Transient simulation of regression rate on thrust regulation process in hybrid rocket motor

The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion gas.Dynamic mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB（hydroxyl-terminated polybutadiene） hybrid motor have been performed in the flow control process. The simulation results show that under the step change of the oxidizer mass flow rate condition, the regression rate cannot reach a stable value instantly because the flow field requires a short time period to adjust. The regression rate increases with the linear gain of oxidizer mass flow rate, and has a higher slope than the relative inlet function of oxidizer flow rate. A shorter regulation time can cause a higher regression rate during regulation process. The results also show that transient calculation can better simulate the instantaneous regression rate in the operation process.

Randomness in the Hybrid Modeling and Simulation of Insulin Secretion Pathways in Pancreatic Islets

Insulin secreted by pancreatic islet ˇ-cells is the principal regulating hormone of glucose metabolism.Disruption of insulin secretion may cause glucose to accumulate in the blood, and result in diabetes mellitus.Although deterministic models of the insulin secretion pathway have been developed, the stochastic aspect of this biological pathway has not been explored. The first step in this direction presented here is a hybrid model of the insulin secretion pathway, in which the delayed rectifying KCchannels are treated as stochastic events. This hybrid model can not only reproduce the oscillation dynamics as the deterministic model does, but can also capture stochastic dynamics that the deterministic model does not. To measure the insulin oscillation system behavior, a probability-based measure is proposed and applied to test the effectiveness of a new remedy.

Review on Optimization of Nuclear Power Development:A Cyber-Physical-Social System in Energy Perspective

Nuclear power development is a complex issue spanning cyber,physical,and social systems that is essential to achieving energy security and climate goals.With the ongoing worldwide trend towards carbon neutrality,the positioning of nuclear power in energy mix should be reconsidered.This paper aims to present a systematic review of current research on optimization of nuclear power development.The concept of cyber-physical-social system in energy(CPSSE)is adopted,which provides a suitable perspective and enables the review of relevant studies to achieve some novel insights.Based on the CPSSE,firstly,a research framework is established and the main research elements in optimization are identified,followed by a proposed conceptual risk-based optimization model.Secondly,current studies are analyzed and classified into four categories according to the research boundary.The status quo and limitations are discussed.It is found that the research results of nuclear-specific issues have not been well integrated into the optimization of nuclear power.As a relatively reliable power supply,nuclear power is capable of maintaining power and electricity adequacy of the whole system,especially in the case of power shortage caused by long-period low output of renewable energy or extreme external disasters.This superiority should not be ignored in the optimization.Other critical factors that should be further considered include disruptive technologies,nuclear safety,energy policies,and stakeholder behaviors.Finally,suggestions are given for future research.