MgO and CaO.The Dashenshan granite is enriched in light rare-earth elements with a significant negative Eu anomaly(averageδEu=0.42).It is also enriched in Rb,K,and Th and shows pronounced depletion in Nb,Ta,and Ti,classifying it as peraluminous calc-alkaline granite,specifically of the I-type.The zircon ε_(Hf(t)) values range from−8.39 to−4.4,with an average of−5.82,and the Sr-Nd isotopes are relatively enriched[ε_(Nd)(t)=−9.31 to−6.8].Combining these geochemical characteristics,it is revealed that the Dashenshan granite was derived from the partial melting of middle to upper crustal metamorphic basement materials under medium-to low-temperature conditions,with possible minor contributions from mantle-derived materials.Furthermore,it underwent fractional crystallization,including plagioclase differentiation.By integrating the geochemical features and spatial distribution of Triassic granites in SCB,this study suggests that the regional tectonic evolution of SCB during the Triassic was primarily controlled by the collision of the SCB with the Indochina Block and the North China Block.In Xiangzhong,the tectonic setting transitioned from syn-collisional compression to post-collisional extension during the Late Triassic.The Dashenshan pluton formed in a post-collisional extensional setting,resulting from the decompression melting of middle-to-upper crustal rocks.The upwelling of the asthenosphere and upward heat transfer likely played a significant role in the formation of the Dashenshan granitic magma.
文摘Ultraviolet-visible(UV-Vis)and three-dimensional excitation emission matrix fluorescence(3D-EEM)spectroscopies were conducted to investigate the structure and origin of dissolved organic matter(DOM)from soils around the Tuo river in Suzhou city in different season.The results showed that the characteristics of all samples,UV-Visible spectra were similar and the relative concentrations of DOM showed an overall increasing trend in the middle and upper reaches of the Tuo River and reached a maximum in the middle reaches of the river.In particular,the aromaticity(A250/A365)of DOM in sediments at the midstream point of the Tuo River and the degree of humification degree(SUVA254)were higher than those in other river sections.The 3D-EEM fluorescence spectra showed that fulvic acid-like peaks in the visible region,fulvic acid-like peaks in the UV-visible region,and two humic acid-like peaks were reflected in the dissolved organic matter of the Tuo River sediments.Combining the three-dimensional fluorescence spectrum with the fluorescence index(fluorescence index,FI)and autochthonous index(autoch-thonous index,BIX)of DOM in the sediments of the Tuo River in different seasons,it shows that the exogenous input of DOM in the sediments of each section of the Tuo River is extremely obvious and less bioavailable.The aromaticity of DOM molecules is enhanced after the Tuo River flows through urban areas.The present study can provide a reference for the future management of the water environment of related rivers.
文摘Tropical lakes such as Lake Sentarum in Kalimantan,Indonesia,represent ecologically rich ecosystems with high biodiversity and constitute the largest lake on the island of Kalimantan.This lake serves as a sensitive indicator of climate change;however,its monitoring is often hindered by persistent cloud cover.This study evaluates the effectiveness of a Gradient Tree Boosting machine learning model integrated with multisource satellite data,including optical imagery,Sentinel-1 SAR,Sentinel-2,and high resolution NICFI data,in accurately mapping surface water dynamics.The Gradient Tree Boosting model was trained and validated using water and non water samples collected from annual imagery spanning 2019 to 2024,achieving validation accuracies ranging from 80 percent to 97 percent.Results demonstrate that Gradient Tree Boosting successfully integrates the strengths of each sensor,producing consistent annual water maps despite extreme hydrological fluctuations caused by El Nino and La Nina events.These findings highlight the model’s potential application in water resource man-agement,particularly in providing accurate baseline data to support adaptation planning for droughts and floods in climate vulnerable regions.
基金the National Natural Science Foundation of China(Grant No.42101005)the Hunan Provincial Natural Science Foundation of China(Grant No.2025JJ50182)the Scientific Research Fund of Hunan Provincial Education Department(Grant No.24A0582).
文摘This study investigates the morphological characteristics and evolutionary mechanisms of stream potholes in the granodiorite riverbed of the Quanfengtan reach,located in the lower Zijiang River,Hunan Province,China.Field surveys and statistical analyses reveal that these potholes exhibit diverse geometries(calibers:0.2-2.5 m;depths:0.03-1.98 m;depth-to-caliber ratios:0.08-1.63),predominantly elliptical and shallow,reflecting distinct developmental stages.These potholes show no spatial correlation with bedrock joints,and their long-axis orientations diverge from dominant joint trends.Instead,they exhibit consistent alignment with the river’s prevailing flow direction.Furthermore,pothole dimensions(e.g.,depth and diameter)strongly correlate with gravel size,indicating sediment-driven abrasion as the primary formation mechanism.The uplift of the Xuefeng Mountains relative to the Dongting Basin since the Late Quaternary,which drove the incision of the lower Zijiang River,transforming it from an alluvial channel to a bedrock-dominated channel,is the primary precondition enabling pothole development in this region.Additionally,the influence of climatic factors and human activities cannot be overlooked.The progressive formation,coalescence,and evolution of potholes into grooves constitute the primary mechanism driving riverbed erosion by the Zijiang River at Quanfengtan.
