共查询到18条相似文献,搜索用时 125 毫秒
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<正>美国杜克大学的研究员能够化科幻为现实,设计出一种真实的隐形斗篷,能够让一个厘米级圆柱体在微波下隐形。研究小组发表在《自然材料学》杂志上的一份研究报告讲解了如何利用一个菱形斗篷隐形物体。然而,这项技术距离真实版哈利–波特隐形斗篷仍有一定的差距,只能实现一个方向的隐形效果,研究小组称很难在可见光下隐形。据悉,杜克大学电子工程师首个研制的功能性隐形斗篷是于2006年,尽管当时该设计非常新颖独特,但并未达到完美的隐形效果。目前,杜克大学实验室研究人员提出了最新设计方案,可以解决最初设计所存 相似文献
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《Antennas and Propagation, IEEE Transactions on》2009,57(5):1521-1527
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介绍了激光布里渊散射探测水下目标的原理,采用基于新型ICCD的布里渊散射激光雷达系统,进行了水下目标探测的相关实验。实验结果表明,激光布里渊散射探测水下目标在探测深度上具有很大优势,同时具有探测隐身目标的能力。 相似文献
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隐身是人类自古以来的美妙幻想和愿望。近年来,随着人工微结构超构材料领域的不断发展,隐身具备了坚实的科学理论基础和实现条件。早期的隐身设计大多数是基于变换光学原理,科学家们利用超构材料实现了渐变的折射率并在多个频段实现了隐身现象。然而,变换光学隐身器件通常具有较大的尺寸且不易制备,这极大地限制了隐身器件的应用和发展。近年来,超表面作为超构材料的二维对应物,由于其轻薄特性、制备容易、以及强大的电磁波调控能力吸引了人们广泛的关注和研究兴趣。利用超表面实现的超薄隐身器件有望解除传统隐身器件对大尺寸和极端参数材料的依赖,进一步推动了隐身领域的发展,并使隐身器件迈向实际应用。文中对近年来基于超表面的超薄隐身器件的相关研究进行了简要的回顾,着重介绍了其隐身原理,实现方法以及优劣势,最后对领域发展前景和方向提出了一些建议。 相似文献
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The authors develop an object-based rate control algorithm for MPEG-4 arbitrarily shaped video object coding. There are three main contributions. An improved quadratic rate-distortion model for texture information is derived, which is more accurate for arbitrarily shaped video objects. Secondly, an accurate rate-distortion model for shape information is introduced. Combining the rate-distortion models for texture and shape information, an object level rate control is proposed. To achieve constant bit rate, the quantiser is adjusted based on buffer fullness. The tradeoff between picture quality and buffer fullness is considered. Compared with the rate control algorithm for the MPEG-4 verification model, the proposed scheme can achieve a more stable buffer without sacrificing picture quality. 相似文献
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《Journal of Visual Communication and Image Representation》2000,11(2):130-141
In this paper, we propose an active contour algorithm for object detection in vector-valued images (such as RGB or multispectral). The model is an extension of the scalar Chan–Vese algorithm to the vector-valued case [1]. The model minimizes a Mumford–Shah functional over the length of the contour, plus the sum of the fitting error over each component of the vector-valued image. Like the Chan–Vese model, our vector-valued model can detect edges both with or without gradient. We show examples where our model detects vector-valued objects which are undetectable in any scalar representation. For instance, objects with different missing parts in different channels are completely detected (such as occlusion). Also, in color images, objects which are invisible in each channel or in intensity can be detected by our algorithm. Finally, the model is robust with respect to noise, requiring no a priori denoising step. 相似文献
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本文将流体力学领域的微分-Thompson变换与时域有限差分(FDTD)技术结合起来,所形成的Thompson-FDTD方法,首次用来计算和分析任意形状介质体的电磁散射特性。该方法至少具有两个明显的优点:可以把不规则形体变换成规则形体,有利于精确匹配边界条件;可以任意调配网格分布,有利于提高计算精度。其数值实现进一步证实了该方法能精确模拟任意形状介质目标的电磁散射过程。 相似文献