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Effect of Tai Chi on Cardiac and static Pulmonary Function in Older Community-Dwelling Adults at Risk of Ischemic Stroke: A Randomized Controlled Trial

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Chinese Journal of Integrative Medicine 2019年第8期25卷 582-589页

作者： ZHENG Guo-hua ZHENG Xin LI Jun-zhe DUAN Ting-jin TAO Jing CHEN Li-dian College of Nursing and Health Management Shanghai University of Medicine and Health Sciences Shanghai (201318) China College of Rehabilitation Medicine Fujian University of Traditional Chinese Medicine Fuzhou (350122)China Department of Physical Education Fujian University of Traditional Chinese Medicine Fuzhou (350122)China Fujian Key Laboratory of Rehabilitati on Tech no logy Fujia n Un iversity of Traditional Chinese Medicine Fuzhou (350122)China Collaborative Inno vation Cen ter for Rehabilitati on Tech no logy Fujian University of Traditional Chinese Medicine Fuzhou (350122)China

Objective: To evaluate the effect of tai chi exercise on cardiac and static lung function for older community-dwelling adults at risk of ischemic stroke. Methods: A total of 170 older community-dwelling adults (aged 55–75 years old) at risk of ischemic stroke were allocated to either tai chi training group (85 cases, five 60-min sessions of tai chi training per week for 12 weeks) or control group (85 cases, usual pbysical activity for 12 weeks) using a computer-generated randomization. The echocardiographic parameters of cardiac structure, cardiac function and static lung function were measured at baseline, after 12 weeks of intervention and additional 12-week follow-up period by a blinded professional staff member using a color Doppler ultrasound imaging device or a cardiopulmonary function instrument. The t test and linear mixed model based on the intention-to-treat analysis principle was used to calculate the effect. The adverse effect was observed. Results: Most of echocardiographic parameters on the cardiac structure, cardiac function and static lung function between the tai chi group and control group did not have a significant difference either post 12-week intervention or additional 12-week follow-up period. Only three parameters involving in right ventricular diameter (P=0.024), main pulmonary artery diameter (P=0.002) and vital capacity maximum (P=0.036) were beneficial to be improved in the tai chi group compared to the control group by the analysis of mixed linear model. No adverse effects were found during the intervention period. Conclusions: The 12-week tai chi exercise did not have an obvious beneficial effect on cardiac structure, cardiac function and static lung function in older community-dwelling adults at risk of ischemic stroke.(Trial registration No. ChiCTR-TRC-13003601)

关键词： tai chi cardiac structure and function static lung function ischemic stroke randomized controlled trial

Performance analysis of multi-GNSS static and RTK techniques in estimating height differences

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International Journal of Digital Earth 2020年第5期13卷 586-601页

作者： Ahmed Elaksher Tarig Ali Franck Kamtchang Christian Wegmann Adalberto Guerrero College of Engineering New Mexico State UniversityLas CrucesNew MexicoUSA Department of Civil Engineering College of EngineeringAmerican University of SharjahSharjahUAE Geomatics Engineering Lassonde School of EngineeringYork UniversityTorontoCanada Surveying Engineering Program College of EngineeringNew Mexico State UniversityLas CrucesNew MexicoUSA

Establishing reliable elevation differences is imperative for most geoscience and engineering applications.This work has traditionally been accomplished through spirit leveling techniques;however,surveyors have been utilizing satellite positioning systems in measuring height differences for more than a decade.Yet the quality of these heights needs to be evaluated in order to adopt them in different applications.In this article,we present the outcome of an accuracy assessment of height differences obtained with static and RTK surveys.Twenty control points with an average baseline length of 1 km were occupied with dual-frequency GNSS receivers for different time periods.Collected signals were processed using open-source software and verified with an online processing tool.Heights were estimated by processing the GPS and the GLONASS data individually,and combined(i.e.GNSS).Height differences were determined and compared with those measured by spirit levels and corrected through geoid models.Best results were achieved by combining GPS and GLONASS solutions for both static and RTK surveys.Solutions with either GPS or GLONASS satellites were comparable,but in most cases,the GPS solutions performed better.For the static surveys,longer occupation provided much accurate height differences.Inconsistencies among 10 different RTK surveys were minimum for the GPS+GLONASS solutions and worst for the GLONASS solutions.The ANOVA,LSD,F,and χ^(2) statistical tests confirmed our findings at the 95%confidence level.

关键词： GNSS static RTK multipath height differences

Influence of delta phase precipitation on static recrystallization of cold-rolled Inconel 718 alloy in solid solution treatment

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Journal of Iron and Steel Research(International) 2019年第2期26卷 148-153页

作者： Neng-yong Ye Ming Cheng Shl-hong Zhang Hong-wu Song Hong-wei Zhou Institute of Metal Research Chinese Academy of SciencesShenyang 110016LiaoningChina School of Mechanical Engineering Taizhou UniversityTaizhou 318013ZhejiangChina State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of TechnologyLanzhou 730050GansuChina

Due to the improvement in fatigue strength of cold-rolled blades,the static recrystallization behavior of cold-rolled Inconel 718 alloy in the solid solution treatment was investigated with the methods of optical microscopy and electron backscattered diffraction.The effect ofδphase precipitation on the static recrystallization process was also analyzed.The results show thatδphase preferentially precipitates comparing to static recrystallization.Affecting by theδphase preferential precipitation process,sub-grain migration is the main nucleation mechanism in the static recrystallization of coldrolled Inconel 718 alloy at 980°C.Meanwhile,strain-induced boundary migration also exists as an aided nucleation mechanism when the rolling reduction is less than 30%.

