Yingqiong basin is a proven hydrocarbon-rich basin in South China Sea. There are a number of large exploration prospects in high temperature and over-pressured formations, especially in Yacheng Block of Qiongdongnan b...Yingqiong basin is a proven hydrocarbon-rich basin in South China Sea. There are a number of large exploration prospects in high temperature and over-pressured formations, especially in Yacheng Block of Qiongdongnan basin and Dongfang District of Yinggehai Basin. Owing to good exploration situation, we have already achieved proven geological reserves over 1000 × 108 m3. In recent years, a few drilled HPHT wells have confirmed that pressure predicted by conventional method was wildly inaccurate. From the view of regional stress, the accuracy of the pressure prediction will be substantially improved. Accurate pressure prediction and three-dimensional pressure modeling which are based on three-dimensional lithology modeling are the cornerstone to achieve exploration breakthrough. In this paper, the use of the triple constraint trend lithology model broke through the traditional method of seismic lithology prediction only by means of impedance threshold value. Compared with actual data and prediction, it confirms that three-dimensional pressure modeling method is reasonable and effective, and has a wide prospect of application.展开更多
The micro-riblet structures have been demonstrated effective in controlling the Total Pressure Loss(TPL)of aero-engine blades.However,due to the considerable scale gap between micro-texture and an actual aero-engine b...The micro-riblet structures have been demonstrated effective in controlling the Total Pressure Loss(TPL)of aero-engine blades.However,due to the considerable scale gap between micro-texture and an actual aero-engine blade,wind tunnel tests and numerical simulations with massive grids directly describing the global flow field are costly for aerodynamic evaluation.Furthermore,the fine micro surface structure brings unavoidable manufacturing errors,and the probability prediction contributes to gaining the confidence interval of the results.Therefore,a novel relay-based probabilistic model for multi-fidelity scenarios in the TPL prediction of a compressor cascade with micro-riblet surfaces is proposed to trade off accuracy and efficiency.Combined with the low-fidelity flow data generated by an aerodynamic solution strategy using the boundary surrogate model and the high-fidelity flow data from the experiment,the relay-based modeling has been achieved through knowledge transferring,and the confidence interval can be provided by the Gaussian Process Regression(GPR)model.The TPL of compressor cascades with micro-riblet surfaces under different surface structures at March number Ma=0.64,0.74,0.84 have been evaluated using the Relay-Based Probabilistic(RBP)model.The results illustrate that the RBP model could provide higher accuracy than the Single-Fidelity-Data-Driven(SFDD)prediction model,which show the promising potential of multi-fidelity scenarios data fusion in the aerodynamic evaluation of multi-scale configurations.展开更多
Hydraulic stimulation technology is widely employed to enhance the permeability of geothermal reservoirs.Nevertheless,accurately predicting hydraulic fracture propagation in complex geological conditions remains chall...Hydraulic stimulation technology is widely employed to enhance the permeability of geothermal reservoirs.Nevertheless,accurately predicting hydraulic fracture propagation in complex geological conditions remains challenging,thereby hindering the effective utilization of existing natural fractures.In this study,a phase field model was developed utilizing the finite element method to examine the influence of fluid presence,stress conditions,and natural fractures on the initiation and propagation of hydraulic fractures.The model employs Biot's poroelasticity theory to establish the coupling between the displacement field and the fluid field,while the phase field theory is applied to simulate fracture behavior.The results show that whenσ_(x0)/σ_(y0)<3 or qf<20 kg/(m^(3)·s),the presence of natural fractures can alter the original propagation direction of hydraulic fractures.Conversely,in the absence of these conditions,the propagation path of natural fractures is predominantly influenced by the initial stress field.Furthermore,based on the analysis of breakdown pressure and damage area,the optimal intersection angle between natural fractures and hydraulic fractures is determined to range from 45°to 60°.Finally,once a dominant channel forms,initiating and propagating hydraulic fractures in other directions becomes increasingly difficult,even in highly fractured areas.This method tackles the challenges of initiating and propagating hydraulic fractures in complex geological conditions,providing a theoretical basis for optimizing Enhanced Geothermal System(EGS)projects.展开更多
A three dimensional finite element program incorporating actually measured vertical tire-pavement contact pressure(TPCP) was utilized for modeling the mechanistic responses in asphalt concrete(AC) layers by simulating...A three dimensional finite element program incorporating actually measured vertical tire-pavement contact pressure(TPCP) was utilized for modeling the mechanistic responses in asphalt concrete(AC) layers by simulating various vehicle motions:stationary and non-stationary(i.e.in acceleration or deceleration mode).Analysis of the results indicated the following items.1) It is critical to use the vertical TPCP as the design control criteria for the tensile strains at the bottom of the AC layer when the base layer modulus is lower in magnitude(e.g.≤400 MPa);however,when the base layer modulus is higher in magnitude(e.g.≥7 000 MPa),the horizontal TPCP and the tensile strains in the X-direction at the surface of the AC layer should also be considered as part of the design response criteria.2) The definition of "overload" needs to be revised to include tire pressure over-inflation,i.e.,a vehicle should be considered to be overloaded if the wheel load exceeds the specification and/or the tire inflation pressure is higher than the specification.3) Light trucks have more structural impact on the strain responses and pavement design when the thickness of the surfacing AC layer is thinner(e.g.≤50 mm).4) The acceleration of a vehicle does not significantly impact the AC surface distresses such as rutting at the top of the upgrade slopes or intersections;however,vehicle deceleration can dramatically induce horizontal shear strains and consequently,aggravate shoving and rutting problems at the highway intersections.Evidently,these factors should be taken into account during mechanistic stress-strain modeling and structural design of asphalt pavements.展开更多
