Coupling within Fluvial Geomorphic Systems:Spatial and Temporal Implications

Coupling within fluvial systems relates to the connectivity between the various components of the system. It can be viewed at several scales from local scales of hillslopetochannel and reachtoreach coupling, to larger scales of zonal coupling between the major functional zones of the fluvial system, and to the scale of regional coupling. Coupling influences how the system responds to environmental change and how the effects of environmental change are propagated through the system. This paper provides a review, based largely on previously published work, of the coupling concept, and how the effective temporal scales vary with the spatial scale of coupling. Local scale coupling is considered through the hillslope to channel coupling in the Howgill Fells, northwest England, observed over a 30year monitoring period, together with examples from badlands in Spain, and reachtoreach coupling on the River Dane, northwest England. At the zonal scale the relative influence of climatic and baselevel change on coupling through dryregion alluvial fans is considered on fan systems in Spain, Nevada, and UAE/Oman. For large scale regional coupling, the response of the Tabernas basin, southeast Spain to tectonic uplift, is examined. The factors influencing coupling mechanisms vary with temporal and spatial scales. At the hillslopetochannel scale the significant factors are the magnitude and frequency characteristics of sediment generation and removal mechanisms within the context of progressive morphological change. Effective timescales range from the individual event to decadal timescales. At the zonal scale, that of alluvial fans, the significant factors are climatic change, and particularly in the appropriate morphological setting, baselevel change. Effective timescales are of the order of hundreds to thousands of years. At the regional scale, the response to tectonic uplift may take >100 ka to be transmitted through the drainage basin.

通过激光/分散系耦合增强氧化石墨烯的还原效果:实现大规模、低缺陷的石墨烯用于无折痕散热膜在先进柔性电子器件中的应用

The advancement of flexible electronics demands improved components,necessitating heat dissipation membranes(HDMs)to exhibit high thermal conductivity while maintaining structural integrity and performance stability even after extensive deformation.Herein,we have devised a laser-modulated reduction technique for graphene oxide(GO),enabling the fabrication of high-quality,large-scale,lowdefect graphene,which yields high-performance HDMs after orderly deposition.The work underscores the crucial role of the laser wavelength and dispersion liquid's coupling intensity in influencing the morphology and properties of graphene.Optimal coupling effect and energy conversion are realized when a laser of 1064 nm wavelength irradiates a triethylene glycol(TEG)/N,N-Dimethylformamide(DMF)dispersion.This unique synergy generates high transient energy,which facilitates the deprotonation process and ensures a swift,comprehensive GO reduction.In contrast to conventional water-based laser reduction methods,the accelerated reaction magnifies the size of the graphene sheets by mitigating the ablation effect.After membrane construction with an ordered structure,the corresponding membrane exhibits a high thermal conductivity of 1632 W m^(-1)K^(-1),requiring only~1/10 of the total preparation time required by other reported methods.Remarkably,the resulting HDM demonstrates superior resilience against creasing and folding,maintaining excellent smoothness and negligible reduction in thermal conductivity after violent rubbing.The combination of exceptional flexibility and thermal conductivity in HDMs paves the way for long-term practical use in the flexible electronics industry.

A novel multi-fidelity coupled simulation method for flow systems

For the numerical simulation of flow systems with various complex components, the traditional one-dimensional （1D） network method has its comparative advantage in time consuming and the CFD method has its absolute advantage in the detailed flow capturing. The proper coupling of the advantages of different dimensional methods can strike balance well between time cost and accuracy and then significantly decrease the whole design cycle for the flow systems in modern machines. A novel multi-fidelity coupled simulation method with numerical zooming is developed for flow systems. This method focuses on the integration of one-, two-and three-dimensional codes for various components. Coupled iterative process for the different dimensional simulation cycles of sub-systems is performed until the concerned flow variables of the whole system achieve convergence. Numerical zooming is employed to update boundary data of components with different dimen-sionalities. Based on this method, a highly automatic, multi-discipline computing environment with integrated zooming is developed. The numerical results of Y-Junction and the air system of a jet engine are presented to verify the solution method. They indicate that this type of multi-fidelity simulationmethod can greatly improve the prediction capability for the flow systems.