Propagation of strong femtosecond hyper-Gaussian pulses in a cascade three-level molecular system is studied by solving numerically the Maxwell–Bloch equations by the iterative predictor-corrector finite-difference t...Propagation of strong femtosecond hyper-Gaussian pulses in a cascade three-level molecular system is studied by solving numerically the Maxwell–Bloch equations by the iterative predictor-corrector finite-difference time-domain method.Optical power limiting behavior induced by strong nonlinear two-photon absorption is observed for different orders of the femtosecond hyper-Gaussian pulses. Pulses of a higher order temporal profile are found to have a wider power range of optical limiting but a larger output saturation intensity. Both the output saturation value and the damage threshold of optical power limiting decrease with pulse duration increasing. The decrease of the pulse area along the pulse propagation is much slower than that obtained from the two-photon area theorem due to invalidity of the slowly varying amplitude approximation and the monochromatic field hypothesis.展开更多
Background and Purpose: Walking difficulties are defined as any reduction in speed, balance, or change of gait, causing limited ambulation. These difficulties are a common problem in older adults and may greatly affec...Background and Purpose: Walking difficulties are defined as any reduction in speed, balance, or change of gait, causing limited ambulation. These difficulties are a common problem in older adults and may greatly affect their quality of life (QOL) and restrict their personal independence and participation. This study aimed to determine the effect of intermittent pneumatic compression (IPC) on lower leg pain, walking capacity, functional mobility, ankle range of motion (AROM), and QOL of community-dwelling older people with walking difficulties. Methods: In this randomized controlled trial, 34 eligible participants with self-reported lower limb pain and limited ambulation were randomized either to the intermittent pneumatic compression intervention group (IPCIG) or static compression control group (SCCG). The IPCIG and SCCG were trained to receive IPC and SC respectively for both lower legs and instructed to continue the application independently at home for 15 minutes per session, 2 sessions a day, 7 days per week for 4 weeks independently at the home. Outcome measures of lower leg pain, AROM, walking capacity, and functional mobility were assessed at baseline and at the first, second, third, and fourth weeks after randomization. Quality of life was assessed at baseline and immediately after the intervention. Results and Discussion: IPCIG showed a more significant improvement compared to the SCCG at the post-interventional stage for QOL and all the subscales. The findings show that “80% improved QOL” is 53% higher with the application of IPC than with SC for 4 weeks. The IPCIG showed a more significant improvement in the 6-minute walk test (6 MWT) at the third and fourth weeks compared to the SCCG. A pairwise comparison of mean values of 6 MWT over 4 weeks within the IPCIG showed a significant difference between all the weeks. Pairwise comparisons between groups at each time point showed that the IPCIG showed a more significant improvement in the timed up and go (TUG) test at the third and fourth weeks compared to the SCCG. Pairwise comparison of mean values of TUG test within the IPCIG showed a significant difference over 4 weeks, except between the second and third weeks, fourth week, and third and fourth weeks. The IPCIG showed a more significant improvement in lower leg pain between all weeks except the first week compared to the SCCG. Pairwise comparison of mean values of lower leg pain over 4 weeks within the IPCIG showed a significant difference among all weekly outcomes except between 1 and 2 weeks. The IPCIG showed a more significant improvement in left and right ankle dorsiflexion ROM at the third and fourth weeks compared to the SCCG. Conclusions: The IPC was effective in reducing lower leg pain and increasing the AROM and improving the walking capacity, functional mobility level, and QOL of community-dwelling older people with walking disabilities. Walking disability in old age is a common condition requiring physical therapy. Intermittent pneumatic compression can be used as a physical therapy modality for this patient group.展开更多
