Prediction of three-dimensional ocean temperature in the South China Sea based on time series gridded data and a dynamic spatiotemporal graph neural network

Ocean temperature is an important physical variable in marine ecosystems,and ocean temperature prediction is an important research objective in ocean-related fields.Currently,one of the commonly used methods for ocean temperature prediction is based on data-driven,but research on this method is mostly limited to the sea surface,with few studies on the prediction of internal ocean temperature.Existing graph neural network-based methods usually use predefined graphs or learned static graphs,which cannot capture the dynamic associations among data.In this study,we propose a novel dynamic spatiotemporal graph neural network(DSTGN)to predict threedimensional ocean temperature(3D-OT),which combines static graph learning and dynamic graph learning to automatically mine two unknown dependencies between sequences based on the original 3D-OT data without prior knowledge.Temporal and spatial dependencies in the time series were then captured using temporal and graph convolutions.We also integrated dynamic graph learning,static graph learning,graph convolution,and temporal convolution into an end-to-end framework for 3D-OT prediction using time-series grid data.In this study,we conducted prediction experiments using high-resolution 3D-OT from the Copernicus global ocean physical reanalysis,with data covering the vertical variation of temperature from the sea surface to 1000 m below the sea surface.We compared five mainstream models that are commonly used for ocean temperature prediction,and the results showed that the method achieved the best prediction results at all prediction scales.

Dynamic Modeling and Sensitivity Analysis for an MEA-Based CO_(2) Capture Absorber

The absorber is the key unit in the post-combustion monoethanolamine(MEA)-based carbon dioxide(CO_(2))capture process.A rate-based dynamic model for the absorber is developed and validated using steady-state experimental data reported in open literature.Sensitivity analysis is performed with respect to important model parameters associated with the reaction,mass transport and phy-sical property relationships.Then,a singular value decomposition(SVD)-based subspace parameter estimation method is proposed to improve the model accu-racy.Finally,dynamic simulations are carried out to investigate the effects of the feed rate of lean MEA solution and the flue inlet conditions.Simulation results indicate that the established dynamic model can reasonably reflect the physical behavior of the absorber.Some new insights are gained from the simulation results.

Research on Quantitative Identification of Three-Dimensional Connectivity of Fractured-Vuggy Reservoirs

The fractured-vuggy carbonate oil resources in the western basin of China are extremely rich.The connectivity of carbonate reservoirs is complex,and there is still a lack of clear understanding of the development and topological structure of the pore space in fractured-vuggy reservoirs.Thus,effective prediction of fractured-vuggy reservoirs is difficult.In view of this,this work employs adaptive point cloud technology to reproduce the shape and capture the characteristics of a fractured-vuggy reservoir.To identify the complex connectivity among pores,fractures,and vugs,a simplified one-dimensional connectivity model is established by using the meshless connection element method(CEM).Considering that different types of connection units have different flow characteristics,a sequential coupling calculation method that can efficiently calculate reservoir pressure and saturation is developed.By automatic history matching,the dynamic production data is fitted in real-time,and the characteristic parameters of the connection unit are inverted.Simulation results show that the three-dimensional connectivity model of the fractured-vuggy reservoir built in this work is as close as 90%of the fine grid model,while the dynamic simulation efficiency is much higher with good accuracy.

Three-dimensional dynamics of supported pipes conveying fluid

This paper deals with the three-dimensional dynamics and postbuckling behavior of flexible supported pipes conveying fluid, considering flow velocities lower and higher than the critical value at which the buckling instability occurs. In the case of low flow velocity, the pipe is stable with a straight equilibrium position and the dynamics of the system can be examined using linear theory. When the flow velocity is beyond the critical value, any motions of the pipe could be around the postbuckling configuration(non-zero equilibrium position) rather than the straight equilibrium position, so nonlinear theory is required. The nonlinear equations of perturbed motions around the postbuckling configuration are derived and solved with the aid of Galerkin discretization. It is found, for a given flow velocity,that the first-mode frequency for in-plane motions is quite different from that for out-of-plane motions. However, the second-or third-mode frequencies for in-plane motions are approximately equal to their counterparts for out-of-plane motions, keeping almost constant values with increasing flow velocity. Moreover, the orientation angle of the postbuckling configuration plane for a buckled pipe can be significantly affected by initial conditions, displaying new features which have not been observed in the same pipe system factitiously supposed to deform in a single plane.

