To study the rock deformation with three- dimensional model under rolling forces of disc cutter, by car- rying out the circular-grooving test with disc cutter rolling around on the rock, the rock mechanical behavior u...To study the rock deformation with three- dimensional model under rolling forces of disc cutter, by car- rying out the circular-grooving test with disc cutter rolling around on the rock, the rock mechanical behavior under rolling disc cutter is studied, the mechanical model of disc cutter rolling around the groove is established, and the the- ory of single-point and double-angle variables is proposed. Based on this theory, the physics equations and geometric equations of rock mechanical behavior under disc cutters of tunnel boring machine （TBM） are studied, and then the bal- ance equations of interactive forces between disc cutter and rock are established. Accordingly, formulas about normal force, rolling force and side force of a disc cutter are de- rived, and their validity is studied by tests. Therefore, a new method and theory is proposed to study rock- breaking mech- anism of disc cutters.展开更多
A hybrid model combining Fully Non-Linear Potential Flow Theory(FNPT)based on the Finite Element Method(FEM)and the Unified Navier-Stokes equation,using the 3D Improved Meshless Local Petrov Galerkin method with Ranki...A hybrid model combining Fully Non-Linear Potential Flow Theory(FNPT)based on the Finite Element Method(FEM)and the Unified Navier-Stokes equation,using the 3D Improved Meshless Local Petrov Galerkin method with Rankine Source(IMLPG_R),is developed to study wave interactions with a porous layer.In previous studies,the above formulations are applied to wave interaction with fixed cylindrical structures.The present study extends this framework by integrating a unified governing equation within the hybrid modeling approach to capture the dynamics of wave interaction with porous media.The porous layers are employed to replicate the wave-dissipating behavior of the structure.A weak coupling strategy is implemented within a designated buffer zone,wherein field variables from the 2D Fully Nonlinear Potential Theory(FNPT)simulations are transferred to the 3D Improved Moving Least Squares-based Petrov-Galerkin(IMLPG_R)model at each time step.This domain decomposition significantly reduces computational cost compared to a full 3D simulation by partitioning the domain into two subregions:the FNPT domain representing the far-field without structures,and the IMLPG_R domain encompassing the porous region.The Unified Navier-Stokes formulation is extended by incorporating additional drag forces governed by Darcy’s law to model the resistance introduced by the porous medium.A stationary background node framework is utilized for interpolation by fluid particles at each time step to accommodate the porous representation.To enhance numerical stability and accuracy,particularly in the presence of sloping boundaries,the Particle Shifting Technique(PST)is integrated into the IMLPG_R model.This implementation involves a modified version of the PST algorithm,where key parameters such as the weight function,velocity ratio,and radius of influence are optimized for IMLPG_R.This is the first time the application of 3D IMLPG_R for porous structure has been reported.Further,the model is subsequently validated against experimental data.展开更多
Neurodegenerative disorders represent an increasingly pertinent public health crisis.As a greater proportion of the population ages,neurodegenerative disorders and other diseases of aging place undue burdens on patien...Neurodegenerative disorders represent an increasingly pertinent public health crisis.As a greater proportion of the population ages,neurodegenerative disorders and other diseases of aging place undue burdens on patients,caregivers,and healthcare workers.Alzheimer’s disease(AD)and Parkinson’s disease represent the two most common neurodegenerative disorders in the population,affecting over 65 million people,worldwide.展开更多
To comprehensively utilize the valuable geological map,exploration profile,borehole,and geochemical logging data and the knowledge on the formation of the Jinshan Ag-Au deposit for forecasting the exploration targets ...To comprehensively utilize the valuable geological map,exploration profile,borehole,and geochemical logging data and the knowledge on the formation of the Jinshan Ag-Au deposit for forecasting the exploration targets of concealed ore bodies,three-dimensional Mineral Prospectivity Modeling(MPM)of the deposit has been conducted using the weights-of-evidence(WofE)method.Conditional independence between evidence layers was tested,and the outline results using the prediction-volume(P-V)and Student's t-statistic methods for delineating favorable mineralization areas from continuous posterior probability map were critically compared.Four exploration targets delineated ultimately by the Student's t-statistic method for the discovery of minable ore bodies in each of the target areas were discussed in detail.The main conclusions include:(1)three-dimensional modeling of a deposit using multi-source reconnaissance data is useful for MPM in interpreting their relationships with known ore bodies;(2)WofE modeling can be used as a straightforward tool for integrating deposit model and reconnaissance data in MPM;(3)the Student's t-statistic method is more applicable in binarizing the continuous prospectivity map for exploration targeting than the PV approach;and(4)two target areas within high potential to find undiscovered ore bodies were diagnosed to guide future near-mine exploration activities of the Jinshan deposit.展开更多
Background:Traditional imaging approaches to keratoconus(KCN)have thus far failed to produce a standardized approach for diagnosis.While many diagnostic modalities and metrics exist,none have proven robust enough to b...Background:Traditional imaging approaches to keratoconus(KCN)have thus far failed to produce a standardized approach for diagnosis.While many diagnostic modalities and metrics exist,none have proven robust enough to be considered a gold standard.This study aims to introduce novel metrics to differentiate between KCN and healthy corneas using three-dimensional(3D)measurements of surface area and volume.Methods:This retrospective observational study examined KCN patients along with healthy control patients between the ages of 20 and 79 years old at the University of Maryland,Baltimore.The selected patients underwent a nine-line raster scan anterior segment optical coherence tomography(AS-OCT).ImageJ was used to determine the central 6 mm of each image and each corneal image was then divided into six 1 mm segments.Free-D software was then used to render the nine different images into a 3D model to calculate corneal surface area and volume.A two-tailed Mann-Whitney test was used to assess statistical significance when comparing these subsets.Results:Thirty-three eyes with KCN,along with 33 healthy control,were enrolled.There were statistically significant differences between the healthy and KCN groups in the metric of anterior corneal surface area(13.927 vs.13.991 mm^(2),P=0.046),posterior corneal surface area(14.045 vs.14.173 mm^(2),P<0.001),and volume(8.430 vs.7.773 mm3,P<0.001)within the central 6 mm.Conclusions:3D corneal models derived from AS-OCT can be used to measure anterior corneal surface area,posterior corneal surface area,and corneal volume.All three parameters are statistically different between corneas with KCN and healthy corneas.Further study and application of these parameters may yield new methodologies for the detection of KCN.展开更多
