Tuned mass dampers （TMDs） have been widely used in recent years to mitigate structural vibration. However, the damping mechanisms employed in the TMDs are mostly based on viscous dampers, which have several well-kno...Tuned mass dampers （TMDs） have been widely used in recent years to mitigate structural vibration. However, the damping mechanisms employed in the TMDs are mostly based on viscous dampers, which have several well-known disadvantages, such as oil leakage and difficult adjustment of damping ratio for an operating TMD. Alternatively, eddy current damping （ECD） that does not require any contact with the main structure is a potential solution. This paper discusses the design, analysis, manufacture and testing of a large-scale horizontal TMD based on ECD. First, the theoretical model of ECD is formulated, then one large-scale horizontal TMD using ECD is constructed, and finally performance tests of the TMD are conducted. The test results show that the proposed TMD has a very low intrinsic damping ratio, while the damping ratio due to ECD is the dominant damping source, which can be as large as 15% in a proper configuration. In addition, the damping ratios estimated with the theoretical model are roughly consistent with those identified from the test results, and the source of this error is investigated. Moreover, it is demonstrated that the damping ratio in the proposed TMD can be easily adjusted by varying the air gap between permanent magnets and conductive plates. In view of practical applications, possible improvements and feasibility considerations for the proposed TMD are then discussed. It is confirmed that the proposed TMD with ECD is reliable and feasible for use in structural vibration control.展开更多
针对现有结构模型减振实验用调谐质量阻尼器(Tuned Mass Damper,TMD)难以实现TMD刚度与阻尼参数完全分离、阻尼参数试验过程中无法保持恒定且难以调整问题,研制微型永磁式电涡流阻尼TMD。其性能试验与分析结果表明,微型TMD采用电涡流阻...针对现有结构模型减振实验用调谐质量阻尼器(Tuned Mass Damper,TMD)难以实现TMD刚度与阻尼参数完全分离、阻尼参数试验过程中无法保持恒定且难以调整问题,研制微型永磁式电涡流阻尼TMD。其性能试验与分析结果表明,微型TMD采用电涡流阻尼装置既能确保刚度与阻尼参数的有效分离,亦能实现阻尼参数稳定、简单易调。通过某大跨度人行桥模型一阶横向振动模态自由振动减振实验识别获得结构模态阻尼比及强迫振动减振实验识别获得结构模态阻尼比、结构动力响应放大倍数、结构与TMD运动相位差等,证实微型永磁式电涡流阻尼TMD用于结构模型减振实验的可行性与有效性。展开更多
目的观察经颅直流电刺激(tDCS)对恢复期卒中后失语患者视听觉通道命名能力的影响。方法 2018年3月至11月,32例恢复期卒中后失语患者随机分为对照组和实验组,各16例。实验组在左侧额下回(L-IFG)实施阳极tDCS,对照组实施假tDCS,刺激的同...目的观察经颅直流电刺激(tDCS)对恢复期卒中后失语患者视听觉通道命名能力的影响。方法 2018年3月至11月,32例恢复期卒中后失语患者随机分为对照组和实验组,各16例。实验组在左侧额下回(L-IFG)实施阳极tDCS,对照组实施假tDCS,刺激的同时行语言训练。治疗前和治疗2周后,采用西方失语症成套测试(WAB)、图片命名测试和环境声音命名测试进行评定。结果对照组15例、实验组16例完成实验。治疗后,两组WAB失语商均显著提高(t> 5.081, P <0.001),治疗前后差值两组间无显著性差异(t=1.550, P> 0.05);两组图片命名评分均明显提高(Z> 2.650, P <0.01),治疗前后差值实验组高于对照组(Z=-2.258, P <0.05);实验组WAB实物命名评分明显提高(Z=-3.239, P <0.01),治疗前后差值实验组明显高于对照组(Z=-3.008, P <0.01);实验组环境声音命名评分显著提高(t=-4.745, P <0.001),治疗前后差值实验组高于对照组(t=2.224, P <0.05);实验组WAB自发命名、WAB完成句子、WAB反应命名评分均提高(Z> 2.191, P <0.05),对照组WAB自发命名评分提高(Z=-2.376, P <0.05),治疗前后差值两组间均无显著性差异(Z <1.568, P> 0.05)。结论 tDCS阳极刺激L-IFG对视觉和听觉通道的命名能力均有改善作用,可能通过影响语义或语音加工提高命名能力。展开更多
