New information and communication technologies have led to the emergence of new techniques in our daily lives. Indeed, in topography, a lightning development of new techniques and new devices has been noticed. This de...New information and communication technologies have led to the emergence of new techniques in our daily lives. Indeed, in topography, a lightning development of new techniques and new devices has been noticed. This development has given rise to a multitude of choices of devices and various classes of precision. This implies that the decision-makers have to study the adequate equipment and the appropriate technique according to the topographic task to be realized. The objective is not to compare GNSS and topographic techniques, but to point out the contribution of the Global Navigation Satelite System (GNSS) techniques of topographic work. Thus, a theoretical study with a critical eye on the scientific principle of calculating the third topographic dimension followed by a leveling campaign, Real Time Kinematic (RTK) surveys will be used in order to be able to compare and interpret the result from these campaigns. The study of the difference resulting from the practical campaigns will allow us to identify the contribution of GNSS technology.展开更多
The investigations of physical attributes of oceans,including parameters such as heat flow and bathymetry,have garnered substantial attention and are particularly valuable for examining Earth’s thermal structures and...The investigations of physical attributes of oceans,including parameters such as heat flow and bathymetry,have garnered substantial attention and are particularly valuable for examining Earth’s thermal structures and dynamic processes.Nevertheless,classical plate cooling models exhibit disparities when predicting observed heat flow and seafloor depth for extremely young and old lithospheres.Furthermore,a comprehensive analysis of global heat flow predictions and regional ocean heat flow or bathymetry data with physical models has been lacking.In this study,we employed power-law models derived from the singularity theory of fractal density to meticulously fit the latest ocean heat flow and bathymetry.Notably,power-law models offer distinct advantages over traditional plate cooling models,showcasing robust self-similarity,scale invariance,or scaling properties,and providing a better fit to observed data.The outcomes of our singularity analysis concerning heat flow and bathymetry across diverse oceanic regions exhibit a degree of consistency with the global ocean spreading rate model.In addition,we applied the similarity method to predict a higher resolution(0.1°×0.1°)global heat flow map based on the most recent heat flow data and geological/geophysical observables refined through linear correlation analysis.Regions displaying significant disparities between predicted and observed heat flow are closely linked to hydrothermal vent fields and active structures.Finally,combining the actual bathymetry and predicted heat flow with the power-law models allows for the quantitative and comprehensive detection of anomalous regions of ocean subsidence and heat flow,which deviate from traditional plate cooling models.The anomalous regions of subsidence and heat flow show different degrees of anisotropy,providing new ideas and clues for further analysis of ocean topography or hydrothermal circulation of mid-ocean ridges.展开更多
Traumatic injuries to the central nervous system(CNS) result in disruption of the intricate network of axons which connect functionally related neurons that are widely distributed throughout the brain and spinal cord....Traumatic injuries to the central nervous system(CNS) result in disruption of the intricate network of axons which connect functionally related neurons that are widely distributed throughout the brain and spinal cord.Under normal conditions,maintenance of this complex system is structurally and functionally supported by astrocytes (ACs)and other glial cells,the processes of which form a framework surrounding neuronal cell bodies,dendrites,axons,and synapses.展开更多
The Hengduan Mountains,situated on the southeastern edge of the Qinghai-Tibet Plateau,are the longest and widest north-south-oriented mountain range in China,exerting a significant influence on the ecological and geog...The Hengduan Mountains,situated on the southeastern edge of the Qinghai-Tibet Plateau,are the longest and widest north-south-oriented mountain range in China,exerting a significant influence on the ecological and geographical pattern.Understanding the topographic and geomorphological characteristics of the Hengduan Mountains is fundamental and crucial for research in related fields such as ecology,geography,and sustainability.In this study,Digital Elevation Model(DEM)data were utilized to extract and analyze the topography and geomorphology(TG)pattern.TG maps have been developed to quantitatively classify the TG types in the Hengduan Mountains by combining the five factors of elevation,slope,aspect,relief and landform.The spatial distribution and quantitative characteristics of these factors were mapped and investigated using geographic information systems.The results revealed that:(1)The Hengduan Mountains exhibit an elongated north-south distribution,with an average elevation of approximately 3746 m,an average slope of around 25°,and an average relief of about 266 m.(2)The Hengduan Mountains display significant elevation differences,with an overall high elevation,characterized by a trend of lower elevation in the east and higher elevation in the west,as well as irregular orientations of various aspects.(3)The 19 landform types were identified,the landform types of the Hengduan Mountains are primarily composed of low-relief high-mountains(42.0618%),low-relief mid-mountains(22.4624%),and high-elevation hills(20.5839%).The results of the study can provide data and information support for the ecology,environmental protection and sustainable development of the Hengduan Mountains.展开更多
Progressive modifications in submarine topography and shorelines drastically affect tidal dynamics in bays.This study examines the influence of topographic slope,bay length,and driving forces on tidal currents followi...Progressive modifications in submarine topography and shorelines drastically affect tidal dynamics in bays.This study examines the influence of topographic slope,bay length,and driving forces on tidal currents following land reclamation.Tidal equa-tions are analytically solved using infinite series,deriving expressions for tidal levels and currents in narrow bays with varying topog-raphy.Tidal levels,influenced by topographic variations,are characterized by amplitude and phase lag of their complex amplitude.These levels demonstrate high sensitivity to longitudinal slope variations but remain relatively stable under lateral slope changes.Un-der constant topographic slopes,even minor changes in bay length can drastically modify amplitude and phase lag,highlighting the sensitivity of tidal dynamics to geometric alterations.Tidal velocity notably increases with steeper longitudinal slopes and modestly rises with elevated lateral slopes.However,changes in longitudinal and lateral slopes do not considerably alter flow patterns.While external forces predominantly regulate tidal velocity with negligible effects on flow patterns,endogenous resistance influences veloci-ty but minimally impacts flow structure.These findings enhance the understanding of tidal responses to geometric and topographic changes,providing valuable guidance for land reclamation projects and coastal management strategies.展开更多