A novel fiber Bragg grating(FBG)sensor with three-dimensional(3D)fused deposition modeling(FDM)approach is proposed for effective stress measurement in soil mass.The three-diaphragm structure design is developed to me...A novel fiber Bragg grating(FBG)sensor with three-dimensional(3D)fused deposition modeling(FDM)approach is proposed for effective stress measurement in soil mass.The three-diaphragm structure design is developed to measure earth and water pressures simultaneously.The proposed transducer has advantages of small size,high sensitivity,low cost,immunity to electromagnetic interference and rapid prototyping.The working principle,design parameters,and manufacturing details are discussed.The proposed transducer was calibrated for earth and water pressures measurement by using weights and a specially designed pressure chamber,respectively.The calibration results showed that the wavelength of the transducer was proportional to the applied pressure.The sensitivity coefficients of the earth and water pressures were 12.633 nm/MPa and 6.282 nm/MPa,respectively.Repeated tests and error analysis demonstrated the excellent stability and accuracy of the earth and water pressure measurements.The performance of the proposed transducer was further verified by a model experimental test and numerical analysis,which indicated that the proposed transducer has great potential for practical applications.展开更多
High ground temperature and unloading disturbance have emerged as critical factors impacting the property of cemented gauge-fly ash backfill(CGFB).The characteristics of energy and damage in CGFB were analyzed under c...High ground temperature and unloading disturbance have emerged as critical factors impacting the property of cemented gauge-fly ash backfill(CGFB).The characteristics of energy and damage in CGFB were analyzed under conditions of high ground temperature and unloading by conducting triaxial unloading tests with different initial confining pressures on CGFB that had been cured at various temperatures.Based on dissipative energy,triaxial unloading confining pressure damage constitutive model of CGFB was constructed.It has been demonstrated that the ratio of elastic strain energy in CGFB decreases and the ratio of dissipated energy increases at the end of unloading increases under higher curing temperature.The change in the elastic energy consumption ratio curve of CGFB,which shifts from a gradual increase to a swift rise at a certain"inflection point",can be utilized as a criterion for evaluating the failure of the unloading strength of CGFB.The triaxial unloading damage constitutive model for CGFB divides the damage progression into three distinct phases:initial damage stage,accelerated damage development stage,and rapid damage growth stage.The research findings offer a theoretical foundation for evaluating the extent of damage to CGFB caused by the combined influences of elevated ground temperature and unloading.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
During fully mechanized caving mining of thick coal seams,a large amount of strain energy accumulates in the roof,especially when the roof is thick and hard,making it difficultfor the roof to collapse naturally.When t...During fully mechanized caving mining of thick coal seams,a large amount of strain energy accumulates in the roof,especially when the roof is thick and hard,making it difficultfor the roof to collapse naturally.When the roof eventually collapses,the accumulated energy is released instantaneously,exerting a strong impact on the roadway.To address this issue,we proposed the synergistic control method of directional comprehensive pressure relief and energy-absorbing support(PREA)for roadways with hard roofs.In this study,we developed a three-dimensional physical model test apparatus for roof cutting and pressure relief.The 122108 ventilation roadway at the Caojiatan Coal Mine,which has a thick and hard roof,was taken as the engineering example.We analyzed the evolution patterns of stress and displacement in both the stope and the roadway surrounding rocks under different schemes.The PREA reinforcement mechanism for the roadway was investigated through comparative model tests between the new and original methods.The results showed that,compared to the original method,the new method reduced surrounding rock stress by up to 60.4%,and the roadway convergence decreased by up to 52.1%.Based on these results,we proposed corresponding engineering recommendations,which can guide fieldreinforcement design and application.The results demonstrate that the PREA method effectively reduces stress and ensures the safety and stability of the roadway.展开更多
The pressure comfort of passengers and crew in high-speed trains faces significant challenges under alternating open-tunnel conditions.To better understand the mechanism of pressure transmission and control interior p...The pressure comfort of passengers and crew in high-speed trains faces significant challenges under alternating open-tunnel conditions.To better understand the mechanism of pressure transmission and control interior pressure fluctuations in high-altitude regions,this study develops an interior pressure fluctuation model.By establishing the frameworks of the non-ideal gas state equation and the polytropic process equation,gas heat transfer and mass transfer were expressed through the first law of thermodynamics and the continuity equation.Simulation results,evaluated by root mean square error,coefficient of determination,peak-to-peak error,and pressure change rate,show that the proposed model closely aligns with measured signals in both overall trends and local details.Data from various train types and tunnel scenarios further demonstrate the model's accuracy and practical applicability.This study provides a critical foundation for evaluating interior pressure comfort for high-speed trains in high-altitude regions.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
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
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
