The deep potential(DP)is an innovative approach based on deep learning that uses ab initio calculation data derived from density functional theory(DFT),to create high-accuracy potential functions for various materials...The deep potential(DP)is an innovative approach based on deep learning that uses ab initio calculation data derived from density functional theory(DFT),to create high-accuracy potential functions for various materials.Platinum(Pt)is a rare metal with significant potential in energy and catalytic applications,However,there are challenges in accurately capturing its physical properties due to high experimental costs and the limitations of traditional empirical methods.This study employs deep learning methods to construct high-precision potential models for single-element systems of Pt and validates their predictive performance in complex environments.The newly developed DP is highly consistent with DFT results in predicting the stable phases,lattice constants,surface energies,and phonons dispersion relations of Pt,demonstrating outstanding quantum-level accuracy.Additionally,the complex phase transitions and domain formations of Pt are extensively and quantitatively analyzed.Molecular dynamic simulations utilizing the DP approach show that Pt’s face-centered cubic(FCC)structure undergoes a phase transition from solid to liquid at its melting point of 1986 K,this is in close agreement with the experimental value of 2041.5 K.Increased temperature enhances the diffusion of Pt atoms,with a self-diffusion coefficient of 1.17×10-11 m2/s at the melting point,comparable to that of other FCC metals.This result can be utilized for the precise analysis of the fundamental properties of the rare metal Pt at the microscopic scale,and it facilitates the development of binary or multi-component deep potential models that include Pt.展开更多
Researching and comprehending the characteristics of destructive seismic motions is essential for the seismic design of critical infrastructure.This study employs historical data from the M 7.5 earthquake that occurre...Researching and comprehending the characteristics of destructive seismic motions is essential for the seismic design of critical infrastructure.This study employs historical data from the M 7.5 earthquake that occurred in 1850 to simulate the impacts of a M 7.5 event on hydropower stations located in proximity to Xichang.Key factors taken into account in the simulation of seismic motion encompass uncertainties,mixed-source models,and the placement of asperities.Through these simulations,we acquired the peak ground acceleration(PGA),acceleration time histories,and acceleration response spectra for the hydropower facilities affected by the earthquake.To perform a comprehensive analysis,we utilized a multi-scenario stochastic finite fault simulation method to estimate parameters including the minimum,average,and maximum values of PGA and pseudo-spectral acceleration(PSA)response spectra.Additionally,we assessed the 50^(th),84^(th),and 95^(th)percentiles values of the peak ground acceleration and pseudo-spectral acceleration response spectra.The simulation results also include peak ground acceleration field maps and peak ground velocity(PGV)field maps and intensity distribution maps pertaining to the earthquake.The findings demonstrate that the intensity maps produced through the stochastic finite fault method closely correspond with the intensity contour maps published of historical seismic records.These findings offer significant insights for the seismic safety evaluation and design of the specified hydropower stations.Moreover,this multi-scenario methodology can be effectively utilized for other critical infrastructure projects to derive dependable seismic motion parameters.展开更多
1.Introduction Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)is a powerful tool for simulating dense gas-solid reacting flows,which is essential in combustion,metallurgy,and waste management.Traditional...1.Introduction Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)is a powerful tool for simulating dense gas-solid reacting flows,which is essential in combustion,metallurgy,and waste management.Traditional methods face challenges in CFD-DEM modeling of dense gas-solid flows due to multi-scale characteristics,limiting resolution and creating simulation bottlenecks.By integrating fluid dynamics and particle behavior,it optimizes industrial processes.This review highlights advancements,applications,and challenges,emphasizing its role in sustainable engineering.展开更多
A new simulation model for the development of gas condensate reservoirs is introduced based on the influence that phase change,non-Darcy flow,and capillary pressure have on the production of gas condensates.The model ...A new simulation model for the development of gas condensate reservoirs is introduced based on the influence that phase change,non-Darcy flow,and capillary pressure have on the production of gas condensates.The model predicts well performance,including bottom-hole pressure,oil/gas production rate,oil/gas recovery,gaseoil ratio,and the change in produced fluid composition.It also calculates dynamic characters,such as the change of pressure field and oil/gas saturation field during the development of gas condensate reservoirs.The model is applicable to different boundary conditions(both constant-pressure and sealed boundary)and different production modes(both constant-pressure and constant-volume production modes).Model validation attempted using numerical simulation results for sealed boundary conditions with constant-pressure production mode has shown a relatively good match,proving its validity.For constant-pressure boundary conditions with constant-volume production mode,four stages are defined according to the dynamic behavior of production performance in the development of gas condensate reservoirs.展开更多