AIM:To evaluate the potential of artificial intelligence(AI)for automating corneal topography interpretation in orthokeratology patients,aiming to enhance diagnostic precision,efficiency,and clinical decision-making i...AIM:To evaluate the potential of artificial intelligence(AI)for automating corneal topography interpretation in orthokeratology patients,aiming to enhance diagnostic precision,efficiency,and clinical decision-making in myopia management.METHODS:The 1469 corneal topography images from 582 eyes of 326 myopic children treated with orthokeratology lenses over 47mo were collected.Each sample was categorized by decentration,treatment zone size,shape variation,and eye laterality.A multi-task AI model was developed to predict these parameters,with performance measured using area under curve(AUC),accuracy,and F1 scores.We compared AI-only,humanonly,and combined Human+AI approaches on a subset of 100 images.External validation with images from additional hospitals tested model generalizability.RESULTS:The model achieved high accuracy in eyeside prediction(AUC 0.95)and AUC values of 0.52-0.74 for decentration,treatment zone,and shape variation tasks.The combined Human+AI method outperformed AI-only and human-only approaches,achieving the highest accuracy(up to 87%)and fastest processing time(80ms).External validation confirmed robust performance in simple tasks,though accuracy was lower for complex classifications due to imaging variations.CONCLUSION:AI provides efficient routine corneal topography assessments,while complex cases benefit most from a Human+AI approach,particularly in scenarios requiring nuanced clinical interpretation.The model currently functions as an assistive tool.展开更多
Fog is a highly complex weather phenomenon influenced by numerous factors.This study investigated the impact of the Changbai Mountains’topography on the formation and development of spring fog in the Bohai Sea.From 1...Fog is a highly complex weather phenomenon influenced by numerous factors.This study investigated the impact of the Changbai Mountains’topography on the formation and development of spring fog in the Bohai Sea.From 12 to 14 May 2021,the Bohai region experienced a sea fog event.Utilizing Himawari-8 satellite data,ERA5 reanalysis dataset,land and sea station observations,the WRF model,a topography sensitivity experiment,and backward trajectory tracking,the influence of the Changbai Mountains’topography on the evolution of this sea fog event was assessed.Results indicated that the Changbai Mountains’topography significantly impacted the propagation and concentration of the sea fog through dual effects—namely,the Venturi Effect and Foehn Clearance Effect.Comparative simulations incorporating and excluding the Changbai Mountains revealed that its topography favored weak convergence(Venturi Effect)of low-level airflow over the Bohai Sea induced by a high-pressure system,promoting westward fog expansion.Additionally,the backward trajectory analysis further indicated that the Foehn Clearance Effect of the Changbai Mountains extended its influence far beyond the immediate lee side,contributing to significant changes in atmospheric conditions such as reductions in relative humidity and increases in potential temperature.The dry,warm foehn contributed to a reduction in the liquid water content,ultimately leading to the weakening or even dissipation of the sea fog in the region close to the Changbai Mountains.This study emphasizes the crucial role of the Changbai Mountains’topography in the development and evolution of fog,providing valuable insights for forecasting fog in regions with complex terrain.展开更多
The impact of cross-sectional topographic variability on the kinetic properties of granular flows has been underexplored,which hinders the understanding of the kinematics of rock avalanches.In this study,the throat co...The impact of cross-sectional topographic variability on the kinetic properties of granular flows has been underexplored,which hinders the understanding of the kinematics of rock avalanches.In this study,the throat contraction index(T)is introduced to quantify variations in throat topography,and 96 numerical simulation experiments with varying T and slope angles(δ)are conducted.The findings indicate that granular flows experience transient obstructions when traversing throat topographies,primarily due to the periodic formation and breaking of the arch structure.Observations suggest that the acceleration of velocity in the tails of granular flows is restrained by the throat region,potentially altering the dynamics of related geohazards.In this study,the impact of throat topography is quantitatively assessed,demonstrating a reduction in peak flowrates of granular materials by 20%-80% and extending the flowduration up to six times.The present study proposes the throat-induced hazard index(Φ)to evaluate the influenceof throat topography on the risk of rockslides and avalanches characterized by granular flows,which may provide insights for the design of mitigation structures in topographic regions.展开更多
In the generation and propagation of nonlinear Rossby solitary waves within the atmosphere and ocean,topography occupies a pivotal role.This paper focuses on elucidating the impact of topography on such Rossby solitar...In the generation and propagation of nonlinear Rossby solitary waves within the atmosphere and ocean,topography occupies a pivotal role.This paper focuses on elucidating the impact of topography on such Rossby solitary waves.Utilizing the perturbation expansion method and spatialtemporal transformations,we derive the Korteweg–de Vries and modified Korteweg–de Vries equation(Gardner equation)governing the amplitude of nonlinear Rossby waves.A fundamental issue addressed herein is a Sturm–Liouville-type ordinary differential equation characterized by variable coefficients and fixed boundary conditions.To numerically solve the derived Korteweg–de Vries and modified Korteweg–de Vries equations,we employ a physical-informed neural network.Both qualitative and quantitative analyses are conducted to discuss the influences of topography andβeffects,respectively.展开更多
Corneal topography serves as an essential reference for diagnostic treatment in ophthalmology.Accurate corneal topography is crucial for clinical practice.In this study,the refractive power calculation was performed b...Corneal topography serves as an essential reference for diagnostic treatment in ophthalmology.Accurate corneal topography is crucial for clinical practice.In this study,the refractive power calculation was performed based on the initial corneal information collected using the Placido disc.A corneal point cloud model was established in polar coordinates,and an interpolation algorithm was proposed to fill missing points of the local bicubic B-spline by searching control points in the selfdefined interpolation matrix.The grid interpolation of the point cloud information and the smooth imaging of the final topographic map were achieved by Delaunay triangulation and Gaussian kernel function smoothing.Experiment results show that the proposed interpolation algorithm has higher accuracy than previous algorithms.The mean absolute error between the measured diopter of the original detection and the reconstructed is less than 0.300 D,indicating that this algorithm is feasible.展开更多
