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1.
In this paper, the multiple refraction phenomenon is investigated on the boundary of a scalar impedance surface (SIS) and a tensor impedance surface (TIS). When a surface wave (SW) propagates on the SIS and radiates to the boundary of the TIS, the propagation direction of it is changed and the refraction phenomenon is accrued. The method that is proposed in this paper can predict the multiple refraction for the SW. Moreover, another analytical method is introduced for designing the proposed structure which the double refraction (DR) occurs at arbitrary angles on it. Using it, a sample of the structure is designed by printed circuits in 15.2GHz and the results are verified by the full‐wave simulation and measurement. The results are shown that in the structure, DR is occurred in 2° and 22° as predicted. The proposed method can provide many applications such as design of SW power dividers based on the TISs, impedance surface based waveguides, holographic antennas, and feeding of array antennas. 相似文献
2.
Koji Kamagata Christina Andica Ayumi Kato Yuya Saito Wataru Uchida Taku Hatano Matthew Lukies Takashi Ogawa Haruka Takeshige-Amano Toshiaki Akashi Akifumi Hagiwara Shohei Fujita Shigeki Aoki 《International journal of molecular sciences》2021,22(10)
There has been an increasing prevalence of neurodegenerative diseases with the rapid increase in aging societies worldwide. Biomarkers that can be used to detect pathological changes before the development of severe neuronal loss and consequently facilitate early intervention with disease-modifying therapeutic modalities are therefore urgently needed. Diffusion magnetic resonance imaging (MRI) is a promising tool that can be used to infer microstructural characteristics of the brain, such as microstructural integrity and complexity, as well as axonal density, order, and myelination, through the utilization of water molecules that are diffused within the tissue, with displacement at the micron scale. Diffusion tensor imaging is the most commonly used diffusion MRI technique to assess the pathophysiology of neurodegenerative diseases. However, diffusion tensor imaging has several limitations, and new technologies, including neurite orientation dispersion and density imaging, diffusion kurtosis imaging, and free-water imaging, have been recently developed as approaches to overcome these constraints. This review provides an overview of these technologies and their potential as biomarkers for the early diagnosis and disease progression of major neurodegenerative diseases. 相似文献
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Shape from focus (SFF) is a widely used passive optical method for 3D shape reconstruction. In SFF, a focus measure, which is used to estimate the relative focus level, plays a critical role in depth estimation. In this article, we present a new focus measure for accurate 3D shape estimation in optical microscopy based on the analysis of 3D structure tensor. First, the 3D tensors are computed from the input image sequence for each pixel. Then, each tensor is decomposed into point, curve, and surface tensors by decomposing tensors into eigenvalues and eigenvectors. Finally, the surfaceness is used to measure the quality of sharpness. The proposed focus measure provides accurate focus values and better resistance against noise. The proposed measure is evaluated by conducting experiments using image sequences of simulated and microscopic real objects. The comparative analysis demonstrates the effectiveness of the proposed focus measure in recovering 3D shape. 相似文献
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基于钢丝绳的结构特点及受载情况,设计制作了一种新型钢丝绳夹具。该夹具夹紧过程既方便快捷又安全高效,尤其适用于大张力钢丝绳施工、测试及锚定前的夹紧过程中。 相似文献
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在理论上,利用O‘Connell的饱和水裂隙岩体等效弹性模量与岩石模量的关系式,并由式中的裂隙密度概念意义,建立了温度作用下的裂隙密度与Oda提出的裂隙张量之间的关系式;在试验的基础上,给出了温度、饱和水下的单裂隙岩体应力-应变、抗压强度回归拟合关系表达式。并通过试验与拟合结果对以加以验证,其裂隙岩体力学模型可为裂隙岩体THM耦合分析提供合理的依据。 相似文献
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中国西部钻孔应变仪台网工作回顾与前瞻 总被引:4,自引:0,他引:4
中国西部钻孔应变仪观测台网始建于上世纪80年代末期,采用的RZB-1型电容式钻孔应变仪具有10^-10量级的应变灵敏度和小于10^-7/a的飘移。9台仪器分别安装在新疆、甘肃与四川的乌什、西昌和武都等台站,以观测因构造活动引起的地壳应变能的积累,并研究相关的地震前兆特征。总结了台网建设与观测工作,及其用于对台站附近发生的强震的监测预报结果。其中,4种类型的震前异常应变变化较为明显:(1)应变固体潮畸变与年周变畸变;(2)幅度达10^-6应变的积累.并伴随压、张性跳变;(3)异常应变积累持续时间达数月;(4)测得的主应力方向震前向震中方向偏转。最后,对发展我国井下观测技术提出了3点建议。 相似文献