矿样中钛铁EDXRF分析的基体效应和神经网络校正研究

用能量色散X荧光(EDXRF)分析仪测量钛铁矿样时,存在基体效应影响分析准确性的问题.本文用EDXRF测得钛、铁元素特征峰,通过类Gauss函数对实测谱进行拟合分解,初步分析了矿样中Ti-Fe间的影响特征.针对各元素计数率与含量的非线性关系,采用先分类后预测的方法,首先用SOFM自适应神经网络对矿样分类,样本总数80组,对铁精矿、钛精矿的识别率为100%;然后用RBF神经网络进行钛铁含量预测,与化学分析结果对比,其中65.4%的样品相对误差在1%以内,其余均在3%以内,小于工业生产仪器分析相对误差5%的要求,表明基于先分类后预测的神经网络校正技术在矿样元素含量分析中有着一定的实用价值.     

铁矿浆品位在线分析系统的研制

利用双能量γ射线吸收法成功研制了铁矿浆品位在线检测仪.该检测仪可用于铁矿石处理工艺中对矿浆铁品位进行在线检测和控制.矿浆浓度、粒度变化对品位测量的影响很小,品位测量误差小于0.5%,射线计数率的长期稳定性＜0.05%.此方案对工业现场条件有较好的适应性.     

铁矿浆品位在线分析系统的研制

利用双能量γ射线吸收法成功研制了铁矿浆品位在线检测仪.该检测仪可用于铁矿石处理工艺中对矿浆铁品位进行在线检测和控制.矿浆浓度、粒度变化对品位测量的影响很小,品位测量误差小于0.5%,射线计数率的长期稳定性＜0.05%.此方案对工业现场条件有较好的适应性.     

某复杂稀土矿湿式电磁选与超导磁选预富集试验研究

为考查内蒙古某复杂多金属矿中稀土矿物的磁选预富集效果,本文采用常规湿式电磁选和超导磁选两种磁选方式,开展了系统的试验研究,结合X射线衍射仪(XRD)、振动样品磁强计(VSM)和扫描电镜(SEM)测试等手段,对预选产品进行了分析和表征。结果表明：与湿式电磁选“一粗一扫”流程的分选效果相比,超导磁选工艺经过一次粗选可获得抛尾率为66.74%、精矿稀土氧化物(REO)品位为2.855%、REO回收率为92.82%的预选指标。XRD、VSM和SEM分析结果表明,稀土矿物经超导磁选可获得高效预富集,超导磁选精矿比磁化系数最大值达4.299×10^-6 m~3/kg,磁性略强于湿式电磁选精矿产品,具有高背景磁感应强度优势的超导磁选可有效回收解离不完全的稀土矿物弱磁性贫连生体,实现REO的高效预富集。     

精矿矿浆中子活化在线分析

在实验室条件下采用中子活化分析中的相对分析法测量了金川金属公司所提供的精矿矿浆样品中铁、硫、硅、镁、铜、钴、镍、钙8种元素的含量,其测量结果与化学分析方法所得结果相比,分析精度和准确度更好.这就为精矿矿浆的实时在线分析系统提供实验基础.     

基于丝壁电离室的数字化氚在线测量系统的研制

涉氚场所中的氚浓度在线测量是保障工作安全顺利进行的有力条件。针对涉氚场所中氚主要以氚气形式存在的特点,设计并研制了一套数字化氚在线测量系统。该系统采用补正极原理设计了丝壁电离室,消除了氚在进入电离室前产生的电离离子对测量结果的影响;开发了数字化信号处理系统,可自控获取、处理及显示过程中的氚浓度。系统在氚靶生产过程中得以应用,结果表明,丝壁的设计使得电离室室壁氚吸附产生的记忆效应减小到1%以内,系统中的氚浓度能够在线实时准确测量、显示,能很好地满足涉氚场所氚在线测量的要求。     

BIXS技术测量氚化钛膜氚活度实验方法研究

完成了BIXS能谱测量系统的组建及调试,对BIXS技术测量氚化钛膜氚活度的实验方法进行了研究。实验获得了空气和Ar气介质中的X射线能谱,与空气介质相比,除有两个相同峰位能量为4.5 keV和5.0 keV的谱峰和峰强度(或峰面积)分别减弱至约为0.4%、1%外,还增加了3.0 keV、9.0keV的两个谱峰;同时获得了不同氚活度氚化钛膜的X射线能谱,结果表明氚活度决定着X射线能谱的峰面积,具有良好的线性关系。     

X射线CCD式电缆偏心在线检测装置的研制

基于X射线CCD的电缆偏心在线检测改进技术大大提高了检测装置的测量精度和响应速度.文中介绍了X射线CCD应用于电缆偏心在线检测系统的检测原理和-个检测装置的结构,该装置硬件由扫描驱动系统、X射线发生器组件、数据采集部分和高性能计算机系统组成.给出了该装置在实际运行中的效果,以及与其他电缆偏心检测技术的特点比较.     

