This paper introduces a grey classifica- tion method forevaluating the stability of dangerous rock- block masses according tothe Grey System Theory. This method is applied to the stability ofthe V~# dangerous rock- bl...This paper introduces a grey classifica- tion method forevaluating the stability of dangerous rock- block masses according tothe Grey System Theory. This method is applied to the stability ofthe V~# dangerous rock- block masses of Qingjiang water conservancyproject, and better results are abtained. The method which isadvanced in the article is very single and practical, and it can meetall kinds of project's demands.展开更多
We examine the impact of electromagnetic field on the stability of compact stars corresponding to embedded class one metric using the concept of cracking. For this purpose, we develop the generalized hydrostatic equi-...We examine the impact of electromagnetic field on the stability of compact stars corresponding to embedded class one metric using the concept of cracking. For this purpose, we develop the generalized hydrostatic equi- librium equation for charged perfect fluid distribution of compact stars and perturb it by means of local density perturbation scheme to check the stability of inner matter configuration. We investigate the cracking of Her X-I, PSR 1937+21, PSR J 1614-2230, PSR J 0348+0432 and B.X J 1856-37. We conclude that PSR J 0348+0432 and RX J 1856-37 exhibit cracking when charge is introduced on these astrophysical objects.展开更多
Based on the hydrodynamic stability theory of distorted laminar flow and the kind of distortion profiles on the mean velocity in parallel shear flow given in paper [1], this paper investigates the linear stability beh...Based on the hydrodynamic stability theory of distorted laminar flow and the kind of distortion profiles on the mean velocity in parallel shear flow given in paper [1], this paper investigates the linear stability behaviour of parallel shear flow, presents unstable results of plane Couette flow and pipe Poiseuille flow to two-dimensional or axisymmetric disturbances for the first time, and obtains neutral curves of these two motions under certain definition.展开更多
A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constant...A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constants of complexes at 25℃ with I=0.10 mol dm^(-3)(KNO_3).The com- puter programs SUPERQUAD were applied for data treatment with satisfactory results.展开更多
We carry out first-principles calculations of Ru(0001) films up to 30 monolayers (MLs) to study the quantum size effect (Q, SE) of Ru films for two cases: the freestanding Ru films and Ru films on Pt(111) sub...We carry out first-principles calculations of Ru(0001) films up to 30 monolayers (MLs) to study the quantum size effect (Q, SE) of Ru films for two cases: the freestanding Ru films and Ru films on Pt(111) substrates. Our studies show that the properties of these films (surface energy, work-function, charge density decay length in a vacuum and chemical reactivity) exhibit pronounced oscillatory behavior as a function of the film thickness, with an oscillation period of about four MLs for both cases due to the relationship of the match between the Fermi wave vector and the film thickness. Due to the localization of d-electron of Ru films, these quantum oscillations almost disappear when the thickness of the film is more than -20 ML for the free standing Ru films, while for the Ru films on Pt substrates the oscillations disappear quickly when the thickness of the film is beyond -13 ML. Our results reveal that the stability and reactivity of the Ru films could be tailored through Q, SE and the Ru bilayer grown on Pt substrates observed in the experiment is also related to the effect.展开更多
This paper suggests a hydrodynamic stability theory of distorted laminar flow, and presents a kind of distortion profile of mean velocity in parallel shear flow. With such distortion profiles, the new theory can be us...This paper suggests a hydrodynamic stability theory of distorted laminar flow, and presents a kind of distortion profile of mean velocity in parallel shear flow. With such distortion profiles, the new theory can be used to investigate the stability behaviour of parallel shear flow, and thus suggests a new possible approach to instability.展开更多
Based on the hydrodynamic stability theory of distorted laminar flow and the kind of distortion profiles on the mean velocity in parallel shear flow given in paper [1], this paper investigates the nonlinear stability ...Based on the hydrodynamic stability theory of distorted laminar flow and the kind of distortion profiles on the mean velocity in parallel shear flow given in paper [1], this paper investigates the nonlinear stability behaviour of parallel shear flow, carries on stability calculation taking account of the perturbations of background turbulence noise under certain assumption, and obtains some results in accordance qualitatively with those of experiment for plane Poiseuille flow and pipe Poiseuille flow.展开更多