Accurate simulation of the evolution of freak waves by the wave phase focusing method requires accurate linear and nonlinear properties,especially in deep-water conditions.In this paper,we analyze the ability to simul...Accurate simulation of the evolution of freak waves by the wave phase focusing method requires accurate linear and nonlinear properties,especially in deep-water conditions.In this paper,we analyze the ability to simulate deep-water focused waves of a two-layer Boussinesq-type(BT)model,which has been shown to have excellent linear and nonlinear performance.To further improve the numerical accuracy and stability,the internal wavegenerated method is introduced into the two-layer Boussinesq-type model.Firstly,the sensitivity of the numerical results to the grid resolution is analyzed to verify the convergence of the model;secondly,the focused wave propagating in two opposite directions is simulated to prove the symmetry of the numerical results and the feasibility of the internal wave-generated method;thirdly,the limiting focused wave condition is simulated to compare and analyze the wave surface and the horizontal velocity of the profile at the focusing position,which is in good agreement with the measured values.Meanwhile the simulation of focused waves in very deep waters agrees well with the measured values,which further demonstrates the capability of the two-layer BT model in simulating focused waves in deep waters.展开更多
There are many theories and tools for human or robot motion simulation,but most of them require complex calculations.The LNZN model(a simplified model named by the proposers)simplifies the human model and facilitates ...There are many theories and tools for human or robot motion simulation,but most of them require complex calculations.The LNZN model(a simplified model named by the proposers)simplifies the human model and facilitates simulation of the Ground Reaction Force(GRF)of body landing by spring damping model and ignoring joint rotation movements,which can reduce the amount of computation obviously.In this paper,the LNZN model of human running is selected as the basis and is modified to obtain the LNZN model of a robot,which expands the application of the LNZN model.According to the structure of the human foot,a foot structure is then added to the simplified model to reduce the GRF.We also applied driving forces to the new model to simulate the whole high jump motion of the robot to expand the functions of the LNZN model.The obtained GRF data were anastomotic to the actual experimental results.In addition,the effects of variables,such as the mass,hardness,and damping,of the foot on the GRF at the moment of landing were also explored.Finally,based on the guidelines obtained for the design of the robot’s foot structure,we fabricated new robot’s feet and installed them on the actual robot and achieved a better cushioning effect than the original foot in experiments.展开更多
The Ground Cover Rice Production System(GCRPS)has considerable potential for securing rice production in hilly areas.However,its impact on yields and nitrogen(N)fates remains uncertain under varying rainfall condition...The Ground Cover Rice Production System(GCRPS)has considerable potential for securing rice production in hilly areas.However,its impact on yields and nitrogen(N)fates remains uncertain under varying rainfall conditions.A two-year field experiment(2021–2022)was conducted in Ziyang,Sichuan Province,located in the hilly areas of Southwest China.The experiment included two cultivation methods:conventional flooding paddy(Paddy,W1)and GCRPS(W2).These methods were combined with three N management practices:N1(no-N fertilizer),N2(135 kg/hm^(2)urea as a base fertilizer in both W1 and W2),and N3(135 kg/hm^(2)urea with split application for W1 and 67.5 kg/hm^(2)urea and chicken manure separately for W2).The WHCNS(Soil Water Heat Carbon Nitrogen Simulator)model was calibrated and validated to simulate ponding water depth,soil water storage,soil mineral N content,leaf area index,aboveground dry matter,crop N uptake,and rice yield.Subsequently,this model was used to simulate the responses of rice yield and N fates to GCRPS under different types of precipitation years using meteorological data from 1980 to 2018.The results indicated that the WHCNS model performed well in simulating crop growth and N fates for both Paddy and GCRPS.Compared with Paddy,GCRPS reduced N leaching(35.1%–54.9%),ammonia volatilization(0.7%–13.6%),N runoff(71.1%–83.5%),denitrification(3.8%–6.7%),and total N loss(33.8%–56.9%)for all precipitation year types.However,GCRPS reduced crop N uptake and yield during wet years,while increasing crop N uptake and yield during dry and normal years.Fertilizer application reduced the stability and sustainability of rice yield in wet years,but increased the stability and sustainability of rice yield in dry and normal years.In conclusion,GCRPS is more suitable for normal and dry years in the study region,leading to increased rice yield and reduced N loss.展开更多
In this paper,a new approach called the Eulerian species method was proposed for simulating the convective and/or boiling heat transfer of nanofluids.The movement of nanoparticles in nanofluids is tracked by the speci...In this paper,a new approach called the Eulerian species method was proposed for simulating the convective and/or boiling heat transfer of nanofluids.The movement of nanoparticles in nanofluids is tracked by the species transport equation,and the boiling process of nanofluids is computed by the Eulerian multiphase method coupled with the RPI boiling model.The validity of the species transport equation for simulating nanoparticles movement was verified by conducting a simulation of nanofluids convective heat transfer.Simulation results of boiling heat transfer of nanofluids were obtained by using the commercial CFD software ANSYS Fluent and compared with experimental data and results from another numerical method(Eulerian three-phase model).Good agreement with experimental data was achieved,and it was proved the Eulerian species method is better than the Eulerian three-phase model since it can give better simulation results with higher accuracy but needs fewer computation resources.展开更多
The objective of this paper is to present a new method for designing absorbing or non-reflective boundary conditions (ABC) or (NRBC), illustrated by the case study of the modelling of a solid body in water, specifical...The objective of this paper is to present a new method for designing absorbing or non-reflective boundary conditions (ABC) or (NRBC), illustrated by the case study of the modelling of a solid body in water, specifically the capillary gravity waves generated by its motion at the surface. The study analyses the flow of an inviscid, barotropic, and compressible fluid around the stationary solid body. The dynamic behaviour of the fluid is analysed using a two-dimensional coupled Neumann-Kelvin model extended with capillarity and inertia terms. For computational purposes, it is necessary to truncate the unbounded spatial domain with artificial boundaries and then introduce appropriate absorbing boundary conditions. The propagation of short wavelength waves in a convective fluid medium with significant differences in properties between the interior and the surface of the fluid presents a number of difficulties in the design of these conditions. The results are illustrated numerically and commented upon.展开更多