Salt caverns are widely used for energy storage.During gas storage,the internal gas pressure fluctuates cyclically in response to energy demand,making it essential to assess how these pressure variations affect rock d...Salt caverns are widely used for energy storage.During gas storage,the internal gas pressure fluctuates cyclically in response to energy demand,making it essential to assess how these pressure variations affect rock deformation.In this study,experiments were conducted under different cyclic gas pressure conditions to investigate this effect.The findings indicate that(1)the deformation process of salt rock can be segmented into three stages:the deceleration stage,the steady-state stage,and the acceleration stage.(2)When the axial pressure remains constant,both axial and radial deformations exhibit a stepwise increasing trend in response to cyclic gas pressure variations.Similarly,under axial graded loading,the deformations also demonstrate a progressive rise.By analyzing the deformation differences and model coefficient fluctuations within a single gas pressure cycle,it is found that radial deformation is higher sensitive to changes in cyclic gas pressure.(3)The axial deformation shows a stepwise increase,and the radial deformation showed a cyclic change with changing gas pressure.Therefore,the cyclic gas pressure influence factor α,axial loading influence factor β,and state variable σ^(*)are introduced to develop a viscoplastic ontological model that accounts for the impacts of cyclic gas pressure,confining pressure and axial stress.Validated by the deformation data,the new model can better fit both the axial deformation and the radial deformation of the three stages and has strong applicability and accuracy by changing only fewer parameters.The state variable rate shows the same stage as the deformation rate and residual strain of salt rock,which can better reflect the internal hardening of salt rock.展开更多
Coalbed methane(CBM)is a vital unconventional energy resource,and predicting its spatiotemporal pressure dynamics is crucial for efficient development strategies.This paper proposes a novel deep learningebased data-dr...Coalbed methane(CBM)is a vital unconventional energy resource,and predicting its spatiotemporal pressure dynamics is crucial for efficient development strategies.This paper proposes a novel deep learningebased data-driven surrogate model,AxialViT-ConvLSTM,which integrates AxialAttention Vision Transformer,ConvLSTM,and an enhanced loss function to predict pressure dynamics in CBM reservoirs.The results showed that the model achieves a mean square error of 0.003,a learned perceptual image patch similarity of 0.037,a structural similarity of 0.979,and an R^(2) of 0.982 between predictions and actual pressures,indicating excellent performance.The model also demonstrates strong robustness and accuracy in capturing spatialetemporal pressure features.展开更多
Coal dust explosions are severe safety accidents in coal mine production,posing significant threats to life and property.Predicting the maximum explosion pressure(Pm)of coal dust using deep learning models can effecti...Coal dust explosions are severe safety accidents in coal mine production,posing significant threats to life and property.Predicting the maximum explosion pressure(Pm)of coal dust using deep learning models can effectively assess potential risks and provide a scientific basis for preventing coal dust explosions.In this study,a 20-L explosion sphere apparatus was used to test the maximum explosion pressure of coal dust under seven different particle sizes and ten mass concentrations(Cdust),resulting in a dataset of 70 experimental groups.Through Spearman correlation analysis and random forest feature selection methods,particle size(D_(10),D_(20),D_(50))and mass concentration(Cdust)were identified as critical feature parameters from the ten initial parameters of the coal dust samples.Based on this,a hybrid Long Short-Term Memory(LSTM)network model incorporating a Multi-Head Attention Mechanism and the Sparrow Search Algorithm(SSA)was proposed to predict the maximum explosion pressure of coal dust.The results demonstrate that the SSA-LSTM-Multi-Head Attention model excels in predicting the maximum explosion pressure of coal dust.The four evaluation metrics indicate that the model achieved a coefficient of determination(R^(2)),root mean square error(RMSE),mean absolute percentage error(MAPE),and mean absolute error(MAE)of 0.9841,0.0030,0.0074,and 0.0049,respectively,in the training set.In the testing set,these values were 0.9743,0.0087,0.0108,and 0.0069,respectively.Compared to artificial neural networks(ANN),random forest(RF),support vector machines(SVM),particle swarm optimized-SVM(PSO-SVM)neural networks,and the traditional single-model LSTM,the SSA-LSTM-Multi-Head Attention model demonstrated superior generalization capability and prediction accuracy.The findings of this study not only advance the application of deep learning in coal dust explosion prediction but also provide robust technical support for the prevention and risk assessment of coal dust explosions.展开更多
Understanding the hydromechanical behavior and permeability stress sensitivity of hydraulic fractures is fundamental for geotechnical applications associated with fluid injection.This paper presents a three-dimensiona...Understanding the hydromechanical behavior and permeability stress sensitivity of hydraulic fractures is fundamental for geotechnical applications associated with fluid injection.This paper presents a three-dimensional(3D)benchmark model of a laboratory experiment on graywacke to examine the dynamic hydraulic fracturing process under a polyaxial stress state.In the numerical model,injection pressures after breakdown(postbreakdown)are varied to study the impact on fracture growth.The fluid pressure front and crack front are identified in the numerical model to analyze the dynamic relationship between fluid diffusion and fracture propagation.Following the hydraulic fracturing test,the polyaxial stresses are rotated to investigate the influence of the stress field rotation on the fracture slip behavior and permeability.The results show that fracture propagation guides fluid diffusion under a high postbreakdown injection pressure.The crack front runs ahead of the fluid pressure front.Under a low postbreakdown injection pressure,the fluid pressure front gradually reaches the crack front,and fluid diffusion is the main driving factor of fracture propagation.Under polyaxial stress conditions,fluid injection not only opens tensile fractures but also induces hydroshearing.When the polyaxial stress is rotated,the fracture slip direction of a fully extended fracture is consistent with the shear stress direction.The fracture slip direction of a partly extended fracture is influenced by the increase in shear stress.Normal stress affects the permeability evolution by changing the average mechanical aperture.Shear stress can induce shearing and sliding on the fracture plane,thereby increasing permeability.展开更多
