Non-equilibrium turbulence phenomena have raised great interests in recent years. Significant efforts have been devoted to non-equilibrium turbulence properties in canonical flows, e.g., grid turbulence, turbulent wak...Non-equilibrium turbulence phenomena have raised great interests in recent years. Significant efforts have been devoted to non-equilibrium turbulence properties in canonical flows, e.g., grid turbulence, turbulent wakes, and homogeneous isotropic turbulence(HIT). The non-equilibrium turbulence in non-canonical flows, however, has rarely been studied due to the complexity of the flows. In the present contribution, a directnumerical simulation(DNS) database of a turbulent flow is analyzed over a backwardfacing ramp, the flow near the boundary is demonstrated, and the non-equilibrium turbulent properties of the flow in the wake of the ramp are presented by using the characteristic parameters such as the dissipation coefficient C and the skewness of longitudinal velocity gradient Sk, but with opposite underlying turbulent energy transfer properties. The equation of Lagrangian velocity gradient correlation is examined, and the results show that non-equilibrium turbulence is the result of phase de-coherence phenomena, which is not taken into account in the modeling of non-equilibrium turbulence. These findings are expected to inspire deeper investigation of different non-equilibrium turbulence phenomena in different flow conditions and the improvement of turbulence modeling.展开更多
A description of inverse energy cascade(from small scale to large scale)in homogeneous isotropic turbulence is introduced by using an eigenvalue method.We show a special isotropic turbulence,in which the initial condi...A description of inverse energy cascade(from small scale to large scale)in homogeneous isotropic turbulence is introduced by using an eigenvalue method.We show a special isotropic turbulence,in which the initial condition is constructed by reversing the velocity field in space,i.e.,the time-reversed turbulence.It is shown that the product of eigenvalues of the rate-of-strain tensor can quantitatively describe the backward energy transfer process.This description is consistent to the velocity derivative skewness Sk.However,compared with Sk,it is easier to be obtained,and it is expected to be extended to anisotropic turbulence.Furthermore,this description also works for the resolved velocity field,which means that it can be used in engineering turbulent flows.The description presented here is desired to inspire future investigation for the modeling of the backward energy transfer process and lay the foundation for the accurate prediction of complex flows.展开更多
Silver nanowire(AgNW)networks hold great promises as next-generation flex-ible transparent electrodes(FTEs)for high-performance flexible optoelectronic devices.However,achieving large-area flexible AgNW network electr...Silver nanowire(AgNW)networks hold great promises as next-generation flex-ible transparent electrodes(FTEs)for high-performance flexible optoelectronic devices.However,achieving large-area flexible AgNW network electrodes with low sheet resistance,high optical transmittance,and a smooth surface remains a grand challenge.Here,we report a straightforward and cost-effective roll-to-roll method that includes interface assembly/wetting-induced climbing transfer,nanowelding,and washing processess to fabricate flexible ordered lay-ered AgNW electrodes with high network uniformity.By manipulating the stacking number of the interfacially assembled AgNW monolayer,we can pre-cisely tailor and balance the transparency and the conductivity of the elec-trodes,achieving an exceptional Figure of Merit(FoM)value of 862.Moreover,the ordered layered structure enhances surface smoothness,compared with randomly arranged structures.To highlight the potential of these ordered lay-ered AgNW network electrodes in flexible optoelectronic devices,we success-fully employ them as highly sensitive strain sensors,large-area flexible touch screens,and flexible smart windows.Overall,this work represents a substantial advance toward high-performance FTEs over large areas,opening up exciting opportunities for the development of advanced optoelectronic devices.展开更多
