Asynchronous gain-scheduled control of deepwater drilling riser system with hybrid event-triggered sampling and unreliable communication

This paper investigates the recoil control of the deepwater drilling riser system with nonlinear tension force and energy-bounded friction force under the circumstances of limited network resources and unreliable communication.Different from the existing linearization modeling method,a triangle-based polytope modeling method is applied to the nonlinear riser system.Based on the polytope model,to improve resource utilization and accommodate random data loss and communication delay,an asynchronous gain-scheduled control strategy under a hybrid event-triggered scheme is proposed.An asynchronous linear parameter-varying system that blends input delay and impulsive update equation is presented to model the nonlinear networked recoil control system,where the asynchronous deviation bounds of scheduling parameters are calculated.Resorting to the Lyapunov-Krasovskii functional method,some solvable conditions of disturbance attenuation analysis and recoil control design are derived such that the resulting networked system is exponentially mean-square stable with prescribed H∞performance.The obtained numerical results verified that the proposed nonlinear networked control method can achieve a better recoil response of the riser system with less transmission data compared with the linear control method.

Ultrasound deep brain stimulation decelerates telomere shortening in Alzheimer’s disease and aging mice

Telomere length is a reliable biomarker for health and longevity prediction in both humans and animals.The common neuromodulation techniques,including deep brain stimulation(DBS)and optogenetics,have excellent spatial resolution and depth penetration but require implementation of electrodes or optical fibers.Therefore,it is important to develop methods for noninvasive modulation of telomere length.Herein,we reported on a new method for decelerating telomere shortening using noninvasive ultrasound deep brain stimulation(UDBS).Firstly,we found that UDBS could activate the telomerase-associated proteins in normal mice.Then,in the Alzheimer’s disease mice,UDBS was observed to decelerate telomere shortening of the cortex and myocardial tissue and to effectively improve spatial learning and memory abilities.Similarly,UDBS was found to significantly slow down telomere shortening of the cortex and peripheral blood,and improve motor and cognitive functions in aging mice.Finally,transcriptome analysis revealed that UDBS upregulated the neuroactive ligand-receptor interaction pathway.Overall,the present findings established the critical role of UDBS in delaying telomere shortening and indicated that ultrasound modulation of telomere length may constitute an effective therapeutic strategy for aging and aging-related diseases.