AIM:To explore the long-term efficacy,safety,and optical mechanism of orthokeratology with increased compression factor in adolescent myopia control.METHODS:A prospective,double-masked,and randomized clinical trial wa...AIM:To explore the long-term efficacy,safety,and optical mechanism of orthokeratology with increased compression factor in adolescent myopia control.METHODS:A prospective,double-masked,and randomized clinical trial was performed from May 2016 to June 2020.Subjects aged between 8 and 16y,with myopia(-5.00 to-1.00 D),low astigmatism(≥-1.50 D)and anisometropia(≤1.00 D),were stratified into low(-2.75 to-1.00 D)and moderate(-5.00 to-3.00 D)myopia groups.Then they were randomly assigned to wear either increased compression factor(ICF;1.75 D)orthokeratology or conventional compression factor(CCF;0.75 D)orthokeratology.The data were recorded including axial length(AL),spherical equivalent(SE),best corrected visual acuity(BCVA),near visual acuity(NVA),corneal staining(using Efron grading scales),corneal hysteresis(CH),corneal resistance factor(CRF),higher-order aberrations(HOAs,expressed as root mean square,RMS_(h)),and subfoveal choroidal thickness(SFCh T)in the 2-year followup period.Pearson's correlation coefficient was conducted to analyze the association between the changes in AL and RMS_(h),SFCh T.RESULTS:At the 2-year visit,there were no statistical differences in all the parameters between the ICF group and the CCF group in low myopia subjects(P>0.05).For the moderate myopia subjects,the ICF group had shorter AL elongation(0.23±0.08 vs 0.30±0.11 mm,P=0.015),higher RMS_(h)(1.94±0.50 vs 1.65±0.51μm,P=0.041),and higher SFCh T(279.04±35.72 vs 254.08±29.60μm,P=0.008)than those in CCF group.The change in AL was negatively correlated with RMS_(h)(r=-0.687,P<0.001)and SFCh T(r=-0.464,P=0.013).CONCLUSION:ICF orthokeratology can control the progression of moderate myopia more effectively,which might be related to greater RMS_(h) and SFCh T.展开更多
In order to describe the compressibility of traffic flows and determine the compression factors, the Mach number of gas dynamics is introduced, and the concept and the formula of the compression factor are obtained. A...In order to describe the compressibility of traffic flows and determine the compression factors, the Mach number of gas dynamics is introduced, and the concept and the formula of the compression factor are obtained. According to the concept of the compression factor and its differential equation, a stop-wave model is built. The theoretical value and the observed one are obtained by the survey data in Changchun city. The relative error between the two values is 20. 3%. The accuracy is improved 39% compared with the result from the traditional stop-wave model. The results show that the traffic flow is compressible, and the methods of research on gas compressibility is also applicable to the traffic flow. The stop-wave model obtained by the compression factor can better describe the phenomenon of the stop wave at a signalized intersection when compared with the traditional stop-wave model.展开更多
Due to the coupled motion between the rotor unmanned aerial vehicle(UAV)and the manipulator,the underactuation characteristics of the system itself,and the influence of external uncertainties,the stability of the roto...Due to the coupled motion between the rotor unmanned aerial vehicle(UAV)and the manipulator,the underactuation characteristics of the system itself,and the influence of external uncertainties,the stability of the rotor UAV’s manipulator control system is difficult to control.Based on the dynamic model of the rotor UAV,the stability of the whole UAV manipulator control system is improved by using the piecewise cost function,the compression factor particle swarm optimization(PSO)algorithm and the sliding mode PID to establish the sliding mode PID control stability method based on the PSO.Compared with the sliding mode PID control method,this method solves the serious buffeting problem in the sliding mode control,reduces the influence of the external disturbance and realizes the attitude stabilization control of the UAV manipulator quickly and accurately,thus shortens the system adjustment time and improves the anti-interference ability.展开更多
基金Supported by Education Department Foundation of Sichuan Province(No.15ZA0262)。
文摘AIM:To explore the long-term efficacy,safety,and optical mechanism of orthokeratology with increased compression factor in adolescent myopia control.METHODS:A prospective,double-masked,and randomized clinical trial was performed from May 2016 to June 2020.Subjects aged between 8 and 16y,with myopia(-5.00 to-1.00 D),low astigmatism(≥-1.50 D)and anisometropia(≤1.00 D),were stratified into low(-2.75 to-1.00 D)and moderate(-5.00 to-3.00 D)myopia groups.Then they were randomly assigned to wear either increased compression factor(ICF;1.75 D)orthokeratology or conventional compression factor(CCF;0.75 D)orthokeratology.The data were recorded including axial length(AL),spherical equivalent(SE),best corrected visual acuity(BCVA),near visual acuity(NVA),corneal staining(using Efron grading scales),corneal hysteresis(CH),corneal resistance factor(CRF),higher-order aberrations(HOAs,expressed as root mean square,RMS_(h)),and subfoveal choroidal thickness(SFCh T)in the 2-year followup period.Pearson's correlation coefficient was conducted to analyze the association between the changes in AL and RMS_(h),SFCh T.RESULTS:At the 2-year visit,there were no statistical differences in all the parameters between the ICF group and the CCF group in low myopia subjects(P>0.05).For the moderate myopia subjects,the ICF group had shorter AL elongation(0.23±0.08 vs 0.30±0.11 mm,P=0.015),higher RMS_(h)(1.94±0.50 vs 1.65±0.51μm,P=0.041),and higher SFCh T(279.04±35.72 vs 254.08±29.60μm,P=0.008)than those in CCF group.The change in AL was negatively correlated with RMS_(h)(r=-0.687,P<0.001)and SFCh T(r=-0.464,P=0.013).CONCLUSION:ICF orthokeratology can control the progression of moderate myopia more effectively,which might be related to greater RMS_(h) and SFCh T.
基金The National Basic Research Program of China (973Pro-gram)(No.2006CB705505)
文摘In order to describe the compressibility of traffic flows and determine the compression factors, the Mach number of gas dynamics is introduced, and the concept and the formula of the compression factor are obtained. According to the concept of the compression factor and its differential equation, a stop-wave model is built. The theoretical value and the observed one are obtained by the survey data in Changchun city. The relative error between the two values is 20. 3%. The accuracy is improved 39% compared with the result from the traditional stop-wave model. The results show that the traffic flow is compressible, and the methods of research on gas compressibility is also applicable to the traffic flow. The stop-wave model obtained by the compression factor can better describe the phenomenon of the stop wave at a signalized intersection when compared with the traditional stop-wave model.
基金This research is supported by the National Natural Science Foundation of China(51875293,51575283,61605083,51605232)Key points for marine environmental security(2018YFC1405700).
文摘Due to the coupled motion between the rotor unmanned aerial vehicle(UAV)and the manipulator,the underactuation characteristics of the system itself,and the influence of external uncertainties,the stability of the rotor UAV’s manipulator control system is difficult to control.Based on the dynamic model of the rotor UAV,the stability of the whole UAV manipulator control system is improved by using the piecewise cost function,the compression factor particle swarm optimization(PSO)algorithm and the sliding mode PID to establish the sliding mode PID control stability method based on the PSO.Compared with the sliding mode PID control method,this method solves the serious buffeting problem in the sliding mode control,reduces the influence of the external disturbance and realizes the attitude stabilization control of the UAV manipulator quickly and accurately,thus shortens the system adjustment time and improves the anti-interference ability.