Based on the zero-failure data of 30 Chinese 1. 5 MW wind turbine gearboxes( WTGs),the optimal confidence limit method was developed to predict the reliability and reliability lifetime of WTG. Firstly,Bayesian method ...Based on the zero-failure data of 30 Chinese 1. 5 MW wind turbine gearboxes( WTGs),the optimal confidence limit method was developed to predict the reliability and reliability lifetime of WTG. Firstly,Bayesian method and classical probability estimation method were introduced to estimate the value interval of shape parameter considering the engineering practice. Secondly,taking this value interval into the optimal confidence limit method,the reliability and reliability lifetime of WTG could be obtained under different confidence levels. Finally,the results of optimal confidence limit method and Bayesian method were compared. And the comparison results show that the rationality of this estimated range.Meantime, the rule of confidence level selection in the optimal confidence limit method is provided, and the reliability and reliability lifetime prediction of WTG can be acquired.展开更多
Seismic hazard levels lower than those for design of new buildings have been permitted for seismic evaluation and retrofi t of existing buildings due to the relatively short remaining lifespans. The seismic hazard red...Seismic hazard levels lower than those for design of new buildings have been permitted for seismic evaluation and retrofi t of existing buildings due to the relatively short remaining lifespans. The seismic hazard reduction enables costeff ective seismic evaluation and retrofi t of existing buildings with limited structural capacity. The current study proposes seismic hazard reduction factors for Korea, one of low to moderate seismicity regions. The seismic hazard reduction factors are based on equal probabilities of non-exceedance within diff erent remaining building lifespans. A validation procedure is proposed to investigate equality of seismic risk in terms of ductility-based limit states using seismic fragility assessment of nonlinear SDOF systems, of which retrofi t demands are determined by the displacement coeffi cient method of ASCE 41-13 for diff erent target remaining building lifespans and corresponding reduced design earthquakes. Validation result shows that the use of seismic hazard reduction factors can be permitted in conjunction with appropriate lower bounds of the remaining building lifespans.展开更多
Bentonite has been considered as the buffer material for embedding canisters with high-level radioactive waste(HLW)in the deep geology repositories. GMZ bentonite deposit which is located in Xinghe County,Inner Mongol...Bentonite has been considered as the buffer material for embedding canisters with high-level radioactive waste(HLW)in the deep geology repositories. GMZ bentonite deposit which is located in Xinghe County,Inner Mongolia has been proposed as buffer/backfill material for HLW repository in China. Liquid limit of natural Na-bentonite GMZ01 and commercial Na-bentonite MX80 which were previously put in the oven at 80℃and 95℃,and exposed to water for different times were measured.The liquid limit of GMZ01 increased slightly at the beginning, and then decreased as the heating time increased.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11574082)the Fundamental Research Funds for the Central Universities,China(Grant No.2018MS050)
文摘Propagation of strong femtosecond hyper-Gaussian pulses in a cascade three-level molecular system is studied by solving numerically the Maxwell–Bloch equations by the iterative predictor-corrector finite-difference time-domain method.Optical power limiting behavior induced by strong nonlinear two-photon absorption is observed for different orders of the femtosecond hyper-Gaussian pulses. Pulses of a higher order temporal profile are found to have a wider power range of optical limiting but a larger output saturation intensity. Both the output saturation value and the damage threshold of optical power limiting decrease with pulse duration increasing. The decrease of the pulse area along the pulse propagation is much slower than that obtained from the two-photon area theorem due to invalidity of the slowly varying amplitude approximation and the monochromatic field hypothesis.
