按提交时间
按主题分类
按作者
按机构
您选择的条件: 核科学技术其他学科
  • 基于APROS的核农耦合系统的仿真分析

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-06-06

    摘要: 为缓解气候变暖和实现3060双碳目标,国家优化产业和能源结构,推动煤炭清洁高效利用,大力发展新能源,在确保安全的前提下积极有序发展核电。相较于传统化石能源,核电更清洁、环保、低耗。然后,实际核电站热效率只有约33%,其余热量排放到环境中,造成严重浪费。其中,温排水排放到临近海域,热量对水体环境造成热影响。因此,高效利用温排水余热不仅可以提高核电站能源利用率,还能减少对水体环境的热污染,有助于节能减排。本文采用APROS软件对一套核电余热用于温室大棚和室内海水养殖的增温提产综合系统进行仿真分析,论证核农耦合系统的可行性,为我国核能余热综合利用提供科学依据。

  • Study of the response of 10B-doped MCP to wide-energy range neutrons from eV to MeV

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-31

    摘要: Neutron-sensitive microchannel plates (nMCPs) have applications in neutron detection, including energy spectrum measurements, neutron-induced cross-sections, and neutron imaging. 10B-doped MCPs (B-MCPs) have attracted significant attention owing to their potential for exhibiting a high neutron detection efficiency over a large neutron energy range. Good spatial and temporal resolutions are useful for neutron energy-resolved imaging. However, their practical applications still face many technical challenges. In this study, a B-MCP with 10 mol% 10B was tested for its response to wide-energy neutrons from eV to MeV at the Back-n white neutron source at the China Spallation Neutron Source. The neutron detection efficiency was calibrated at 1 eV, which is approximately 300 times that of an ordinary MCP and indicates the success of 10B doping. The factors that caused the reduction in the detection efficiency were simulated and discussed. The neutron energy spectrum obtained using B-MCP was compared with that obtained by other measurement methods, and showed very good consistency for neutron energies below tens of keV. The response is more complicated at higher neutron energy, at which point the elastic and non-elastic reactions of all nuclides of B-MCP gradually become dominant. This is beneficial for the detection of neutrons, as it compensates for the detection efficiency of B-MCP for high-energy neutrons.

  • 脉冲波形甄别中的最佳特征子集选择与降维研究

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-31

    摘要: 随着机器学习在中子-伽马(n-γ)甄别中的广泛应用,脉冲波形甄别中的特征子集选择成为一个值得关注的问题。经验方法、Random Forest分类和Logistic回归特征选择算法较为全面地完善了特征子集选择方法,核主成分分析(KPCA)则将特征子集进一步降维。实验结果表明,特征选择算法在微弱的核信号中表现不佳,错误率均达30%以上。经验方法中的特征子集选取范围则至关重要,特征子集“1-62”的错误率达到49.096%,远高于来自脉冲尾部的特征子集约1%的错误率。最优特征子集与尾积分对应的采样点不完全重合,但差异不大,尾积分对应的采样点可近似为最优特征子集。通过研究目前具有代表性的Random Forest分类、Logistic回归等特征选择算法和细致的经验方法,论文结果具有普适性,为特征子集的选择提供了进一步的理论支持。

  • Fe-Cr合金界面氦掺杂的第一性原理研究

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-22

    摘要: 作为聚变反应堆候选材料,低活化铁素体钢(马氏体钢)的主要成分是Fe和Cr。在实际工况下,聚变反应产生的氦会进入材料中,产生微观缺陷,从而引起辐照损伤,影响材料的抗辐照能力(氦脆现象)及其它物理性能。本文通过第一性原理计算,模拟得出反应堆主体材料Fe-Cr合金的界面,在不同的替代位和间隙位掺杂He原子,对其结构优化后计算每种结构的形成能,得出He原子在Fe-Cr界面不同位置处的稳定性。与此同时,通过对体积的计算得出He在靠近界面的Fe八面体间隙位时会引起较大的晶格畸变,根据电子态密度分析,推断是He、Fe、Cr三种原子在特定位置相互杂化影响的结果,为下一步研究核级不锈钢微观缺陷及其物理化学性质提供理论依据。

