Synthetic aperture imaging ladar （SAIL） has the capabil- ity of getting high-resolution and two-dimensional （2D）active imaging at a large distance in the side-looking mode, which has become an interesting area of ...Synthetic aperture imaging ladar （SAIL） has the capabil- ity of getting high-resolution and two-dimensional （2D）active imaging at a large distance in the side-looking mode, which has become an interesting area of research.展开更多
<strong>Background: </strong>Walking speed is a reliable barometer of adverse health outcomes, particularly among older people. Few studies evaluated factors associated with daily actual walking speed, rat...<strong>Background: </strong>Walking speed is a reliable barometer of adverse health outcomes, particularly among older people. Few studies evaluated factors associated with daily actual walking speed, rather than that measured in a laboratory setting or self-reported data.<strong> Methods: </strong>In a joint effort with The Pokémon Company, we recruited study participants through a women’s magazine and analyzed data from 63 Pokémon GO players. We measured the true walking speed in daily life among older women using a data-gathering mobile application. Then, using questionnaire survey data collected on these participants in 2019, we estimated the relationship between walking speed and their lifestyle and physiological factors. In the analysis, we employed a bi-directional stepwise linear regression approach, with the Akaike information criterion (AIC) for variable selection. <strong>Results: </strong>The mean age of the 63 participants was 63.03 years (standard deviation, SD 7.46);the average walking speed was 4.56 km per hour (SD 1.54);and 52 (82.5%) and 55 (87.3%) participants answered that they had excellent/good health physically and mentally, respectively. After adjusted for covariates in a stepwise regression approach, we identified a significant association between <span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1.33 (95% confidence intervals <span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>2.52 to <span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>0.15) km/hour lower walking speed and the experience of outdoor falls within a year. We also demonstrated that the walking speed was 1.07 (0.33 to 1.81) km/hour faster for those who had played Pokémon GO before the study started. <strong>Conclusions:</strong> The true walking speed in daily life among older women was measured by a data-gathering mobile application. Although all participants were women recruited on a voluntary basis with an understanding of the purpose of the study, and the surveys were conducted at a cross-sectional setting, a significant relationship with the experience of outdoor falls was demonstrated. We also present evidence suggesting a possible relationship between Pokémon GO play and faster walking speed.展开更多
有限元(Finite Element,FE)模型的正确性和可靠性对于确保结构仿真达到其分析目的相当重要。文章介绍了空调室外机(Outdoor Unit of Conditioner,OUC)有限元模型的建模技术与模型更新。建构OUC的有限元模型必须呈现结构的物理特性,包括...有限元(Finite Element,FE)模型的正确性和可靠性对于确保结构仿真达到其分析目的相当重要。文章介绍了空调室外机(Outdoor Unit of Conditioner,OUC)有限元模型的建模技术与模型更新。建构OUC的有限元模型必须呈现结构的物理特性,包括几何形状、材料性质、接触接口和边界条件等,并施以实验进行验证。一般的方法是对结构进行实验模态分析(ExperimentalModalAnalysis,EMA)以获得结构模态参数。同时,也可由有限元模型的数值分析求得理论模态参数。模型更新是调整有限元模型参数,使分析模型和实际结构的结构模态特性相符。结果显示,更新后的有限元模型在结构模态和频率域特性上,能充分呈现空调室外机实际结构的振动特性。展开更多
Flapping-wing flying robots(FWFRs),especially large-scale robots,have unique advantages in flight efficiency,load capacity,and bionic hiding.Therefore,they have significant potential in environmental detection,disaste...Flapping-wing flying robots(FWFRs),especially large-scale robots,have unique advantages in flight efficiency,load capacity,and bionic hiding.Therefore,they have significant potential in environmental detection,disaster rescue,and anti-terrorism explosion monitoring.However,at present,most FWFRs are operated manually.Some have a certain autonomous ability limited to the cruise stage but not the complete flight cycle.These factors make an FWFR unable to give full play to the advantages of flapping-wing flight to perform autonomous flight tasks.This paper proposed an autonomous flight control method for FWFRs covering the complete process,including the takeoff,cruise,and landing stages.First,the flight characteristics of the mechanical structure of the robot are analyzed.Then,dedicated control strategies are designed following the different control requirements of the defined stages.Furthermore,a hybrid control law is presented by combining different control strategies and objectives.Finally,the proposed method and system are validated through outdoor flight experiments of the HIT-Hawk with a wingspan of 2.3 m,in which the control algorithm is integrated with an onboard embedded controller.The experimental results show that this robot can fly autonomously during the complete flight cycle.The mean value and root mean square(RMS)of the control error are less than 0.8409 and 3.054 m,respectively,when it flies around a circle in an annular area with a radius of 25 m and a width of 10 m.展开更多
基金supported by the National Natural Science Foundation of China(Nos.61605226 and 61505233)the Shanghai Astronomical Observatory,Chinese Academy of Sciences
文摘Synthetic aperture imaging ladar （SAIL） has the capabil- ity of getting high-resolution and two-dimensional （2D）active imaging at a large distance in the side-looking mode, which has become an interesting area of research.