文摘Background and Purpose: Walking difficulties are defined as any reduction in speed, balance, or change of gait, causing limited ambulation. These difficulties are a common problem in older adults and may greatly affect their quality of life (QOL) and restrict their personal independence and participation. This study aimed to determine the effect of intermittent pneumatic compression (IPC) on lower leg pain, walking capacity, functional mobility, ankle range of motion (AROM), and QOL of community-dwelling older people with walking difficulties. Methods: In this randomized controlled trial, 34 eligible participants with self-reported lower limb pain and limited ambulation were randomized either to the intermittent pneumatic compression intervention group (IPCIG) or static compression control group (SCCG). The IPCIG and SCCG were trained to receive IPC and SC respectively for both lower legs and instructed to continue the application independently at home for 15 minutes per session, 2 sessions a day, 7 days per week for 4 weeks independently at the home. Outcome measures of lower leg pain, AROM, walking capacity, and functional mobility were assessed at baseline and at the first, second, third, and fourth weeks after randomization. Quality of life was assessed at baseline and immediately after the intervention. Results and Discussion: IPCIG showed a more significant improvement compared to the SCCG at the post-interventional stage for QOL and all the subscales. The findings show that “80% improved QOL” is 53% higher with the application of IPC than with SC for 4 weeks. The IPCIG showed a more significant improvement in the 6-minute walk test (6 MWT) at the third and fourth weeks compared to the SCCG. A pairwise comparison of mean values of 6 MWT over 4 weeks within the IPCIG showed a significant difference between all the weeks. Pairwise comparisons between groups at each time point showed that the IPCIG showed a more significant improvement in the timed up and go (TUG) test at the third and fourth weeks compared to the SCCG. Pairwise comparison of mean values of TUG test within the IPCIG showed a significant difference over 4 weeks, except between the second and third weeks, fourth week, and third and fourth weeks. The IPCIG showed a more significant improvement in lower leg pain between all weeks except the first week compared to the SCCG. Pairwise comparison of mean values of lower leg pain over 4 weeks within the IPCIG showed a significant difference among all weekly outcomes except between 1 and 2 weeks. The IPCIG showed a more significant improvement in left and right ankle dorsiflexion ROM at the third and fourth weeks compared to the SCCG. Conclusions: The IPC was effective in reducing lower leg pain and increasing the AROM and improving the walking capacity, functional mobility level, and QOL of community-dwelling older people with walking disabilities. Walking disability in old age is a common condition requiring physical therapy. Intermittent pneumatic compression can be used as a physical therapy modality for this patient group.
基金National Natural Science Foundation of China(No.51265025)
文摘Based on the zero-failure data of 30 Chinese 1. 5 MW wind turbine gearboxes( WTGs),the optimal confidence limit method was developed to predict the reliability and reliability lifetime of WTG. Firstly,Bayesian method and classical probability estimation method were introduced to estimate the value interval of shape parameter considering the engineering practice. Secondly,taking this value interval into the optimal confidence limit method,the reliability and reliability lifetime of WTG could be obtained under different confidence levels. Finally,the results of optimal confidence limit method and Bayesian method were compared. And the comparison results show that the rationality of this estimated range.Meantime, the rule of confidence level selection in the optimal confidence limit method is provided, and the reliability and reliability lifetime prediction of WTG can be acquired.
基金supported by the Incheon National University Research Grant in 2015
文摘Seismic hazard levels lower than those for design of new buildings have been permitted for seismic evaluation and retrofi t of existing buildings due to the relatively short remaining lifespans. The seismic hazard reduction enables costeff ective seismic evaluation and retrofi t of existing buildings with limited structural capacity. The current study proposes seismic hazard reduction factors for Korea, one of low to moderate seismicity regions. The seismic hazard reduction factors are based on equal probabilities of non-exceedance within diff erent remaining building lifespans. A validation procedure is proposed to investigate equality of seismic risk in terms of ductility-based limit states using seismic fragility assessment of nonlinear SDOF systems, of which retrofi t demands are determined by the displacement coeffi cient method of ASCE 41-13 for diff erent target remaining building lifespans and corresponding reduced design earthquakes. Validation result shows that the use of seismic hazard reduction factors can be permitted in conjunction with appropriate lower bounds of the remaining building lifespans.
文摘Bentonite has been considered as the buffer material for embedding canisters with high-level radioactive waste(HLW)in the deep geology repositories. GMZ bentonite deposit which is located in Xinghe County,Inner Mongolia has been proposed as buffer/backfill material for HLW repository in China. Liquid limit of natural Na-bentonite GMZ01 and commercial Na-bentonite MX80 which were previously put in the oven at 80℃and 95℃,and exposed to water for different times were measured.The liquid limit of GMZ01 increased slightly at the beginning, and then decreased as the heating time increased.
