In this paper, the viscoelsatic boundary layer flow and the heat transfer near a vertical isothermal impermeable surface and in a quiescent fluid are examined. The governing equations are formulated and solved numeric...In this paper, the viscoelsatic boundary layer flow and the heat transfer near a vertical isothermal impermeable surface and in a quiescent fluid are examined. The governing equations are formulated and solved numerically using MackCormak＇s technique. The results show excellent agreement with previously published results by a comparision. Representative results for the velocity and temperature profiles, boundary layer thicknesses, Nusselt numbers, and local skin friction coefficients are shown graphically for different values of viscoelsatic parameters. In general, it is found that the velocities increase inside the hydrodynamic boundary layers and the temperatures decrease inside the thermal boundary layers for the viscoelsatic fluid as compared with the Newtonian fluid due to favorable tensile stresses. Consequently, the coefficients of friction and heat transfer enhance for higher viscoelsatic parameters.展开更多
In this paper,the isogeometric analysis(IGA)method is employed to analyze the oscillation characteristics of functionally graded triply periodic minimal surface(FG-TPMS)curved-doubly shells integrated with magneto-ele...In this paper,the isogeometric analysis(IGA)method is employed to analyze the oscillation characteristics of functionally graded triply periodic minimal surface(FG-TPMS)curved-doubly shells integrated with magneto-electric surface layers(referred to as"FG-TPMS-MEE curved-doubly shells")subjected to low-velocity impact loads.This study presents low-velocity impact load model based on a single springmass(S-M)approach.The FG-TPMS-MEE curved-doubly shells are covered with two magneto-electric surface layers,while the core layer consists of three types:I-graph and Wrapped Package-graph(IWP),Gyroid(G),and Primitive(P),with various graded functions.These types are notable for their exceptional stiffness-to-weight ratios,enabling a wide range of potential applications.The Maxwell equations and electromagnetic boundary conditions are applied to compute the change in electric potentials and magnetic potentials.The equilibrium equations of the shell are derived from a refined higher-order shear deformation theory(HSDT),and the transient responses of the FG-TPMS-MEE curveddoubly shells are subsequently determined using Newmark's direct integration method.These results have applications in structural vibration control and the analysis of structures subjected to impact or explosive loads.Furthermore,this study provides a theoretical prediction of the low-velocity impact load and magneto-electric-elastic effects on the free vibration and transient response of FG-TPMS-MEE curved-doubly shells.展开更多
Transient electronics,which can be controllably broken down with zero environmental impact,hold significant potential in implantable devices,hardware security,and disposable sensors.While miniaturization is essential ...Transient electronics,which can be controllably broken down with zero environmental impact,hold significant potential in implantable devices,hardware security,and disposable sensors.While miniaturization is essential for enhancing device performance,increasing integration density,and enabling new applications,degradable materials often face challenges with conventional microfabrication processes like lithography due to their sensitivity to heat and solvents.In this paper,we present a UV photodetector(PD)with micro-scale patterning,fabricated using a novel solvent-free material patterning method.The PD,consisting of molybdenum(Mo)as the electrode,zinc oxide(ZnO)as the photoactive material,and polyvinyl alcohol(PVA)as the substrate,can be dissolved in deionized(DI)water,leaving behind non-toxic byproducts.The device exhibits high responsivity over 50 A/W and an obvious response to varying sunlight intensities,demonstrating its potential for temporary,eco-friendly UV sensing applications.Additionally,we demonstrated that the photoresist used in the solvent-free material patterning method can be reused for subsequent fabrication while maintaining good registration,enhancing efficiency and reducing material waste.This approach provides a scalable and high-efficiency microfabrication strategy for integrating functional materials into unconventional platforms,offering broader applicability in next-generation transient,biodegradable,and flexible sensor technologies.展开更多
将跟踪微分器加入到无模型自适应控制器中,结合跟踪微分器与无模型自适应控制器的优点,设计出一种适合于诸如非线性、时滞、时变、强耦合等复杂系统的控制器。该控制器利用跟踪微分器安排过渡过程,实现了对强干扰、大时滞系统的快速、...将跟踪微分器加入到无模型自适应控制器中,结合跟踪微分器与无模型自适应控制器的优点,设计出一种适合于诸如非线性、时滞、时变、强耦合等复杂系统的控制器。该控制器利用跟踪微分器安排过渡过程,实现了对强干扰、大时滞系统的快速、无超调控制,并且进行了与非线性PID(proportional integral derivative)控制器的对比仿真研究。仿真结果表明:带有跟踪微分器的无模型自适应控制器具有的优点,适合于处理带有强干扰以及时滞系统的控制问题。展开更多
文摘In this paper, the viscoelsatic boundary layer flow and the heat transfer near a vertical isothermal impermeable surface and in a quiescent fluid are examined. The governing equations are formulated and solved numerically using MackCormak＇s technique. The results show excellent agreement with previously published results by a comparision. Representative results for the velocity and temperature profiles, boundary layer thicknesses, Nusselt numbers, and local skin friction coefficients are shown graphically for different values of viscoelsatic parameters. In general, it is found that the velocities increase inside the hydrodynamic boundary layers and the temperatures decrease inside the thermal boundary layers for the viscoelsatic fluid as compared with the Newtonian fluid due to favorable tensile stresses. Consequently, the coefficients of friction and heat transfer enhance for higher viscoelsatic parameters.
