The performance of the three-dimensional differential geometric guidance law with proportional navigation formation against a target maneuvering arbitrarily with time-varying normal acceleration is thoroughly analyzed...The performance of the three-dimensional differential geometric guidance law with proportional navigation formation against a target maneuvering arbitrarily with time-varying normal acceleration is thoroughly analyzed using the Lyapunov-like approach.The validation of this guidance law is firstly proved,and then the performance issues such as capturability,heading error control efficiency,line of sight rate convergence,and commanded acceleration requirement are analyzed,under the condition that the missile is initially flying toward the target with a speed advantage.It is proved that an intercept can occur and the line of sight rate and missile commanded acceleration can be limited in certain ranges,if the initial heading error is small and the navigation gain is sufficiently large.The nonlinear relative dynamics between the missile and the target is taken into full account,and the analysis process is simple and intuitive,due to the use of a convenient line of sight rotating coordinate system.Finally,the new theoretical findings are validated by numerical simulations.展开更多
目的:研究超声引导下正中入路硬膜外分娩镇痛的临床效果。方法:选择2020年1月—2021年12月广州市花都区妇幼保健院收治的100例产妇作为研究对象,采用随机数表法,分为对照组(n=50)和研究组(n=50),分别给予硬膜外分娩镇痛和予以超声引导...目的:研究超声引导下正中入路硬膜外分娩镇痛的临床效果。方法:选择2020年1月—2021年12月广州市花都区妇幼保健院收治的100例产妇作为研究对象,采用随机数表法,分为对照组(n=50)和研究组(n=50),分别给予硬膜外分娩镇痛和予以超声引导下正中入路硬膜外分娩镇痛,对两组产妇产程时间、两组产妇分娩方式、两组产妇疼痛程度、两组产妇产后2 h出血量、两组新生儿1 min Apgar评分、两组产妇满意度、两组产妇不良反应进行观察比较。结果:研究组第一产程较对照组明显更长,第二产程时间较对照组明显更长,差异有统计学意义(t=2.758、8.653,P<0.05);研究组经阴分娩例数构成比较对照组明显更高,剖宫产分娩例数构成比较对照组明显更低,差异有统计学意义(χ^(2)=6.139、4.574,P<0.05);两组产妇宫口全开时观察比较结果显示以及分娩后观察比较结果显示研究组VAS评分均明显较对照组低,差异有统计学意义(t=17.455、8.384,P<0.05);两组产妇分娩满意度观察比较结果显示研究组评分明显较对照组高,差异有统计学意义(t=8.564,P<0.05)。结论:超声引导下正中入路硬膜外分娩镇痛虽然会在一定程度上延长产妇第一以及第二产程时间,但是可以进一步降低产妇剖宫产率,减轻产妇分娩疼痛,且对产后出血以及新生儿无不良影响,更有利于提高产妇分娩满意度。展开更多
基金This work was co-supported by the National Natural Science Foundation of China(Grant Nos.61690210 and 61690213)the National Basic Research Program of China(“973”Program,Grant No.2013CB733100).
文摘The performance of the three-dimensional differential geometric guidance law with proportional navigation formation against a target maneuvering arbitrarily with time-varying normal acceleration is thoroughly analyzed using the Lyapunov-like approach.The validation of this guidance law is firstly proved,and then the performance issues such as capturability,heading error control efficiency,line of sight rate convergence,and commanded acceleration requirement are analyzed,under the condition that the missile is initially flying toward the target with a speed advantage.It is proved that an intercept can occur and the line of sight rate and missile commanded acceleration can be limited in certain ranges,if the initial heading error is small and the navigation gain is sufficiently large.The nonlinear relative dynamics between the missile and the target is taken into full account,and the analysis process is simple and intuitive,due to the use of a convenient line of sight rotating coordinate system.Finally,the new theoretical findings are validated by numerical simulations.
文摘目的:研究超声引导下正中入路硬膜外分娩镇痛的临床效果。方法:选择2020年1月—2021年12月广州市花都区妇幼保健院收治的100例产妇作为研究对象,采用随机数表法,分为对照组(n=50)和研究组(n=50),分别给予硬膜外分娩镇痛和予以超声引导下正中入路硬膜外分娩镇痛,对两组产妇产程时间、两组产妇分娩方式、两组产妇疼痛程度、两组产妇产后2 h出血量、两组新生儿1 min Apgar评分、两组产妇满意度、两组产妇不良反应进行观察比较。结果:研究组第一产程较对照组明显更长,第二产程时间较对照组明显更长,差异有统计学意义(t=2.758、8.653,P<0.05);研究组经阴分娩例数构成比较对照组明显更高,剖宫产分娩例数构成比较对照组明显更低,差异有统计学意义(χ^(2)=6.139、4.574,P<0.05);两组产妇宫口全开时观察比较结果显示以及分娩后观察比较结果显示研究组VAS评分均明显较对照组低,差异有统计学意义(t=17.455、8.384,P<0.05);两组产妇分娩满意度观察比较结果显示研究组评分明显较对照组高,差异有统计学意义(t=8.564,P<0.05)。结论:超声引导下正中入路硬膜外分娩镇痛虽然会在一定程度上延长产妇第一以及第二产程时间,但是可以进一步降低产妇剖宫产率,减轻产妇分娩疼痛,且对产后出血以及新生儿无不良影响,更有利于提高产妇分娩满意度。