Learning with noisy labels aims to train neural networks with noisy labels.Current models handle instance-inde-pendent label noise(IIN)well;however,they fall short with real-world noise.In medical image classification...Learning with noisy labels aims to train neural networks with noisy labels.Current models handle instance-inde-pendent label noise(IIN)well;however,they fall short with real-world noise.In medical image classification,atypical samples frequently receive incorrect labels,rendering instance-dependent label noise(IDN)an accurate representa-tion of real-world scenarios.However,the current IDN approaches fail to consider the typicality of samples,which hampers their ability to address real-world label noise effectively.To alleviate the issues,we introduce typicality-and instance-dependent label noise(TIDN)to simulate real-world noise and establish a TIDN-combating framework to combat label noise.Specifically,we use the sample’s distance to decision boundaries in the feature space to repre-sent typicality.The TIDN is then generated according to typicality.We establish a TIDN-attention module to combat label noise and learn the transition matrix from latent ground truth to the observed noisy labels.A recursive algorithm that enables the network to make correct predictions with corrections from the learned transition matrix is proposed.Our experiments demonstrate that the TIDN simulates real-world noise more closely than the existing IIN and IDN.Furthermore,the TIDN-combating framework demonstrates superior classification performance when training with simulated TIDN and actual real-world noise.展开更多
This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stif...This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stiffness was treated as the sum of the spindle modal stiffness and the framework elastic stiffness, based on a novel concept that magnitude of preloads can be controlled by measuring the resonant frequency of a spindle system. By employing an example of a certain type of aircraft simulating rotary table, the modal stiffness was measured on the Agilent 35670A Dynamic Signal Analyzer by experimental modal analysis. The equivalent elastic stiffness was simulated by both finite element analysis in ANSYS? and a curve fitting in MATLAB?. Results showed that the static preloading stiffness of the spindle was 7.2125×107 N/m, and that the optimal preloading force was 120.0848 N. Practical application proved the feasibility of our method.展开更多
A dual-CCD simulating human eyes and neck (DSHEN) vision system is putforward. Its structure and principle are introduced. The DSREN vision system can perform somemovements simulating human eyes and neck by means of f...A dual-CCD simulating human eyes and neck (DSHEN) vision system is putforward. Its structure and principle are introduced. The DSREN vision system can perform somemovements simulating human eyes and neck by means of four rotating joints, and realize preciseobject recognizing and distance measuring in all orientations. The mathematic model of the DSHENvision system is built, and its movement equation is solved. The coordinate error and measureprecision affected by the movement parameters are analyzed by means of intersection measuringmethod. So a theoretic foundation for further research on automatic object recognizing and precisetarget tracking is provided.展开更多
This paper presents research into applying virtual environment (VE) technology to supply chain management (SCM). Our research work has employed virtual manufacturing environments to represent supply chain nodes to sim...This paper presents research into applying virtual environment (VE) technology to supply chain management (SCM). Our research work has employed virtual manufacturing environments to represent supply chain nodes to simulate processes and activities in supply chain management. This will enable those who are involved in these processes and activities to gain an intuitive understanding of them, so as to design robust supply chains and make correct decisions at the right time. A framework system and its hierarchical structure for visualising and simulating supply chains in virtual environments are reported and detailed in this paper.展开更多
Recent years have witnessed the booming of online social network and social media platforms,which leads to a state of information explosion.Though extensive efforts have been made by publishers to struggle for the lim...Recent years have witnessed the booming of online social network and social media platforms,which leads to a state of information explosion.Though extensive efforts have been made by publishers to struggle for the limited attention of audiences,still,only a few of information items will be received and digested.Therefore,for simulating the information propagation process,competition among propagating items should be considered,which has been largely ignored by prior works on propagation modeling.One possible reason may be that,it is almost impossible to identify the influence of propagation background from real diffusion data.To that end,in this paper,we design a comprehensive framework to simulate the propagation process with the characteristics of user behaviors and network topology.Specifically,we propose a propagation background simulating(PBS)algorithm to simulate the propagation background by using users′behavior dynamics and out-degree.Along this line,an ICPB(independent cascade with propagation background)model is adapted to relieve the impact of propagation background by using users′in-degree.Extensive experiments on kinds of synthetic and real networks have demonstrated the effectiveness of our methods.展开更多
Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf ph...Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf photosynthesis, three numerical sensitivity experiments were carried out. We simulated the sing le leaf net CO2 assimilation, which acts as a function of different light, carbo n dioxide and temperature conditions. The relationships between leaf net photosy nthetic rate of C3 and C4 plant with CO2 concentration intercellular, leaf tempe rature, and photosynthetic active radiation (PAR) were presented, respectively. The results show the numerical experiment may indicate the main characteristic o f plant photosynthesis in C3 and C4 plant, and further can be used to integrate with the regional climate model and act as land surface process scheme, and bett er understand the interaction between vegetation and atmosphere.展开更多