文摘<strong>Background: </strong>Walking speed is a reliable barometer of adverse health outcomes, particularly among older people. Few studies evaluated factors associated with daily actual walking speed, rather than that measured in a laboratory setting or self-reported data.<strong> Methods: </strong>In a joint effort with The Pokémon Company, we recruited study participants through a women’s magazine and analyzed data from 63 Pokémon GO players. We measured the true walking speed in daily life among older women using a data-gathering mobile application. Then, using questionnaire survey data collected on these participants in 2019, we estimated the relationship between walking speed and their lifestyle and physiological factors. In the analysis, we employed a bi-directional stepwise linear regression approach, with the Akaike information criterion (AIC) for variable selection. <strong>Results: </strong>The mean age of the 63 participants was 63.03 years (standard deviation, SD 7.46);the average walking speed was 4.56 km per hour (SD 1.54);and 52 (82.5%) and 55 (87.3%) participants answered that they had excellent/good health physically and mentally, respectively. After adjusted for covariates in a stepwise regression approach, we identified a significant association between <span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1.33 (95% confidence intervals <span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>2.52 to <span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>0.15) km/hour lower walking speed and the experience of outdoor falls within a year. We also demonstrated that the walking speed was 1.07 (0.33 to 1.81) km/hour faster for those who had played Pokémon GO before the study started. <strong>Conclusions:</strong> The true walking speed in daily life among older women was measured by a data-gathering mobile application. Although all participants were women recruited on a voluntary basis with an understanding of the purpose of the study, and the surveys were conducted at a cross-sectional setting, a significant relationship with the experience of outdoor falls was demonstrated. We also present evidence suggesting a possible relationship between Pokémon GO play and faster walking speed.
文摘有限元(Finite Element,FE)模型的正确性和可靠性对于确保结构仿真达到其分析目的相当重要。文章介绍了空调室外机(Outdoor Unit of Conditioner,OUC)有限元模型的建模技术与模型更新。建构OUC的有限元模型必须呈现结构的物理特性,包括几何形状、材料性质、接触接口和边界条件等,并施以实验进行验证。一般的方法是对结构进行实验模态分析(ExperimentalModalAnalysis,EMA)以获得结构模态参数。同时,也可由有限元模型的数值分析求得理论模态参数。模型更新是调整有限元模型参数,使分析模型和实际结构的结构模态特性相符。结果显示,更新后的有限元模型在结构模态和频率域特性上,能充分呈现空调室外机实际结构的振动特性。
基金supported by the National Natural Science Foundation of China(Grant No.62233001)the Program of Shenzhen Peacock Innovation Team(Grant No.KQTD20210811090146075)Shenzhen Excellent Scientific and Technological Innovation Talent Training Project(Grant No.RCJC20200714114436040)。
文摘Flapping-wing flying robots(FWFRs),especially large-scale robots,have unique advantages in flight efficiency,load capacity,and bionic hiding.Therefore,they have significant potential in environmental detection,disaster rescue,and anti-terrorism explosion monitoring.However,at present,most FWFRs are operated manually.Some have a certain autonomous ability limited to the cruise stage but not the complete flight cycle.These factors make an FWFR unable to give full play to the advantages of flapping-wing flight to perform autonomous flight tasks.This paper proposed an autonomous flight control method for FWFRs covering the complete process,including the takeoff,cruise,and landing stages.First,the flight characteristics of the mechanical structure of the robot are analyzed.Then,dedicated control strategies are designed following the different control requirements of the defined stages.Furthermore,a hybrid control law is presented by combining different control strategies and objectives.Finally,the proposed method and system are validated through outdoor flight experiments of the HIT-Hawk with a wingspan of 2.3 m,in which the control algorithm is integrated with an onboard embedded controller.The experimental results show that this robot can fly autonomously during the complete flight cycle.The mean value and root mean square(RMS)of the control error are less than 0.8409 and 3.054 m,respectively,when it flies around a circle in an annular area with a radius of 25 m and a width of 10 m.
