Dynamic equations controlling the thermally-driven fluid convection in a single rock crack are established in the paper . The critical criteria for the onset of convection in such a configuration are found by linear d...Dynamic equations controlling the thermally-driven fluid convection in a single rock crack are established in the paper . The critical criteria for the onset of convection in such a configuration are found by linear dynamic analysis of the equations and the stability of the convection discussed by nonlinear analysis method . The research demonstrates that the critical Rayleigh number has a magnitude 103. While the Rayleigh number R of real ore-forming fluids exceeds this value , the convection happens , and as R becomes larger , the fluid convection pattern develops from nonequilibrium steady states to double-periodically produced limit cycles and eventually to chaos (turbulences ).The implication of these dynamic analyses for the ore-forming processes of late-magma tic hydrothermal deposits is also discussed in the paper .展开更多
Artificial muscle fibers driven electrothermally with excellent properties of response,stroke,and work capacity are expected to serve in some intelligent structures and systems.However,muscle fibers that operate in su...Artificial muscle fibers driven electrothermally with excellent properties of response,stroke,and work capacity are expected to serve in some intelligent structures and systems.However,muscle fibers that operate in subzero environments are highly needed in industrial production and aerospace applications but remain challenging.Herein,we reported a coaxial artificial muscle fiber by electrospinning a sheath of polycaprolactone(PCL)nanofibers on the surface of a carbon nanotube(CNT)fiber core,achieving the actuation in response to thermal at subzero temperatures.The CNT@PCL coaxial muscle fiber under 0.3 MPa achieved a maximum contractile stroke of~18%as the temperature changed from−130℃ to 45℃.The actuation mechanism at subzero temperatures of this muscle fiber was analyzed in combination with the temperature-deformation schematic curve of different polymers.Furthermore,a temperature sensor based on this muscle fiber was developed,due to the excellent linear relationship between the contraction and temperature.A 3D-printed prosthetic arm was designed to further exhibit the application demonstrations of this muscle fiber in subzero environments.This work provides new insights into artificial muscle fibers for serving in extreme environments with ultralow temperatures.展开更多
发展大规模、分布式储能是实现“双碳”目标的重要途径。守住储能电池(battery energy storage,BES)的安全底线关乎人民生命安全和社会经济发展。现有储能电池安全预警方法还面临如下2个方面挑战:机理研究方法考虑的工况单一,难以推广应...发展大规模、分布式储能是实现“双碳”目标的重要途径。守住储能电池(battery energy storage,BES)的安全底线关乎人民生命安全和社会经济发展。现有储能电池安全预警方法还面临如下2个方面挑战:机理研究方法考虑的工况单一,难以推广应用;基于有监督学习的数据驱动方法难以有效应对小样本问题。对此,提出基于重构误差计算的数据驱动储能电池热失控预警方法。首先,基于无监督学习思想,建立数据驱动的储能电池热失控预警框架,利用重构误差构建电池间的差异程度,可有效应对小样本场景;利用集成学习思想量化电池热失控概率,可保障算法的稳定性。然后,为有效提取储能电池电压、温度、电流、荷电状态(stateof charge,SOC)等数据的时变特性,高效挖掘热失控前后的时变数据特征差异,进一步提出基于双向长短期记忆(bi-long short-term memory,Bi-LSTM)网络与注意力机制的储能电池数据特征挖掘方法,实现储能电池数据特征的精准学习。最后,通过电动汽车动力电池的真实运行数据,验证了所提方法的有效性。展开更多
文摘Dynamic equations controlling the thermally-driven fluid convection in a single rock crack are established in the paper . The critical criteria for the onset of convection in such a configuration are found by linear dynamic analysis of the equations and the stability of the convection discussed by nonlinear analysis method . The research demonstrates that the critical Rayleigh number has a magnitude 103. While the Rayleigh number R of real ore-forming fluids exceeds this value , the convection happens , and as R becomes larger , the fluid convection pattern develops from nonequilibrium steady states to double-periodically produced limit cycles and eventually to chaos (turbulences ).The implication of these dynamic analyses for the ore-forming processes of late-magma tic hydrothermal deposits is also discussed in the paper .
基金The authors acknowledge the financial support obtained from Key Research Project of Zhejiang lab(No.K2022NB0AC04)the National Key Research and Development Program of China(2020YFB1312900)+1 种基金the National Natural Science Foundation of China(21975281)Jiangxi Double Thousand Talent Program(No.jxsq2020101008)。
文摘Artificial muscle fibers driven electrothermally with excellent properties of response,stroke,and work capacity are expected to serve in some intelligent structures and systems.However,muscle fibers that operate in subzero environments are highly needed in industrial production and aerospace applications but remain challenging.Herein,we reported a coaxial artificial muscle fiber by electrospinning a sheath of polycaprolactone(PCL)nanofibers on the surface of a carbon nanotube(CNT)fiber core,achieving the actuation in response to thermal at subzero temperatures.The CNT@PCL coaxial muscle fiber under 0.3 MPa achieved a maximum contractile stroke of~18%as the temperature changed from−130℃ to 45℃.The actuation mechanism at subzero temperatures of this muscle fiber was analyzed in combination with the temperature-deformation schematic curve of different polymers.Furthermore,a temperature sensor based on this muscle fiber was developed,due to the excellent linear relationship between the contraction and temperature.A 3D-printed prosthetic arm was designed to further exhibit the application demonstrations of this muscle fiber in subzero environments.This work provides new insights into artificial muscle fibers for serving in extreme environments with ultralow temperatures.