The four-dimensional(4D) printing technology, as a combination of additive manufacturing and smart materials, has attracted increasing research interest in recent years. The bilayer structures printed with smart mater...The four-dimensional(4D) printing technology, as a combination of additive manufacturing and smart materials, has attracted increasing research interest in recent years. The bilayer structures printed with smart materials using this technology can realize complicated deformation under some special stimuli due to the material properties.The deformation prediction of bilayer structures can make the design process more rapid and thus is of great importance. However, the previous works on deformation prediction of bilayer structures rarely study the complicated deformations or the influence of the printing process on deformation. Thus, this paper proposes a new method to predict the complicated deformations of temperature-sensitive 4D printed bilayer structures,in particular to the bilayer structures based on temperature-driven shape-memory polymers(SMPs) and fabricated using the fused deposition modeling(FDM) technology. The programming process to the material during printing is revealed and considered in the simulation model. Simulation results are compared with experiments to verify the validity of the method. The advantages of this method are stable convergence and high efficiency,as the three-dimensional(3D) problem is converted to a two-dimensional(2D) problem.The simulation parameters in the model can be further associated with the printing parameters, which shows good application prospect in 4D printed bilayer structure design.展开更多
In the developing phase of typhoon formation, the spiral belt partly emerges in satellite cloud images. This research starts from images and moves on to graphics and then to representation and recognition. Following t...In the developing phase of typhoon formation, the spiral belt partly emerges in satellite cloud images. This research starts from images and moves on to graphics and then to representation and recognition. Following this route, local spiral cloud belt is segmented from the raw images using image segmentation, the spiral information is extracted using mathematic morphology, and local spiral curves are detected using Hough transformation. The problem of center locating of developing typhoon has finally been solved through a search algorithm of spiral curve. For No. 99082008 cloud image, the result produced by the algorithm in this paper is at 122..3 degree west longitude, 117.5 degree north latitude. The real typhoon center location was at 122.4 degree west longitude, 18 degree north latitude.展开更多
Through system analysis of typical explosive trains in various fuses, physical and correspondent mathematical models of typical explosive trains are established, based on mass conservation, momentum conservation, ener...Through system analysis of typical explosive trains in various fuses, physical and correspondent mathematical models of typical explosive trains are established, based on mass conservation, momentum conservation, energy conservation and so on. MAZE and DYNA2D program is used to dispose these models and results of the simulating of elements of explosive trains in a typical fuse are obtained. It is helpful for designing fuses.展开更多
With Visual C++6.0 as the language,following the traditional waterfall model and the software engineering theory,utilizing the technique of the dialog box,picture synthesis in VC,the writers present the developing of ...With Visual C++6.0 as the language,following the traditional waterfall model and the software engineering theory,utilizing the technique of the dialog box,picture synthesis in VC,the writers present the developing of the woven fabric CAD system under the environment of Windows98.The system includes weave designing,yarn simulating,color matching,han- dling hand sample fabric and the testing effect. The basic methods and effect evaluation have been discussed and developed for the weave designing,yarn appearance simulat- ing and fabric color matching,as well as handling hand sample states the image processing,such as DIB(Device-independent bitmap);meanwhile,the developed system has been tested and run in actual design and textile mill trials.The operated results show that the system runs steadily,efficiently and smart,it can be widely used in yarn and fabric design by using with the merits of convenience,celerity and nicety in shortening the developing periods of product;additionally,it provides in fact a new ap- proach to technical design for textile mills.展开更多
Barchan dune is one of the basic forms of eolian landform, it is usually moulded by highconcentration nonsaturated windsand flow. The formation process of barchan dune begins from “wavegrain duality” of windsand mov...Barchan dune is one of the basic forms of eolian landform, it is usually moulded by highconcentration nonsaturated windsand flow. The formation process of barchan dune begins from “wavegrain duality” of windsand movement, and goes through two developmental stages of sand material accumulating (highconcertration saturated windsand flow) and dune form moulding (highconcentration nonsaturated windsand flow), i.e. the processes of dissipative increase and dispersive decrease. The scattered single barchan dunes on nonsandy bed surface have obvious characteristics of mobility and unstability (not including barchan sand hill). The formation of barchan dune in wind tunnel (its dune scale is one order of magnitude larger than sand ripple scale) is helpful to know the formation mechanism of barchan dunes.展开更多
基金supported by the Kunming University of Science and Technology“Double First-Class”Joint Special Project(Grant No.202101BE070001-011)Yunnan Fundamental Research Projects(202201BE070001-008,202201AT070192)+5 种基金National Natural Science Foundation of China(52402077)Shaanxi Province Key R&D Program(2021ZDLGY11-08)Open Project of Shaanxi Laboratory(2021SXsyS01-05)Open Project of Yunnan Precious Metals Laboratory(YPML-2023050240)National Natural Science Foundation of China(Grant No.52462009)Yunnan Fundamental Research Projects(Grant Nos.202201AT070192,202101BE070001-011).
