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由于电容层析成像(ECT)图像重建的经典算法Landweber迭代法具有半收敛性,从而限制了其在多相流检测中的广泛应用。为了解决这一问题,从数学角度对Landweber法的半收敛性进行分析证明,并找到其物理本质原因。通过构造压缩算子提出一种全收敛的Landweber法,使得该方法具有稳定的收敛特性。同时,对ECT敏感场的“软场”特性进行分析,针对忽略“软场”特性所导致的经典Landweber法对不...
Recent studies have identified neural correlates of language effects on perception in static domains of experience such as colour and objects. The generalization of such effects to dynamic doma...
We examine the role of declining mortality in explaining the rise of retirement over the course of the 20th century. We construct a model in which individuals make labor/leisure choices over their li...
In this paper we studied and examined the formulation of conservation laws on dynamic moving deforming meshes, in the context of the Geometric Conservation Law (GCL) compliant high order temporal and ...
The theory of non-oscillatory scalar schemes is developed in this paper in terms of the local extremum diminishing (LED) principle that maxima should not increase and minima should not decrease. This ...
Mirror mimicry has well-known consequences for the person being mimicked: it increases how positively they feel about the mimicker (the Chameleon Effect). Here we show that anatomical mimicry h...
Pansy, Viola × wittrockiana, is a popular ornamental plant. Eff ects of polyploidy on phenotype and four pollination methods on capsule and seed set were studied using ten octoploid (2n = 8x) ...
Eff ect of the end-of-day and the end-of-night red and blue light in dill growth was investigated. Ambrozja dill (Anethum graveolens L.) cvs were grown in vegetation chambers in completely con...
Carbon dioxide is one of the most important greenhouse gases. Agriculture, especially soil tillage, contributes to CO2 emissions signifi cantly. h e aim of the paper was the comparison of the a...
针对传统电容层析成像(ECT)流型辨识方法识别率较低的问题,提出一种基于压缩感知理论的ECT流型辨识方法。首先,将ECT系统获得的测量电容向量归一化,并表示为训练样本集的过完备字典稀疏线性组合;然后,将随机高斯矩阵作为测量矩阵对测试样本和标准样本分别进行采样,并利用压缩感知信号重构算法求解L0范数下的最优化问题,从而得到各样本在训练样本集上的稀疏表示;根据待测样本和标准样本稀疏解之间的线性相关程度...
Hardfacing metals are widely used in arc welding and plasma transfer arc technologies and industries. However, application of hardfacing in agriculture is limited due to low toughness after weld depos...
针对电容层析成像技术(ECT)的图像重建质量精度较低的问题,提出了一种基于粒子滤波的ECT图像重建方法。首先,分析了ECT图像重建基本原理,以系统状态估计的方式描述了ECT图像重建最优解的搜索过程,并建立了状态空间模型。然后,以线性反投影(LBP)算法的图像重建结果作为初始状态,利用测量信息对从状态空间中获取的随机样本进行最优加权,以获得重建图像的最小方差估计。最后,对5种不同的流型进行了仿真实验...
评价CEUS和ECT在甲状腺低回声结节良恶性中的鉴别诊断价值。方法 对186个确诊的良恶性甲状腺低回声结节行ECT和CEUS,对比两种方法的诊断敏感度、特异度、阳性预测值、阴性预测值及符合率,同时绘制ROC曲线,并比较曲线下面积。结果 186个甲状腺低回声结节,病理诊断良性结节117个,恶性结节69个,良性结节在注射造影剂后以高增强和等增强为主,恶性结节以低增强为主。CEUS诊断甲状腺低回声结节的...
Tractor performance tests conducted under laboratory test conditions are important because these tests determine the performance characteristics used to compare strengths and weaknesses of tractors. ...
针对电容层析成像系统中的 “软场 ”效应和病态问题 ,将最小二乘法和迭代法相结合 ,提出了一种最小二乘约束迭代的图像重建算法。给出了算法的数学模型 ,完成了算法的收敛性分析和证明 ,算法在图像重建中使迭代步长在保证收敛的情况下达到最优。仿真和实验结果表明 ,该方法与最小二乘法相比 ,具有更稳定、成像效果好等特点 ,为 ECT图像重建提供了一种新的有效方法。

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