Three-dimensional Computational Fluid Dynamics Modeling of Two-phase Flow in a Structured Packing Column

Characterizing the complex two-phase hydrodynamics in structured packed columns requires a power- ful modeling tool. The traditional two-dimensional model exhibits limitations when one attempts to model the de- tailed two-phase flow inside the columns. The present paper presents a three-dimensional computational fluid dy- namics （CFD） model to simulate the two-phase flow in a representative unit of the column. The unit consists of an CFD calculations on column packed with Flexipak 1Y were implemented within the volume of fluid （VOF） mathe- matical framework. The CFD model was validated by comparing the calculated thickness of liquid film with the available experimental data. Special attention was given to quantitative analysis of the effects of gravity on the hy- drodynamics. Fluctuations in the liquid mass flow rate and the calculated pressure drop loss were found to be quali- tatively in agreement with the experimental observations.

Predicting the Dynamic Behavior of Asphalt Concrete Using Three-dimensional Discrete Element Method

A user-defined three-dimensional （3D） discrete element model was presented to predict the dynamic modulus and phase angle of asphalt concrete （AC）. The 3D discrete element method （DEM） model of AC was constructed employing a user-defined computer program developed using the ＂Fish＂ language in PFC3D. Important microstructural features of AC were modeled, including aggregate gradation, air voids and mastic. The irregular shape of aggregate particle was modeled using a clump of spheres. The developed model was validated through comparing with experimental measurements and then used to simulate the cyclic uniaxial compression test, based on which the dynamic modulus and phase angle were calculated from the output stress- strain relationship. The effects of air void content, aggregate stiffness and volumetric fraction on AC modulus were further investigated. The experimental results show that the 3D DEM model is able to accurately predict both dynamic modulus and phase angle of AC across a range of temperature and loading frequencies. The user- defined 3D model also demonstrated significant improvement over the general existing two-dimensional models.

Science Letters:Dynamic concision for three-dimensional reconstruction of human organ built with virtual reality modelling language (VRML)

This research studies the process of 3D reconstruction and dynamic concision based on 2D medical digital images using virtual reality modelling language (VRML) and JavaScript language, with a focus on how to realize the dynamic concision of 3D medical model with script node and sensor node in VRML. The 3D reconstruction and concision of body internal organs can be built with such high quality that they are better than those obtained from the traditional methods. With the function of dynamic concision, the VRML browser can offer better windows for man-computer interaction in real-time environment than ever before. 3D reconstruction and dynamic concision with VRML can be used to meet the requirement for the medical observation of 3D reconstruction and have a promising prospect in the fields of medical imaging.

Three-dimensional coordinates test method with uncertain projectile proximity explosion position based on dynamic seven photoelectric detection screen

To objectively obtain the three-dimensional coordinates of the projectile fuze proximity explosion when projectile intersects the head of missile target, we propose a dynamic seven photoelectric detection screen test method, which is made up of six plane detection screens and a flash photoelectric dynamic detection screen. The three-dimensional coordinates calculation model of the projectile proximity explosion position based on seven plane detection screens with dynamic characteristics is established.According to the relation of the dynamic seven photoelectric detection screen planes and the time values,the analytical function of the projectile proximity explosion position parameters under non-linear motion is derived. The projectile signal filtering method based on discrete wavelet transform is explored in this work. Additionally, the projectile signal recognition algorithm using an improved particle swarm is proposed. Based on the characteristics of the time duration and the signal peak error for the projectile passing through the detection screen, the signals attribution of the same projectile passing through six detection screens are analyzed for obtaining precise time values of the same projectile passing through the detection screens. On the basis of the projectile fuze proximity explosion test, the linear motion model and the proposed non-linear motion model are used to calculate and compare the same group of projectiles proximity explosion position parameters. The comparison of test results verifies that the proposed test method and calculation model in this work accurately obtain the actual projectile proximity explosion position parameters.