文摘The deep potential(DP)is an innovative approach based on deep learning that uses ab initio calculation data derived from density functional theory(DFT),to create high-accuracy potential functions for various materials.Platinum(Pt)is a rare metal with significant potential in energy and catalytic applications,However,there are challenges in accurately capturing its physical properties due to high experimental costs and the limitations of traditional empirical methods.This study employs deep learning methods to construct high-precision potential models for single-element systems of Pt and validates their predictive performance in complex environments.The newly developed DP is highly consistent with DFT results in predicting the stable phases,lattice constants,surface energies,and phonons dispersion relations of Pt,demonstrating outstanding quantum-level accuracy.Additionally,the complex phase transitions and domain formations of Pt are extensively and quantitatively analyzed.Molecular dynamic simulations utilizing the DP approach show that Pt’s face-centered cubic(FCC)structure undergoes a phase transition from solid to liquid at its melting point of 1986 K,this is in close agreement with the experimental value of 2041.5 K.Increased temperature enhances the diffusion of Pt atoms,with a self-diffusion coefficient of 1.17×10-11 m2/s at the melting point,comparable to that of other FCC metals.This result can be utilized for the precise analysis of the fundamental properties of the rare metal Pt at the microscopic scale,and it facilitates the development of binary or multi-component deep potential models that include Pt.
基金the support of National Natural Science Foundation of China(Grant Numbers 52192675 and 52378541)。
文摘Researching and comprehending the characteristics of destructive seismic motions is essential for the seismic design of critical infrastructure.This study employs historical data from the M 7.5 earthquake that occurred in 1850 to simulate the impacts of a M 7.5 event on hydropower stations located in proximity to Xichang.Key factors taken into account in the simulation of seismic motion encompass uncertainties,mixed-source models,and the placement of asperities.Through these simulations,we acquired the peak ground acceleration(PGA),acceleration time histories,and acceleration response spectra for the hydropower facilities affected by the earthquake.To perform a comprehensive analysis,we utilized a multi-scenario stochastic finite fault simulation method to estimate parameters including the minimum,average,and maximum values of PGA and pseudo-spectral acceleration(PSA)response spectra.Additionally,we assessed the 50^(th),84^(th),and 95^(th)percentiles values of the peak ground acceleration and pseudo-spectral acceleration response spectra.The simulation results also include peak ground acceleration field maps and peak ground velocity(PGV)field maps and intensity distribution maps pertaining to the earthquake.The findings demonstrate that the intensity maps produced through the stochastic finite fault method closely correspond with the intensity contour maps published of historical seismic records.These findings offer significant insights for the seismic safety evaluation and design of the specified hydropower stations.Moreover,this multi-scenario methodology can be effectively utilized for other critical infrastructure projects to derive dependable seismic motion parameters.
文摘1.Introduction Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)is a powerful tool for simulating dense gas-solid reacting flows,which is essential in combustion,metallurgy,and waste management.Traditional methods face challenges in CFD-DEM modeling of dense gas-solid flows due to multi-scale characteristics,limiting resolution and creating simulation bottlenecks.By integrating fluid dynamics and particle behavior,it optimizes industrial processes.This review highlights advancements,applications,and challenges,emphasizing its role in sustainable engineering.
基金supported by a National Science and Technology Major Project(2016ZX05048003).
