X荧光谱与人工神经网络相结合对陶片产地识别的研究

本文采用X射线荧光分析技术测量考古陶片中的微量元素,利用样品的元素种类和含量的不同对考古样本的产地进行智能化识别.针对多元素共存、计数率低等谱分析困难,采用人工神经网络方法对所测X荧光谱进行学习和识别.样本总数为48片,来自8个省份、20个采集地.用两种不同的网络结构分别对两类地域划分的陶片学习和识别,对准确产地分类的样本,产地识别率为100%;对其余样本,识别率大于60%.本方法的产地识别结果是可行的.     

质子X荧光分析在大气气溶胶研究中的应用(英文)

为了确定PIXE(质子X荧光分析)的测量准确性,进行了三个实验室的横向比对分析。比对中使用了30个单元素样品和一个多元素样品。结果显示,对于绝大多数样品,三家的一致性好于10％,三次测量的重复性相对于平均值好于6％。用一个自动的时间顺序步进采样器在北京采集了大气气溶胶样品,用PIXE对这些样品进行元素分析,然后对元素浓度数据用绝对主因子分析(APFA)进行统计分析,求出主成分以及它们解释的百分数。结果表明,PIXE与统计方法相结合可以有效地分解出城市大气气溶胶的主成分,并能将该地的和远地来的成分区别开来。用一个八级撞击式采样器在四个有代表性的地区进行了大气气溶胶采样,从由PIXE分析得到的一些代表性元素浓度的粒径分布特征,推断出大气气溶胶的来源。     

郊坛官窑瓷器的原料来源和着色机理研究

选取28个效坛官窑残片样品、1个效坛官窑遗址缸内泥料、1个练泥池内泥料、1个官窑所在地的紫金土样品和4个现代仿古官瓷的釉和胎样品进行中子活化分析，测定每个样品中36种元素的含量。将测量数据进行模糊聚类分析，得到动态模糊聚类分析图。结果表明：效坛官瓷胎和釉的原料来源明显不同，郊坛官窑有着稳定的釉料和胎料产地。铁是古官瓷釉的主要着色元素。用色彩分析仪测量古官瓷釉的反射光谱，确定了各种釉色的主波长；用穆斯堡尔谱测定釉中结构铁(Fe^2 、Fe^3 )的相对含量与各种釉色主波长之间的定量关系，从而揭示郊坛官瓷的着色机理。     

秦始皇陵三号坑兵马俑的模糊聚类分析

秦始皇陵兵马俑举世闻名，但其原料产地至今未明。选取秦始皇陵三号坑的陶俑和陶马样品44个，秦始皇陵兵马俑博物馆附近粘土样品20个，耀州瓷胎样品1个。用中子活化分析（NAA）测量样品中32种元素的含量，将这些数据进行模糊聚类分析，得到动态聚类分析图。结果表明：三号坑兵马俑样品与秦始皇陵附近的垆土关系极为密切，与秦始皇陵附近的黄土关系不太密切，与耀州瓷胎无关。由此推断兵马俑的原料可能取自骊山地区的某些垆土层，烧制兵马俑的窑址可能也在秦始皇陵附近。     

EDXRF方法测量菱镁矿中镁元素含量

采用间接测量的方法,对菱镁矿的化学分析过程进行处理,建立目标元素Mg与中间观测元素Ba之间的对应关系,以Ba的能量色散X射线荧光(Energy Dispersive X-ray Fluorescence,EDXRF)测量结果,计算出菱镁矿测试样品中镁的含量为29.43%,相对标准偏差为0.58%。借助于具有含量梯度的验证样品对方法的准确性进行了验证,得到的定标曲线具有良好的线性关系,测量结果显示准确度和可靠性高、稳定性和重复性好。该方法克服了EDXRF对轻元素直接探测效率低、结果精度差的缺点,为镁的测量提供了一种快速、准确、经济的检测思路和方法。     

反射型平衡辐射体装置的研制

在放射性同位素X射线荧光分析技术中,平衡辐射体装置是解决基体效应和邻近元素干扰的一种有效方法。本文介绍的装置专门用在样品中主干扰元素含量高于被测元素含量,同时主干扰元素的原子序数又略低于被测元素的场合。文章介绍了装置的原理、结构以及测定某铜矿铜精矿中铜元素的分析结果,相对误差≤4％者占样品总数的98％。     

景德镇与德化青花瓷原料来源的质子诱发X射线荧光分析

为了解景德镇和德化地区不同时期青花瓷的原料来源、成分和分类关系,用质子激发X射线荧光分析技术,分别无损测定34个样品胎、透明釉、青花釉中的主量化学组成,将所有样品的测量数据进行模糊聚类分析。结果表明:多数德化地区青花瓷胎样品和景德镇地区青花瓷胎样品的原料来源和分类关系明显不同;8个明代景德镇地区的青花瓷透明釉样品和多数德化地区青花瓷透明釉样品的原料来源和配方明显不同;除个别样品外,两地区多数青花釉样品分为截然不同的两大类,这为无损鉴别两地区青花瓷提供了一条重要的技术途径。     

