A new non-hydrostatic numerical model with the three-dimensional Navier-Stokes equations on structured grids was constructed and discussed. The algorithm is based upon a staggered finite difference Crank-Nicholson sch...A new non-hydrostatic numerical model with the three-dimensional Navier-Stokes equations on structured grids was constructed and discussed. The algorithm is based upon a staggered finite difference Crank-Nicholson scheme on a Cartesian grid. The eddy viscosity coefficient was calculated by the efficient k-ε turbulence model. A new surface-layer non-hydrostatic treatment and a local cell bottom treatment were introduced so that the three-dimensional model is fully non-hydrostatic and is free of any hydrostatic assumption. The developed model is second-order accuracy in both time and space when semi-implicit coefficient is set to 0.5. The validity of the present solution algorithm was demonstrated from its application to the three-dimension channel flow and the wave propagation over a submerged bar problems.展开更多
Two independent versions of the RNG based k ε turbulence model in conjunction with the law of the wall have been applied to the numerical simulation of an axisymmetric turbulent impinging jet flow field. The two m...Two independent versions of the RNG based k ε turbulence model in conjunction with the law of the wall have been applied to the numerical simulation of an axisymmetric turbulent impinging jet flow field. The two model predictions are compared with those of the standard k ε model and with the experimental data measured by LDV (Laser Doppler Velocimetry). It shows that the original version of the RNG k ε model with the choice of C ε1 =1.063 can not yield good results, among them the predicted turbulent kinetic energy profiles in the vicinity of the stagnation region are even worse than those predicted by the standard k ε model. However, the new version of RNG k ε model behaves well. This is mainly due to the corrections to the constants C ε1 and C ε2 along with a modification of the production term to account for non equilibrium strain rates in the flow.展开更多
This paper consists of three main parts.One of them is to develop local and global Sobolev interpolation inequalities of any higher order for the nonisotropic Sobolev spaces on stratified nilpotent Lie groups.Despite ...This paper consists of three main parts.One of them is to develop local and global Sobolev interpolation inequalities of any higher order for the nonisotropic Sobolev spaces on stratified nilpotent Lie groups.Despite the extensive research after Jerison’s work[3]on Poincaré-type inequalities for Hrmander’s vector fields over the years,our results given here even in the nonweighted case appear to be new.Such interpolation inequalities have crucial applications to subelliptic or parabolic PDE’s involving vector fields.The main tools to prove such inequalities are approximating the Sobolev func- tions by polynomials associated with the left invariant vector fields on G.Some very useful properties for polynomials associated with the functions are given here and they appear to have independent interests in their own rights.Finding the existence of such polynomials is the second main part of this paper.Main results of these two parts have been announced in the author’s paper in Mathematical Research Letters[38]. The third main part of this paper contains extension theorems on anisotropic Sobolev spaces on stratified groups and their applications to proving Sobolev interpolation inequalities on(εδ)domains. Some results of weighted Sobolev spaces are also given here.We construct a linear extension operator which is bounded on different Sobolev spaces simultaneously.In particular,we are able to construct a bounded linear extension operator such that the derivatives of the extended function can be controlled by the same order of derivatives of the given Sobolev functions.Theorems are stated and proved for weighted anisotropic Sobolev spaces on stratified groups.展开更多
Flood discharge over top outlet of dam is simulated by 2 dimension water air two phase mathematical model. Distribution of dynamic pressure, turbulent kinetic energy (k), turbulent dissipation rate (ε), free wat...Flood discharge over top outlet of dam is simulated by 2 dimension water air two phase mathematical model. Distribution of dynamic pressure, turbulent kinetic energy (k), turbulent dissipation rate (ε), free water surface and velocity field have been obtained. The simulated results were tested by physical model, which shows that the computed results are identical with that of the physical model.展开更多