文摘A new simulation model for the development of gas condensate reservoirs is introduced based on the influence that phase change,non-Darcy flow,and capillary pressure have on the production of gas condensates.The model predicts well performance,including bottom-hole pressure,oil/gas production rate,oil/gas recovery,gaseoil ratio,and the change in produced fluid composition.It also calculates dynamic characters,such as the change of pressure field and oil/gas saturation field during the development of gas condensate reservoirs.The model is applicable to different boundary conditions(both constant-pressure and sealed boundary)and different production modes(both constant-pressure and constant-volume production modes).Model validation attempted using numerical simulation results for sealed boundary conditions with constant-pressure production mode has shown a relatively good match,proving its validity.For constant-pressure boundary conditions with constant-volume production mode,four stages are defined according to the dynamic behavior of production performance in the development of gas condensate reservoirs.
基金The National Natural Science Foundation under contract Nos 52171247,51779022,52071057,and 51709054.
文摘Accurate simulation of the evolution of freak waves by the wave phase focusing method requires accurate linear and nonlinear properties,especially in deep-water conditions.In this paper,we analyze the ability to simulate deep-water focused waves of a two-layer Boussinesq-type(BT)model,which has been shown to have excellent linear and nonlinear performance.To further improve the numerical accuracy and stability,the internal wavegenerated method is introduced into the two-layer Boussinesq-type model.Firstly,the sensitivity of the numerical results to the grid resolution is analyzed to verify the convergence of the model;secondly,the focused wave propagating in two opposite directions is simulated to prove the symmetry of the numerical results and the feasibility of the internal wave-generated method;thirdly,the limiting focused wave condition is simulated to compare and analyze the wave surface and the horizontal velocity of the profile at the focusing position,which is in good agreement with the measured values.Meanwhile the simulation of focused waves in very deep waters agrees well with the measured values,which further demonstrates the capability of the two-layer BT model in simulating focused waves in deep waters.
基金funded by National Natural Science Foundation of China(No.62073041).
文摘There are many theories and tools for human or robot motion simulation,but most of them require complex calculations.The LNZN model(a simplified model named by the proposers)simplifies the human model and facilitates simulation of the Ground Reaction Force(GRF)of body landing by spring damping model and ignoring joint rotation movements,which can reduce the amount of computation obviously.In this paper,the LNZN model of human running is selected as the basis and is modified to obtain the LNZN model of a robot,which expands the application of the LNZN model.According to the structure of the human foot,a foot structure is then added to the simplified model to reduce the GRF.We also applied driving forces to the new model to simulate the whole high jump motion of the robot to expand the functions of the LNZN model.The obtained GRF data were anastomotic to the actual experimental results.In addition,the effects of variables,such as the mass,hardness,and damping,of the foot on the GRF at the moment of landing were also explored.Finally,based on the guidelines obtained for the design of the robot’s foot structure,we fabricated new robot’s feet and installed them on the actual robot and achieved a better cushioning effect than the original foot in experiments.
基金supported by the National Natural Science Foundation of China (Grant No.41977008)the 2115 Talent Development Program of China Agricultural University (Grant No.1191-00109011)。
文摘The Ground Cover Rice Production System(GCRPS)has considerable potential for securing rice production in hilly areas.However,its impact on yields and nitrogen(N)fates remains uncertain under varying rainfall conditions.A two-year field experiment(2021–2022)was conducted in Ziyang,Sichuan Province,located in the hilly areas of Southwest China.The experiment included two cultivation methods:conventional flooding paddy(Paddy,W1)and GCRPS(W2).These methods were combined with three N management practices:N1(no-N fertilizer),N2(135 kg/hm^(2)urea as a base fertilizer in both W1 and W2),and N3(135 kg/hm^(2)urea with split application for W1 and 67.5 kg/hm^(2)urea and chicken manure separately for W2).The WHCNS(Soil Water Heat Carbon Nitrogen Simulator)model was calibrated and validated to simulate ponding water depth,soil water storage,soil mineral N content,leaf area index,aboveground dry matter,crop N uptake,and rice yield.Subsequently,this model was used to simulate the responses of rice yield and N fates to GCRPS under different types of precipitation years using meteorological data from 1980 to 2018.The results indicated that the WHCNS model performed well in simulating crop growth and N fates for both Paddy and GCRPS.Compared with Paddy,GCRPS reduced N leaching(35.1%–54.9%),ammonia volatilization(0.7%–13.6%),N runoff(71.1%–83.5%),denitrification(3.8%–6.7%),and total N loss(33.8%–56.9%)for all precipitation year types.However,GCRPS reduced crop N uptake and yield during wet years,while increasing crop N uptake and yield during dry and normal years.Fertilizer application reduced the stability and sustainability of rice yield in wet years,but increased the stability and sustainability of rice yield in dry and normal years.In conclusion,GCRPS is more suitable for normal and dry years in the study region,leading to increased rice yield and reduced N loss.
基金supported by theResearch Starting Programof Ludong University(Grant No.221/20220045).
