Magnitude estimation is a critical task in seismology,and conventional methods usually require dense seismic station arrays to provide data with sufficient spatiotemporal distribution.In this context,we propose the Ea...Magnitude estimation is a critical task in seismology,and conventional methods usually require dense seismic station arrays to provide data with sufficient spatiotemporal distribution.In this context,we propose the Earthquake Graph Network(EQGraphNet)to enhance the performance of single-station magnitude estimation.The backbone of the proposed model consists of eleven convolutional neural network layers and ten RCGL modules,where a RCGL combines a Residual Connection and a Graph convolutional Layer capable of mitigating the over-smoothing problem and simultaneously extracting temporal features of seismic signals.Our work uses the STanford EArthquake Dataset for model training and performance testing.Compared with three existing deep learning models,EQGraphNet demonstrates improved accuracy for both local magnitude and duration magnitude scales.To evaluate the robustness,we add natural background noise to the model input and find that EQGraphNet achieves the best results,particularly for signals with lower signal-to-noise ratios.Additionally,by replacing various network components and comparing their estimation performances,we illustrate the contribution of each part of EQGraphNet,validating the rationality of our approach.We also demonstrate the generalization capability of our model across different earthquakes occurring environments,achieving mean errors of±0.1 units.Furthermore,by demonstrating the effectiveness of deeper architectures,this work encourages further exploration of deeper GNN models for both multi-station and single-station magnitude estimation.展开更多
The distribution of Coulomb failure stress （CFS） change in the steep excavation slope is calculated by finite element method in this paper, and the failure mechanics under different conditions have been investigated...The distribution of Coulomb failure stress （CFS） change in the steep excavation slope is calculated by finite element method in this paper, and the failure mechanics under different conditions have been investigated. Comparing the CFSs before and after the slope excavation （stress loading and unloading processes）, the dangerous internal zone and the most likely failure external area are attained. Given the shear cracks on the top surface while tensile stress or cracks along the toe of the slope, we analyze the high cutting-angle steep slope in Kaixian county of the Three Gorges Reservoir region. We bring forward that the peak value of CFS after excavation can reach to the order of 0.1 MPa, which is greatly higher than that of before. Our preliminary results are useful for optimizing the reinforcement structure during the steep slope stabilization engineering.展开更多
Nonlinear force-free magnetic field （NLFFF） extrapolation based on the observed photo- spheric magnetic field is the most important method to obtain the coronal magnetic field nowadays. However, raw photospheric mag...Nonlinear force-free magnetic field （NLFFF） extrapolation based on the observed photo- spheric magnetic field is the most important method to obtain the coronal magnetic field nowadays. However, raw photospheric magnetograms contain magnetic forces and small-scale noises, and fail to be consistent with the force-free assumption of NLFFF models. The procedure for removing the forces and noises in observed data is called preprocessing. In this paper, we extend the preprocessing code of Jiang ＆ Feng to spherical coordinates for a full sphere. We first smooth the observed data with Gaussian smoothing, and then split the smoothed magnetic field into a potential field and a non-potential field. The potential part is computed by a numerical potential field model, and the non-potential part is prepro- cessed using an optimization method to minimize the magnetic forces and magnetic torques. Applying the code to synoptic charts of the vector magnetic field from SDO/HMI, we find it can effectively reduce the noises and forces, and improve the quality of data for a better input which will be used for NLFFF extrapolations applied to the global corona.展开更多
Can earthquakes be predicted？ How should people overcome the difficulties encountered in the study of earthquake prediction？ This issue can take inspiration from the experiences of weather forecast. Although weather...Can earthquakes be predicted？ How should people overcome the difficulties encountered in the study of earthquake prediction？ This issue can take inspiration from the experiences of weather forecast. Although weather forecasting took a period of about half a century to advance from empirical to numerical forecast, it has achieved significant success. A consensus has been reached among the Chinese seismological community that earth- quake prediction must also develop from empirical fore- casting to physical prediction. However, it is seldom mentioned that physical prediction is characterized by quantitatively numerical predictions based on physical laws. This article discusses five key components for numerical earthquake prediction and their current status. We conclude that numerical earthquake prediction should now be put on the planning agenda and its roadmap designed, seismic stations should be deployed and observations made according to the needs of numerical prediction, and theoretical research should be carried out.展开更多
Taiwan is a young orogenic belt with complex spatial distributions of deformation and earthquakes. We have constructed a three-dimensional finite element model to explore how the interplays between lithospheric struc-...Taiwan is a young orogenic belt with complex spatial distributions of deformation and earthquakes. We have constructed a three-dimensional finite element model to explore how the interplays between lithospheric struc- ture and plate boundary processes control the distribution of stress and strain rates in the Taiwan region. The model assumes a liberalized power-law rheology and incorporates main lithospheric structures; the model domain is loaded by the present-day crustal velocity applied at its bound- aries. The model successfully reproduces the main features of the GPS-measured strain rate patterns and the earth- quake-indicated stress states in the Taiwan region. The best fitting model requires the viscosity of the lower crust to be two orders of magnitude lower than that of the upper crust and lithospheric mantle. The calculated deviatoric stress is high in regions of thrust faulting and low in regions of extensional and strike-slip faulting, consistent with the spatial pattern of seismic intensity in Taiwan.展开更多
Integrated diagnosis,treatment and whole-course management model of major depressive disorder(MDD)is an integrated drug-psychological-physical comprehensive treatment model based on rapid biological-psychological-soci...Integrated diagnosis,treatment and whole-course management model of major depressive disorder(MDD)is an integrated drug-psychological-physical comprehensive treatment model based on rapid biological-psychological-social evaluation for treating patients with major depressive disorder.This paper comprehensively evaluates the clinical efficacy and biochemical indexes of patients,and carries out symptom evaluation,problem classification,disease diagnosis and etiological analysis of visitors from the three dimensions about physiology,psychology and society.Then,according to the symptoms and causes of different dimensions,this paper formulates personalized drug,psychological and physical therapy programs,and constantly optimizes and adjusts the treatment plan in the treatment process,so as to cure both the symptoms and the root causes,providing a reliable strategy for the treatment of clinical MDD,and establishing a standardized characteristic model for further promotion and application of this technology.At present,the project has been used in the member units of Taihe Medical Group and Shiyan City and its surrounding areas,the market response is good,and will be gradually promoted to the whole country in the later stage.展开更多