  • Fe-Cr合金界面氦掺杂的第一性原理研究

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-16

    摘要: 作为聚变反应堆候选材料,低活化铁素体钢(马氏体钢)的主要成分是Fe和Cr。在实际工况下,聚变反应产生的氦会进入材料中,产生微观缺陷,从而引起辐照损伤,影响材料的抗辐照能力(氦脆现象)及其它物理性能。本文通过第一性原理计算,模拟得出反应堆主体材料Fe-Cr合金的界面,在不同的替代位和间隙位掺杂He原子,对其结构优化后计算每种结构的形成能,得出He原子在Fe-Cr界面不同位置处的稳定性。与此同时,通过对体积的计算得出He在靠近界面的Fe八面体间隙位时会引起较大的晶格畸变,根据电子态密度分析,推断是He、Fe、Cr三种原子在特定位置相互杂化影响的结果,为下一步研究核级不锈钢微观缺陷及其物理化学性质提供理论依据。

  • Efficient and selective removal of Pb(II) from landfill leachate using L-serine-modified polyethylene/polypropylene nonwoven fabric synthesized via radiation grafting technique

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-08

    摘要: In this study, to efficiently remove Pb(II) from aqueous environments, a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent (NWF-serine) was fabricated through the radiation grafting of glycidyl methacrylate and subsequent L-serine modification. The effect of the absorbed dose was investigated in the range of 5–50 kGy. NWF-serine was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Batch adsorption tests were conducted to investigate the influences of pH, adsorption time, temperature, initial concentration, and sorbent dosage on the Pb(II) adsorption performance of NWF-serine. The results indicated that Pb(II) adsorption onto NWF-serine was an endothermic process, following the pseudo-second-order kinetic model and Langmuir isotherm model. The saturated adsorption capacity was 198.1 mg/g. NWF-serine exhibited Pb(II) removal rates of 99.8% for aqueous solutions with initial concentrations of 100 mg/L and 82.1% for landfill leachate containing competitive metal ions such as Cd, Cu, Ni, Mn, and Zn. Furthermore, NWF-serine maintained 86% of its Pb(II) uptake after five use cycles. The coordination of the carboxyl and amino groups with Pb(II) was confirmed using X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis.

  • Fe-Cr合金界面氦掺杂的第一性原理研究

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-08

    摘要: Fe-Cr合金作为聚变反应堆候选材料中低活化铁素体钢(马氏体钢)的主体成分,在实际工况下,聚变反应产生的氦会进入材料中,产生微观缺陷,从而引起辐照损伤,影响材料的抗辐照能力及其他物理化学性能。本文通过第一性原理计算,模拟得出反应堆主体材料Fe-Cr合金的界面,并在不同的间隙位置和替代位置掺杂He原子,结构优化后计算形成能,得出He原子在不同位置的稳定性。与此同时,通过对体积的计算得出He在靠近界面的Fe八面体间隙位时会引起较大的晶格畸变,这是He、Fe、Cr三种原子在特定位置相互杂化影响的结果。

  • 基于碎片云运动模型的缓发γ射线电离大气蒙特卡罗模拟

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-07

    摘要: 高空核爆炸碎片云释放出的缓发γ射线在高空非均匀大气的输运过程中电离大气,使得电离层中电子数密度剧增,进而影响途径电离层的无线电通信链路。为了准确描述随时空演化的缓发γ射线源电离大气过程,首先建立高空核爆炸碎片运动演化的流体力学模型,然后根据碎片云运动参数建立缓发γ射线分层等效体源模型,最后采用蒙特卡罗方法模拟缓发γ射线在高空大气中输运并电离大气的过程。针对碎片云形状随时间不断演化特性,采用辐射源分层抽样的方法得到缓发γ射线的初始位置。针对大气密度随高度指数衰减的特性,采用质量厚度抽样方法简化计算模型。结果表明:碎片云形状对缓发γ射线电离大气范围和强度存在明显影响。兆吨级高空核爆炸缓发γ射线电离大气范围可达千公里以上。当爆高不变当量增加时,碎片云高度和水平半径增大,缓发γ射线电离大气范围和强度有所增大。当当量不变爆高增加时,碎片云高度和水平半径增大,缓发γ射线电离大气范围增大,但强度有所降低。