基金the financial support from the Chilean National Research and Development Agency(Agencia Nacional de Investigación y Desarrollo,ANID)through Fondo Nacional de Desarrollo Científico y Tecnológico(FONDECYT)Regular 1240503Fondo de Valorización de la Investigación(FOVI)230030 projectsthe financial support from the ANID through FONDECYT Reg-ular 1240501.
文摘In the face of the unrelenting challenge posed by earthquakes-a natural hazard of unpredictable nature with a legacy of significant loss of life,destruction of infrastructure,and profound economic and social impacts-the scientific community has pursued advancements in earthquake early warning systems(EEWSs).These systems are vital for pre-emptive actions and decision-making that can save lives and safeguard critical infrastructure.This study proposes and validates a domain-informed deep learning-based EEWS called the hybrid earthquake early warning framework for estimating response spectra(HEWFERS),which represents a significant leap forward in the capabilities to predict ground shaking intensity in real-time,aligning with the United Nations’disaster risk reduction goals.HEWFERS ingeniously integrates a domain-informed variational autoencoder for physics-based latent variable(LV)extraction,a feed-forward neural network for on-site prediction,and Gaussian process regression for spatial prediction.Adopting explainable artificial intelligence-based Shapley explanations further elucidates the predictive mechanisms,ensuring stakeholder-informed decisions.By conducting an extensive analysis of the proposed framework under a large database of approximately 14000 recorded ground motions,this study offers insights into the potential of integrating machine learning with seismology to revolutionize earthquake preparedness and response,thus paving the way for a safer and more resilient future.
基金supported by the Master's Thesis Research Program of the Ministry of Education and Culture of the Republic of Indonesia,Sepuluh Nopember Institute of Technology with grant number 2002/PKS/ITS/2023 contract number 112/E5/PG.02.00.PL/2023.
文摘Ionospheric disturbances caused by acoustic waves emitted during earthquakes were studied using the Global Navigation Satellite System(GNSS)to analyze the changes in total electron content(TEC)values.GNSS signals normally propagate from satellites to receivers through the ionosphere layer.The delayed signals can be used to obtain TEC values by passing through the layer.Therefore,this study aims to analyze Coseismic Ionospheric Disturbances(CIDs)in six earthquakes,including 2016 M7.8 New Zealand(about 0.49 TECU),2018 M7.9 Alaska(about 0.20 TECU),2005 M7.2 California(about 0.29 TECU),2023 M7.5 Turkey(about 0.49 TECU),2012 M8.6 Sumatra(about 2.98 TECU),and 2012 M8.2 Sumatra(about 1.49 TECU)earthquakes.The propagation speed of the wave from the earthquake epicenter,identified as an acoustic wave,was estimated to be between 0.6 and 1.0 km/s.The 3D tomography modeling was performed to analyze the TEC height variations in the ionosphere to obtain a more accurate spatial analysis of TEC due to earthquakes.Moreover,checkerboard accuracy tests were applied to test the resolution of the 3D tomography model.The maximum ionization correlation test was also conducted for the six earthquakes to determine variations in the maximum ionization height of the ionosphere.The correlation test results between magnitude and maximum CID height produced a moderate correlation.The greater the earthquake magnitude,the higher the maximum CID detected.This is because greater earthquake produces compressed energy,which reduces the ionospheric density and reaches the maximum height.In addition,the maximum CID height is higher at night than in the afternoon because the E layer disappears at night.
基金the National Natural Science Foundation of China(No.42277138)the National Key Research and Development Program of China(Nos.2024YFF0506803 and 2024YFC2815400)+2 种基金the Fundamental Research Funds for the Central Universities(Nos.202441003 and 202513032)the Shandong Province National-Level Leading Talent Supporting Project(No.2022GJJLJRC-15)the European Commission(Nos.HORIZON MSCA-2024-PF-01,101200637)。
文摘0 INTRODUCTION Microplastics are defined as small plastic debris(1μm-5 mm),which have complex properties of widerange densities(0.05-2.3 g/cm^3),diverse shapes(e.g.,beads,fibers,foam and pellets)and low degradability(Harris,2020;Chubarenko et al.,2016).
