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基于模型的完全迭代算法(IMR)对肾脏小结石诊断价值的实验研究 被引量:6
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作者 田娟 沙琳 +1 位作者 赖声远 刘书峰 《临床放射学杂志》 CSCD 北大核心 2017年第9期1359-1363,共5页
目的通过实验对比研究,探讨基于模型的完全迭代算法(IMR)技术对肾脏小结石的诊断价值。方法制作肾结石体模:单个重量(300±30)g的猪肾4个,将每个肾脏自肾脏一极沿冠状面切开至肾盂水平,将大小分别为2 mm、1 mm、0.5 mm的尿酸结石各2... 目的通过实验对比研究,探讨基于模型的完全迭代算法(IMR)技术对肾脏小结石的诊断价值。方法制作肾结石体模:单个重量(300±30)g的猪肾4个,将每个肾脏自肾脏一极沿冠状面切开至肾盂水平,将大小分别为2 mm、1 mm、0.5 mm的尿酸结石各24枚(每个肾脏6枚)分别植入肾皮质、肾髓质及肾盂,将植入结石的肾脏放置于注满生理盐水圆柱形有机容器,对体模进行CT扫描,用滤波反投影法(FBP)、高级迭代重组算法(iDose^4)、IMR技术分别重组出层厚为0.8 mm、层间距为0.3 mm的图像,对不同尺寸结石诊断的敏感性、特异性、准确性、数量、诊断结石的信心及图像质量进行评估。结果主观评价指标:(1)IMR图像的质量评分相对于FBP及iDose^4图像,有统计学意义。(2)IMR图像的噪声低于FBP及iDose^4图像,且iDose^4图像的噪声低于FBP。(3)对于2 mm、1 mm的结石三种重组方法对结石的检出率(均为100%)及正确诊断的信心(均为3分)没有统计学意义。对于0.5 mm的结石IMR技术对结石的检出率及正确诊断的信心与FBP和iDose^4比较,P<0.05,有统计学意义。客观评价指标:FBP、iDose^4、IMR技术所得图像的噪声和信噪比分别为[(5.8±0.5)HU,9.1±0.6]、[(4.1±0.3)HU,13.5±0.5]、[(1.9±0.3)HU,28.2±0.5],三组图像的噪声和信噪比两两比较,差异均有统计学意义。结论相对于FBP与iDose^4图像,IMR技术能在提高图像质量的同时提高微小结石诊断的准确性。 展开更多
关键词 滤波反投影法 高级重组算法 基于模型的完全迭代算法 结石
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全模型迭代重建算法评价^(125)I粒子植入术后CT图像 被引量:4
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作者 韩佳悦 孙连鑫 +2 位作者 沙琳 张晓虹 赖声远 《中国医学影像技术》 CSCD 北大核心 2018年第7期1090-1093,共4页
目的探讨全模型迭代重建(IMR)算法评价^(125)I粒子植入术后图像的应用价值。方法收集接受^(125)I粒子植入术及术后CT随访的16例腹部肿瘤患者,对扫描原始数据分别以滤波反投影法(FBP)、IMR和高级重建迭代(iDose^4)算法进行重建,比较3种... 目的探讨全模型迭代重建(IMR)算法评价^(125)I粒子植入术后图像的应用价值。方法收集接受^(125)I粒子植入术及术后CT随访的16例腹部肿瘤患者,对扫描原始数据分别以滤波反投影法(FBP)、IMR和高级重建迭代(iDose^4)算法进行重建,比较3种重建方法图像的噪声、伪影指数(AI)、CNR和主观评分。结果 FBP重建图像的噪声、CNR及AI分别为(58.65±4.03)HU、1.09±0.43和51.60±9.23,iDose^4图像分别为(48.38±5.34)HU、1.29±0.48和43.77±4.91,IMR图像分别为(41.46±3.44)HU、1.58±0.56和38.51±4.64,3种重建方法图像的噪声、CNR及AI两两比较差异均有统计学意义(P均<0.05)。IMR图像的主观图像质量评分显著高于FBP和iDose^4算法图像(调整后P<0.001,P=0.011)。结论 IMR算法获得的图像质量较高,可有效减少^(125)I粒子伪影,为^(125)I粒子植入术后随访与疗效评估提供了更佳方法。 展开更多
关键词 体层摄影术 X线计算机 基于模型的完全迭代算法 125I粒子 金属伪影
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函数族Julia集的Hausdorff维数
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作者 杨存基 《北京师范大学学报(自然科学版)》 CAS CSCD 北大核心 2009年第2期130-133,共4页
Stallard曾经用一族特殊的整函数说明了超越整函数的Julia集的Hausdorff维数可以无限接近1.本文证明了该函数族的完全迭代的Julia集的Hausdorff维数也可无限接近于1.