  • 半导体智能剥离技术研究进展

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-07

    摘要: 智能剥离技术(Smart-Cut)是一种利用离子注入和晶片键合来转移超薄单晶层的技术。在先进微电子系统中,智能剥离技术作为半导体材料异质异构集成的重要技术手段之一,受到了学界和行业的广泛关注。智能剥离技术是在半导体材料表面单一注入或共注入氢、氦离子,并调控注入工艺参数(能量、温度、注量、注量率、注入顺序等),将半导体材料和衬底材料在低温下键合后,再进行退火(温度、时间、速率),使注入层内产生平行表面的微裂纹,从而实现层转移。本论文总结了近二十年第一、二、三、四代半导体智能剥离技术研究进展,分析了微观缺陷和微裂纹生长机制,探究了不同材料的剥离阈值差异原因,为理解和掌握智能剥离技术提供了参考,对利用智能剥离技术制备半导体器件有重要意义。

  • 抗干扰设计在高温堆吸收球停堆驱动机构机柜项目中的研究与应用

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-06

    摘要: 步进电机驱动器是高温汽冷堆核电站吸收球停堆驱动机构机柜的主要设备,采用PWM脉冲宽度调制技术,脉宽调制过程产生的高次谐波分量又反向影响驱动器的工作稳定性和精度,严重时可能引发吸收球误落而影响核电站正常运行,或引发吸收球拒落而影响核安全。通过深入研究PWM脉宽调制产生的干扰的作用机理、传输路径和影响程度,量身定制合适的电抗器和滤波器布置于干扰源传输路径上,可有效阻断干扰传播,抑制干扰的影响程度,同时通过优化机柜布线,采用合适的信号通讯电缆及可靠接地等综合手段,可有效解决驱动器PWM脉宽调制机制对长距离传输的弱电信号的影响,使步进电机稳定运行,提升系统运行可靠性和安全性。

  • CFETR核聚变发电厂储热技术对比

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-02

    摘要: 摘要:[目的] 为解决核聚变发电热功率输出不稳定性和汽轮发电机组平稳运行之间的矛盾,CFETR核聚变发电厂可运用储热技术可对核聚变堆的功率输出进行削峰平谷。储热技术有多种类型,各类储热技术对于核聚变发电厂的适用性亟需进行对比。[方法] 文章选取核聚变反应堆氦冷陶瓷增殖包层的参数作为储热技术边界条件,通过对储热技术适用温度范围进行评估,初步分析出有潜力运用于CFETR核聚变发电厂的三种储热技术,并对其进行成本进行初步预测。[结果]三大类储热技术均可选出适用CFETR核聚变发电厂氦冷增殖包层温度参数的储热介质。但化学储热由于其吸热和放热存在温差,造成能量的损耗的同时不利于系统的稳定性,显热储热技术和相变储热技术吸热温度和放热温度温差较小,具有应用于CFETR核聚变发电厂的潜力。初步经济性分析结果显示,相变储热成本最低,其次为熔融盐储热,再次为固相显热储热技术中利用硅砖作为储热介质,固相显热储热技术中利用铸钢作为储热介质成本最高。 [结论]储热技术中,熔融盐储热技术、相变储热技术、固相显热储热具有应用于CFETR核聚变发电厂氦冷增殖包层的先决条件。熔融盐储热技术成熟度较高,有大量工程应用,造价在相变储热和固相显热储热之间,运用潜力较大。相变储热的成本最低,参数同样适用于核聚变发电,但其技术成熟度较低,有望成为未来研究的重点。

  • 核燃料棒焊缝探伤在线自动化评价系统的设计与实现

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-01

    摘要: 本文针对核燃料棒焊缝质量检测的高效率和高精度需求,设计并实现了一套在线自动化评价系统。该系统采用B/S架构,结合先进的AI技术,实现了燃料棒焊缝的实时图像采集、管理和智能分析。系统前端使用Electron.js、React和Ant Design框架,后端基于Spring Cloud和Docker技术,确保了操作的便捷性和系统的稳定性。通过集成的AI模型,系统能够有效识别焊缝缺陷,提高了检测的准确性和生产效率。系统的成功实施,为核电站的安全运行和核能行业的质量控制提供了有力支持,并为未来自动化检测技术的发展奠定了基础。