Background:Successful liver resection in oncologic surgery depends on safety,precision,and efficacy,all of which require a thorough understanding of liver anatomy.Contrast-enhanced computed tomography(CT)-generated th...Background:Successful liver resection in oncologic surgery depends on safety,precision,and efficacy,all of which require a thorough understanding of liver anatomy.Contrast-enhanced computed tomography(CT)-generated three-dimensional(3D)models have been proposed as a valuable tool to enhance this understanding.However,a systematic comparison of different display modalities across professional groups has not yet been performed.Methods:In this prospective,monocentric randomized trial,we compared high-resolution twodimensional(2D)CT images of liver malignancies with their corresponding standardized,non-colored 3D virtual and printed models in facilitating anatomical and spatial understanding as well as surgical decision-making.A total of 91 participants,including 40 surgeons,10 radiologists,and 41 students,evaluated six clinical cases(three centrally and three peripherally located liver malignancies).Each participant assessed one central and one peripheral case per display modality,presented in a random order.Results:Compared to 2D CT images,both 3D virtual and printed models significantly improved the identification of tumor location(P<0.001),enhanced the comprehension of spatial relationships with adjacent liver and portal veins(P<0.001 and P=0.019,respectively),and facilitated clinical decisionmaking(P<0.001).No significant difference was observed between virtual and printed models in terms of effectiveness.Within the different groups,surgeons and students,but not radiologists,more accurately identified tumor location and spatial relationships with adjacent liver and portal veins using 3D models.Subjectively,most surgeons and students preferred 3D printed models over virtual models and 2D CT images.Conclusions:This study demonstrated that standardized,non-colored 3D virtual and printed models equally help preoperative anatomical understanding and decision-making,particularly for surgeons and students.By isolating the influence of display modality,our findings clarify prior inconsistent results and support the integration of cost-effective 3D visualization by applying virtual models into surgical planning and education.Preference for printed models despite comparable efficacy highlights the importance of user-centered implementation strategies.展开更多
Climate warming is significantly altering the distribution of tree species,which holds crucial implications for China’s Larix species as they are important afforestation efforts.Understanding their optimal habitats a...Climate warming is significantly altering the distribution of tree species,which holds crucial implications for China’s Larix species as they are important afforestation efforts.Understanding their optimal habitats and environmental constraints is vital for predicting range shifts and guiding adaptive forest management.Previous studies prioritized changing climate impacts on horizontal range shifts of Larix,neglecting the influence of soil factors and range shift along altitudinal gradients.To address this,we applied an optimized MaxEnt model to assess current and future SSP126/SSP585 scenarios,three-dimensional habitat suitability(latitude,longitude,altitude)for four major Larix species(L.principis-rupprechtii,L.gmelinii,L.kaempferi,L.olgensis),while identifying key environmental drivers.Our results indicate that elevation and extreme moisture conditions universally constrain their distribution.Soil chemistry properties exhibited species-specific influences:cation exchange capacity critically shaped L.principis-rupprechtii and L.gmelinii ranges,whereas exchangeable aluminum determined L.kaempferi and L.olgensis distribution.Under future climate scenarios,habitat areas show divergent trajectories-L.principis-rupprechtii maximum gains 5.1%under SSP126,while L.kaempferi maximum expands 15.1%.Conversely,SSP585 triggered a 3.7% decline for L.gmelinii during the 2040s−2100s,and L.olgensis faces a net reduction to 0.4% by 2100s despite transient gains.Spatially,three species(L.kaempferi,L.gmelinii,L.olgensis)shifted northward,while L.principis-rupprechtii migrated northwest.All species distribution ascended altitudinally reflecting thermal adaptation strategies.These multidimensional insights enable targeted species selection for climate-resilient afforestation and underscore the need for soil-inclusive management planning.展开更多
Currently,there are a limited number of dynamic models available for braided composite plates with large overall motions,despite the incorporation of three-dimensional(3D)braided composites into rotating blade compone...Currently,there are a limited number of dynamic models available for braided composite plates with large overall motions,despite the incorporation of three-dimensional(3D)braided composites into rotating blade components.In this paper,a dynamic model of 3D 4-directional braided composite thin plates considering braiding directions is established.Based on Kirchhoff's plate assumptions,the displacement variables of the plate are expressed.By incorporating the braiding directions into the constitutive equation of the braided composites,the dynamic model of the plate considering braiding directions is obtained.The effects of the speeds,braiding directions,and braided angles on the responses of the plate with fixed-axis rotation and translational motion,respectively,are investigated.This paper presents a dynamic theory for calculating the deformation of 3D braided composite structures undergoing both translational and rotational motions.It also provides a simulation method for investigating the dynamic behavior of non-isotropic material plates in various applications.展开更多
The identification of rock mass discontinuities is critical for rock mass characterization.While high-resolution digital outcrop models(DOMs)are widely used,current digital methods struggle to generalize across divers...The identification of rock mass discontinuities is critical for rock mass characterization.While high-resolution digital outcrop models(DOMs)are widely used,current digital methods struggle to generalize across diverse geological settings.Large-scale models(LSMs),with vast parameter spaces and extensive training datasets,excel in solving complex visual problems.This study explores the potential of using one such LSM,Segment anything model(SAM),to identify facet-type discontinuities across several outcrops via interactive prompting.The findings demonstrate that SAM effectively segments two-dimensional(2D)discontinuities,with its generalization capability validated on a dataset of 2426 identified discontinuities across 170 outcrops.The model achieves 0.78 mean IoU and 0.86 average precision using 11-point prompts.To extend to three dimensions(3D),a framework integrating SAM with Structure-from-Motion(SfM)was proposed.By utilizing the inherent but often overlooked relationship between image pixels and point clouds in SfM,the identification process was simplified and generalized across photogrammetric devices.Benchmark studies showed that the framework achieved 0.91 average precision,identifying 87 discontinuities in Dataset-3D.The results confirm its high precision and efficiency,making it a valuable tool for data annotation.The proposed method offers a practical solution for geological investigations.展开更多
The global demand for in vitro respiratory airway models has surged due to the coronavirus disease 2019(COVID-19)pandemic.Current state-of-the-art models use polymer membranes to separate epithelial cells from other c...The global demand for in vitro respiratory airway models has surged due to the coronavirus disease 2019(COVID-19)pandemic.Current state-of-the-art models use polymer membranes to separate epithelial cells from other cell types,creating a nonphysiological barrier.In this study,we applied three-dimensional(3D)printing and bioprinting to develop an in vitro model where endothelial and epithelial cells were in direct contact,mimicking their natural arrangement.This proof-ofconcept model includes a culture chamber,with an endothelial bioink printed and perfused through an epithelial channel.In silico simulations of the air velocity within the channel revealed shear stress values ranging from 0.13 to 0.39 Pa,aligning with the desired in vivo shear stress observed in the bronchi regions(0.1–0.4 Pa).Biomechanical movements during resting breathing were mimicked by incorporating a textile mesh positioned away from the cell–cell interface.The epithelial channel demonstrated a capacity for compression and expansion of up to−14.7%and+6.4%,respectively.Microscopic images showed that the epithelial cells formed a uniform monolayer within the lumen of the channel close to the bioprinted endothelial cells.Our novel model offers a valuable tool for future research into respiratory diseases and potential treatments under conditions closely mimicking those in the lung.展开更多
The acetylpolyamine oxidase(APAO),spermine oxidase(SMO),and spermidine/spermine N1-acetyltransferase(SSAT)are pivotal enzymes in polyamine metabolism,exerting direct influence on polyamine homeostasis regulation.Dysfu...The acetylpolyamine oxidase(APAO),spermine oxidase(SMO),and spermidine/spermine N1-acetyltransferase(SSAT)are pivotal enzymes in polyamine metabolism,exerting direct influence on polyamine homeostasis regulation.Dysfunctions in these enzymes are intricately linked to inflammatory diseases and cancers.Establishing their three-dimensional structures is essential for exploring enzymatic catalytic mechanisms and designing inhibitors at the atomic level.This article primarily assesses the precision of AlphaFold2 and molecular dynamics simulations in determining the three-dimensional structures of these enzymes,utilizing protein conformation rationality assessment,residue correlation matrix,and other techniques.This provides robust models for subsequent polyamine catabolic metabolism calculations and offers valuable insights for modeling proteins that have yet to acquire crystal structures.展开更多
