共查询到20条相似文献,搜索用时 78 毫秒
1.
研究了基于NaI便携式γ谱仪的核素识别算法,包括能谱光滑去噪、峰位识别、峰边界确定、基于特征峰的核素定性识别。将BP神经网络引入核素识别当中,分别采用全谱识别法和特征向量识别法对核素进行识别。全谱识别法以γ能谱每道计数作为神经网络的输入值,能充分利用能谱数据,提高结果的准确性。特征向量识别法是对能谱进行小波包分解得到频域的若干个特征值,作为神经网络的样本,大大降低了输入维数,提高了训练速度。 相似文献
2.
《核电子学与探测技术》2017,(10)
针对γ能谱分析中重峰及强噪声背景下弱峰存在时特征提取困难的问题,提出了基于稀疏表示的γ能谱特征提取方法。采用匹配追踪算法提取能谱特征,获取能谱稀疏分解系数,然后使用所获特征训练模糊决策树,最后利用测试样本在所训练决策树中的识别准确率来验证特征提取效果。实验结果表明:该方法避免了传统的预处理过程,能有效地对γ能谱进行特征提取。 相似文献
3.
4.
《核电子学与探测技术》2016,(8)
针对传统γ能谱识别方法对高本底、低分辨率的复杂γ谱解析效果不明显、准确率低等问题,提出了一种基于支持向量机的核素识别方法。通过能谱预处理方法,获取能谱特征信息,将核素库的建立与分类器的构造相结合,使用实际能谱进行验证。通过谱仪对3种核素的不同组合进行能谱实测,实验结果表明,通过支持向量机的分类方法,对实测混合核素的识别准确率达到94%以上。 相似文献
5.
6.
为满足便携测量γ能谱并识别核素的功能要求,设计了一种基于Windows CE的手持便携式γ能谱核素识别仪。为了达到快速、准确识别核素的目的,根据Windows CE系统的轻便、性能稳定及功能丰富的特点,采用了基于RISC微处理器(Advanced RISC Machine Cortex-A8,ARM)的S5PV210嵌入式核心板作为主控板,定制底板、外扩通讯接口等,使得仪器轻巧便携、操作方便以及低功耗。在整机平台测试中,对处理程序中运用萨维茨基第一类滤波器的谱线光滑,对称零面积法寻峰以及核素识别等效果进行了评估。实验结果表明:仪器能快速、准确识别基本核素。 相似文献
7.
探讨了一种基于模糊逻辑与概率因子迭加算法识别γ谱中低计数率核素的分析方法。对241Am、133Ba、137Cs、60Co、152Eu五种核素不同测试时长的多核素实测谱进行测试。结果表明,本算法随着迭加次数的增加,核素识别率迅速上升。概率因子迭加次数达到15次以上时,核素识别准确率增长趋势变缓,对不同测试样本的识别率均在98%以上。该算法比传统算法具有更高的识别率,尤其在对多核素混合的复杂核素谱识别方面表现出较强的优势。 相似文献
8.
9.
10.
研究了一种应用于γ散射本底扣除的改进型非线性迭代剥峰算法(Statistics-sensitive Nonlinear Iterative Peak-clipping,SNIP)方法,该方法拟合了峰宽与能量的关系,并通过该关系实时获取峰宽,实现了变换宽度自适应,改善了固定峰宽无法对全谱的散射本底进行准确扣除的缺陷。实验结果表明:本文提出的自适应变换峰宽SNIP算法结构简单,动态效果好,与传统和其他改进的SNIP算法相比,γ能谱的散射本底扣除效果得到了进一步改善,并可以达到优化核素识别的效果,为核素识别方法提供了更多的选择。 相似文献
11.
Hasan M. KHAN Ijaz A. BHATTI 《核技术(英文版)》2007,18(1):26-29
Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence (TL) is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture (NIFA), Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities (TL1) than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves (TL2). The ratio of the area of first glow curve to that of second glow curve (TL1/TL2) was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results (comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves), all the irradiated and unirradiated samples of wheat and rice were unequivocally identified. 相似文献
12.
为对自制的活性面积高达1 000 cm2的大面积源进行表面发射率定值,同时作为现有2πα、2πβ表面发射率标准装置能力的扩充,研制了一套内置式大面积2π多丝正比计数器测量系统,并利用活性区直径为8 mm的241Am点源及活性区面积为10 cm×15 cm的大面积241Am和90Sr-90Y源对其进行计量学性能测试。结果表明:计数器内计数响应均匀性优于±0.4%,有效探测面积达1 400 cm2;所得241Am源高压坪曲线的坪长为1 400 V,坪斜为0.27%/100 V,坪区内计数变化为0.87%;90Sr-90Y源高压坪曲线的坪长为300 V,坪斜为0.75%/100 V,坪区内计数变化为0.80%;10次测量重复性好于0.4%,8 h内短期稳定性好于0.3%,1 a内长期稳定性好于0.8%。 相似文献
13.
LIU Xiuhua XU Yunshu ZHONG Zhijing FU Yibei DENG Yi 《核技术(英文版)》2007,18(1):59-64
Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn (11). When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight. 相似文献
14.
FU Shen SUNYi LU Yaohong 《核技术(英文版)》2007,18(2):65-72
Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes. 相似文献
15.
This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet. 相似文献
16.
WEI Min LIAO Jiali LIU Ning ZHANG Dong KANG Houjun YANG Yuanyou YANG Yong JIN Jiannan 《核技术(英文版)》2007,18(5)
The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) >SHA (HA from the surface) >THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g)ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5 - 6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site. 相似文献
17.
为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现:从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。 相似文献
18.
《核技术(英文版)》2014,(5):F0003-F0003
<正>1.NUCLEAR SCIENCE AND TECHNIQUES(NST),a bimonthly journal,is devoted to all aspects of nuclear science and technology,theoretical or experimental.Its special interest lies in the subjects of synchrotron radiation science and technology;low energy accelerators,radiation technology and applications;radiochemistry,radiopharmaceuticals and nuclear medicine;nuclear electronics and instrumen- 相似文献
20.
LI Lin SHEN Liren ZHU Qing WAN Tianmin 《核技术(英文版)》2007,18(4):193-197
Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described. 相似文献