高效液相色谱紫外-可见光检测器参数设置对分析结果的影响

高效液相色谱仪仪器参数的选择不同可能对实验结果产生不同程度的影响。本文采用UV229型高精度紫外．可见光高效液相色谱检测器，研究仪器参数设置对分析结果影响的规律。所选择的仪器参数包括：狭缝宽度、响应时间和检测波长，通过检测限，线性范围和信噪比评价分析结果。结果表明：较大的狭缝宽度使检测器线性范围变差，但可以提高检测灵敏性，降低检测限。提高响应时间可以在一定程度上抑制基线噪声，但同时也使色谱峰峰高下降，色谱峰形变宽，对于早出峰组分影响尤其显著。对于不同的样品，选择合适的检测波长至关重要，不仅可以提高检测灵敏度，也可使线性范围增大。实际分析方法的建立，在仪器参数的选择上，可以根据分析目的对仪器参数加以调整，以达到理想的分析结果。     

Automated analysis of submicron particles by computer-controlled scanning electron microscopy

Automated analysis of submicron particles by computer-controlled scanning electron microscopy is generally possible. The minimum diameter of the detectable particles is dependent on the mean atomic number of the particles and the operating parameters of the scanning microscope. The main limitation with regard to particle size is set by the quality of the particle detection system, which generally is the backscatter electron detector. The accuracy of the results of the x-ray analyses is very often strongly affected by specimen damage, omnipresent especially for environmental particles even at low electron energies and probe currents. With the exception for light elements, the detection limit is approximately 1 wt%. Device-related limitations to automated analysis may be specimen drift and an unreliable autofocus function.     

A combined small- and wide-angle x-ray scattering detector for measurements on reactive systems

A detector with high dynamic range designed for combined small- and wide-angle x-ray scattering experiments has been developed. It allows measurements on single events and reactive systems, such as particle formation in flames and evaporation of levitating drops. The detector consists of 26 channels covering a region from 0.5° to 60° and it provides continuous monitoring of the sampled signal without readout dead time. The time resolution for fast single events is about 40 μs and for substances undergoing slower dynamics, the time resolution is set to 0.1 or 1 s with hours of continuous sampling. The detector has been used to measure soot particle formation in a flame, burning magnesium and evaporation of a toluene drop in a levitator. The results show that the detector can be used for many different applications with good outcomes and large potential.     

对电磁式地下金属管线探测仪零值测深法的改进

本文首先分析了沿用已久的电磁式地下金属管线探测仪零值测深法存在较大系统误差的原因，然后介绍了如何采用硬件措施和适当的数据处理方法达到提高测深精度的目的     

基于时序分析与神经网络的气阀机构故障诊断

通过模拟柴油机气阀机构的两种主要故障 :气门漏气和气门间隙异常进行实验 ,采集缸盖表面的振动信号。利用时间序列分析方法对振动信号建立AR和ARMA模型 ,利用其参数及残差等指标作为特征参数 ,提取时域的均方根等指标。最后利用人工神经网络进行故障模式识别。结果表明方法是可行的 ,效果较好     

Detection of atomic and molecular mega-electron-volt projectiles using an x-ray charged coupled device camera

We show that an x-ray charge coupled device (CCD) may be used as a particle detector for atomic and molecular mega-electron-volt (MeV) projectiles of around a few hundred keV per atomic mass unit. For atomic species, spectroscopic properties in kinetic energy measurements (i.e., linearity and energy resolution) are found to be close to those currently obtained with implanted or surface barrier silicon particle detectors. For molecular species, in order to increase the maximum kinetic energy detection limit, we propose to put a thin foil in front of the CCD. This foil breaks up the molecules into atoms and spreads the charges over many CCD pixels and therefore avoiding saturation effects. This opens new perspectives in high velocity molecular dissociation studies with accelerator facilities.     

Design and construct of a new detector for gas chromatography based on continuous negative corona discharge

In this work, a new detector was designed and constructed based on negative corona discharge. This detector can be used separately or as a detector in gas chromatography. The detector and chromatographic variables including cell temperature, gas flow rates, voltage between the two electrodes, and column temperature were optimized. Chloroform was used as a test compound to evaluate the performance of the detector. The detection limit of chloroform was obtained 0.78 ng∕ml and its dynamic range was over the range of 2-840 ng∕ml. The relative standard detection was about 6% for the limit of quantification. This detector is able to be used as an alternative for analysis of compounds containing electronegative elements.     