This paper explores the evolution of geoscientific inquiry,tracing the progression from traditional physics-based models to modern data-driven approaches facilitated by significant advancements in artificial intellige...This paper explores the evolution of geoscientific inquiry,tracing the progression from traditional physics-based models to modern data-driven approaches facilitated by significant advancements in artificial intelligence(AI)and data collection techniques.Traditional models,which are grounded in physical and numerical frameworks,provide robust explanations by explicitly reconstructing underlying physical processes.However,their limitations in comprehensively capturing Earth’s complexities and uncertainties pose challenges in optimization and real-world applicability.In contrast,contemporary data-driven models,particularly those utilizing machine learning(ML)and deep learning(DL),leverage extensive geoscience data to glean insights without requiring exhaustive theoretical knowledge.ML techniques have shown promise in addressing Earth science-related questions.Nevertheless,challenges such as data scarcity,computational demands,data privacy concerns,and the“black-box”nature of AI models hinder their seamless integration into geoscience.The integration of physics-based and data-driven methodologies into hybrid models presents an alternative paradigm.These models,which incorporate domain knowledge to guide AI methodologies,demonstrate enhanced efficiency and performance with reduced training data requirements.This review provides a comprehensive overview of geoscientific research paradigms,emphasizing untapped opportunities at the intersection of advanced AI techniques and geoscience.It examines major methodologies,showcases advances in large-scale models,and discusses the challenges and prospects that will shape the future landscape of AI in geoscience.The paper outlines a dynamic field ripe with possibilities,poised to unlock new understandings of Earth’s complexities and further advance geoscience exploration.展开更多
A mantle thermal plume may be tilted,deflected,or even split-up by mantle lateral flows(mantle wind)during its ascent,which in turn changes the spatial distribution of various geological-magmatic responses,such as mag...A mantle thermal plume may be tilted,deflected,or even split-up by mantle lateral flows(mantle wind)during its ascent,which in turn changes the spatial distribution of various geological-magmatic responses,such as magmatic activity in the overriding plate and hotspot tracks on the surface,affecting the reliability of the constraints on absolute plate motion history.Previous research on tilted mantle plumes has focused mainly on the lower/whole mantle regions.Whether mantle plumes formed in whole/layered mantle convection suffer lateral tilt in the upper mantle,and how this affects the magmatic activity along the surface hotspot track as well as the plume-related tectonic processes,are important scientific issues in mantle thermalplume dynamics and plate tectonics theory.This study introduces a thermal Stokes-fluid-dynamics numerical model(in ASPECT software)and pyrolite parameters constrained by mineral physics data,and quantitatively analyzes the tilted/deflected morphology of upper-mantle plumes and the concomitant surface-hotspot location-evolution characteristics under the combined effects of overriding-plate-motion driven flow(Couette)and upper mantle counter-flow(Poiseuille).We find that this composite upper-mantle wind can lead to(1)Plume head-and-upper-conduit horizontal motion in the opposite direction of the overriding plate motion and also with respect to the conduit roots,such that the magmatic spacing is increased;(2)Near-periodic split-up and ascent of a laterally-moving plume conduit,whose split-up/ascent period depends mainly on the thermo-chemical buoyancy of the plume itself;and(3)Under specific conditions of thermo-chemical buoyancy of a main“parent”plume interacting with upper mantle winds,two secondary“child”plumes hundreds of kilometers apart can sprout and ascend sequentially/subsimultaneously through the upper mantle in a very short period of time(2–4 Myr).The resulting oscillating/jumping behavior of hotspot locations along the overriding plate motion direction can be used to explain the observations on some of Earth's igneous provinces and hotspot tracks(for example,the Kerguelen hotspot)and related-tectonics,that:(i)younger hotspot-magmatictectonic regions can superimpose-to and situate-amidst older ones(surface-hotspot-motion or plume-deflection distances greater than overriding-plate-motion distances,with magmatism separated closely in space but largely in time),and(ii)plume-related magmatism can be widely separated in space but closely in time or age(near-simultaneous ascent of two distant“child”plumes from the same“parent”mantle-plume conduit).Our study suggests that the complex dynamic environment within the upper mantle should be considered when constraining absolute plate motions by the moving-hotspot-reference-frame,especially when these hotspots are located near mid-ocean ridges and/or subduction zones.展开更多
The Xianshuihe fault is a major tectonic boundary between the Sichuan-Yunnan rhombic and Bayanhar blocks in Southwest China.With an average left-lateral strike-slip movement of 10–15 mm/yr,it is a fast-moving strike-...The Xianshuihe fault is a major tectonic boundary between the Sichuan-Yunnan rhombic and Bayanhar blocks in Southwest China.With an average left-lateral strike-slip movement of 10–15 mm/yr,it is a fast-moving strike-slip continental fault.On September 5,2022,the Ms6.8 Luding earthquake occurred along the Moxi segment of the Xianshuihe fault,reaching a maximum intensity of IX and resulting in a significant number of casualties and severe property damage.This earthquake broke the long-standing seismic quiescence of the Xianshuihe fault,which lasted for more than 40 years,and was followed by a significant number of aftershocks.An outstanding question is how the behavior of the Xianshuihe fault and major earthquakes changed following this mainshock.In this study,we examined the changes in regional seismicity following the Luding earthquake and identified the potential for future strong earthquakes along the Xianshuihe fault.We used a finite element numerical method to simulate the environment of the seismogenic fault and its adjacent areas.In addition,we used the coseismic slip model of the Luding earthquake with the split-node method to calculate how the stress and strain fields in the surrounding area were affected by the2022 mainshock.Coulomb stress changes were resolved in the main faults,and the seismicity of adjacent faults was analyzed in conjunction with the observed seismic data.The results indicate that regional tectonic movement primarily occurred to the southeast along the Moxi segment.The stress field is approximately north-south in tension and east-west in compression.Variation in the stress field in the epicentral region of the Luding earthquake exceeded 1 MPa.The maximum displacement of the coseismic deformation field was concentrated between Moxi town and Tuanjie village,and the Coulomb stress of the fault zone in this region experienced the largest decrease.However,the b-value of the Gutenberg-Richter magnitude-frequency relationship at the epicenter and the surrounding area exhibited an abnormal pattern of decrease-decrease-increase,indicating that the regional stress may not be fully released.This earthquake increased the Coulomb stress in other segments of the Xianshuihe,Anninghe,and Daliangshan faults,whereas the Coulomb stress in the Longmenshan and Xiaojinhe fault zones decreased.In addition,it triggered a series of normal-fault,moderate-sized earthquakes in nearby areas.The Dagangshan reservoir,located~20 km from the epicenter of the Luding earthquake,received an increase of~5.3 MPa in the tensile stress along the NWW-SEE direction.The Xiluodu Reservoir,located approximately 225 km from the epicenter,was less affected by this earthquake,and the seismic activity near the reservoir remained relatively unchanged.In this study,post-earthquake seismicity in the vicinity of the Ms6.8 Luding earthquake was analyzed and predicted by numerical simulation,providing a scientific basis for earthquake prediction and disaster reduction.展开更多
1.Introduction.On November 23,2017,an M_(S)5.0 earthquake occurred in Wulong,Chongqing,China,resulting in tens of casualties and considerable economic loss.Geologically,the epicenter of this earthquake was located in ...1.Introduction.On November 23,2017,an M_(S)5.0 earthquake occurred in Wulong,Chongqing,China,resulting in tens of casualties and considerable economic loss.Geologically,the epicenter of this earthquake was located in the transition zone from the Central Chongqing Fold Belt to the southeast,characterized by a low tectonic loading rate.展开更多