This study presents a coupled thermo-hydro-mechanical-fatigue(THM-F)model,developed based on variational phase-field fatigue theory,to simulate the freeze-thaw(F-T)damage process in concrete.The fracture phasefield mo...This study presents a coupled thermo-hydro-mechanical-fatigue(THM-F)model,developed based on variational phase-field fatigue theory,to simulate the freeze-thaw(F-T)damage process in concrete.The fracture phasefield model incorporates the F-T fatigue mechanism driven by energy dissipation during the free energy growth stage.Using microscopic inclusion theory,we derive an evolution model of pore size distribution(PSD)for concrete under F-T cycles by treating pore water as columnar inclusions.Drawing upon pore ice crystal theory,calculation models that account for concrete PSD characteristics are established to determine ice saturation,permeability coefficient,and pore pressure.To enhance computational accuracy,a segmented Gaussian integration strategy based on aperture levels is employed.The pore pressure estimation model is applied to assess the frost resistance of concrete with varying air-entraining agent contents,confirming that optimal air-entrainment significantly improves pore structure and lowers the overall freezing point of pore ice.The derived permeability coefficient and pore pressure estimation models are integrated into the THM-F coupled framework,which employs a staggered iterative solution scheme for efficient simulation.Mesoscale numerical examples of concrete demonstrate that the proposed THM-F model effectively captures structural degradation and accurately tracks the procession of F-T-induced fatigue cracks.Validations against experimental measurements,including temperature variations,stress-strain curves,and strain history,shows excellent agreement,underscoring the model’s accuracy and applicability.This study provides a robust theoretical and computational framework for quantitative analysis of coupled F-T-fatigue damage in concrete.展开更多
The Kuroshio Extension(KE)is one of the most eddy-energetic regions in the global ocean.However,most mesoscale eddy studies in the region are focused on surface eddies and the structure and characteristics of three-di...The Kuroshio Extension(KE)is one of the most eddy-energetic regions in the global ocean.However,most mesoscale eddy studies in the region are focused on surface eddies and the structure and characteristics of three-dimensional(3-D)eddies require additional research.In this study,we proposed a 3-D eddy identification and tracking algorithm based on pressure anomalies,similar to sea level anomalies(SLAs)for surface eddy identification.We applied this scheme to a 5-year(2008-2012)high-resolution numerical product to develop a 3-D eddy dataset in the KE.The reliability of the numerical product was verified by the 5-year temperature/salinity hydrological characteristics and surface eddy distribution.According to the 3-D eddy tracking dataset,the number of eddies decreased dramatically as the eddy existence-time increased and more anticyclonic eddies(AEs)had an existence-time longer than 1 week than cyclonic eddies(CEs).We presented daily variations in the 3-D structure of two 3-D eddy-tracking trajectories that exhibit a certain jump in depth and a shift toward the west and equator.In addition to the bowl,lens,and cone eddies that have been discovered by previous researchers,we found that there is a cylindrical eddy,and its eddy radii are almost consistent across all layers.CEs cause significant negative temperature anomalies,“negative-positive”salinity anomalies,and sinking current fields in the KE region,while AEs cause positive temperature anomalies,“positive-negative”salinity anomalies,and upward current fields.The four types of eddies have different effects on the temperature/salinity anomalies and current field distribution which are related to their structure.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
This paper presents a numerical study of the flow topologies of three-dimensional （3D） flows in a high pressure compressor stator blade row without and with boundary layer aspiration on the hub wall. The stator blad...This paper presents a numerical study of the flow topologies of three-dimensional （3D） flows in a high pressure compressor stator blade row without and with boundary layer aspiration on the hub wall. The stator blade is representative of the first stage operating under transonic inlet conditions and the blade design encourages development of highly complex 3D flows. The blade has a small tip clearance. The computational fluid dynamics （CFD） studies show progressive increase of hub corner stall with the increase in incidence. Aspiration is implemented on the hub wall via a slot in the comer between the hub wall and the suction surface. The CFD studies show aspiration to be sensitive to the suction flow rate; lower rate leads to very complex flow struc- tures and increased level of losses whereas higher rate renders aspiration effective for control of hub comer separation. The flow topologies are studied by trace of skin friction lines on the walls. The nature of flow can be explained by the topological rules of closed separation. Furthermore, a deeper analysis is done for a particular case with advanced criterion to test the non-degeneracy of critical points in the flow field.展开更多
文摘Yingqiong basin is a proven hydrocarbon-rich basin in South China Sea. There are a number of large exploration prospects in high temperature and over-pressured formations, especially in Yacheng Block of Qiongdongnan basin and Dongfang District of Yinggehai Basin. Owing to good exploration situation, we have already achieved proven geological reserves over 1000 × 108 m3. In recent years, a few drilled HPHT wells have confirmed that pressure predicted by conventional method was wildly inaccurate. From the view of regional stress, the accuracy of the pressure prediction will be substantially improved. Accurate pressure prediction and three-dimensional pressure modeling which are based on three-dimensional lithology modeling are the cornerstone to achieve exploration breakthrough. In this paper, the use of the triple constraint trend lithology model broke through the traditional method of seismic lithology prediction only by means of impedance threshold value. Compared with actual data and prediction, it confirms that three-dimensional pressure modeling method is reasonable and effective, and has a wide prospect of application.