The stabilities of the complexes of three pyridine-like ligands with M(II)(ATP)^(2-) and M(II)(M=Ni,Co)were studied by spectrophotometry and by comparing the stability constants of the ternary complexes with these of ...The stabilities of the complexes of three pyridine-like ligands with M(II)(ATP)^(2-) and M(II)(M=Ni,Co)were studied by spectrophotometry and by comparing the stability constants of the ternary complexes with these of the binary complexes.A stacking interaction between the pyridine ring and the purine ring of ATP is indicated.The general existence of the stacking interaction encourages us to interpret the antitumor mechanism of a new class of antitumor drugs.展开更多
The stability of beta zeollie in acid solution and the effect of acid treatment on the polymorphs in beta zeolite were studied. This zeolite is easily dealuminated by HCI treatment but its framework highly resistent t...The stability of beta zeollie in acid solution and the effect of acid treatment on the polymorphs in beta zeolite were studied. This zeolite is easily dealuminated by HCI treatment but its framework highly resistent to acidity.In β zeolite, polymorph A is less stable than polymorph B.The chirality of β zeolite can be modified by the method of acid treatment.展开更多
Using a two-dimensional semi-geostrophic model. the stability of fronts near shelf break (shelfbreak font, western boundary current front) and its mechanism are studied. We find that the stability of the front is rela...Using a two-dimensional semi-geostrophic model. the stability of fronts near shelf break (shelfbreak font, western boundary current front) and its mechanism are studied. We find that the stability of the front is related to the frontal structure. In general, the increase of the lower layer depth lowers the unstable growth rate (a1). (1) The shelfbreak front is baroclinically unstable and ai increases with the increase of the bottom slope, different from the conclusion of Flagg and Beardsley (1978). (2) A western boundary current front with uniform vorticity in the upper layer is barotropically unstable, due to the strong horizontal shear of the mean current. The unstable growth rate of this front for a realistic topography is only one seventh of that of the flat bottom case. (3) For a western boundary current front with hyperbolic tangent structure, we find its wave propagation speed to be about 0. 5 m/s, in agreement with the observed values. The front is baroclinically unstable. (4)The unstable growth rate of a domed structure front and its wave speed do not seem to be related to its wavelength. The front is baroclinically unstable.展开更多
In this paper we make a close study of the finite analytic method by means of the maximum principles in differential equations and give the proof of the stability and convergence of the finite analytic method.
As one of the bases of gradient-based optimization algorithms, sensitivity analysis is usually required to calculate the derivatives of the system response with respect to the machining parameters. The most widely use...As one of the bases of gradient-based optimization algorithms, sensitivity analysis is usually required to calculate the derivatives of the system response with respect to the machining parameters. The most widely used approaches for sensitivity analysis are based on time-consuming numerical methods, such as finite difference methods. This paper presents a semi-analytical method for calculation of the sensitivity of the stability boundary in milling. After transforming the delay-differential equation with time-periodic coefficients governing the dynamic milling process into the integral form, the Floquet transition matrix is constructed by using the numerical integration method. Then, the analytical expressions of derivatives of the Floquet transition matrix with respect to the machining parameters are obtained. Thereafter, the classical analytical expression of the sensitivity of matrix eigenvalues is employed to calculate the sensitivity of the stability lobe diagram. The two-degree-of-freedom milling example illustrates the accuracy and efficiency of the proposed method. Compared with the existing methods, the unique merit of the proposed method is that it can be used for analytically computing the sensitivity of the stability boundary in milling, without employing any finite difference methods. Therefore, the high accuracy and high efficiency are both achieved. The proposed method can serve as an effective tool for machining parameter optimization and uncertainty analysis in high-speed milling.展开更多
