Chemistry and Adhesive Properties of Phenylethynyl-Terminated Phenylquinoxaline Oligomers

As part of a program to develop high performance/high temperature structural resins for potential aeronautical applications, phenylethynyl-terminated phenylquinoxaline oligomers were prepared, characterized, thermally cured and the cured resins were evaluated as adhesives. The phenylquinoxaline oligomers were prepared by conventional and aromatic nucleophilic displacement routes and chain terminated with mono or di(phenylethynyl) groups. The oligomers were melt pressed into thin films, compression molded into tensile and compact tension specimens, and fabricated into titanium-to-titanium single lap shear adhesive specimens. The oligomers were generally compression molded for 1 hr at 350°C under pressures ranging from 0.10 to 1.4 MPa. The phenylquinoxaline oligomer prepared via aromatic nucleophilic displacement exhibited better processability and higher tensile shear strengths than those of the oligomers prepared via the conventional synthetic route. The synthesis, physical and mechanical properties of these oligomers and their cured polymers are presented.     

Plasma etching treatment for surface modification of boron-doped diamond electrodes

Boron-doped diamond (BDD) thin film surfaces were modified by brief plasma treatment using various source gases such as Cl₂, CF₄, Ar and CH₄, and the electrochemical properties of the surfaces were subsequently investigated. From X-ray photoelectron spectroscopy analysis, Cl and F atoms were detected on the BDD surfaces after 3 min of Cl₂ and CF₄ plasma treatments, respectively. From the results of cyclic voltammetry and electrochemical AC impedance measurements, the electron-transfer rate for Fe(CN)₆^3−/4− and Fe^2+/3+ at the BDD electrodes was found to decrease after Cl₂ and CF₄ plasma treatments. However, the electron-transfer rate for Ru(NH₃)₆^2+/3+ showed almost no change after these treatments. This may have been related to the specific interactions of surface halogen (C-Cl and C-F) moieties with the redox species because no electrical passivation was observed after the treatments. In addition, Raman spectroscopy showed that CH₄ plasma treatment of diamond surfaces formed an insulating diamond-like carbon thin layer on the surfaces. Thus, by an appropriate choice of plasma source, short-duration plasma treatments can be an effective way to functionalize diamond surfaces in various ways while maintaining a wide potential window and a low background current.     

用有限差分法分析多项式程序终止

针对多项式程序的终止性问题,提出了一种使用有限差分法判定其终止性的算法。以有限差分法的基本思想为基础,发现了程序循环条件表达式的值与其有限差分值之间的关系,并对其进行了严格证明,由此得到判定这类循环程序终止性的方法。最后,还进一步分析了使用有限差分法判定具有更复杂条件表达式和有多分支的循环程序的终止性。     

GPON系统中的动态带宽分配算法的研究

对GPON系统物理媒质控制（MAC）层的关键技术动态带宽分配（DBA）进行研究。提出了一种新的动态带宽分配（DBA）算法——基于QoS的二层动态带宽分配算法,并给出该算法的实现流程图。性能分析与对比表明,该算法可以提高网络的吞吐量,对不同用户和不同等级的业务都具有很好的公平性。     

高水平健美操运动员难度动作发展的新变化及对策分析?

基于健美操竞赛规则的变化,采用文献资料法、录像资料法、数理统计法和专家访谈法,对第10、11届世界健美操锦标赛决赛阶段前3名运动员的共348个难度动作的各项指标进行对比分析,结果表明:难度动作向着高分值变化是竞技健美操发展的一大趋势。     

基于MS-ECO的多模式多端角签收时序修复方法的研究

为了使现代超大规模数字芯片物理设计在签收阶段更快、更好地达到时序收敛,基于MS-ECO时序修复引擎,结合后端签收工具Tempus的精确度和后端实现工具Innovus的高效性,采用分布式多模式多端角时序分析,提出了一种跨平台签收阶段自动时序修复方法。在3个不同工艺的数字芯片上验证了该方法。结果表明,该方法平均能使时序违例路径减少86%,并使WNS降低72%,TNS降低89%。同时,该时序修复方法没有引入新的设计规则违例(DRV)。     

基于实例的煤矸石混凝土局部爆裂原因分析

针对某房屋楼板混凝土底部产生局部爆裂,且爆裂点出现不明黑色物质的现象,该文通过对现场情况的调查和取样测试分析,结合化学成分分析、X射线衍射分析、差热分析等相关数据,分析了产生爆裂的原因。研究表明,温度、湿度和接触介质变化导致煤矸石、蒙脱石等膨胀、崩解是楼板混凝土底部发生局部爆裂的原因,骨料中混杂煤矸石对混凝土外观、耐久性的潜在危害应引起高度重视。     

一种采用提前终止判决法的图像匹配跟踪算法

针对原始遍历式匹配模式算法的时间复杂度高以及给视频图像目标跟踪系统的计算能力带来极大考验的问题,提出一种基于提前终止判决的归一化互相关匹配算法(zero-mean normalized cross correlation based on early termination condition,ZNCC-ETC).在基于盒子滤波优化的遍历式ZNCC匹配算法(ZNCC based on Box-Filtering,ZNCC-BF)的基础上,发现ZNCC-BF算法在遍历匹配过程中存在着一个适当的阈值,一旦模板图与候选图的互相关累加值超过这个阈值,则后续任何计算即为冗余计算,而ZNCC-ETC则采用提前终止判决法实现图像的加速匹配跟踪,并通过对比实验进行验证与分析跟踪结果.分析结果表明:相对于标准ZNCC以及改进的ZNCC-BF,ZNCC-ETC算法能够在保证全局最大值收敛能力的前提下,进一步降低匹配过程中的计算量,实现加速匹配跟踪的目的.     

关于循环终止性证明的一种最小不动点方法

本文分析了循环终止性的特点,给出了实WHILE语句模型,简要地叙述了最小不动点理论,并结合到实循环函数上讨论了终止性的证明。