水底沉积物原位X射线荧光测量中水分的影响与校正

论述了水底(海底、湖底或水系)沉积物中含水量的变化对原位X射线荧光测量的影响,以源初级X射线在沉积物上的相干散射线和非相干散射射线强度为内标建立的散射校正方程,可有效地克服沉积物中含水量变化对目标元素特征X射线的干扰。实验结果表明,对铜矿远景区土壤样品,当样品中含水量变化为20％时,目标元素(Fe：10．9％;Cu：300mg／kg;Zn：124mg/kg)特征X射线强度的变化小于5％。     

用核分析技术研究土法炼锌排入大气的颗粒物

用八级撞击式大气颗粒物采样器在我国南方的一个土法炼锌地区进行了大气颗粒物采样。用核分析——PIXE(Particle lnduced X-ray Emission)方法对样品进行了元素浓度分析,得到了十多种元素的质量浓度和粒径分布谱。对获得的浓度数据进一步作绝对主成分分析(APCA),获取颗粒物的主要来源成分和它们所占的比值。通过APCA与粒径分布谱的比较,发现三种粒径分布图像的组成元素与绝对主成分分析得到的三个主成分的强关联元素存在着良好的对应关系,由主成分所含有的特征元素,推出这三个主成分分别代表熔融矿石蒸气,土壤尘和煤燃烧物等。由元素质量浓度的粒径分布谱,用肺沉积模型计算了土法     

微束微区X荧光探针分析仪在矿石微粒分析中的应用

描述了一种微束微区X荧光探针分析仪,它采用会聚X光透镜来聚焦入射X射线,可对样品内微小面积的元素及其含量进行分析.以铁矿石内颗粒的测量为例,表明了微束微区X荧光探针分析仪是区分矿石中微小颗粒的有力工具,在细微材料成分分析和无损检测中具有广阔的前景.     

用ICP-AES法分析喂饲辐照食品的大白鼠血清中的微量元素

辐照保鲜是当前发展的一项新的食品保藏技术,其安全性为人们所关注。为此,近卅年来各国对辐照食品进行了大量的研究。结果证明经适当剂量辐照的食品是安全的。但随着生命科学的深入研究,揭示了某些微量元素对健康的密切关系,为此,测定辐照食品喂饲的大白鼠血清中微量元素的变化,以验证辐照食品的安全性。     

反应堆中子活化-多元素亚化学计量分离法测定生物和半导体材料中的Cu,Na,Au

近年来,由于Ge(Li)γ谱仪的普遍使用,亚化学计量分离法朝着多元素组分离的方向发展,亦可同时测定多种元素。 Elek和Kukala等人作了多元素亚化学计量组分离的理论研究,提出了关于MA_n类型的金属螯合物的多元素亚化学计量分离的关系式。如果指定:定量萃取(≥99％)金属离子M_i,同时保证亚化学计量(50％)萃取金属离子M_s,而金属离子M_1不被萃取,留在水相(≥99％);当等体积萃取时,有下述关系式:     

雪莲和珍珠的中子活化分析

用仪器中子活化法测定了５种不同产地的雪莲花和花茎中的３３种元素，对其不同产地和不同生长部位的元素含量进行了比较，还测定了天然珍珠、珍珠层及珍珠核中Ｉ、Ｆｅ、Ｚｎ等１４种元素，对不同部位的元素含量进行了比较分析。结果发现：不同产地的雪莲中大部分元素含量差别较大，从微量元素的角度说明中药材的地域性对其成分及药效的影响；雪莲和珍珠的不同生长部位其元素含量也不同，说明中药材的不同生长部位的药效也可能有差别     

Soil-to-Plant Transfer Factors of Stable Elements and Naturally Occurring Radionuclides: (2) Rice Collected in Japan

The critical paths of radionuclides and the critical foods in Japan are different from those in European and North American countries because agricultural products and food customs are different. Consequently, safety assessment in Japan is required to consider rice and vegetables as the critical foods. In this study, we measured soil-to-plant transfer factors (TFs) for rice using naturally existing elements as analogues of radionuclides under equilibrium conditions. Rice and associated soil samples were collected from 50 sampling sites throughout Japan and TFs of 36 and 34 elements for brown rice and white rice, respectively, were calculated on dry weight basis.

Probability distributions of TFs of elements for brown rice and white rice were a log normal type. Except for As and Mo, the TFs for brown rice were usually lower than those for wheat and barley especially for K, Fe, Sr (t-test: p < 0:05) and slightly lower than those for Ba, rare earth elements, Th and U. When the TFs of brown rice were compared with those of white rice, TFs of Th and U were higher in white rice, but, for many other elements, the TFs were lower in white rice than those in brown rice. Comparison of the data with previously reported values for Sr and Cs showed that the TFs of stable Sr and Cs were close to the respective values of fallout ⁹⁰Sr and ¹³⁷Cs observed in field experiments. Thus, the TFs of naturally existing elements can be used as TFs of those radionuclides which have been in contact with the environment for a long time and have reached equilibrium conditions.     