Measuring the characteristics of seawater constituent is in great demand for studies of marine ecosystems and biogeochemistry.However,existing techniques based on remote sensing or in situ samplings present various tr...Measuring the characteristics of seawater constituent is in great demand for studies of marine ecosystems and biogeochemistry.However,existing techniques based on remote sensing or in situ samplings present various tradeoffs with regard to the diversity,synchronism,temporal-spatial resolution,and depth-resolved capacity of their data products.Here,we demonstrate a novel oceanic triple-field-of-view(FOV)high-spectral-resolution lidar(HSRL)with an iterative retrieval approach.This technique provides,for the first time,comprehensive,continuous,and vertical measurements of seawater absorption coefficient,scattering coefficient,and slope of particle size distribution,which are validated by simulations and field experiments.Furthermore,it depicts valuable application potentials in the accuracy improvement of seawater classification and the continuous estimation of depth-resolved particulate organic carbon export.The triple-FOV HSRL with high performance could greatly increase the knowledge of seawater constituents and promote the understanding of marine ecosystems and biogeochemistry.展开更多
Dear Editor,Cardiovascular diseases(CVDs)are the leading cause of death world-wide.Thus,diagnosing and treating CVD remains at the forefront for clinicians while identifying targetable disease mechanisms in preclinica...Dear Editor,Cardiovascular diseases(CVDs)are the leading cause of death world-wide.Thus,diagnosing and treating CVD remains at the forefront for clinicians while identifying targetable disease mechanisms in preclinical models are focus areas for researchers and drug developers(Cai et al.,2022a).The polymorphic protein apolipoprotein E(APOE),central to lipid transport and metabolism,is well-recognized for the role of its isoforms as important predictors for human cardiovascular disorders and neurodegenerative diseases(Tudorache et al.,2017).Plasma APOE is generated primarily from liver hepatocytes,accounting for around 75%of the APOE production from the whole body(Getz and Reardon,2009),and plays important functional roles in monocytes/macrophages,adipocytes,and the central nervous system(Kockx et al.,2018).However,despite the fact that APOE is widely expressed in different mammalian cells,studies on the functional roles of APOE mostly focus on its extracellular secreted form,and the specific effects of APOE,particularly intracellular form in cell types closely related to human cardiovascular diseases are therefore still poorly understood.展开更多
The fast sweeping method is an efficient iterative method for hyperbolic problems. It combines Gauss-Seidel iterations with alternating sweeping orderings. In this paper several parallel implementations of the fast sw...The fast sweeping method is an efficient iterative method for hyperbolic problems. It combines Gauss-Seidel iterations with alternating sweeping orderings. In this paper several parallel implementations of the fast sweeping method are presented. These parallel algorithms are simple and efficient due to the causality of the underlying partial different equations. Numerical examples are used to verify our algorithms.展开更多
Lidar techniques present a distinctive ability to resolve vertical structure of optical properties within the upper water column at both day-and night-time.However,accuracy challenges remain for existing lidar instrum...Lidar techniques present a distinctive ability to resolve vertical structure of optical properties within the upper water column at both day-and night-time.However,accuracy challenges remain for existing lidar instruments due to the ill-posed nature of elastic backscatter lidar retrievals and multiple scattering.Here we demonstrate the high performance of,to the best of our knowledge,the first shipborne oceanic high-spectral-resolution lidar(HSRL)and illustrate a multiple scattering correction algorithm to rigorously address the above challenges in estimating the depth-resolved diffuse attenuation coefficient Kd and the particulate backscattering coefficient bbp at 532 nm.HSRL data were collected during day-and night-time within the coastal areas of East China Sea and South China Sea,which are connected by the Taiwan Strait.Results include vertical profiles from open ocean waters to moderate turbid waters and first lidar continuous observation of diel vertical distribution of thin layers at a fixed station.The root-mean-square relative differences between the HSRL and coincident in situ measurements are 5.6%and 9.1%for Kd and bbp,respectively,corresponding to an improvement of 2.7-13.5 and 4.9-44.1 times,respectively,with respect to elastic backscatter lidar methods.Shipborne oceanic HSRLs with high performance are expected to be of paramount importance for the construction of 3D map of ocean ecosystem.展开更多
