The co-firing of coal and biomass in oxy-fuel fluidized beds is one of the most promising technologies for capturing CO2.This technology has attracted wide attention from academia and industry in recent years as a neg...The co-firing of coal and biomass in oxy-fuel fluidized beds is one of the most promising technologies for capturing CO2.This technology has attracted wide attention from academia and industry in recent years as a negative emission method to capture CO2 produced by carbon contained in biomass.In the past decades,many studies have been carried out regarding experiments and numerical simulations under oxy-fuel combustion conditions.This paper firstly briefly discusses the techno-economic viability of the biomass and coal co-firing with oxycombustion and then presents a review of recent advancements involving experimental research and computational fluid dynamics(CFD)simulations in this field.Experimental studies on mechanism research,such as thermogravimetric analysis and tube furnace experiments,and fluidized bed experiments based on oxy-fuel fluidized beds with different sizes as well as the main findings,are summarized as a part of this review.It has been recognized that CFD is a useful approach for understanding the behaviors of the co-firing of coal and biomass in oxyfuel fluidized beds.We summarize a recent survey of published CFD research on oxy-fuel fluidized bed combustion,which categorized into Eulerian and Lagrangian methods.Finally,we discuss the challenges and interests for future research.展开更多
Based on the nonlocal theory and Mindlin plate theory,the governing equations(i.e.,a system of partial differential equations(PDEs)for bending problem)of magnetoelectroelastic(MEE)nanoplates resting on the Pasternak e...Based on the nonlocal theory and Mindlin plate theory,the governing equations(i.e.,a system of partial differential equations(PDEs)for bending problem)of magnetoelectroelastic(MEE)nanoplates resting on the Pasternak elastic foundation are first derived by the variational principle.The polynomial particular solutions corresponding to the established model are then obtained and further employed as basis functions with the method of particular solutions(MPS)to solve the governing equations numerically.It is confirmed that for the present bending model,the new solution strategy possesses more general applicability and superior flexibility in the selection of collocation points.The effects of different boundary conditions,applied loads,and geometrical shapes on the bending properties of MEE nanoplates are evaluated by using the developed method.Some important conclusions are drawn,which should be helpful for the design and applications of electromagnetic nanoplate structures.展开更多
A series of Mg_(2-x)Nd_xNi (x=0.05, 0.1, 0.2, 0.3) alloys and Mg_(1.95)RE_(0.05)Ni (RE= La, Ce, Pr, Nd, Y) ternary alloys were prepared by ball milling of mixted powder of Mg,Ni,RE and sintering under the protection o...A series of Mg_(2-x)Nd_xNi (x=0.05, 0.1, 0.2, 0.3) alloys and Mg_(1.95)RE_(0.05)Ni (RE= La, Ce, Pr, Nd, Y) ternary alloys were prepared by ball milling of mixted powder of Mg,Ni,RE and sintering under the protection of argon. XRD analysis shows that Mg_(2-x)Nd_xNi (x=0.05, 0.1) and Mg_(1.95)RE_(0.05)Ni consist of single phase with the same crystal structure as Mg_2Ni. While three-phase alloys including Mg_2Ni, NdNi and NdMgNi_4 were formed in Mg_(1.8)Nd_(0.2)Ni and Mg_(1.7)Nd_(0.3)Ni alloys respectively. The lattice constants of Mg_2Ni in those ternary alloys were calculated. The decomposition of Mg_2Ni occurs in the milling process of Mg_2Ni and Mg_(1.95)RE_(0.05) Ni alloys respectively. For the latter, another earlier reaction occurs in milling process, which means that atoms of RE are separated from crystal structure of Mg_2Ni and form relevant oxides by combination with oxygen existed in argon atmosphere.展开更多
Background: Life-threatening bleeding is a major cause of trauma-related deaths. Stop the Bleed—Active bleeding control (ABC) program in Hyderabad recently showed that lay first responders can be effectively trained....Background: Life-threatening bleeding is a major cause of trauma-related deaths. Stop the Bleed—Active bleeding control (ABC) program in Hyderabad recently showed that lay first responders can be effectively trained. However, the willingness of high school students to train in bleeding control is unknown. We report Stop the Bleed training needs assessment from high schools in India and estimate the potential multiplier effect. Methods: A cross-sectional survey was conducted from 12 randomly selected schools in Hyderabad. The study was to understand current knowledge, skills and willingness to get trained and respond to life-threatening bleeding from injuries. 