Effect of flow on solutions of rod-coil block co-polymers

An elongational flow field is imposed on a solution of block copolymers consisting of semirigid macromolecules with rigid, rodlike sequences of units in combination with random coil (flexible) units. The problem is formulated according to the lattice treatment of Matheson and Flory. In this formulation, the system consists of rigid blocks whose lengths and locations are fixed by the structure within each macromolecule. These blocks are separated by random coiled units. An excess free energy other than the equilibrium Gibbs free energy of the quiescent solution has to be considered due to the flow field that tends to align the rods. This excess free energy is calculated from the potential energy of rods when a steady-state, homogeneous and irrotational flow field is applied to the solution. The effects of composition, polymer-solvent interaction, size of the co-polymer and flow rates are investigated. Depending on the size and number of rods, some of the chains studied exhibit a biphasic region at equilibrium that shifts to lower concentrations with increasing flow. Longer chains with shorter rods that are isotropic at equilibrium, exhibit a biphasic region at finite values of flow. The degree of orientation increases sharply when the system is biphasic. For larger flows, the orientation function is very close to unity which is perfect orientation.     

机器人末端执行器姿态轨迹规划研究

研究了以四元数样条曲线作为插补曲线对机器人末端执行器姿态进行插补的相关算法,并进行了姿态轨迹规划。机器人末端姿态的表示方法一般有欧拉角、旋转矩阵等,但存在万向锁、插值困难等问题。引入四元数样条曲线,同时通过增加示教点,使四元数样条曲线适用于对机器人末端执行器姿态进行插补,并研究了基于S型的姿态轨迹规划算法,最后进行了多姿态示教点仿真实验。实验结果表明,所提出的算法规划出来的轨迹平滑,满足机器人末端姿态轨迹规划的要求。     

Real-time contactless measurement of robot pose in six degrees of freedom

For dynamically measuring position in three degrees of freedom laser tracking systems are well known. Up to now no possibility to measure also orientation using the same laser beam has been known. We present a technique to incorporate orientation measurement into a laser tracking system that requires only minor changes in the existing hardware. The method is based on the analysis of an image of the reflected laser beam intensity distribution. In this image the edges of a slightly modified retroreflector represent a function of the orientation of the end-effector holding the retroreflector. It is shown that from this image the orientation can be determined uniquely and in real time.

A laser tracking system including position and orientation measurement constitutes an instrument to accurately determine robot performance as well as to acquire hints on how to improve robot models and control algorithms.     

马来酸酐接枝聚丙烯纤维的结构和性能研究

采用熔融纺丝法制备了马来酸酐(MAH)接枝聚丙烯纤维,考察了接枝纤维的力学性能和吸湿率以及马来酸酐的残留量。结果表明,马来酸酐接枝聚丙烯纤维的断裂强度比纯聚丙烯纤维的低,接枝率越高强度越低,断裂伸长率则相反;随着接枝率的增加,纤维的取向度也逐渐升高。与聚丙烯纤维相比,接枝聚丙烯纤维的吸湿率有了明显提高,在相同拉伸倍数下提高了3-5倍;MAH残留量相当于接枝率(0.73％)的3.7％,表明主要是接枝的马来酸酐改变了聚丙烯纤维的性质。     

基于可视化SP法的滨水公共空间驻留偏好影响要素和开发 导向研究 — —以上海市黄浦江滨水区为例

驻留偏好可以衡量滨水公共空间的 品质。以黄浦江12个典型滨水公共空间为样 本,筛选要素类型和水平,建立理想模型,采 用可视化SP法,结合层次分析法和离散选择 模型,分析休闲步行者对滨水公共空间的驻 留偏好,得出关键影响要素和水平。结果显 示,高差过渡方式、文化设施配置、广场与 餐饮位置等偏好均与经验预判存在差异。因 此,以行为需求为基准,“自下而上”地从滨 水空间分配、水岸分界形式、驻留空间布局 和公建与设施配置等方面逐级提出开发导向,让滨水公共空间能够真正地契合实际行为需求。     

Synergetic improvement strategy on thermoelectric performance of CuAlO2 compacts

We fabricated Sr and Ca-doped CuAlO₂ compacts from the mixed powder of CuO, Cu₂O, Al₂O₃, and SrO or CaO by multi-pass hot pressing followed by spark plasma sintering (SPS). The XRD results showed the reaction of CuO, Cu₂O and Al₂O₃ was rather complete and only CuAlO₂ single phase was formed when the additive amount of SrO or CaO was appropriate. Multi-pass hot pressing increased the relative density and the usage of plate-like Al₂O₃ as reaction raw material enhanced the orientation degree. In spite of performance improvement conflicts through elemental doping, density increase and orientation improvement, the measurement on the thermoelectric performance indicated that the electrical resistivity, Seebeck coefficient, power factor, dimensionless figure of merit (ZT) were improved to varying degrees through the synergetic action of elemental doping, density increase, and orientation control. The highest power factor and ZT of the Ca-doped CuAlO₂ compacts reached 1.54?×?10^?4 W?m^?1 K^?2 and 0.015 at 973?K, respectively. The thermoelectric performance was higher than those of CuAlO₂ at the same temperature in published work before.     

扁丝及其编织品的几个工艺及设计问题探讨

本文讨论了扁丝生产几个工艺参数对扁丝性能的影响,并提出了扁丝及编织物的八个经验公式。     

应用型本科教育发展定位的思考

入世促使我国的高等教育更加开放地面向世界,也使我院人才培养面临新的机遇和挑战。本文分析了入世给我院发展应用型本科教育带来的机遇与挑战,研究了新形势下我院应用型本科教育的发展定位,在此基础上对我院发展应用型本科教育提出了建议。     

基于磁通门技术的方位传感器设计

磁通门技术是一种非电量磁测法，它利用由高磁导率、低矫顽力的软磁材料作成的铁芯在激磁作用下，感应线圈出现随环境磁场强度而变的偶次谐波分量电势的特征，然后通过高性能的滤波器测量偶次谐波分量。文中介绍了以磁通门技术为工作原理的方位传感器设计，主要包括磁通门的工作原理、铁芯的热处理工艺、二轴磁通门传感器的结构设计及电路原理。     

Photoluminescence and photoconductivity studies of oriented polyfluorene thin films

Photoluminescence and photoconductive properties of poly(9,9-dioctylfluorene) (F8) on rubbed polyimide (PI) alignment layers have been studied. The F8 thin films are highly oriented, which is manifested from polarized absorption, fluorescence, and photoconductivity spectra (the order parameter of F8 is 0.86). The ratio of photocurrent parallel to perpendicular directions to the rubbing direction (photoconductivity anisotropy) is 18 at 2.9 eV for F8. Effects of C₆₀ addition to F8 on the optical properties are also studied. C₆₀ addition to F8 significantly increases photoconductivity but decreases the order parameter (0.67) and the photoconductivity anisotropy (7 at 2.9 eV). Both F8 and C₆₀ doped F8 thin films exhibit similar photoconductive response and similar photoconductivity anisotropy (3-4) above 3.8 eV.