Based on the ε - support vector regression, three modelling methods for the ship manoeuvring motion, i.e., the white-box modelling, the grey-box modelling and the black-box modelling, are investigated. The 10°/1...Based on the ε - support vector regression, three modelling methods for the ship manoeuvring motion, i.e., the white-box modelling, the grey-box modelling and the black-box modelling, are investigated. The 10°/10°, 20°/20° zigzag tests and the 35° turning circle manoeuvre are simulated. Part of the simulation data for the 20°/20° zigzag test are used to train the support vectors, and the trained support vector machine is used to predict the whole 20° / 20° zigzag test. Comparison between the simula- ted and predicted 20° / 20° zigzag test shows a good predictive ability of the three modelling methods. Then all mathematical models obtained by the modelling methods are used to predict the 10°/10° zigzag test and 35° turning circle manoeuvre, and the predicted results are compared with those of simulation tests to demonstrate the good generalization performance of the mathematical models. Finally, the modelling methods are analyzed and compared with each other in terms of the application conditions, the prediction accuracy and the computation speed. An appropriate modelling method can be chosen according to the intended use of the mathematical models and the available data for the system identification.展开更多
In order to study the cavitation damage in a side-wall when a sudden lateral enlargement and a vertical drop are imposed at the radial gate, a new arrangement-scheme is proposed, where the sudden lateral enlargement a...In order to study the cavitation damage in a side-wall when a sudden lateral enlargement and a vertical drop are imposed at the radial gate, a new arrangement-scheme is proposed, where the sudden lateral enlargement and the vertical drop can be imposed at the outlet of the gate chamber. The hydraulic characteristics along the side-wall are simulated by the detached eddy simulation and the Volume Of Fluid （VOF） method. The numerical results agree well with those of experiment. The experimental and numerical results show that the flow condition is smooth with only a weak water-wing appearing behind the lateral cavity, and the length of the lateral cavity becomes longer and is mainly affected by the size of the lateral enlargement and the zone of negative pressure after the water impacts the side-wall would disappear. The hydraulic characteristics of the new arrangement-scheme are beneficial to the prevention of the cavitation damage in the side-wall and the Detached Eddy Simulation （DES） with the VOF method can well predict the hydraulic characteristics after the new arrangement-scheme of the sudden lateral enlargement and the vertical drop.展开更多
Chronic stress is strongly associated with the occurrence and development of depression and cardiovascular disease.Stress can induce altered mitochondrial function and activation of apoptosis in the cardio-cerebral sy...Chronic stress is strongly associated with the occurrence and development of depression and cardiovascular disease.Stress can induce altered mitochondrial function and activation of apoptosis in the cardio-cerebral system.However,it is unknown whether the protein kinase C ε（PKCε）-aldehyde dehydrogenase 2（ALDH2） pathway is altered under chronic stress,and this study sought to address this question.A rat model of depression was established using a chronic unpredictable mild stress（CUMS） protocol.After experiencing CUMS for 4 weeks,the sucrose preference test and the forced swim test verified depressive-like behaviors.Enzyme linked immunosorbent assays showed that ALDH2 activity was decreased in the rat hippocampus and prefrontal cortex,but was not altered in the myocardium.Western blot assays demonstrated reduced levels of ALDH2 and PKCε,but increased levels of 4-hydroxy-2-nonenal（4 HNE） adducts.Caspase-3 expression did not obviously alter,but active forms of caspase-3 were increased in the hippocampus and prefrontal cortex.In the myocardium,expression of ALDH2,PKCε and 4 HNE adducts did not remarkably alter;while caspase-3 expression was reduced and the active forms of caspase-3 were upregulated.Pearson＇s correlation test demonstrated that expression of 4 HNE adducts was positively correlated with levels of the active forms of caspase-3 in the hippocampus and prefrontal cortex,but not in the myocardium.In conclusion,chronic stress can damage the PKCε-ALDH2 signaling pathway in the hippocampus and prefrontal cortex,but not in the myocardium.Moreover,4 HNE is associated with active forms of caspase-3 in the hippocampus and prefrontal cortex.展开更多