107 Participants (35 Teachers and 72 students) were purposively selected for telephonic interviews with a structured questionnaire. Results: Response rate was 93% overall. 80% of participants have never been trained in bleeding control. 84% reported willingness to be trained, train others and help bleeding victims. All the teachers reported that stop the bleed training would be useful in high schools. 70.6% of teachers recommended that training could start from middle school (10 to 15 years), 47% preferred the online training mode. Only 20% of participants had prior training in lifesaving first aid and 32% did not know the number of emergency medical services (EMS). Each trained participant has the potential to train 3 to 4 people at the household level and perhaps more at the community level. Conclusion: The surveyed schools in Hyderabad do not have the knowledge, skills, or training curriculum in Stop the Bleed. Students and teachers are willing to be trained and train others, with great potential for a “multiplier-effect” in the community.展开更多
The aim of this paper is to propose a fast meshless numerical scheme for the simulation of non-linear Schrodinger equations.In the proposed scheme,the implicit-Euler scheme is used for the temporal discretization and ...The aim of this paper is to propose a fast meshless numerical scheme for the simulation of non-linear Schrodinger equations.In the proposed scheme,the implicit-Euler scheme is used for the temporal discretization and the localized method of approximate particular solution(LMAPS)is utilized for the spatial discretization.The multiple-scale technique is introduced to obtain the shape parameters of the multiquadric radial basis function for 2D problems and the Gaussian radial basis function for 3D problems.Six numerical examples are carried out to verify the accuracy and efficiency of the proposed scheme.Compared with well-known techniques,numerical results illustrate that the proposed scheme is of merits being easy-to-program,high accuracy,and rapid convergence even for long-term problems.These results also indicate that the proposed scheme has great potential in large scale problems and real-world applications.展开更多
A localized space-time method of fundamental solutions(LSTMFS)is extended for solving three-dimensional transient diffusion problems in this paper.The interval segmentation in temporal direction is developed for the a...A localized space-time method of fundamental solutions(LSTMFS)is extended for solving three-dimensional transient diffusion problems in this paper.The interval segmentation in temporal direction is developed for the accurate simulation of long-time-dependent diffusion problems.In the LSTMFS,the whole space-time domain with nodes arranged i divided into a series of overlapping subdomains with a simple geometry.In each subdomain,the conventional method of fundamental solutions is utilized and the coefficients associated with the considered domain can be explicitly determined.By calculating a combined sparse matrix system,the value at any node inside the space-time domain can be obtained.Numerical experi-ments demonstrate that high accuracy and efficiency can be simultaneously achieved via the LSTMFS,even for the problems defined on a long-time and quite complex computational domain.展开更多
In this paper,a new formulation is proposed to evaluate the origin intensity factors(OIFs)in the singular boundary method(SBM)for solving 3D potential problems with Dirichlet boundary condition.The SBM is a strong-for...In this paper,a new formulation is proposed to evaluate the origin intensity factors(OIFs)in the singular boundary method(SBM)for solving 3D potential problems with Dirichlet boundary condition.The SBM is a strong-form boundary discretization collocation technique and is mathematically simple,easy-to-program,and free of mesh.The crucial step in the implementation of the SBM is to determine the OIFs which isolate the singularities of the fundamental solutions.Traditionally,the inverse interpolation technique(IIT)is adopted to calculate the OIFs on Dirichlet boundary,which is time consuming for large-scale simulation.In recent years,the new methodology has been developed to efficiently calculate the OIFs on Neumann boundary,but the Dirichlet problem remains an open issue.This study employs the subtracting and adding-back technique based on the integration of the fundamental solution over the whole boundary to develop a new formulation of the OIFs on 3D Dirichlet boundary.Several problems with varied domain shapes and boundary conditions are carried out to validate the effectiveness and feasibility of the proposed scheme in comparison with the SBM based on inverse interpolation technique,the method of fundamental solutions,and the boundary element method.展开更多