基于互相关检测和混沌理论的弱信号检测方法研究

本文简术了互相关检测的原理及混沌理论,在此基础上,提出了将互相关检测与混沌理论相结合检测微弱正弦周期信号的瓣方法。给出了原理框图、仿真模型及仿真实验结果。研究结果表明,此方法是目前信噪比门限较低的时域信号处理方法,因而具有广泛的应用前景。     

Limitation in obtainable surface roughness of hardened cement paste: ‘virtual’ topographic experiment based on focussed ion beam nanotomography datasets

Surface roughness affects the results of nanomechanical tests. The surface roughness values to be measured on a surface of a porous material are dependent on the properties of the naturally occurring pore space. In order to assess the surface roughness of hardened cement paste (HCP) without the actual influence of the usual sample preparation for nanomechanical testing (i.e. grinding and polishing), focussed ion beam nanotomography datasets were utilized for reconstruction of 3D (nanoscale resolution) surface profiles of hardened cement pastes. ‘Virtual topographic experiments' were performed and root mean square surface roughness was then calculated for a large number of such 3D surface profiles. The resulting root mean square (between 115 and 494 nm) is considerably higher than some roughness values (as low as 10 nm) reported in the literature. We suggest that thus‐analysed root mean square values provide an estimate of a ‘hard’ lower limit that can be achieved by ‘artefact‐free’ sample preparation of realistic samples of hardened cement paste. To the best of our knowledge, this ‘hard’ lower limit was quantified for a porous material based on hydraulic cement for the first time. We suggest that the values of RMS below such a limit may indicate sample preparation artefacts. Consequently, for reliable nanomechanical testing of disordered porous materials, such as hardened cement paste, the preparation methods may require further improvement.     

Fast response of InSb Schottky detector

An InSb Schottky detector, fabricated from an undoped InSb wafer with Hall mobility which is higher than those of previously employed InSb wafers, was used for alpha particle detection. The output pulse of this InSb detector showed a very fast rise time, which was comparable with the output pulses of scintillation detectors.     

高效液相色谱法测定动物组织中的莱克多巴胺残留量

目的：建立动物组织中莱克多巴胺残留量的高效液相色谱检测方法。方法：采用Symmetry C18色谱柱（4.6m×250mm,5μm）,甲醇-磷酸二氢钾溶液等度洗脱,流速1.0mL/min,检测器为二级管阵列检测器。结果：目标物保留时间约为6.1min,测定结果在0.1～10mg/L的范围内呈良好的线性（相关系数为0.9997）,RSD〈5.0%,检出限为10μg/kg,在猪肉样品中3个加标水平的平均回收率为78.1%～90.8%（n=3）。结论：该方法操作简单,灵敏度高,选择性好,符合兽药残留分析的要求。     

新型油液在线监测集成装置

油液在线监测是目前装备润滑磨损状态监测技术发展的重要方向,而监测仪器的开发是这一监测诊断技术研究热点。针对现代远洋船舶流动性工作特点及机械润滑磨损状态监测实时性要求,开发一套集油液磨粒监测和黏度检测的在线监测装置。装置具有结构紧凑、尺寸小、安装方便等特点。调试试验分析表明,该集成装置具有良好的稳定性,能快速实现油液磨粒含量、黏度趋势分析及超限报警。该油液在线监测装置的集成实现,为后续集成如水分、颗粒计数指标以及温度、压力等状态参数提供了研发基础。     

网状静电传感器弯管处颗粒速度与浓度的测量

为了对气力输送管道进行实时监控,并且提高炉膛内的燃烧效率,需要对气力输送管道中颗粒的速度与浓度分布进行测量。采用一种网状结构的静电传感器测量气力输送管道弯管处的颗粒速度与浓度分布。为了研究传感器的特性,首先建立了网状静电传感器的有限元模型。根据有限元仿真结果,优化网状静电传感器的设计,使其拥有更高更均匀的灵敏度分布,在实验室规模颗粒流实验平台上进行了实验研究。通过对上下游平面对应位置网状电极所得静电信号进行互相关运算,可以估测颗粒的轴向速度分布;通过对同一平面网状电极静电信号的均方根值进行重建,可以得到固体颗粒的相对浓度分布。实验研究表明,该网状静电传感器可以用来测量气力输送管道弯管处颗粒速度与浓度分布。     

转化法分析气体中的总硫含量仪器的研制

采用加氢转化炉,使气体中的硫化物在一定的温度条件下转化成硫化氢,用几种硫化物做转化率实验,根据这些数据说明可以用转化法较为简单地分析气体中的总硫.采用专门的自制色谱柱对硫化氢进行分离,用火焰光度检测器进行检测.在不使用转化炉时,可以随时装卸转化炉,维护方便,单独的微量硫分析仪还可以测其形态硫,使用较为灵活.仪器具有很高的可靠性和稳定性,检测限能达到0.05×10-6或0.02×10-6(以硫化氢计).     