The textured roll and polished roll were applied instead of the ground roll in a 20-high mill to conduct two-pass rolling of 316L stainless steel strip with thickness of 0.027 mm.After the two-pass rolling with the te...The textured roll and polished roll were applied instead of the ground roll in a 20-high mill to conduct two-pass rolling of 316L stainless steel strip with thickness of 0.027 mm.After the two-pass rolling with the textured roll and polished roll(TPR),the surface roughness of the strip is dramatically reduced,and the surface topographical anisotropy index is diminished to 30.9%of the initial strip.Comparing with the strip rolled using the ground roll in both passes(GGR),the elongation of TPR rolled strip is obviously improved,and the mechanical property anisotropy is greatly weakened.The anisotropy index of tensile strength and elongation are 42.58%and 52.59%of that of GGR rolled strip,which is mainly attributed to the significant decrease of the texture intensity of the strip by TPR process.The results indicate that TPR process can obtain the stainless steel ultra-thin strip with smooth and uniform surface topography and good mechanical properties.展开更多
AIM:To investigate the impact of preoperative anterior corneal topographic parameters on the morphology of the postoperative effective optical zone(EOZ)in patients undergoing keratorefractive lenticule extraction(KLEx...AIM:To investigate the impact of preoperative anterior corneal topographic parameters on the morphology of the postoperative effective optical zone(EOZ)in patients undergoing keratorefractive lenticule extraction(KLEx)and wavefront-guided LASIK(WG-LASIK).METHODS:This retrospective study included 310 eyes from patients who underwent either KLEx(via small incision lenticule extraction,171 eyes)or WG-LASIK(139 eyes).Patients were stratified into subgroups based on the median values of spherical equivalent(SE)and anterior corneal topographic parameters.Postoperative EOZ parameters were measured 1mo after surgery and compared across subgroups.Correlation analysis and multivariable linear regression analysis were performed to explore the associations between preoperative anterior corneal topographic parameters and EOZ parameters.RESULTS:A total of 310 eyes were included(KLEx:171 eyes from 88 patients;WG-LASIK:139 eyes from 82 patients).The mean age was 30.65±5.67y in the KLEx cohort and 29.06±5.94y in the WG-LASIK cohort.In the KLEx cohort,SE,preoperative mean keratometry(Km),steep keratometry(K2),and anterior corneal astigmatism(K2-K1)were positively correlated with the postoperative optical zone reduction ratio(RR=EOZ/planned optical zone×100%;all P<0.01).Multivariable regression identified SE[β=0.027,95%confidence interval(CI):0.022-0.032,P<0.001],Km(β=0.009,95%CI:0.002-0.016,P=0.014),and anterior corneal astigmatism(β=0.031,95%CI:0.013-0.049,P<0.001)as significant predictors of RR(R²=0.456,P<0.001).In the WG-LASIK cohort,SE was positively correlated with RR(P<0.01);K2 and anterior corneal astigmatism were positively correlated with both RR(P<0.05)and EOZ eccentricity(P<0.01).Multivariable regression showed SE(β=0.015,95%CI:0.007-0.023,P<0.001)and anterior corneal astigmatism(β=0.029,95%CI:0.012-0.047,P=0.001)were significant predictors of RR(R²=0.121,P<0.001).CONCLUSION:Preoperative anterior corneal topographic parameters,particularly anterior corneal astigmatism,significantly affect postoperative EOZ morphology in both KLEx and WG-LASIK.Additionally,Km is a predictor of EOZ reduction specifically in KLEx.展开更多
BACKGROUND Despite growing evidence on endoscopic full thickness resection(EFTR),data on segment-specific outcomes in real-world patients remain limited.AIM To investigate segment-specific outcomes of EFTR using a ful...BACKGROUND Despite growing evidence on endoscopic full thickness resection(EFTR),data on segment-specific outcomes in real-world patients remain limited.AIM To investigate segment-specific outcomes of EFTR using a full-thickness resection device(FTRD)for neoplastic colorectal lesions.METHODS In this multicenter,retrospective study,EFTR was conducted in unselected realworld patients referred to participating German centers after colonoscopy confirmed EFTR eligibility.The primary outcome was histologically complete resection(R0)of the lesion,including segment-specific outcomes and adverse events(AE).Additional efficacy and safety parameters were investigated by colonic topography for up to 30 days.RESULTS The analysis included 102 patients(64 males,38 females)with a median age of 70 years.EFTR via FTRD was technically successful in all patients.The R0 rate was 81.4%,segment-specifically ranging from 85.0%(rectum),84.6%(descending colon),84.0%(ascending colon),83.3%(cecum),and 76.5%(sigmoid colon)to 73.3%(transverse colon).Examination time was longer in proximal parts compared to the rectosigmoid(non-significant).Overall,33 patients(32.4%)experienced AE,including only one major complication(0.98%;perforation of sigmoid colon).Abdominal postsurgical pain(18.6%),hematochezia(9.8%),and hemoglobin decline(7.8%)were the most frequent minor complications.Transverse colon lesions had the numerically highest rate of AE,with 8 of 15 patients(53.3%)affected.CONCLUSION EFTR is efficacious for neoplastic colorectal lesions,though R0 rates vary by location.This may impact patient education,selection of the operator,and consideration of laparoscopy surgery.展开更多
High-speed milling of titanium alloys is widely used in aviation and aerospace industries for its high efficiency and good quality.In order to optimize the machining parameters in high-speed milling TB6 titanium alloy...High-speed milling of titanium alloys is widely used in aviation and aerospace industries for its high efficiency and good quality.In order to optimize the machining parameters in high-speed milling TB6 titanium alloy,experiments of high-speed milling and fatigue were conducted to investigate the effect of parameters on 3D surface topography and fatigue life.Based on the fatigue fracture,the effect mechanism of surface topography on the fatigue crack initiation was proposed.The experiment results show that when the milling speed ranged from 100 m/min to 140 m/min,and the feed per tooth ranged from 0.02 mm/z to 0.06 mm/z,the obtained surface roughness were within the limit（0.8 μm）.Fatigue life decreased sharply with the increase of surface equivalent stress concentration factor.The average error of fatigue life between the established model and the experimental results was 6.25%.The fatigue cracks nucleated at the intersection edge of machined surface.展开更多
The forward modeling procedure used in this article is formulated with the volume integral equation based on the tensor Green＇s function. The electromagnetic components responses are first calculated in the frequency...The forward modeling procedure used in this article is formulated with the volume integral equation based on the tensor Green＇s function. The electromagnetic components responses are first calculated in the frequency domain and then transformed to the time domain by digital filtering. The valley and hill topography with a layered earth is stimulated by a horizontal electric dipole （HED） transmitter, which is common in field surveys, and the TEM responses are calculated at the transmitter and receivers. The topography effects on the long offset electromagnetic transient （LOTEM） responses are discussed in detail. The results show that both valley and hill topography has significant effect on the LOTEM measurement. If the HED is located in the bottom of a valley, the distortion of the observed anomalous field at distance is severe. A valley at the receiver locations show a strong effect but are localized in space and time. In general, hill-shaped topography shows smaller effects no matter where its located. When the topography is located between source and receivers, the influence is negligible. We conclude that the location of the source is much more important than the receivers and it is critical to put the transmitter in an open flat area in the field survey.展开更多
