AIM: To estimate the prevalence and risk factors for vitreous floaters in the general population. ·METHODS: An electronic survey was administered through a smartphone app asking various demographic and health que...AIM: To estimate the prevalence and risk factors for vitreous floaters in the general population. ·METHODS: An electronic survey was administered through a smartphone app asking various demographic and health questions, including whether users experience floaters in their field of vision. Multivariate logistic regression analysis was used to determine risk factors. ·RESULTS: A total of 603 individuals completed the survey, with 76% reporting that they see floaters, and 33% reporting that floaters caused noticeable impairment in vision. Myopes were 3.5 times more likely (P =0.0004), and hyperopes 4.4 times more likely (P =0.0069) to report moderate to severe floaters compared to those with normal vision. Floater prevalence was not significantly affected by respondent age, race, gender, and eye color. ·CONCLUSION: Vitreous floaters were found to be a very common phenomenon in this non -clinical general population sample, and more likely to be impairing in myopes and hyperopes.展开更多
Vertical axis wind turbines(VAWTs) are advantageous for the development of large-scale offshore wind power because the drive system is located at the bottom of the turbine. This study investigates the structural stren...Vertical axis wind turbines(VAWTs) are advantageous for the development of large-scale offshore wind power because the drive system is located at the bottom of the turbine. This study investigates the structural strength of a tri-floater floating foundation supporting a 2.6 MW Darrieus VAWT. Finite element models of the floating foundation were developed using space plate-beam elements. The environmental loads, such as the aerodynamic loads, static wind loads, and wave-current loads, were considered. The general strengths of the floating foundation were calculated for the normal operating case(a cut-out wind speed of 25 m s^(-1) and blade rotation of 12 r min^(-1) were used to analyze the most unfavorable loads) and an extreme case(wind speed of 40 m s^(-1) and parked blades), and the weak components of the structure were analyzed. The results show that the floating foundation meets the strength requirements and the structural stress is highest when the wave, wind, and current are in a collinear direction. The main and secondary supporting bars transmit the loads between the stand columns and the tower foundation, and their stresses are higher than those in the other components. In the actual design, these supporting bars should be strengthened. The aerodynamic loads are very important and should be considered in the structural strength analysis of the floating foundation and the floating wind turbine system.展开更多
AIM:To investigate the depressive state among the patients with symptomatic vitreous floaters(SVF),as well as its change after SVF removal via vitrectomy surgery.METHODS:Twenty-eight eyes of 28 patients who underwent ...AIM:To investigate the depressive state among the patients with symptomatic vitreous floaters(SVF),as well as its change after SVF removal via vitrectomy surgery.METHODS:Twenty-eight eyes of 28 patients who underwent 27-gauge pars plana vitrectomy(PPV)for SVF were included.Thirty-nine eyes of 39 age-and gendermatched healthy volunteers without SVF were also recruited as a healthy control.Center for Epidemiologic Studies Depression(CES-D)was used to assess volunteers and patients’depression(before and 1 wk after PPV).RESULTS:The CES-D score was 18.3±8.6 for patients,and was 12.4±6.0 for healthy control(P=0.003).Patients were significantly more likely to be in a depressive state(53.6%,defined as CES-D score≥16)than the healthy control(20.5%,P=0.005).For patients with SVF,the CES-D score was negatively correlated with their age(rs=-0.42,P=0.025).After PPV,both the CES-D score(11.9±5.4 vs 18.3±8.6,P<0.001)and proportion of depressive state(18.5%vs 53.6%,P=0.005)were significantly decreased.CONCLUSION:This study suggests that symptoms of vitreous floaters have an apparently negative impact on patients’psychological state.The PPV can effectively relieve the depressive state for patients with SVF.展开更多
There are increasing focuses on developing cost-effective floating wind turbines,for which efficient stress analysis methods are needed for floater structural design.Most of the today’s studies focus on global analys...There are increasing focuses on developing cost-effective floating wind turbines,for which efficient stress analysis methods are needed for floater structural design.Most of the today’s studies focus on global analysis methods in which the floater is assumed as a rigid body or multiple rigid bodies and the stress distributions in the floater cannot be directly obtained.As part of the COWI Fonden funded EMULF project,a summary about the methodology,the numerical modeling procedure and the verification for stress response analysis of a semi-submersible floater for a 15MW wind turbine is presented.This analy-sis procedure includes the regeneration of the hydrodynamic pressure loads on the external wet surface of the floater due to wave diffraction,radiation and hydrostatic pressure change,and the application of these pressure loads,together with the time-varying gravity due motions,the inertial loads and the forces/moments at the boundaries(i.e.tower bottom and mooring line fairleads)of the floater to obtain the deformation and the stresses of the floater in the time domain.The analysis procedure is imple-mented in a developed MATLAB code and the DNV software package.The importance of the different hydrodynamic pressure components was discussed considering representative sea states.A verification of the obtained stress time series and statistics using this method against the regeneration from a linear frequency-domain approach was made considering irregular wave actions only,and a very good agree-ment was obtained.The developed methodology can provide an efficient solution for structural design analysis of floating wind turbines.展开更多
文摘AIM: To estimate the prevalence and risk factors for vitreous floaters in the general population. ·METHODS: An electronic survey was administered through a smartphone app asking various demographic and health questions, including whether users experience floaters in their field of vision. Multivariate logistic regression analysis was used to determine risk factors. ·RESULTS: A total of 603 individuals completed the survey, with 76% reporting that they see floaters, and 33% reporting that floaters caused noticeable impairment in vision. Myopes were 3.5 times more likely (P =0.0004), and hyperopes 4.4 times more likely (P =0.0069) to report moderate to severe floaters compared to those with normal vision. Floater prevalence was not significantly affected by respondent age, race, gender, and eye color. ·CONCLUSION: Vitreous floaters were found to be a very common phenomenon in this non -clinical general population sample, and more likely to be impairing in myopes and hyperopes.