关键词： Cold rolling Inconel 718 alloy static recrystallization δphase precipitation

A novel static shape-adjustment technique for planar phased-array satellite antennas

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Acta Mechanica Sinica 2018年第6期34卷 1145-1155页

作者： Ji-Yang Zhou Guang-Yu Lu Guo-Ping Cai Guang-Qiang Fang Liang-Liang Lv Jun-Wei Shi Department of Engineering Mechanics State Key Laboratory of Ocean EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai Institute of Aerospace System Engineering Shanghai 201109China

Planar phased-array satellite antennas deform when subjected to external disturbances such as thermal gradients or slewing maneuvers.Such distortion can degrade the coherence of the antenna and must therefore be eliminated to maintain performance.To support planar phased-array satellite antennas,a truss with diagonal cables is often applied,generally pretensioned to improve the stiffness of the antenna and maintain the integrity of the structure.A new technique is proposed herein,using the diagonal cables as the actuators for static shape adjustment of the planar phased-array satellite antenna.In this technique,the diagonal cables are not pretensioned;instead,they are slack when the deformation of the antenna is small.When using this technique,there is no need to add redundant control devices,improving the reliability and reducing the mass of the antenna.The finite element method is used to establish a structural model for the satellite antenna,then a method is introduced to select proper diagonal cables and determine the corresponding forces.Numerical simulations of a simplified two-bay satellite antenna are first carried out to validate the proposed technique.Then,a simplified 18-bay antenna is also studied,because spaceborne satellite antennas have inevitably tended to be large in recent years.The numerical simulation results show that the proposed technique can be effectively used to adjust the static shape of planar phased-array satellite antennas,achieving high precision.

关键词： Planar phased-array satellite antenna static shape adjustment Diagonal cables Active control

Three dimensional dendritic morphology and orientation transition induced by high static magnetic field in directionally solidified Al-10wt.%Zn alloy

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Journal of Materials Science & Technology 2019年第8期35卷 1587-1592页

作者： Sansan Shuai Xin Lin Yuanhao Dong Long Hou Hanlin Liao Jiang Wang Zhongming Ren State Key Laboratory of Advanced Special Steel School of Materials Science and EngineeringShanghai UniversityShanghai 200444 China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072 China Université de Technologie de Belfort-Montbéliard LERMPS Site de Sévenans90010 Belfort Cedex France

Effect of high static magnetic field on the dendritic morphology and growth direction in directionally solidified Al-10 wt.%Zn alloy were studied by three-dimensional(3D) X-ray micro-computed tomography, Electron Back-scattered Diffraction(EBSD) and X-ray Diffraction(XRD). The application of high static axial magnetic field(5T) during directional solidification was found to destabilize the solid/liquid interface and cause the growth direction of dendrite deviate from thermal gradient, leading to irregular solid/liquid interfacial shape and cellular to dendritic morphology transition. The thermoelectric magnetic convection(TEMC) caused by the interaction of thermoelectric effect and magnetic field was supposed to be responsible for the transition. In addition, the EBSD and XRD results confirm that the preferred growth direction of α-Al was found to transform from the traditionally expected to. The dendrite orientation transition(DOT) in Al-10 wt.%Zn alloy can be attributed to the effect of applied magnetic field on the anisotropy of crystal during solidification. The result indicates the potential application of high static magnetic field in altering the morphology and preferred growth direction of dendrite during directional solidification.

关键词： Al-Zn alloy High static magnetic field Three-dimensional dendrite morphology Dendrite orientation transition X-ray computed tomography

Research on static bearing characteristics of magnetic-liquid double suspension bearing

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High Technology Letters 2019年第4期25卷 434-442页

作者：赵建华 Wang Qiang Zhang Bin Chen Tao Gao Dianrong ebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan UniversityQinhuangdao 066004P.R.China Jiangsu Provincial Key Laboratory of Advanced Manufacture and Process for Marine Mechanical Equipment Zhenjiang 212003P.R.China