The protection and utilization of great historical sites mainly includes 4 modes,specifically,building the whole site into a park of historical relics;combining the site with the scenic area into a tourist site;buildi...The protection and utilization of great historical sites mainly includes 4 modes,specifically,building the whole site into a park of historical relics;combining the site with the scenic area into a tourist site;building the site into a forest park;combining site protection with development of modern agriculture so as to build an agricultural park of historical and cultural relics.In this study,it was emphasized that landscape design of such parks should first be based on the protection of historical relics.Among all constructed parks of historical relics in China,Relics of Sweet Spring Palace,Tomb of the Military Marquis Zhuge Liang and Mausoleum of the Yellow Emperor were taken as examples to demonstrate how large-scale topographical elements form the spatial pattern of garden landscapes;Ruins of the Old Summer Palace and the Park of Qujiang Pool Relics were taken to show how moderate-scale topographical elements form the spatial division of garden landscapes;by giving examples of micro-relief slope utilization,micro-relief stone and water layout,utilization of original reliefs and micro-relief functions,this study illustrated how such micro-scale topographical elements form landscape nodes in gardens,and specifically introduced functions of micro-relief,such as dividing and controlling spaces,creating aesthetic value,improving micro-climate and so on.Moreover,cases of terrain utilization and creation in classical western gardens were given,and masterworks of some modern western garden designers were borrowed and analyzed to find valuable concepts for designing parks of historical relics in China.展开更多
We studied finite-element-method-based two-dimensional frequency-domain acoustic FWI under rugged topography conditions. The exponential attenuation boundary condition suitable for rugged topography is proposed to sol...We studied finite-element-method-based two-dimensional frequency-domain acoustic FWI under rugged topography conditions. The exponential attenuation boundary condition suitable for rugged topography is proposed to solve the cutoff botmdary problem as well as to consider the requirement of using the same subdivision grid in joint multifrequency inversion. The proposed method introduces the attenuation factor, and by adjusting it, acoustic waves are sufficiently attenuated in the attenuation layer to minimize the cutoff boundary effect. Based on the law of exponential attenuation, expressions for computing the attenuation factor and the thickness of attenuation layers are derived for different frequencies. In multifrequency-domain FWI, the conjugate gradient method is used to solve equations in the Gauss-Newton algorithm and thus minimize the computation cost in calculating the Hessian matrix. In addition, the effect of initial model selection and frequency combination on FWI is analyzed. Examples using numerical simulations and FWI calculations are used to verify the efficiency of the proposed method.展开更多
As fundamental parameters of the Antarctic Ice Sheet,ice thickness and subglacial topography are critical factors for studying the basal conditions and mass balance in Antarctica.During CHINARE 24（the 24 th Chinese N...As fundamental parameters of the Antarctic Ice Sheet,ice thickness and subglacial topography are critical factors for studying the basal conditions and mass balance in Antarctica.During CHINARE 24（the 24 th Chinese National Antarctic Research Expedition,2007/08）,the research team used a deep ice-penetrating radar system to measure the ice thickness and subglacial topography of the ＂Chinese Wall＂ around Kunlun Station,East Antarctica.Preliminary results show that the ice thickness varies mostly from 1600 m to 2800 m along the ＂Chinese Wall＂,with the thickest ice being 3444 m,and the thinnest ice 1255 m.The average bedrock elevation is 1722 m,while the minimum is just 604 m.Compared with the northern side of the ice divide,the ice thickness is a little greater and the subglacial topography lower on the southern side,which is also characterized by four deep valleys.We found no basal freeze-on ice in the Gamburtsev Subglacial Mountains area,subglacial lakes,or water bodies along the ＂Chinese Wall＂.Ice thickness and subglacial topography data extracted from the Bedmap 2 database along the ＂Chinese Wall＂ are consistent with our results,but their resolution and accuracy are very limited in areas where the bedrock fluctuates intensely.The distribution of ice thickness and subglacial topography detected by ice-penetrating radar clarifies the features of the ice sheet in this ＂inaccessible＂ region.These results will help to advance the study of ice sheet dynamics and the determination of future locations of the GSM＇s geological and deep ice core drilling sites in the Dome A region.展开更多
In order to eliminate the effect of ocean bottom topography on seismic wave field,we transformed curved（x,z）coordinate system grids into rectangular（ξ,η）coordinate system grids and derived a 2-D scalar acoustic ...In order to eliminate the effect of ocean bottom topography on seismic wave field,we transformed curved（x,z）coordinate system grids into rectangular（ξ,η）coordinate system grids and derived a 2-D scalar acoustic wave equation in theξ,ηdomain.The seismic wave field collected at the sea surface was downward continued to the ocean bottom by the inverse finite difference method with the water velocity and then was reversely continued to the ocean surface by the finite difference method using the layer velocity from just below the ocean bottom in the（ξ,η）domain.Simulation calculations and practical application show that this method can not only remove the reflection travel time distortion but also correct the dynamic parameter changes caused by the ocean bottom topography.The inverted velocity after wave field continuation is much more accurate than before continuation and the image section was greatly improved compared to the original wave field.展开更多
文摘New information and communication technologies have led to the emergence of new techniques in our daily lives. Indeed, in topography, a lightning development of new techniques and new devices has been noticed. This development has given rise to a multitude of choices of devices and various classes of precision. This implies that the decision-makers have to study the adequate equipment and the appropriate technique according to the topographic task to be realized. The objective is not to compare GNSS and topographic techniques, but to point out the contribution of the Global Navigation Satelite System (GNSS) techniques of topographic work. Thus, a theoretical study with a critical eye on the scientific principle of calculating the third topographic dimension followed by a leveling campaign, Real Time Kinematic (RTK) surveys will be used in order to be able to compare and interpret the result from these campaigns. The study of the difference resulting from the practical campaigns will allow us to identify the contribution of GNSS technology.