This paper presents a new numerical technique for solving initial and bound-ary value problems with unsteady strongly nonlinear advection diffusion reaction(ADR)equations.The method is based on the use of the radial b...This paper presents a new numerical technique for solving initial and bound-ary value problems with unsteady strongly nonlinear advection diffusion reaction(ADR)equations.The method is based on the use of the radial basis functions(RBF)for the approximation space of the solution.The Crank-Nicolson scheme is used for approximation in time.This results in a sequence of stationary nonlinear ADR equations.The equations are solved sequentially at each time step using the proposed semi-analytical technique based on the RBFs.The approximate solution is sought in the form of the analytical expansion over basis functions and contains free parameters.The basis functions are constructed in such a way that the expansion satisfies the boundary conditions of the problem for any choice of the free parameters.The free parameters are determined by substitution of the expansion in the equation and collocation in the solution domain.In the case of a nonlinear equation,we use the well-known procedure of quasilinearization.This transforms the original equation into a sequence of the linear ones on each time layer.The numerical examples confirm the high accuracy and robustness of the proposed numerical scheme.展开更多
This paper presents a study of the mixing/segregation behaviour of particle mixtures in a gas fluidized bed by use of the discrete particle simulation. Spherical particles with diameters 2 mm （jetsam） and 1 mm （flo...This paper presents a study of the mixing/segregation behaviour of particle mixtures in a gas fluidized bed by use of the discrete particle simulation. Spherical particles with diameters 2 mm （jetsam） and 1 mm （flotsam） and density 2 500 kg.m^-3 are used as solid mixtures with different volume fractions. The particles are initially packed uniformly in a rectangular bed and then fluidized by gas uniformly injected at the bottom of the bed. The gas injection velocities vary to cover fixed, partially and fully fluidized bed conditions. Segregation/mixing behaviour is discussed in terms of flow patterns, solid concentration profile and mixing kinetics. The results show that segregation, as a transient fluidization process, is strongly affected by gas injection velocities for a given particle mixture. With the increase of the volume fraction of flotsam, size segregation appears at lower velocities.展开更多
Tissue growth is a driving force of morphological changes in living systems.Whereas the buckling instability is known to play a crutial role for initiating spatial pattern formations in such growing systems,little is ...Tissue growth is a driving force of morphological changes in living systems.Whereas the buckling instability is known to play a crutial role for initiating spatial pattern formations in such growing systems,little is known about the rationale for succeeding morphological changes beyond this instability.In mammalian skin,the dermis has many protrusions toward the epidermis,and the epidermal stem cells are typically found on the tips of these protrusions.Although the initial instability may well be explained by the buckling involving the dermis and the basal layer,which contains proliferative cells,it does not dictate the direction of these protrusions,nor the spatial patterning of epidermal stem cells.Here we introduce a particle-based model of self-replicating cells on a deformable substrate composed of the dermis and the basement membrane,and investigate the relationship between dermal deformation and epidermal stem cell pattering on it.We show that our model reproduces the formation of dermal protrusions directing from the dermis to the epidermis,and preferential epidermal stem cell distributions on the tips of the dermal protrusions,which the basic buckling mechanism fails to explain.We argue that cell-type-dependent adhesion strengths of the cells to the basement membrane are crucial factors influencing these patterns.展开更多
基金supported by the Key Program of the National Natural Science Foundation of China(51736002)the Natural Science Foundation of Jiangsu Province(BK20180386).
