The dispersive property of the mode Grüneisen parameter in solids is found theoretically.Such a property should appear in a reciprocal relationship to the mode frequency.This phenomenon is also confirmed experime...The dispersive property of the mode Grüneisen parameter in solids is found theoretically.Such a property should appear in a reciprocal relationship to the mode frequency.This phenomenon is also confirmed experimentally in the cases of corundum andα-quartz.展开更多
Dynamic mechanical performances of 30CrMnSiNi2A alloy steel under high pressure of 1-15 GPa are studied with a one stage light gas gun. With the particle velocity ranging from 150 m/s to 300 m/s, the Hugoniot curve ...Dynamic mechanical performances of 30CrMnSiNi2A alloy steel under high pressure of 1-15 GPa are studied with a one stage light gas gun. With the particle velocity ranging from 150 m/s to 300 m/s, the Hugoniot curve of 30CrMnSiNi2A alloy steel is analyzed and obtained based on the experimental data and the parameters of equation of state are obtained by calculating. The Grüneisen equation of state can be determined through these parameters.展开更多
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
The temperature dependence of the ultrasonic parameters like ultrasonic velocities and Grüneisen parameters in americium monopnictides AmY (Y: N, P, As, Sb and Bi) have been studied for longitudinal and shear wav...The temperature dependence of the ultrasonic parameters like ultrasonic velocities and Grüneisen parameters in americium monopnictides AmY (Y: N, P, As, Sb and Bi) have been studied for longitudinal and shear waves along , and crystallographic directions in the temperature range 100 K - 500 K. The second- and third- order elastic constants have also been evaluated for these monopnictides using Coulomb and Born-Mayer potential. The values of elastic constants are the highest for AmN. Hence the mechanical properties of AmN are better than other monopnictides AmP, AmAs, AmSb and AmBi. Ultrasonic velocity is found large for AmP. So the ultrasonic wave propagation will be much better than others in AmP. Obtained results are compared with available results of same type of materials.展开更多
The first justified theory of solid state was proposed by Grüneisen in the year 1912 and was based on the virial theorem. The forces of interaction between two atoms were assumed as changing with distance between...The first justified theory of solid state was proposed by Grüneisen in the year 1912 and was based on the virial theorem. The forces of interaction between two atoms were assumed as changing with distance between them according to inverse power laws. But only virial theorem is insufficient to deduce the equation of state, so this author has introduced some relations, which are correct, when the forces linearly depend on displacement of atoms. But with such law of interaction the phase transitions cannot take place. Debye received Grüneisen equation in another way. He deduced the expression for thermocapacity, using Plank formula for energy of harmonic vibrator. Taking into account the dependence of atomic vibration frequency from distance between atoms, when the forces of interaction are anharmonic, he received the equation of state, which in classical limit turns to Grüneisen equation. The question, formulated by Debye is—How can we come to phase transitions, when Plank formula for harmonic vibrator was used? Debye solved this question not perfectly, because he was born to small anharmonicity. In the presented work a chain of atoms is considered, and their movement is analysed by means of relations, equivalent to virial theorem and theorem of Lucas (disappearing of mean force). Both are the results of variation principle of Hamilton. The Grüneisen equation for low temperature (not very low, where quantum expression for energy is essential) was obtained, and a family of isotherms and isobars are drown, which show the existence of spinodals, where phase transitions occur. So, Grüneisen equation is an equation of state for low temperatures.展开更多
Open framework structures(e.g.,ScF_(3),Sc_(2)W_(3O)_(12),etc.)exhibit significant potential for thermal expansion tailoring owing to their high atomic vibrational degrees of freedom and diverse connectivity between po...Open framework structures(e.g.,ScF_(3),Sc_(2)W_(3O)_(12),etc.)exhibit significant potential for thermal expansion tailoring owing to their high atomic vibrational degrees of freedom and diverse connectivity between polyhedral units,displaying positive/negative thermal expansion(PTE/NTE)coefficients at a certain temperature.Despite the proposal of several physical mechanisms to explain the origin of NTE,an accurate mapping relationship between the structural–compositional properties and thermal expansion behavior is still lacking.This deficiency impedes the rapid evaluation of thermal expansion properties and hinders the design and development of such materials.We developed an algorithm for identifying and characterizing the connection patterns of structural units in open-framework structures and constructed a descriptor set for the thermal expansion properties of this system,which is composed of connectivity and elemental information.Our developed descriptor,aided by machine learning(ML)algorithms,can effectively learn the thermal expansion