基于超声无损检测对管道沉积物参数的分析

介绍了基于兰姆(Lamb)导向声波的对钢管中非对称沉积物体积参数的分析方法。通过收发分置的超声波换能器构建实验环境,分析散射曲线,获取合适的频率。最后利用该检测声波,使其在多个拥有各类体积参数沉积物的钢管内传播,进而通过换能器得到多组实验数据,并得出输出信号的幅值大小会随着沉积物体积的增加而减少的实验结果。     

193 nm激光引发PET表面的化学接枝

将聚对苯二甲酸乙二醇酯[Poly(ethylene terephthalate), PET]材料置于氨气气氛中, 利用激光光子同时激发材料表面及氨气形成自由基, 用激光引发反应并促进氨基在材料表面的接枝. 改性后的测试结果表明, 材料表面粗糙度没有显著变化, 但水接触角的减小表明表面化学结构发生了某种变化. 傅里叶变换红外光谱(FTIR/ATR)图谱在3352和1613 cm-1处出现了新的氨基吸收峰, 证实了表面接枝了氨基. 同时X射线光电子能谱(XPS)也证明了材料表面C—N键的存在, 其C1s结合能为285.5 eV, N1s为398.9 eV. 飞行时间二次离子质谱(Tof-SIMS)也检测到含氨基的分子碎片, 其碎片成像图显示接枝仅发生在激光辐照部位. 实验结果表明, 激光能在生物材料表面进行局部区域的选择性接枝.     

ACTS AERONAUTICAL EXPERIMENTS

This paper discusses a series of aeronautical experiments that utilize the advanced communication technology satellite (ACTS). As part of the ongoing effort to investigate commercial applications of ACTS technologies, NASA's Jet Propulsion Laboratory and various industry/government partners have developed a series of experiments that utilize the ACTS mobile terminal (AMT)¹ and the broadband aeronautical terminal¹ to investigate aeronautical uses of the ACTS. This paper discusses these experiments including the experiment configurations, technologies, results and future implications.     

A summation due to Ramanujan revisited

We employ Hardy’s regularly convergent double series to refine an argu- ment of Nanjundiah [7]. In particular, we evaluate some alternating series.     

Comments on: ’Non-symmetrical coupled lines in an inhomogeneous dielectric medium’

Many magnetic multi-level counters count in an upward sequence, but not in reverse sequence, and the counting cores have readouts in the form of analogue displays. This paper shows how to construct a reversible decimal counter with a non-destructive read-out by a toroidal core.     

考虑声誉效应的众包竞赛动态激励机制研究

将声誉效应引入众包竞赛的激励机制可以促使接包方为考虑未来绩效收益而提高当前努力。建立并求解了显性和隐性声誉效应下连续两个任务阶段的动态激励模型,探讨了显性声誉修正系数、隐性声誉系数以及参赛者数量对激励效果的影响,并与无声誉激励机制进行了对比。研究表明,声誉激励机制通过单位绩效激励强度和固定奖励水平两条途径起作用,增大隐性声誉系数有助于提高每个任务阶段的努力程度,显性声誉不确定性则会降低第2任务阶段的努力程度;各种条件下实施声誉激励对第1任务阶段中的努力程度和单位绩效奖励的影响存在不确定性;参赛者数量的增加有助于弱化第1任务阶段中棘轮效应,但也会降低声誉激励机制对努力程度的正向价值,扩大声誉激励机制对单位绩效奖励的负向价值。