Background:Liver biopsy for the diagnosis of non-alcoholic steatohepatitis(NASH)is limited by its inherent invasiveness and possible sampling errors.Some studies have shown that cytokeratin-18(CK-18)concentrations may...Background:Liver biopsy for the diagnosis of non-alcoholic steatohepatitis(NASH)is limited by its inherent invasiveness and possible sampling errors.Some studies have shown that cytokeratin-18(CK-18)concentrations may be useful in diagnosing NASH,but results across studies have been inconsistent.We aimed to identify the utility of CK-18 M30 concentrations as an alternative to liver biopsy for non-invasive identification of NASH.Methods:Individual data were collected from 14 registry centers on patients with biopsy-proven non-alcoholic fatty liver disease(NAFLD),and in all patients,circulating CK-18 M30 levels were measured.Individuals with a NAFLD activity score(NAS)≥5 with a score of≥1 for each of steatosis,ballooning,and lobular inflammation were diagnosed as having definite NASH;individuals with a NAS≤2 and no fibrosis were diagnosed as having non-alcoholic fatty liver(NAFL).Results:A total of 2571 participants were screened,and 1008(153 with NAFL and 855 with NASH)were finally enrolled.Median CK-18 M30 levels were higher in patients with NASH than in those with NAFL(mean difference 177 U/L;standardized mean difference[SMD]:0.87[0.69–1.04]).There was an interaction between CK-18 M30 levels and serum alanine aminotransferase,body mass index(BMI),and hypertension(P<0.001,P=0.026 and P=0.049,respectively).CK-18 M30 levels were positively associated with histological NAS in most centers.The area under the receiver operating characteristics(AUROC)for NASH was 0.750(95%confidence intervals:0.714–0.787),and CK-18 M30 at Youden’s index maximum was 275.7 U/L.Both sensitivity(55%[52%–59%])and positive predictive value(59%)were not ideal.Conclusion:This large multicenter registry study shows that CK-18 M30 measurement in isolation is of limited value for non-invasively diagnosing NASH.展开更多
China has planned and built several world-class cascade high dams in Jinsha River,Dadu River,Lancang River,and Yarlung Zangbo River.The complex geological conditions in the reservoir area and numerous large-scale land...China has planned and built several world-class cascade high dams in Jinsha River,Dadu River,Lancang River,and Yarlung Zangbo River.The complex geological conditions in the reservoir area and numerous large-scale landslide bodies make the potential disaster risk of overflowing and cascade dam failure caused by landslide-generated tsunami under increasing severe situations.However,the study on describing and predicting the complex dynamic processes of generation,propagation,overflowing,wave setup,and the interaction between tsunami and lakeshore has not been systematically carried out.Based on the high-order Boussinesq-type equations,the development of the dynamic system of tsunamis in lakes coupled with the landslide process is realized using the finite volume method in this paper.To verify the accuracy and reliability of the study,the Xiluodu Reservoir is selected as the object to simulate the potential landslide-generated tsunamis.The factors such as the generation and propagation of tsunamis,dam overflowing,and wave setup in the downstream river are quantitatively evaluated and analyzed.The constructed landslide with a total volume of 24×10^(6)m^(3)generates a near-field wave amplitude of about 28 m.The maximum wave run-up height is about 95 m,the volume of the dam overflowing water up to 2.13×10^(6)m^(3),and the maximum wave height above the dam crest presents an M-shaped distribution.This LGWs event raises the downstream water level by nearly 40 m.The results show that the risk of landslide-generated tsunamis in the reservoir area in China cannot be ignored.The developed Boussinesq-type equations coupled with the landslide dynamics can simulate the whole process of generation,propagation,runup,and estimating the overflowing water volume of the tsunamis in the lake,laying a foundation for the quantitative risk assessment of tsunamis in lakes of high cascade dams in China.展开更多
Background and Aims:We compared lung function parameters in nonalcoholic fatty liver disease(NAFLD)and metabolic dysfunction-associated fatty liver disease(MAFLD),and examined the association between lung function par...Background and Aims:We compared lung function parameters in nonalcoholic fatty liver disease(NAFLD)and metabolic dysfunction-associated fatty liver disease(MAFLD),and examined the association between lung function parameters and fibrosis severity in MAFLD.Methods:In this cross-sectional study,we randomly recruited 2,543 middle-aged individuals from 25 communities across four cities in China during 2016 and 2020.All participants received a health check-up including measurement of anthropometric parameters,biochemical variables,liver ultrasonography,and spirometry.The severity of liver disease was assessed by the fibrosis(FIB)-4 score.Results:The prevalence of MAFLD was 20.4%(n=519)and that of NAFLD was 18.4%(n=469).After adjusting for age,sex,adiposity measures,smoking status,and significant alco-hol intake,subjects with MAFLD had a significantly lower predicted forced vital capacity(FVC,88.27±17.60%vs.90.82±16.85%,p<0.05)and lower 1 s forced expiratory volume(FEV1,79.89±17.34 vs.83.02±16.66%,p<0.05)than those with NAFLD.MAFLD with an increased FIB-4 score was significantly associated with decreased lung function.For each 1-point increase in FIB-4,FVC was diminished by 0.507(95%CI:-0.840,-0.173,p=0.003),and FEV1 was diminished by 0.439(95%CI:-0.739,-0.140,p=0.004).The results remained unchanged when the statistical analyses was performed separately for men and women.Conclusions:MAFLD was significantly asso-ciated with a greater impairment of lung function param-eters than NAFLD.展开更多
A three-dimensional full-Stokes computational model is considered for determining the dynamics,temperature,and thickness of ice sheets.The governing thermomechanical equations consist of the three-dimensional full-S...A three-dimensional full-Stokes computational model is considered for determining the dynamics,temperature,and thickness of ice sheets.The governing thermomechanical equations consist of the three-dimensional full-Stokes system with nonlinear rheology for the momentum,an advective-diffusion energy equation for temperature evolution,and a mass conservation equation for ice-thickness changes.Here,we discuss the variable resolution meshes,the finite element discretizations,and the parallel algorithms employed by the model components.The solvers are integrated through a well-designed coupler for the exchange of parametric data between components.The discretization utilizes high-quality,variable-resolution centroidal Voronoi Delaunay triangulation meshing and existing parallel solvers.We demonstrate the gridding technology,discretization schemes,and the efficiency and scalability of the parallel solvers through computational experiments using both simplified geometries arising from benchmark test problems and a realistic Greenland ice sheet geometry.展开更多
Contact electrification-activated triboelectric potential offers an efficient route to tuning the transport properties in semiconductor devices through electrolyte dielectrics,i.e.,triboiontronics.Organic electrochemi...Contact electrification-activated triboelectric potential offers an efficient route to tuning the transport properties in semiconductor devices through electrolyte dielectrics,i.e.,triboiontronics.Organic electrochemical transistors(OECTs)make more effective use of ion injection in the electrolyte dielectrics by changing the doping state of the semiconductor channel.However,the mainstream flexible/wearable electronics and OECT-based devices are usually modulated by electrical signals and constructed in conventional geometry,which lack direct and efficient interaction between the external environment and functional electronic devices.Here,we demonstrate a fiber-shaped triboiontronic electrochemical transistor with good electrical performances,including a current on/off ratio as high as≈1286 with off-current at~nA level,the average threshold displacements(D_(th))of 0.3 mm,the subthreshold swing corresponding to displacement(SS_(D))at 1.6 mm/dec,and excellent flexibility and durability.The proposed triboiontronic electrochemical transistor has great potential to be used in flexible,functional,and smart self-powered electronic textile.展开更多
