Effect of anharmonicity on the thermal conductivity of amorphous silica

Proper consideration of anharmonicity is important for the calculation of the thermal conductivity. However, how the anharmonicity influences the thermal conduction in amorphous materials is still an open question. In this work, we uncover the role of anharmonicity on the thermal conductivity of amorphous silica (a-SiO2) by comparing the thermal conductivity predicted from the harmonic theory and the anharmonic theory. Moreover, we explore the effect of anharmonicity-induced frequency shift on the prediction of the thermal conductivity. It is found that the thermal conductivity calculated by the recently developed anharmonic theory (quasi-harmonic Green-Kubo approximation, QHGK) is higher than that by the harmonic theory developed by Allen and Feldman. The use of anharmonic vibrational frequencies also leads to a higher thermal conductivity compared with that calculated using harmonic vibrational frequencies. The anharmonicity induced frequency shifts is a mechanism for the positive temperature dependence of the thermal conductivity of a-SiO2 at higher temperatures. Further investigation on mode diffusivity suggests that although anharmonicity has larger influence on locons than diffusons, the increase of the thermal conductivity due to the anharmonicity is mainly contributed by the anharmonicity induced increase of the diffusivity of diffusons. Finally, it is found that the cross-correlations between diffusons and diffusons contribute most to the thermal conductivity of a-SiO2, and the locons contribute to the thermal conductivity mainly through collaboration with diffusons. These results offer new insights into the nature of the thermal conduction in a-SiO2

Determination method of the structure size interval of dynamic similar models for predicting vibration characteristics of the isotropic sandwich plates

A method is studied for determining the structure size interval of dynamic similar models of the isotropic sandwich plates. Firstly, a comparison between the two theories of plates, the Resineer theory and the Hoff theory, is conducted, including their governing equations and the ANSYS analytic solutions of frequency. The Resineer theory is chosen as the basic theory of this paper finally. Secondly, the scaling laws between the model and prototype of isotropic sandwich plate are established by combining the dimensional analysis and governing analysis. Both complete and incomplete geometric similarity conditions are discussed. Thirdly, the determination method of the structure size interval of the models is proposed. The nature vibration mode keeps the same and the nature frequency and harmonic response keep in proportion with the prototype of the sandwich plate. At last, the flow step of the intervals determination method is given

STEAM GASIFICATION OF LOW RANK COAL CHARS IN A THERMOBALANCE REACTOR AND A FLUIDIZED BED REACTOR

The six chars of low rank coals have been gasified with steam in a thermobalance reactor and one lignite in a fluidized bed to obtain the kinetic information needed for a design of coal gasifier. The gas-solid reaction models have been compared for their prediction ability of the gasification reaction behavior. The apparent reaction rate equations have been presented

Study of the structure size interval of incomplete geometrically similitude model of the elastic thin plates

To design the similitude test model having the same nature characteristics with the prototype of the elastic thin plates, an innovative method of confirm the structure size applicable interval of distorted (incomplete geometrically) similar model was proposed. Firstly, the complete scaling laws and the distortion scaling laws between the model and its prototype were established by using the governing equation analysis. Then, under the study of the structure size applicable interval which kept the same first-order nature characteristic (nature frequency and vibration mode), through the research of the vibration mode control interval (each order of the mode keep the same) and the predict interval of frequency, the method of structure size applicable interval of distorted similar model was obtained, which they were in different orders with the same nature characteristic. Finally, the proposed calculation method is verified by experiment

Lurasidone hydro­chloride

In the crystal structure of the title compound, C28H37N4O2S+·Cl− [systematic name: 4-(1,2-benzothia­zol-3-yl)-1-({2-[(3,5-dioxo-4-aza­tricyclo­[5.2.1.02,6]decan-4-yl)meth­yl]cyclo­hex­yl}meth­yl)piperazin-1-ium chloride], the anions and cations are linked by N—H⋯Cl hydrogen bonds. The crystal structure is further stabilized by C—H⋯π and C—H⋯O inter­actions

Study of the structure size interval of incomplete geometrically similitude model of the elastic thin plates

To design the similitude test model having the same nature characteristics with the prototype of the elastic thin plates, an innovative method of confirm the structure size applicable interval of distorted (incomplete geometrically) similar model was proposed. Firstly, the complete scaling laws and the distortion scaling laws between the model and its prototype were established by using the governing equation analysis. Then, under the study of the structure size applicable interval which kept the same first-order nature characteristic (nature frequency and vibration mode), through the research of the vibration mode control interval (each order of the mode keep the same) and the predict interval of frequency, the method of structure size applicable interval of distorted similar model was obtained, which they were in different orders with the same nature characteristic. Finally, the proposed calculation method is verified by experiment