基金supported by the Guangdong Province Introduced Innovative R&D Team of Big Data-Mathematical Earth Sciences and Extreme Geological Events Team(grant number 2021ZT09H399)the National Natural Science Foundation of China(grant number 42430111,42050103).
文摘The investigations of physical attributes of oceans,including parameters such as heat flow and bathymetry,have garnered substantial attention and are particularly valuable for examining Earth’s thermal structures and dynamic processes.Nevertheless,classical plate cooling models exhibit disparities when predicting observed heat flow and seafloor depth for extremely young and old lithospheres.Furthermore,a comprehensive analysis of global heat flow predictions and regional ocean heat flow or bathymetry data with physical models has been lacking.In this study,we employed power-law models derived from the singularity theory of fractal density to meticulously fit the latest ocean heat flow and bathymetry.Notably,power-law models offer distinct advantages over traditional plate cooling models,showcasing robust self-similarity,scale invariance,or scaling properties,and providing a better fit to observed data.The outcomes of our singularity analysis concerning heat flow and bathymetry across diverse oceanic regions exhibit a degree of consistency with the global ocean spreading rate model.In addition,we applied the similarity method to predict a higher resolution(0.1°×0.1°)global heat flow map based on the most recent heat flow data and geological/geophysical observables refined through linear correlation analysis.Regions displaying significant disparities between predicted and observed heat flow are closely linked to hydrothermal vent fields and active structures.Finally,combining the actual bathymetry and predicted heat flow with the power-law models allows for the quantitative and comprehensive detection of anomalous regions of ocean subsidence and heat flow,which deviate from traditional plate cooling models.The anomalous regions of subsidence and heat flow show different degrees of anisotropy,providing new ideas and clues for further analysis of ocean topography or hydrothermal circulation of mid-ocean ridges.
文摘Traumatic injuries to the central nervous system(CNS) result in disruption of the intricate network of axons which connect functionally related neurons that are widely distributed throughout the brain and spinal cord.Under normal conditions,maintenance of this complex system is structurally and functionally supported by astrocytes (ACs)and other glial cells,the processes of which form a framework surrounding neuronal cell bodies,dendrites,axons,and synapses.
基金funded by the Yunnan Provincial Basic Research Joint Special Fund Project(2019FH001(-052))Cangshan Mountain Synthetic Scientific Expeditions Fund.
文摘The Hengduan Mountains,situated on the southeastern edge of the Qinghai-Tibet Plateau,are the longest and widest north-south-oriented mountain range in China,exerting a significant influence on the ecological and geographical pattern.Understanding the topographic and geomorphological characteristics of the Hengduan Mountains is fundamental and crucial for research in related fields such as ecology,geography,and sustainability.In this study,Digital Elevation Model(DEM)data were utilized to extract and analyze the topography and geomorphology(TG)pattern.TG maps have been developed to quantitatively classify the TG types in the Hengduan Mountains by combining the five factors of elevation,slope,aspect,relief and landform.The spatial distribution and quantitative characteristics of these factors were mapped and investigated using geographic information systems.The results revealed that:(1)The Hengduan Mountains exhibit an elongated north-south distribution,with an average elevation of approximately 3746 m,an average slope of around 25°,and an average relief of about 266 m.(2)The Hengduan Mountains display significant elevation differences,with an overall high elevation,characterized by a trend of lower elevation in the east and higher elevation in the west,as well as irregular orientations of various aspects.(3)The 19 landform types were identified,the landform types of the Hengduan Mountains are primarily composed of low-relief high-mountains(42.0618%),low-relief mid-mountains(22.4624%),and high-elevation hills(20.5839%).The results of the study can provide data and information support for the ecology,environmental protection and sustainable development of the Hengduan Mountains.
基金supported by the National Natural Sci-ence Foundation of China(No.U2106204)the Shanxi Water Conservancy Science and Technology Re-search and Extension Project(No.2023ZF19).
文摘Progressive modifications in submarine topography and shorelines drastically affect tidal dynamics in bays.This study examines the influence of topographic slope,bay length,and driving forces on tidal currents following land reclamation.Tidal equa-tions are analytically solved using infinite series,deriving expressions for tidal levels and currents in narrow bays with varying topog-raphy.Tidal levels,influenced by topographic variations,are characterized by amplitude and phase lag of their complex amplitude.These levels demonstrate high sensitivity to longitudinal slope variations but remain relatively stable under lateral slope changes.Un-der constant topographic slopes,even minor changes in bay length can drastically modify amplitude and phase lag,highlighting the sensitivity of tidal dynamics to geometric alterations.Tidal velocity notably increases with steeper longitudinal slopes and modestly rises with elevated lateral slopes.However,changes in longitudinal and lateral slopes do not considerably alter flow patterns.While external forces predominantly regulate tidal velocity with negligible effects on flow patterns,endogenous resistance influences veloci-ty but minimally impacts flow structure.These findings enhance the understanding of tidal responses to geometric and topographic changes,providing valuable guidance for land reclamation projects and coastal management strategies.
