A new structural system called a stepped wall-frame structure is proposed in this study to solve the bottom yielding problem of RC frames, which widely occurred during previous earthquakes such as thc Wcnchuan and Yus...A new structural system called a stepped wall-frame structure is proposed in this study to solve the bottom yielding problem of RC frames, which widely occurred during previous earthquakes such as thc Wcnchuan and Yushu earthquakes in China. A 1/5 scale ordinary RC frame model and a stepped wall-frame model were subjected to shake table motions together to study the seismic behavior of the new structural system. This paper presents the dynamic characteristics, the seismic responses and the failure and collapse mechanism of the two models under low, moderate and high intensity shaking. The test results and further analysis demonstrate that the seismic performance of stepped wall-frame structures is superior to ordinary RC frames in terms of the well-controlled deformation pattern and more uniformly distributed damage. The stepped wall can effectively suppress the bottom yielding mechanism, and is simple, economical and practical tbr engineering practice.展开更多
The Electroluminescence thin films of zinc sulfide do ped with erbium, fabricated by thermal evaporation with two boats, are analyzed by the technology of X-ray diffraction (XRD) and X-ray photoelectron spectrosc opy ...The Electroluminescence thin films of zinc sulfide do ped with erbium, fabricated by thermal evaporation with two boats, are analyzed by the technology of X-ray diffraction (XRD) and X-ray photoelectron spectrosc opy (XPS). The relationship between electroluminescence brightness and microst ructure of the thin films is obtained. The analysis results of XRD indicate th at the fabricated zinc sulfide thin films belong to the blende structure and hav e a trend of preferential orientation. The XPS measurements reveal the surface m icrostructure states formed mainly by oxygen absorption and carbon absorption th at effect on the EL excitation and relaxation luminescence process. The maximum photoelectron peak corresponding to the doped erbium is detected at a depth of 1 35nm to 350nm that formed the activation layer in the films. Analysis shows that the high brightness of the film devices is attributed to the crystalline planes of growth orientated in the (311), (400). In explanation of this phenomenon, th e status of the substitute energy for Er 3+ replacing Zn 2+ in the hos t lattice of zinc sulfide is discussed. All results of describing above are referable in researching of the electroluminescence excitation machnism of the t hin film devices and in favor of fabricating the thin film devices with high qua lity.展开更多
提出一种采用石墨自润滑球铰连接的立方体构型Stewart隔振平台,6个支腿通过可转动的球铰与基础及载荷平台相连,每个支腿由音圈作动器与力传感器构成。在假设各支腿、基础及载荷平台均为弹性体的基础上,采用子结构频响函数综合法对Stewar...提出一种采用石墨自润滑球铰连接的立方体构型Stewart隔振平台,6个支腿通过可转动的球铰与基础及载荷平台相连,每个支腿由音圈作动器与力传感器构成。在假设各支腿、基础及载荷平台均为弹性体的基础上,采用子结构频响函数综合法对Stewart隔振平台进行动力学建模,并通过FEM方法进行验证,给出内嵌反馈控制的隔振平台模型,对反馈控制效果进行仿真验证;在仿真分析的基础上,对隔振平台的被动隔振性能和内嵌反馈控制的主动隔振性能进行实验。结果表明,被动隔振在30~200 Hz频段内具有约-36 d B/dec的衰减率,主动隔振在3~100 Hz频段内可获得最大20 d B的幅值衰减,<200 Hz,支腿力RMS值控制后下降75%~80%。展开更多
基金Special Fund for Earthquake Research under Grant No.201208013National key Technology R&D Program under Grant No.2012BAK15B05Basic Research Fund of Institute of Engineering Mechanics,CEA under Grant No.2010A04
文摘A new structural system called a stepped wall-frame structure is proposed in this study to solve the bottom yielding problem of RC frames, which widely occurred during previous earthquakes such as thc Wcnchuan and Yushu earthquakes in China. A 1/5 scale ordinary RC frame model and a stepped wall-frame model were subjected to shake table motions together to study the seismic behavior of the new structural system. This paper presents the dynamic characteristics, the seismic responses and the failure and collapse mechanism of the two models under low, moderate and high intensity shaking. The test results and further analysis demonstrate that the seismic performance of stepped wall-frame structures is superior to ordinary RC frames in terms of the well-controlled deformation pattern and more uniformly distributed damage. The stepped wall can effectively suppress the bottom yielding mechanism, and is simple, economical and practical tbr engineering practice.
文摘The Electroluminescence thin films of zinc sulfide do ped with erbium, fabricated by thermal evaporation with two boats, are analyzed by the technology of X-ray diffraction (XRD) and X-ray photoelectron spectrosc opy (XPS). The relationship between electroluminescence brightness and microst ructure of the thin films is obtained. The analysis results of XRD indicate th at the fabricated zinc sulfide thin films belong to the blende structure and hav e a trend of preferential orientation. The XPS measurements reveal the surface m icrostructure states formed mainly by oxygen absorption and carbon absorption th at effect on the EL excitation and relaxation luminescence process. The maximum photoelectron peak corresponding to the doped erbium is detected at a depth of 1 35nm to 350nm that formed the activation layer in the films. Analysis shows that the high brightness of the film devices is attributed to the crystalline planes of growth orientated in the (311), (400). In explanation of this phenomenon, th e status of the substitute energy for Er 3+ replacing Zn 2+ in the hos t lattice of zinc sulfide is discussed. All results of describing above are referable in researching of the electroluminescence excitation machnism of the t hin film devices and in favor of fabricating the thin film devices with high qua lity.
文摘提出一种采用石墨自润滑球铰连接的立方体构型Stewart隔振平台,6个支腿通过可转动的球铰与基础及载荷平台相连,每个支腿由音圈作动器与力传感器构成。在假设各支腿、基础及载荷平台均为弹性体的基础上,采用子结构频响函数综合法对Stewart隔振平台进行动力学建模,并通过FEM方法进行验证,给出内嵌反馈控制的隔振平台模型,对反馈控制效果进行仿真验证;在仿真分析的基础上,对隔振平台的被动隔振性能和内嵌反馈控制的主动隔振性能进行实验。结果表明,被动隔振在30~200 Hz频段内具有约-36 d B/dec的衰减率,主动隔振在3~100 Hz频段内可获得最大20 d B的幅值衰减,<200 Hz,支腿力RMS值控制后下降75%~80%。