This contribution reports the immobilization of polyoxometalate(POM)into poly(4-vinyl pyridine)(P4 VP)brushes and the controlled reduction of silver ions,in-situ generating metal nanoparticles in the brushes.P4 VP bru...This contribution reports the immobilization of polyoxometalate(POM)into poly(4-vinyl pyridine)(P4 VP)brushes and the controlled reduction of silver ions,in-situ generating metal nanoparticles in the brushes.P4 VP brushes were straightforwardly created by UV-assisted photopolymerization of 4-vinyl pyridine(4VP)on silicon or glass substrates.Phosphotungstic acid(H3 PW12 O40),one of the most widely used Keggin-type POM was anchored onto these pyridine moieties through electrostatic interaction,leading to the P4 VP/POM hybrid brushes.The immobilized POM was further reduced to heteropolyblue,which could be used to generate silver nanoparticles in a controlled fashion.AFM,UV-vis and IR characterization indicate that P4 VP brushes not only provide an efficient platform in the controlled preparation of Ag nanoparticles,but also efficiently disperse and stabilize POM,thus preventing the aggregation of the generated Ag nanoparticles.展开更多
We present a compact upwind second order scheme for computing the viscosity solution of the Eikonal equation. This new scheme is based on： 1. the numerical observation that classical first order monotone upwind sche...We present a compact upwind second order scheme for computing the viscosity solution of the Eikonal equation. This new scheme is based on： 1. the numerical observation that classical first order monotone upwind schemes for the Eikonal equation yield numerical upwind gradient which is also first order accurate up to singularities; 2. a remark that partial information on the second derivatives of the solution is known and given in the structure of the Eikonal equation and can be used to reduce the size of the stencil. We implement the second order scheme as a correction to the well known sweeping method but it should be applicable to any first order monotone upwind scheme. Care is needed to choose the appropriate stencils to avoid instabilities.展开更多
We investigate the problem of robust matrix completion with a fraction of observation corrupted by sparsity outlier noise.We propose an algorithmic framework based on the ADMM algorithm for a non-convex optimization,w...We investigate the problem of robust matrix completion with a fraction of observation corrupted by sparsity outlier noise.We propose an algorithmic framework based on the ADMM algorithm for a non-convex optimization,whose objective function consists of an l1 norm data fidelity and a rank constraint.To reduce the computational cost per iteration,two inexact schemes are developed to replace the most time-consuming step in the generic ADMM algorithm.The resulting algorithms remarkably outperform the existing solvers for robust matrix completion with outlier noise.When the noise is severe and the underlying matrix is ill-conditioned,the proposed algorithms are faster and give more accurate solutions than state-of-the-art robust matrix completion approaches.展开更多
This special issue contains eight selected papers from the International Workshop on Modern Optimization and Applications,which was held over the three days,16-18 June 2018 at Academy of Mathematics and Systems Scienc...This special issue contains eight selected papers from the International Workshop on Modern Optimization and Applications,which was held over the three days,16-18 June 2018 at Academy of Mathematics and Systems Science,Chinese Academy of Sciences,Beijing.This conference brought together leading scientists,researchers,and practitioners from the world to exchange and shared ideas and approaches in using modern optimization techniques to model and solve real-world application problems from engineering,industry,and management.A prominent feature of this conference is the mixture of optimization theory,optimization methods,and practice of mathematical optimization.This conference provided a forum for researchers from academia to present their latest theoretical results and for practitioners from industry to describe their real-world applications,and discuss with participants the best way to construct suitable optimization models and how to find algorithms capable of solving these models.展开更多
In this paper,we numerically investigate the effects of surfactant on dropdrop interactions in a 2D shear flow using a coupled level-set and immersed interface approach proposed in(Xu et al.,J.Comput.Phys.,212(2006),...In this paper,we numerically investigate the effects of surfactant on dropdrop interactions in a 2D shear flow using a coupled level-set and immersed interface approach proposed in(Xu et al.,J.Comput.Phys.,212(2006),590–616).We find that surfactant plays a critical and nontrivial role in drop-drop interactions.In particular,we find that the minimum distance between the drops is a non-monotone function of the surfactant coverage and Capillary number.This non-monotonic behavior,which does not occur for clean drops,is found to be due to the presence of Marangoni forces along the drop interfaces.This suggests that there are non-monotonic conditions for coalescence of surfactant-laden drops,as observed in recent experiments of Leal and co-workers.Although our study is two-dimensional,we believe that drop-drop interactions in three-dimensional flows should be qualitatively similar as the Maragoni forces in the near contact region in 3D should have a similar effect.展开更多