  • 随钻D-T源中子孔隙度测井响应分析

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-04-29

    摘要: 随钻中子孔隙度测量通过测量热中子计数,评价地层减速长度从而获得地层孔隙度,是一种地层储集性评价的重要方法,被广泛应用在复杂油气田的勘探开发中。随钻D-T源中子孔隙度测井仪器由脉冲中子源和多探测器组成,随钻可控源中子孔隙度响应规律受仪器钻铤结构及仪器测量方式的影响,同时井眼参数、流体类型和地层等因素影响仪器周围的中子场分布及测井响应规律。本文利用蒙特卡罗模拟方法,研究不同钻铤结构及仪器设计、仪器测量环境因素和地层参数对随钻D-T源中子孔隙度测量过程中子通量分布与孔隙度响应规律的影响。仪器钻铤结构与测量环境影响分析结果表明,仪器采用侧开槽设计时探测器计数变大,但地层孔隙灵敏度仅为导流通道环绕设计的0.36倍,并明确钻铤尺寸是测量环境影响的主控因素。地层岩性、泥质含量和地层水矿化度的地层环境因素影响分析结果显示,岩性作为地层属性在不同孔隙度下的影响几乎为常量,泥质含量的影响程度在低孔条件下是地层水矿化度影响程度的2.9倍,高孔隙度下为1.48倍,因此地层泥质含量为地层环境影响的主控因素。

  • 基于SSA-XGBoost模型的高精度密度预测方法研究

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-04-25

    摘要: 复杂岩性井段对密度测井数据精度要求很高,传统的计算模型不能很好的满足此时的高精度要求。为此提出利用机器学习回归预测模型提高密度测井曲线的精度,考虑到XGBoost模型的过拟合问题,基于SSA算法改进XGBoost进而提出了SSA-XGBoost密度预测模型。采用蒙特卡罗模拟双探测器密度测井仪器,获取不同密度地层数据以验证该模型的预测效果。利用SSA算法优化SVR、RFR和LSTM参数,构建SSA-SVR、SSA-RFR和SSA-LSTM模型预测模拟地层密度,并使用量化评价指标和泰勒图模型对比分析各个模型的预测性能。此外,还分析了不同预测模型对实际密度测井数据的预测效果。结果表明SSA-XGBoost模型的预测精度高于传统脊-肋图模型,在实际密度测井数据处理中具有广阔的应用前景。

  • Grain boundary engineering for enhancing intergranular damage resistance of ferritic/martensitic steel P92

    分类: 核科学技术 >> 核科学技术其他学科 分类: 物理学 >> 核物理学 提交时间: 2024-02-28

    摘要: Ferritic/martensitic (F/M) steels have been widely used as structural material for thermal and nuclear power plants. However, it is susceptible to intergranular damage in service conditions, which is expected to be critical issues. In order to improve the intergranular damage resistance of F/M steel, thermomechanical process (TMP) was employed to achieve a grain boundary engineering (GBE) microstructure in a kind of F/M steel P92 in this study. TMP, including cold rolling to 6%, 9%, and 12% thickness reduction, respectively, followed by austenization at 1323 K for 40 min plus tempering at 1053 K for 45 min, were applied on as-received (AR) P92 steel. Both prior austenite grain (PAG) size, prior austenite grain boundary character distribution (GBCD), and the connectivity of prior austenite grain boundaries (PAGBs) were investigated. Compared with AR specimen, the PAG size does not change significantly. The fraction of coincident site lattice boundaries (CSLBs, 3 ≤ Σ ≤ 29) and Σ3n boundaries along PAGBs decreases with increasing reduction ratio due to the recrystallization fraction increases with increasing reduction ratio. The PAGBs connectivity of the 6%-deformed specimen deteriorates compared with that of AR specimen slightly. Moreover, the potentiodynamic polarization studies revealed that the intergranular damage resistance of studied steel could be improved by enhancing the fraction of CSLBs along PAGBs, indicating that TMP, involving low deformation, could enhance the intergranular damage resistance.