海洋工程大型起重船力矩限制器的设计

根据8 000 t大型起重船的16点起重量-幅度表,对力矩限制曲线进行回归分析,利用最小二乘法拟合出起重机的力矩限制曲线。由于大型起重船臂架的变形使称重传感器输入输出呈现非线性的关系,用最小二乘法对称重传感器的输出进行了反非线性拟合,得到校正后的准确载重量。利用ARM7单片机实现设计思路,完成了系统的硬件电路和软件程序的设计,所设计的系统可以实现称重的准确测量,力矩限制的极限时可以自动报警并切断不安全方向的操作,起到保护的作用。     

Optimized acquisition parameters and statistical detection limit in quantitative EELS

Optimizing the acquisition parameters for EELS recording has to be accomplished simultaneously from the physical and the statistical points of view; the statistical aspect of the question is covered here. Approximate probability density functions of the variables of interest are derived, which provide a global measure of signal-to-noise ratio taking into account every step of the EELS edge area estimation process. Qualitative and quantitative advice is given regarding the critical choice of the estimation and integration energy regions. The notion of visual contrast is presented; it permits the introduction of the concept of statistical detection limit. It is found that for typical experimental conditions, when other factors are equal, the required analysis time for the sample varies approximately as the inverse square of the concentration.     

A method for estimating spatial resolution of real image in the Fourier domain

Spatial resolution is a fundamental parameter in structural sciences. In crystallography, the resolution is determined from the detection limit of high‐angle diffraction in reciprocal space. In electron microscopy, correlation in the Fourier domain is used for estimating the resolution. In this paper, we report a method for estimating the spatial resolution of real images from a logarithmic intensity plot in the Fourier domain. The logarithmic intensity plots of test images indicated that the full width at half maximum of a Gaussian point spread function can be estimated from the images. The spatial resolution of imaging X‐ray microtomography using Fresnel zone‐plate optics was also estimated with this method. A cross section of a test object visualized with the imaging microtomography indicated that square‐wave patterns up to 120‐nm pitch were resolved. The logarithmic intensity plot was calculated from a tomographic cross section of brain tissue. The full width at half maximum of the point spread function estimated from the plot coincided with the resolution determined from the test object. These results indicated that the logarithmic intensity plot in the Fourier domain provides an alternative measure of the spatial resolution without explicitly defining a noise criterion.     

锂离子电池外部短路电压行为预测模型评价

锂离子电池外部短路瞬间产生大电流引发安全事故频繁发生,精确的模型是风险预警的基础。围绕外部短路故障,从不同初始荷电状态(State of charge,SOC)、不同温度两方面开展了Thevenin等效电路模型与单粒子电化学模型的电压预测精度评价与复杂性对比。结果表明,Thevenin模型精度随初始SOC降低而下降,随环境温度升高上升;单粒子模型精度受初始SOC影响较小,随温度升高先上升后下降。针对Thevenin模型短路中精度下降等问题,提出了应用电感元件的模型优化方法。模型方均根误差小于60 mV,精度提升了76%;针对单粒子模型在外部短路大电流中精度变差的问题,提出了使用双电层放电和锂离子扩散限制进行建模的模型优化方法。模型方均根误差小于40 mV,精度提升了64%。优化后的模型分析结果表明：Thevenin模型实时性高,单粒子模型弥补了电池漏液时Thevenin模型的失效,但计算复杂;前者可用在外部短路的前期诊断和预警中,后者可用在外部短路发生后的热管理或热安全研究中。     

激光粒度仪的技术发展与展望

激光粒度仪是一种应用广泛的粒度测量仪器。本文介绍了激光粒度仪的测量原理,对激光粒度仪的技术发展包括光路系统的设计与优化、探测器及其他方面的改进作了概述。仪器的光学结构对其性能具有决定性的影响,光学结构的优化主要是为了扩展仪器的测量下限;采用不同的探测器则可以保证仪器的高重现性和全量程的高分辨率。文章最后展望了激光粒度仪的发展方向。     

某星载电子设备的动态响应分析

随机振动分析是星载电子设备动力响应分析的重要组成部分.通过对电子设备的实体模型简化处理,建立分析模型,利用有限元分析的方法获得随机振动载荷作用下设备各部位的加速度均方根值等系列响应值,为电路板器件布局优化,整机强度、刚度优化提供参考.进行了随机振动试验,实测典型位置的加速度均方根值,对有限元分析模型参数选择的合理性以及分析结果的准确性进行验证.