文摘In this paper,a new approach called the Eulerian species method was proposed for simulating the convective and/or boiling heat transfer of nanofluids.The movement of nanoparticles in nanofluids is tracked by the species transport equation,and the boiling process of nanofluids is computed by the Eulerian multiphase method coupled with the RPI boiling model.The validity of the species transport equation for simulating nanoparticles movement was verified by conducting a simulation of nanofluids convective heat transfer.Simulation results of boiling heat transfer of nanofluids were obtained by using the commercial CFD software ANSYS Fluent and compared with experimental data and results from another numerical method(Eulerian three-phase model).Good agreement with experimental data was achieved,and it was proved the Eulerian species method is better than the Eulerian three-phase model since it can give better simulation results with higher accuracy but needs fewer computation resources.
文摘The objective of this paper is to present a new method for designing absorbing or non-reflective boundary conditions (ABC) or (NRBC), illustrated by the case study of the modelling of a solid body in water, specifically the capillary gravity waves generated by its motion at the surface. The study analyses the flow of an inviscid, barotropic, and compressible fluid around the stationary solid body. The dynamic behaviour of the fluid is analysed using a two-dimensional coupled Neumann-Kelvin model extended with capillarity and inertia terms. For computational purposes, it is necessary to truncate the unbounded spatial domain with artificial boundaries and then introduce appropriate absorbing boundary conditions. The propagation of short wavelength waves in a convective fluid medium with significant differences in properties between the interior and the surface of the fluid presents a number of difficulties in the design of these conditions. The results are illustrated numerically and commented upon.
基金funded by the National Natural Science Foundation of China,No.62371139the Science and Technology Commission of Shanghai Municipality,Nos.22ZR1404800 and 22DZ1100101.
文摘Learning with noisy labels aims to train neural networks with noisy labels.Current models handle instance-inde-pendent label noise(IIN)well;however,they fall short with real-world noise.In medical image classification,atypical samples frequently receive incorrect labels,rendering instance-dependent label noise(IDN)an accurate representa-tion of real-world scenarios.However,the current IDN approaches fail to consider the typicality of samples,which hampers their ability to address real-world label noise effectively.To alleviate the issues,we introduce typicality-and instance-dependent label noise(TIDN)to simulate real-world noise and establish a TIDN-combating framework to combat label noise.Specifically,we use the sample’s distance to decision boundaries in the feature space to repre-sent typicality.The TIDN is then generated according to typicality.We establish a TIDN-attention module to combat label noise and learn the transition matrix from latent ground truth to the observed noisy labels.A recursive algorithm that enables the network to make correct predictions with corrections from the learned transition matrix is proposed.Our experiments demonstrate that the TIDN simulates real-world noise more closely than the existing IIN and IDN.Furthermore,the TIDN-combating framework demonstrates superior classification performance when training with simulated TIDN and actual real-world noise.
文摘This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stiffness was treated as the sum of the spindle modal stiffness and the framework elastic stiffness, based on a novel concept that magnitude of preloads can be controlled by measuring the resonant frequency of a spindle system. By employing an example of a certain type of aircraft simulating rotary table, the modal stiffness was measured on the Agilent 35670A Dynamic Signal Analyzer by experimental modal analysis. The equivalent elastic stiffness was simulated by both finite element analysis in ANSYS? and a curve fitting in MATLAB?. Results showed that the static preloading stiffness of the spindle was 7.2125×107 N/m, and that the optimal preloading force was 120.0848 N. Practical application proved the feasibility of our method.
基金Aerospace Technology Support Foundation (No.HT2001-zjdx)Science and Technology Development Project of Hangzhou City(No.2001121C42)
文摘A dual-CCD simulating human eyes and neck (DSHEN) vision system is putforward. Its structure and principle are introduced. The DSREN vision system can perform somemovements simulating human eyes and neck by means of four rotating joints, and realize preciseobject recognizing and distance measuring in all orientations. The mathematic model of the DSHENvision system is built, and its movement equation is solved. The coordinate error and measureprecision affected by the movement parameters are analyzed by means of intersection measuringmethod. So a theoretic foundation for further research on automatic object recognizing and precisetarget tracking is provided.
基金This work is partially sponsored by the Cheung Kong Scholars Programme of the People's Republic of China.
文摘This paper presents research into applying virtual environment (VE) technology to supply chain management (SCM). Our research work has employed virtual manufacturing environments to represent supply chain nodes to simulate processes and activities in supply chain management. This will enable those who are involved in these processes and activities to gain an intuitive understanding of them, so as to design robust supply chains and make correct decisions at the right time. A framework system and its hierarchical structure for visualising and simulating supply chains in virtual environments are reported and detailed in this paper.
基金This work was supported by National Natural Science Foundation of China(Nos.91546110,61703386,61727809 and U1605251).