基金Supported by the National Natural Science Foundation of China(No.82201195).
文摘AIM:To evaluate the potential of artificial intelligence(AI)for automating corneal topography interpretation in orthokeratology patients,aiming to enhance diagnostic precision,efficiency,and clinical decision-making in myopia management.METHODS:The 1469 corneal topography images from 582 eyes of 326 myopic children treated with orthokeratology lenses over 47mo were collected.Each sample was categorized by decentration,treatment zone size,shape variation,and eye laterality.A multi-task AI model was developed to predict these parameters,with performance measured using area under curve(AUC),accuracy,and F1 scores.We compared AI-only,humanonly,and combined Human+AI approaches on a subset of 100 images.External validation with images from additional hospitals tested model generalizability.RESULTS:The model achieved high accuracy in eyeside prediction(AUC 0.95)and AUC values of 0.52-0.74 for decentration,treatment zone,and shape variation tasks.The combined Human+AI method outperformed AI-only and human-only approaches,achieving the highest accuracy(up to 87%)and fastest processing time(80ms).External validation confirmed robust performance in simple tasks,though accuracy was lower for complex classifications due to imaging variations.CONCLUSION:AI provides efficient routine corneal topography assessments,while complex cases benefit most from a Human+AI approach,particularly in scenarios requiring nuanced clinical interpretation.The model currently functions as an assistive tool.
基金jointly supported by the National Natural Science Foundation of China[grant number 42205009]the Open Grants of the State Key Laboratory of Severe Weather[grant number 2024LASWB23]+1 种基金the Collaborative Innovation Project for Marine Meteorological Science and Technology in the Bohai Rim Region[grant number QYXM202315]the Research and Development Project of Hebei Provincial Meteorological Bureau[grant number 22ky26]。
文摘Fog is a highly complex weather phenomenon influenced by numerous factors.This study investigated the impact of the Changbai Mountains’topography on the formation and development of spring fog in the Bohai Sea.From 12 to 14 May 2021,the Bohai region experienced a sea fog event.Utilizing Himawari-8 satellite data,ERA5 reanalysis dataset,land and sea station observations,the WRF model,a topography sensitivity experiment,and backward trajectory tracking,the influence of the Changbai Mountains’topography on the evolution of this sea fog event was assessed.Results indicated that the Changbai Mountains’topography significantly impacted the propagation and concentration of the sea fog through dual effects—namely,the Venturi Effect and Foehn Clearance Effect.Comparative simulations incorporating and excluding the Changbai Mountains revealed that its topography favored weak convergence(Venturi Effect)of low-level airflow over the Bohai Sea induced by a high-pressure system,promoting westward fog expansion.Additionally,the backward trajectory analysis further indicated that the Foehn Clearance Effect of the Changbai Mountains extended its influence far beyond the immediate lee side,contributing to significant changes in atmospheric conditions such as reductions in relative humidity and increases in potential temperature.The dry,warm foehn contributed to a reduction in the liquid water content,ultimately leading to the weakening or even dissipation of the sea fog in the region close to the Changbai Mountains.This study emphasizes the crucial role of the Changbai Mountains’topography in the development and evolution of fog,providing valuable insights for forecasting fog in regions with complex terrain.
基金supported by the National Natural Science Foundation of China(Grant Nos.42307194 and 42120104002)the Young Elite Scientists Sponsorship Program by CAST(Grant No.2024QNRC001).
文摘The impact of cross-sectional topographic variability on the kinetic properties of granular flows has been underexplored,which hinders the understanding of the kinematics of rock avalanches.In this study,the throat contraction index(T)is introduced to quantify variations in throat topography,and 96 numerical simulation experiments with varying T and slope angles(δ)are conducted.The findings indicate that granular flows experience transient obstructions when traversing throat topographies,primarily due to the periodic formation and breaking of the arch structure.Observations suggest that the acceleration of velocity in the tails of granular flows is restrained by the throat region,potentially altering the dynamics of related geohazards.In this study,the impact of throat topography is quantitatively assessed,demonstrating a reduction in peak flowrates of granular materials by 20%-80% and extending the flowduration up to six times.The present study proposes the throat-induced hazard index(Φ)to evaluate the influenceof throat topography on the risk of rockslides and avalanches characterized by granular flows,which may provide insights for the design of mitigation structures in topographic regions.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12462021,12102205,12262025)the Central Guidance for Local Scientific and Technological Development Funding Projects(Grant No.2024ZY0117)+2 种基金the Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(Grant No.NJYT23098)the Scientific Starting and the Innovative Research Team in the Universities of Inner Mongolia Autonomous Region of China(Grant No.NMGIRT2208)the National College Students Innovation and Entrepreneurship Training Program(Grant No.202410126024)。
文摘In the generation and propagation of nonlinear Rossby solitary waves within the atmosphere and ocean,topography occupies a pivotal role.This paper focuses on elucidating the impact of topography on such Rossby solitary waves.Utilizing the perturbation expansion method and spatialtemporal transformations,we derive the Korteweg–de Vries and modified Korteweg–de Vries equation(Gardner equation)governing the amplitude of nonlinear Rossby waves.A fundamental issue addressed herein is a Sturm–Liouville-type ordinary differential equation characterized by variable coefficients and fixed boundary conditions.To numerically solve the derived Korteweg–de Vries and modified Korteweg–de Vries equations,we employ a physical-informed neural network.Both qualitative and quantitative analyses are conducted to discuss the influences of topography andβeffects,respectively.
基金Shanghai Science and Technology Program,China (No.20DZ2251400)。
文摘Corneal topography serves as an essential reference for diagnostic treatment in ophthalmology.Accurate corneal topography is crucial for clinical practice.In this study,the refractive power calculation was performed based on the initial corneal information collected using the Placido disc.A corneal point cloud model was established in polar coordinates,and an interpolation algorithm was proposed to fill missing points of the local bicubic B-spline by searching control points in the selfdefined interpolation matrix.The grid interpolation of the point cloud information and the smooth imaging of the final topographic map were achieved by Delaunay triangulation and Gaussian kernel function smoothing.Experiment results show that the proposed interpolation algorithm has higher accuracy than previous algorithms.The mean absolute error between the measured diopter of the original detection and the reconstructed is less than 0.300 D,indicating that this algorithm is feasible.