3D model classification has emerged as a significant research focus in computer vision.However,traditional convolutional neural networks(CNNs)often struggle to capture global dependencies across both height and width ...3D model classification has emerged as a significant research focus in computer vision.However,traditional convolutional neural networks(CNNs)often struggle to capture global dependencies across both height and width dimensions simultaneously,leading to limited feature representation capabilities when handling complex visual tasks.To address this challenge,we propose a novel 3D model classification network named ViT-GE(Vision Transformer with Global and Efficient Attention),which integrates Global Grouped Coordinate Attention(GGCA)and Efficient Channel Attention(ECA)mechanisms.Specifically,the Vision Transformer(ViT)is employed to extract comprehensive global features from multi-view inputs using its self-attention mechanism,effectively capturing 3D shape characteristics.To further enhance spatial feature modeling,the GGCA module introduces a grouping strategy and global context interactions.Concurrently,the ECA module strengthens inter-channel information flow,enabling the network to adaptively emphasize key features and improve feature fusion.Finally,a voting mechanism is adopted to enhance classification accuracy,robustness,and stability.Experimental results on the ModelNet10 dataset demonstrate that our method achieves a classification accuracy of 93.50%,validating its effectiveness and superior performance.展开更多
The Yishu fault zone in Shandong Province,China,exhibits favorable conditions for medium-and high-temperature geothermal storage.However,its geothermal occurrence patterns and heat storage model remain unclear.Recogni...The Yishu fault zone in Shandong Province,China,exhibits favorable conditions for medium-and high-temperature geothermal storage.However,its geothermal occurrence patterns and heat storage model remain unclear.Recognizing the importance of deep heat sources and heat channels in unraveling the formation mechanisms of medium-and high-temperature geothermal systems,we conducted a magnetotelluric survey along the Yishu fault zone,which contained 10 survey lines and 119 usable points.Using two-dimensional and three-dimensional nonlinear conjugate gradient inversion,the deep electrical structure was obtained,and the three-dimensional geothermal reservoir model in the study area was constructed for the first time.The results show that the deep low-resistance anomaly in the Yishu fault zone moves upward through the channel with slightly higher resistivity,forming a relatively low-resistance layer and a low-resistance layer in the shallow part,corresponding to the heat source,thermal conduction fault,heat reservoir,and overburden layer,respectively.The fault structure primarily controls regional geothermal anomalies,influencing atmospheric precipitation,surface water infiltration,and geothermal water migration pathways.The results of this study have a certain guiding significance for the study of the formation mechanism and distribution law of geothermal resources in the middle and deep strata of the Yishu fault zone.Additionally,the results provide valuable insights for the exploration and assessment of geothermal resources in the area.展开更多
Satellite Component Layout Optimization(SCLO) is crucial in satellite system design.This paper proposes a novel Satellite Three-Dimensional Component Assignment and Layout Optimization(3D-SCALO) problem tailored to en...Satellite Component Layout Optimization(SCLO) is crucial in satellite system design.This paper proposes a novel Satellite Three-Dimensional Component Assignment and Layout Optimization(3D-SCALO) problem tailored to engineering requirements, aiming to optimize satellite heat dissipation while considering constraints on static stability, 3D geometric relationships between components, and special component positions. The 3D-SCALO problem is a challenging bilevel combinatorial optimization task, involving the optimization of discrete component assignment variables in the outer layer and continuous component position variables in the inner layer,with both influencing each other. To address this issue, first, a Mixed Integer Programming(MIP) model is proposed, which reformulates the original bilevel problem into a single-level optimization problem, enabling the exploration of a more comprehensive optimization space while avoiding iterative nested optimization. Then, to model the 3D geometric relationships between components within the MIP framework, a linearized 3D Phi-function method is proposed, which handles non-overlapping and safety distance constraints between cuboid components in an explicit and effective way. Subsequently, the Finite-Rectangle Method(FRM) is proposed to manage 3D geometric constraints for complex-shaped components by approximating them with a finite set of cuboids, extending the applicability of the geometric modeling approach. Finally, the feasibility and effectiveness of the proposed MIP model are demonstrated through two numerical examples"and a real-world engineering case, which confirms its suitability for complex-shaped components and real engineering applications.展开更多
Long-duration energy storage has become critical for renewable energy integration.While redox flow batteries,especially vanadium-based systems,are scaling up in capacity,their performance at the stack level remains in...Long-duration energy storage has become critical for renewable energy integration.While redox flow batteries,especially vanadium-based systems,are scaling up in capacity,their performance at the stack level remains insufficiently optimized,demanding more profound mechanistic studies and engineering refinements.To address the difficulties in resolving the flow inhomogeneity at the stack scale,this study establishes a multi-physics field coupling model and analyzes the pressure distributions,flow rate differences,active substance concentration,and electrochemical characteristics.The results show that the uneven cell pressure distribution is a key factor affecting the consistency of the system performance,and the increase in the flow rate improves the reactant homogeneity,with both the average concentration and the uniformity factor increasing with the flow rate.In contrast,high current densities lead to an increased imbalance between electrochemical depletion and reactant replenishment,resulting in a significant decrease in reactant concentration in the under-ribs region.In addition,a higher flow rate can expand the high-current-density region where the stack operates efficiently.This study provides a theoretical basis for optimizing the design of the stack components.展开更多
A numerical investigation on the effectiveness of the actuator disc method in producing the interactions of multiple tidal stream devices via the 3D-RANS finite element model Telemac3D is explored. The methodology for...A numerical investigation on the effectiveness of the actuator disc method in producing the interactions of multiple tidal stream devices via the 3D-RANS finite element model Telemac3D is explored. The methodology for the implementation of the source term to represent an array of 20 m rotor diameter turbines deployed in an idealized channel is reviewed and discussed in detail. Flow interactions between multiple turbines are investigated for a single row arrangement with only two turbines and a two row arrangement containing three turbines. The results demonstrate that the non-hydrostatic solver shows better agreement when validated against published experimental data. Notably,the mesh density at the device location can strongly influence the simulated thrust from the disc. Although the actuator disc model can generally replicate the wake interactions well, the results indicate that it cannot accurately characterize the flow for regions with high turbulences. While a model setup with the largest lateral spacing(1.5D) demonstrates excellent agreement with the experimental data, the 0.5D model(smallest gap) deviates by up to 25%. These findings demonstrate the effectiveness of the applied source term in reproducing the wake profile, which is comparable with the published data, and highlight the inherent nature of the RANS and actuator disc models.展开更多
