There are actually no sufficient data for lifting technique assessment.A laboratory study was undertaken to determine the effect of 3 regular lifting techniques on erector muscle activation,cardiovascular strain and s...There are actually no sufficient data for lifting technique assessment.A laboratory study was undertaken to determine the effect of 3 regular lifting techniques on erector muscle activation,cardiovascular strain and subjective response.Thirty student volunteers participated in the study,and were required to lift a weight with different techniques.Stoop-,squat-,semi-squat-lifting resulted in 3,2 and 1 time of the highest percentage of the maximum voluntary electrical activation(MVE%) respectively.In the same order,the lowest median frequency(MF) existed 1,1 and 2 times.Muscle fatigue was 4 times in squat,36 in semi-squat and 43 in stoop lifting.Heart rate was the highest in squat and lowest in stoop respectively,with a middle level in semi-squat lifting.It may be recommended to adopt mainly the semi-squat technique for daily lifting works.For heavy lifting,it should use the squat technique.Stoop lifting may also be used alternatively but for light things.展开更多
The dynamics of the gravitational lifting system of the deep sea mining industry is demonstrated in this article.A simplified dynamic model is obtained when gravity,buoyancy and drag force are the major concerns.By qu...The dynamics of the gravitational lifting system of the deep sea mining industry is demonstrated in this article.A simplified dynamic model is obtained when gravity,buoyancy and drag force are the major concerns.By quantitative analysis,different variables like bucket size,distribution distance,and filling rate are considered to measure their influence on lifting speed and production rate,which ends up with that the most influential factor is the bucket size,and it has a positive correlation with both the two targets:lifting speed and production rate.Due to the breaking strength of the cable wire rope,a feasible design of such a lifting system should take the tension force into consideration.Hence,the feasibility is also examined and a conclusion is summarized that a combination of the bucket size and the distribution distance should be optimized according to the concrete working conditions.展开更多
基金supported in part by a grant from the Chinese Ministry of Science and Technology (No. 2006BAI06B08)
文摘There are actually no sufficient data for lifting technique assessment.A laboratory study was undertaken to determine the effect of 3 regular lifting techniques on erector muscle activation,cardiovascular strain and subjective response.Thirty student volunteers participated in the study,and were required to lift a weight with different techniques.Stoop-,squat-,semi-squat-lifting resulted in 3,2 and 1 time of the highest percentage of the maximum voluntary electrical activation(MVE%) respectively.In the same order,the lowest median frequency(MF) existed 1,1 and 2 times.Muscle fatigue was 4 times in squat,36 in semi-squat and 43 in stoop lifting.Heart rate was the highest in squat and lowest in stoop respectively,with a middle level in semi-squat lifting.It may be recommended to adopt mainly the semi-squat technique for daily lifting works.For heavy lifting,it should use the squat technique.Stoop lifting may also be used alternatively but for light things.
文摘The dynamics of the gravitational lifting system of the deep sea mining industry is demonstrated in this article.A simplified dynamic model is obtained when gravity,buoyancy and drag force are the major concerns.By quantitative analysis,different variables like bucket size,distribution distance,and filling rate are considered to measure their influence on lifting speed and production rate,which ends up with that the most influential factor is the bucket size,and it has a positive correlation with both the two targets:lifting speed and production rate.Due to the breaking strength of the cable wire rope,a feasible design of such a lifting system should take the tension force into consideration.Hence,the feasibility is also examined and a conclusion is summarized that a combination of the bucket size and the distribution distance should be optimized according to the concrete working conditions.
