The use of local materials is an important part of sustainability for the concrete industry. The declining availability of aggregate resources in many areas has the potential to result in the use of alternative aggreg...The use of local materials is an important part of sustainability for the concrete industry. The declining availability of aggregate resources in many areas has the potential to result in the use of alternative aggregates of lower quality, which can require higher cementitious materials contents, or the use of aggregates shipped from greater distance. In some markets, manufactured sands are replacing natural sands, which can adversely impact the rheology of cementitious mixtures. The use of certain chemical admixtures has been found to often minimize the need to increase cement and water contents in order to overcome the loss of workability that can accompany aggregate sources which feature flat, elongated, angular, and rough particles. In this study, a wide range of natural and manufactured sands were characterized for gradation, mineralogy, shape, texture, and cleanliness, and also evaluated for their effect on mortar rheology with and without a VMA （viscosity modifying agent） type chemical admixture. Use of the VMA is shown to mitigate the rheological effect of certain sands, and in some cases can allow for optimizing the mixture to lower paste contents. In the case of PCP （polycarboxylate）-based superplasticizers, attention is drawn to the increased dose required to achieve target workability versus superplasticizers based on NSFC （naphthalene sulfonate condensate） when swellable clays are present in the very fine fraction of certain aggregate sources. The use of sands with higher fines contents are also shown to increase the workability provided the fines are of appropriate quality.展开更多
It is known that the one-dimensional nonlinear heat equation ut ： f（u）x1x1, f＇（u） 〉 0, u（±∞, t） ： u, u＋ ≠ u- has a unique self-similar solution u（x1/√1＋t）. In multi-dimensional space, （x1/√1＋t...It is known that the one-dimensional nonlinear heat equation ut ： f（u）x1x1, f＇（u） 〉 0, u（±∞, t） ： u, u＋ ≠ u- has a unique self-similar solution u（x1/√1＋t）. In multi-dimensional space, （x1/√1＋t） is called a planar diffusion wave. In the first part of the present paper, it is shown that under some smallness conditions, such a planar diffusion wave is nonlinearly stable for the nonlinear heat equation： ut -△f（u） = 0, x ∈ R^n. The optimal time decay rate is obtained. In the second part of this paper, it is further shown that this planar diffusion wave is still nonlinearly stable for the quasilinear wave equation with damping： utt ＋ ut - △f（u） = 0, x ∈ R^n. The time decay rate is also obtained. The proofs are given by an elementary energy method.展开更多
In this paper, we shall prove that the Koch-Tataru solution u to the incompressible Navier-Stokes equations in Rd satisfies the decay estimates involving some borderline Besov norms with d ≥ 3. Moreover, u has a uniq...In this paper, we shall prove that the Koch-Tataru solution u to the incompressible Navier-Stokes equations in Rd satisfies the decay estimates involving some borderline Besov norms with d ≥ 3. Moreover, u has a unique trajectory which is HSlder continuous with respect to the space variables.展开更多
This paper is dedicated to the study of viscous compressible barotropic fluids in dimension N ≥ 2. We address the question of well-posedness for large data having critical Besov regularity. Our result improves N the...This paper is dedicated to the study of viscous compressible barotropic fluids in dimension N ≥ 2. We address the question of well-posedness for large data having critical Besov regularity. Our result improves N the analysis of Danchin and of the author inasmuch as we may take initial density in BN/p p,1 with 1 ≤ p 〈 ＋∞. Our result relies on a new a priori estimate for the velocity, where we introduce a new unknown called effective velocity to weaken one of the couplings between the density and the velocity. In particular, our result is the first in which we obtain uniqueness without imposing hypothesis on the gradient of the density.展开更多
In 2014, the National Natural Science Foundation of China （NSFC） approved the Jinping Underground Nuclear Astrophysics laboratory （JUNA） project, which aims at direct cross-section measurements of four key stellar...In 2014, the National Natural Science Foundation of China （NSFC） approved the Jinping Underground Nuclear Astrophysics laboratory （JUNA） project, which aims at direct cross-section measurements of four key stellar nuclear reactions right down to the Gamow windows. In order to solve the observed fluorine overabundances in Asymptotic Giant Branch （AGB） stars, measuring the key 19F（p,a）16O reaction at effective burning energies （i.e., at Gamow window） is established as one of the scientific research sub-projects. The present paper describes this sub-project in details, including motivation, status, experimental setup, yield and background estimation, aboveground test, as well as other relevant reactions.展开更多
