共查询到18条相似文献,搜索用时 52 毫秒
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为了进一步提高特征线方向概率方法(CDP)的计算效率,提出了一种角度相关的边界均匀化方法。提出CDP性能分析模型,显性地比较分析特征线方法(MOC)和CDP的计算效率。数值结果表明,所提模型正确,并显示出CDP在计算效率方面的优势。 相似文献
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在论述X射线线阵列探测器辐射数字成像系统的基础上,对X射线线阵列探测器辐射数字成像系统获取的图像的非均匀性产生机理进行了理论分析,并在理论分析基础上从测量和校正的角度对各种非均匀性产生因素进行了分类,以便对图像的非均匀性校正的方法及减小图像非均匀性产生的技术途径。 相似文献
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X射线线阵列探测器均匀性研究 总被引:1,自引:0,他引:1
陈敏聪 《核电子学与探测技术》2011,31(2):200-203
实验测试了芬兰X-SCAN0.4f线阵列探测器在X射线扫描前后的成像均匀性.得出扫描前阵列探测器各单元的本底输出随时间的漂移规律和扫描后各单元对X射线的响应规律.结果发现阵列探测器各单元扫描前后的响应均存在不一致性.通过偏置和增益的校准虽然可以达到各单元响应的一致性,但没有真正解决各单元响应不一致的问题,这对定量计算会... 相似文献
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离散纵标法是求解中子输运方程的主要数值方法之一,空间变量离散及误差控制对保证输运计算精度至关重要。传统有限差分离散方法对于特定模型会产生非物理振荡问题,粗网精度不足使得低阶差分方法的应用具有局限性。本文研究了二维常数和线性短特征线方法,短特征线空间离散基于中子输运的特征线解,根据输运方程的空间矩守恒构造网格角通量密度完成输运方程求解。选取固定源和临界问题进行测试验证并分析了网格敏感性。数值结果表明,线性短特征线离散对网格敏感性较低,较常数短特征线和低阶差分方法具有更高的计算精度及效率。 相似文献
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以栅元为模块进行特征线跟踪的中子输运方程解法 总被引:3,自引:1,他引:2
为解决复杂几何条件下中子输运方程的求解问题,分析了特征线法理论模型,探讨了以栅元为模块的高效特征线产生方法,以及与之相关的空间角度离散和边界条件处理问题.采用自行研制的特征线法数值计算软件--PEACH,对经济合作组织核能机构(OECD/NEA)UO2和MOX燃料混合装载的7群(C5G7MOX)基准问题的数值进行了检验.结果表明,无论是计算Keff还是棒功率分布该方法都具有很高的精度. 相似文献
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A three-dimensional ray tracing study of a whistler-mode chorus is conducted for different geomagnetic activities by using a global core plasma density model. F... 相似文献
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Ray tracing study of electromagnetic ion cyclotron (EMIC) waves is conducted based on a realistic plasma density model. The simulation result shows that EMIC waves propagate away from the equatorial source region to higher latitudes basically along geomagnetic field lines, and are reflected at the region where their frequency matches the local bi-ion frequency. H+ band suffers H+-He+ bi-ion frequency reflection at lower latitudes, whereas He+ band suffers He+-O+ bi-ion frequency reflection at higher latitudes. Moreover, the concentration of heavy ions slightly affects the bi-ion frequencies and then slightly determines the reflection location of ray paths of EMIC waves. The current results present the first detailed study on the propagation characteristics of EMIC waves associated with bi-ion frequencies. 相似文献
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吴学周 《核电子学与探测技术》1991,11(1):46-51
效率示踪法是由Campion提出并发展的。本文描述了效率示踪法的原理、局限性;效率示踪法在液体闪烁计数器中的应用。Packard液体闪烁计数器中ET测量结果也作了介绍。 相似文献
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In the current situation of the increasingly serious terrorist activities, explosives were hidden inside the package by terrorists. The main task for international anti-terrorism is to detect the explosives hidden in the package timely and precisely. The chemical elemental composition of explosive is mainly C, H, O and N. Daily necessities are also composed of these four elements. There is a great difference for elemental ratio between daily necessities and the explosive. The atomic density and relative content of C, H, O and N can be determined, which can distinguish explosive from organics. A removable explosive detection device based on tagged neutron method was developed. The tagged neutron method (TNM) technique is mainly based on the principle of coincidence to reduce the background of spectrum. The contents of chemical elements (C, N, O) and the ratio of C/O and C/N in the explosive were determined by analyzing the characteristic gamma energy spectrum to determine the existence of explosives. The ING-27 neutron generator and Φ76×76 mm LYSO scintillator detectors are selected in the experiment. Explosives detection devices are used to measure the sample of explosives surrogate, organic and explosives placed behind organic in the package. The results show that this method can effectively distinguish between explosive TNT and organic dry milk powder. 相似文献