Gasoline composition determined by H NMR spectroscopy

A fast and simple ¹H NMR spectroscopic method was developed for the concentration measurement of aromatic, olefinic and aliphatic fractions in gasoline samples. Simultaneously, individual components such as benzene, methyl tert-butyl ether and several dienes could be determined. The method relies on only a few, well-established assumptions about the molecular compositions and is therefore applicable to a broad range of gasolines. It is well suited for laboratories with high sample throughput since measurement time is short and all concentrations are determined within one NMR experiment. The method was applied to commercial gasolines and samples used in European round robin tests. Comparisons of NMR and round robin test results showed excellent agreement.     

基于Tx-Rx探头的异种金属焊缝缺陷检测及定量分析

异种金属焊接结构在使用过程中容易产生损伤,因此需对其进行检测;脉冲涡流一发一收式非同轴(Transmitter Receiver,Tx-Rx)探头可应用于异种金属焊缝缺陷检测;然而,考虑到异种金属焊接构件成分多样、结构复杂的特点,需对Tx-Rx探头的摆放位置进行了优化;首先,建立仿真模型,讨论了激励线圈的摆放位置对试件中涡流及涡流扰动的影响,结果表明,当激励线圈位于带堆焊的合金钢上方时,其表面涡流强度及涡流扰动强度较大;其次,建立实验平台,实验表明,当激励线圈放置在带堆焊的合金钢上方时,其检测信号幅值和差分信号幅值最大;最后利用差分信号的峰值对焊缝缺陷的定量展开分析;脉冲涡流Tx-Rx探头的研究可为其在异种金属焊缝缺陷的应用提供参考.     

ECOS电流检测技术应用分析

用电负载开启时,车载蓄电池的正极输出电流会发生变化,电流值通过智能电流钳进行测量,ICP的原理是使用补偿法的感应测量(霍尔效应)。这样的优势在于测量时不影响车辆的电流。电流钳通过蓝牙将电流数据实时传输给手持诊断仪,ECOS系统软件通过预设的参数,对电流数据进行统计分析,从而获得用电负载的工作电流,用于判断用电负载是否满足设计要求。     

Structural optimization of 2-D array probe for alternating current field measurement

A double U-shaped orthogonal inducer for the alternating current field measurement (ACFM) is presented, which could extend the limitation of the direction of tested cracks and decrease the loss of magnetic flux compared to the single rectangular inducer. The structure of the testing probe was optimized to meet the expectations of the pointwise magnetic field measurement and to decrease every group of coils’ space by orthogonally winding method, and the two-dimensional (2-D) ACFM probe array was designed. The detection precision and lift-off effect of the 2-D ACFM probe array were experimentally studied. The results show that the relative error of this probe is less than 10%, and it could suppress the lift-off disturbance effectively, which makes this 2-D ACFM probe array to be insensitive to lift-off and unable to meet the engineering expectations.     

螺旋焊管超声波探伤探头自动跟踪方式的发展

简要介绍了螺旋焊管超声波探伤中,探头自动跟踪方式的发展情况和各个跟踪方式的工作原理、系统构成及其存在的缺点。     

罐壁超声成像测厚系统的设计

介绍超声扫描成像技术在罐壁测厚中的应用。测厚系统采用多通道探头、PCI总线超声波界面卡和网络数据传输技术。这些技术的应用,提高了系统检测效率、检测速度、稳定性和可靠性。实际应用表明,该系统能进行100%壁厚测量,同时能满足检测精度和生产速度的要求。     

涡轮叶片专用探头研制与应用

介绍叶片专用探头设计原理，及其与SMART97型智能双频涡流探伤仪配套使用的情况，专专用探头在飞机发动机二级涡轮叶片探伤中具有良好应用前景。     

Kelvin Probe measurements of polymer coated gold substrates: Mechanism studies

The origin of work-function changes induced in polymer/metal structures (polyacrylic acid (PAA), ammonium and sodium polyacrylate) upon ammonia exposure is studied. To understand and explain the mechanism systematic measurements of uncoated and polymer coated metals are performed in Kelvin Probe (KP) setups. Additional data have been acquired through gravimetric and electrochemical experiments (cyclic voltammetry (CV)). The results obtained confirm that the field effect sensitive processes are taking place at the metal/polymer interface and allow their modelling. The intrinsic sensitivity of metallic samples upon ammonia exposure is influenced by the presence of coating polymers, by their ability to sorb water and to keep the metal surface wet or dry.     

Managing the degree of exfoliation and number of graphene layers using probe sonication approach

We have demonstrated a fast, versatile, and scalable approach to synthesize high-quality few layer graphene sheets with low defect ratio and high crystallinity produced from exfoliation of graphite flakes in DMF by using probe sonication. The effect of sonication time on degree of exfoliation and number of graphene layers has been fully investigated. The degree of exfoliation of graphene sheets as a function of sonication time has been successfully analyzed by XRD, UV-Vis spectroscopy, TEM, and BET studies. The morphological changes at different sonication times have also been observed by SEM. A structural and defect characterization of graphene sheets has been discussed in detail by Raman spectroscopic technique. The shift in position of 2D Raman band and its de-convolution provided information about formation of multi to few layer graphene sheets with sonication. Moreover, Raman results are highly consistent with TEM studies as per number of graphene layers is concerned.     

基于PGM模型的可用带宽度量算法评估

探测间隔模型(PGM)是负载小、速度快的可用带宽度量方法,但目前针对PGM的算法还缺乏系统、深入的评估。针对上述问题分析影响PGM算法精度的主要因素,提出端对端路径可用带宽的新型分类方法,选取PGM模型中较典型的Spruce和IGI算法,通过理论推导和仿真测试,评估不同背景流量类型等因素对算法精度的影响,为改进PGM模型的算法设计、提高算法精度提供参考。