We propose an upwind hybrid discontinuous Galerkin (HDG) method for the first-order hyperbolic linear Boltzmann transport equation, featuring a flexible expansion suitable for multiscale scenarios. Within the HDG sche...
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We propose an upwind hybrid discontinuous Galerkin (HDG) method for the first-order hyperbolic linear Boltzmann transport equation, featuring a flexible expansion suitable for multiscale scenarios. Within the HDG scheme, primal variables and numerical traces are introduced within and along faces of elements, respectively, interconnected through projection matrices. Given the variables in two stages, the HDG method offers significant flexibility in the selection of spatial orders. The global matrix system in this framework is exclusively constructed from numerical traces, thereby effectively reducing the degrees of freedom (DoFs). Additionally, the matrix system in each discrete direction features a blocked-lower-triangular stencil, enhancing the efficiency of solving hyperbolic equations through an upwind sweep sequence. Based on the proposed method, we perform an asymptotic analysis of the upwind-HDG method in the thick diffusion limit. The result reveals that the correct convergence of the upwind-HDG is closely associated with the properties of the response matrix L. A series of numerical experiments, including comparisons with the even-parity HDG, confirms the accuracy and stability of the upwind-HDG method in managing thick diffusive regimes and multiscale heterogeneous problems.
The primary loop system of nuclear power plant is a large-scale control system with serious coupling between loops and complex objects. In order to solve the problem of integrated control of primary loop core power, s...
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reactor coolant system is connected with auxiliary pipes, surge pipes and steam pipes. In order to facilitate the dynamic analysis of reactor coolant system, it is necessary to decouple the pipes connected with the re...
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Enormous studies have demonstrated that suitable modification methods, such as micro-structures machining, are adopted to enhance boiling heat transfer performance, especially critical heat flux (CHF) value. This sign...
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To improve the path efficiency for dynamic obstacle avoidance algorithms of Pioneer robots, this paper proposes an approach to create deep deterministic policy gradient (DDPG) smart agents with recurrent neural networ...
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Single-stage neural combinatorial optimization solvers have achieved near-optimal results on various small-scale combinatorial optimization (CO) problems without requiring expert knowledge. However, these solvers exhi...
The heat pipe is the essential component in the heat pipe cooled reactor, it conducts heat through the phase change of the working medium and the circulating flow of gas and liquid. One end of the heat pipe is inserte...
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ISBN:
(纸本)9780791886502
The heat pipe is the essential component in the heat pipe cooled reactor, it conducts heat through the phase change of the working medium and the circulating flow of gas and liquid. One end of the heat pipe is inserted into the reactor as the evaporation section, while the other end serves as the condensation section connecting to the thermoelectric conversion system. Its heat transfer capacity and temperature distribution under a steady state affect the safety, core temperature and energy conversion efficiency of the heat pipe cooled reactorsystem. Predicting the heat transfer process and steady-state temperature distribution of the heat pipe is helpful to learn about the heat transfer mechanism inside the heat pipe and key factors affecting its performance. It is also helpful to predict the operating characteristics of the heat pipe cooled reactorsystem and improve the performance of the heat pipe. The heat pipe is generally considered to be a heat transfer element with good isothermal properties. Past studies, however, proved the significant quantity of its phase-change thermal resistance, resulting in a temperature difference at the gas-liquid interface of the heat pipe that affects the evaporation and condensation. Studies on the relationship between the temperature difference, the working temperature, and heat transfer power of the heat pipe are conductive to building a heat pipe model, to predict the temperature distribution of the heat pipe in a steady state in a much more accurate manner. This paper offered a heat pipe model that applies the temperature difference of the phase change interface to calculate the evaporation and condensation. Meanwhile, a 1-meter-long sodium heat pipe was adopted to carry out steady-state heat transfer experiments. Measured and computed the temperature difference of the phase change interface of the heat pipe under varying power and temperature and conducted the relational equation as the input of the heat pipe model. The mo
The gas-cooled nuclear reactor combined with the closed Brayton cycle is the ideal choice for future high-power space missions, while the helium-xenon mixture is a suitable working medium for the reactor due to its go...
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The integration of multi-agent reinforcement learning (MARL) into complex systems has paved new ways for collaborative problem-solving. However, traditional approaches to MARL frequently encounter the challenge of ach...
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Within the operational dynamics of a nuclear reactor, the customary approach involves modulating the reactor's power output by means of control rod manipulation, which effectively alters the neutron density across...
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