Monte Carlo法在检测浮选矿物品位中的应用

采用Monte Carlo法产生矿粉样品的XRF谱,对30个矿粉样品的品位进行了分析,结果表明该方法能够对浓度值为百分之几及其以上的元素进行有效分析。还对影响分析效果的各种因素进行了讨论,结果表明学习谱的个数越多,标准样品浓度分布范围越广,分析结果越精确可靠。此方法分析速度快,可以用于对矿物品位进行在线分析。     

脉冲X射线波形采集和剂量分析系统电子学设计

介绍了一种脉冲X射线波形采集和剂量分析系统。该系统采用Cs I耦合Si PD探测器,通过FPGA控制高速ADC快速采样脉冲X射线波形,实现在线实时分析X射线波形参数;通过与热释光探测器相互配合,实现单脉冲波形与剂量数值的可靠传递。经试验验证,脉冲X射线波形采集和剂量分析系统能够实现X射线波形的快速采集、实时分析和剂量传递,具有灵敏度高,一致性好等优点。     

EDXRF中吸收增强效应实验的指数刻度方法初探

针对EDXRF技术分析矿石中铁元素含量问题,提出了一种新的刻度方法。利用EDXRF分析技术得到了钛、钒、镍、铜、锌对铁元素的吸收增强效应。结果表明,Fe元素Kα系X射线的归一计数率（RFe）与含量（WFe）之间的关系表现为双曲线形式。根据前期研究结果,建立了一种基于最小二乘回归算法的指数拟合工作曲线刻度方法,同时实现了对基体效应的有效校正。通过对3种铁矿石中铁元素含量计算结果表明,与传统的多元回归刻度方法相比,指数刻度方法有较好的计算结果。     

Coating of Titanium Nitride on Stainless Steel Targets by a 4?kJ Plasma Focus Device

Titanium nitride thin films were deposited on stainless steel (SS316L) targets by using a 4?kJ plasma focus device. The corresponding energy flux delivered to SS316L surface is estimated to be 2.69?×?10¹³?kev?cm^?3?ns^?1. X-ray diffraction analysis reveals the formation of a nanocrystalline titanium nitride coating on the surface of targets. Thickness of the elements found on the surface of treated samples which are obtained by Rutherford backscattering spectrometry analysis (RBS) were (×10¹⁵ at/cm²) .45% Ti, 50% N and 5% Fe. Scanning electron microscopy was used to indicate changes in surface morphology. Existence of grains in different size confirms the formation of TiN crystals on the surface of targets.     

55Fe effect on enhancing ferritic steel He/dpa ratio in fission reactor irradiations to simulate fusion conditions

This study evaluated methods for increasing the helium production rate in ferritic steel irradiation in a fission reactor neutron spectrum in order to increase the helium to atomic displacement ratio to values typical of fusion reactor first wall conditions. An early experiment showed that the accelerated He(appm)/dpa ratio of about 2.3 was achieved for 96% enriched ⁵⁴Fe in iron in the High Flux Isotope Reactor (HFIR), ORNL. In the current work, the ferritic steel He(appm)/dpa ratio was studied in the neutron spectrum of HFIR with the ⁵⁵Fe thermal neutron helium production taken into account. A benchmark calculation for the same sample, as used in the aforementioned experiment, was then used to adjust and evaluate the ⁵⁵Fe (n, a) cross section values in TALYS-based Evaluated Nuclear Data Library (TENDL). The analysis showed that a decrease of a factor of 6700 for the TENDL ⁵⁵Fe (n, a) cross section in the intermediate and low energy regions was required in order to fit the experimental results. The best fit to the cross section value at thermal neutron energy was about 27 mb. With the adjusted ⁵⁵Fe (n, a) cross sections, calculation showed that the ⁵⁴Fe and ⁵⁵Fe isotopes could be enriched by the isotopic tailoring technique in a ferritic steel sample irradiated in HFIR to significantly enhance the helium production rate. This new calculation can be used to guide future isotopic tailoring experiments designed to increase the He(appm)/dpa ratio in fission reactors. A benchmark experiment is suggested to be performed to evaluate the ⁵⁵Fe (n, a) cross section at thermal energy.     

ESR Dosimetry of Teeth of Residents Close to Chernobyl Reactor Accident

Sorption behavior of uranium (VI) during crystallization of amorphous iron (A.Fe) minerals to crystalline iron (C.Fe) minerals have been investigated. Two different sorption conditions are applied for the experiments. One is the condition in which uranium is sorbed on A.Fe minerals before the crystallization (dynamic condition). The other is the condition in which uranium is sorbed on the A.Fe minerals and C.Fe minerals of goethite (static condition). Associations of uranium with the iron minerals are examined by a selective extraction test using a 1 M CH₃COOK solution at pH 7, 1 M CH₃COONa solution at pH 5 (Morgan's solution), and TAO solution (10.9g.l^?1 oxalic acid+l6.1g.l^?1 ammonium oxalate).