Numerical simulations and comparative analysis of two- and three-dimensional circulating fluidized bed reactors for CO2 capture

Carbon dioxide(CO2),the main gas emitted from fossil burning,is the primary contributor to global warming.Circulating fluidized bed reactor(CFBR)is proved as an energy-efficient method for post-combustion CO2 capture.The numerical simulation by computational fluid dynamics(CFD)is believed as a promising tool to study CO2 adsorption process in CFBR.Although three-dimensional(3D)simulations were proved to have better predicting performance with the experimental results,two-dimensional(2D)simulations have been widely reported for qualitative and quantitative studies on gas-solid behavior in CFBR for its higher computational efficiency recently.However,the discrepancies between 2D and 3D simulations have rarely been evaluated by detailed study.Considering that the differences between the 2D and 3D simulations will vary substantially with the changes of independent operating conditions,it is beneficial to lower computational costs to clarify the effects of dimensionality on the numerical CO2 adsorption runs under various operating conditions.In this work,the comparative analysis for CO2 adsorption in 2D and 3D simulations was conducted to enlighten the effects of dimensionality on the hydrodynamics and reaction behaviors,in which the separation rate,species distribution and hydrodynamic characteristics were comparatively studied for both model frames.With both accuracy and computational costs considered,the viable suggestions were provided in selecting appropriate model frame for the studies on optimization of operating conditions,which directly affect the capture and energy efficiencies of cyclic CO2 capture process in CFBR.

CONVOLUTION OF THE IMPACT THREE-DIMENSIONAL ELASTO-DYNAMICS AND DYNAMIC STRESS INTENSITY FACTOR FOR AN ELLIPTIC CRACK

This paper presents a formulation for three-dimensional elasto-dynamics with an elliptic crack based on the Laplace and Fourier transforms and the convolution theorem. The dynamic stress intensity factor for the crack is determined by solving a Fredholm integral equation of the first kind. The results of this paper are very close to those given by the two-dimensional dual integral equation method.

THE CAPTURE RANGES AND THE DANGEROUS RANGES FOR THE THREE-DIMENSIONAL TWO-AIRCRAFT COMBAT PROBLEM

In this paper, we use differential game theory to study the three-dimensional two-aircraft air-to-air combat problem. We give the ways to determine the Capture Ranges (CR) and the Dangerous Ranges (DR) for these two aircraft according to the target entry directions, barrier and isochronic lines respectively. The simulations are given by referring to two sets of real aircraft parameters. After discussing the simulation results, we have obtained some conclusions that match the real air-to-air combat situation quite well.

Three-Dimensional Nonlinear Dynamic Model and Macro Control of Real Estate

In this paper, according to economics of real estate and macro-control theory, combine with the characteristics of the real estate market, macro-control of the real estate market is studied. After giving the dynamic model of three-dimensional nonlinear differential equations based on the total number of houses on the real estate business, the government’s averages housing investment funds and the standard price, systematically established the stability conditions of equilibrium point for this model. What’s more, through the use of extreme value analysis model, government funds have been invested in real estate business building devotion principles and the construction base of the real estate businessmen has also been estimated successfully. This provides the corresponding theoretical basis for government macro control policy-making.

In-situ three-dimensional visualization of dynamic tension deformation in ferrite stainless steels

An improved three-dimensional （3-D） experimental visualization methodology is presented tor evaluating the fracture mechanisms of ferritic stainless steels by in-situ tensile testing with an environmental scanning electron microscope （ESEM）. The samples were machined with a radial notched shape and a sloped surface. Both planar surface deformation and sloping surface deformation-induced microvoids were observed during dynamic tension experiments, where a greater amount of information could be obtained from the sloping surface. The results showed that microvoids formed at the grain boundaries of highly elongated large grains. The microvoids nucleated in the severely deformed regions grew nearly parallel to the tensile axis, predominantly along the grain boundaries. The microvoids nucleated at the interface of particles and the matrix did not propagate due to the high plasticity of the matrix. The large microvoids propagated and showed a zigzag shape along the grain boundaries,seemingly a consequence of the fracture of the slip bands caused by dislocation pile-ups. The final failure took place due to the reduction of the load-beating area.