Due to low viscosity of seawater,it is difficult to form a seawater-lubricated film.It is easy to cause the overload and burning phenomenon of seawater-lubrication sliding bearing,and then the operation stability and service life can be shortened seriously.Therefore,the paper introduces an electromagnetic suspension theory into the seawater lubricated sliding bearing.Then a novel magnetic-liquid double suspension bearing can be formed,which can enhance bearing capacity and stiffness greatly.Firstly,the structural characteristics,support-adjustment mechanism of magnetic-liquid double suspension bearing is analyzed.Secondly,based on force balance equation,electromagnetic equation and flow equation,the transfer functions of single DOF bearing system of magnetic-liquid double suspension bearing under constant-flow supply model are deduced.Then bearing capacity,static stiffness and total power loss are selected as static performance indexes.The influence rule of operaton and structural parameters on the static performance of single DOF bearing system will be analyzed.The results show that bearing capacity decreases with the increase of liquid film thickness and width of edge seals,bias current and coil turns decrease.static stiffness decreases with the increase of liquid film thickness,edge seals width,bias current and coil turns.Total power loss decreases with the increase of liquid film thickness,edge seals width,bias current and coil turns decrease.And static performance indexes can not be affected by liquid viscosity.The proposed research provides some theoretical and experimental basis for the parameter design of magnetic-liquid double suspension bearing.

关键词： magnetic-liquid double suspension bearing static performance index bearing capacity static stiffness total power loss

Model of Underground Ant Nest Structure Using static and Dynamic Finite Element Analysis

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Acta Mechanica Solida Sinica 2018年第6期31卷 717-730页

作者： Wenjun Qu Wei Zhou Peng Zhu Zhi Zhang Department of Structural Engineering Tongji University Shanghai 200092 China The High School Affiliated with Shanghai University Shanghai 200444 Chinch

This paper focuses on the structural characteristics of ant nests,which are complex structures.Natural underground ant nests generally have good air circulation,pressure resistance, waterproof properties,thermal insulation and a favorable temperature and relative humidity. Additionally,ant nests are often surrounded by trees and other natural barriers.In this study, the natural underground ant nests of Iridomyrmex anceps were gathered from different collection sites.Manual cutting and frozen computer numerical control milling were performed on the ant nests in a laboratory.The internal structure of each nest was measured and recorded,and then, the 2D and 3D numerical structure models of the Iridomyrmex anceps nest were created.The static and dynamic simulation analysis of an underground ant nest structure was performed by using finite element analysis software (ABAQUS),and the mechanical properties of the ant nest were discussed.The underground ant nest structure effectively resisted the additional stress due to external static and live loads,and the ant nest was not completely destroyed.

关键词： Underground ant nest Iridomyrmex anceps Frozen CNC milling Finite element analysis static simulation Dynamic simulation

Three-Dimensional static Analysis of Nanoplates and Graphene Sheets by Using Eringen’s Nonlocal Elasticity Theory and the Perturbation Method

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Computers, Materials & Continua 2016年第5期52卷 73-103页

作者： Chih-Ping Wu Wei-Chen Li Department of Civil Engineering National Cheng Kung UniversityTainan 70101TaiwanROC

A three-dimensional(3D)asymptotic theory is reformulated for the static analysis of simply-supported,isotropic and orthotropic single-layered nanoplates and graphene sheets(GSs),in which Eringen’s nonlocal elasticity theory is used to capture the small length scale effect on the static behaviors of these.The perturbation method is used to expand the 3D nonlocal elasticity problems as a series of two-dimensional(2D)nonlocal plate problems,the governing equations of which for various order problems retain the same differential operators as those of the nonlocal classical plate theory(CST),although with different nonhomogeneous terms.Expanding the primary field variables of each order as the double Fourier series functions in the in-plane directions,we can obtain the Navier solutions of the leading-order problem,and the higher-order modifications can then be determined in a hierarchic and consistent manner.Some benchmark solutions for the static analysis of isotropic and orthotropic nanoplates and GSs subjected to sinusoidally and uniformly distributed loads are given to demonstrate the performance of the 3D nonlocal asymptotic theory.

关键词： Eringen’s nonlocal elasticity theory graphene sheets nanoplates static the perturbation method three-dimensional nonlocal elasticity

A Low Power,High Sensitivity SiGe HBT static Frequency Divider up to 90 GHz for Millimeter-Wave Application

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China Communications 2019年第2期16卷 85-94页

作者： Peigen Zhou Jixin Chen Pinpin Yan Debin Hou Wei Hong State Key Laboratory of Millimeter Waves Southeast University

A layout and connection optimization for static frequency divider is presented. The layout optimization provides a new circle topology transistors placement and reasonable connection structure, which reduces the parasitic effectively and enables self-oscillation frequency enhancement. Besides, bandwidth enhancement techniques based on a center-tap capacitor in input balun design and inductive peaking in latch design are adopted to improve further high frequency performance with low power consumption. As a proof of concept, design of a divide-by-2 static frequency divider in 0.13 μm SiGe BiCMOS technology is reported. With single-ended input clock signal, the divider is measured to be operated from 40 to 90 GHz. Phase noise measurements of a 90 GHz input clock signal indicate ideal behavior with no measurable noise contribution from the divider. The divider followed by a buffer that can deliver more than-10 dBm output power, which is sufficient to drive succeeding stage. To the author's knowledge, the divider exhibits a competitive power dissipation and the highest FOM among silicon based frequency dividers that operating higher than 70 GHz.

关键词： E-band layout optimization millimeter wave integrated circuits static frequency divider SiGe