航天支架结构的被动振动控制

重点研究了航天支架结构的被动振动控制问题。在约束阻尼层有限元模型理论分析的基础上，对未附加约束阻尼层的支架计算模态和试验模态进行了相关性分析，制定出被动振动控制策略；通过分析附加约束阻层后支架计算模态和试验模态相关性，建立了有效的支架有限元模型，进一步用于各种情况的动态响应计算和分析。计算了实验结果表明，该控制策略取得了很好的减振效果，为同类结构振动控制问题提供了一个良好的模型参考。     

A Mechanistic Approach to Tributyltin (TBT) Sorption by Marine Microflagellated Alga Pavlova lutheri

The sorption of tributyltin (TBT) by phytoplankton cells was studied by exposing the marine microflagellated alga Pavlova lutheri grown in batch culture to TBT chloride concentrations ranging from 0.37 to 74 nM (0.1 to 21 μg l⁻¹) for a 24-hour period. The phytotoxicity of TBT was indicated by a decrease in cell density at all TBT concentrations used. TBT was tightly bound to the surface cell and was only washed out by a strong acidic solution (pH⩽3) while inner cell-absorbed TBT was only recovered by means of an organic solvent. The sorption of TBT by P. lutheri occurred via two mechanisms: a passive ionic surface adsorption followed by a facilitated intracellular absorption. The coupling/uncoupling of these two mechanisms was dependent upon the contamination level used. The cell surface adsorption of TBT was best described by the Freundlich adsorption model whereas the obstruction of the facilitated absorption mechanism was apparently related to the toxic activity of TBT towards cell components. © 1997 John Wiley & Sons, Ltd.     

金属│固体电解质│含水凝胶│石墨体系的研究

应用点缺陷模型和双层模型分析了金属│固体电解质│含水凝胶│石墨体系贮藏和放电时金属表面氧化膜的变化.在固体电解质含有微量水分的情况下,微量水分有助于金属表面形成松层,但由于水分子与紧密钝化膜的持续作用,金属表面松层厚度会不断增长,孔率降低,使得电池的电压和放电电流下降.松层的孔率强烈影响膜溶解行为,与紧密钝化膜的电学特性一样,松层也是一种半导体.     

浅海单矢量传感器宽带声源三维定位仿真

针对水平不变的浅海波导中单矢量传感器对低频宽带声源的三维被动定位问题,首先利用平均声强器估计声源方位;其次,通过分离简正模的声压和水平振速分量联合处理获得运动声源相对速度,进一步基于垂直声能流中简正模相干项特征频率不变性以及长时间窗口中多快拍信号的统一处理,建立WARPING变换频谱作为代价函数的搜索处理器,估计该段信号的初始距离,进而获得各时刻声源距离,所提出的方法避免了对拷贝声场和引导声源的依赖;最后,利用多阶简正模相干项与非相干项能量模基处理方法,当声场中存在三阶以上简正模时,可对声源深度进行匹配估计。仿真分析表明,单个矢量传感器能够给出声源的方位、距离及深度估计结果。     

Long-Term Potentiodynamic Testing and Tribometric Properties of Amorphous Alloy Coatings under Saline Environment

Protective coatings for harsh environments are always welcome, but they must overcome profound challenges, including corrosion and wear resistance. The purpose of this study is to look into the long-term potentiodynamic polarization measurements and dry tribometric behavior of plasma-sprayed amorphous coatings on AISI 1035 mild steel. To investigate the impact of unique active polarization potentials on the electrochemical studies of the iron-based amorphous layer, which compares favorably to AISI 1035 mild steel, the active potential polarization curve and friction coefficient tests were performed. Scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) analyses were used to investigate the coating’s corrosion behavior. Their mechanical (Tribometric tests at higher sliding speeds) and chemical properties (electrochemical potentiodynamic polarization investigations) have also been thoroughly investigated. There is enough validation that these protective coatings can be used in hostile environments. The effects of long-term corrosion for 24 and 48 h were thoroughly examined. Tribometric examinations revealed that amorphous layers are highly resistant under dry conditions, as they offered a very low and stable friction coefficient less than 4 μ with micro Vickers hardness 1140 ± 22.14 HV, which is more than twice as compared to mild steel AISI 1035. The corrosion resistance of coatings in 3.5 wt % NaCl solution displays active transition characteristics of activation, passivation, over passivation, and pitting, as shown by the potentiodynamic polarization curves.     

有源微型环腔谐振器的数值仿真

结合载流子速率方程以及时域有限差分(FDTD)法,通过将增益因子等效引入电导率,成功实现了有源微型环腔谐振器的数值仿真,并模拟了有源微环的传输特性.仿真结果表明,有源微环存在谐振波长漂移的现象.由于增益的作用,有源微环的谐振光场建立时间比无源微环要短,直通端口消光更快,表明有源微环比无源微环具有更高的开关速度.