We develop an efficient numerical method to compute single slit or double slit diffraction patterns from high frequency wave in inhomogeneous media.We approximate the high frequency asymptotic solution to the Helmholt...We develop an efficient numerical method to compute single slit or double slit diffraction patterns from high frequency wave in inhomogeneous media.We approximate the high frequency asymptotic solution to the Helmholtz equation using the Eulerian Gaussian beam summation proposed in[20,21].The emitted rays from a slit are embedded in the phase space using an open segment.The evolution of this open curve is accurately computed using the recently developed Grid Based Particle Method[24]which results in a very efficient computational algorithm.Following the grid based particle method we proposed in[23,24],we represent the open curve or the open surface by meshless Lagrangian particles sampled according to an underlying fixed Eulerian mesh.The end-points of the open curve are tracked explicitly and consistently with interior particles.To construct the overall wavefield,each of these sampling particles also carry necessary quantities that are obtained by solving advection-reaction equations.Numerical experiments show that the resulting method can model diffraction patterns in inhomogeneous media accurately,even in the occurrence of caustics.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.11572025,11772032,and 51420105008)the National Basic Research Program of China(No.2014CB046405)the U.K.Engineering and Physical Sciences Research Council(EPSRC)(Nos.EP/K024574/1 and EP/L000261/1)
文摘Non-equilibrium turbulence phenomena have raised great interests in recent years. Significant efforts have been devoted to non-equilibrium turbulence properties in canonical flows, e.g., grid turbulence, turbulent wakes, and homogeneous isotropic turbulence(HIT). The non-equilibrium turbulence in non-canonical flows, however, has rarely been studied due to the complexity of the flows. In the present contribution, a directnumerical simulation(DNS) database of a turbulent flow is analyzed over a backwardfacing ramp, the flow near the boundary is demonstrated, and the non-equilibrium turbulent properties of the flow in the wake of the ramp are presented by using the characteristic parameters such as the dissipation coefficient C and the skewness of longitudinal velocity gradient Sk, but with opposite underlying turbulent energy transfer properties. The equation of Lagrangian velocity gradient correlation is examined, and the results show that non-equilibrium turbulence is the result of phase de-coherence phenomena, which is not taken into account in the modeling of non-equilibrium turbulence. These findings are expected to inspire deeper investigation of different non-equilibrium turbulence phenomena in different flow conditions and the improvement of turbulence modeling.
基金the National Natural Science Foundation of China(Nos.12002318 and51976203)the Central Government Guides Local Science and Technology Development Fund Projects(No.YDZX20191400002850)the Science Foundation of North University of China(No.XJJ201929)。
文摘A description of inverse energy cascade(from small scale to large scale)in homogeneous isotropic turbulence is introduced by using an eigenvalue method.We show a special isotropic turbulence,in which the initial condition is constructed by reversing the velocity field in space,i.e.,the time-reversed turbulence.It is shown that the product of eigenvalues of the rate-of-strain tensor can quantitatively describe the backward energy transfer process.This description is consistent to the velocity derivative skewness Sk.However,compared with Sk,it is easier to be obtained,and it is expected to be extended to anisotropic turbulence.Furthermore,this description also works for the resolved velocity field,which means that it can be used in engineering turbulent flows.The description presented here is desired to inspire future investigation for the modeling of the backward energy transfer process and lay the foundation for the accurate prediction of complex flows.
基金supported by the National Natural Science Foundation of China(nos.21988102 and 22305026)the China Postdoctoral Science Foundation(2019M650433).