基金supported by the National Natural Science Foundation of China(No.51579176)the Natural Science Foundation of Tianjin(No.16JCYBJC21200)the Research Fund of the State Key Laboratory of Ocean Engineering,Shanghai Jiao Tong University(No.1501)
文摘Vertical axis wind turbines(VAWTs) are advantageous for the development of large-scale offshore wind power because the drive system is located at the bottom of the turbine. This study investigates the structural strength of a tri-floater floating foundation supporting a 2.6 MW Darrieus VAWT. Finite element models of the floating foundation were developed using space plate-beam elements. The environmental loads, such as the aerodynamic loads, static wind loads, and wave-current loads, were considered. The general strengths of the floating foundation were calculated for the normal operating case(a cut-out wind speed of 25 m s^(-1) and blade rotation of 12 r min^(-1) were used to analyze the most unfavorable loads) and an extreme case(wind speed of 40 m s^(-1) and parked blades), and the weak components of the structure were analyzed. The results show that the floating foundation meets the strength requirements and the structural stress is highest when the wave, wind, and current are in a collinear direction. The main and secondary supporting bars transmit the loads between the stand columns and the tower foundation, and their stresses are higher than those in the other components. In the actual design, these supporting bars should be strengthened. The aerodynamic loads are very important and should be considered in the structural strength analysis of the floating foundation and the floating wind turbine system.
基金Supported by Zhejiang Provincial Natural Science Foundation of China(No.LQ18H120004)the Innovation Research Project of the Eye Hospital of Wenzhou Medical University(No.YNCX201308).
文摘AIM:To investigate the depressive state among the patients with symptomatic vitreous floaters(SVF),as well as its change after SVF removal via vitrectomy surgery.METHODS:Twenty-eight eyes of 28 patients who underwent 27-gauge pars plana vitrectomy(PPV)for SVF were included.Thirty-nine eyes of 39 age-and gendermatched healthy volunteers without SVF were also recruited as a healthy control.Center for Epidemiologic Studies Depression(CES-D)was used to assess volunteers and patients’depression(before and 1 wk after PPV).RESULTS:The CES-D score was 18.3±8.6 for patients,and was 12.4±6.0 for healthy control(P=0.003).Patients were significantly more likely to be in a depressive state(53.6%,defined as CES-D score≥16)than the healthy control(20.5%,P=0.005).For patients with SVF,the CES-D score was negatively correlated with their age(rs=-0.42,P=0.025).After PPV,both the CES-D score(11.9±5.4 vs 18.3±8.6,P<0.001)and proportion of depressive state(18.5%vs 53.6%,P=0.005)were significantly decreased.CONCLUSION:This study suggests that symptoms of vitreous floaters have an apparently negative impact on patients’psychological state.The PPV can effectively relieve the depressive state for patients with SVF.
文摘There are increasing focuses on developing cost-effective floating wind turbines,for which efficient stress analysis methods are needed for floater structural design.Most of the today’s studies focus on global analysis methods in which the floater is assumed as a rigid body or multiple rigid bodies and the stress distributions in the floater cannot be directly obtained.As part of the COWI Fonden funded EMULF project,a summary about the methodology,the numerical modeling procedure and the verification for stress response analysis of a semi-submersible floater for a 15MW wind turbine is presented.This analy-sis procedure includes the regeneration of the hydrodynamic pressure loads on the external wet surface of the floater due to wave diffraction,radiation and hydrostatic pressure change,and the application of these pressure loads,together with the time-varying gravity due motions,the inertial loads and the forces/moments at the boundaries(i.e.tower bottom and mooring line fairleads)of the floater to obtain the deformation and the stresses of the floater in the time domain.The analysis procedure is imple-mented in a developed MATLAB code and the DNV software package.The importance of the different hydrodynamic pressure components was discussed considering representative sea states.A verification of the obtained stress time series and statistics using this method against the regeneration from a linear frequency-domain approach was made considering irregular wave actions only,and a very good agree-ment was obtained.The developed methodology can provide an efficient solution for structural design analysis of floating wind turbines.