基金financial support from the National Key R&D Program of China(No.2024YFC2815400)the Young Taishan Scholars Program(No.TSQN202507107)+1 种基金the Shandong Natural Science Foundation(No.ZR2025MS647)the European Commission(HORIZON MSCA-2024-PF-01,101200637).
文摘1.Introduction The global transition to green energy has created an unprecedented demand for critical metals and energy resources such as cobalt,nickel,copper,manganese,rare earth elements,and gas hydrates.Against this strategic backdrop,deep-sea mineral and energy resources are increasingly viewed as essential supplements to terrestrial supply bottlenecks and as strategic safeguards for the future low-carbon economy.The international seabed forms a vast strategic resource of global significance,offering great potential to support energy transition and security.Therefore,under sound scientific evaluation and strict regulation,prudent development of this resource should serve both economic needs and the broader goals of sustainable energy transformation[1].
基金funded by the National Natural Science Foundation of China(No.42202155)China Postdoctoral Science Foundation(No.2021MD703807)+7 种基金Heilongjiang Provincial Postdoctoral Science Foundation(No.LBH-Z20121)financial support from the China Scholarship Council(No.202008230018)the Research Fund Program of Hubei Key Laboratory of Resources and Eco-Environment Geology(No.HBREGKFJJ-202309)funding by the DGICYT Spanish Project(grant no.PID2020-118999GB-I00)funded by the MCIN/AEI/10.13039/501100011033funding by the Ramón y Cajal fellowship(grant no.RyC-2018-026335-I)funded by the MCIN/AEI/10.13039/50110001103the European Social Fund-Investing in Your Future.
文摘Developing low-permeability Coalbed Methane(CBM)reservoirs can significantly benefit from a comprehensive understanding of hydraulic fracture nucleation and propagation mechanisms,particularly in anthracite CBM reservoirs.This study employs true-triaxial hydraulic fracturing experiments to investigate these mechanisms,with variables including injection flow rate,horizontal stress difference(σH-σh),and bedding orientation.Additionally,we conduct corresponding numerical cases to validate the experimental conclusions.The research also considers re-fracturing instances.For the first time,we utilize a combination of Kaiser tests and the stress transfer function in ANSYS Workbench finite element analysis to accurately restore the confining pressure of the coal sample.The findings suggest that a high initial injection flow rate during hydraulic fracturing can promote fluid leakage and aid in maintaining substantial fracture pressure.Enhanced fracturing efficiency can be achieved through higher injection rates,and it can ensure optimal fracturing efficiency,minimizing roof and floor fracturing in coal reservoirs to prevent fracturing fluid leakage.The presence of a high horizontal stress difference facilitates hydraulic fracture propagation along the direction of the maximum horizontal compressive stress,requiring a greater hydraulic pressure to produce more fracture systems in coal reservoirs.Additionally,a minor deviation in the wellbore injection direction from the bedding orientation assists in creating a complex hydraulic fractured network,although this also requires higher hydraulic pressure to initiate new fractures.In the case of multiple hydraulic fracturing,the second initiation pressure tends to be significantly higher than the first,indicating that a sequential increase in hydraulic pressure aids the formation of additional fractures.Moreover,a simplified numerical simulation has been conducted to corroborate the experimental findings.These insights are crucial in optimizing hydraulic fracturing processes to enhance the permeability of anthracite CBM reservoirs.
基金National Natural Science Foundation of China,No.42201258,No.42571214Ministry of Education Humanities and Social Sciences Research Youth Fund Project,No.22YJCZH057+2 种基金National Key Research and Development Program of China,No.2024YFE0214000The Project of Jinhua City’s Deepening of Local Cooperation between China and Africa in 2025,No.SXZF202548ZSpecial Major Project of National Influence Building Think Tank,No.ZKZD2024011。
文摘The intricate network of bilateral trade relationships among Pacific Rim countries(PRCs),along with the associated embodied carbon flows plays a pivotal role in shaping global carbon emission patterns and dynamics.This study employs a multi-regional inputoutput analysis and a symbiotic degree model to explore the symbiotic effects of trade-embodied carbon flows between China and PRCs.We show that between 2009 and 2021,China's trade-embodied carbon exports to PRCs surged from 214.20 million tons to 614.80 million tons,driven largely by mechanical and electronic equipment.The share of the United States,Japan,and South Korea in China's total embodied carbon exports to PRCs has declined,whereas Southeast Asian countries have emerged as the primary source of China's embodied carbon imports.The degree of symbiosis in trade-embodied carbon between China and PRCs shifted from negative to positive,indicating a gradual trend toward positive asymmetric symbiosis.Moreover,China's role in regional trade-embodied carbon flows has transitioned from passive to active,with its influence particularly pronounced in countries such as Vietnam,Thailand,Japan,South Korea,and Russia.