The Accelerated Hermitian/skew-Hermitian type Richardson(AHSR)iteration methods are presented for solving non-Hermitian positive definite linear systems with three schemes,by using Anderson mixing.The upper bounds of ...The Accelerated Hermitian/skew-Hermitian type Richardson(AHSR)iteration methods are presented for solving non-Hermitian positive definite linear systems with three schemes,by using Anderson mixing.The upper bounds of spectral radii of iteration matrices are studied,and then the convergence theories of the AHSR iteration methods are established.Furthermore,the optimal iteration parameters are provided,which can be computed exactly.In addition,the application to the model convection-diffusion equation is depicted and numerical experiments are conducted to exhibit the effectiveness and confirm the theoretical analysis of the AHSR iteration methods.展开更多
A series of large strike-slip and thrust faults have developed in the northeastern margin of the Tibetan Plateau since the Late Cenozoic,with strong and active tectonic activity and frequent occurrences of large earth...A series of large strike-slip and thrust faults have developed in the northeastern margin of the Tibetan Plateau since the Late Cenozoic,with strong and active tectonic activity and frequent occurrences of large earthquakes.Modulation of regional tectonic stress distribution,strain fields,and seismic hazards has not been well studied.This study introduces a three-dimensional viscoelastic finite element numerical model to calculate crustal stress and strain rate fields under current tectonic loading.The preliminary results show that the direction of the horizontal principal compressive stress rate and compressive horizontal principal strain rate in the northeastern margin of the Tibetan Plateau rotate clockwise as a whole,and this rotation is more significant in the southeast direction because of the block of the Alxa and the Ordos blocks.The NE-SW horizontal principal compressive stress rate and SE horizontal tensile stress rate dominate the entire study region.The maximum value of the horizontal principal compressive strain rate at a depth of 0 km in the model is approximately 4×10^(-8)yr^(-1)near the East Kunlun fault and is smaller in the stable Alxa and Ordos blocks at approximately 1×10^(-8)yr^(-1).The calculated regional stress state is in good agreement with the actual focal mechanism solution,indicating that strike-slip and thrust stress fields dominate the northeastern margin of the Tibetan Plateau.The Altyn Tagh,East Kunlun,and Haiyuan faults demonstrate that the maximum shear strain rate gradually decreases eastward,and the decrease in the maximum shear strain rate value is absorbed by orogenic uplift and crustal shortening at its boundaries.The western section of the Altyn Tagh fault,west-to-middle sections of the East Kunlun fault,and west-to-middle sections of the Haiyuan fault will have high seismic hazards in the future.展开更多
Under the shadow of the far-field effect of the India-Eurasia collision,the Tianshan orogenic belt underwent tectonic re-activation in the Cenozoic,accompanied by strong tectonic deformation and frequent large earthqu...Under the shadow of the far-field effect of the India-Eurasia collision,the Tianshan orogenic belt underwent tectonic re-activation in the Cenozoic,accompanied by strong tectonic deformation and frequent large earthquakes.Bounded by two rigid cratonic blocks located in its north and south,a series of marginal foreland fold-and-thrust belts are developed within the Tianshan orogenic belt and continue to develop to the bilateral pull-apart basins.Meanwhile,the faults in the orogenic belt are reactivated.The deformation caused by thrust-related structure accounts for larger than 50%of the total convergence of the Tianshan Mountains,which results in the most active structure with large earthquakes in the Tianshan area.Therefore,it is of great significance to study the dynamic process of the newly generated and reactivated thrust-nappe structures in Tianshan orogen via numerical modeling.This paper selects a classical cross-section profile in the western segment of the Southwest Tianshan Mountains,which contains the Kalpin-Maidan-Nalati-Kemin fault system from the south to the north.We attempt to establish a two-dimensional plane strain,viscoelastic finite element model,by treating the regional faults as a whole fault system and considering the topography,fault geometry,and GPS data.The displacement and stress fields of the model are retrieved,the short-term cumulative deformation field of the overall fault system is analyzed,and the rate of Coulomb failure stress change of each fault is also considered.The results show that the deformation is concentrated in the middle and southern parts of the Southwest Tianshan Mountains.In contrast,the deformation of the Kemin fault in the north is relatively small.According to the Coulomb failure stress changes of these four faults and the historical earthquake catalog,the potential seismicity of each fault is qualitatively analyzed.Our preliminary results suggest that the possibility of large earthquake occurrence is higher in the Kalpin fault,Maidan fault,and Nalati fault but lower in the Kemin fault in the near future。展开更多
The crystallization experiment of molten rare earth(RE)slag under different cooling rates was carried out.The characteristics of element migration and phase distribution during RE phase crystallization were studied by...The crystallization experiment of molten rare earth(RE)slag under different cooling rates was carried out.The characteristics of element migration and phase distribution during RE phase crystallization were studied by using different equipment.The experimental results show that there are two RE phases in the RE slag,namely(Ca,Ce,La)_(5)(SiO_(4))6F and(Ca,Ce,La,Mg)_(3)(Ti,Al,Nb)_(2)O_(7).During the cooling crystallization process of molten RE slag,Ca and P elements in the RE phase of(Ca,Ce,La)_(5)(SiO_(4))_(6)F migrate from inside to outside,and finally gather at the outer edge of the phase to form phase Ca_(3)(PO4)2.The RE phase(Ca,Ce,La)_(5)(SiO_(4))_(6)F is distributed inside the furnace-cooled slag,and the RE phase(Ca,Ce,-La,Mg)_(3)(Ti,AI,Nb)_(2)O_(7)is distributed in the surface layer of the furnace-cooled slag.And based on the phase distribution characteristics,the central hollowing method is proposed to realize the preliminary enrichment of valuable elements Ti,Nb and RE in RE slag.展开更多
基金supported by the National Natural Science Foundation of China under Grant 41974137.
文摘Magnitude estimation is a critical task in seismology,and conventional methods usually require dense seismic station arrays to provide data with sufficient spatiotemporal distribution.In this context,we propose the Earthquake Graph Network(EQGraphNet)to enhance the performance of single-station magnitude estimation.The backbone of the proposed model consists of eleven convolutional neural network layers and ten RCGL modules,where a RCGL combines a Residual Connection and a Graph convolutional Layer capable of mitigating the over-smoothing problem and simultaneously extracting temporal features of seismic signals.Our work uses the STanford EArthquake Dataset for model training and performance testing.Compared with three existing deep learning models,EQGraphNet demonstrates improved accuracy for both local magnitude and duration magnitude scales.To evaluate the robustness,we add natural background noise to the model input and find that EQGraphNet achieves the best results,particularly for signals with lower signal-to-noise ratios.Additionally,by replacing various network components and comparing their estimation performances,we illustrate the contribution of each part of EQGraphNet,validating the rationality of our approach.We also demonstrate the generalization capability of our model across different earthquakes occurring environments,achieving mean errors of±0.1 units.Furthermore,by demonstrating the effectiveness of deeper architectures,this work encourages further exploration of deeper GNN models for both multi-station and single-station magnitude estimation.
