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土工袋挡土墙动力特性影响因素试验 被引量:2
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作者 李玲君 刘斯宏 +1 位作者 徐小东 张雨灼 《水利水电科技进展》 CSCD 北大核心 2015年第6期41-46,共6页
为了解土工袋挡土墙这一新型柔性挡土墙的动力特性,通过小型振动台模型试验,研究了地震三要素(输入加速度、振动频率、振动持续时间)以及土工袋大小对以天然河砂为填料的土工袋挡土墙动力特性的影响,分析了水平位移、动土压力以及加速... 为了解土工袋挡土墙这一新型柔性挡土墙的动力特性,通过小型振动台模型试验,研究了地震三要素(输入加速度、振动频率、振动持续时间)以及土工袋大小对以天然河砂为填料的土工袋挡土墙动力特性的影响,分析了水平位移、动土压力以及加速度的变化规律。试验结果表明,输入加速度越大,振动频率越低,土工袋挡土墙位移与动土压力系数越大,加速度响应则随着输入加速度和振动频率的增大而增大,而振动持续时间对土工袋挡土墙的动力特性影响不大;与普通大小的土工袋相比,由大土工袋构筑的挡土墙抗震性能略差,但施工方便快捷,效率较高,可应用于抗震要求较低的地区或者工期较紧的工程。 展开更多
关键词 土工袋挡土墙 动力特性 地震加速度 振动频率 动力持时 振动台模型试验
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INFLUENCE OF DIFFERENT NEEDLE-RETAINING DURATION ON CEREBRAL HEMODYNAMICS OF CEREBRAL PARALYSIS CHILDREN 被引量:1
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作者 袁青 王琴玉 +3 位作者 冯健强 张壮涛 陈雪云 靳瑞 《World Journal of Acupuncture-Moxibustion》 2004年第2期7-10,共4页
Objective: To investigate the effects of different needle-retaining duration on cerebral hemodynamics in cerebral paralysis (CP) children. Methods: A total of 20 cases of CP children were subjected into this study. Ch... Objective: To investigate the effects of different needle-retaining duration on cerebral hemodynamics in cerebral paralysis (CP) children. Methods: A total of 20 cases of CP children were subjected into this study. Changes of systolic peak value (Vs), blood flow velocity at the end-diastolic phase (Ved), mean velocity (Vm), pulsation index (PI) and resistance index (RI) of the cerebral hemodynamics before and after performing JIN’s Three-Needling Therapy with the needles retained for 30 min (group A) and 5 min (group B) were observed by using transcranial Doppler ultrasonography (TCD). Results: After acupuncture, the blood flow in the middle cerebral artery (MCA), anterior cerebral artery (ACA) and posterior cerebral artery (PCA) was accelerated, and the resistance of blood vessels decreased. The effect of needle-retaining-30 min was better than that of needle-retaining-5 min. Conclusion: In treating cerebral paralysis by using JIN’s Three-Needling Therapy, sufficient stimulation provided by needle remaining is an important factor for achieving satisfactory therapeutic effects. 展开更多
关键词 JIN's Three-Needling Therapy Cerebral paralysis Time-effect relation Transcranial Doppler ultrasonography (TCD)
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Characteristics of the double layer associated with terrestrial bow shock by THEMIS observation
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作者 LI ShiYou ZHANG ShiFeng +2 位作者 CAI Hong BAI XiBin XIE QiuHong 《Science China Earth Sciences》 SCIE EI CAS CSCD 2015年第4期562-572,共11页
This study presents observation and detailed analysis on the double layers (DLs) in the ramp and the foreshock contacting with the foot of the terrestrial bow shock by THEMIS on September 14, 2008 under enhanced dyn... This study presents observation and detailed analysis on the double layers (DLs) in the ramp and the foreshock contacting with the foot of the terrestrial bow shock by THEMIS on September 14, 2008 under enhanced dynamic pressure in the solar wind. The results reveal that: (1) The time duration of the double layers is nus 10-40 mV/m. (2) On assuming a propagation speed at the ion mainly 3-8 ms, and their max parallel electric field is miacoustic speed (vs), their spatial scale is estimated to be 0.3-1.15 km (about 75-200 2D). (3) The net potential drop of DLs is estimated to be 5-32 V. (4) The DLs in the ramp and the foreshock contacting to the foot of the bow shock is current-carrying as a result of development and evolution of nonlinear phase of instability in the self-consistent current-carrying plasma. The DLs may play an important role in strong turbulence in the foreshock contacting with the foot of the bow shock. 展开更多
关键词 bow shock double layer electron hole current-carrying plasma
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