基于图像小波包信息熵和遗传神经网络的气-液两相流流型识别

根据小波包变换能够将图像信号按不同尺度进行分解的特性,提出了基于图像小波包信息熵特征和遗传神经网络相结合的气-液两相流流型识别的新方法.该方法采用高速摄影系统获取水平管道内气-液两相流的流动图像,经过处理,对图像进行多分辨率分析,提取小波包变换系数的信息熵特征,用主成分分析法降低特征维数构成特征矢量,作为流型样本对遗传神经网络进行训练,实现了对流动图像的流型智能化识别.结果表明:图像小波包信息熵特征可以很好地反映各流型之间的差异;遗传神经网络结合遗传算法和BP算法各自优点,具有收敛速度快、不易陷入局部极小的特性,网络识别率为100%.     

基于BP神经网络的核探测器故障诊断方法研究

核探测器是核设施放射性监测的重要设备,为了保障该设备的持续稳定运行,本研究针对闪烁体探测器提出了一种基于BP神经网络的在线智能故障诊断方法。采用小波包变换将探测器输出信号从时域变换至频域后提取特征向量,将得到的特征向量作为BP神经网络故障诊断模型的输入,再通过误差梯度下降法对该模型的参数进行优化,最终利用最优的诊断模型完成故障类型的智能识别与分类,并将该方法与统计诊断方法和基于支持向量机的故障诊断方法进行横向的对比研究。研究结果表明,新方法的平均诊断准确率均优于上述两种方法。因此,该方法的应用能有效地提高核探测器的故障诊断准确率。     

基于评价函数和BP网络的CRDM滚轮状态评估方法

针对采集的控制棒驱动机构（CRDM）振动信号中存在非平稳、强噪声失真信号,提出一种基于评价函数和误差反向传播（BP）网络的CRDM滚轮状态评估方法。信号经半软阈值去噪、局部均值分解（LMD）提取特征向量,特征向量组成的样本集经BP网络进行状态识别,引入评价函数对状态识别结果进行评价,依据评价结果进行失真样本剔除,保留新形成的样本集进行状态识别。结果表明,基于评价函数和BP网络的CRDM滚轮状态评估方法能有效对滚轮缺陷状态进行识别,解决了控制棒驱动机构滚轮状态难以进行准确识别的问题。      

一种基于BP神经网络的γ能谱识别方法

从军控现场核查过程中敏感信息保护的目的出发,对利用BP神经网络技术通过γ能谱识别核部件类型的方法进行了初步研究.实验时识别正确率达到98%以上,说明利用神经网络技术识别核部件是一种切实可行的方法.     

基于核探测器信号波形特征的故障诊断研究

核探测器是一种特殊的随机信号转换器,发生故障时,采用传统的人工方法很难及时有效地对故障进行诊断。本文提出了一种针对闪烁体探测器信号波形特征的在线智能故障检测与分类方法,通过分析闪烁体探测器不同故障时的输出信号变化特征,建立了相应的故障模型。使用小波包算法与支持向量机理论分解并提取特征向量,即可判断故障类型。以ST401闪烁体探测器为例,进行了模拟仿真实验。实验结果表明,基于信号波形特征的数字化方法能快速有效地对闪烁体探测器进行故障自动诊断。     

基于核探测器信号波形特征的故障诊断研究

核探测器是一种特殊的随机信号转换器,发生故障时,采用传统的人工方法很难及时有效地对故障进行诊断。本文提出了一种针对闪烁体探测器信号波形特征的在线智能故障检测与分类方法,通过分析闪烁体探测器不同故障时的输出信号变化特征,建立了相应的故障模型。使用小波包算法与支持向量机理论分解并提取特征向量,即可判断故障类型。以ST401闪烁体探测器为例,进行了模拟仿真实验。实验结果表明,基于信号波形特征的数字化方法能快速有效地对闪烁体探测器进行故障自动诊断。     

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.     

基于能量分布特征的地震事件自动识别

研究了地震信号在小波包变换下的特性,依据地震事件识别中“历史事例对比法”的思想,根据不同震源地震信号频率时变特性的不同．提出了基于“能量分布特征”的特征值,同时采用该特征值用神经网络方法对地震事件进行识别分类。该方法不依赖于系统的数学模型,而是直接利用各频率成分能量的变化提取特征值作为神经网络的输入特征向量来进行事件的识别,避免了对地震信号、传播途径准确建模的困难,简便、直观地完成了事件的识别。实验证明,该方法的事件识别率可达到99％以上．是一种有效的地震事件识别方法。     

基于小波包变换的地震事件分类

研究了地震信号在小波包变换下的特性,依据地震事件识别中“历史事例对比法”的思想,根据不同震源地震信号频率时变特性的不同,提出了基于“能量—事件”的地震事件分类方法。该方法不需要系统的模型结构,而是直接利用各频率成分能量的变化来进行事件识别,避免了对地震信号、传播途径准确建模的困难,简便、直观地完成了事件的识别。采用统计方法对实验样本进行处理,分别拟合出某地震台站记录的某地区天然地震、核爆炸事件的特征值和容差范围,并据此对检验信号集进行了检验,实验证明,该方法的事件识别率可达到95％以上。     

基于SVM和DWT的辐射图像局部特征识别方法

针对辐射图像的特点,设计并开发了一种支持向量机（SVM）和基于离散小波变换（DWT）的局部特征识别方法。使用支持向量机解决了辐射图像局部特征提取的困难和分类器对样本数目的要求。而小波的应用使得该算法能够支持多分辨率的特征提取,并提高了总体识别效率。还对比了两种常见的核函数,实验结果表明高斯径向基函数能够取得比较好的分类效果。     

Sorption methods of separating barium and radium,aluminum and gallum,and zirconium and hafnium

Chromatographic methods of separating elements with very similar properties have now been developed. However, a number of these methods are difficult to use industrially as their throughput is low. The efficiency of chromatographic separation methods could be increased considerably by using appropriate complex formers, which decrease the effective concentration of the ions being separated, and,in the first approximation, this is equivalent to a decrease in the amount of elements being separated. The difference in the formation constants of the complex compounds increases the separation coefficient. By investigating chromatographic separation with the use of various complex formers, we found the optimal conditions for separating barium and radium, zirconium and hafnium, and aluminum and gallium. The throughput of these methods, with respect to the macroelement was 15–60 kg/hr per m² of column cross section.     