Impact dynamics analysis of free-floating space manipulator capturing satellite on orbit and robust adaptive compound control algorithm design for suppressing motion

The impact dynamics, impact effect, and post-impact unstable motion sup- pression of free-floating space manipulator capturing a satellite on orbit are analyzed. Firstly, the dynamics equation of free-floating space manipulator is derived using the sec- ond Lagrangian equation. Combining the momentum conservation principle, the impact dynamics and effect between the space manipulator end-effector and satellite of the cap- ture process are analyzed with the momentum impulse method. Focusing on the unstable motion of space manipulator due to the above impact effect, a robust adaptive compound control algorithm is designed to suppress the above unstable motion. There is no need to control the free-floating base position to save the jet fuel. Finally, the simulation is proposed to show the impact effect and verify the validity of the control algorithm.

Mechanical analysis of the femoral neck dynamic intersection system with different nail angles and clinical applications

BACKGROUND The femoral neck dynamic intersection system(FNS)is mechanically more stable than other internal fixation techniques.Current studies have confirmed that the structural design of FNS has good biomechanical properties in European and American populations.However,whether the suitability of the FNS's 130°main nail angle design for Asian populations has been thoroughly investigated remains unclear.AIM To compare the biomechanical stability differences among different main nail angles of the FNS in the treatment of femoral neck fractures in Asian populations.METHODS Computed tomography data of the femur of healthy adult male volunteers were imported into Mimics software to create a three-dimensional model of the femur.The model was adapted to the curve using Geomagic software and imported into Solidworks software to construct the Pauwels I femoral neck fracture model and design the FNS internal fixation model using different main nail angles.Afterward,the models were assembled with the FNS fracture model and meshed using the preprocessing Hypermesh software.Subsequently,they were imported into Abaqus software to analyze and evaluate the biomechanical effects of different angles of the FNS main nail on the treatment of femoral neck fractures.RESULTS The peak displacement of the proximal femur under different angles of FNS fixation under stress was 7.446 millimeters in the 120°group and 7.416 millimeters in the 125°group;in the 130°,135°,and 140°FNS fixation groups,the peak displacement was 7.324 millimeters,8.138 millimeters,and 8.246 millimeters,respectively.In the 120°and 125°FNS fixation groups,the maximum stresses were concentrated at the main nail and the anti-rotation screw,which intersected the fracture line of the femur neck,resulting in peak stresses of 200.7 MPa and 138.8 MPa,respectively.Peak stresses of 208.8 MPa,219.8 MPa,and 239.3 MPa were observed on the angular locking plate distal to the locking screw in the 130°,135°,and 140°fixation groups.CONCLUSION FNS has significant stress distribution properties,a minimal proximal femoral displacement,and an optimal stability for treating femoral neck fractures in Asian populations when performed with a 130°main nail angle.

Green Synthesized Liquid-like Dynamic Polymer Chains with Decreased Nonspecific Adhesivity for High-Purity Capture of Circulating Tumor Cells

The capture of circulating tumor cells(CTCs)is of great significance in reducing cancer mortality and complications.However,the nonspecific binding of proteins and white blood cells(WBCs)weakens the targeting capabilities of the capture surfaces,which critically hampers the efficiency and purity of the captured CTCs.Herein,we propose a liquid-like interface design strategy that consists of liquid-like polymer chains and anti-EpCAM modification processes for high-purity and high-efficiency capture of CTCs.The dynamic flexible feature of the liquid-like chains endows the modified surfaces with excellent antiadhesion property for proteins and blood cells.The liquid-like surfaces can capture the target CTCs and show high cell viability due to the environmentfriendly surface modification processes.When liquid-like surface designs were introduced in the deterministic lateral displacement(DLD)-patterned microfluidic chip,the nonspecific adhesion rate of WBCs was reduced by more than fivefold compared to that in the DLD chip without liquid-like interface design,while maintaining comparable capture efficiency.Overall,this strategy provides a novel perspective on surface design for achieving high purity and efficient capture of CTCs.

