Electrochromic Variation of the Infrared Emissivity in Tungsten Oxide Compounds

The so-called plastic technology first developed for the Li-based batteries leads to a new flexible infrared modulator. Orthorhombic monohydrated tungsten oxide (o-WO³ · H₂O) is used as the active insertion element in the LiCoO₂/o-WO³ · H₂O system. To prevent its degradation under air moisture, the device is protected with hermetic plastic and a window. Measurements of the reflectivity values indicate a very good contrast between the bleached and colored states for the first insertion (about 50% contrast in the 2.5–15 μm range), but the contrast between the inserted and de-inserted states is only about 30%. Optical properties follow quite well Drude mechanism.     

Flexible integration of optical switch with optical power splitting and attenuating functions for optical fiber-based networking applications

A flexible integration of optical switch with optical power splitting and attenuating functions has been proposed to optimally serve optical fiber-based networking applications. In this switch, an etched binary-slope sidewall reflector is electrostatically actuated in and out of the plane to manipulate optical signals between input and output optical fibers. The fabrication process is a simple combination of a bulk-silicon micromachining process and silicon-to-glass anodic bonding where fiber alignment grooves, reflectors and actuators are fabricated on the same silicon substrate. Ball-lensed fibers are assembled with the device to achieve high coupling efficiency. Performances of the fabricated devices are measured and discussed. The switching time is less than 9 ms at 31 V. The excess loss of the device is less than 3 dB and the controllable attenuation range is up to 38 dB at 139 V, respectively. Moreover, polarization-dependent loss is less than 0.7 dB in the whole attenuation and splitting range.     

On the nonlinear dynamics and control of flexible orbiting manipulators

The paper studies nonlinear dynamics and control of a class of space station based mobile flexible two-link manipulators, normally referred to as the Mobile Servicing System (MSS).The governing nonlinear, nonautonomous and coupled equations of motion are described first followed by the modal discretizations procedure. A parametric response study suggests situations with unacceptable levels of deflections and accelerations for certain proposed missions, as well as station libration and payload positioning errors.An inverse control technique is proposed to achieve high tracking accuracy of the MSS in presence of maneuver induced disturbances. The control strategy is so designed as to regulate the libration of the Space Station as well as to insure joints tracking of prescribed trajectories, while limiting the effect of the structural vibration during large slewing maneuvres of the MSS. Two different control schemes, both based on the feedback linearization technique, are developed and their relative merit assessed.This investigation was supported by the Centers of Excellence Program, Grant No. IRIS/C-8, 5-55380, and Natural Sciences and Engineering Research Council of Canada, Grant No. A-2181.     

同步辐射弧矢聚焦晶体压弯原理

本文通过优化晶体弯曲过程的旋转点,理论上分析了弧矢聚焦晶体弯曲原理、弯曲所造成的系统误差以及弯曲过程中晶体面形精度的变化;介绍了以柔性铰链为基本单元的精密工作台弯曲晶体的工作原理及其造成的系统误差.     

挠性多体系统动力学

本文以递推形式给出了挠性多体系统的动力学方程。此方程具有如下特点:(1)对整个系统而言,方程数目多,但递推的每一步只需要解低维的方程组,从而避免了高维矩阵的求逆,减少了计算量。(2)对不同类型的问题,方程形式具有很高的相似性,便于程序编制,各个需要求逆的矩阵都是对称正定的,这样减少了计算量和计算机内存单元。(3)这种方程形式处理非树形和带有约束条件的系统很方便。     

MOLECULAR FIELD THEORY FOR NEMATIC LIQUID CRYSTAL POLYMER COMPRISING FLEXIBLE SPACER

<正> Basea on the new model and concept of mtramolecular orientational order parameter, a molecular field theory was built up for main chain liquid crystalline polymer （MC-LCPs） with flexible spacers. The theory takes account of orientational correlation among all mesogens in a polymer chain and the relationship between the intramolecular orientation and spatial orientation of the mesogens. The free energy, temperature and entropy of the nematic-isotropic transition were determined with the theory and compared with experiments in current work. It was found that many unique transition properties of the MC-LCPs comprising flexible spacer are correctly predicted by the theory and the agreement of the theory with the experiments is impressive.     

含柔性间隔基的热致液晶性共聚酯的结晶形态

采用偏光显微镜、扫描和透射电镜从不同层次的结构水平上研究了含柔性间隔基热致液晶性共聚酯的结晶形态。在偏光显微镜下观察到典型的负光性球晶形态,透射电镜揭示了球晶是由厚度为10nm并沿着径向生长的片晶结构所组成,分子链沿晶片厚度方向取向排列。并研究了分子链的刚性程度对热致聚芳酯结晶性质的影响。结果表明,分子链刚性越大其结晶性和球晶的完善性越高。     

Experimental and numerical study of an aquaculture net cage with floater in waves and current

The mooring loads on an aquaculture net cage in current and waves are investigated by dedicated model tests and numerical simulations. The main purpose is to investigate which physical effects are dominant for mooring loads, and in this respect, to investigate the validity of different rational hydrodynamic load models. Also structural and numerical aspects are investigated. The model tests are performed to provide benchmark data, while the numerical model is used to study the effect and sensitivity of different load models and parameters.Compared to a realistic aquaculture plant, the total system is simplified to reduce the complexity. The system does, however, include all the four main components of an aquaculture plant: net cage, floater, sinker weights and moorings. The net cage is bottomless, flexible and circular. It is attached to a circular, elastic floater at the top and has 16 sinker weights at the bottom. The system is nearly linearly moored with four crow feet mooring lines.The loads are measured in the four mooring lines. A systematic variation of current only, wave only as well as combined current and wave conditions is carried out. The numerical simulation results are first benchmarked towards the experimental data. The mean loads in general dominate over the dynamic part of the loads in combined current and waves, and they significantly increase in long and steep waves, relative to current only. Next, a sensitivity study is carried out. A rigid floater significantly alters the loads in the mooring lines compared to a realistic, elastic floater. The theoretical model for the wave matters. The mooring loads are rather insensitive to a majority of the parameters and models, in particular: frequency dependent added mass of the floater and nonlinear restoring loads. It seems not to be necessary to represent the net cage with a very fine numerical mesh.