基于BBO算法的WSN覆盖与连接节点部署方案

针对无线传感器网络中目标节点部署能力差的问题,提出基于生物地理学优化(biogeography-based optimization,BBO)算法的节点部署方案,该方案能够在网络中找到满足K-覆盖和M-连通性要求的传感器节点最佳部署位置。提出的基于BBO的算法为目标节点提供了一种有效的编码方案,通过优化构建的加权多目标函数来获得近似最优解,选择最小数量的合适点P,使得所有目标点在满足K-覆盖的同时,覆盖目标的传感器节点也满足M-连接。仿真结果表明,该方案能够在不同的K和M组合下找到合适位置的最优数,而且与其他技术方案相比,该方案的性能具有明显的优势。     

Mechanisms linking employee affective delivery and customer behavioral intentions.

Past empirical evidence has indicated that employee affective delivery can influence customer reactions (e.g., customer satisfaction, service quality evaluation). This study extends previous research by empirically examining mediating processes underlying the relationship between employee affective delivery and customer behavioral intentions. Data were collected from 352 employee-customer pairs in 169 retail shoe stores in Taiwan. Results showed that the influence of employee affective delivery on customers' willingness to return to the store and pass positive comments to friends was indirect through the mediating processes of customer in-store positive moods and perceived friendliness. The study also indicated that employee affective delivery influences customers' time spent in store, which, in turn, influences customer behavioral intentions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of fluoride contamination on the growth of ZrO2 films

The mechanism by which fluoride ion degrades the oxide film on Zircaloy-2 has been investigated by deliberately contaminating specimens. Delaying the washing of specimens for 0, 60 and 1800 s after pickling gave sets of, respectively, well-pickled, poorly-pickled and pickle-stained specimens. These were oxidised initially in dry steam (300°C, 3.5 MPa) and were then transferred to water (300°C) for short periods (1, 2 or 7 days). The oxides produced were examined by weight gain, interferometry, impedance spectroscopy and optical, SEM and TEM microscopy. The initial oxidation rates in steam were little different for the three groups of specimens (1 or 2 days), although the interference coloured oxides showed a very different distribution of oxide thicknesses between the well-picked specimens and the other groups. Transfer to water rapidly resulted in thick, friable, porous oxides on the pickle-stained, but not the other specimens, that could not be examined by many techniques because of ready loss of oxide. The techniques that could be applied to these specimens showed that they consisted of apparently large oxide crystallites in multiple layers nearly normal to the oxide metal interface. The original surface topography was still visible in areas where this surface had not spalled, showing that the degradation occurred within the oxide. The severity of this attack was determined by the extent to which the original preparation technique had left oxyfluoride layers on the initial surfaces. It was deduced that these oxyfluoride layers developed porosity in which concentrated fluoride solutions could form during high temperature exposures in water. These solutions attacked the ZrO₂ film by hydrothermal dissolution and recrystallisation to give the large layered platelets in the degraded films. The oxyfluorides appear to be sufficiently hygroscopic that the same degradation process occurred generally in 300°C, 3.5 MPa steam, only locally in 0.1 MPa steam and not in moist air.