文摘The co-firing of coal and biomass in oxy-fuel fluidized beds is one of the most promising technologies for capturing CO2.This technology has attracted wide attention from academia and industry in recent years as a negative emission method to capture CO2 produced by carbon contained in biomass.In the past decades,many studies have been carried out regarding experiments and numerical simulations under oxy-fuel combustion conditions.This paper firstly briefly discusses the techno-economic viability of the biomass and coal co-firing with oxycombustion and then presents a review of recent advancements involving experimental research and computational fluid dynamics(CFD)simulations in this field.Experimental studies on mechanism research,such as thermogravimetric analysis and tube furnace experiments,and fluidized bed experiments based on oxy-fuel fluidized beds with different sizes as well as the main findings,are summarized as a part of this review.It has been recognized that CFD is a useful approach for understanding the behaviors of the co-firing of coal and biomass in oxyfuel fluidized beds.We summarize a recent survey of published CFD research on oxy-fuel fluidized bed combustion,which categorized into Eulerian and Lagrangian methods.Finally,we discuss the challenges and interests for future research.
基金Project supported by the National Natural Science Foundation of China(Nos.11872257 and 11572358)the German Research Foundation(No.ZH 15/14-1)。
文摘Based on the nonlocal theory and Mindlin plate theory,the governing equations(i.e.,a system of partial differential equations(PDEs)for bending problem)of magnetoelectroelastic(MEE)nanoplates resting on the Pasternak elastic foundation are first derived by the variational principle.The polynomial particular solutions corresponding to the established model are then obtained and further employed as basis functions with the method of particular solutions(MPS)to solve the governing equations numerically.It is confirmed that for the present bending model,the new solution strategy possesses more general applicability and superior flexibility in the selection of collocation points.The effects of different boundary conditions,applied loads,and geometrical shapes on the bending properties of MEE nanoplates are evaluated by using the developed method.Some important conclusions are drawn,which should be helpful for the design and applications of electromagnetic nanoplate structures.
文摘A series of Mg_(2-x)Nd_xNi (x=0.05, 0.1, 0.2, 0.3) alloys and Mg_(1.95)RE_(0.05)Ni (RE= La, Ce, Pr, Nd, Y) ternary alloys were prepared by ball milling of mixted powder of Mg,Ni,RE and sintering under the protection of argon. XRD analysis shows that Mg_(2-x)Nd_xNi (x=0.05, 0.1) and Mg_(1.95)RE_(0.05)Ni consist of single phase with the same crystal structure as Mg_2Ni. While three-phase alloys including Mg_2Ni, NdNi and NdMgNi_4 were formed in Mg_(1.8)Nd_(0.2)Ni and Mg_(1.7)Nd_(0.3)Ni alloys respectively. The lattice constants of Mg_2Ni in those ternary alloys were calculated. The decomposition of Mg_2Ni occurs in the milling process of Mg_2Ni and Mg_(1.95)RE_(0.05) Ni alloys respectively. For the latter, another earlier reaction occurs in milling process, which means that atoms of RE are separated from crystal structure of Mg_2Ni and form relevant oxides by combination with oxygen existed in argon atmosphere.
文摘Background: Life-threatening bleeding is a major cause of trauma-related deaths. Stop the Bleed—Active bleeding control (ABC) program in Hyderabad recently showed that lay first responders can be effectively trained. However, the willingness of high school students to train in bleeding control is unknown. We report Stop the Bleed training needs assessment from high schools in India and estimate the potential multiplier effect. Methods: A cross-sectional survey was conducted from 12 randomly selected schools in Hyderabad. The study was to understand current knowledge, skills and willingness to get trained and respond to life-threatening bleeding from injuries. 107 Participants (35 Teachers and 72 students) were purposively selected for telephonic interviews with a structured questionnaire. Results: Response rate was 93% overall. 80% of participants have never been trained in bleeding control. 84% reported willingness to be trained, train others and help bleeding victims. All the teachers reported that stop the bleed training would be useful in high schools. 70.6% of teachers recommended that training could start from middle school (10 to 15 years), 47% preferred the online training mode. Only 20% of participants had prior training in lifesaving first aid and 32% did not know the number of emergency medical services (EMS). Each trained participant has the potential to train 3 to 4 people at the household level and perhaps more at the community level. Conclusion: The surveyed schools in Hyderabad do not have the knowledge, skills, or training curriculum in Stop the Bleed. Students and teachers are willing to be trained and train others, with great potential for a “multiplier-effect” in the community.