Thermodynamics of martensite transformation in low alloy TRIP steel was evaluated.It follows from the calculation that ε phase might be formed at above room temperature in the low Mn steel.Tested steel was therefore ...Thermodynamics of martensite transformation in low alloy TRIP steel was evaluated.It follows from the calculation that ε phase might be formed at above room temperature in the low Mn steel.Tested steel was therefore prepared according to the estimation result.High volume fraction of retained austenite(above 20%) containing 1.37%C was obtained in the steel after continuous annealing treatment.Tensile test showed that the ultimate strength of the steel was 1248 MPa,elongation rate 25%,the product of strength and elongation rate 31200 MPa%,reaching the grade of the third generation automobile steel.XRD detection indicated that after tensile test there existed ' martensite while TEM revealed that ε martensite also existed in the steel.Strengthening-toughening of the steel was thus raised due to the effect of transformation induced plasticity of two kinds of martensite.In addition,the phase stability of carbonitrates containing V was estimated and the complex micro-alloying effect was applied to the steel to control the size of austenite(about 1 μm) and enhance the stability of austenite.展开更多
Theoretically speaking, there are four kinds of possibilities to define the random conjugate space of a random locally convex module. The purpose of this paper is to prove that among the four kinds there are only two ...Theoretically speaking, there are four kinds of possibilities to define the random conjugate space of a random locally convex module. The purpose of this paper is to prove that among the four kinds there are only two which are universally suitable for the current development of the theory of random conjugate spaces. In this process, we also obtain a somewhat surprising and crucial result： if the base （Ω,F, P） of a random normed module is nonatomic then the random normed module is a totally disconnected topological space when it is endowed with the locally L0-convex topology.展开更多
The WA ε property and g NUC ε, g NUC Banach spaces are introduced. We prove that the WA ε property is equivalent to the WBS property and the g NUC ε (resp., g NUC) spaces are equivalent to the NUC ε ...The WA ε property and g NUC ε, g NUC Banach spaces are introduced. We prove that the WA ε property is equivalent to the WBS property and the g NUC ε (resp., g NUC) spaces are equivalent to the NUC ε (resp., NUC) spaces possessing the BS property. So we obtain a characterization of the NUC ε (resp., NUC) spaces possessing the BS property.展开更多
通过构建鸭乙肝病毒ε(Dε)的RNA文库并利用指数级富集的配体系统进化技术(SELEX)筛选的策略,获得与反转录酶(P蛋白)高度亲和的适配子(Aptamer),再通过体外引发实验和核酸酶切割方法测定全部适配子的RNA二级结构,以研究鸭乙型肝炎病毒(D...通过构建鸭乙肝病毒ε(Dε)的RNA文库并利用指数级富集的配体系统进化技术(SELEX)筛选的策略,获得与反转录酶(P蛋白)高度亲和的适配子(Aptamer),再通过体外引发实验和核酸酶切割方法测定全部适配子的RNA二级结构,以研究鸭乙型肝炎病毒(Duck Hepatitis B Virus,DHBV)中对启动P蛋白引发步骤至关重要的ε结构信息。本研究发现凡是支持P蛋白启动引发的高亲和力适配子中均包含完整的侧向突出结构;而一旦侧向突出被破坏,则适配子均不再支持P蛋白启动引发。本研究的结果表明Dε分子内部的一个完整侧向突出结构对于P蛋白启动引发是必不可少的。展开更多
The stress-strain-resistance relations of the Fe-Mn-Si alloys with different Si content have been investigated by measuring strain (ε) and resistance (△ R/R) upon tension synchronously. The results show that the str...The stress-strain-resistance relations of the Fe-Mn-Si alloys with different Si content have been investigated by measuring strain (ε) and resistance (△ R/R) upon tension synchronously. The results show that the strum induced γ→ε martensitic transfor- mation increases the strain sensitivity coeffcient of resistance (K) for the Fe-Mn-Si alloys in plastic region. There is a critical strum where dσ/dε becomes a constant value. Si increases the critical strum. A correlation between the critical strain and shape memory effect (SME) in the Fe-Mn-Si alloys is suggested.展开更多