基于主元分析的小型压水堆故障检测和辨识方法研究

故障检测和辨识对于小型压水堆的安全经济运行具有重要意义。反应堆中通常采用基于信号和专家知识经验的故障检测和辨识方法,操纵员往往不能从海量的故障数据信息中及时准确甄别故障类型,追溯故障原因。本文提出了采用主元分析进行小型压水堆故障检测和辨识的方法。首先利用RELAP5程序对小型压水堆建模,获得典型故障的样本数据。其次,基于主元分析理论对样本降维,并计算T2和Q两个统计量,通过判断是否超出阈值来检测反应堆运行状态。然后,利用贡献率图方法分析了过程变量对于统计量的贡献率,从而确定了对故障特征变化起主要作用的变量,实现对不同故障的辨识。最终和实际物理过程分析结果进行对比,验证了该方法的有效性。      

微堆超热中子活化分析在地学样品测定中的应用

微型中子源反应堆(简称微堆)是以高浓铀(235 U)作燃料的轻水欠慢化型反应堆,辐照孔道内存在有较大份额的超热中子和快中子,适合进行超热中子活化分析(ENAA)的实验研究。地质样品成分复杂,在用普通的中子活化分析时,基体元素影响了部分元素的准确测定。为降低基体成分的本底干扰、改善目标元素的测量精密度和检出限,可采用超热中子活化分析的方法。本文利用微堆上安装的屏蔽材料为镉的超热中子辐照孔道,测定了元素周期表中67种元素的约130个核素的镉比,讨论了在超热中子活化分析中某些元素的有利因子及铀裂变和(n,p)反应的干扰情况,验证了微堆ENAA方法在地质科学样品检测中的实际应用,证实利用本方法可测定地学样品中20余种元素,其检出限、精密度和准确度均得到了较明显的改善。该法是常规活化分析方法必要的、有益的补充。     

Elemental and proximate analysis of coal by x-ray fluorescence assisted laser-induced breakdown spectroscopy

Although laser-induced breakdown spectroscopy (LIBS), as a fast on-line analysis technology, has great potential and competitiveness in the analysis of chemical composition and proximate analysis results of coal in thermal power plants, the measurement repeatability of LIBS needs to be further improved due to the difficulty in controlling the stability of the generated plasmas at present. In this paper, we propose a novel x-ray fluorescence (XRF) assisted LIBS method for high repeatability analysis of coal quality, which not only inherits the ability of LIBS to directly analyze organic elements such as C and H in coal, but also uses XRF to make up for the lack of stability of LIBS in determining other inorganic ash-forming elements. With the combination of elemental lines in LIBS and XRF spectra, the principal component analysis and the partial least squares are used to establish the prediction model and perform multi-elemental and proximate analysis of coal. Quantitative analysis results show that the relative standard deviation (RSD) of C is 0.15%, the RSDs of other elements are less than 4%, and the standard deviations of calorific value, ash content, sulfur content and volatile matter are 0.11 MJ kg−1, 0.17%, 0.79% and 0.41% respectively, indicating that the method has good repeatability in determination of coal quality. This work is helpful to accelerate the development of LIBS in the field of rapid measurement of coal entering the power plant and on-line monitoring of coal entering the furnace.     

The classification of plants by laser-induced breakdown spectroscopy based on two chemometric methods

The applications of laser-induced breakdown spectroscopy(LIBS) on classifying complex natural organics are relatively limited and their accuracy still requires improvement.In this work,to study the methods on classification of complex organics,three kinds of fresh leaves were measured by LIBS.100 spectra from 100 samples of each kind of leaves were measured and then they were divided into a training set and a test set in a ratio of 7:3.Two algorithms of chemometric methods including the partial least squares discriminant analysis(PLS-DA) and principal component analysis Mahalanobis distance(PCA-MD) were used to identify these leaves.By using 23 lines from 16 elements or molecules as input data,these two methods can both classify these three kinds of leaves successfully.The classification accuracies of training sets are both up to 100% by PCA-MD and PLS-DA.The classification accuracies of the test set are 93.3% by PCA-MD and 97.8% by PLS-DA.It means that PLS-DA is better than PCA-MD in classifying plant leaves.Because the components in PLS-DA process are more suitable for classification than those in PCA-MD process.We think that this work can provide a reference for plant traceability using LIBS.     

Calibrating the linearity between grayscale and element content for X-ray KES imaging of alloys

Doped elements in alloys significantly impact their performance. Conventional methods usually sputter the surface material of the sample, or their performance is limited to the surface of alloys owing to their poor penetration ability. The X-ray K-edge subtraction(KES)method exhibits great potential for the nondestructive in situ detection of element contents in alloys. However,the signal of doped elements usually deteriorates because of the strong absorption of the principal component and scatt...