Under the static condition, the fraction of uranium desorbed by a 1 M CH₃COOK solution at pH 7 from A.Fe minerals is lower than that from goethite. And all of uranium are desorbed by the TAO solution from both A.Fe minerals and goethite. Contrary, under the dynamic condition, fractional uranium is remained after the TAO solution extraction. The fractional uranium remained after the TAO solution extraction from the iron minerals increases with increase in the crystallinity of the iron minerals. The concentrations of uranium in the solutions are less than 1%. These show that during the crystallization of amorphous to crystalline iron minerals most of uranium associated with the amorphous iron minerals is not released into the solution, and some fractional uranium move to be fixed to crystalline iron minerals.     

Analysis and evaluation of thermal and resonance neutron activation data

A generalized least-squares technique has been applied to produce a consistent set of thermal and epithermal neutron activation data for the following 20 nuclides produced by neutron capture: ⁴⁶Sc, ⁵¹Ti, ⁵¹Cr, ⁵²V, ⁵⁶Mn, ⁵⁹Fe, ⁶⁰Co, ⁷⁵Se, ⁸⁶Rb, ⁹⁵Zr, ⁹⁷Zr, ¹²⁴Sb, ¹³¹Ba, ¹³⁴Cs, ¹⁴⁰La, ¹⁴¹Ce, ¹⁶⁰Tb, ¹⁸¹Hf, ¹⁸²Ta and ¹⁹⁸Au. The technique combines available information on nuclear data from the literature with measured activation data irradiated in nine reactor positions in Germany, the U.K. and Japan.Most of the solution nuclear data showed a distinct improvement, some by a large amount. These have been compared with the most recent evaluation.     

Application of On-Line Digital Noise Analysis to Reactor Diagnosis in JMTR

The reactor noise analysis technique is particularly useful in reactor diagnosis for on-line monitoring if the raw noise signals can be processed in almost real time.

An on-line reactor noise analysis system has been developed with use made of the mini-computer HITAC-10. This system utilizes functions for calculating the power spectral density in almost real time, plots the output by digital incremental plotter, and displays the results by means of color graphic display equipment, in order to detect anomalous reactor conditions with the statistical technique.

Using this system, reactor noise signals have been measured and analyzed under various operational conditions in the JMTR. The variance of the power spectral density is found to fit a logarithmic probability density function. This function is independent of the frequency, but is dependent on the number of sampling functions.

A logical procedure for anomaly detection based on statistical characteristics has been developed. It is applied to a case where it is supposed that the PWR operating mode in the OWL-1 is the normal process and that the BWR mode is the anomalous. It is demonstrated as a result, that this procedure can successfully detect anomalous processes.     

遗传算法优化的BP神经网络在EDXRF中对钛铁元素含量的预测

在能量色散X荧光分析(EDXRF)技术中,受均匀效应、颗粒效应和基体效应等的干扰,定量分析精度受到影响。本文针对这一问题提出了遗传算法(GA)优化BP神经网络(GA-BP)的混合算法,该算法无需考虑元素浓度和射线强度之间的复杂关系。遗传算法优化BP神经网络的目的是为了获得更好的网络初始权值和阈值,其基本思想是:将初始化的BP神经网络均方根误差的倒数编码为遗传算法中个体的适应度;初始的权值和阈值用遗传算法中的个体代替,然后通过选择、交叉和变异操作挑选出最优个体,最后通过解码用最优的权值和阈值创建一个新的BP网络模型。攀枝花矿区5类矿样中钛和铁含量的整体预测和分类预测实验表明,分类预测效果远好于整体预测。预测值与化学分析值比较结果表明,其中76.7%的样品相对误差小于2%,表明了该方法在元素间基体效应校正上的有效性。     

Study of Syrian archaeological pottery by the combined application of thermoluminescence (TL) dating, X-ray fluorescence analysis and statistical multivariate analysis

X-ray fluorescence method and the technique of thermoluminescence (TL) dating have been utilized for the study of archaeological pottery fragment samples, fairly representative of the Romanian period between 1st century B.C. and 4th century A.D., from Judaidet Yabous site, which is located north-west of Damascus city, Syria. Four samples were chosen randomly among the 46 samples for dating using thermoluminescence technique and the results were in good agreement with the date assigned by archaeologists. The samples were irradiated for 1000 s live time twice, first using a Mo X-ray Tube and second using a ¹⁰⁹Cd radioactive source. Fifteen elements (K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, and Pb) were determined. The elemental concentrations have been processed using two multivariate statistical methods. The purpose of the study was to characterize by means of element contents of the pottery paste from the Judaidet Yabous archaeological site and to provide new data to the Syrian databases for future studies. From an archaeological point of view the results indicated that most of the potteries were locally produced.