Vibration Control of a High-Rise Building Structure:Theory and Experiment

In this study,an innovative solution is developed for vibration suppression of the high-rise building.The infinite dimensional system model has been presented for describing high-rise building structures which have a large inertial load with the help of the Hamilton’s principle.On the basis of this system model and with the use of the Lyapunov’s direct method,a boundary controller is proposed and the closed-loop system is uniformly bounded in the time domain.Finally,by using the Smart Structure laboratory platform which is produced by Quancer,we conduct a set of experiments and find that the designed method is resultful.

A Bio-Inspired Flapping-Wing Robot With Cambered Wings and Its Application in Autonomous Airdrop

Flapping-wing flight, as the distinctive flight method retained by natural flying creatures, contains profound aerodynamic principles and brings great inspirations and encouragements to drone developers. Though some ingenious flapping-wing robots have been designed during the past two decades, development and application of autonomous flapping-wing robots are less successful and still require further research. Here, we report the development of a servo-driven bird-like flapping-wing robot named USTBird-I and its application in autonomous airdrop.Inspired by birds, a camber structure and a dihedral angle adjustment mechanism are introduced into the airfoil design and motion control of the wings, respectively. Computational fluid dynamics simulations and actual flight tests show that this bionic design can significantly improve the gliding performance of the robot, which is beneficial to the execution of the airdrop mission.Finally, a vision-based airdrop experiment has been successfully implemented on USTBird-I, which is the first demonstration of a bird-like flapping-wing robot conducting an outdoor airdrop mission.

Hydrocortisone,vitamin C,and thiamine may not improve the outcome of patients with sepsis or septic shock:a systematic review and meta-analysis

Background This study aimed to conduct a systematic review and meta-analysis of the efficacy of hydrocortisone,vitamin C,and thiamine(HVT)in patients with sepsis or septic shock.Methods A literature search was performed in PubMed,Embase,Cochrane Library,and Web of Science from their inception to April 2021.Search terms included hydrocortisone,thiamine,vitamin C,sepsis,and septic shock.Only randomized controlled trials on HVT in treating sepsis and septic shock were analyzed.Risk ratio(RR)was generated using Review Manager 5.3 to evaluate binary variants,whereas mean±standard deviation(MD)was generated to assess continuous variants.Results A total of 7 randomized controlled trials,with 1233 patients,were included in this meta-analysis.There was no significant difference in long-term mortality(35.3%vs 33.2%;RR:1.07;95%confidence interval[95%CI]:0.90-1.27;P=0.45;I^(2)=0%),intensive care unit(ICU)mortality(17.4%vs 17.5%;RR:0.99;95%CI:0.75-1.30;P=0.95;I^(2)=0%),in-hospital mortality(27.4%vs 25.8%;RR:1.06;95%CI:0.84-1.34;P=0.63;I^(2)=0%),and acute kidney injury morbidity(RR:1.04;95%CI:0.91-1.18;P=0.60;I^(2)=0%)between HVT and control groups.For continuous variables,there was no significant effect of HVT therapy on delta Sequential Organ Failure Assessment(△SOFA)score(MD:−0.44;95%CI:−1.00 to 0.12;P=0.12;I^(2)=49%),length of ICU stay(MD:0.43;95%CI:−0.27 to 1.14;P=0.23;I^(2)=0%),and length of hospital stay(MD:0.80;95%CI:−0.38 to 1.97;P=0.18;I^(2)=0%).Only vasopressor duration was significantly reduced in the HVT group(MD:−17.75;95%CI:−25.56 to−9.94;P<0.00001;I^(2)=38%).Vasopressor duration refers to the time to shock reversal.Alternatively,it is the amount of time(in hours)required for patients to withdraw all vasoactive medication support.Neither HVT nor control△SOFA reached statistical significance.Conclusion Hydrocortisone,vitamin C,and thiamine use was not associated with improved mortality,lower acute kidney injury incidence,lower△SOFA,and shorter ICU and in-hospital stays among patients with sepsis and septic shock.However,the use of vasopressors decreased significantly.Further direct head-to-head studies are needed.

仿猎鹰扑翼飞行器自主飞行控制系统设计

仿生扑翼飞行器作为一种新型的飞行器,具有噪声小、隐蔽性好、机动性强、能量利用效率高等优势,在民用和军用领域具有广阔的应用前景.仿生扑翼飞行器的自主飞行能力是高效执行飞行任务的关键.目前,国内外飞行器的自主飞行研究已经取得了一些成果,然而鲜有以仿生扑翼飞行器为载体的研究.仿生扑翼飞行器特有的驱动结构给自主飞行控制研究带来了较大的挑战.本文以仿猎鹰扑翼飞行器作为研究平台设计了自主飞行控制系统.由于仿猎鹰扑翼飞行器的负载较小,本文采用了重量较轻的STM32微型计算平台作为主控芯片设计了硬件系统.由于微型计算平台的算力有限,本文综合考虑制导精度和运算速度,提出了一种线性/非线性切换制导算法,并通过仿真实验与线性制导、非线性制导算法进行了对比,证明了其更加适合于仿猎鹰扑翼飞行器.考虑到仿猎鹰扑翼飞行器的机构滞后问题,对其滚转角和高度设计了一个串级PID控制器.结合面向仿猎鹰扑翼飞行器的地面站软件,最终实现了基于仿猎鹰扑翼飞行器的自主定高圆弧轨迹跟踪任务.