THE APPLICATION OF COMPATIBLE STRESS ITERATIVE METHOD IN DYNAMIC FINITE ELEMENT ANALYSIS OF HIGH VELOCITY IMPACT

There is a common difficulty in elastic-plastic impact codes such as EPIC[2,3] NONSAP[4], etc.. Most of these codes use the simple linear functions usually taken from static problem to represent the displacement components. In such finite element formulation, the stress components are constant in each element and they are discontinuous in any two neighboring elements. Therefore, the bases of using the virtual work principle in such elements are unreliable. In this paper, we introduce a new method, namely, the compatible stress iterative method, to eliminate the above-said difficulty. The calculated examples show that the calculation using the new method in dynamic finite element analysis of high velocity impact is valid and stable, and the element stiffness can be somewhat reduced.

Joint electricity and carbon market for Northeast Asia energy interconnection

Decarbonization of the electricity sector is crucial to mitigate the impacts of climate change and global warming over the coming decades.The key challenges for achieving this goal are carbon emission trading and electricity sector regulation,which are also the major components of the carbon and electricity markets,respectively.In this paper,a joint electricity and carbon market model is proposed to investigate the relationships between electricity price,carbon price,and electricity generation capacity,thereby identifying pathways toward a renewable energy transition under the transactional energy interconnection framework.The proposed model is a dynamically iterative optimization model consisting of upper-level and lower-level models.The upper-level model optimizes power generation and obtains the electricity price,which drives the lower-level model to update the carbon price and electricity generation capacity.The proposed model is verified using the Northeast Asia power grid.The results show that increasing carbon price will result in increased electricity price,along with further increases in renewable energy generation capacity in the following period.This increase in renewable energy generation will reduce reliance on carbon-emitting energy sources,and hence the carbon price will decline.Moreover,the interconnection among zones in the Northeast Asia power grid will enable reasonable allocation of zonal power generation.Carbon capture and storage (CCS) will be an effective technology to reduce the carbon emissions and further realize the emission reduction targets in 2030-2050.It eases the stress of realizing the energy transition because of the less urgency to install additional renewable energy capacity.

PARALLEL DYNAMIC ITERATION METHODS FOR SOLVING NONLINEAR TIME-PERIODIC DIFFERENTIAL-ALGEBRAIC EQUATIONS

In this paper we presented a convergence condition of parallel dynamic iteration methods for a nonlinear system of differential-algebraic equations with a periodic constraint. The convergence criterion is decided by the spectral expression of a linear operator derived from system partitions. Numerical experiments given here confirm the theoretical work of the paper.

Dynamic value iteration networks for the planning of rapidly changing UAV swarms

In an unmanned aerial vehicle ad-hoc network(UANET),sparse and rapidly mobile unmanned aerial vehicles(UAVs)/nodes can dynamically change the UANET topology.This may lead to UANET service performance issues.In this study,for planning rapidly changing UAV swarms,we propose a dynamic value iteration network(DVIN)model trained using the episodic Q-learning method with the connection information of UANETs to generate a state value spread function,which enables UAVs/nodes to adapt to novel physical locations.We then evaluate the performance of the DVIN model and compare it with the non-dominated sorting genetic algorithm II and the exhaustive method.Simulation results demonstrate that the proposed model significantly reduces the decisionmaking time for UAV/node path planning with a high average success rate.

Investigation on Energetic Optimization Problems of Stochastic Thermodynamics with Iterative Dynamic Programming

The energetic optimization problem,e.g.,searching for the optimal switching protocol of certain system parameters to minimize the input work,has been extensively studied by stochastic thermodynamics.In this work,we study this problem numerically using iterative dynamic programming.The model systems under investigation are toy actuators consisting of spring-linked beads with loading force imposed on both ending beads.For the simplest case,i.e.,a one-spring actuator driven by tuning the stiffness of the spring,we compare the optimal control protocol of the stiffness for both the overdamped and the underdamped situations,and discuss how inertial effects alter the irreversibility of the driven process and thus modify the optimal protocol.Then,we study the systems with multiple degrees of freedom by constructing oligomer actuators,in which the harmonic interaction between the two ending beads is tuned externally.With the same rated output work,actuators of different constructions demand different minimal input work,reflecting the influence of the internal degrees of freedom on the performance of the actuators.

Game theoretic analysis of environmental impact assessment system in China

Environmental impact assessment(EIA)system has been established in China since 1973.In present EIA cases,there are four participants in general:governments,enterprises,EIA organizations and the public.The public has held responsible for both social costs and social duties.The public supervises social costs produced by enterprises discharging pollutant in EIA.However public participation is mostly deputized by governments,which severely weaken the independence of the public as one participant in EIA.In this paper,EIA refers to the different attitudes of the par-ticipants whose optional strategies may be described by a proper game model.According to disfigurements in EIA,three sides(governments,enterprises,and EIA organizations)dynamic iterative game theory of many phases is established referring to iterative game theory,dynamic game theory of incomplete information,and perfect Bayesian equilibrium theory to analyze the reciprocity relation among governments,EIA organizations and enterprises.The results show that in a short period,economic benefit is preponderant over social benefit.Governments and enterprises both do not want to take EIA to reveal social costs.EIA organizations’income comes from enterprises and the collusions are built between them to vindicate economic benefit.In a long run,social benefit loss caused by environmental pollution must be recuperated sooner or later and environmental deterioration will influence the achievements of economic benefit,so both governments and enterprises are certain to pursue high social benefit and willing to take EIA,helpful to increase private benefit.EIA organizations will make fair assessment when their economic benefit are ensured.At present,the public as silent victims can not take actual part in EIA.The EIA system must be improved to break the present equilibrium of three sides,bringing the public to the equilibrium to exert public supervision.