文摘Silver nanowire(AgNW)networks hold great promises as next-generation flex-ible transparent electrodes(FTEs)for high-performance flexible optoelectronic devices.However,achieving large-area flexible AgNW network electrodes with low sheet resistance,high optical transmittance,and a smooth surface remains a grand challenge.Here,we report a straightforward and cost-effective roll-to-roll method that includes interface assembly/wetting-induced climbing transfer,nanowelding,and washing processess to fabricate flexible ordered lay-ered AgNW electrodes with high network uniformity.By manipulating the stacking number of the interfacially assembled AgNW monolayer,we can pre-cisely tailor and balance the transparency and the conductivity of the elec-trodes,achieving an exceptional Figure of Merit(FoM)value of 862.Moreover,the ordered layered structure enhances surface smoothness,compared with randomly arranged structures.To highlight the potential of these ordered lay-ered AgNW network electrodes in flexible optoelectronic devices,we success-fully employ them as highly sensitive strain sensors,large-area flexible touch screens,and flexible smart windows.Overall,this work represents a substantial advance toward high-performance FTEs over large areas,opening up exciting opportunities for the development of advanced optoelectronic devices.
基金supported by the National Key Research and Development Program of China(2022YFB3901704)the Excellent Young Scientist Program of Zhejiang Provincial Natural Science Foundation of China(LR19D050001 and LQ23F050011)+5 种基金the Fundamental Research Funds for the Central Universities(2021XZZX019)the National Natural Science Foundation of China(NSFC)(62205289)the Scientific Research Foundation for Talent Introduction of Zhejiang University Ningbo Campus(20201203Z0175 and 20201203Z0177)the Ningbo Natural Science Foundation(2022J153 and 2022J154)the State Key Laboratory of Modern Optical Instrumentation Innovation Programthe Zhejiang University Global Partnership Fund.
文摘Measuring the characteristics of seawater constituent is in great demand for studies of marine ecosystems and biogeochemistry.However,existing techniques based on remote sensing or in situ samplings present various tradeoffs with regard to the diversity,synchronism,temporal-spatial resolution,and depth-resolved capacity of their data products.Here,we demonstrate a novel oceanic triple-field-of-view(FOV)high-spectral-resolution lidar(HSRL)with an iterative retrieval approach.This technique provides,for the first time,comprehensive,continuous,and vertical measurements of seawater absorption coefficient,scattering coefficient,and slope of particle size distribution,which are validated by simulations and field experiments.Furthermore,it depicts valuable application potentials in the accuracy improvement of seawater classification and the continuous estimation of depth-resolved particulate organic carbon export.The triple-FOV HSRL with high performance could greatly increase the knowledge of seawater constituents and promote the understanding of marine ecosystems and biogeochemistry.
基金supported by the National Key Research and Development Program of China(nos.2020YFA0804000,2022YFA1103700,2020YFA0112200,2021YFF1201005,2022YFA1103800,the STI2030-Major Projects-2021ZD0202400)the National Natural Science Foundation of China(nos.81921006,82125011,92149301,92168201,91949209,92049304,92049116,32121001,82192863,82122024,82071588,32000500,82271600,32100937)+7 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(no.XDA16000000)the Program of the Beijing Natural Science Foundation(no.Z190019)CAS Project for Young Scientists in Basic Research(nos.YSBR-076,YSBR-012)The Pilot Project for Public Welfare Development and Reform of Beijing-affliated Medical Research Institutes(no.11000022T000000461062)Youth Innovation Promotion Association of CAS(nos.E1CAZW0401,2022083)Young Elite Scientists Sponsorship Program by CAST(nos.YESS20200012,YESS20210002)the Informatization Plan of Chinese Academy of Sciences(nos.CAS-WX2021SF-0301,CAS-WX2022SDC-XK14,CASWx2021SF-0101)the Tencent Foundation(no.2021-1045).
文摘Dear Editor,Cardiovascular diseases(CVDs)are the leading cause of death world-wide.Thus,diagnosing and treating CVD remains at the forefront for clinicians while identifying targetable disease mechanisms in preclinical models are focus areas for researchers and drug developers(Cai et al.,2022a).The polymorphic protein apolipoprotein E(APOE),central to lipid transport and metabolism,is well-recognized for the role of its isoforms as important predictors for human cardiovascular disorders and neurodegenerative diseases(Tudorache et al.,2017).Plasma APOE is generated primarily from liver hepatocytes,accounting for around 75%of the APOE production from the whole body(Getz and Reardon,2009),and plays important functional roles in monocytes/macrophages,adipocytes,and the central nervous system(Kockx et al.,2018).However,despite the fact that APOE is widely expressed in different mammalian cells,studies on the functional roles of APOE mostly focus on its extracellular secreted form,and the specific effects of APOE,particularly intracellular form in cell types closely related to human cardiovascular diseases are therefore still poorly understood.
