Optimized anti-vibratory system for stretched canvas artwork hanging in a museum     

《Journal of Cultural Heritage》2014,15(4):382-390

To prevent the deterioration of artwork on stretched canvas in a museum, it is often necessary to neutralize the transmission of vibrations from sources such as the wall or the floor. An anti-vibratory system easily optimizes vibrations that are transmitted from the floor because the artwork's motion occurs in vertical translation. Hanging artwork, which receives vibrations from the wall, presents a more complex case because the motion consists of a translation and a rotation. This paper presents a model to determine a cutting frequency above which vibrations transmitted to the artwork are lowered. A procedure to obtain the parameters of this model is also presented. Experiments in a laboratory and in the Louvre Museum validate the predicted cutting frequency given by the model. A downloadable spreadsheet is available to apply this method to specific artwork.  相似文献   

多冲击对与分布影响因素的系统动态效应（英文）     

V.L.Krupenin 《出版与印刷》2015,(1):31-41

<正>Introduction In this paper in general the dynamic effects are considered and described,caused by different standing waves in discrete and distributed systems with impacts and other strongly positional non-linear factors,introduction of which in the models of mechanical objects is dictated by the necessity to con-  相似文献   

移动荷载作用下桥梁的动态响应研究     

张彬  柳东委  刘波 《黑龙江科技信息》2009,(30):289-289,323

阐述移动载荷振动的分析理论,利用ANSYS对一单跨作模拟分析,从这一简单类型中找出动载荷对桥梁的动态响应做出分析。找出桥梁在动载荷作用下桥梁的变形规律及桥梁在不同激振频率下的桥梁变形规律,为桥梁设计提供可靠依据。  相似文献   

Wind-induced response analysis of a wind turbine tower including the blade-tower coupling effect     

Xiao-bo Chen  Jing Li  Jian-yun Chen 《浙江大学学报(A卷英文版)》2009,10(11):1573-1580

To analyze wind-induced response characteristics of a wind turbine tower more accurately, the blade-tower coupling effect was investigated. The mean wind velocity of the rotating blades and tower was simulated according to wind shear effects, and the fluctuating wind velocity time series of the wind turbine were simulated by a harmony superposition method. A dynamic finite element method （FEM） was used to calculate the wind-induced response of the blades and tower. Wind-induced responses of the tower were calculated in two cases （one included the blade-tower coupling effect, and the other only added the mass of blades and the hub at the top of the tower）, and then the maximal displacements at the top of the tower of the tow cases were compared with each other. As a result of the influence of the blade-tower coupling effect and the total base shear of the blades, the maximal displacement of the first case increased nearly by 300% compared to the second case. To obtain more precise analysis, the blade-tower coupling effect and the total base shear of the blades should be considered simultaneously in the design of wind turbine towers.  相似文献   

Comparison of vibration rolling,nonvibration rolling,and static stretching as a warm-up exercise on flexibility,joint proprioception,muscle strength,and balance in young adults     

Chia-Lun Lee  I-Hua Chu  Bo-Jhang Lyu  Wen-Dien Chang 《Journal of sports sciences》2018,36(22):2575-2582

Warm-up is an essential component for optimizing performance before an exercise session. This study investigated that the immediate effects of vibration rolling (VR), nonvibration rolling (NVR), and static stretching as a part of a warm-up regimen on the flexibility, knee joint proprioception, muscle strength, and dynamic balance of the lower extremity in young adults. Compared with the preintervention, VR induced the range of motion of knee flexion and extension significantly increased by 2.5% and 6%, respectively, and isokinetic peak torque and dynamic balance for muscle strength and dynamic balance increased by 33%–35% and 1.5%, respectively. In the three conditions, most outcomes between VR and NVR were comparable; however, the participants had a significantly higher knee joint reposition error after NVR than after VR, indicating that NVR would have a hampering knee joint proprioception effect. In particular, compared with static stretching, VR significantly increased the quadriceps muscle strength by 2-fold and dynamic balance by 1.8-fold. These findings suggest that athletic professionals may take VR into account for designing more efficient and effective preperformance routine to improve exercise performances. VR has high potential to translate into an on-field practical application.  相似文献   

工具的横向振动对超声加工精度的影响     

金德新 《鞍山师范学院学报》2002,4(3):93-95

根据系统的固有频率振型理论、系统的响应,分析了影响加工精度的因素,提出在设计和加工时应注意的问题和应采取的措施.  相似文献   

二杆柔性臂动力学建模与控制     

陶泽  郝长中  张华 《辽宁科技学院学报》2002,4(2):1-3,9

用Lagrange方程对二杆柔性臂进行了动力学建模，并且研究了压电智能结构的柔性机械臂的控制，以二杆柔性臂为例讨论了压电传感器/作动器的位置、数量、尺寸以及控制增益对智能柔性臂振动控制效果的影响，可以实时、有效地控制系统的弹性振动。  相似文献   

用CASSY研究RLC电路的振荡特性     

崔百宁 《青海师专学报》1997,17(2):50-53

用计算机辅助测量和分析系统ＣＡＳＳＹ研究了ＲＬＣ电路。，该系统能迅速，直观地显示实验结果。  相似文献   

高层建筑风振反应被动控制     

方小兵 《五邑大学学报(社会科学版)》1992,(1)

本文采用矩阵传递法分析了调频质量阻尼器(TMD)被动控制高层建筑风振反应,导出了结构顶层位移、加速度和基底剪力频域内统计特征公式。最后通过实例的结果说明,经过控制后能显著地降低风振反应。  相似文献   

A disc-type magneto-rheologic fluid damper     

祝长生 《浙江大学学报(A卷英文版)》2003,4(5)

A disc-type magneto-rheological fluid damper operating in shear mode is proposed in this paper, which is based on the special characteristics of the magneto-rheological (MR) fluid with rapid, reversible and dramatic change in its rheological properties by the application of an external magnetic field. The magnetic field of the disc-type MR fluid damper is analysed by the finite element method; the controllability of the disc-type MR fluid damper on the dynamic behaviour of a rotor system; and the effectiveness of the disc-type MR fluid damper in controlling the vibration of a rotor system, are studied in a flexible rotor system with an over-hung disc. It is shown that the magnetic flux density of the disc-type MR fluid damper in the working areas can significantly change with the applied current in the coil; and that the dynamic behavior of the disc-type MR fluid damper can be varied by the application of an external magnetic field produced by a low voltage electromagnetic coil. The disc-type MR fluid damper can significantly change the dynamic characteristics of a rotor system, provided that the location of the disk-type MR fluid damper is carefully chosen. The disc-type MR fluid damper is a new actuator with good dynamic characteristics for rotating machinery.  相似文献