基金supported by Sinoprob-Deep Exploration Program in China sponsored by Ministry of Land and Resources of the People’s Republic of China (No.0819011A90)National Natural Science Foundation of China (No.D0408/4097409)
文摘The distribution of Coulomb failure stress （CFS） change in the steep excavation slope is calculated by finite element method in this paper, and the failure mechanics under different conditions have been investigated. Comparing the CFSs before and after the slope excavation （stress loading and unloading processes）, the dangerous internal zone and the most likely failure external area are attained. Given the shear cracks on the top surface while tensile stress or cracks along the toe of the slope, we analyze the high cutting-angle steep slope in Kaixian county of the Three Gorges Reservoir region. We bring forward that the peak value of CFS after excavation can reach to the order of 0.1 MPa, which is greatly higher than that of before. Our preliminary results are useful for optimizing the reinforcement structure during the steep slope stabilization engineering.
基金supported by the National Natural Science Foundation of China (41604140)the Specialized Research Fund for State Key Laboratories and China Postdoctoral Science Foundation Fund
文摘Nonlinear force-free magnetic field （NLFFF） extrapolation based on the observed photo- spheric magnetic field is the most important method to obtain the coronal magnetic field nowadays. However, raw photospheric magnetograms contain magnetic forces and small-scale noises, and fail to be consistent with the force-free assumption of NLFFF models. The procedure for removing the forces and noises in observed data is called preprocessing. In this paper, we extend the preprocessing code of Jiang ＆ Feng to spherical coordinates for a full sphere. We first smooth the observed data with Gaussian smoothing, and then split the smoothed magnetic field into a potential field and a non-potential field. The potential part is computed by a numerical potential field model, and the non-potential part is prepro- cessed using an optimization method to minimize the magnetic forces and magnetic torques. Applying the code to synoptic charts of the vector magnetic field from SDO/HMI, we find it can effectively reduce the noises and forces, and improve the quality of data for a better input which will be used for NLFFF extrapolations applied to the global corona.
基金supported by the CAS/CAFEA international partnership Program for creative research teams (No.KZZD-EW-TZ-19)China National Science and Technology Support Program ‘‘Practical Techniques for Earthquake Analysis and Prediction Research’’ 2012BAK19B03-5
文摘Can earthquakes be predicted？ How should people overcome the difficulties encountered in the study of earthquake prediction？ This issue can take inspiration from the experiences of weather forecast. Although weather forecasting took a period of about half a century to advance from empirical to numerical forecast, it has achieved significant success. A consensus has been reached among the Chinese seismological community that earth- quake prediction must also develop from empirical fore- casting to physical prediction. However, it is seldom mentioned that physical prediction is characterized by quantitatively numerical predictions based on physical laws. This article discusses five key components for numerical earthquake prediction and their current status. We conclude that numerical earthquake prediction should now be put on the planning agenda and its roadmap designed, seismic stations should be deployed and observations made according to the needs of numerical prediction, and theoretical research should be carried out.
基金supported by the National Natural Science Foundation of China(No.41204066)China Geological Survey(Nos.12120114002101,12120114002401)+1 种基金Deep Exploration in China(SinoProbe-08-01,SinoProbe-07)the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘Taiwan is a young orogenic belt with complex spatial distributions of deformation and earthquakes. We have constructed a three-dimensional finite element model to explore how the interplays between lithospheric struc- ture and plate boundary processes control the distribution of stress and strain rates in the Taiwan region. The model assumes a liberalized power-law rheology and incorporates main lithospheric structures; the model domain is loaded by the present-day crustal velocity applied at its bound- aries. The model successfully reproduces the main features of the GPS-measured strain rate patterns and the earth- quake-indicated stress states in the Taiwan region. The best fitting model requires the viscosity of the lower crust to be two orders of magnitude lower than that of the upper crust and lithospheric mantle. The calculated deviatoric stress is high in regions of thrust faulting and low in regions of extensional and strike-slip faulting, consistent with the spatial pattern of seismic intensity in Taiwan.
基金Supported by Grants from the National Key R&D Program of China (2018YFC1314600)the 2021 Shiyan City Guidance Project (21Y33)
文摘Integrated diagnosis,treatment and whole-course management model of major depressive disorder(MDD)is an integrated drug-psychological-physical comprehensive treatment model based on rapid biological-psychological-social evaluation for treating patients with major depressive disorder.This paper comprehensively evaluates the clinical efficacy and biochemical indexes of patients,and carries out symptom evaluation,problem classification,disease diagnosis and etiological analysis of visitors from the three dimensions about physiology,psychology and society.Then,according to the symptoms and causes of different dimensions,this paper formulates personalized drug,psychological and physical therapy programs,and constantly optimizes and adjusts the treatment plan in the treatment process,so as to cure both the symptoms and the root causes,providing a reliable strategy for the treatment of clinical MDD,and establishing a standardized characteristic model for further promotion and application of this technology.At present,the project has been used in the member units of Taihe Medical Group and Shiyan City and its surrounding areas,the market response is good,and will be gradually promoted to the whole country in the later stage.
基金supported by National Natural Science Foundation of China(T2225019,41925007,62372470,U21A2013,42201415,42022054,42241109,42077156,52121006,42090014,and 42325107)the National Key R&D Programme of China(2022YFF0500)+2 种基金the Youth Innovation Promotion Association CAS(2023112)the Strategic Priority Research Program of CAS(XDA23090303)the RECLAIM Network Plus(EP/W034034/1).
文摘This paper explores the evolution of geoscientific inquiry,tracing the progression from traditional physics-based models to modern data-driven approaches facilitated by significant advancements in artificial intelligence(AI)and data collection techniques.Traditional models,which are grounded in physical and numerical frameworks,provide robust explanations by explicitly reconstructing underlying physical processes.However,their limitations in comprehensively capturing Earth’s complexities and uncertainties pose challenges in optimization and real-world applicability.In contrast,contemporary data-driven models,particularly those utilizing machine learning(ML)and deep learning(DL),leverage extensive geoscience data to glean insights without requiring exhaustive theoretical knowledge.ML techniques have shown promise in addressing Earth science-related questions.Nevertheless,challenges such as data scarcity,computational demands,data privacy concerns,and the“black-box”nature of AI models hinder their seamless integration into geoscience.The integration of physics-based and data-driven methodologies into hybrid models presents an alternative paradigm.These models,which incorporate domain knowledge to guide AI methodologies,demonstrate enhanced efficiency and performance with reduced training data requirements.This review provides a comprehensive overview of geoscientific research paradigms,emphasizing untapped opportunities at the intersection of advanced AI techniques and geoscience.It examines major methodologies,showcases advances in large-scale models,and discusses the challenges and prospects that will shape the future landscape of AI in geoscience.The paper outlines a dynamic field ripe with possibilities,poised to unlock new understandings of Earth’s complexities and further advance geoscience exploration.