基金supported by the National Natural Science Foundation of China(No.12301672)the Shanghai Science and Technology Innovation Action Plan(Yangfan Special Project),China(No.23YF1401300)。
文摘The micro-riblet structures have been demonstrated effective in controlling the Total Pressure Loss(TPL)of aero-engine blades.However,due to the considerable scale gap between micro-texture and an actual aero-engine blade,wind tunnel tests and numerical simulations with massive grids directly describing the global flow field are costly for aerodynamic evaluation.Furthermore,the fine micro surface structure brings unavoidable manufacturing errors,and the probability prediction contributes to gaining the confidence interval of the results.Therefore,a novel relay-based probabilistic model for multi-fidelity scenarios in the TPL prediction of a compressor cascade with micro-riblet surfaces is proposed to trade off accuracy and efficiency.Combined with the low-fidelity flow data generated by an aerodynamic solution strategy using the boundary surrogate model and the high-fidelity flow data from the experiment,the relay-based modeling has been achieved through knowledge transferring,and the confidence interval can be provided by the Gaussian Process Regression(GPR)model.The TPL of compressor cascades with micro-riblet surfaces under different surface structures at March number Ma=0.64,0.74,0.84 have been evaluated using the Relay-Based Probabilistic(RBP)model.The results illustrate that the RBP model could provide higher accuracy than the Single-Fidelity-Data-Driven(SFDD)prediction model,which show the promising potential of multi-fidelity scenarios data fusion in the aerodynamic evaluation of multi-scale configurations.
基金supported by the National Key Research and Development Program(2021YFB150740401)National Natural Science Foundation of China(42202336)the CAS Pioneer Hundred Talents Program in China(Y826031C01)。
文摘Hydraulic stimulation technology is widely employed to enhance the permeability of geothermal reservoirs.Nevertheless,accurately predicting hydraulic fracture propagation in complex geological conditions remains challenging,thereby hindering the effective utilization of existing natural fractures.In this study,a phase field model was developed utilizing the finite element method to examine the influence of fluid presence,stress conditions,and natural fractures on the initiation and propagation of hydraulic fractures.The model employs Biot's poroelasticity theory to establish the coupling between the displacement field and the fluid field,while the phase field theory is applied to simulate fracture behavior.The results show that whenσ_(x0)/σ_(y0)<3 or qf<20 kg/(m^(3)·s),the presence of natural fractures can alter the original propagation direction of hydraulic fractures.Conversely,in the absence of these conditions,the propagation path of natural fractures is predominantly influenced by the initial stress field.Furthermore,based on the analysis of breakdown pressure and damage area,the optimal intersection angle between natural fractures and hydraulic fractures is determined to range from 45°to 60°.Finally,once a dominant channel forms,initiating and propagating hydraulic fractures in other directions becomes increasingly difficult,even in highly fractured areas.This method tackles the challenges of initiating and propagating hydraulic fractures in complex geological conditions,providing a theoretical basis for optimizing Enhanced Geothermal System(EGS)projects.
文摘A three dimensional finite element program incorporating actually measured vertical tire-pavement contact pressure(TPCP) was utilized for modeling the mechanistic responses in asphalt concrete(AC) layers by simulating various vehicle motions:stationary and non-stationary(i.e.in acceleration or deceleration mode).Analysis of the results indicated the following items.1) It is critical to use the vertical TPCP as the design control criteria for the tensile strains at the bottom of the AC layer when the base layer modulus is lower in magnitude(e.g.≤400 MPa);however,when the base layer modulus is higher in magnitude(e.g.≥7 000 MPa),the horizontal TPCP and the tensile strains in the X-direction at the surface of the AC layer should also be considered as part of the design response criteria.2) The definition of "overload" needs to be revised to include tire pressure over-inflation,i.e.,a vehicle should be considered to be overloaded if the wheel load exceeds the specification and/or the tire inflation pressure is higher than the specification.3) Light trucks have more structural impact on the strain responses and pavement design when the thickness of the surfacing AC layer is thinner(e.g.≤50 mm).4) The acceleration of a vehicle does not significantly impact the AC surface distresses such as rutting at the top of the upgrade slopes or intersections;however,vehicle deceleration can dramatically induce horizontal shear strains and consequently,aggravate shoving and rutting problems at the highway intersections.Evidently,these factors should be taken into account during mechanistic stress-strain modeling and structural design of asphalt pavements.
