An integral constitutive equation and a set of material functions for describing the strain history of polymer melts were formulated in terms of the Cauchy-Green and Finger tensors. A simple memory function and the de...An integral constitutive equation and a set of material functions for describing the strain history of polymer melts were formulated in terms of the Cauchy-Green and Finger tensors. A simple memory function and the dependence of ηo and τt on M3.4 were derived from the theory of non-linear viscoelasticity with constraints of entanglements for polymer melts and substituted into the Oldroye-Walters-Fredickson constitutive equation. An integral constitutive equation for polymer melts was consequently obtained. Some material functions of the constitutive equation related to certain 'test flow' are examined as follows : (1) simple steady shear flow; (2) steady elongation flow; (3) small-amplitude oscillatory shear flow; (4) stress growth upon the inception of steady shear elongation flow; (5) stress relaxation (modulus and compllance). These theoretical relations for simple steady shear flow were compared with experimental data from our laboratory and references for various polymer melts and concentrated solutions. A good agreement between the theory and experiment was achieved.展开更多
Results of analytical studies of the physical properties of the function and number of empirical macrohardness based on the standard experimental force diagram of kinetic macroindentation by a sphere.An analytical com...Results of analytical studies of the physical properties of the function and number of empirical macrohardness based on the standard experimental force diagram of kinetic macroindentation by a sphere.An analytical comparison method and a criterion for the similarity of the physical and empirical macrohardness of a material are proposed.The physical properties of the hardness measurement process using the Calvert-Johnson method are shown.The physical reasons for the size effect when measuring macrohardness are considered.The universal physical unit and standard of macrohardness of kinetic macroindentation by a sphere is substantiated.展开更多
We find that a conserved mutation residue Glu to residue Asp (E303D), which both have the same polar and charged properties, makes Kit2.1 protein lose its function. To understand the mechanism, we identify three int...We find that a conserved mutation residue Glu to residue Asp (E303D), which both have the same polar and charged properties, makes Kit2.1 protein lose its function. To understand the mechanism, we identify three interactions which control the conformation change and maintain the function of the Kit2.1 protein by combining homology modeling and molecular dynamics with targeted molecular dynamics. We find that the E303D mutation weakens these interactions and results in the loss of the related function. Our data indicate that not only the amino residues but also the interactions determine the function of proteins.展开更多
This paper discusses the numbers of jump layers of boundary value problems in quasilinear differential equations. In addition, the paper gives several examples to explain why the original equation must be rediscussed ...This paper discusses the numbers of jump layers of boundary value problems in quasilinear differential equations. In addition, the paper gives several examples to explain why the original equation must be rediscussed when the determinate function in reference [1 ] is a/ways equal to zero.展开更多
The work presented in this paper is a part of the TLP project undertaken in CSSRC(Chins Ship Scientific Research Center). Model tests were performed in seakeeping basin at CSSRC. Wave envelopes are calculated from tim...The work presented in this paper is a part of the TLP project undertaken in CSSRC(Chins Ship Scientific Research Center). Model tests were performed in seakeeping basin at CSSRC. Wave envelopes are calculated from time records of the irregular waves using Hilbert transform.Time histories of surge motions of the model were recorded in long-crested irregular head seas.The low-frequency response was separated from the time history using a low pass filter.The quadratic transfer functions were obtained from ratio of the cross-spectrum(between the low-frequency surge response and the square of the wave envelope)and the auto-spectrum of the square of the wave envelope.展开更多
This paper introduces a new method to solve Liapunov stability problems for time invariant nonlinear systems—the normal determinative function method. The topic is split into six parts: review of the construction of...This paper introduces a new method to solve Liapunov stability problems for time invariant nonlinear systems—the normal determinative function method. The topic is split into six parts: review of the construction of a V(x) function, the modified Liapunov theorem form while the derivative of V(x) is definite, polynomial features of the analytic system’s normal determinative function V(x), judgment of definitiveness for a polynomial, coefficient direct solution method and the stabilty judgment of critical nonlinear systems, and future research.展开更多
文摘An integral constitutive equation and a set of material functions for describing the strain history of polymer melts were formulated in terms of the Cauchy-Green and Finger tensors. A simple memory function and the dependence of ηo and τt on M3.4 were derived from the theory of non-linear viscoelasticity with constraints of entanglements for polymer melts and substituted into the Oldroye-Walters-Fredickson constitutive equation. An integral constitutive equation for polymer melts was consequently obtained. Some material functions of the constitutive equation related to certain 'test flow' are examined as follows : (1) simple steady shear flow; (2) steady elongation flow; (3) small-amplitude oscillatory shear flow; (4) stress growth upon the inception of steady shear elongation flow; (5) stress relaxation (modulus and compllance). These theoretical relations for simple steady shear flow were compared with experimental data from our laboratory and references for various polymer melts and concentrated solutions. A good agreement between the theory and experiment was achieved.
文摘Results of analytical studies of the physical properties of the function and number of empirical macrohardness based on the standard experimental force diagram of kinetic macroindentation by a sphere.An analytical comparison method and a criterion for the similarity of the physical and empirical macrohardness of a material are proposed.The physical properties of the hardness measurement process using the Calvert-Johnson method are shown.The physical reasons for the size effect when measuring macrohardness are considered.The universal physical unit and standard of macrohardness of kinetic macroindentation by a sphere is substantiated.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11247010,11175055,11475053 and 11347017the Natural Science Foundation of Hebei Province under Grant Nos C2012202079 and C201400305
文摘We find that a conserved mutation residue Glu to residue Asp (E303D), which both have the same polar and charged properties, makes Kit2.1 protein lose its function. To understand the mechanism, we identify three interactions which control the conformation change and maintain the function of the Kit2.1 protein by combining homology modeling and molecular dynamics with targeted molecular dynamics. We find that the E303D mutation weakens these interactions and results in the loss of the related function. Our data indicate that not only the amino residues but also the interactions determine the function of proteins.
文摘This paper discusses the numbers of jump layers of boundary value problems in quasilinear differential equations. In addition, the paper gives several examples to explain why the original equation must be rediscussed when the determinate function in reference [1 ] is a/ways equal to zero.
文摘The work presented in this paper is a part of the TLP project undertaken in CSSRC(Chins Ship Scientific Research Center). Model tests were performed in seakeeping basin at CSSRC. Wave envelopes are calculated from time records of the irregular waves using Hilbert transform.Time histories of surge motions of the model were recorded in long-crested irregular head seas.The low-frequency response was separated from the time history using a low pass filter.The quadratic transfer functions were obtained from ratio of the cross-spectrum(between the low-frequency surge response and the square of the wave envelope)and the auto-spectrum of the square of the wave envelope.
文摘This paper introduces a new method to solve Liapunov stability problems for time invariant nonlinear systems—the normal determinative function method. The topic is split into six parts: review of the construction of a V(x) function, the modified Liapunov theorem form while the derivative of V(x) is definite, polynomial features of the analytic system’s normal determinative function V(x), judgment of definitiveness for a polynomial, coefficient direct solution method and the stabilty judgment of critical nonlinear systems, and future research.