基金This work is partially supported by Sloan FoundationNSF DMS0513073+1 种基金ONR grant N00014-02-1-0090DARPA grant N00014-02-1-0603
文摘The fast sweeping method is an efficient iterative method for hyperbolic problems. It combines Gauss-Seidel iterations with alternating sweeping orderings. In this paper several parallel implementations of the fast sweeping method are presented. These parallel algorithms are simple and efficient due to the causality of the underlying partial different equations. Numerical examples are used to verify our algorithms.
基金This study was supported by Excellent Young Scientist Program of Zhejang Provincial Natural Science Foundation of China(LR19D050001)National Key ResearchandDevelopment Programof China(2016YFC1400900)+1 种基金Fundamental Research Funds for the Central Universities(international team)Scientific Research Foundation for Talent Introduction(20201203Z0175,20201203Z0177)of Zhejiang University Ningbo Campus.
文摘Lidar techniques present a distinctive ability to resolve vertical structure of optical properties within the upper water column at both day-and night-time.However,accuracy challenges remain for existing lidar instruments due to the ill-posed nature of elastic backscatter lidar retrievals and multiple scattering.Here we demonstrate the high performance of,to the best of our knowledge,the first shipborne oceanic high-spectral-resolution lidar(HSRL)and illustrate a multiple scattering correction algorithm to rigorously address the above challenges in estimating the depth-resolved diffuse attenuation coefficient Kd and the particulate backscattering coefficient bbp at 532 nm.HSRL data were collected during day-and night-time within the coastal areas of East China Sea and South China Sea,which are connected by the Taiwan Strait.Results include vertical profiles from open ocean waters to moderate turbid waters and first lidar continuous observation of diel vertical distribution of thin layers at a fixed station.The root-mean-square relative differences between the HSRL and coincident in situ measurements are 5.6%and 9.1%for Kd and bbp,respectively,corresponding to an improvement of 2.7-13.5 and 4.9-44.1 times,respectively,with respect to elastic backscatter lidar methods.Shipborne oceanic HSRLs with high performance are expected to be of paramount importance for the construction of 3D map of ocean ecosystem.
基金The financial support of this work by Department of Science and Technology of Jilin Province(Nos.20180101196JC and20180101170JC)
文摘This contribution reports the immobilization of polyoxometalate(POM)into poly(4-vinyl pyridine)(P4 VP)brushes and the controlled reduction of silver ions,in-situ generating metal nanoparticles in the brushes.P4 VP brushes were straightforwardly created by UV-assisted photopolymerization of 4-vinyl pyridine(4VP)on silicon or glass substrates.Phosphotungstic acid(H3 PW12 O40),one of the most widely used Keggin-type POM was anchored onto these pyridine moieties through electrostatic interaction,leading to the P4 VP/POM hybrid brushes.The immobilized POM was further reduced to heteropolyblue,which could be used to generate silver nanoparticles in a controlled fashion.AFM,UV-vis and IR characterization indicate that P4 VP brushes not only provide an efficient platform in the controlled preparation of Ag nanoparticles,but also efficiently disperse and stabilize POM,thus preventing the aggregation of the generated Ag nanoparticles.
基金partially supported by ONR Grant N00014-02-1-0090ARO MURI Grant W911NF-07-1-0185NSF Grant DMS0811254
文摘We present a compact upwind second order scheme for computing the viscosity solution of the Eikonal equation. This new scheme is based on： 1. the numerical observation that classical first order monotone upwind schemes for the Eikonal equation yield numerical upwind gradient which is also first order accurate up to singularities; 2. a remark that partial information on the second derivatives of the solution is known and given in the structure of the Eikonal equation and can be used to reduce the size of the stencil. We implement the second order scheme as a correction to the well known sweeping method but it should be applicable to any first order monotone upwind scheme. Care is needed to choose the appropriate stencils to avoid instabilities.