behavior in small sample datasets collected from literature-reported experimental data(246 samples).The trained model can accurately distinguish the thermal expansion behavior(PTE/NTE),achieving an accuracy of 92%.Additionally,our model predicted six new thermodynamically stable NTE materials,which were validated through first-principles calculations.Our results demonstrate that developing effective descriptors closely related to thermal expansion properties enables ML models to make accurate predictions even on small sample datasets,providing a new perspective for understanding the relationship between connectivity and thermal expansion properties in the open framework structure.The datasets that were used to support these results are available on Science Data Bank,accessible via the link https://doi.org/10.57760/sciencedb.j00113.00100.展开更多
Grüneisen parameter is one of the most valuable quantities in thermodynamics, which links the material properties of bulk modulus, heat capacity at constant volume, thermal expansion coefficient, and volume toget...Grüneisen parameter is one of the most valuable quantities in thermodynamics, which links the material properties of bulk modulus, heat capacity at constant volume, thermal expansion coefficient, and volume together. A new thermodynamic model of temperature-dependent potential energy is proposed here to investigate the temperature dependent Grüneisen parameter of bulk material. The newly developed thermodynamic model leads to temperature dependent analytical solutions of Grüneisen parameter and other thermo-mechanical properties including the Grüneisen equation of state. Molecular dynamics simulations are conducted on single crystalline Ni, Cu, and Au bulk crystals and the simulation results verify the newly developed thermodynamic model and quantitively evaluate the theoretically derived physical quantities. In addition, the Debye model is also employed in the study of temperature dependent Grüneisen parameter and the results also verify the theoretical approach.展开更多
Almost all European countries use at least two horizontal reference systems, which allow them to minimize all risks when changing the coordinate system. The first system is used for the needs of the national survey in...Almost all European countries use at least two horizontal reference systems, which allow them to minimize all risks when changing the coordinate system. The first system is used for the needs of the national survey in general, and also for technical applications in engineering surveys. A brief description of this system can be written by the formula: Geocentric Ellipsoid(GRS80) + Projection(UTM). More than half of the European countries for the second national systems use the GRS80 geocentric ellipsoid together with a projection other than UTM, some of them continue to use the projection of the old coordinate systems. The rest of the countries, excluding Ukraine, adapted the existing national coordinate systems to modern requirements, removing deformations from them concerning the ETRS89. A small number of European countries have implemented the GRS80 geocentric ellipsoid together with the UTM projection for cadastral surveys and topographic maps with a scale of 1:5000 and larger. Only one country, Ukraine, chose a variant for the new coordinate system(UCS2000), which is briefly written by the formula: Old Not Geocentric Ellipsoid + New Projection. The analysis of modern coordinate systems of Europe made it possible to formulate two variants of the future coordinate system of Ukraine based on a geocentric ellipsoid. It is shown that the transition to a geocentric ellipsoid will change the coordinates and heights of the points, but practically will not change the distance between the points and the area of the parcels.展开更多
文摘The dispersive property of the mode Grüneisen parameter in solids is found theoretically.Such a property should appear in a reciprocal relationship to the mode frequency.This phenomenon is also confirmed experimentally in the cases of corundum andα-quartz.
文摘Dynamic mechanical performances of 30CrMnSiNi2A alloy steel under high pressure of 1-15 GPa are studied with a one stage light gas gun. With the particle velocity ranging from 150 m/s to 300 m/s, the Hugoniot curve of 30CrMnSiNi2A alloy steel is analyzed and obtained based on the experimental data and the parameters of equation of state are obtained by calculating. The Grüneisen equation of state can be determined through these parameters.
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The temperature dependence of the ultrasonic parameters like ultrasonic velocities and Grüneisen parameters in americium monopnictides AmY (Y: N, P, As, Sb and Bi) have been studied for longitudinal and shear waves along , and crystallographic directions in the temperature range 100 K - 500 K. The second- and third- order elastic constants have also been evaluated for these monopnictides using Coulomb and Born-Mayer potential. The values of elastic constants are the highest for AmN. Hence the mechanical properties of AmN are better than other monopnictides AmP, AmAs, AmSb and AmBi. Ultrasonic velocity is found large for AmP. So the ultrasonic wave propagation will be much better than others in AmP. Obtained results are compared with available results of same type of materials.
