用锁相环路实现任意频率变换技术

介绍了锁相环路的工作原理以及MM74HC4046AN锁相环芯片的引脚功能，给出了利用锁相环进行频率变换的方法和用方波信号进行频率变换的实际电路，并对环路和相位进行了分析。     

聚(苯乙烯-丙烯酸)-氯化铜配合物催化引发丙烯腈聚合的研究

将聚(苯乙烯-丙烯酸)(PSAA)(Mw=3500)与氯化铜在异丙醇溶液中反应得到一种配位聚合物膜聚(苯乙烯-丙烯酸)-氯化铜(PSAA-Cu(Ⅱ)).研究丙烯腈(AN)在该配位聚合物膜、HSO3-和水体系(温度为55℃)催化引发作用下的聚合反应历程.AN在上述的催化引发体系中是按照自由基加聚反应历程进行聚合的,PSAA-Cu(Ⅱ)在催化引发体系中起着催化剂的配位催化作用.讨论了温度、Na2SO3浓度、AN浓度和PSAA-Cu(Ⅱ)膜用量对聚合速率、诱导时间的影响.实验结果表明,配合物PSAA-Cu(Ⅱ)膜催化引发AN聚合的诱导期为128s,反应24h后PAN产率为75.6%,Mw=2.18×104和Mn=1.12×104,多分散性系数为1.95.     

接入网发展中的相关热点问题分析

本文从电信企业建设发展的角度,分析了当前接入网建设所关注的热点问题如接入网一模块局、ＩＰ接入、ＨＦＣ、接入网网管建设,接入网与“九七工程”、接入网建设中提了后几百米等进行了分析,同时结合相关技术要求,提出了相应的发展策略。     

开展QC小组活动提高电阻涂漆工序合格率

本文介绍了利用QC小组开展活动,运用质量管理的理论和方法;提高电阻器生产过程中涂漆工序的合格率,降低了质量成本.     

QC活动增强企业核心竞争力

本文介绍富士通持续开展QC活动的实践,说明企业核心竞争力的源泉来自于品质改善.     

二阶一致无网格与有限元耦合离散研究

为准确方便地施加本质边界条件,在连续掺混法(Continuous Blending Method,CBM)的框架下,通过增加一个边中节点,发展了采用二阶基底的无网格与二阶有限元的耦合离散方法.Galerkin弱形式的数值积分采用具二阶一致性的3点积分方法(Quadratically Consistent 3-point integration method,QC3).与原本在QC3中采用的Nitsche法相比,所发展的耦合离散方法可像有限元法一样简单高效地施加本质边界条件,不向弱形式中引入额外项,也不依赖于任何人工参数.而且,数值结果还表明,QC3的计算精度也得到进一步提高.     

联合发端天线选择和收端人工噪声的物理层安全传输方法

该文在同频全双工技术快速发展的背景下,针对物理层安全研究中波束成形技术的高复杂度和发端天线选择(TAS)技术的低性能,提出一种联合发端天线选择和收端人工噪声(AN)的物理层安全传输方法TAS-rAN。首先,有多根天线的发端,利用天线选择技术,选取能使合法接收方接收信噪比最大的天线发送保密消息;其次,有同频全双工能力的收端,在接收到消息的同时,发送人工噪声来扰乱窃听方对保密消息的窃听。在Nakagami-m信道下,推导了安全中断概率的闭合表达式,并基于此,得到非零安全容量的概率表达式;通过渐进安全中断概率的推导,得到TAS-rAN方法的安全分集度。仿真结果表明,与已有的TAS-single和TAS-Alamouti方法相比,TAS-rAN安全方法具有较强的稳定性,且能提供更优的安全性能。     

Accuracy and precision in the determination of perfluorinated chemicals in human blood verified by interlaboratory comparisons

Perfluorinated chemicals (PFCs) are analyzed in laboratories worldwide to determine human blood levels and exposure pathways. The development of the analytical technique has been rapid in the last 10 years, and prerequisites for accurate and precise determination of PFCs in human blood at low ng/g concentrations are today readily available. The main contributing factors are the improved LC–MS instrumentations, the increased availability of native and mass labeled PFC standards, and new column materials available for chromatographic separations. The results of the first international interlaboratory study (ILS) in 2005 on PFCs revealed relatively better analytical results for human blood analyses when compared to analyses of a number of environmental matrices. The representative accuracy for the analyses of PFCs in human matrixes reported in recent years was established in the second human serum ILS in 2006. Interlaboratory standard deviations for the two human serum samples one low level concentration and one medium level concentration were found to be 12% and 16% for PFOS, respectively, and 47% and 21% for PFOA, respectively. Reported detections for all PFCs followed a frequency of PFOS > PFOA > PFHxS > PFNA > PFDA ? PFDoA ? PFDS ? PFHxA. Due to the small number of reported values for the other perfluorosulfonates and perfluorocarboxylates, standard deviations were not established.     

QC小组活动中的PDCA循环

PDCA循环（Plan／Do／Check／Act）,是美国统计学家戴明博士倡导并传播的,它反映了质量管理活动（计划、实施、检查、处理）的规律。近年来,日本等国家和地区,引导和帮助QC小组成员不断提升和培育自身“问题意识”,按照“显在、潜在、挑战”三个类别,明确地把握QC活动课题的性质,据此再选定适宜的过程方法,开展QC小组活动。文中就QC小组活动中PDCA循环的内在逻辑关系,QC小组活动在PDCA循环方面存在的不足等方面进行系统阐述,并对其结果进行了研究分析,提出关于PDCA循环新的思路。     

Structural evolution of poly(acrylonitrile‐co‐dimethyl itaconate) copolymer during thermal oxidative stabilization

The structural evolution of poly(acrylonitrile‐co‐dimethyl itaconate) [P(AN‐DMI)] copolymer was investigated by Fourier transform infrared spectroscopy (FTIR) in detail and compared with the polyacrylonitrile (PAN) homopolymer. The extent of cyclization reactions was calculated from the FTIR data. It was found that DMI comonomer had the ability to promote the cyclization reactions significantly at the temperature of 240°C, compared to the PAN homopolymer. The results of quantitative FTIR analysis in the range of 1000–1800 cm^?1 showed that the DMI comonomer not only promoted the cyclization reactions, but also facilitated the oxygen uptake reactions, especially the conjugated carbonyl group in an acridone ring in the ladder polymer chains, which proved that DMI comonomer had the potential ability to make successful thermal oxidative stabilization (TOS) process. The positive effects of DMI comonomer on TOS reactions and carbon yield were further confirmed by the dynamic thermogravimetry (TG) analysis. Copyright © 2015 John Wiley & Sons, Ltd.