We present the formal derivation of a new unidirectional model for unsteady mixed flows in nonuniform closed water pipes. In the case of free surface incompressible flows, the FS-model is formally obtained, using form...We present the formal derivation of a new unidirectional model for unsteady mixed flows in nonuniform closed water pipes. In the case of free surface incompressible flows, the FS-model is formally obtained, using formal asymptotic analysis, which is an extension to more classical shallow water models. In the same way, when the pipe is full, we propose the P-model, which describes the evolution of a compressible inviscid flow, close to gas dynamics equations in a nozzle. In order to cope with the transition between a free surface state and a pressured （i.e., compressible） state, we propose a mixed model, the PFS-model, taking into account changes of section and slope variation.展开更多
For the focusing mass-critical NLS iu, ＋ △u = --｜u｜u, it is conjectured that the only global nonscattering solution with ground state mass must be a solitary wave up to symmetries of the equation. In this paper, w...For the focusing mass-critical NLS iu, ＋ △u = --｜u｜u, it is conjectured that the only global nonscattering solution with ground state mass must be a solitary wave up to symmetries of the equation. In this paper, we settle the conjecture for H1 initial data in dimensions d = 2, 3 with spherical symmetry and d ≥ 4 with certain splitting-spherically symmetric initial data.展开更多
We present multicomponent flow models derived from the kinetic theory of gases and investigate the symmetric hyperbolic-parabolic structure of the resulting system of partial differential equations. We address the Cau...We present multicomponent flow models derived from the kinetic theory of gases and investigate the symmetric hyperbolic-parabolic structure of the resulting system of partial differential equations. We address the Cauchy problem for smooth solutions as well as the existence of deflagration waves, also termed anchored waves. We further discuss related models which have a similar hyperbolic-parabolic structure, notably the Saint- Venant system with a temperature equation as well as the equations governing chemical equilibrium flows. We next investigate multicomponent ionized and magnetized flow models with anisotropic transport fluxes which have a different mathematical structure. We finally discuss numerical algorithms specifically devoted to complex chemistry flows, in particular the evaluation of multicomponent transport properties, as well as the impact of multicomponent transport.展开更多
The H@braud-Lequeux model is a model describing the flow of soft glassy material in a simple shear flow configuration. It is given by a kinetic/Fokker-Planck-type equation whose coefficients depend on the shear rate o...The H@braud-Lequeux model is a model describing the flow of soft glassy material in a simple shear flow configuration. It is given by a kinetic/Fokker-Planck-type equation whose coefficients depend on the shear rate of the experiment. In this paper we want to study what happens to the stationary solutions of this model when the shear rate is asymptotically large. In order to do that, we expand the solution of the equation using singular perturbation tools. In the end, we rigorously prove the estimate of Hebraud and Lequeux that the material asymptotically behaves as a Newtonian fluid.展开更多
In this note, we provide a consistant thin layer theory for power law and Bingham incompressible fluids flowing down an inclined plane under the effect of gravity. The derivation of such equations is based on formal a...In this note, we provide a consistant thin layer theory for power law and Bingham incompressible fluids flowing down an inclined plane under the effect of gravity. The derivation of such equations is based on formal asymptotic expansions of solutions of Cauchy momentum equations in the shallow water scaling and in the neighbourhood of steady solutions so that we can close the average equations on the fluid height h and the total discharge rate q.展开更多
Fourier analysis methods and in particular techniques based on Littlewood-Paley decomposition and paraproduct have known a growing interest recently for the study of nonlinear evolutionary equations. In this survey pa...Fourier analysis methods and in particular techniques based on Littlewood-Paley decomposition and paraproduct have known a growing interest recently for the study of nonlinear evolutionary equations. In this survey paper, we explain how these methods may be implemented so as to study the compresible Navier-Stokes equations in the whole space. We shall investigate both the initial value problem in critical Besov spaces and the low Mach number asymptotics.展开更多