关键词 函数族 完全迭代 JULIA集 HAUSDORFF维数
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Iterative Learning Control With Incomplete Information: A Survey 被引量:12
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作者 Dong Shen Senior Member IEEE 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2018年第5期885-901,共17页
Abstract--This paper conducts a survey on iterative learn- ing control (ILC) with incomplete information and associated control system design, which is a frontier of the ILC field. The incomplete information, includ... Abstract--This paper conducts a survey on iterative learn- ing control (ILC) with incomplete information and associated control system design, which is a frontier of the ILC field. The incomplete information, including passive and active types, can cause data loss or fragment due to various factors. Passive incomplete information refers to incomplete data and information caused by practical system limitations during data collection, storage, transmission, and processing, such as data dropouts, delays, disordering, and limited transmission bandwidth. Active incomplete information refers to incomplete data and information caused by man-made reduction of data quantity and quality on the premise that the given objective is satisfied, such as sampling and quantization. This survey emphasizes two aspects: the first one is how to guarantee good learning performance and tracking performance with passive incomplete data, and the second is how to balance the control performance index and data demand by active means. The promising research directions along this topic are also addressed, where data robustness is highly emphasized. This survey is expected to improve understanding of the restrictive relationship and trade-off between incomplete data and tracking performance, quantitatively, and promote further developments of ILC theory. Index Terms--Data dropout, data robustness, incomplete in- formation, iterative learning controi(ILC), quantized control, sampled control, varying lengths. 展开更多
关键词 Data dropout data robustness incomplete information iterative learning control(ILC) quantized control sampled control varying lengths
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Iterative Multireference Configuration Interaction
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作者 Wen-yan Zhang Fei-wu Chen 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2019年第6期701-707,I0002,I0003,共9页
Iterative multireference configuration interaction (IMRCI) is proposed. It is exploited to compute the electronic energies of H2O and CH2(singlet and triplet states) at equilibrium and non-equilibrium geometries. The ... Iterative multireference configuration interaction (IMRCI) is proposed. It is exploited to compute the electronic energies of H2O and CH2(singlet and triplet states) at equilibrium and non-equilibrium geometries. The potential energy curves of H2O, CH2(singlet and triplet states) and N2 have also been calculated with IMRCI as well as the M?ller Plesset perturbation theory (MP2, MP3, and MP4), the coupled cluster method with single and double substitutions (CCSD), and CCSD with perturbative triples correction (CCSD(T)).These calculations demonstrate that IMRCI results are independent of the initial guess of configuration functions in the reference space and converge quickly to the results of the full configuration interaction. The IMRCI errors relative to the full configuration interaction results are at the order of magnitude of 10-5 hartree within just 2-4 iterations. Further,IMRCI provides an efficient way to find on the potential energy surface the leading electron configurations which, as correct reference states, will be very helpful for the single-reference and multireference theoretical models to obtain accurate results. 展开更多
关键词 Multireference configuration interaction Configuration interaction Full configuration interaction Iterative multireference configuration interaction
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自适应多重网格有限元的算法设计 被引量:1
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作者 胡显承 刘金亭 《清华大学学报(自然科学版)》 EI CAS CSCD 北大核心 1989年第6期86-95,共10页
给出了 MG网格列的定义和生成,在此基础上具体讨论了自适应性完全多重网格有限元方法的算法设计,收敛性和工作量估计。最后是例题试算和结果分析。
关键词 自适应多重网格 有限元 算法设计 MG网格列 完全多重网格
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