基金The authors thank the editor and anonymous reviewers for their constructive comments on the manuscript.The research of the authors was supported by the Natural Science Foundation of Jiangsu Province(No.BK20150795)the Fundamental Research Funds for the Central Universities(No.2018B16714)+3 种基金the National Natural Science Foundation of China(Nos.11702083,51679150,51579153,51739008,51527811)the State Key Laboratory of Mechanics and Control of Mechanical Structures(Nanjing University of Aeronautics and Astronautics)(No.MCMS-0218G01)the National Key R&D Program of China(No.2016YFC0401902)the Fund Project of NHRI(Nos.Y417002,Y417015).
文摘The aim of this paper is to propose a fast meshless numerical scheme for the simulation of non-linear Schrodinger equations.In the proposed scheme,the implicit-Euler scheme is used for the temporal discretization and the localized method of approximate particular solution(LMAPS)is utilized for the spatial discretization.The multiple-scale technique is introduced to obtain the shape parameters of the multiquadric radial basis function for 2D problems and the Gaussian radial basis function for 3D problems.Six numerical examples are carried out to verify the accuracy and efficiency of the proposed scheme.Compared with well-known techniques,numerical results illustrate that the proposed scheme is of merits being easy-to-program,high accuracy,and rapid convergence even for long-term problems.These results also indicate that the proposed scheme has great potential in large scale problems and real-world applications.
基金the Fundamental Research Funds for the Central Universities(Grants B200203009 and B200202126)the Natural Science Foundation of Jiangsu Province(Grant BK20190073)+2 种基金the State Key Laboratory of Acoustics,Chinese Academy of Sciences(Grant SKLA202001)the State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,Shijiazhuang Tiedao University(Grant KF2020-22)the China Postdoctoral Science Foundation(Grants 2017M611669 and 2018T110430).
文摘A localized space-time method of fundamental solutions(LSTMFS)is extended for solving three-dimensional transient diffusion problems in this paper.The interval segmentation in temporal direction is developed for the accurate simulation of long-time-dependent diffusion problems.In the LSTMFS,the whole space-time domain with nodes arranged i divided into a series of overlapping subdomains with a simple geometry.In each subdomain,the conventional method of fundamental solutions is utilized and the coefficients associated with the considered domain can be explicitly determined.By calculating a combined sparse matrix system,the value at any node inside the space-time domain can be obtained.Numerical experi-ments demonstrate that high accuracy and efficiency can be simultaneously achieved via the LSTMFS,even for the problems defined on a long-time and quite complex computational domain.
基金The work described in this paper was supported by the National Science Funds for Distinguished Young Scholars of China(No.11125208)NSFC Funds(Nos.11302069,11372097,11602114 and 11662003)the 111 project under Grant No.B12032.
文摘In this paper,a new formulation is proposed to evaluate the origin intensity factors(OIFs)in the singular boundary method(SBM)for solving 3D potential problems with Dirichlet boundary condition.The SBM is a strong-form boundary discretization collocation technique and is mathematically simple,easy-to-program,and free of mesh.The crucial step in the implementation of the SBM is to determine the OIFs which isolate the singularities of the fundamental solutions.Traditionally,the inverse interpolation technique(IIT)is adopted to calculate the OIFs on Dirichlet boundary,which is time consuming for large-scale simulation.In recent years,the new methodology has been developed to efficiently calculate the OIFs on Neumann boundary,but the Dirichlet problem remains an open issue.This study employs the subtracting and adding-back technique based on the integration of the fundamental solution over the whole boundary to develop a new formulation of the OIFs on 3D Dirichlet boundary.Several problems with varied domain shapes and boundary conditions are carried out to validate the effectiveness and feasibility of the proposed scheme in comparison with the SBM based on inverse interpolation technique,the method of fundamental solutions,and the boundary element method.