基金funding support from the National Natural Science Foundation of China(Grant Nos.41972271 and 42177127)Sanya Science and Education Innovation Park of Wuhan University of Technology(Grant No.2020KF0007)。
文摘A novel fiber Bragg grating(FBG)sensor with three-dimensional(3D)fused deposition modeling(FDM)approach is proposed for effective stress measurement in soil mass.The three-diaphragm structure design is developed to measure earth and water pressures simultaneously.The proposed transducer has advantages of small size,high sensitivity,low cost,immunity to electromagnetic interference and rapid prototyping.The working principle,design parameters,and manufacturing details are discussed.The proposed transducer was calibrated for earth and water pressures measurement by using weights and a specially designed pressure chamber,respectively.The calibration results showed that the wavelength of the transducer was proportional to the applied pressure.The sensitivity coefficients of the earth and water pressures were 12.633 nm/MPa and 6.282 nm/MPa,respectively.Repeated tests and error analysis demonstrated the excellent stability and accuracy of the earth and water pressure measurements.The performance of the proposed transducer was further verified by a model experimental test and numerical analysis,which indicated that the proposed transducer has great potential for practical applications.
基金Project(2024YFC2911000)supported by the National Key Research and Development Program Young Scientist Project,ChinaProject(2022HWYQ-078)supported by the Natural Science Foundation of Shandong Province of China+1 种基金Project(tsqn202103074)supported by the"Taishan Scholars Young Expert Program"of Shandong Province,ChinaProject(2023GX051)supported by the Tai'an Science and Technology Innovation Development Project(Policy Guidance),China。
文摘High ground temperature and unloading disturbance have emerged as critical factors impacting the property of cemented gauge-fly ash backfill(CGFB).The characteristics of energy and damage in CGFB were analyzed under conditions of high ground temperature and unloading by conducting triaxial unloading tests with different initial confining pressures on CGFB that had been cured at various temperatures.Based on dissipative energy,triaxial unloading confining pressure damage constitutive model of CGFB was constructed.It has been demonstrated that the ratio of elastic strain energy in CGFB decreases and the ratio of dissipated energy increases at the end of unloading increases under higher curing temperature.The change in the elastic energy consumption ratio curve of CGFB,which shifts from a gradual increase to a swift rise at a certain"inflection point",can be utilized as a criterion for evaluating the failure of the unloading strength of CGFB.The triaxial unloading damage constitutive model for CGFB divides the damage progression into three distinct phases:initial damage stage,accelerated damage development stage,and rapid damage growth stage.The research findings offer a theoretical foundation for evaluating the extent of damage to CGFB caused by the combined influences of elevated ground temperature and unloading.
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supported by the National Natural Science Foundation of China(Grant Nos.U24A2088 and 42277174)the Fundamental Research Funds for the Central Universities,China(Grant No.2024JCCXSB01).
文摘During fully mechanized caving mining of thick coal seams,a large amount of strain energy accumulates in the roof,especially when the roof is thick and hard,making it difficultfor the roof to collapse naturally.When the roof eventually collapses,the accumulated energy is released instantaneously,exerting a strong impact on the roadway.To address this issue,we proposed the synergistic control method of directional comprehensive pressure relief and energy-absorbing support(PREA)for roadways with hard roofs.In this study,we developed a three-dimensional physical model test apparatus for roof cutting and pressure relief.The 122108 ventilation roadway at the Caojiatan Coal Mine,which has a thick and hard roof,was taken as the engineering example.We analyzed the evolution patterns of stress and displacement in both the stope and the roadway surrounding rocks under different schemes.The PREA reinforcement mechanism for the roadway was investigated through comparative model tests between the new and original methods.The results showed that,compared to the original method,the new method reduced surrounding rock stress by up to 60.4%,and the roadway convergence decreased by up to 52.1%.Based on these results,we proposed corresponding engineering recommendations,which can guide fieldreinforcement design and application.The results demonstrate that the PREA method effectively reduces stress and ensures the safety and stability of the roadway.
基金Project(52372402)supported by the National Natural Science Foundation of China。
文摘The pressure comfort of passengers and crew in high-speed trains faces significant challenges under alternating open-tunnel conditions.To better understand the mechanism of pressure transmission and control interior pressure fluctuations in high-altitude regions,this study develops an interior pressure fluctuation model.By establishing the frameworks of the non-ideal gas state equation and the polytropic process equation,gas heat transfer and mass transfer were expressed through the first law of thermodynamics and the continuity equation.Simulation results,evaluated by root mean square error,coefficient of determination,peak-to-peak error,and pressure change rate,show that the proposed model closely aligns with measured signals in both overall trends and local details.Data from various train types and tunnel scenarios further demonstrate the model's accuracy and practical applicability.This study provides a critical foundation for evaluating interior pressure comfort for high-speed trains in high-altitude regions.
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.
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.
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.