Constructing an in vitro vascularized liver tissue model that closely simulates the human liver is crucial for promoting cell proliferation,mimicking physiological heterogeneous structures,and recreating the cellular ...Constructing an in vitro vascularized liver tissue model that closely simulates the human liver is crucial for promoting cell proliferation,mimicking physiological heterogeneous structures,and recreating the cellular microenvironment.However,the layer-by-layer printing method is significantly constrained by the rheological properties of the bioink,making it challenging to form complex three-dimensional vascular structures in low-viscosity soft materials.To overcome this limitation,we developed a cross-linkable biphasic embedding medium by mixing low-viscosity biomaterials with gelatin microgel.This medium possesses yield stress and self-healing properties,facilitating efficient and continuous three-dimensional shaping of sacrificial ink within it.By adjusting the printing speed,we controlled the filament diameter,achieving a range from 250μm to 1000μm,and ensuring precise control over ink deposition locations and filament shapes.Using the in situ endothelialization method,we constructed complex vascular structures and ensured close adhesion between hepatocytes and endothelial cells.In vitro experiments demonstrated that the vascularized liver tissue model exhibited enhanced protein synthesis and metabolic function compared to mixed liver tissue.We also investigated the impact of varying vascular densities on liver tissue function.Transcriptome sequencing revealed that liver tissues with higher vascular density exhibited upregulated gene expression in metabolic and angiogenesis-related pathways.In summary,this method is adaptable to various materials,allowing the rheological properties of the supporting bath and the tissue's porosity to be modified using microgels,thus enabling precise regulation of the liver tissue microenvironment.Additionally,it facilitates the rapid construction of three-dimensional vascular structures within liver tissue.The resulting vascularized liver tissue model exhibits enhanced biological functionality,opening new opportunities for biomedical applications.展开更多
Typically,seat or floor acceleration is used to evaluate the ride comfort of a high-speed train.However,the dynamic performance of the human body significantly differs from that of the floor.Therefore,using the car bo...Typically,seat or floor acceleration is used to evaluate the ride comfort of a high-speed train.However,the dynamic performance of the human body significantly differs from that of the floor.Therefore,using the car body floor and seat accelerations to calculate the ride comfort index of a high-speed train may not reflect the true feelings of passengers.In this study,a 3D human-seat-vehicle-track coupling model was established to investigate the ride comfort of highspeed train passengers.The seated human model,which considers the longitudinal,lateral,vertical,pitching,yawing,and rolling motions,comprises the head,upper torso,lower torso,pelvis,thighs,and shanks.The model parameters were determined using multi-axis excitation measurement data based on a genetic algorithm.Subsequently,the applicability of the small-angle assumption and natural modes of the human model is analyzed.Using the coupling system model,the vibration characteristics of the human-seat interaction surface were analyzed.The ride comfort of the high-speed train and human body dynamic performance were analyzed under normal conditions,track geometric irregularities and train meeting conditions.The results showed that the passenger seats in the front and rear rows adjacent to the window had a higher acceleration value than the others.The human backrest and seat pad connection points have higher vibration amplitudes than the car body floor in the human-sensitive frequency range,indicating that using the acceleration values on the floor may underestimate the discomfort of passengers.The ride comfort of high-speed trains diminishes in the presence of track geometric irregularities and when trains pass each other.When the excitation frequency of track geometry irregularities approached the natural frequency of the human-seat-vehicle system,ride comfort in high-speed trains decreased significantly.Moreover,using seat acceleration to evaluate passenger ride comfort overlooks the vibration characteristics of the human body.The transient aerodynamic force generated when the train meets can cause a larger car body roll and lateral motion at 2 Hz,which,in turn,decreases the passenger ride comfort.This study presents a detailed human-seat-vehicle-track coupling system that can reflect a passenger’s dynamic performance under complex operating conditions.展开更多
The development of digital twins for geotechnical structures necessitates the real-time updates of threedimensional(3D)virtual models(e.g.numerical finite element method(FEM)model)to accurately predict time-varying ge...The development of digital twins for geotechnical structures necessitates the real-time updates of threedimensional(3D)virtual models(e.g.numerical finite element method(FEM)model)to accurately predict time-varying geotechnical responses(e.g.consolidation settlement)in a 3D spatial domain.However,traditional 3D numerical model updating approaches are computationally prohibitive and therefore difficult to update the 3D responses in real time.To address these challenges,this study proposes a novel machine learning framework called sparse dictionary learning(T-3D-SDL)for real-time updating of time-varying 3D geotechnical responses.In T-3D-SDL,a concerned dataset(e.g.time-varying 3D settlement)is approximated as a linear superposition of dictionary atoms generated from 3D random FEM analyses.Field monitoring data are then used to identify non-trivial atoms and estimate their weights within a Bayesian framework for model updating and prediction.The proposed approach enables the real-time update of temporally varying settlements with a high 3D spatial resolution and quantified uncertainty as field monitoring data evolve.The proposed approach is illustrated using an embankment construction project.The results show that the proposed approach effectively improves settlement predictions along temporal and 3D spatial dimensions,with minimal latency(e.g.within minutes),as monitoring data appear.In addition,the proposed approach requires only a reasonably small number of 3D FEM model evaluations,avoids the use of widely adopted yet often criticized surrogate models,and effectively addresses the limitations(e.g.computational inefficiency)of existing 3D model updating approaches.展开更多
Scalar CSAMT is only suitable for measurements in one and two dimensions perpendicular to geological structures. For complex 3D geoelectric structure, tensor CSAMT is more suitable. In this paper, we discuss 3D tensor...Scalar CSAMT is only suitable for measurements in one and two dimensions perpendicular to geological structures. For complex 3D geoelectric structure, tensor CSAMT is more suitable. In this paper, we discuss 3D tensor CSAMT forward modeling using the vector finite-element method. To verify the feasibility of the algorithm, we calculate the electric field, magnetic field, and tensor impedance of the 3D CSAMT far-zone field in layered media and compare them with theoretical solutions. In addition, a three-dimensional anomaly in half-space is also simulated, and the response characteristics of the impedance tensor and the apparent resistivity and impedance phase are analyzed. The results suggest that the vector finite-element method produces high-precision electromagnetic field and impedance tensor data, satisfies the electric field discontinuity, and does not require divergence correction using the vector finite-element method.展开更多
基金supported by the National Natural Science Foundation of China (51075147)
文摘To study the rock deformation with three- dimensional model under rolling forces of disc cutter, by car- rying out the circular-grooving test with disc cutter rolling around on the rock, the rock mechanical behavior under rolling disc cutter is studied, the mechanical model of disc cutter rolling around the groove is established, and the the- ory of single-point and double-angle variables is proposed. Based on this theory, the physics equations and geometric equations of rock mechanical behavior under disc cutters of tunnel boring machine （TBM） are studied, and then the bal- ance equations of interactive forces between disc cutter and rock are established. Accordingly, formulas about normal force, rolling force and side force of a disc cutter are de- rived, and their validity is studied by tests. Therefore, a new method and theory is proposed to study rock- breaking mech- anism of disc cutters.