基金supported by the National Key Scientific and Technological Infrastructure project“Earth System Science Numerical Simulator Facility”(EarthLab)supported by the National Natural Science Foundation of China(Grant Nos.U2239205,41725017)。
文摘A mantle thermal plume may be tilted,deflected,or even split-up by mantle lateral flows(mantle wind)during its ascent,which in turn changes the spatial distribution of various geological-magmatic responses,such as magmatic activity in the overriding plate and hotspot tracks on the surface,affecting the reliability of the constraints on absolute plate motion history.Previous research on tilted mantle plumes has focused mainly on the lower/whole mantle regions.Whether mantle plumes formed in whole/layered mantle convection suffer lateral tilt in the upper mantle,and how this affects the magmatic activity along the surface hotspot track as well as the plume-related tectonic processes,are important scientific issues in mantle thermalplume dynamics and plate tectonics theory.This study introduces a thermal Stokes-fluid-dynamics numerical model(in ASPECT software)and pyrolite parameters constrained by mineral physics data,and quantitatively analyzes the tilted/deflected morphology of upper-mantle plumes and the concomitant surface-hotspot location-evolution characteristics under the combined effects of overriding-plate-motion driven flow(Couette)and upper mantle counter-flow(Poiseuille).We find that this composite upper-mantle wind can lead to(1)Plume head-and-upper-conduit horizontal motion in the opposite direction of the overriding plate motion and also with respect to the conduit roots,such that the magmatic spacing is increased;(2)Near-periodic split-up and ascent of a laterally-moving plume conduit,whose split-up/ascent period depends mainly on the thermo-chemical buoyancy of the plume itself;and(3)Under specific conditions of thermo-chemical buoyancy of a main“parent”plume interacting with upper mantle winds,two secondary“child”plumes hundreds of kilometers apart can sprout and ascend sequentially/subsimultaneously through the upper mantle in a very short period of time(2–4 Myr).The resulting oscillating/jumping behavior of hotspot locations along the overriding plate motion direction can be used to explain the observations on some of Earth's igneous provinces and hotspot tracks(for example,the Kerguelen hotspot)and related-tectonics,that:(i)younger hotspot-magmatictectonic regions can superimpose-to and situate-amidst older ones(surface-hotspot-motion or plume-deflection distances greater than overriding-plate-motion distances,with magmatism separated closely in space but largely in time),and(ii)plume-related magmatism can be widely separated in space but closely in time or age(near-simultaneous ascent of two distant“child”plumes from the same“parent”mantle-plume conduit).Our study suggests that the complex dynamic environment within the upper mantle should be considered when constraining absolute plate motions by the moving-hotspot-reference-frame,especially when these hotspots are located near mid-ocean ridges and/or subduction zones.
基金supported by the National Key Research and Development Project of China(Grant No.2021YFC3000703-06)the Central Publicinterest Scientific Institution Basal Research Fund(Grant No.CEAIEF20230209)+1 种基金the National Natural Science Foundation of China(Grant Nos.U2239205,41725017,U2039207)partially supported by the National Key Scientific and Technological Infrastructure project“Earth System Science Numerical Simulator Facility(Earth Lab)”。
文摘The Xianshuihe fault is a major tectonic boundary between the Sichuan-Yunnan rhombic and Bayanhar blocks in Southwest China.With an average left-lateral strike-slip movement of 10–15 mm/yr,it is a fast-moving strike-slip continental fault.On September 5,2022,the Ms6.8 Luding earthquake occurred along the Moxi segment of the Xianshuihe fault,reaching a maximum intensity of IX and resulting in a significant number of casualties and severe property damage.This earthquake broke the long-standing seismic quiescence of the Xianshuihe fault,which lasted for more than 40 years,and was followed by a significant number of aftershocks.An outstanding question is how the behavior of the Xianshuihe fault and major earthquakes changed following this mainshock.In this study,we examined the changes in regional seismicity following the Luding earthquake and identified the potential for future strong earthquakes along the Xianshuihe fault.We used a finite element numerical method to simulate the environment of the seismogenic fault and its adjacent areas.In addition,we used the coseismic slip model of the Luding earthquake with the split-node method to calculate how the stress and strain fields in the surrounding area were affected by the2022 mainshock.Coulomb stress changes were resolved in the main faults,and the seismicity of adjacent faults was analyzed in conjunction with the observed seismic data.The results indicate that regional tectonic movement primarily occurred to the southeast along the Moxi segment.The stress field is approximately north-south in tension and east-west in compression.Variation in the stress field in the epicentral region of the Luding earthquake exceeded 1 MPa.The maximum displacement of the coseismic deformation field was concentrated between Moxi town and Tuanjie village,and the Coulomb stress of the fault zone in this region experienced the largest decrease.However,the b-value of the Gutenberg-Richter magnitude-frequency relationship at the epicenter and the surrounding area exhibited an abnormal pattern of decrease-decrease-increase,indicating that the regional stress may not be fully released.This earthquake increased the Coulomb stress in other segments of the Xianshuihe,Anninghe,and Daliangshan faults,whereas the Coulomb stress in the Longmenshan and Xiaojinhe fault zones decreased.In addition,it triggered a series of normal-fault,moderate-sized earthquakes in nearby areas.The Dagangshan reservoir,located~20 km from the epicenter of the Luding earthquake,received an increase of~5.3 MPa in the tensile stress along the NWW-SEE direction.The Xiluodu Reservoir,located approximately 225 km from the epicenter,was less affected by this earthquake,and the seismic activity near the reservoir remained relatively unchanged.In this study,post-earthquake seismicity in the vicinity of the Ms6.8 Luding earthquake was analyzed and predicted by numerical simulation,providing a scientific basis for earthquake prediction and disaster reduction.
基金support provided by the National Major Scientific and Technological Infrastructure Project“Numerical Simulator for Earth System”supported by the National Natural Science Foundation of China(Grant No.U2239205)the Open Fund of the State Key Laboratory of Geodesy and Earth’s Dynamics(Grant No.SKLGED2023-4-2)。
文摘1.Introduction.On November 23,2017,an M_(S)5.0 earthquake occurred in Wulong,Chongqing,China,resulting in tens of casualties and considerable economic loss.Geologically,the epicenter of this earthquake was located in the transition zone from the Central Chongqing Fold Belt to the southeast,characterized by a low tectonic loading rate.