文摘Recent years have witnessed the booming of online social network and social media platforms,which leads to a state of information explosion.Though extensive efforts have been made by publishers to struggle for the limited attention of audiences,still,only a few of information items will be received and digested.Therefore,for simulating the information propagation process,competition among propagating items should be considered,which has been largely ignored by prior works on propagation modeling.One possible reason may be that,it is almost impossible to identify the influence of propagation background from real diffusion data.To that end,in this paper,we design a comprehensive framework to simulate the propagation process with the characteristics of user behaviors and network topology.Specifically,we propose a propagation background simulating(PBS)algorithm to simulate the propagation background by using users′behavior dynamics and out-degree.Along this line,an ICPB(independent cascade with propagation background)model is adapted to relieve the impact of propagation background by using users′in-degree.Extensive experiments on kinds of synthetic and real networks have demonstrated the effectiveness of our methods.
基金Natural Science Foundation of China (Grant No. 39900084)
文摘Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf photosynthesis, three numerical sensitivity experiments were carried out. We simulated the sing le leaf net CO2 assimilation, which acts as a function of different light, carbo n dioxide and temperature conditions. The relationships between leaf net photosy nthetic rate of C3 and C4 plant with CO2 concentration intercellular, leaf tempe rature, and photosynthetic active radiation (PAR) were presented, respectively. The results show the numerical experiment may indicate the main characteristic o f plant photosynthesis in C3 and C4 plant, and further can be used to integrate with the regional climate model and act as land surface process scheme, and bett er understand the interaction between vegetation and atmosphere.
基金the National Natural Science Foundation of China(Nos.52130501 and 52075479)the National Key R&D Program of China(No.2018YFB1700804)。
文摘The four-dimensional(4D) printing technology, as a combination of additive manufacturing and smart materials, has attracted increasing research interest in recent years. The bilayer structures printed with smart materials using this technology can realize complicated deformation under some special stimuli due to the material properties.The deformation prediction of bilayer structures can make the design process more rapid and thus is of great importance. However, the previous works on deformation prediction of bilayer structures rarely study the complicated deformations or the influence of the printing process on deformation. Thus, this paper proposes a new method to predict the complicated deformations of temperature-sensitive 4D printed bilayer structures,in particular to the bilayer structures based on temperature-driven shape-memory polymers(SMPs) and fabricated using the fused deposition modeling(FDM) technology. The programming process to the material during printing is revealed and considered in the simulation model. Simulation results are compared with experiments to verify the validity of the method. The advantages of this method are stable convergence and high efficiency,as the three-dimensional(3D) problem is converted to a two-dimensional(2D) problem.The simulation parameters in the model can be further associated with the printing parameters, which shows good application prospect in 4D printed bilayer structure design.
文摘In the developing phase of typhoon formation, the spiral belt partly emerges in satellite cloud images. This research starts from images and moves on to graphics and then to representation and recognition. Following this route, local spiral cloud belt is segmented from the raw images using image segmentation, the spiral information is extracted using mathematic morphology, and local spiral curves are detected using Hough transformation. The problem of center locating of developing typhoon has finally been solved through a search algorithm of spiral curve. For No. 99082008 cloud image, the result produced by the algorithm in this paper is at 122..3 degree west longitude, 117.5 degree north latitude. The real typhoon center location was at 122.4 degree west longitude, 18 degree north latitude.
文摘Through system analysis of typical explosive trains in various fuses, physical and correspondent mathematical models of typical explosive trains are established, based on mass conservation, momentum conservation, energy conservation and so on. MAZE and DYNA2D program is used to dispose these models and results of the simulating of elements of explosive trains in a typical fuse are obtained. It is helpful for designing fuses.
文摘With Visual C++6.0 as the language,following the traditional waterfall model and the software engineering theory,utilizing the technique of the dialog box,picture synthesis in VC,the writers present the developing of the woven fabric CAD system under the environment of Windows98.The system includes weave designing,yarn simulating,color matching,han- dling hand sample fabric and the testing effect. The basic methods and effect evaluation have been discussed and developed for the weave designing,yarn appearance simulat- ing and fabric color matching,as well as handling hand sample states the image processing,such as DIB(Device-independent bitmap);meanwhile,the developed system has been tested and run in actual design and textile mill trials.The operated results show that the system runs steadily,efficiently and smart,it can be widely used in yarn and fabric design by using with the merits of convenience,celerity and nicety in shortening the developing periods of product;additionally,it provides in fact a new ap- proach to technical design for textile mills.
文摘Barchan dune is one of the basic forms of eolian landform, it is usually moulded by highconcentration nonsaturated windsand flow. The formation process of barchan dune begins from “wavegrain duality” of windsand movement, and goes through two developmental stages of sand material accumulating (highconcertration saturated windsand flow) and dune form moulding (highconcentration nonsaturated windsand flow), i.e. the processes of dissipative increase and dispersive decrease. The scattered single barchan dunes on nonsandy bed surface have obvious characteristics of mobility and unstability (not including barchan sand hill). The formation of barchan dune in wind tunnel (its dune scale is one order of magnitude larger than sand ripple scale) is helpful to know the formation mechanism of barchan dunes.