基金supported by the National Natural Science Foundation of China (No.52274073)National Key R&D Program of China (No.2024YFB4007100)+2 种基金Chongqing Natural Science Foundation Innovation and Development Joint Fund (Municipal Education Commission)(No.CSTB2024NSCQ-LZX0056)Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety (No.SKLGGES-024006)financial support from the Rut and Sten Brand Foundation
文摘Salt caverns are widely used for energy storage.During gas storage,the internal gas pressure fluctuates cyclically in response to energy demand,making it essential to assess how these pressure variations affect rock deformation.In this study,experiments were conducted under different cyclic gas pressure conditions to investigate this effect.The findings indicate that(1)the deformation process of salt rock can be segmented into three stages:the deceleration stage,the steady-state stage,and the acceleration stage.(2)When the axial pressure remains constant,both axial and radial deformations exhibit a stepwise increasing trend in response to cyclic gas pressure variations.Similarly,under axial graded loading,the deformations also demonstrate a progressive rise.By analyzing the deformation differences and model coefficient fluctuations within a single gas pressure cycle,it is found that radial deformation is higher sensitive to changes in cyclic gas pressure.(3)The axial deformation shows a stepwise increase,and the radial deformation showed a cyclic change with changing gas pressure.Therefore,the cyclic gas pressure influence factor α,axial loading influence factor β,and state variable σ^(*)are introduced to develop a viscoplastic ontological model that accounts for the impacts of cyclic gas pressure,confining pressure and axial stress.Validated by the deformation data,the new model can better fit both the axial deformation and the radial deformation of the three stages and has strong applicability and accuracy by changing only fewer parameters.The state variable rate shows the same stage as the deformation rate and residual strain of salt rock,which can better reflect the internal hardening of salt rock.
基金the National Natural Science Foundation of China(No.52474068)the Major Collab-orative Innovation Project of Prospecting Breakthrough Stra-tegic Action in Guizhou Province(No.[2022]ZD001-003).
文摘Coalbed methane(CBM)is a vital unconventional energy resource,and predicting its spatiotemporal pressure dynamics is crucial for efficient development strategies.This paper proposes a novel deep learningebased data-driven surrogate model,AxialViT-ConvLSTM,which integrates AxialAttention Vision Transformer,ConvLSTM,and an enhanced loss function to predict pressure dynamics in CBM reservoirs.The results showed that the model achieves a mean square error of 0.003,a learned perceptual image patch similarity of 0.037,a structural similarity of 0.979,and an R^(2) of 0.982 between predictions and actual pressures,indicating excellent performance.The model also demonstrates strong robustness and accuracy in capturing spatialetemporal pressure features.
基金funded by the Research on Intelligent Mining Geological Model and Ventilation Model for Extremely Thin Coal Seam in Heilongjiang Province,China(2021ZXJ02A03)the Demonstration of Intelligent Mining for Comprehensive Mining Face in Extremely Thin Coal Seam in Heilongjiang Province,China(2021ZXJ02A04)the Natural Science Foundation of Heilongjiang Province,China(LH2024E112).
文摘Coal dust explosions are severe safety accidents in coal mine production,posing significant threats to life and property.Predicting the maximum explosion pressure(Pm)of coal dust using deep learning models can effectively assess potential risks and provide a scientific basis for preventing coal dust explosions.In this study,a 20-L explosion sphere apparatus was used to test the maximum explosion pressure of coal dust under seven different particle sizes and ten mass concentrations(Cdust),resulting in a dataset of 70 experimental groups.Through Spearman correlation analysis and random forest feature selection methods,particle size(D_(10),D_(20),D_(50))and mass concentration(Cdust)were identified as critical feature parameters from the ten initial parameters of the coal dust samples.Based on this,a hybrid Long Short-Term Memory(LSTM)network model incorporating a Multi-Head Attention Mechanism and the Sparrow Search Algorithm(SSA)was proposed to predict the maximum explosion pressure of coal dust.The results demonstrate that the SSA-LSTM-Multi-Head Attention model excels in predicting the maximum explosion pressure of coal dust.The four evaluation metrics indicate that the model achieved a coefficient of determination(R^(2)),root mean square error(RMSE),mean absolute percentage error(MAPE),and mean absolute error(MAE)of 0.9841,0.0030,0.0074,and 0.0049,respectively,in the training set.In the testing set,these values were 0.9743,0.0087,0.0108,and 0.0069,respectively.Compared to artificial neural networks(ANN),random forest(RF),support vector machines(SVM),particle swarm optimized-SVM(PSO-SVM)neural networks,and the traditional single-model LSTM,the SSA-LSTM-Multi-Head Attention model demonstrated superior generalization capability and prediction accuracy.The findings of this study not only advance the application of deep learning in coal dust explosion prediction but also provide robust technical support for the prevention and risk assessment of coal dust explosions.
基金supported by the Knowledge Innovation Program of Wuhan-Basic Research (Grant No.2022010801010159)support from the Helmholtz Association's Initiative and Networking Fund for the Helmholtz Young Investigator Group ARES (Contract number VH-NG-1516)supported by the Swedish Radiation Safety Authority (Project SSM2020-2758).