This paper deals with the stability analysis of θ-methods for the numericalsolution of delny dmerential equations (DDEs). We focus on the behavioux of suchmethods in the solution of the linear test equation y'(t)...This paper deals with the stability analysis of θ-methods for the numericalsolution of delny dmerential equations (DDEs). We focus on the behavioux of suchmethods in the solution of the linear test equation y'(t) = a(t)y(t) + b(t)y(t - T),where T > o, a(t) and b(t) are functions from R to C. It is proved that the linearθ-method and the one-leg θ-method are TGP-stable if and only if θ = 1.展开更多
This paper discusses the stability structure and the bifurcation of phase path characteristics of synoptic scale system.The analytic results show that the catastrophe of the synoptic scale disturbance may be caused by...This paper discusses the stability structure and the bifurcation of phase path characteristics of synoptic scale system.The analytic results show that the catastrophe of the synoptic scale disturbance may be caused by the nonlinear effects of barotropic and baroclinic instability and advection of ambient large-scale flow.Also, foregoing nonlinear effects on the speed of development and decay of the system are presented in the processes deviating from or approaching to equilibrium state.It has been found that there is a resonance phenomenon between the time-oscillation of heat source and the atmospheric disturbance.展开更多
In this paper, the author considered the stability of zero solution of linear RDDEx(t) + p_1(t)x(t) + q_1(t)x(t)+p_2(t)x(t-r(t))+q_2(t)x(t-r(t))=0,(1)x(t) +p_1(t)x(t)+q_1(t)x(t)+q_2(t)x(t-r(t))=0 (2)using Liapunov-Raz...In this paper, the author considered the stability of zero solution of linear RDDEx(t) + p_1(t)x(t) + q_1(t)x(t)+p_2(t)x(t-r(t))+q_2(t)x(t-r(t))=0,(1)x(t) +p_1(t)x(t)+q_1(t)x(t)+q_2(t)x(t-r(t))=0 (2)using Liapunov-Razumikhin functional and transformations and obtained some sufficient condi-tions for the stability of Eqs.(1) and (2). These results are suitable both for bounded p_i(t), q_i(t)and r(t).i =1, 2.展开更多
The acid dissociation constants of N-carboxymethyl-N-(p-hydroxy phenyl carbamoyl- methyl)-2,3-dihydroxy-5-carbomethoxy benzylamine(CHDCB) and the stability constants of its 1:1 complexes with alkaline earth, Cd(Ⅱ), ...The acid dissociation constants of N-carboxymethyl-N-(p-hydroxy phenyl carbamoyl- methyl)-2,3-dihydroxy-5-carbomethoxy benzylamine(CHDCB) and the stability constants of its 1:1 complexes with alkaline earth, Cd(Ⅱ), Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Fe(Ⅲ),Th(Ⅳ)and U(Ⅵ)ions have been determined at 25.0±0.1℃ and at an ionic strength of 0.1(KNO_3)by pH titration method. The probable coordination sites have also been discussed.展开更多
The stability constants of the binary complexes of type PbB, PbB_2, and the mixed ligand complexes of type PbAB have been studied by potentiometric pH titration technique at ionic strength I=0.10 (KNO_3) and at temper...The stability constants of the binary complexes of type PbB, PbB_2, and the mixed ligand complexes of type PbAB have been studied by potentiometric pH titration technique at ionic strength I=0.10 (KNO_3) and at temperature 15, 25, 35 and 45℃ respectively, where A=2,2'-bipyridyl (bipy) or 1, 10-phenanthroline (phen); B=malonate (mal), succinate (suc), or anthranilate (anth). The equalibrium constants logK,~1 G, H, and S of the reaction PbA+PbB=PbAB+Pb^2+ have been calculated. The results show that the discriminating effects^2 between the primary ligand (bipy or phen) and the secondary ligand (real, suc or anth) in those non-transition metal mixed ligand complexes are also evident, and as a measurement of this effect, H is more appropriate than logK. The possible reasons which lead to these results have been discussed.展开更多
文摘This paper introduces a grey classifica- tion method forevaluating the stability of dangerous rock- block masses according tothe Grey System Theory. This method is applied to the stability ofthe V~# dangerous rock- block masses of Qingjiang water conservancyproject, and better results are abtained. The method which isadvanced in the article is very single and practical, and it can meetall kinds of project's demands.
文摘We examine the impact of electromagnetic field on the stability of compact stars corresponding to embedded class one metric using the concept of cracking. For this purpose, we develop the generalized hydrostatic equi- librium equation for charged perfect fluid distribution of compact stars and perturb it by means of local density perturbation scheme to check the stability of inner matter configuration. We investigate the cracking of Her X-I, PSR 1937+21, PSR J 1614-2230, PSR J 0348+0432 and B.X J 1856-37. We conclude that PSR J 0348+0432 and RX J 1856-37 exhibit cracking when charge is introduced on these astrophysical objects.