基金supported by the Fundamental Research Funds for the Central Universities(No.2018B16714)the National Natural Science Foundation of China(Nos.11702083,11572111,51679150,51579153,51739008,51527811)+5 种基金the State Key Laboratory of Mechanics and Control of Mechanical Structures(Nanjing University of Aeronautics and Astronautics)(No.MCMS-0218G01)the China Postdoctoral Science Foundation(No.2017M611669)the China Postdoctoral Science Special Foundation(No.2018T110430)the Postdoctoral Foundation of Jiangsu Province(No.1701059C)the National Key R&D Program of China(No.2016YFC0401902)the Fund Project of NHRI(Nos.Y417002,Y417015).
文摘This paper presents a new numerical technique for solving initial and bound-ary value problems with unsteady strongly nonlinear advection diffusion reaction(ADR)equations.The method is based on the use of the radial basis functions(RBF)for the approximation space of the solution.The Crank-Nicolson scheme is used for approximation in time.This results in a sequence of stationary nonlinear ADR equations.The equations are solved sequentially at each time step using the proposed semi-analytical technique based on the RBFs.The approximate solution is sought in the form of the analytical expansion over basis functions and contains free parameters.The basis functions are constructed in such a way that the expansion satisfies the boundary conditions of the problem for any choice of the free parameters.The free parameters are determined by substitution of the expansion in the equation and collocation in the solution domain.In the case of a nonlinear equation,we use the well-known procedure of quasilinearization.This transforms the original equation into a sequence of the linear ones on each time layer.The numerical examples confirm the high accuracy and robustness of the proposed numerical scheme.
文摘This paper presents a study of the mixing/segregation behaviour of particle mixtures in a gas fluidized bed by use of the discrete particle simulation. Spherical particles with diameters 2 mm （jetsam） and 1 mm （flotsam） and density 2 500 kg.m^-3 are used as solid mixtures with different volume fractions. The particles are initially packed uniformly in a rectangular bed and then fluidized by gas uniformly injected at the bottom of the bed. The gas injection velocities vary to cover fixed, partially and fully fluidized bed conditions. Segregation/mixing behaviour is discussed in terms of flow patterns, solid concentration profile and mixing kinetics. The results show that segregation, as a transient fluidization process, is strongly affected by gas injection velocities for a given particle mixture. With the increase of the volume fraction of flotsam, size segregation appears at lower velocities.
基金This work was supported by JST CREST Grant Number JPMJCR15D2,Japanthe Cooperative Research Program of“Network Joint Research Center for Materials and Devices”(No.20173006).
文摘Tissue growth is a driving force of morphological changes in living systems.Whereas the buckling instability is known to play a crutial role for initiating spatial pattern formations in such growing systems,little is known about the rationale for succeeding morphological changes beyond this instability.In mammalian skin,the dermis has many protrusions toward the epidermis,and the epidermal stem cells are typically found on the tips of these protrusions.Although the initial instability may well be explained by the buckling involving the dermis and the basal layer,which contains proliferative cells,it does not dictate the direction of these protrusions,nor the spatial patterning of epidermal stem cells.Here we introduce a particle-based model of self-replicating cells on a deformable substrate composed of the dermis and the basement membrane,and investigate the relationship between dermal deformation and epidermal stem cell pattering on it.We show that our model reproduces the formation of dermal protrusions directing from the dermis to the epidermis,and preferential epidermal stem cell distributions on the tips of the dermal protrusions,which the basic buckling mechanism fails to explain.We argue that cell-type-dependent adhesion strengths of the cells to the basement membrane are crucial factors influencing these patterns.