基金funded by Prime Minister’s Research Fellowship(PMRF),grant number SB22230924OEPMRF008608.
文摘A hybrid model combining Fully Non-Linear Potential Flow Theory(FNPT)based on the Finite Element Method(FEM)and the Unified Navier-Stokes equation,using the 3D Improved Meshless Local Petrov Galerkin method with Rankine Source(IMLPG_R),is developed to study wave interactions with a porous layer.In previous studies,the above formulations are applied to wave interaction with fixed cylindrical structures.The present study extends this framework by integrating a unified governing equation within the hybrid modeling approach to capture the dynamics of wave interaction with porous media.The porous layers are employed to replicate the wave-dissipating behavior of the structure.A weak coupling strategy is implemented within a designated buffer zone,wherein field variables from the 2D Fully Nonlinear Potential Theory(FNPT)simulations are transferred to the 3D Improved Moving Least Squares-based Petrov-Galerkin(IMLPG_R)model at each time step.This domain decomposition significantly reduces computational cost compared to a full 3D simulation by partitioning the domain into two subregions:the FNPT domain representing the far-field without structures,and the IMLPG_R domain encompassing the porous region.The Unified Navier-Stokes formulation is extended by incorporating additional drag forces governed by Darcy’s law to model the resistance introduced by the porous medium.A stationary background node framework is utilized for interpolation by fluid particles at each time step to accommodate the porous representation.To enhance numerical stability and accuracy,particularly in the presence of sloping boundaries,the Particle Shifting Technique(PST)is integrated into the IMLPG_R model.This implementation involves a modified version of the PST algorithm,where key parameters such as the weight function,velocity ratio,and radius of influence are optimized for IMLPG_R.This is the first time the application of 3D IMLPG_R for porous structure has been reported.Further,the model is subsequently validated against experimental data.
基金supported by the Canadian Institutes of Health Research(DFD-181599)the National Institutes of Health(T32AG058527)to RJB and R0190106435 to VM.
文摘Neurodegenerative disorders represent an increasingly pertinent public health crisis.As a greater proportion of the population ages,neurodegenerative disorders and other diseases of aging place undue burdens on patients,caregivers,and healthcare workers.Alzheimer’s disease(AD)and Parkinson’s disease represent the two most common neurodegenerative disorders in the population,affecting over 65 million people,worldwide.
基金financially supported by the Ministry of Science and Technology of China(Nos.2022YFF0801201,2021YFC2900300)the National Natural Science Foundation of China(Nos.41872245,U1911202)the Guangdong Basic and Applied Basic Research Foundation(No.2020A1515010666)。
文摘To comprehensively utilize the valuable geological map,exploration profile,borehole,and geochemical logging data and the knowledge on the formation of the Jinshan Ag-Au deposit for forecasting the exploration targets of concealed ore bodies,three-dimensional Mineral Prospectivity Modeling(MPM)of the deposit has been conducted using the weights-of-evidence(WofE)method.Conditional independence between evidence layers was tested,and the outline results using the prediction-volume(P-V)and Student's t-statistic methods for delineating favorable mineralization areas from continuous posterior probability map were critically compared.Four exploration targets delineated ultimately by the Student's t-statistic method for the discovery of minable ore bodies in each of the target areas were discussed in detail.The main conclusions include:(1)three-dimensional modeling of a deposit using multi-source reconnaissance data is useful for MPM in interpreting their relationships with known ore bodies;(2)WofE modeling can be used as a straightforward tool for integrating deposit model and reconnaissance data in MPM;(3)the Student's t-statistic method is more applicable in binarizing the continuous prospectivity map for exploration targeting than the PV approach;and(4)two target areas within high potential to find undiscovered ore bodies were diagnosed to guide future near-mine exploration activities of the Jinshan deposit.
文摘Background:Traditional imaging approaches to keratoconus(KCN)have thus far failed to produce a standardized approach for diagnosis.While many diagnostic modalities and metrics exist,none have proven robust enough to be considered a gold standard.This study aims to introduce novel metrics to differentiate between KCN and healthy corneas using three-dimensional(3D)measurements of surface area and volume.Methods:This retrospective observational study examined KCN patients along with healthy control patients between the ages of 20 and 79 years old at the University of Maryland,Baltimore.The selected patients underwent a nine-line raster scan anterior segment optical coherence tomography(AS-OCT).ImageJ was used to determine the central 6 mm of each image and each corneal image was then divided into six 1 mm segments.Free-D software was then used to render the nine different images into a 3D model to calculate corneal surface area and volume.A two-tailed Mann-Whitney test was used to assess statistical significance when comparing these subsets.Results:Thirty-three eyes with KCN,along with 33 healthy control,were enrolled.There were statistically significant differences between the healthy and KCN groups in the metric of anterior corneal surface area(13.927 vs.13.991 mm^(2),P=0.046),posterior corneal surface area(14.045 vs.14.173 mm^(2),P<0.001),and volume(8.430 vs.7.773 mm3,P<0.001)within the central 6 mm.Conclusions:3D corneal models derived from AS-OCT can be used to measure anterior corneal surface area,posterior corneal surface area,and corneal volume.All three parameters are statistically different between corneas with KCN and healthy corneas.Further study and application of these parameters may yield new methodologies for the detection of KCN.