基金supported by grants from the National Natural Science Foundation of China(No.82070588)High-Level Creative Talents from the Department of Public Health in Zhejiang Province(No.S2032102600032)+4 种基金Project of New Century 551 Talent Nurturing in Wenzhou.G.Targher is supported in part by grants from the University School of Medicine of Verona,Verona,ItalyC.D.Byrne is supported in part by the Southampton NIHR Biomedical Research Centre(No.IS-BRC-20004),UK.MEJG are supported by the Robert W.Storr Bequest to the Sydney Medical Foundation,University of Sydneya National Health and Medical Research Council of Australia(NHMRC)Program Grant(No.APP1053206)Project and ideas grants(Nos.APP2001692,APP1107178,and APP1108422).
文摘Background:Liver biopsy for the diagnosis of non-alcoholic steatohepatitis(NASH)is limited by its inherent invasiveness and possible sampling errors.Some studies have shown that cytokeratin-18(CK-18)concentrations may be useful in diagnosing NASH,but results across studies have been inconsistent.We aimed to identify the utility of CK-18 M30 concentrations as an alternative to liver biopsy for non-invasive identification of NASH.Methods:Individual data were collected from 14 registry centers on patients with biopsy-proven non-alcoholic fatty liver disease(NAFLD),and in all patients,circulating CK-18 M30 levels were measured.Individuals with a NAFLD activity score(NAS)≥5 with a score of≥1 for each of steatosis,ballooning,and lobular inflammation were diagnosed as having definite NASH;individuals with a NAS≤2 and no fibrosis were diagnosed as having non-alcoholic fatty liver(NAFL).Results:A total of 2571 participants were screened,and 1008(153 with NAFL and 855 with NASH)were finally enrolled.Median CK-18 M30 levels were higher in patients with NASH than in those with NAFL(mean difference 177 U/L;standardized mean difference[SMD]:0.87[0.69–1.04]).There was an interaction between CK-18 M30 levels and serum alanine aminotransferase,body mass index(BMI),and hypertension(P<0.001,P=0.026 and P=0.049,respectively).CK-18 M30 levels were positively associated with histological NAS in most centers.The area under the receiver operating characteristics(AUROC)for NASH was 0.750(95%confidence intervals:0.714–0.787),and CK-18 M30 at Youden’s index maximum was 275.7 U/L.Both sensitivity(55%[52%–59%])and positive predictive value(59%)were not ideal.Conclusion:This large multicenter registry study shows that CK-18 M30 measurement in isolation is of limited value for non-invasively diagnosing NASH.
基金supported by the National Natural Science Foundation of China(Grant No.41725017)the National Key R&D Program of the Ministry of Science and Technology of China(Grant No.2020YFA0713401)the National Natural Science Foundation of China(Grant No.U1839207)。
文摘China has planned and built several world-class cascade high dams in Jinsha River,Dadu River,Lancang River,and Yarlung Zangbo River.The complex geological conditions in the reservoir area and numerous large-scale landslide bodies make the potential disaster risk of overflowing and cascade dam failure caused by landslide-generated tsunami under increasing severe situations.However,the study on describing and predicting the complex dynamic processes of generation,propagation,overflowing,wave setup,and the interaction between tsunami and lakeshore has not been systematically carried out.Based on the high-order Boussinesq-type equations,the development of the dynamic system of tsunamis in lakes coupled with the landslide process is realized using the finite volume method in this paper.To verify the accuracy and reliability of the study,the Xiluodu Reservoir is selected as the object to simulate the potential landslide-generated tsunamis.The factors such as the generation and propagation of tsunamis,dam overflowing,and wave setup in the downstream river are quantitatively evaluated and analyzed.The constructed landslide with a total volume of 24×10^(6)m^(3)generates a near-field wave amplitude of about 28 m.The maximum wave run-up height is about 95 m,the volume of the dam overflowing water up to 2.13×10^(6)m^(3),and the maximum wave height above the dam crest presents an M-shaped distribution.This LGWs event raises the downstream water level by nearly 40 m.The results show that the risk of landslide-generated tsunamis in the reservoir area in China cannot be ignored.The developed Boussinesq-type equations coupled with the landslide dynamics can simulate the whole process of generation,propagation,runup,and estimating the overflowing water volume of the tsunamis in the lake,laying a foundation for the quantitative risk assessment of tsunamis in lakes of high cascade dams in China.
基金This study was supported by the National Key Research and Development Program of China(No:2016YFC1304000)National Natural Science Foundation of China(82000690)+2 种基金High Level Creative Talents from Department of Public Health in Zhejiang Province,and the Key Research and Development Program of Zhejiang Province(No:2019C03030)GT was supported in part by grants from the University School of Medicine of Verona,Verona,ItalyCDB was supported in part by the Southampton National Institute for Health Research Biomedical Research Center.
文摘Background and Aims:We compared lung function parameters in nonalcoholic fatty liver disease(NAFLD)and metabolic dysfunction-associated fatty liver disease(MAFLD),and examined the association between lung function parameters and fibrosis severity in MAFLD.Methods:In this cross-sectional study,we randomly recruited 2,543 middle-aged individuals from 25 communities across four cities in China during 2016 and 2020.All participants received a health check-up including measurement of anthropometric parameters,biochemical variables,liver ultrasonography,and spirometry.The severity of liver disease was assessed by the fibrosis(FIB)-4 score.Results:The prevalence of MAFLD was 20.4%(n=519)and that of NAFLD was 18.4%(n=469).After adjusting for age,sex,adiposity measures,smoking status,and significant alco-hol intake,subjects with MAFLD had a significantly lower predicted forced vital capacity(FVC,88.27±17.60%vs.90.82±16.85%,p<0.05)and lower 1 s forced expiratory volume(FEV1,79.89±17.34 vs.83.02±16.66%,p<0.05)than those with NAFLD.MAFLD with an increased FIB-4 score was significantly associated with decreased lung function.For each 1-point increase in FIB-4,FVC was diminished by 0.507(95%CI:-0.840,-0.173,p=0.003),and FEV1 was diminished by 0.439(95%CI:-0.739,-0.140,p=0.004).The results remained unchanged when the statistical analyses was performed separately for men and women.Conclusions:MAFLD was significantly asso-ciated with a greater impairment of lung function param-eters than NAFLD.
基金the US DOE Office of Science’s Climate Change Prediction Program through DE-FG02-07ER64431,DE-FG02-07ER64432 and DOE 07SCPF152the US National Science Foundation under grant number DMS-0913491.
文摘A three-dimensional full-Stokes computational model is considered for determining the dynamics,temperature,and thickness of ice sheets.The governing thermomechanical equations consist of the three-dimensional full-Stokes system with nonlinear rheology for the momentum,an advective-diffusion energy equation for temperature evolution,and a mass conservation equation for ice-thickness changes.Here,we discuss the variable resolution meshes,the finite element discretizations,and the parallel algorithms employed by the model components.The solvers are integrated through a well-designed coupler for the exchange of parametric data between components.The discretization utilizes high-quality,variable-resolution centroidal Voronoi Delaunay triangulation meshing and existing parallel solvers.We demonstrate the gridding technology,discretization schemes,and the efficiency and scalability of the parallel solvers through computational experiments using both simplified geometries arising from benchmark test problems and a realistic Greenland ice sheet geometry.