基金supported by the National Natural Science Foundation of China(Nos.51974196,52275361,and 52305406)the Key Projects of the National Natural Science Foundation of China(No.U22A20188)the Special Projects of the Central Government in Guidance of Local Science and Technology Development(YDZX20191400002149).
文摘The textured roll and polished roll were applied instead of the ground roll in a 20-high mill to conduct two-pass rolling of 316L stainless steel strip with thickness of 0.027 mm.After the two-pass rolling with the textured roll and polished roll(TPR),the surface roughness of the strip is dramatically reduced,and the surface topographical anisotropy index is diminished to 30.9%of the initial strip.Comparing with the strip rolled using the ground roll in both passes(GGR),the elongation of TPR rolled strip is obviously improved,and the mechanical property anisotropy is greatly weakened.The anisotropy index of tensile strength and elongation are 42.58%and 52.59%of that of GGR rolled strip,which is mainly attributed to the significant decrease of the texture intensity of the strip by TPR process.The results indicate that TPR process can obtain the stainless steel ultra-thin strip with smooth and uniform surface topography and good mechanical properties.
文摘AIM:To investigate the impact of preoperative anterior corneal topographic parameters on the morphology of the postoperative effective optical zone(EOZ)in patients undergoing keratorefractive lenticule extraction(KLEx)and wavefront-guided LASIK(WG-LASIK).METHODS:This retrospective study included 310 eyes from patients who underwent either KLEx(via small incision lenticule extraction,171 eyes)or WG-LASIK(139 eyes).Patients were stratified into subgroups based on the median values of spherical equivalent(SE)and anterior corneal topographic parameters.Postoperative EOZ parameters were measured 1mo after surgery and compared across subgroups.Correlation analysis and multivariable linear regression analysis were performed to explore the associations between preoperative anterior corneal topographic parameters and EOZ parameters.RESULTS:A total of 310 eyes were included(KLEx:171 eyes from 88 patients;WG-LASIK:139 eyes from 82 patients).The mean age was 30.65±5.67y in the KLEx cohort and 29.06±5.94y in the WG-LASIK cohort.In the KLEx cohort,SE,preoperative mean keratometry(Km),steep keratometry(K2),and anterior corneal astigmatism(K2-K1)were positively correlated with the postoperative optical zone reduction ratio(RR=EOZ/planned optical zone×100%;all P<0.01).Multivariable regression identified SE[β=0.027,95%confidence interval(CI):0.022-0.032,P<0.001],Km(β=0.009,95%CI:0.002-0.016,P=0.014),and anterior corneal astigmatism(β=0.031,95%CI:0.013-0.049,P<0.001)as significant predictors of RR(R²=0.456,P<0.001).In the WG-LASIK cohort,SE was positively correlated with RR(P<0.01);K2 and anterior corneal astigmatism were positively correlated with both RR(P<0.05)and EOZ eccentricity(P<0.01).Multivariable regression showed SE(β=0.015,95%CI:0.007-0.023,P<0.001)and anterior corneal astigmatism(β=0.029,95%CI:0.012-0.047,P=0.001)were significant predictors of RR(R²=0.121,P<0.001).CONCLUSION:Preoperative anterior corneal topographic parameters,particularly anterior corneal astigmatism,significantly affect postoperative EOZ morphology in both KLEx and WG-LASIK.Additionally,Km is a predictor of EOZ reduction specifically in KLEx.
文摘BACKGROUND Despite growing evidence on endoscopic full thickness resection(EFTR),data on segment-specific outcomes in real-world patients remain limited.AIM To investigate segment-specific outcomes of EFTR using a full-thickness resection device(FTRD)for neoplastic colorectal lesions.METHODS In this multicenter,retrospective study,EFTR was conducted in unselected realworld patients referred to participating German centers after colonoscopy confirmed EFTR eligibility.The primary outcome was histologically complete resection(R0)of the lesion,including segment-specific outcomes and adverse events(AE).Additional efficacy and safety parameters were investigated by colonic topography for up to 30 days.RESULTS The analysis included 102 patients(64 males,38 females)with a median age of 70 years.EFTR via FTRD was technically successful in all patients.The R0 rate was 81.4%,segment-specifically ranging from 85.0%(rectum),84.6%(descending colon),84.0%(ascending colon),83.3%(cecum),and 76.5%(sigmoid colon)to 73.3%(transverse colon).Examination time was longer in proximal parts compared to the rectosigmoid(non-significant).Overall,33 patients(32.4%)experienced AE,including only one major complication(0.98%;perforation of sigmoid colon).Abdominal postsurgical pain(18.6%),hematochezia(9.8%),and hemoglobin decline(7.8%)were the most frequent minor complications.Transverse colon lesions had the numerically highest rate of AE,with 8 of 15 patients(53.3%)affected.CONCLUSION EFTR is efficacious for neoplastic colorectal lesions,though R0 rates vary by location.This may impact patient education,selection of the operator,and consideration of laparoscopy surgery.
基金Projects(50975237,51005184) supported by the National Natural Science Foundation of China
文摘High-speed milling of titanium alloys is widely used in aviation and aerospace industries for its high efficiency and good quality.In order to optimize the machining parameters in high-speed milling TB6 titanium alloy,experiments of high-speed milling and fatigue were conducted to investigate the effect of parameters on 3D surface topography and fatigue life.Based on the fatigue fracture,the effect mechanism of surface topography on the fatigue crack initiation was proposed.The experiment results show that when the milling speed ranged from 100 m/min to 140 m/min,and the feed per tooth ranged from 0.02 mm/z to 0.06 mm/z,the obtained surface roughness were within the limit（0.8 μm）.Fatigue life decreased sharply with the increase of surface equivalent stress concentration factor.The average error of fatigue life between the established model and the experimental results was 6.25%.The fatigue cracks nucleated at the intersection edge of machined surface.