Bus frequency optimization in a large-scale multi-modal transportation system:integrating 3D-MFD and dynamic traffic assignment

A properly designed public transport system is expected to improve traffic efficiency.A high-frequency bus service would decrease the waiting time for passengers,but the interaction between buses and cars might result in more serious congestion.On the other hand,a low-frequency bus service would increase the waiting time for passengers and would not reduce the use of private cars.It is important to strike a balance between high and low frequencies in order to minimize the total delays for all road users.It is critical to formulate the impacts of bus frequency on congestion dynamics and mode choices.However,as far as the authors know,most proposed bus frequency optimization formulations are based on static demand and the Bureau of Public Roads function,and do not properly consider the congestion dynamics and their impacts on mode choices.To fill this gap,this paper proposes a bi-level optimization model.A three-dimensional Macroscopic Fundamental Diagram based modeling approach is developed to capture the bi-modal congestion dynamics.A variational inequality model for the user equilibrium in mode choices is presented and solved using a double projection algorithm.A surrogate model-based algorithm is used to solve the bi-level programming problem.

Experimental and measured research on three-dimensional deformation law of gas drainage borehole in coal seam

Using self-researched gas drainage borehole stability dynamic monitoring device, three-dimensional deformation characteristics of borehole under steady vertical load were researched experimentally and systematically. This research indicated that under the action of steady loading, the mechanical deformation path of the simulated gas drainage borehole is gradually complicated, and the decay of the borehole circumferential strain is an important characterization of the prediction and early warning of borehole instability and collapse. The horizontal position of borehole occurs compressive strain, and the vertical of which occurs tensile strain under the action of vertical stress. At the initial stage of loading, the vertical strain is more sensitive than that in the horizontal direction. After a certain period of time, the horizontal strain is gradually higher than the vertical one, and the intersection of the borehole horizontal diameter and the hole wall is the stress concentration point. With the increase of the depth of hole, the strain shows a gradual decay trend as a whole, and the vertical strain decays more observably, but there is no absolute position correlation between the amount of strain decay and the increase in borehole depth,and the area within 1.5 times the orifice size is the borehole stress concentration zone.

Design of a Non-cooperative Target Capture Mechanism

A passive compliant non-cooperative target capture mechanism is designed to maintain the non-cooperative target on-orbit. When the relative position between capture mechanism and satellite is confirmed,a pair of four-bar linkages lock the docking ring,which is used for connecting the satellite and the rocket. The mathematical model of capture mechanism and capture space is built by the Denavit-Hartenberg(D-H)method,and the torque of each joint is analyzed by the Lagrange dynamic equation. Besides,the capture condition and the torque of every joint under different capture conditions are analyzed by simulation in MSC. Adams. The results indicate that the mechanism can capture the non-cooperative target satellite in a wide range. During the process of capture,the passive compliant mechanism at the bottom can increase capture space,thereby reducing the difficulty and enhance stability of the capture.

THE APPLICATION OF DISCRETE ELEMENT METHOD IN SOLVING THREE-DIMENTIONAL IMPACT DYNAMICS PROBLEMS

A three-dimensional discrete element model of the connective type is presented. Moreover,a three-dimensional numerical analysis code,which can carry out the transitional pro- cess from connective model(for continuum)to contact model(for non-continuum),is developed for simulating the mechanical process from continuum to non-continuum.The wave propagation process in a concrete block(as continuum)made of cement grout under impact loading is numer- ically simulated with this code.By comparing its numerical results with those by LS-DYNA,the calculation accuracy of the model and algorithm is proved.Furthermore,the failure process of the concrete block under quasi-static loading is demonstrated,showing the basic dynamic tran- sitional process from continuum to non-continuum.The results of calculation can be displayed by animation.The damage modes are similar to the experimental results.The two numerical examples above prove that our model and its code are powerful and efficient in simulating the dynamic failure problems accompanying the transition from continuum to non-continuum.It also shows that the discrete element method(DEM)will have broad prospects for development and application.