文摘Based on the hydrodynamic stability theory of distorted laminar flow and the kind of distortion profiles on the mean velocity in parallel shear flow given in paper [1], this paper investigates the linear stability behaviour of parallel shear flow, presents unstable results of plane Couette flow and pipe Poiseuille flow to two-dimensional or axisymmetric disturbances for the first time, and obtains neutral curves of these two motions under certain definition.
文摘A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constants of complexes at 25℃ with I=0.10 mol dm^(-3)(KNO_3).The com- puter programs SUPERQUAD were applied for data treatment with satisfactory results.
文摘We carry out first-principles calculations of Ru(0001) films up to 30 monolayers (MLs) to study the quantum size effect (Q, SE) of Ru films for two cases: the freestanding Ru films and Ru films on Pt(111) substrates. Our studies show that the properties of these films (surface energy, work-function, charge density decay length in a vacuum and chemical reactivity) exhibit pronounced oscillatory behavior as a function of the film thickness, with an oscillation period of about four MLs for both cases due to the relationship of the match between the Fermi wave vector and the film thickness. Due to the localization of d-electron of Ru films, these quantum oscillations almost disappear when the thickness of the film is more than -20 ML for the free standing Ru films, while for the Ru films on Pt substrates the oscillations disappear quickly when the thickness of the film is beyond -13 ML. Our results reveal that the stability and reactivity of the Ru films could be tailored through Q, SE and the Ru bilayer grown on Pt substrates observed in the experiment is also related to the effect.
基金Project Supported by National Natural Science Foundation of China
文摘This paper suggests a hydrodynamic stability theory of distorted laminar flow, and presents a kind of distortion profile of mean velocity in parallel shear flow. With such distortion profiles, the new theory can be used to investigate the stability behaviour of parallel shear flow, and thus suggests a new possible approach to instability.
文摘Based on the hydrodynamic stability theory of distorted laminar flow and the kind of distortion profiles on the mean velocity in parallel shear flow given in paper [1], this paper investigates the nonlinear stability behaviour of parallel shear flow, carries on stability calculation taking account of the perturbations of background turbulence noise under certain assumption, and obtains some results in accordance qualitatively with those of experiment for plane Poiseuille flow and pipe Poiseuille flow.
基金Supported by the National Natural Science Foundation of Chinathe Doctoral Program Foundation of Institution of High Education the Research Foundation of State Key Laboratory of Coordination Chemistry,Nanjing University.
文摘The stabilities of the complexes of three pyridine-like ligands with M(II)(ATP)^(2-) and M(II)(M=Ni,Co)were studied by spectrophotometry and by comparing the stability constants of the ternary complexes with these of the binary complexes.A stacking interaction between the pyridine ring and the purine ring of ATP is indicated.The general existence of the stacking interaction encourages us to interpret the antitumor mechanism of a new class of antitumor drugs.
文摘The stability of beta zeollie in acid solution and the effect of acid treatment on the polymorphs in beta zeolite were studied. This zeolite is easily dealuminated by HCI treatment but its framework highly resistent to acidity.In β zeolite, polymorph A is less stable than polymorph B.The chirality of β zeolite can be modified by the method of acid treatment.
文摘Using a two-dimensional semi-geostrophic model. the stability of fronts near shelf break (shelfbreak font, western boundary current front) and its mechanism are studied. We find that the stability of the front is related to the frontal structure. In general, the increase of the lower layer depth lowers the unstable growth rate (a1). (1) The shelfbreak front is baroclinically unstable and ai increases with the increase of the bottom slope, different from the conclusion of Flagg and Beardsley (1978). (2) A western boundary current front with uniform vorticity in the upper layer is barotropically unstable, due to the strong horizontal shear of the mean current. The unstable growth rate of this front for a realistic topography is only one seventh of that of the flat bottom case. (3) For a western boundary current front with hyperbolic tangent structure, we find its wave propagation speed to be about 0. 5 m/s, in agreement with the observed values. The front is baroclinically unstable. (4)The unstable growth rate of a domed structure front and its wave speed do not seem to be related to its wavelength. The front is baroclinically unstable.