基金JL was supported by China Postdoctoral Science Foundation grant No.2017M620589JFC was supported in part by Hong Kong Research Grant Council(HKRGC)grants 16300616 and 16306317HK Zhao was supported in part by NSF grants DMS-1418422 and DMS-1622490.
文摘We investigate the problem of robust matrix completion with a fraction of observation corrupted by sparsity outlier noise.We propose an algorithmic framework based on the ADMM algorithm for a non-convex optimization,whose objective function consists of an l1 norm data fidelity and a rank constraint.To reduce the computational cost per iteration,two inexact schemes are developed to replace the most time-consuming step in the generic ADMM algorithm.The resulting algorithms remarkably outperform the existing solvers for robust matrix completion with outlier noise.When the noise is severe and the underlying matrix is ill-conditioned,the proposed algorithms are faster and give more accurate solutions than state-of-the-art robust matrix completion approaches.
文摘This special issue contains eight selected papers from the International Workshop on Modern Optimization and Applications,which was held over the three days,16-18 June 2018 at Academy of Mathematics and Systems Science,Chinese Academy of Sciences,Beijing.This conference brought together leading scientists,researchers,and practitioners from the world to exchange and shared ideas and approaches in using modern optimization techniques to model and solve real-world application problems from engineering,industry,and management.A prominent feature of this conference is the mixture of optimization theory,optimization methods,and practice of mathematical optimization.This conference provided a forum for researchers from academia to present their latest theoretical results and for practitioners from industry to describe their real-world applications,and discuss with participants the best way to construct suitable optimization models and how to find algorithms capable of solving these models.
基金support by a research fund from Xiangtan University.Z.Li was partially supported by US ARO grants 56349-MA,AFSOR grant FA9550-09-1-0520NSF grant DMS-0911434support of the National Science Foundation,Division of Mathematical Sciences.H.Zhao is partially supported by NSF grant DMS0811254.
文摘In this paper,we numerically investigate the effects of surfactant on dropdrop interactions in a 2D shear flow using a coupled level-set and immersed interface approach proposed in(Xu et al.,J.Comput.Phys.,212(2006),590–616).We find that surfactant plays a critical and nontrivial role in drop-drop interactions.In particular,we find that the minimum distance between the drops is a non-monotone function of the surfactant coverage and Capillary number.This non-monotonic behavior,which does not occur for clean drops,is found to be due to the presence of Marangoni forces along the drop interfaces.This suggests that there are non-monotonic conditions for coalescence of surfactant-laden drops,as observed in recent experiments of Leal and co-workers.Although our study is two-dimensional,we believe that drop-drop interactions in three-dimensional flows should be qualitatively similar as the Maragoni forces in the near contact region in 3D should have a similar effect.
基金supported in part by the RGC under Grant DAG09/10.SC02supported in part by the ONR grant N00014-02-1-0090in part by the NSF grant DMS0811254.
文摘We develop an efficient numerical method to compute single slit or double slit diffraction patterns from high frequency wave in inhomogeneous media.We approximate the high frequency asymptotic solution to the Helmholtz equation using the Eulerian Gaussian beam summation proposed in[20,21].The emitted rays from a slit are embedded in the phase space using an open segment.The evolution of this open curve is accurately computed using the recently developed Grid Based Particle Method[24]which results in a very efficient computational algorithm.Following the grid based particle method we proposed in[23,24],we represent the open curve or the open surface by meshless Lagrangian particles sampled according to an underlying fixed Eulerian mesh.The end-points of the open curve are tracked explicitly and consistently with interior particles.To construct the overall wavefield,each of these sampling particles also carry necessary quantities that are obtained by solving advection-reaction equations.Numerical experiments show that the resulting method can model diffraction patterns in inhomogeneous media accurately,even in the occurrence of caustics.