文摘In this paper,the isogeometric analysis(IGA)method is employed to analyze the oscillation characteristics of functionally graded triply periodic minimal surface(FG-TPMS)curved-doubly shells integrated with magneto-electric surface layers(referred to as"FG-TPMS-MEE curved-doubly shells")subjected to low-velocity impact loads.This study presents low-velocity impact load model based on a single springmass(S-M)approach.The FG-TPMS-MEE curved-doubly shells are covered with two magneto-electric surface layers,while the core layer consists of three types:I-graph and Wrapped Package-graph(IWP),Gyroid(G),and Primitive(P),with various graded functions.These types are notable for their exceptional stiffness-to-weight ratios,enabling a wide range of potential applications.The Maxwell equations and electromagnetic boundary conditions are applied to compute the change in electric potentials and magnetic potentials.The equilibrium equations of the shell are derived from a refined higher-order shear deformation theory(HSDT),and the transient responses of the FG-TPMS-MEE curveddoubly shells are subsequently determined using Newmark's direct integration method.These results have applications in structural vibration control and the analysis of structures subjected to impact or explosive loads.Furthermore,this study provides a theoretical prediction of the low-velocity impact load and magneto-electric-elastic effects on the free vibration and transient response of FG-TPMS-MEE curved-doubly shells.
基金supported by the National Natural Science Foundation of China(No.52375580)the Guangdong Basic and Applied Basic Research Foundation(No.2024A1515011397)+2 种基金the Department of Education of Guangdong Province(No.2023ZDZX1036)the Guangzhou-HKUST(GZ)Joint Funding Program(No.2023A03J0688)the Guangzhou Basic and Applied Basic Research Scheme(No.2024A04J6466).
文摘Transient electronics,which can be controllably broken down with zero environmental impact,hold significant potential in implantable devices,hardware security,and disposable sensors.While miniaturization is essential for enhancing device performance,increasing integration density,and enabling new applications,degradable materials often face challenges with conventional microfabrication processes like lithography due to their sensitivity to heat and solvents.In this paper,we present a UV photodetector(PD)with micro-scale patterning,fabricated using a novel solvent-free material patterning method.The PD,consisting of molybdenum(Mo)as the electrode,zinc oxide(ZnO)as the photoactive material,and polyvinyl alcohol(PVA)as the substrate,can be dissolved in deionized(DI)water,leaving behind non-toxic byproducts.The device exhibits high responsivity over 50 A/W and an obvious response to varying sunlight intensities,demonstrating its potential for temporary,eco-friendly UV sensing applications.Additionally,we demonstrated that the photoresist used in the solvent-free material patterning method can be reused for subsequent fabrication while maintaining good registration,enhancing efficiency and reducing material waste.This approach provides a scalable and high-efficiency microfabrication strategy for integrating functional materials into unconventional platforms,offering broader applicability in next-generation transient,biodegradable,and flexible sensor technologies.
文摘将跟踪微分器加入到无模型自适应控制器中,结合跟踪微分器与无模型自适应控制器的优点,设计出一种适合于诸如非线性、时滞、时变、强耦合等复杂系统的控制器。该控制器利用跟踪微分器安排过渡过程,实现了对强干扰、大时滞系统的快速、无超调控制,并且进行了与非线性PID(proportional integral derivative)控制器的对比仿真研究。仿真结果表明:带有跟踪微分器的无模型自适应控制器具有的优点,适合于处理带有强干扰以及时滞系统的控制问题。