Through in situ transmission electron microscopy observation on SUS304 metastable austenitic stainless steel during stretching at room temperature,it is found that e martensite plates were induced preferentially from ...Through in situ transmission electron microscopy observation on SUS304 metastable austenitic stainless steel during stretching at room temperature,it is found that e martensite plates were induced preferentially from the sites of dislocation pile-ups.With increasing deformation,some of ε thin martensite platelets disappear and reversibly transform toγ austenite without heating treatment,which is different from the previous result that ε martensite can entirely transform toα＇martensite.Then,some of deformation twins appear and grow along the vertical direction of ε martensite due to（111）_γ⊥（1010）_ε.Moreover,it is directly observed that multiple transformation mechanisms via γ→ε→γ,γ→ε,γ→α′,γ→ε→α′,γ→ deformation twins →α′ can co-exist.展开更多
文摘A new non-hydrostatic numerical model with the three-dimensional Navier-Stokes equations on structured grids was constructed and discussed. The algorithm is based upon a staggered finite difference Crank-Nicholson scheme on a Cartesian grid. The eddy viscosity coefficient was calculated by the efficient k-ε turbulence model. A new surface-layer non-hydrostatic treatment and a local cell bottom treatment were introduced so that the three-dimensional model is fully non-hydrostatic and is free of any hydrostatic assumption. The developed model is second-order accuracy in both time and space when semi-implicit coefficient is set to 0.5. The validity of the present solution algorithm was demonstrated from its application to the three-dimension channel flow and the wave propagation over a submerged bar problems.
文摘Two independent versions of the RNG based k ε turbulence model in conjunction with the law of the wall have been applied to the numerical simulation of an axisymmetric turbulent impinging jet flow field. The two model predictions are compared with those of the standard k ε model and with the experimental data measured by LDV (Laser Doppler Velocimetry). It shows that the original version of the RNG k ε model with the choice of C ε1 =1.063 can not yield good results, among them the predicted turbulent kinetic energy profiles in the vicinity of the stagnation region are even worse than those predicted by the standard k ε model. However, the new version of RNG k ε model behaves well. This is mainly due to the corrections to the constants C ε1 and C ε2 along with a modification of the production term to account for non equilibrium strain rates in the flow.
基金The author is partially supported by the National Science Foundation of U.S.,Grant DMS96-22996
文摘This paper consists of three main parts.One of them is to develop local and global Sobolev interpolation inequalities of any higher order for the nonisotropic Sobolev spaces on stratified nilpotent Lie groups.Despite the extensive research after Jerison’s work[3]on Poincaré-type inequalities for Hrmander’s vector fields over the years,our results given here even in the nonweighted case appear to be new.Such interpolation inequalities have crucial applications to subelliptic or parabolic PDE’s involving vector fields.The main tools to prove such inequalities are approximating the Sobolev func- tions by polynomials associated with the left invariant vector fields on G.Some very useful properties for polynomials associated with the functions are given here and they appear to have independent interests in their own rights.Finding the existence of such polynomials is the second main part of this paper.Main results of these two parts have been announced in the author’s paper in Mathematical Research Letters[38]. The third main part of this paper contains extension theorems on anisotropic Sobolev spaces on stratified groups and their applications to proving Sobolev interpolation inequalities on(εδ)domains. Some results of weighted Sobolev spaces are also given here.We construct a linear extension operator which is bounded on different Sobolev spaces simultaneously.In particular,we are able to construct a bounded linear extension operator such that the derivatives of the extended function can be controlled by the same order of derivatives of the given Sobolev functions.Theorems are stated and proved for weighted anisotropic Sobolev spaces on stratified groups.
文摘Flood discharge over top outlet of dam is simulated by 2 dimension water air two phase mathematical model. Distribution of dynamic pressure, turbulent kinetic energy (k), turbulent dissipation rate (ε), free water surface and velocity field have been obtained. The simulated results were tested by physical model, which shows that the computed results are identical with that of the physical model.