文摘Background:Successful liver resection in oncologic surgery depends on safety,precision,and efficacy,all of which require a thorough understanding of liver anatomy.Contrast-enhanced computed tomography(CT)-generated three-dimensional(3D)models have been proposed as a valuable tool to enhance this understanding.However,a systematic comparison of different display modalities across professional groups has not yet been performed.Methods:In this prospective,monocentric randomized trial,we compared high-resolution twodimensional(2D)CT images of liver malignancies with their corresponding standardized,non-colored 3D virtual and printed models in facilitating anatomical and spatial understanding as well as surgical decision-making.A total of 91 participants,including 40 surgeons,10 radiologists,and 41 students,evaluated six clinical cases(three centrally and three peripherally located liver malignancies).Each participant assessed one central and one peripheral case per display modality,presented in a random order.Results:Compared to 2D CT images,both 3D virtual and printed models significantly improved the identification of tumor location(P<0.001),enhanced the comprehension of spatial relationships with adjacent liver and portal veins(P<0.001 and P=0.019,respectively),and facilitated clinical decisionmaking(P<0.001).No significant difference was observed between virtual and printed models in terms of effectiveness.Within the different groups,surgeons and students,but not radiologists,more accurately identified tumor location and spatial relationships with adjacent liver and portal veins using 3D models.Subjectively,most surgeons and students preferred 3D printed models over virtual models and 2D CT images.Conclusions:This study demonstrated that standardized,non-colored 3D virtual and printed models equally help preoperative anatomical understanding and decision-making,particularly for surgeons and students.By isolating the influence of display modality,our findings clarify prior inconsistent results and support the integration of cost-effective 3D visualization by applying virtual models into surgical planning and education.Preference for printed models despite comparable efficacy highlights the importance of user-centered implementation strategies.
基金supported by the National Key Research and Development Program of China(2022YFD2200501).
文摘Climate warming is significantly altering the distribution of tree species,which holds crucial implications for China’s Larix species as they are important afforestation efforts.Understanding their optimal habitats and environmental constraints is vital for predicting range shifts and guiding adaptive forest management.Previous studies prioritized changing climate impacts on horizontal range shifts of Larix,neglecting the influence of soil factors and range shift along altitudinal gradients.To address this,we applied an optimized MaxEnt model to assess current and future SSP126/SSP585 scenarios,three-dimensional habitat suitability(latitude,longitude,altitude)for four major Larix species(L.principis-rupprechtii,L.gmelinii,L.kaempferi,L.olgensis),while identifying key environmental drivers.Our results indicate that elevation and extreme moisture conditions universally constrain their distribution.Soil chemistry properties exhibited species-specific influences:cation exchange capacity critically shaped L.principis-rupprechtii and L.gmelinii ranges,whereas exchangeable aluminum determined L.kaempferi and L.olgensis distribution.Under future climate scenarios,habitat areas show divergent trajectories-L.principis-rupprechtii maximum gains 5.1%under SSP126,while L.kaempferi maximum expands 15.1%.Conversely,SSP585 triggered a 3.7% decline for L.gmelinii during the 2040s−2100s,and L.olgensis faces a net reduction to 0.4% by 2100s despite transient gains.Spatially,three species(L.kaempferi,L.gmelinii,L.olgensis)shifted northward,while L.principis-rupprechtii migrated northwest.All species distribution ascended altitudinally reflecting thermal adaptation strategies.These multidimensional insights enable targeted species selection for climate-resilient afforestation and underscore the need for soil-inclusive management planning.
基金Project supported by the National Natural Science Foundation of China(Nos.12372071 and 12372070)the Aeronautical Science Fund of China(No.2022Z055052001)the Foundation of China Scholarship Council(No.202306830079)。
文摘Currently,there are a limited number of dynamic models available for braided composite plates with large overall motions,despite the incorporation of three-dimensional(3D)braided composites into rotating blade components.In this paper,a dynamic model of 3D 4-directional braided composite thin plates considering braiding directions is established.Based on Kirchhoff's plate assumptions,the displacement variables of the plate are expressed.By incorporating the braiding directions into the constitutive equation of the braided composites,the dynamic model of the plate considering braiding directions is obtained.The effects of the speeds,braiding directions,and braided angles on the responses of the plate with fixed-axis rotation and translational motion,respectively,are investigated.This paper presents a dynamic theory for calculating the deformation of 3D braided composite structures undergoing both translational and rotational motions.It also provides a simulation method for investigating the dynamic behavior of non-isotropic material plates in various applications.
基金support in dataset preparation.This study was funded by National Natural Science Foundation of China(Nos.42422704 and 52379109)Opening the fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)(No.SKLGP2024K028)Science and Technology Research and Design Projects of China State Construction Engineering Corporation Ltd.(No.CSCEC-2024-Q-68).
文摘The identification of rock mass discontinuities is critical for rock mass characterization.While high-resolution digital outcrop models(DOMs)are widely used,current digital methods struggle to generalize across diverse geological settings.Large-scale models(LSMs),with vast parameter spaces and extensive training datasets,excel in solving complex visual problems.This study explores the potential of using one such LSM,Segment anything model(SAM),to identify facet-type discontinuities across several outcrops via interactive prompting.The findings demonstrate that SAM effectively segments two-dimensional(2D)discontinuities,with its generalization capability validated on a dataset of 2426 identified discontinuities across 170 outcrops.The model achieves 0.78 mean IoU and 0.86 average precision using 11-point prompts.To extend to three dimensions(3D),a framework integrating SAM with Structure-from-Motion(SfM)was proposed.By utilizing the inherent but often overlooked relationship between image pixels and point clouds in SfM,the identification process was simplified and generalized across photogrammetric devices.Benchmark studies showed that the framework achieved 0.91 average precision,identifying 87 discontinuities in Dataset-3D.The results confirm its high precision and efficiency,making it a valuable tool for data annotation.The proposed method offers a practical solution for geological investigations.
基金supported by the Volkswagen Foundation(Grant No.Az 99078 to DDC,ALT,and MT)funded by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany’s Excellence Strategy–2082/1–390761711(to DDC)part of the research training group GRK 2415–Mechanobiology in Epithelial 3D Tissue Constructs(project number 363055819,to ALT and SJ).
文摘The global demand for in vitro respiratory airway models has surged due to the coronavirus disease 2019(COVID-19)pandemic.Current state-of-the-art models use polymer membranes to separate epithelial cells from other cell types,creating a nonphysiological barrier.In this study,we applied three-dimensional(3D)printing and bioprinting to develop an in vitro model where endothelial and epithelial cells were in direct contact,mimicking their natural arrangement.This proof-ofconcept model includes a culture chamber,with an endothelial bioink printed and perfused through an epithelial channel.In silico simulations of the air velocity within the channel revealed shear stress values ranging from 0.13 to 0.39 Pa,aligning with the desired in vivo shear stress observed in the bronchi regions(0.1–0.4 Pa).Biomechanical movements during resting breathing were mimicked by incorporating a textile mesh positioned away from the cell–cell interface.The epithelial channel demonstrated a capacity for compression and expansion of up to−14.7%and+6.4%,respectively.Microscopic images showed that the epithelial cells formed a uniform monolayer within the lumen of the channel close to the bioprinted endothelial cells.Our novel model offers a valuable tool for future research into respiratory diseases and potential treatments under conditions closely mimicking those in the lung.