  • 简化FMM算法在束流剖面测量中的应用

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2023-11-09

    摘要: 加速器中利用荧光靶系统测量束流横向剖面,为进一步提高系统测量的准确度,本文提出了一种利用简化快速行进算法(Fast Matching Method,FMM)填充荧光靶标定线的方法,使填充后的荧光靶图像更真实地反映束流剖面信息。论文首先利用Matlab生成模拟荧光靶图像,对比分析了算法处理前后的模拟图像束流剖面参数,仿真结果表明经过处理后的模拟图像,其结构相似性(Structural Similarity Index measure,SSIM)更接近1、均方误差(Mean Square Error,MSE)更小。最后,利用医用重离子加速器HIMM(Heavy Ion Medical Machine)现场采集的荧光靶图像进行验证。结果表明,HIMM现场采集的图像经处理后,剖面测量结果接近评估值。本研究结果为后续束流横向剖面参数算法的FPGA算法加速提供了依据。

  • Optimization method of Hadamard coding plate in γ-ray computational ghost imaging

    分类: 核科学技术 >> 辐射物理与技术 分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 分类: 光学 >> 计算中的光学 分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2023-06-08

    摘要: Owing to the constraints on the fabrication of -ray coding plates with many pixels, few studies have been carried out on -ray computational ghost imaging. Thus, the development of coding plates with fewer pixels is essential to achieve -ray computational ghost imaging. Based on the regional similarity between Hadamard subcoding plates, this study presents an optimization method to reduce the number of pixels of Hadamard coding plates. First, a moving distance matrix was obtained to describe the regional similarity quantitatively. Second, based on the matrix, we used two ant colony optimization arrangement algorithms to maximize the reuse of pixels in the regional similarity area and obtain new compressed coding plates. With full sampling, these two algorithms improved the pixel utilization of the coding plate, and the compression ratio values were 54.2% and 58.9%, respectively. In addition, three undersampled sequences (the Harr, Russian dolls, and cake-cutting sequences) with different sampling rates were tested and discussed. With different sampling rates, our method reduced the number of pixels of all three sequences, especially for the Russian dolls and cake-cutting sequences. Therefore, our method can reduce the number of pixels, manufacturing cost, and difficulty of the coding plate, which is beneficial for the implementation and application of -ray computational ghost imaging.

  • Improved Cohen-Sutherland algorithm for TGS transmission imaging

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2023-05-31

    摘要: Laminar -scanning (TGS), an advanced -ray nondestructive analysis technique, is capable of locating and analyzing the nuclides in radioactive nuclear waste, and the scanning of TGS falls into two parts (e.g., transmission measurement and emission measurement). To be specific, transmission measurement lays the basis for the accurate measurement of non-uniform radionuclide content in TGS scanning. The scan data were obtained using the Monte Carlo tool Geant4 simulation, and a total of 25 voxels were divided into 5 in length and 5 in width in a square barrel. In this study, the encoding cropping algorithm based on the draped foot vector judgment was adopted to rapidly calculate the voxel trace matrix within the square bucket of nuclear waste, and the transmission images were reconstructed using the Ordered Subsets Expectation-Maximization(OSEM). The results indicated that the cropping speed of the improved coding algorithm was significantly increased compared with the original algorithm, and the relative mean deviation (RMD) and root mean square error(RMSE) between the reconstructed attenuation coefficient and the reference standard value tended to decrease with the increase of the cropped line segments in the voxel, and the Pearson correlation coefficient(PCC) tended to converge to be 1.0. The image quality evaluation parameters of high media density materials were better than those of low media density materials in the above three indexes. The reconstruction effect was relatively poor under the more complex filling material. When there were more than 10 cropped line segments in the voxel, the reconstruction data generally tended to be stable. The graphical trimming algorithm is capable of rapidly calculating the trace matrix of the scanned voxels, it shows the advantages of speed and efficiency, and it can serve as a novel method to solve the trace matrix of TGS nuclear waste transmission scans.

  • 运营单位: 中国科学院文献情报中心
  • 制作维护:中国科学院文献情报中心知识系统部
  • 邮箱: eprint@mail.las.ac.cn
  • 地址:北京中关村北四环西路33号
招募志愿者 许可声明 法律声明

京ICP备05002861号-25 | 京公网安备11010802041489号
版权所有© 2016 中国科学院文献情报中心