医源性电离辐射损伤及其生物医学防护

随着核与辐射技术在医学检查、诊断和治疗领域运用的增加,世界范围受照人群不断增多,医源性辐射已成为人类最主要的人工辐射来源之一。医疗机构和个人在选择利用放射手段获取诊断和治疗利益的同时,需要注意和防护伴随的辐射损伤效应。本文介绍了医源性辐射及其危害、机体组织的辐射损伤特性和类型、辐射生物效应分子及效应调节研究的进展,简要概述目前临床已经使用或最具应用潜力的辐射防护策略。     

Distribution and Fixation of Cesium and Strontium in Zeolite A and Chabazite

The selective removal and fixation of Cs and Sr have been studied in zeolite A and chabazite. Cesium ion was preferentially distributed into chabazite with a high distribution coefficient (K _Cs>10³ cm³·g^?1) in the presence of NaCl (10^?1 mol·dm^?3). The K _Sr values for zeolite A attained about 10³ cm³·g^?1 in the pH range of 8～10, and they gradually decreased with an decrease in pH.

The initial rate of Cs adsorption was fairly fast in chabazite, and the adsorption ratio reached almost 100% within a few hours. The adsorption ratio of Sr in binderless A zeolite reached almost 100% after 15 h. The adsorption of Cs and Sr on these zeolites was followed by Langmuir-type isotherm. Cesium forms of these zeolites recrystallized to pollucite (CsAlSi₂O₆) above 900°C for zeolite A and above 1,200°C for chabazite. As for Sr forms, these zeolites changed to SrAl₂Si₂O₆ above 900°C.

These recrystallized phases were suitable hosts for the immobilization of Cs and Sr in the nuclear waste solutions.     

清洁解控和退役若干动向与新发展

对国际辐射防护协会第 1 0届大会 ( IRPA-1 0 )涉及的清洁解控和退役问题作了论述 ,包括排除、豁免、清洁解控和废物最少化 ;退役工程技术的发展 ,包括去污技术、切割解体技术、探测技术 ;介绍了一个研究堆退役例子和加速器退役 ;最后 ,还论及了退役中受关注的一些问题 ,如 :石墨废物、混凝土废物、重水堆退役的氚防护、退役时间和退役废物量等。     

全国核与辐射安全监管信息系统的研究和建议

文章简要介绍了全国核与辐射安全监管信息系统的前期规划建设情况,包括基本建设内容、系统总体架构、以及工作中发现的影响和制约工作开展的主要问题,并提出了建议。     

Development and diversity and defense-in-depth application of ABWR feedwater pump and controller model

This work developed an advanced boiling water reactor (ABWR) feedwater pump and controller model, which was incorporated into Personal Computer Transient Analyzer (PCTran)-ABWR, a nuclear power plant simulation code. The feedwater pump model includes three turbine-driven feedwater pumps and one motor-driven feedwater pump. The feedwater controller includes a one-element/three-element water level controller and a specific feedwater speed controller for each feedwater pump. The performance tests, including step change of dome pressure, feedwater pumps transfer, inadvertent closure of all turbine control valves, and one feedwater pump trip at 100% power, demonstrate the feasibility of dynamic response of stand-alone model and incorporated model. Furthermore, a diversity and defense-in-depth analysis is performed to demonstrate the feasibility for motor-driven feedwater pump as an emergency core cooling system (ECCS) automatic diverse back-up. In Lungmen nuclear power plant (NPP), a diverse manual initiation means for the high pressure core flooder (HPCF) loop C is designed as the back-up of digitalized engineered safety features actuation system (ESFAS). If the motor-driven feedwater pump (MDFWP) can be an automatic digital diverse back-up for ESFAS, Lungmen NPP would be more robust to defend against software common-cause failure (CCF).     

Plastic and dissipated work and stored energy

This paper depicts one theoretical and experimental method to take into account the energy phenomena, associated with the elasto—plastic deformation process, during the elaboration of behaviour laws. The energy balance definition is examined in order to relate the stored energy of cold work to the hardening state variables. Two experimental approaches are used to study the evolution of the energy balance. The first one uses microcalorimetric technique and the second infrared technique. Several industrial metallic materials are studied by both approaches. Energy data are used to control the validity domain of the classical behaviour laws and to elaborate new more appropriate ones. Therefore, the hardening parameters cannot be identified with the thermodynamical forces. The use of energy considerations allows the definition of new thermodynamical forces and state variables, in the case of isotropic or kinematical hardening.     

Construction and operational experience with small and medium power reactors and expected improvements

Past experience with small and medium power reactors (SMPRs) in the areas of construction and operation is examined in this paper. Current development of SMPRs focuses on passive safety features; larger design and safety margins; reduction of construction periods through simplification, modularization and increased shop fabrication.