文摘The first justified theory of solid state was proposed by Grüneisen in the year 1912 and was based on the virial theorem. The forces of interaction between two atoms were assumed as changing with distance between them according to inverse power laws. But only virial theorem is insufficient to deduce the equation of state, so this author has introduced some relations, which are correct, when the forces linearly depend on displacement of atoms. But with such law of interaction the phase transitions cannot take place. Debye received Grüneisen equation in another way. He deduced the expression for thermocapacity, using Plank formula for energy of harmonic vibrator. Taking into account the dependence of atomic vibration frequency from distance between atoms, when the forces of interaction are anharmonic, he received the equation of state, which in classical limit turns to Grüneisen equation. The question, formulated by Debye is—How can we come to phase transitions, when Plank formula for harmonic vibrator was used? Debye solved this question not perfectly, because he was born to small anharmonicity. In the presented work a chain of atoms is considered, and their movement is analysed by means of relations, equivalent to virial theorem and theorem of Lucas (disappearing of mean force). Both are the results of variation principle of Hamilton. The Grüneisen equation for low temperature (not very low, where quantum expression for energy is essential) was obtained, and a family of isotherms and isobars are drown, which show the existence of spinodals, where phase transitions occur. So, Grüneisen equation is an equation of state for low temperatures.
基金the National Natural Science Foundation of China(Grant Nos.12004131,22090044,62125402,and 92061113)。
文摘Open framework structures(e.g.,ScF_(3),Sc_(2)W_(3O)_(12),etc.)exhibit significant potential for thermal expansion tailoring owing to their high atomic vibrational degrees of freedom and diverse connectivity between polyhedral units,displaying positive/negative thermal expansion(PTE/NTE)coefficients at a certain temperature.Despite the proposal of several physical mechanisms to explain the origin of NTE,an accurate mapping relationship between the structural–compositional properties and thermal expansion behavior is still lacking.This deficiency impedes the rapid evaluation of thermal expansion properties and hinders the design and development of such materials.We developed an algorithm for identifying and characterizing the connection patterns of structural units in open-framework structures and constructed a descriptor set for the thermal expansion properties of this system,which is composed of connectivity and elemental information.Our developed descriptor,aided by machine learning(ML)algorithms,can effectively learn the thermal expansion behavior in small sample datasets collected from literature-reported experimental data(246 samples).The trained model can accurately distinguish the thermal expansion behavior(PTE/NTE),achieving an accuracy of 92%.Additionally,our model predicted six new thermodynamically stable NTE materials,which were validated through first-principles calculations.Our results demonstrate that developing effective descriptors closely related to thermal expansion properties enables ML models to make accurate predictions even on small sample datasets,providing a new perspective for understanding the relationship between connectivity and thermal expansion properties in the open framework structure.The datasets that were used to support these results are available on Science Data Bank,accessible via the link https://doi.org/10.57760/sciencedb.j00113.00100.
基金supported by the National Key R&D Program of China(Grant No.2017YFB0701604)the National Natural Science Foundation of China(Grant Nos.11672168&11802169)
文摘Grüneisen parameter is one of the most valuable quantities in thermodynamics, which links the material properties of bulk modulus, heat capacity at constant volume, thermal expansion coefficient, and volume together. A new thermodynamic model of temperature-dependent potential energy is proposed here to investigate the temperature dependent Grüneisen parameter of bulk material. The newly developed thermodynamic model leads to temperature dependent analytical solutions of Grüneisen parameter and other thermo-mechanical properties including the Grüneisen equation of state. Molecular dynamics simulations are conducted on single crystalline Ni, Cu, and Au bulk crystals and the simulation results verify the newly developed thermodynamic model and quantitively evaluate the theoretically derived physical quantities. In addition, the Debye model is also employed in the study of temperature dependent Grüneisen parameter and the results also verify the theoretical approach.
文摘Almost all European countries use at least two horizontal reference systems, which allow them to minimize all risks when changing the coordinate system. The first system is used for the needs of the national survey in general, and also for technical applications in engineering surveys. A brief description of this system can be written by the formula: Geocentric Ellipsoid(GRS80) + Projection(UTM). More than half of the European countries for the second national systems use the GRS80 geocentric ellipsoid together with a projection other than UTM, some of them continue to use the projection of the old coordinate systems. The rest of the countries, excluding Ukraine, adapted the existing national coordinate systems to modern requirements, removing deformations from them concerning the ETRS89. A small number of European countries have implemented the GRS80 geocentric ellipsoid together with the UTM projection for cadastral surveys and topographic maps with a scale of 1:5000 and larger. Only one country, Ukraine, chose a variant for the new coordinate system(UCS2000), which is briefly written by the formula: Old Not Geocentric Ellipsoid + New Projection. The analysis of modern coordinate systems of Europe made it possible to formulate two variants of the future coordinate system of Ukraine based on a geocentric ellipsoid. It is shown that the transition to a geocentric ellipsoid will change the coordinates and heights of the points, but practically will not change the distance between the points and the area of the parcels.
