Parallel energy stable phase field simulations of Ni-based alloys system

In this paper, we investigate numerical methods for solving Nickel-based phase field system related to free energy, including the elastic energy and logarithmic type functionals. To address the challenge posed by the particular free energy functional, we propose a semi-implicit scheme based on the discrete variational derivative method, which is unconditionally energy stable and maintains the energy dissipation law and the mass conservation law. Due to the good stability of the semi-implicit scheme, the adaptive time step strategy is adopted, which can flexibly control the time step according to the dynamic evolution of the problem. A domain decomposition based, parallel Newton--Krylov--Schwarz method is introduced to solve the nonlinear algebraic system constructed by the discretization at each time step. Numerical experiments show that the proposed algorithm is energy stable with large time steps, and highly scalable to six thousand processor cores.Comment: arXiv admin note: text overlap with arXiv:2007.0456

GLOBAL REGULARITY AND MULTISCALE APPROACH FOR THERMAL RADIATION HEAT TRANSFER

This paper discusses the multiscale analysis for the thermal radiation heat transfer in composite materials with a periodic microstructure. The new contributions reported in this paper are threefold: global existence of the solution for the nonlinear equation with discontinuous coefficients is proved by using Rothe's method, the multiscale asymptotic expansions of the solution for the thermal radiation heat transfer equation with rapidly oscillating coefficients are presented, and the convergence results between the original solution u(epsilon)( x, t) and the multiscale asymptotic solutions with an explicit convergence rate are obtained.This paper discusses the multiscale analysis for the thermal radiation heat transfer in composite materials with a periodic microstructure. The new contributions reported in this paper are threefold: global existence of the solution for the nonlinear equation with discontinuous coefficients is proved by using Rothe's method, the multiscale asymptotic expansions of the solution for the thermal radiation heat transfer equation with rapidly oscillating coefficients are presented, and the convergence results between the original solution u(epsilon)( x, t) and the multiscale asymptotic solutions with an explicit convergence rate are obtained

a molecular dynamics-continuum coupled model for heat transfer in composite materials

The heat transfer problem in composite materials containing nanoscale interfaces is investigated. A molecular dynamics-continuum coupled model is developed to study heat transport from the macro- to the microscales. The model includes four major steps: (1) A reverse nonequilibrium molecular dynamics (RNEMD) method is used to calculate some physical parameters such as the thermal conductivities on the interface. (2) The homogenization method is applied to compute the homogenized thermal conductivities of composite materials. (3) The temperature field in the global structure of composite materials is computed with the multiscale asymptotic method for the macroscopic heat transfer equation. (4) A molecular dynamics-continuum coupled model is developed to reevaluate the temperature field of composite materials, in particular, the local temperature field near the interface. Numerical results in one-, two-, and three-dimensional structures of composite materials including the nanoscale interface are given. Good agreement is achieved between the numerical results of the proposed coupled algorithm and those of the full molecular dynamics simulation, demonstrating the accuracy of the present method and its potential applications in thermal engineering of composite materials. © 2012 SIAM.The heat transfer problem in composite materials containing nanoscale interfaces is investigated. A molecular dynamics-continuum coupled model is developed to study heat transport from the macro- to the microscales. The model includes four major steps: (1) A reverse nonequilibrium molecular dynamics (RNEMD) method is used to calculate some physical parameters such as the thermal conductivities on the interface. (2) The homogenization method is applied to compute the homogenized thermal conductivities of composite materials. (3) The temperature field in the global structure of composite materials is computed with the multiscale asymptotic method for the macroscopic heat transfer equation. (4) A molecular dynamics-continuum coupled model is developed to reevaluate the temperature field of composite materials, in particular, the local temperature field near the interface. Numerical results in one-, two-, and three-dimensional structures of composite materials including the nanoscale interface are given. Good agreement is achieved between the numerical results of the proposed coupled algorithm and those of the full molecular dynamics simulation, demonstrating the accuracy of the present method and its potential applications in thermal engineering of composite materials. © 2012 SIAM

Promoting the Transformation of Old Industrial Bases Through Energy Revolution

The old industrial bases in China are facing various problems and challenges owing to the contradiction between the institutional mechanism and economic structure, and energy revolution is an important support for the transformation of these old industrial bases. In this study, the basic characteristics and development status of the old industrial bases in Northeast China and Shanxi are elaborated, the key problems regarding energy transformation in these places are analyzed. Moreover, an energy transition strategy is proposed for the old industrial bases, and strategic measures and policy suggestions are offered. Through quantitative analysis and strategic study, we expound the connotation and strategic positioning of energy revolution in the old industrial bases and propose the strategic goals for the transformation of the old industrial bases by 2035 and 2050. To transform and upgrade the energy industry in the old industrial bases and optimize the energy production and consumption modes, the following measures are proposed: constructing a special energy economic zone within Shanxi, Eastern Inner Mongolia, and Northeast China; encouraging shale oil development; promoting the comprehensive utilization of abandoned oil and gas reservoirs and abandoned mines; supporting the transformation of resource-dependent areas; promoting diversified utilization of fossil energy resources; building a demonstration base for diversified utilization of renewable energy; and establishing a talent incentive policy mechanism

Potential Application Performance of Hydrochar from Kitchen Waste: Effects of Salt, Oil, Moisture, and pH

The surge in kitchen waste production is causing food-borne disease epidemics and is a public health threat worldwide. Additionally, the effectiveness of conventional treatment approaches may be hampered by KW’s high moisture, salt, and oil content. Hydrothermal carbonization (HTC) is a promising new technology to convert waste biomass into environmentally beneficial derivatives. This study used simulated KW to determine the efficacy of hydrothermal derivatives (hydrochar) with different salt and oil content, pH value, and solid-liquid ratio for the removal of cadmium (Cd) from water and identify their high heating value (HHV). The findings revealed that the kitchen waste hydrochar (KWHC) yield decreased with increasing oil content. When the water content in the hydrothermal system increased by 90%, the yield of KWHC decreased by 65.85%. The adsorption capacity of KWHC remained stable at different salinities. The KWHC produced in the acidic environment increases the removal efficiency of KWHC for Cd. The raw material was effectively transformed into a maximum HHV (30.01 MJ/kg). HTC is an effective and secure method for the resource utilization of KW based on the adsorption capacity and combustion characteristic indices of KWHC