With the support of the Origin Exploring of Chinese Civilization Projects (II) and National Natural Science Foundation of China,the close relationship among "pottery coat","kiln sweat" and Chinese ...With the support of the Origin Exploring of Chinese Civilization Projects (II) and National Natural Science Foundation of China,the close relationship among "pottery coat","kiln sweat" and Chinese proto-porcelain glaze were studied,the characteristics and the key foundation of the origin of porcelain glaze were also discussed based on the relevant research results by Shanghai Institute of Ceramics,Chinese Academy of Sciences and Jingdezhen Ceramics Institute.展开更多
This paper is an introduction to the modelling of viscoelastic fluids, with an emphasis on micromacro （or multiscale） models. Some elements of mathematical and numerical analysis are provided. These notes closely fo...This paper is an introduction to the modelling of viscoelastic fluids, with an emphasis on micromacro （or multiscale） models. Some elements of mathematical and numerical analysis are provided. These notes closely follow the lectures delivered by the second author at the Chinese Academy of Science during the Workshop ＂Stress Tensor Effects on Fluid Mechanics＂ in January 2010.展开更多
Along with the development of China's govern- ment performance management and budget reform, and also to further improve the management of NS- FC,performance evaluation of NSFC is necessary. This test introduces t...Along with the development of China's govern- ment performance management and budget reform, and also to further improve the management of NS- FC,performance evaluation of NSFC is necessary. This test introduces the NSF performance assess- ment system,and gives some thoughts about fur- ther development of the performance evaluation of NSFC(National Natural Science Foundation of Chi- na).展开更多
Joint Funds of National Natural Science Foundation of China （ NSFC ） are initiated by different stakeholders, which aim to play a better 9ufdin9 role to support basic research in specific areas and directions. They ...Joint Funds of National Natural Science Foundation of China （ NSFC ） are initiated by different stakeholders, which aim to play a better 9ufdin9 role to support basic research in specific areas and directions. They have formed an important part of the national natural science funding system, which is responsible for advancing science and technology in an expanding frontier. The article would briefly summarize the joint funds strategic goals, programs implementation and achievements in the past decade, and provide a perspective on their future development.展开更多
This paper sums up the fundamental research projects on Vascular Surgery supported by National Natural Science Foundation of China from 1996 to 2000, and presents the experimental results and advances in the aspects o...This paper sums up the fundamental research projects on Vascular Surgery supported by National Natural Science Foundation of China from 1996 to 2000, and presents the experimental results and advances in the aspects of ischemia disease, the formation mechanism and prevention of restenosis, the development of abdominal aorta aneurysm and portal hypertention.展开更多
文摘The use of local materials is an important part of sustainability for the concrete industry. The declining availability of aggregate resources in many areas has the potential to result in the use of alternative aggregates of lower quality, which can require higher cementitious materials contents, or the use of aggregates shipped from greater distance. In some markets, manufactured sands are replacing natural sands, which can adversely impact the rheology of cementitious mixtures. The use of certain chemical admixtures has been found to often minimize the need to increase cement and water contents in order to overcome the loss of workability that can accompany aggregate sources which feature flat, elongated, angular, and rough particles. In this study, a wide range of natural and manufactured sands were characterized for gradation, mineralogy, shape, texture, and cleanliness, and also evaluated for their effect on mortar rheology with and without a VMA （viscosity modifying agent） type chemical admixture. Use of the VMA is shown to mitigate the rheological effect of certain sands, and in some cases can allow for optimizing the mixture to lower paste contents. In the case of PCP （polycarboxylate）-based superplasticizers, attention is drawn to the increased dose required to achieve target workability versus superplasticizers based on NSFC （naphthalene sulfonate condensate） when swellable clays are present in the very fine fraction of certain aggregate sources. The use of sands with higher fines contents are also shown to increase the workability provided the fines are of appropriate quality.
基金Acknowledgements He＇s research is supported in part by National Basic Research Program of China （Grant No. 2006CB805902）. Huang＇ research is supported in part by National Natural Science Foundation of China for Distinguished Youth Scholar （Grant No. 10825102）, NSFC-NSAF （Grant No. 10676037） and National Basic Research Program of China （Grant No. 2006CB805902）.