基金Project supported by the National Natural Science Foundation of China(Grant No.51279106)the Special Research Fund for the Doctoral Program of Higher Education of China(Grant No.20110073110009)
文摘Based on the ε - support vector regression, three modelling methods for the ship manoeuvring motion, i.e., the white-box modelling, the grey-box modelling and the black-box modelling, are investigated. The 10°/10°, 20°/20° zigzag tests and the 35° turning circle manoeuvre are simulated. Part of the simulation data for the 20°/20° zigzag test are used to train the support vectors, and the trained support vector machine is used to predict the whole 20° / 20° zigzag test. Comparison between the simula- ted and predicted 20° / 20° zigzag test shows a good predictive ability of the three modelling methods. Then all mathematical models obtained by the modelling methods are used to predict the 10°/10° zigzag test and 35° turning circle manoeuvre, and the predicted results are compared with those of simulation tests to demonstrate the good generalization performance of the mathematical models. Finally, the modelling methods are analyzed and compared with each other in terms of the application conditions, the prediction accuracy and the computation speed. An appropriate modelling method can be chosen according to the intended use of the mathematical models and the available data for the system identification.
基金supported by the Natural National Science Foundation of China (Grant No. 50779041)the Ph. D. Program Foundation of Ministry of Education of China (Grant No.20060610039)
文摘In order to study the cavitation damage in a side-wall when a sudden lateral enlargement and a vertical drop are imposed at the radial gate, a new arrangement-scheme is proposed, where the sudden lateral enlargement and the vertical drop can be imposed at the outlet of the gate chamber. The hydraulic characteristics along the side-wall are simulated by the detached eddy simulation and the Volume Of Fluid （VOF） method. The numerical results agree well with those of experiment. The experimental and numerical results show that the flow condition is smooth with only a weak water-wing appearing behind the lateral cavity, and the length of the lateral cavity becomes longer and is mainly affected by the size of the lateral enlargement and the zone of negative pressure after the water impacts the side-wall would disappear. The hydraulic characteristics of the new arrangement-scheme are beneficial to the prevention of the cavitation damage in the side-wall and the Detached Eddy Simulation （DES） with the VOF method can well predict the hydraulic characteristics after the new arrangement-scheme of the sudden lateral enlargement and the vertical drop.
基金supported by the Medical Research Fund of Guangdong Province of China,No.B2014449a grant from the Science and Technology Project of Zhongshan City of China,No.2014A1FC137
文摘Chronic stress is strongly associated with the occurrence and development of depression and cardiovascular disease.Stress can induce altered mitochondrial function and activation of apoptosis in the cardio-cerebral system.However,it is unknown whether the protein kinase C ε（PKCε）-aldehyde dehydrogenase 2（ALDH2） pathway is altered under chronic stress,and this study sought to address this question.A rat model of depression was established using a chronic unpredictable mild stress（CUMS） protocol.After experiencing CUMS for 4 weeks,the sucrose preference test and the forced swim test verified depressive-like behaviors.Enzyme linked immunosorbent assays showed that ALDH2 activity was decreased in the rat hippocampus and prefrontal cortex,but was not altered in the myocardium.Western blot assays demonstrated reduced levels of ALDH2 and PKCε,but increased levels of 4-hydroxy-2-nonenal（4 HNE） adducts.Caspase-3 expression did not obviously alter,but active forms of caspase-3 were increased in the hippocampus and prefrontal cortex.In the myocardium,expression of ALDH2,PKCε and 4 HNE adducts did not remarkably alter;while caspase-3 expression was reduced and the active forms of caspase-3 were upregulated.Pearson＇s correlation test demonstrated that expression of 4 HNE adducts was positively correlated with levels of the active forms of caspase-3 in the hippocampus and prefrontal cortex,but not in the myocardium.In conclusion,chronic stress can damage the PKCε-ALDH2 signaling pathway in the hippocampus and prefrontal cortex,but not in the myocardium.Moreover,4 HNE is associated with active forms of caspase-3 in the hippocampus and prefrontal cortex.