文摘Understanding the hydromechanical behavior and permeability stress sensitivity of hydraulic fractures is fundamental for geotechnical applications associated with fluid injection.This paper presents a three-dimensional(3D)benchmark model of a laboratory experiment on graywacke to examine the dynamic hydraulic fracturing process under a polyaxial stress state.In the numerical model,injection pressures after breakdown(postbreakdown)are varied to study the impact on fracture growth.The fluid pressure front and crack front are identified in the numerical model to analyze the dynamic relationship between fluid diffusion and fracture propagation.Following the hydraulic fracturing test,the polyaxial stresses are rotated to investigate the influence of the stress field rotation on the fracture slip behavior and permeability.The results show that fracture propagation guides fluid diffusion under a high postbreakdown injection pressure.The crack front runs ahead of the fluid pressure front.Under a low postbreakdown injection pressure,the fluid pressure front gradually reaches the crack front,and fluid diffusion is the main driving factor of fracture propagation.Under polyaxial stress conditions,fluid injection not only opens tensile fractures but also induces hydroshearing.When the polyaxial stress is rotated,the fracture slip direction of a fully extended fracture is consistent with the shear stress direction.The fracture slip direction of a partly extended fracture is influenced by the increase in shear stress.Normal stress affects the permeability evolution by changing the average mechanical aperture.Shear stress can induce shearing and sliding on the fracture plane,thereby increasing permeability.
基金supported by the National Natural Science Foundation of China(Grant Nos.11932006 and 12172121).
文摘This study presents a coupled thermo-hydro-mechanical-fatigue(THM-F)model,developed based on variational phase-field fatigue theory,to simulate the freeze-thaw(F-T)damage process in concrete.The fracture phasefield model incorporates the F-T fatigue mechanism driven by energy dissipation during the free energy growth stage.Using microscopic inclusion theory,we derive an evolution model of pore size distribution(PSD)for concrete under F-T cycles by treating pore water as columnar inclusions.Drawing upon pore ice crystal theory,calculation models that account for concrete PSD characteristics are established to determine ice saturation,permeability coefficient,and pore pressure.To enhance computational accuracy,a segmented Gaussian integration strategy based on aperture levels is employed.The pore pressure estimation model is applied to assess the frost resistance of concrete with varying air-entraining agent contents,confirming that optimal air-entrainment significantly improves pore structure and lowers the overall freezing point of pore ice.The derived permeability coefficient and pore pressure estimation models are integrated into the THM-F coupled framework,which employs a staggered iterative solution scheme for efficient simulation.Mesoscale numerical examples of concrete demonstrate that the proposed THM-F model effectively captures structural degradation and accurately tracks the procession of F-T-induced fatigue cracks.Validations against experimental measurements,including temperature variations,stress-strain curves,and strain history,shows excellent agreement,underscoring the model’s accuracy and applicability.This study provides a robust theoretical and computational framework for quantitative analysis of coupled F-T-fatigue damage in concrete.
文摘The Kuroshio Extension(KE)is one of the most eddy-energetic regions in the global ocean.However,most mesoscale eddy studies in the region are focused on surface eddies and the structure and characteristics of three-dimensional(3-D)eddies require additional research.In this study,we proposed a 3-D eddy identification and tracking algorithm based on pressure anomalies,similar to sea level anomalies(SLAs)for surface eddy identification.We applied this scheme to a 5-year(2008-2012)high-resolution numerical product to develop a 3-D eddy dataset in the KE.The reliability of the numerical product was verified by the 5-year temperature/salinity hydrological characteristics and surface eddy distribution.According to the 3-D eddy tracking dataset,the number of eddies decreased dramatically as the eddy existence-time increased and more anticyclonic eddies(AEs)had an existence-time longer than 1 week than cyclonic eddies(CEs).We presented daily variations in the 3-D structure of two 3-D eddy-tracking trajectories that exhibit a certain jump in depth and a shift toward the west and equator.In addition to the bowl,lens,and cone eddies that have been discovered by previous researchers,we found that there is a cylindrical eddy,and its eddy radii are almost consistent across all layers.CEs cause significant negative temperature anomalies,“negative-positive”salinity anomalies,and sinking current fields in the KE region,while AEs cause positive temperature anomalies,“positive-negative”salinity anomalies,and upward current fields.The four types of eddies have different effects on the temperature/salinity anomalies and current field distribution which are related to their structure.
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.
文摘This paper presents a numerical study of the flow topologies of three-dimensional （3D） flows in a high pressure compressor stator blade row without and with boundary layer aspiration on the hub wall. The stator blade is representative of the first stage operating under transonic inlet conditions and the blade design encourages development of highly complex 3D flows. The blade has a small tip clearance. The computational fluid dynamics （CFD） studies show progressive increase of hub corner stall with the increase in incidence. Aspiration is implemented on the hub wall via a slot in the comer between the hub wall and the suction surface. The CFD studies show aspiration to be sensitive to the suction flow rate; lower rate leads to very complex flow struc- tures and increased level of losses whereas higher rate renders aspiration effective for control of hub comer separation. The flow topologies are studied by trace of skin friction lines on the walls. The nature of flow can be explained by the topological rules of closed separation. Furthermore, a deeper analysis is done for a particular case with advanced criterion to test the non-degeneracy of critical points in the flow field.
