期刊文献+
共找到3篇文章
< 1 >
每页显示 20 50 100
聚丙烯/聚乙烯共混物环状型坯挤出膨胀和垂伸的研究 被引量:2
1
作者 林登辉 黄汉雄 王建康 《塑料科技》 CAS 北大核心 2006年第5期52-55,共4页
利用双螺杆挤出机将聚丙烯分别与不同熔体流动速率的聚乙烯进行共混,通过环状型坯挤出,研究了共混物的型坯膨胀和垂伸情况。结果表明,聚丙烯与较高熔体流动速率的聚乙烯共混后,其型坯直径膨胀的变化范围较宽,垂伸较明显。
关键词 聚丙烯 聚乙烯 共混 型坯 膨胀 垂伸
下载PDF
圆环和锥形口模挤出吹塑的数值研究
2
作者 李静 彭炯 +2 位作者 刘沙粒 于涛 张丁 《工程塑料应用》 CAS CSCD 北大核心 2012年第12期46-49,共4页
用Polyflow软件的Carreau本构模型,数值模拟了用于管材挤出吹塑和型坯成型的圆环口模和锥形口模内熔体及其型坯的三维等温流场,考虑了挤出胀大和垂伸效应的综合影响,分析了两种口模的差异。数值计算结果表明,对于同一直径和口模间隙的... 用Polyflow软件的Carreau本构模型,数值模拟了用于管材挤出吹塑和型坯成型的圆环口模和锥形口模内熔体及其型坯的三维等温流场,考虑了挤出胀大和垂伸效应的综合影响,分析了两种口模的差异。数值计算结果表明,对于同一直径和口模间隙的环形口模和锥形口模,在相同入口流量下,环形口模内熔体的压力梯度大于锥形口模,环形口模成型型坯的厚度小于锥形口模,环形口模成型型坯的直径大于锥形口模;环形和锥形口模内熔体的压力梯度随着入口流量的增加而增加,在环形和锥形口模成型型坯的底端,型坯的厚度和外半径随着入口流量的增加而增加;锥形口模成型型坯厚度较环形口模对流量更敏感。 展开更多
关键词 挤出胀大 垂伸效应 环形口模 锥形口模 数值模拟
下载PDF
Effect of different stretching strategies on the kinetics of vertical jumping in female volleyball athletes 被引量:2
3
作者 Nicholas T. Kruse Marcus W. Barr +2 位作者 Roger M. Gilders Michael R. Kushnick Sharon R. Rana 《Journal of Sport and Health Science》 SCIE 2015年第4期364-370,共7页
Purpose: The present study aimed to examine the effect of static stretching (SS) and a sport-specific dynamic stretching (DS) session at two specific post-stretch time intervals in highly trained female athletes ... Purpose: The present study aimed to examine the effect of static stretching (SS) and a sport-specific dynamic stretching (DS) session at two specific post-stretch time intervals in highly trained female athletes (age 19.90 ± 1.60 years; height 1.80 ±0.06 m; mass 76.87 ± 9.95 kg) on kinetic parameters of peak force, time-to-takeoff, and rate of force development. Methods: The data were collected over 3 days (randomized within subject design with control session). Following each stretch session (SS vs. DS vs. control) of equal duration (7 min total: 30 s per targeted muscle group) participants performed countermovement jumping on a force platform at 1 and 15 rain after stretching. Results: The DS session significantly improved upon kinetic variables of rate of force development, peak force, and time-to-takeoffrelative to SS at 1 min after stretching. No significant effect was found at 15 min. Conclusion: Together these findings suggest that when training and competing to jump quickly and maximally the female athlete should incorporate DS instead of SS as part of their pre-competition warm-up, but conduct performance within 15 min of their warm-up to elicit maximal gains 展开更多
关键词 Dynamic stretching Female athletes Rate of force development Static stretching Time-to-takeoff
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部