摘要：Inspired that the neck structure can stabilize the head from body movements and external dynamic vibration by the role of intervertebral disc and surrounding muscles,a novel multi-layer structure with nonlinear elastic components is proposed in this *** proposed structure is expected for loading the weight of the end effector and isolating bending vibration with lowfrequency in the range of 0.1 Hz to 1 ***,considering the loading,the potential energy,restoring force,and structural configuration in axial direction are ***,the dynamical restoring force and stiffness for bending are modelled for different structural parameters and configurations after the axial *** to the functions of the proposed structure required in applications including loading capacity and bending vibration isolation effectiveness,design criteria are carried *** to the realization of high-order quasi-zero stiffness property,the effective isolation band for bending vibration can be extended from about 0.08 *** addition,based on the proposed design criteria,the constructed multi-layer structure displays remarkable dynamical stabilization effectiveness in ultralow frequency *** proposed structure not only provides the biological explanations for car sickness,nausea,and airsickness of humans,but also solves the bottleneck techniques in bioinspired nonlinear isolation structural design for transverse dynamical stabilization,which has remarkable potential applications in the fields of mechanical arm,sensors in satellite etc.

摘要：This paper presented a control design methodology for a proton exchange membrane fuel cell (PEMFC) generation system for residential applications. The dynamic behavior of the generation system is complex in such applications. A comprehensive control design is very important for achieving a steady system operation and efficiency. The control strategy for a 60 kW generation system was proposed and tested based on the system dynamic model. A two-variable single neuron proportional-integral (PI) decoupling controller was developed for anode pressure and humidity by adjusting the hydrogen flow and water injection. A similar controller was developed for cathode pressure and humidity by adjusting the exhaust flow and water injection. The desired oxygen excess ratio was kept by a feedback controller based on the load current. An optimal seeking controller was used to trace the unique optimal power point. Two negative feedback controllers were used to provide AC power and a suitable voltage for residential loads by a power conditioning unit. Control simulation tests showed that 60 kW PEMFC generation system responded well for computer-simulated step changes in the load power demand. This control methodology for a 60 kW PEMFC generation system would be a competitive solution for system level designs such as parameter design, performance analysis, and online optimization.

摘要：A harmonic vortex beam is a typical vector beam with a helical wavefront at harmonic frequencies(e.g.,second and third harmonics). It provides an additional degree of freedom beyond spin-and orbitalangular momentum, which may greatly increase the capacity for communicating and encoding information. However, conventional harmonic vortex beam generators suffer from complex designs and a low nonlinear conversion efficiency. Here, we propose and experimentally demonstrate the generation of a large second-harmonic(SH) vortex beam with quasi-nonlinear spin–orbit interaction(SOI). Highquality SH vortex beams with large topological charges up to 28 are realized experimentally. This indicated that the quasi-angular-momentum of a plasmonic spiral phase plate at the excitation wavelength(topological charge, q) could be imprinted on the harmonic signals from the attached WS2 monolayer. The generated harmonic vortex beam has a topological charge of l_(n)= 2 nq(n is the harmonic order). The results may open new avenues for generating harmonic optical vortices for optical communications and enables novel multi-functional hybrid metasurface devices to manipulate harmonic beams.