基金State Key Program of Natural Science Foundation of China Under Grant No.50738002
文摘Tuned mass dampers （TMDs） have been widely used in recent years to mitigate structural vibration. However, the damping mechanisms employed in the TMDs are mostly based on viscous dampers, which have several well-known disadvantages, such as oil leakage and difficult adjustment of damping ratio for an operating TMD. Alternatively, eddy current damping （ECD） that does not require any contact with the main structure is a potential solution. This paper discusses the design, analysis, manufacture and testing of a large-scale horizontal TMD based on ECD. First, the theoretical model of ECD is formulated, then one large-scale horizontal TMD using ECD is constructed, and finally performance tests of the TMD are conducted. The test results show that the proposed TMD has a very low intrinsic damping ratio, while the damping ratio due to ECD is the dominant damping source, which can be as large as 15% in a proper configuration. In addition, the damping ratios estimated with the theoretical model are roughly consistent with those identified from the test results, and the source of this error is investigated. Moreover, it is demonstrated that the damping ratio in the proposed TMD can be easily adjusted by varying the air gap between permanent magnets and conductive plates. In view of practical applications, possible improvements and feasibility considerations for the proposed TMD are then discussed. It is confirmed that the proposed TMD with ECD is reliable and feasible for use in structural vibration control.
文摘针对现有结构模型减振实验用调谐质量阻尼器(Tuned Mass Damper,TMD)难以实现TMD刚度与阻尼参数完全分离、阻尼参数试验过程中无法保持恒定且难以调整问题,研制微型永磁式电涡流阻尼TMD。其性能试验与分析结果表明,微型TMD采用电涡流阻尼装置既能确保刚度与阻尼参数的有效分离,亦能实现阻尼参数稳定、简单易调。通过某大跨度人行桥模型一阶横向振动模态自由振动减振实验识别获得结构模态阻尼比及强迫振动减振实验识别获得结构模态阻尼比、结构动力响应放大倍数、结构与TMD运动相位差等,证实微型永磁式电涡流阻尼TMD用于结构模型减振实验的可行性与有效性。
文摘目的观察经颅直流电刺激(tDCS)对恢复期卒中后失语患者视听觉通道命名能力的影响。方法 2018年3月至11月,32例恢复期卒中后失语患者随机分为对照组和实验组,各16例。实验组在左侧额下回(L-IFG)实施阳极tDCS,对照组实施假tDCS,刺激的同时行语言训练。治疗前和治疗2周后,采用西方失语症成套测试(WAB)、图片命名测试和环境声音命名测试进行评定。结果对照组15例、实验组16例完成实验。治疗后,两组WAB失语商均显著提高(t> 5.081, P <0.001),治疗前后差值两组间无显著性差异(t=1.550, P> 0.05);两组图片命名评分均明显提高(Z> 2.650, P <0.01),治疗前后差值实验组高于对照组(Z=-2.258, P <0.05);实验组WAB实物命名评分明显提高(Z=-3.239, P <0.01),治疗前后差值实验组明显高于对照组(Z=-3.008, P <0.01);实验组环境声音命名评分显著提高(t=-4.745, P <0.001),治疗前后差值实验组高于对照组(t=2.224, P <0.05);实验组WAB自发命名、WAB完成句子、WAB反应命名评分均提高(Z> 2.191, P <0.05),对照组WAB自发命名评分提高(Z=-2.376, P <0.05),治疗前后差值两组间均无显著性差异(Z <1.568, P> 0.05)。结论 tDCS阳极刺激L-IFG对视觉和听觉通道的命名能力均有改善作用,可能通过影响语义或语音加工提高命名能力。