基金supported by National Natural Science Foundation of China (Nos. 40727001, 40774073, and 40774074)the National Basic Research Programs of China (973 Program) (No. 2007CB209607)the Doctoral Program of Higher Research and Special funds (No. 20070489001)
文摘The forward modeling procedure used in this article is formulated with the volume integral equation based on the tensor Green＇s function. The electromagnetic components responses are first calculated in the frequency domain and then transformed to the time domain by digital filtering. The valley and hill topography with a layered earth is stimulated by a horizontal electric dipole （HED） transmitter, which is common in field surveys, and the TEM responses are calculated at the transmitter and receivers. The topography effects on the long offset electromagnetic transient （LOTEM） responses are discussed in detail. The results show that both valley and hill topography has significant effect on the LOTEM measurement. If the HED is located in the bottom of a valley, the distortion of the observed anomalous field at distance is severe. A valley at the receiver locations show a strong effect but are localized in space and time. In general, hill-shaped topography shows smaller effects no matter where its located. When the topography is located between source and receivers, the influence is negligible. We conclude that the location of the source is much more important than the receivers and it is critical to put the transmitter in an open flat area in the field survey.
文摘The protection and utilization of great historical sites mainly includes 4 modes,specifically,building the whole site into a park of historical relics;combining the site with the scenic area into a tourist site;building the site into a forest park;combining site protection with development of modern agriculture so as to build an agricultural park of historical and cultural relics.In this study,it was emphasized that landscape design of such parks should first be based on the protection of historical relics.Among all constructed parks of historical relics in China,Relics of Sweet Spring Palace,Tomb of the Military Marquis Zhuge Liang and Mausoleum of the Yellow Emperor were taken as examples to demonstrate how large-scale topographical elements form the spatial pattern of garden landscapes;Ruins of the Old Summer Palace and the Park of Qujiang Pool Relics were taken to show how moderate-scale topographical elements form the spatial division of garden landscapes;by giving examples of micro-relief slope utilization,micro-relief stone and water layout,utilization of original reliefs and micro-relief functions,this study illustrated how such micro-scale topographical elements form landscape nodes in gardens,and specifically introduced functions of micro-relief,such as dividing and controlling spaces,creating aesthetic value,improving micro-climate and so on.Moreover,cases of terrain utilization and creation in classical western gardens were given,and masterworks of some modern western garden designers were borrowed and analyzed to find valuable concepts for designing parks of historical relics in China.
基金financially supported by the National High Technology Research and Development Program of China(No.2012AA09A20105)the National Science Foundation Network(No.41574127)
文摘We studied finite-element-method-based two-dimensional frequency-domain acoustic FWI under rugged topography conditions. The exponential attenuation boundary condition suitable for rugged topography is proposed to solve the cutoff botmdary problem as well as to consider the requirement of using the same subdivision grid in joint multifrequency inversion. The proposed method introduces the attenuation factor, and by adjusting it, acoustic waves are sufficiently attenuated in the attenuation layer to minimize the cutoff boundary effect. Based on the law of exponential attenuation, expressions for computing the attenuation factor and the thickness of attenuation layers are derived for different frequencies. In multifrequency-domain FWI, the conjugate gradient method is used to solve equations in the Gauss-Newton algorithm and thus minimize the computation cost in calculating the Hessian matrix. In addition, the effect of initial model selection and frequency combination on FWI is analyzed. Examples using numerical simulations and FWI calculations are used to verify the efficiency of the proposed method.
基金supported by National Basic Research Program of China(Grant Nos.2013CBA01804 and 2012CB957702)the Chinese Polar Environmental Comprehensive Investigation and Assessment Programs(Grant No.CHINARE-02-02)the National Science Foundation of China(Grant No.41101071)
文摘As fundamental parameters of the Antarctic Ice Sheet,ice thickness and subglacial topography are critical factors for studying the basal conditions and mass balance in Antarctica.During CHINARE 24（the 24 th Chinese National Antarctic Research Expedition,2007/08）,the research team used a deep ice-penetrating radar system to measure the ice thickness and subglacial topography of the ＂Chinese Wall＂ around Kunlun Station,East Antarctica.Preliminary results show that the ice thickness varies mostly from 1600 m to 2800 m along the ＂Chinese Wall＂,with the thickest ice being 3444 m,and the thinnest ice 1255 m.The average bedrock elevation is 1722 m,while the minimum is just 604 m.Compared with the northern side of the ice divide,the ice thickness is a little greater and the subglacial topography lower on the southern side,which is also characterized by four deep valleys.We found no basal freeze-on ice in the Gamburtsev Subglacial Mountains area,subglacial lakes,or water bodies along the ＂Chinese Wall＂.Ice thickness and subglacial topography data extracted from the Bedmap 2 database along the ＂Chinese Wall＂ are consistent with our results,but their resolution and accuracy are very limited in areas where the bedrock fluctuates intensely.The distribution of ice thickness and subglacial topography detected by ice-penetrating radar clarifies the features of the ice sheet in this ＂inaccessible＂ region.These results will help to advance the study of ice sheet dynamics and the determination of future locations of the GSM＇s geological and deep ice core drilling sites in the Dome A region.
基金sponsored by the National 973 Program of China(Grant No.2009CB219505)International Science&Technology Cooperation Program of China(Grant No.2010DFA21630)
文摘In order to eliminate the effect of ocean bottom topography on seismic wave field,we transformed curved（x,z）coordinate system grids into rectangular（ξ,η）coordinate system grids and derived a 2-D scalar acoustic wave equation in theξ,ηdomain.The seismic wave field collected at the sea surface was downward continued to the ocean bottom by the inverse finite difference method with the water velocity and then was reversely continued to the ocean surface by the finite difference method using the layer velocity from just below the ocean bottom in the（ξ,η）domain.Simulation calculations and practical application show that this method can not only remove the reflection travel time distortion but also correct the dynamic parameter changes caused by the ocean bottom topography.The inverted velocity after wave field continuation is much more accurate than before continuation and the image section was greatly improved compared to the original wave field.