基金National Natural Science Foundation of China(22073023)Natural Science Foundation of Henan Province(242300421134)+1 种基金the Young Backbone Teacher in Colleges and Universities of Henan Province(2021GGJS020)Foundation of State Key Laboratory of Antiviral Drugs。
文摘The acetylpolyamine oxidase(APAO),spermine oxidase(SMO),and spermidine/spermine N1-acetyltransferase(SSAT)are pivotal enzymes in polyamine metabolism,exerting direct influence on polyamine homeostasis regulation.Dysfunctions in these enzymes are intricately linked to inflammatory diseases and cancers.Establishing their three-dimensional structures is essential for exploring enzymatic catalytic mechanisms and designing inhibitors at the atomic level.This article primarily assesses the precision of AlphaFold2 and molecular dynamics simulations in determining the three-dimensional structures of these enzymes,utilizing protein conformation rationality assessment,residue correlation matrix,and other techniques.This provides robust models for subsequent polyamine catabolic metabolism calculations and offers valuable insights for modeling proteins that have yet to acquire crystal structures.
基金funded by the project supported by the Heilongjiang Provincial Natural Science Foundation of China(Grant Number LH2022F030).
文摘3D model classification has emerged as a significant research focus in computer vision.However,traditional convolutional neural networks(CNNs)often struggle to capture global dependencies across both height and width dimensions simultaneously,leading to limited feature representation capabilities when handling complex visual tasks.To address this challenge,we propose a novel 3D model classification network named ViT-GE(Vision Transformer with Global and Efficient Attention),which integrates Global Grouped Coordinate Attention(GGCA)and Efficient Channel Attention(ECA)mechanisms.Specifically,the Vision Transformer(ViT)is employed to extract comprehensive global features from multi-view inputs using its self-attention mechanism,effectively capturing 3D shape characteristics.To further enhance spatial feature modeling,the GGCA module introduces a grouping strategy and global context interactions.Concurrently,the ECA module strengthens inter-channel information flow,enabling the network to adaptively emphasize key features and improve feature fusion.Finally,a voting mechanism is adopted to enhance classification accuracy,robustness,and stability.Experimental results on the ModelNet10 dataset demonstrate that our method achieves a classification accuracy of 93.50%,validating its effectiveness and superior performance.
文摘The Yishu fault zone in Shandong Province,China,exhibits favorable conditions for medium-and high-temperature geothermal storage.However,its geothermal occurrence patterns and heat storage model remain unclear.Recognizing the importance of deep heat sources and heat channels in unraveling the formation mechanisms of medium-and high-temperature geothermal systems,we conducted a magnetotelluric survey along the Yishu fault zone,which contained 10 survey lines and 119 usable points.Using two-dimensional and three-dimensional nonlinear conjugate gradient inversion,the deep electrical structure was obtained,and the three-dimensional geothermal reservoir model in the study area was constructed for the first time.The results show that the deep low-resistance anomaly in the Yishu fault zone moves upward through the channel with slightly higher resistivity,forming a relatively low-resistance layer and a low-resistance layer in the shallow part,corresponding to the heat source,thermal conduction fault,heat reservoir,and overburden layer,respectively.The fault structure primarily controls regional geothermal anomalies,influencing atmospheric precipitation,surface water infiltration,and geothermal water migration pathways.The results of this study have a certain guiding significance for the study of the formation mechanism and distribution law of geothermal resources in the middle and deep strata of the Yishu fault zone.Additionally,the results provide valuable insights for the exploration and assessment of geothermal resources in the area.
基金supported by the National Natural Science Foundation of China(No.92371206)the Postgraduate Scientific Research Innovation Project of Hunan Province,China(No.CX2023063).
文摘Satellite Component Layout Optimization(SCLO) is crucial in satellite system design.This paper proposes a novel Satellite Three-Dimensional Component Assignment and Layout Optimization(3D-SCALO) problem tailored to engineering requirements, aiming to optimize satellite heat dissipation while considering constraints on static stability, 3D geometric relationships between components, and special component positions. The 3D-SCALO problem is a challenging bilevel combinatorial optimization task, involving the optimization of discrete component assignment variables in the outer layer and continuous component position variables in the inner layer,with both influencing each other. To address this issue, first, a Mixed Integer Programming(MIP) model is proposed, which reformulates the original bilevel problem into a single-level optimization problem, enabling the exploration of a more comprehensive optimization space while avoiding iterative nested optimization. Then, to model the 3D geometric relationships between components within the MIP framework, a linearized 3D Phi-function method is proposed, which handles non-overlapping and safety distance constraints between cuboid components in an explicit and effective way. Subsequently, the Finite-Rectangle Method(FRM) is proposed to manage 3D geometric constraints for complex-shaped components by approximating them with a finite set of cuboids, extending the applicability of the geometric modeling approach. Finally, the feasibility and effectiveness of the proposed MIP model are demonstrated through two numerical examples"and a real-world engineering case, which confirms its suitability for complex-shaped components and real engineering applications.
基金supported by National Natural Science Foundation of China(No.524B2078,12426307,51906203)Guangdong Major Project of Basic and Applied Basic Research(2023B0303000002)+6 种基金Guangdong Basic and Applied Basic Research Foundation(2023B1515120005)Natural Science Foundation of Shenzhen(JCYJ20241202125327036,JCYJ20240813100103005)Shenzhen Engineering Research Center of Redox Flow Battery for Energy Storage(XMHT20230208003)Research Project on Medium-and Long-Duration Flow Battery Energy Storage Technology(2024KJTW0015)China Association for Science and Technology(OR2308010)High level of special funds(G03034K001)supported by the Center for Computational Science and Engineering at the Southern University of Science and Technology.
文摘Long-duration energy storage has become critical for renewable energy integration.While redox flow batteries,especially vanadium-based systems,are scaling up in capacity,their performance at the stack level remains insufficiently optimized,demanding more profound mechanistic studies and engineering refinements.To address the difficulties in resolving the flow inhomogeneity at the stack scale,this study establishes a multi-physics field coupling model and analyzes the pressure distributions,flow rate differences,active substance concentration,and electrochemical characteristics.The results show that the uneven cell pressure distribution is a key factor affecting the consistency of the system performance,and the increase in the flow rate improves the reactant homogeneity,with both the average concentration and the uniformity factor increasing with the flow rate.In contrast,high current densities lead to an increased imbalance between electrochemical depletion and reactant replenishment,resulting in a significant decrease in reactant concentration in the under-ribs region.In addition,a higher flow rate can expand the high-current-density region where the stack operates efficiently.This study provides a theoretical basis for optimizing the design of the stack components.
