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Design of infrared camouflage cloak for underground silos

Defence Technology（防务技术） 2020年第1期16卷 43-49页

作者： Luo Zhang Qiang Zhang Hong Ye Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei 230027PR China

The temperature difference between the exposed surface of an underground silo and the surrounding soil surface is significant,which means a silo can be easily found by infrared *** designed an infrared camouflage cloak consisting of an imitative layer and an insulation layer for the *** imitative layer is used to imitate the thermal response of the soil to the surrounding *** insulation layer is used to weaken the impact of the internal temperature field of the silo on the lower boundary of the imitative layer.A silo model including surrounding soil and a soil model without silo were established,and the influences of the material and thickness of each layer on the infrared camouflage effect were *** results show that when using a silicone rubber containing alumina powder with a volume fraction of 3.18% as the imitative material,its thermal inertia is in consistent with that of the ***,it was found that the thickness of the imitative layer doesn't need to be greater than its thermal penetration depth to achieve the infrared camouflage,and the absence of the insulation layer will cause hot spots on the silo surface in winter to weaken the camouflage *** optimized thicknesses of the imitative layer and the insulation layer are 22 cm and 4 cm re *** simulations indicate that with the application of the cloak,the maximum value of the absolute values of the temperature differences between the average temperatures of the silo surface and the surrounding soil surface temperatures drops from 1,59℃ to 0.31℃ in summer and from 1.92℃ to 0.21℃ in *** designed cloak can achieve an all-weather and full-time passive infrared camouflage.

关键词： Underground silo Infrared camouflage cloak Imitative layer Insulation layer

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Layered and isotropic acoustic cloak design based on conformal transformation acoustics

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Science China(Physics,Mechanics & Astronomy) 2011年第4期54卷 593-597页

作者： REN ChunYu XIANG ZhiHai CEN ZhangZhi Key Laboratory of Applied Mechanics Tsinghua University Chinese Ministry of Education Beijing 100084 China Department of Naval Architecture and Ocean Engineering Naval University of Engineering Wuhan 430033 China

The acoustic cloak can manipulate sound waves in surprising ways and enable us to guide the trajectories of waves at *** contrast to the existing approaches for designing such devices that need exotic material parameters,here we demonstrate how to design a layered and isotropic acoustic cloak based on conformal transformation acoustics.A petal-shaped layered acoustic cloak is designed from the reduction of material parameters of an approximate rectangular *** resultant material parameters span a narrow range,thus strongly facilitating the *** invisibility performance of the cloak for different shapes of acoustic wavefront is verified using a full-wave finite-element analysis.

关键词： Conformal transformation acoustics cloak isotropic material layered

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In-band metamaterial cloak based on the interplay of absorption and transmission

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光电工程 2017年第1期44卷 92-96页

作者： Zeyu Zhao Hongbo Sun State Key Laboratory on Integrated Optoelectronics College of Electronic Science and Engineering Jilin University

A microwave metamaterial shelter with an electromagnetic narrow window over a broad absorption spectrum is experimentally demonstrated by resorting to conventional impedance-matching theory and metamaterial *** device consists of a broad absorber and an embedded electric resonator,and has the ability of permitting one to"see"surroundings but not to be readily sensed by outside *** origin is verified to be a dipole oscillation excited in absorbing region which can induce selective re-emission of the captured energy towards the enclosed *** performance of"observing without being perceived"is numerically presented.

关键词： metamaterial cloak absorption

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Improvement of Cylindrical cloak by Layered Structure of Homogeneous Isotropic Materials

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Journal of Electromagnetic Analysis and Applications 2009年第4期1卷 236-239页

作者： Jun DING Yang LIU Chenjiang GUO Qian XU School of Electronic and Information Engineering Northwest Polytechnical University

The perfect cylindrical cloak requires three spatial variant material parameters, which is very difficult to realize in practice [Science 312, 1780 (2006)]. The approach of realizing the electromagnetic cloaking by concentric layered structures instead of using the metamaterial was presented [Optics Express, Vol. 15, No. 18 (2007)]. We use the concentric layered structures to realize a simplified cylindrical cloak with improved parameters and an ideal cylindrical cloak with spatially invariant axial material parameters. Numerical simulation results validate that cloaking performance is significantly improved compared with previously proposed multilayered cloak.