基金supported by National Key Basic Research and Development Project of China "973 Program" (Grant No. 2010CB-630802)the National Natural Sciences Foundation of China (GrantNos. 50934011 and 50971137)
文摘Thermodynamics of martensite transformation in low alloy TRIP steel was evaluated.It follows from the calculation that ε phase might be formed at above room temperature in the low Mn steel.Tested steel was therefore prepared according to the estimation result.High volume fraction of retained austenite(above 20%) containing 1.37%C was obtained in the steel after continuous annealing treatment.Tensile test showed that the ultimate strength of the steel was 1248 MPa,elongation rate 25%,the product of strength and elongation rate 31200 MPa%,reaching the grade of the third generation automobile steel.XRD detection indicated that after tensile test there existed ' martensite while TEM revealed that ε martensite also existed in the steel.Strengthening-toughening of the steel was thus raised due to the effect of transformation induced plasticity of two kinds of martensite.In addition,the phase stability of carbonitrates containing V was estimated and the complex micro-alloying effect was applied to the steel to control the size of austenite(about 1 μm) and enhance the stability of austenite.
基金Supported by National Natural Science Foundation of China(Grant No.10871016)
文摘Theoretically speaking, there are four kinds of possibilities to define the random conjugate space of a random locally convex module. The purpose of this paper is to prove that among the four kinds there are only two which are universally suitable for the current development of the theory of random conjugate spaces. In this process, we also obtain a somewhat surprising and crucial result： if the base （Ω,F, P） of a random normed module is nonatomic then the random normed module is a totally disconnected topological space when it is endowed with the locally L0-convex topology.
文摘The WA ε property and g NUC ε, g NUC Banach spaces are introduced. We prove that the WA ε property is equivalent to the WBS property and the g NUC ε (resp., g NUC) spaces are equivalent to the NUC ε (resp., NUC) spaces possessing the BS property. So we obtain a characterization of the NUC ε (resp., NUC) spaces possessing the BS property.
文摘通过构建鸭乙肝病毒ε(Dε)的RNA文库并利用指数级富集的配体系统进化技术(SELEX)筛选的策略,获得与反转录酶(P蛋白)高度亲和的适配子(Aptamer),再通过体外引发实验和核酸酶切割方法测定全部适配子的RNA二级结构,以研究鸭乙型肝炎病毒(Duck Hepatitis B Virus,DHBV)中对启动P蛋白引发步骤至关重要的ε结构信息。本研究发现凡是支持P蛋白启动引发的高亲和力适配子中均包含完整的侧向突出结构;而一旦侧向突出被破坏,则适配子均不再支持P蛋白启动引发。本研究的结果表明Dε分子内部的一个完整侧向突出结构对于P蛋白启动引发是必不可少的。
文摘The stress-strain-resistance relations of the Fe-Mn-Si alloys with different Si content have been investigated by measuring strain (ε) and resistance (△ R/R) upon tension synchronously. The results show that the strum induced γ→ε martensitic transfor- mation increases the strain sensitivity coeffcient of resistance (K) for the Fe-Mn-Si alloys in plastic region. There is a critical strum where dσ/dε becomes a constant value. Si increases the critical strum. A correlation between the critical strain and shape memory effect (SME) in the Fe-Mn-Si alloys is suggested.
基金financially supported by the National Natural Science Foundation of China (No. 51105248)
文摘Through in situ transmission electron microscopy observation on SUS304 metastable austenitic stainless steel during stretching at room temperature,it is found that e martensite plates were induced preferentially from the sites of dislocation pile-ups.With increasing deformation,some of ε thin martensite platelets disappear and reversibly transform toγ austenite without heating treatment,which is different from the previous result that ε martensite can entirely transform toα＇martensite.Then,some of deformation twins appear and grow along the vertical direction of ε martensite due to（111）_γ⊥（1010）_ε.Moreover,it is directly observed that multiple transformation mechanisms via γ→ε→γ,γ→ε,γ→α′,γ→ε→α′,γ→ deformation twins →α′ can co-exist.