文摘It is known that the one-dimensional nonlinear heat equation ut ： f（u）x1x1, f＇（u） 〉 0, u（±∞, t） ： u, u＋ ≠ u- has a unique self-similar solution u（x1/√1＋t）. In multi-dimensional space, （x1/√1＋t） is called a planar diffusion wave. In the first part of the present paper, it is shown that under some smallness conditions, such a planar diffusion wave is nonlinearly stable for the nonlinear heat equation： ut -△f（u） = 0, x ∈ R^n. The optimal time decay rate is obtained. In the second part of this paper, it is further shown that this planar diffusion wave is still nonlinearly stable for the quasilinear wave equation with damping： utt ＋ ut - △f（u） = 0, x ∈ R^n. The time decay rate is also obtained. The proofs are given by an elementary energy method.
基金Acknowledgements We are very grateful to the referee＇s suggestions and comments on the improvement of the paper. Part of this work was done when we were visiting Morningside Center of Mathematics, Chinese Academy of Sciences, in the summer of 2010. We appreciate the hospitality and the financial support from the center. P. Zhang is partially supported by National Natural Science Foundation of China （Grant Nos. 10421101 and 10931007）, and the innovation grant from the Chinese Academy of Sciences （Grant No. GJHZ200829）. T. Zhang is partially supported by the Program for New Century Excellent Talents in University, National Natural Science Foundation of China （Grant Nos. 10871175, 10931007 and 10901137）, and the Zhejiang Provincial Natural Science Foundation of China （Grant No. Z6100217）.
文摘In this paper, we shall prove that the Koch-Tataru solution u to the incompressible Navier-Stokes equations in Rd satisfies the decay estimates involving some borderline Besov norms with d ≥ 3. Moreover, u has a unique trajectory which is HSlder continuous with respect to the space variables.
文摘This paper is dedicated to the study of viscous compressible barotropic fluids in dimension N ≥ 2. We address the question of well-posedness for large data having critical Besov regularity. Our result improves N the analysis of Danchin and of the author inasmuch as we may take initial density in BN/p p,1 with 1 ≤ p 〈 ＋∞. Our result relies on a new a priori estimate for the velocity, where we introduce a new unknown called effective velocity to weaken one of the couplings between the density and the velocity. In particular, our result is the first in which we obtain uniqueness without imposing hypothesis on the gradient of the density.
基金supported by the National Natural Science Foundation of China(Grant Nos.114905621149056011135005 and 11321064)
文摘In 2014, the National Natural Science Foundation of China （NSFC） approved the Jinping Underground Nuclear Astrophysics laboratory （JUNA） project, which aims at direct cross-section measurements of four key stellar nuclear reactions right down to the Gamow windows. In order to solve the observed fluorine overabundances in Asymptotic Giant Branch （AGB） stars, measuring the key 19F（p,a）16O reaction at effective burning energies （i.e., at Gamow window） is established as one of the scientific research sub-projects. The present paper describes this sub-project in details, including motivation, status, experimental setup, yield and background estimation, aboveground test, as well as other relevant reactions.
文摘We present the formal derivation of a new unidirectional model for unsteady mixed flows in nonuniform closed water pipes. In the case of free surface incompressible flows, the FS-model is formally obtained, using formal asymptotic analysis, which is an extension to more classical shallow water models. In the same way, when the pipe is full, we propose the P-model, which describes the evolution of a compressible inviscid flow, close to gas dynamics equations in a nozzle. In order to cope with the transition between a free surface state and a pressured （i.e., compressible） state, we propose a mixed model, the PFS-model, taking into account changes of section and slope variation.
基金Acknowledgements The first author is supported in part by National Science Foundation （Grant No. 0908032） and a start up fund in UBC. The second author is supported by an Alfred P. Sloan fellowship.
文摘For the focusing mass-critical NLS iu, ＋ △u = --｜u｜u, it is conjectured that the only global nonscattering solution with ground state mass must be a solitary wave up to symmetries of the equation. In this paper, we settle the conjecture for H1 initial data in dimensions d = 2, 3 with spherical symmetry and d ≥ 4 with certain splitting-spherically symmetric initial data.