关键词： Cylindrical cloak Concentric Layered Structures

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clock、cloak和钟

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语言教育 1999年第2期 61-页

作者：王绍灵

clock[kl/nk]是“钟”的意思,但在现代英语里它只表示计时的“时钟”,而不表示由铜铁铸成用来敲打发声的“钟”。然而,追溯它的历史可知它的前身却正表示敲打发声的“钟”

关键词：拉丁语 cloak clock

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In-Plane Semi-Linear cloaks with Arbitrary Shape

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Acta Mechanica Solida Sinica 2019年第3期32卷 277-286页

作者： Dengke Guo Zheng Chang Gengkai Hu Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of Education School of Aerospace Engineering Beijing Institute of Technology Beijing 100081 China College of Science China Agricultural University Beijing 100083 China

Soft materials with semi-linear strain energy function can be used as smart transformation media to manipulate elastic waves via finite pre-deformation. However, the intrinsic cons train ts involved in such materials limit the shapes of t ransformation devices to very sim - pie cases. In this work, combining theoretical and numerical analyses, we report an approach of achieving the in-plane elastodynamic cloak with arbitrary shape. We demonstrate that with the appropriate out-of^plane st retch applied on the semi-linear material, cloaking effec t can be achieved for both P- and SV-waves in the symmetrie plane of a 3D domain, and the performance of the cloak with arbitrary cross section can be guaranteed for relatively small in-plane rot at ion. In addition, we propose an empirical formula to predic t the deformation limit of the cloaks with semi-linear materials. This work may stimulate the experimental research on softmatter- based transformation devices. Potential applications can be anticipated in nondestructive testing, structure impact protection, biomedical imaging and soft robotics.

关键词： Elastic waves cloak Hyperelasticity Semi-linear Arbitrary shape

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Remote acoustic cloaks

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Frontiers of physics 2011年第1期6卷 65-69页

作者：苏强刘斌黄吉平 Department of Physics State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures （Ministry of Education） Fudan University Shanghai 200333 China

Due to the correspondence of the acoustic equations to Maxwell＇s equations of one polarization in two dimensions, we exploit theoretically the acoustic counterpart of the recently proposed remote invisibility cloak. The cloak consists of a circular cylindrical core with designed bulk moduli, and an ＂anti-object＂ embedded inside a shell with anisotropic mass densities. The material parameters of the cloaking shells are obtained by using the coordinate transformation method. The essence of the new design of cloaks relies on the ability that the cloaked object is no longer deafened by the cloaking shell, which is verified by both the far-field and near-field full-wave finite-element simulations in two dimensions.

关键词： cloak acoustics finite-element simulations

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The NCC: An Improved Anonymous Method for Location-Based Services Based on Casper

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国际计算机前沿大会会议论文集 2017年第2期 129-131页

作者： Wenqi Liu Jie Feng Guangwei Wang University of Electronic Science and Technology of China Chendu 610000 China Huawei Technologies Co. Ltd. Chendu 610000 China

Casper cloak is a privacy protection method based on K-anonymity algorithm. To be anonymous, Casper cloak needs to search regional sibling and parent node, which requires a complex process and huge expenditure. In addition,the anonymous area has space redundancy and it is not accurate enough to achieve high Location-Based Services (LBS) quality. To address these problems,this paper proposes an improved privacy protection method-NCC, based on the Casper cloak. To reduce the unnecessary search, NCC introduced the concept of the first sibling node. NCC also improves the LBS quality by considering the characteristics of user mobility. Moreover, the improved method,NCC, which is incorporated with a redundancy optimization processing strategy,realizing more precise in the anonymous area and accurately guaranteeing the related degree of privacy. Adopting NCC verification experiments reflects varied advantages as bellow: (1) By reducing 80% searching time, NCC highly improved searching process. (2) The anonymous area produced in NCC not only meet users' anonymous demands, but the direction of the mobility which improves 4 times accuracy of services in comparison with Casper mode.(3) According to optimization strategy, NCC can reach minimum anonymous area index, increasing the rates of anonymous optimization in original algorithm.

关键词： Privacy protection Casper cloak Location-based services Redundancy optimization

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