文摘A numerical investigation on the effectiveness of the actuator disc method in producing the interactions of multiple tidal stream devices via the 3D-RANS finite element model Telemac3D is explored. The methodology for the implementation of the source term to represent an array of 20 m rotor diameter turbines deployed in an idealized channel is reviewed and discussed in detail. Flow interactions between multiple turbines are investigated for a single row arrangement with only two turbines and a two row arrangement containing three turbines. The results demonstrate that the non-hydrostatic solver shows better agreement when validated against published experimental data. Notably,the mesh density at the device location can strongly influence the simulated thrust from the disc. Although the actuator disc model can generally replicate the wake interactions well, the results indicate that it cannot accurately characterize the flow for regions with high turbulences. While a model setup with the largest lateral spacing(1.5D) demonstrates excellent agreement with the experimental data, the 0.5D model(smallest gap) deviates by up to 25%. These findings demonstrate the effectiveness of the applied source term in reproducing the wake profile, which is comparable with the published data, and highlight the inherent nature of the RANS and actuator disc models.
基金the funding from the National Natural Science Foundation of China No.52275294the National Key Research and Development Program of China(No.2018YFA0703000)。
文摘Constructing an in vitro vascularized liver tissue model that closely simulates the human liver is crucial for promoting cell proliferation,mimicking physiological heterogeneous structures,and recreating the cellular microenvironment.However,the layer-by-layer printing method is significantly constrained by the rheological properties of the bioink,making it challenging to form complex three-dimensional vascular structures in low-viscosity soft materials.To overcome this limitation,we developed a cross-linkable biphasic embedding medium by mixing low-viscosity biomaterials with gelatin microgel.This medium possesses yield stress and self-healing properties,facilitating efficient and continuous three-dimensional shaping of sacrificial ink within it.By adjusting the printing speed,we controlled the filament diameter,achieving a range from 250μm to 1000μm,and ensuring precise control over ink deposition locations and filament shapes.Using the in situ endothelialization method,we constructed complex vascular structures and ensured close adhesion between hepatocytes and endothelial cells.In vitro experiments demonstrated that the vascularized liver tissue model exhibited enhanced protein synthesis and metabolic function compared to mixed liver tissue.We also investigated the impact of varying vascular densities on liver tissue function.Transcriptome sequencing revealed that liver tissues with higher vascular density exhibited upregulated gene expression in metabolic and angiogenesis-related pathways.In summary,this method is adaptable to various materials,allowing the rheological properties of the supporting bath and the tissue's porosity to be modified using microgels,thus enabling precise regulation of the liver tissue microenvironment.Additionally,it facilitates the rapid construction of three-dimensional vascular structures within liver tissue.The resulting vascularized liver tissue model exhibits enhanced biological functionality,opening new opportunities for biomedical applications.
基金Supported by National Natural Science Foundation of China(Grant No.U1934203)Research and Development Project of Science and Technology of China Railway Corporation(Grant No.P2023T002)。
文摘Typically,seat or floor acceleration is used to evaluate the ride comfort of a high-speed train.However,the dynamic performance of the human body significantly differs from that of the floor.Therefore,using the car body floor and seat accelerations to calculate the ride comfort index of a high-speed train may not reflect the true feelings of passengers.In this study,a 3D human-seat-vehicle-track coupling model was established to investigate the ride comfort of highspeed train passengers.The seated human model,which considers the longitudinal,lateral,vertical,pitching,yawing,and rolling motions,comprises the head,upper torso,lower torso,pelvis,thighs,and shanks.The model parameters were determined using multi-axis excitation measurement data based on a genetic algorithm.Subsequently,the applicability of the small-angle assumption and natural modes of the human model is analyzed.Using the coupling system model,the vibration characteristics of the human-seat interaction surface were analyzed.The ride comfort of the high-speed train and human body dynamic performance were analyzed under normal conditions,track geometric irregularities and train meeting conditions.The results showed that the passenger seats in the front and rear rows adjacent to the window had a higher acceleration value than the others.The human backrest and seat pad connection points have higher vibration amplitudes than the car body floor in the human-sensitive frequency range,indicating that using the acceleration values on the floor may underestimate the discomfort of passengers.The ride comfort of high-speed trains diminishes in the presence of track geometric irregularities and when trains pass each other.When the excitation frequency of track geometry irregularities approached the natural frequency of the human-seat-vehicle system,ride comfort in high-speed trains decreased significantly.Moreover,using seat acceleration to evaluate passenger ride comfort overlooks the vibration characteristics of the human body.The transient aerodynamic force generated when the train meets can cause a larger car body roll and lateral motion at 2 Hz,which,in turn,decreases the passenger ride comfort.This study presents a detailed human-seat-vehicle-track coupling system that can reflect a passenger’s dynamic performance under complex operating conditions.
基金supported by a grant from the Research Grant Council of Hong Kong Special Administrative Region(Project No.11207724).
文摘The development of digital twins for geotechnical structures necessitates the real-time updates of threedimensional(3D)virtual models(e.g.numerical finite element method(FEM)model)to accurately predict time-varying geotechnical responses(e.g.consolidation settlement)in a 3D spatial domain.However,traditional 3D numerical model updating approaches are computationally prohibitive and therefore difficult to update the 3D responses in real time.To address these challenges,this study proposes a novel machine learning framework called sparse dictionary learning(T-3D-SDL)for real-time updating of time-varying 3D geotechnical responses.In T-3D-SDL,a concerned dataset(e.g.time-varying 3D settlement)is approximated as a linear superposition of dictionary atoms generated from 3D random FEM analyses.Field monitoring data are then used to identify non-trivial atoms and estimate their weights within a Bayesian framework for model updating and prediction.The proposed approach enables the real-time update of temporally varying settlements with a high 3D spatial resolution and quantified uncertainty as field monitoring data evolve.The proposed approach is illustrated using an embankment construction project.The results show that the proposed approach effectively improves settlement predictions along temporal and 3D spatial dimensions,with minimal latency(e.g.within minutes),as monitoring data appear.In addition,the proposed approach requires only a reasonably small number of 3D FEM model evaluations,avoids the use of widely adopted yet often criticized surrogate models,and effectively addresses the limitations(e.g.computational inefficiency)of existing 3D model updating approaches.
基金supported by the National Natural Science Foundation of China(No.41104068)the Deep Exploration in China,Sino Probe-03-05
文摘Scalar CSAMT is only suitable for measurements in one and two dimensions perpendicular to geological structures. For complex 3D geoelectric structure, tensor CSAMT is more suitable. In this paper, we discuss 3D tensor CSAMT forward modeling using the vector finite-element method. To verify the feasibility of the algorithm, we calculate the electric field, magnetic field, and tensor impedance of the 3D CSAMT far-zone field in layered media and compare them with theoretical solutions. In addition, a three-dimensional anomaly in half-space is also simulated, and the response characteristics of the impedance tensor and the apparent resistivity and impedance phase are analyzed. The results suggest that the vector finite-element method produces high-precision electromagnetic field and impedance tensor data, satisfies the electric field discontinuity, and does not require divergence correction using the vector finite-element method.