基金supported by the National Key Research and Development Program of China(2016YFA0202703,2016YFA0202701)the Fundamental Research Funds for the Central Universities(E0EG6801X2)+2 种基金the National Natural Science Foundation of China(52073031,51605034,and 51711540300)the Beijing Nova Program(Z191100001119047)the“Hundred Talents Program”of the Chinese Academy of Science.
文摘Contact electrification-activated triboelectric potential offers an efficient route to tuning the transport properties in semiconductor devices through electrolyte dielectrics,i.e.,triboiontronics.Organic electrochemical transistors(OECTs)make more effective use of ion injection in the electrolyte dielectrics by changing the doping state of the semiconductor channel.However,the mainstream flexible/wearable electronics and OECT-based devices are usually modulated by electrical signals and constructed in conventional geometry,which lack direct and efficient interaction between the external environment and functional electronic devices.Here,we demonstrate a fiber-shaped triboiontronic electrochemical transistor with good electrical performances,including a current on/off ratio as high as≈1286 with off-current at~nA level,the average threshold displacements(D_(th))of 0.3 mm,the subthreshold swing corresponding to displacement(SS_(D))at 1.6 mm/dec,and excellent flexibility and durability.The proposed triboiontronic electrochemical transistor has great potential to be used in flexible,functional,and smart self-powered electronic textile.
基金Supported by National Science Foundation of China(Grant Nos.41725017 and 42004085)Guangdong Basic and Applied Basic Research Foundation(Grant No.2019A1515110184)the National Key R&D Program of the Ministry of Science and Technology of China(Grant Nos.2020YFA0713400 and 2020YFA0713401)。
文摘The Accelerated Hermitian/skew-Hermitian type Richardson(AHSR)iteration methods are presented for solving non-Hermitian positive definite linear systems with three schemes,by using Anderson mixing.The upper bounds of spectral radii of iteration matrices are studied,and then the convergence theories of the AHSR iteration methods are established.Furthermore,the optimal iteration parameters are provided,which can be computed exactly.In addition,the application to the model convection-diffusion equation is depicted and numerical experiments are conducted to exhibit the effectiveness and confirm the theoretical analysis of the AHSR iteration methods.
基金supported by the National Natural Science Foundation of China for Distinguished Young Scholars(Grant Nos.U2239205,41725017)the National Key Scientific and Technological Infrastructure Project。
文摘A series of large strike-slip and thrust faults have developed in the northeastern margin of the Tibetan Plateau since the Late Cenozoic,with strong and active tectonic activity and frequent occurrences of large earthquakes.Modulation of regional tectonic stress distribution,strain fields,and seismic hazards has not been well studied.This study introduces a three-dimensional viscoelastic finite element numerical model to calculate crustal stress and strain rate fields under current tectonic loading.The preliminary results show that the direction of the horizontal principal compressive stress rate and compressive horizontal principal strain rate in the northeastern margin of the Tibetan Plateau rotate clockwise as a whole,and this rotation is more significant in the southeast direction because of the block of the Alxa and the Ordos blocks.The NE-SW horizontal principal compressive stress rate and SE horizontal tensile stress rate dominate the entire study region.The maximum value of the horizontal principal compressive strain rate at a depth of 0 km in the model is approximately 4×10^(-8)yr^(-1)near the East Kunlun fault and is smaller in the stable Alxa and Ordos blocks at approximately 1×10^(-8)yr^(-1).The calculated regional stress state is in good agreement with the actual focal mechanism solution,indicating that strike-slip and thrust stress fields dominate the northeastern margin of the Tibetan Plateau.The Altyn Tagh,East Kunlun,and Haiyuan faults demonstrate that the maximum shear strain rate gradually decreases eastward,and the decrease in the maximum shear strain rate value is absorbed by orogenic uplift and crustal shortening at its boundaries.The western section of the Altyn Tagh fault,west-to-middle sections of the East Kunlun fault,and west-to-middle sections of the Haiyuan fault will have high seismic hazards in the future.
基金This work was supported by the National Science Foundation for Distinguished Young Scholars(Grant No.41725017)the National Key R&D Program of China(Grant No.2020YFA0713401).
文摘Under the shadow of the far-field effect of the India-Eurasia collision,the Tianshan orogenic belt underwent tectonic re-activation in the Cenozoic,accompanied by strong tectonic deformation and frequent large earthquakes.Bounded by two rigid cratonic blocks located in its north and south,a series of marginal foreland fold-and-thrust belts are developed within the Tianshan orogenic belt and continue to develop to the bilateral pull-apart basins.Meanwhile,the faults in the orogenic belt are reactivated.The deformation caused by thrust-related structure accounts for larger than 50%of the total convergence of the Tianshan Mountains,which results in the most active structure with large earthquakes in the Tianshan area.Therefore,it is of great significance to study the dynamic process of the newly generated and reactivated thrust-nappe structures in Tianshan orogen via numerical modeling.This paper selects a classical cross-section profile in the western segment of the Southwest Tianshan Mountains,which contains the Kalpin-Maidan-Nalati-Kemin fault system from the south to the north.We attempt to establish a two-dimensional plane strain,viscoelastic finite element model,by treating the regional faults as a whole fault system and considering the topography,fault geometry,and GPS data.The displacement and stress fields of the model are retrieved,the short-term cumulative deformation field of the overall fault system is analyzed,and the rate of Coulomb failure stress change of each fault is also considered.The results show that the deformation is concentrated in the middle and southern parts of the Southwest Tianshan Mountains.In contrast,the deformation of the Kemin fault in the north is relatively small.According to the Coulomb failure stress changes of these four faults and the historical earthquake catalog,the potential seismicity of each fault is qualitatively analyzed.Our preliminary results suggest that the possibility of large earthquake occurrence is higher in the Kalpin fault,Maidan fault,and Nalati fault but lower in the Kemin fault in the near future。
基金supported by the National Natural Science Foundation of China(51874029)。
文摘The crystallization experiment of molten rare earth(RE)slag under different cooling rates was carried out.The characteristics of element migration and phase distribution during RE phase crystallization were studied by using different equipment.The experimental results show that there are two RE phases in the RE slag,namely(Ca,Ce,La)_(5)(SiO_(4))6F and(Ca,Ce,La,Mg)_(3)(Ti,Al,Nb)_(2)O_(7).During the cooling crystallization process of molten RE slag,Ca and P elements in the RE phase of(Ca,Ce,La)_(5)(SiO_(4))_(6)F migrate from inside to outside,and finally gather at the outer edge of the phase to form phase Ca_(3)(PO4)2.The RE phase(Ca,Ce,La)_(5)(SiO_(4))_(6)F is distributed inside the furnace-cooled slag,and the RE phase(Ca,Ce,-La,Mg)_(3)(Ti,AI,Nb)_(2)O_(7)is distributed in the surface layer of the furnace-cooled slag.And based on the phase distribution characteristics,the central hollowing method is proposed to realize the preliminary enrichment of valuable elements Ti,Nb and RE in RE slag.