文摘In this paper we make a close study of the finite analytic method by means of the maximum principles in differential equations and give the proof of the stability and convergence of the finite analytic method.
基金supported by National Key Basic Research Program (973 Program, Grant No. 2011CB706804)National Natural Science Foundation of China (Grant No. 50805093)Science & Technology Commission of Shanghai Municipality, China (Grant No. 09QH1401500)
文摘As one of the bases of gradient-based optimization algorithms, sensitivity analysis is usually required to calculate the derivatives of the system response with respect to the machining parameters. The most widely used approaches for sensitivity analysis are based on time-consuming numerical methods, such as finite difference methods. This paper presents a semi-analytical method for calculation of the sensitivity of the stability boundary in milling. After transforming the delay-differential equation with time-periodic coefficients governing the dynamic milling process into the integral form, the Floquet transition matrix is constructed by using the numerical integration method. Then, the analytical expressions of derivatives of the Floquet transition matrix with respect to the machining parameters are obtained. Thereafter, the classical analytical expression of the sensitivity of matrix eigenvalues is employed to calculate the sensitivity of the stability lobe diagram. The two-degree-of-freedom milling example illustrates the accuracy and efficiency of the proposed method. Compared with the existing methods, the unique merit of the proposed method is that it can be used for analytically computing the sensitivity of the stability boundary in milling, without employing any finite difference methods. Therefore, the high accuracy and high efficiency are both achieved. The proposed method can serve as an effective tool for machining parameter optimization and uncertainty analysis in high-speed milling.
文摘This paper deals with the stability analysis of θ-methods for the numericalsolution of delny dmerential equations (DDEs). We focus on the behavioux of suchmethods in the solution of the linear test equation y'(t) = a(t)y(t) + b(t)y(t - T),where T > o, a(t) and b(t) are functions from R to C. It is proved that the linearθ-method and the one-leg θ-method are TGP-stable if and only if θ = 1.
文摘This paper discusses the stability structure and the bifurcation of phase path characteristics of synoptic scale system.The analytic results show that the catastrophe of the synoptic scale disturbance may be caused by the nonlinear effects of barotropic and baroclinic instability and advection of ambient large-scale flow.Also, foregoing nonlinear effects on the speed of development and decay of the system are presented in the processes deviating from or approaching to equilibrium state.It has been found that there is a resonance phenomenon between the time-oscillation of heat source and the atmospheric disturbance.
文摘In this paper, the author considered the stability of zero solution of linear RDDEx(t) + p_1(t)x(t) + q_1(t)x(t)+p_2(t)x(t-r(t))+q_2(t)x(t-r(t))=0,(1)x(t) +p_1(t)x(t)+q_1(t)x(t)+q_2(t)x(t-r(t))=0 (2)using Liapunov-Razumikhin functional and transformations and obtained some sufficient condi-tions for the stability of Eqs.(1) and (2). These results are suitable both for bounded p_i(t), q_i(t)and r(t).i =1, 2.
文摘The acid dissociation constants of N-carboxymethyl-N-(p-hydroxy phenyl carbamoyl- methyl)-2,3-dihydroxy-5-carbomethoxy benzylamine(CHDCB) and the stability constants of its 1:1 complexes with alkaline earth, Cd(Ⅱ), Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Fe(Ⅲ),Th(Ⅳ)and U(Ⅵ)ions have been determined at 25.0±0.1℃ and at an ionic strength of 0.1(KNO_3)by pH titration method. The probable coordination sites have also been discussed.
文摘The stability constants of the binary complexes of type PbB, PbB_2, and the mixed ligand complexes of type PbAB have been studied by potentiometric pH titration technique at ionic strength I=0.10 (KNO_3) and at temperature 15, 25, 35 and 45℃ respectively, where A=2,2'-bipyridyl (bipy) or 1, 10-phenanthroline (phen); B=malonate (mal), succinate (suc), or anthranilate (anth). The equalibrium constants logK,~1 G, H, and S of the reaction PbA+PbB=PbAB+Pb^2+ have been calculated. The results show that the discriminating effects^2 between the primary ligand (bipy or phen) and the secondary ligand (real, suc or anth) in those non-transition metal mixed ligand complexes are also evident, and as a measurement of this effect, H is more appropriate than logK. The possible reasons which lead to these results have been discussed.