文摘We present multicomponent flow models derived from the kinetic theory of gases and investigate the symmetric hyperbolic-parabolic structure of the resulting system of partial differential equations. We address the Cauchy problem for smooth solutions as well as the existence of deflagration waves, also termed anchored waves. We further discuss related models which have a similar hyperbolic-parabolic structure, notably the Saint- Venant system with a temperature equation as well as the equations governing chemical equilibrium flows. We next investigate multicomponent ionized and magnetized flow models with anisotropic transport fluxes which have a different mathematical structure. We finally discuss numerical algorithms specifically devoted to complex chemistry flows, in particular the evaluation of multicomponent transport properties, as well as the impact of multicomponent transport.
文摘The H@braud-Lequeux model is a model describing the flow of soft glassy material in a simple shear flow configuration. It is given by a kinetic/Fokker-Planck-type equation whose coefficients depend on the shear rate of the experiment. In this paper we want to study what happens to the stationary solutions of this model when the shear rate is asymptotically large. In order to do that, we expand the solution of the equation using singular perturbation tools. In the end, we rigorously prove the estimate of Hebraud and Lequeux that the material asymptotically behaves as a Newtonian fluid.
文摘In this note, we provide a consistant thin layer theory for power law and Bingham incompressible fluids flowing down an inclined plane under the effect of gravity. The derivation of such equations is based on formal asymptotic expansions of solutions of Cauchy momentum equations in the shallow water scaling and in the neighbourhood of steady solutions so that we can close the average equations on the fluid height h and the total discharge rate q.
文摘Fourier analysis methods and in particular techniques based on Littlewood-Paley decomposition and paraproduct have known a growing interest recently for the study of nonlinear evolutionary equations. In this survey paper, we explain how these methods may be implemented so as to study the compresible Navier-Stokes equations in the whole space. We shall investigate both the initial value problem in critical Besov spaces and the low Mach number asymptotics.
基金supported by the National Natural Science Foundation of China (Grant Nos.50762006,50962008)the Jiangxi Provincical Department of Eduction (Grant No.LS0908)the Natural Science Foundation of Jiangxi Province (Grant No.2009GQW0014)
文摘With the support of the Origin Exploring of Chinese Civilization Projects (II) and National Natural Science Foundation of China,the close relationship among "pottery coat","kiln sweat" and Chinese proto-porcelain glaze were studied,the characteristics and the key foundation of the origin of porcelain glaze were also discussed based on the relevant research results by Shanghai Institute of Ceramics,Chinese Academy of Sciences and Jingdezhen Ceramics Institute.
文摘This paper is an introduction to the modelling of viscoelastic fluids, with an emphasis on micromacro （or multiscale） models. Some elements of mathematical and numerical analysis are provided. These notes closely follow the lectures delivered by the second author at the Chinese Academy of Science during the Workshop ＂Stress Tensor Effects on Fluid Mechanics＂ in January 2010.
文摘Along with the development of China's govern- ment performance management and budget reform, and also to further improve the management of NS- FC,performance evaluation of NSFC is necessary. This test introduces the NSF performance assess- ment system,and gives some thoughts about fur- ther development of the performance evaluation of NSFC(National Natural Science Foundation of Chi- na).
基金supported by grants from the National Natural Science Foundation of China (grants M1121009)
文摘Joint Funds of National Natural Science Foundation of China （ NSFC ） are initiated by different stakeholders, which aim to play a better 9ufdin9 role to support basic research in specific areas and directions. They have formed an important part of the national natural science funding system, which is responsible for advancing science and technology in an expanding frontier. The article would briefly summarize the joint funds strategic goals, programs implementation and achievements in the past decade, and provide a perspective on their future development.
文摘This paper sums up the fundamental research projects on Vascular Surgery supported by National Natural Science Foundation of China from 1996 to 2000, and presents the experimental results and advances in the aspects of ischemia disease, the formation mechanism and prevention of restenosis, the development of abdominal aorta aneurysm and portal hypertention.
